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WRATTENLIGHT FILTERS

A book of reference for photographers,

industrial and scientific laboratory technicians

and others who require information

concerning the selective

absorption of light

FIRST EDITION 1953

ErrataPage 32.

Page 47.

Page 49.

Page 55.

Page 81.

Page 82.

The Kodak Filter CK.3 is available as a glass filter only.

'Wratten' Filter No. 70. Transmission at 700miA. should read 79.0%.

'Wratten' Filter No. 75. Transmission at 700m^. should read 0.14%.

*Wratten' Filter No. 86C. Transmission at 510m|x. should read 81.9%.

The visible spectrum extends from 400m[x. to 700m(x.

Infra-red radiations start at approximately 700m|a..

KODAK LIMITED LONDON

CONTENTSGENERAL INFORMATION page 3

Availability of 'Wrattcn' Filters 4Identification of Filters 4

'Kodak' Non-Photographic Filters 5

Ordering Filters 5

Dimensional Tolerances of 'Wratten' Filters 6

The Care of Filters 6

Selection of Filters for Black-and-White Photography . . 7

Multiplying Factors of Filters 9

FILTERS FOR TECHNICAL AND SCIENTIFIC USES ... 11

'Wratten' Technical Set of 8 Filters 11

'Wratten' Laboratory Set of 50 Filters

'Wratten' Small Laboratory Set of 24 Filters 11

'Wratten' Set of 8 Spectroscopic Filters 12

'Wratten' M Set of 9 Filters 12

'Wratten' Visual M Set of 9 Filters 13

'Wratten' Set of 7 Monochromatic Filters 14

'Wratten' Mercury Monochromatic Set of 3 Filters . ... 14

'Wratten' Special Mercury Monochromatic Filters .... 14

'Wratten' Photometric Filters 15

'Wratten' Neutral Density Filters 16

MISCELLANEOUS FILTERS 17

'Kodak' Filters 17

'Cine-Kodak' Filter CK.3 17

Kodak 'Pola'-Screens 18

Monochromatic Viewing Filters 19

'Kodak' or 'Wratten' Compound Filters 19

FILTERS FOR COLOUR PHOTOGRAPHY 20

Exposing 'Ektachrome' and 'Kodachrome' film 20

Filters for Use in Daylight 20

Filters for Use in Artificial Light 21

Practical Filter Recommendations 23

Filters for Colour Separation Processes ... ..... 24

Filters for Three-Colour Photomechanical Reproductions 24

Filters for the 'Kodak' Dye Transfer Process 25

'Wratten' Analysis Set for Screen Plate 26

'Wratten' Complementary Filter Set 26

Filters for Two-Colour Separation 26

NUMERICAL LIST OF FILTERS 27

'WRATTEN' FILTER SETS 33

SPECTROPHOTOMETRY ABSORPTION CURVES AND DATA 35

COLOUR SPECIFICATION 71

COLOUR TEMPERATURE CORRECTION 79

Mired Shift Values 79

TECHNICAL DEFINITIONS 81

Density/Per Cent. Transmission Tables 84

APPENDIX'Kodak' Combination Lens Attachments 86

Product titles appearing thus—'Kodak'—are trade marks

GENERAL INFORMATION

'Wratten' light filters have, since 1909, been recognised as occupying a

unique position in photographic, technical, and scientific work. This

has been due, in part, to the wide range of filters available, to their exact

adjustment for the purpose for which they were designed, and to the great

care exercised in their preparation. The standardization for each filter for

colour and spectral transmission has been carefully worked out and the

standards adopted have been rigidly adhered to.

In addition to the wide range of 'Wratten' filters available, a series of

'Kodak' filters is now offered. 'Wratten' filters are prepared from organic

dyes, of which a large number have been investigated in the Kodak

Research Laboratories. The dyes are obtained from a number of sources,

and many have been specially synthesized. Thorough study of the dyes

has resulted in a series of filters of great purity and brightness. The

niters are made by incorporating dyes in gelatine, and coating the proper

amount on to prepared glass. After the coating is dry, it is stripped from

the glass, and gelatine film filter results. Each filter is standardized, by

comparison with a permanent standard, in special instruments which apply

an optical form of limit gauge to its colour.

There will be found included in the fists later in the book, special sets of

filters suitable for experimental work, contrast photography of coloured

objects, colour photography and cinematography, photomicrography,

spectroscopy, photometry and many other applications in fields of both

photographic and non-photographic science.

Kodak Limited will always be glad to offer suggestions as to niters for

any special purpose, and to put their experience and the resources of their

laboratories as far as possible at the service of investigators.

The data given in this book are representative of standard samples of

the materials in question. They are intended only for the information of

users in choosing filters which will meet their requirements. Values read

from the tables of data should not be used by research workers as representing

precisely the absorption characteristics of a particular filter. If such precise

data are needed, they should be determined for the particular filter being

used. If facilities are available, this can be done by the user of the filter.

If not, such calibrations can be readily obtained from the National Physical

Laboratory, Teddington, Middlesex.

Information regarding the use of niters in general amateur, professional

and commercial photography can be found in the publication Kodak and

Wratten Filters. For information on the application of niters to micro-

scopy, the publication Photomicrography should be consulted.

Availability of 'Wratten' Filters

'Wratten' filters are supplied in the form of gelatine film, or of gelatine

film cemented between optical glasses which are available in four standards

of surface accuracy. Filters in "B" glass are cemented between sheets of

plane-parallel glass, which is surfaced in quantity and is of sufficient

accuracy for general photographic work and for many scientific purposes,

such as spectrography or photomicrography. This glass is not sufficiently

accurately surfaced for use in photography with large-aperture lenses of

long focal length. For this purpose filters are supplied in "A" glass, which

is in the form ofoptical flats of the highest quality.

Filters used for cinematography must have a very high standard of

optical accuracy owing to the high resolution of normal cine lenses, and

the enormous magnification of the projected image. For this purpose,

filters are supplied mounted in specially selected "Cine" quality glass.

These filters are of a higher standard of accuracy than "B" glass filters,

without the inevitable bulk and expense of an "A" quality optical flat.

Filters mounted in "D" quality glass are for visual use only. They are

sufficiently accurate for visual photometry, microscopy and work of

similar nature, but are not suitable for use over a camera lens.

Briefly, 'Wratten' filters are available in the following forms :—

GELATINE FILTERS Can be cut to any shape, easily replaced if damaged.

They are, however, easily damaged by fingermarks

and cannot be effectively cleaned.

Optical flats of the finest quality, suitable for use

with the highest quality lenses.

•CINE" QUALITY GLASS Plane-parallel glass of the highest quality, suitable

for use with long-focus lenses and cine lenses.

Suitable for most applications of photography using

standard lenses.

Plain glass—free from blemishes—suitable for

visual use only.

«A" QUALITY GLASS

"B" QUALITY GLASS

"D" QUALITY GLASS

Identification of Filters

Filters mounted in metal rims for use in 'Kodak' Lens Attachments,

have the filter code number machine-engraved on the rim. Unmounted

niters, both circular and square, carry the same information on a transfer

which is affixed to the edge of the filter. These transfers are not easily

damaged, but care should be taken not to scratch them in use.

Filter code numbers. Each filter is identified by a code consisting of a

number, or a combination of a number and a letter, e.g., 'Wratten' No. 22,

or 'Wratten' Filter No. 23A. The letter in this case denotes a modifica-

tion or variation of the original filter specification which may or may not

be also in current use.

Some of the niters which have been in common use for many years have

been identified by a code letter, in some cases followed by a single figure

denoting a modified specification. For instance, the standard tri-colour

set of filters consisting of 'Wratten' filters Nos. 25, 58 and 47 are often

called the A, B2 and C5 filters. The latter style of identification is being

discouraged ; however, for the convenience of those who are more

familiar with the obsolescent codes, they are given in parentheses after

the Wratten filter number in the list of filters on pages 27 to 32.

Filter Names. Some 'Wratten' niters, particularly the tri-colour and

complementary filters are occasionally referred to by names such as Tri-

colour Red and Minus Green, etc. Where these names are ofsome value,

they are also included in the list.

'Kodak' Non-Photographic Filters

Occasionally filters having absorption characteristics different from any

found in the range of 'Kodak' or 'Wratten' filters are required for non-

photographic purposes. Kodak Limited will undertake to design and

manufacture such niters to individual specifications, provided, of course,

that the order is for an economic quantity. Such filters are allotted a

code number consisting of the first two figures of the dominant trans-

mission wavelength in millimicrons prefixed by the figure 5. Further

variations of the same filter are indicated by a progressive figure following

an oblique stroke. For example, a specification resulting in a filter

possessing a transmission the dominant wavelength of which is 570 m,u

would be referred to as a 'Kodak' Filter No. 557. Further variations of

the same filter would be denoted thus : 557/1, 557/2, etc.

Save under specified circumstances, filters manufactured for non-

photographic purposes are not prepared to such fine limits as are 'Wratten'

filters; they are, however, adequate for the purpose for which they are

designed.

Kodak Limited will always be glad to advise enquirers on the use and

selection of filters for non-photographic purposes.

Ordering Filters

When filters are ordered, the number of the filter, whether it should be

circular or square, and the size should be given. A statement should also

be made as to whether it is wanted in the form of gelatine film (squares

only) or cemented in A, Cine, B or D glass. (Note that certain filters are

only available as cemented niters.)

Where filters are listed in sets of a regular size, those sizes will generally

be in stock, but it is not possible to keep in stock cemented filters of all

possible sizes ; therefore, when an unusual filter, compound filter, or a

special size is ordered, it may have to be specially cemented ; this will

involve some delay ; information regarding delivery can be obtained on

request. When ordering filters with metal rims to fit 'Kodak' Lens

Attachments, the code number of the attachment should be quoted (see

page 86). When ordering cemented filters complete with mounts, it is

important to quote the outside diameter of the lens mount (preferably in

millimetres) to enable us to supply the correct combination of filter andlens attachment.

Filters are normally available in a range of standard sizes up to a maxi-

mum of 4 in. square ; sizes larger than this are usually the subject of

special negotiations.

Dimensional Tolerances for 'Wratten' Filters

'Wratten' light filters are subject to a small manufacturing tolerance on

all dimensions. These are kept to the minimum practicable figure. The

tolerance on thickness is governed by the quality of glass in which the filter

is mounted. Lateral dimensions, such as the diameter of a filter, are

subject only to a negative tolerance ; this ensures that a filter of a stated

size will always fit a mount ofcorresponding specification.

Tolerance for diameter, height or width

for all sizes and qualities of 'Wratten' Filters

+0.000 in. -0.0 1 5 in.

Thickness of 'B'

Size

up to and including lft in.

2 in.

2* in.

3 in.

4 in.

'Cine' and 'D' quality filters

Circles

2.2 mm. to 3.5 mm.3.5 mm. to 4.5 mm.5.0 mm. to 6.5 mm.5.0 mm. to 6.0 mm.6.0 mm. to 7.0 mm.

Squares

2.2 mm. to 3.3 mm.3.5 mm. to 4.5 mm.5.0 mm. to 6.5 mm.7.0 mm. to 8.0 mm.8.0 mm. to 10.0 mm.

Thickness of «A' quality (optical flat) filters

Size Circles and Squares

up to and including If in. 7.0 mm. to 8.0 mm.4 in. 13.0 mm. to 14.0 mm.

The Care of Filters

In its simplest form, gelatine film, a filter requires a considerable

amount of care in handling. If it is used in front of or behind the lens in

any form of carrier, it should be removed after use and placed, in clean

paper, between the leaves of a book, where it will keep flat and dry.

Moisture tends to cloud gelatine film filters. The fingers are invariably

moist and, to a certain extent, greasy ; hence in handling gelatine films

care must be taken to hold them by the extreme edges only.

If it is necessary to cut the filter, it should be placed between the leaves

of a folded sheet of paper, on which the exact size has been marked, then

cut paper and filter together with a sharp pair of scissors (the card packed

with each sheet of 'Wratten' gelatine filter is printed with a series of

standard circles and is a handy guide for cutting circular shapes).

Cemented filters should be treated with care equal to that accorded to

lenses. They should be kept in their cases, and on no account allowed to

get damp or dirty. A filter should never be washed with water in any

circumstances, because if water comes in contact with the gelatine at the

edges of the filter, it will cause it to swell and separate the glasses, so that

air can enter between the gelatine and the glass. Even if the swelling does

not cause air to enter in this manner, the filter will be strained and the

definition spoiled.

Filters are cleaned when packed for distribution and with reasonable

care they can be used indefinitely. If, for any reason, a cemented filter

becomes so dirty that it cannot be cleaned by simply polishing after

breathing on it, a piece of soft cloth or lens tissue moistened with 'Kodak'

Lens Cleaning Fluid can be used : special care should be taken to ensure

that the liquid does not come in contact with the cemented edge of the

filter. Before attempting to clean a filter, it is well to make sure that the

surfaces of the glass and the tissue or cloth are free from grit which may

scratch the glass.

Normal filters should never be subjected to undue heat. Temperatures

above about 100° F. tend to soften the cement and to cause the gelatine

to contract. As far as possible, filters should always be protected from

heat. For special purposes, such as in optical instruments employing

high-intensity light sources, filters can be specially produced using a

cement which will withstand much greater extremes of temperature.

These filters are usually the subject of special negotiations. In photo-

micrography and similar work, the image of a high-intensity light source,

such as an arc, should never be focused on the filter.

When used under tropical conditions, filters should be treated with the

utmost care. They should be cleaned frequently to prevent damage from

the growth of fungi on glass surfaces and edges. Dry storage conditions

are very desirable ; a desiccated, hermetically sealed container is usually

satisfactory.

Selection of Filters for Black-and-White Photography

As an elementary aid to the selection of filters to produce a desired

photographic effect, the information given below may prove of value. In

referring to this information, however, it cannot be assumed that all filters

which bear a similar colour description have the same effect. For

example, deep-coloured filters, at their point of minimum transmission,

may have nearly one hundred per cent, absorption, showing an almost

complete cut-off at that particular wave-length. Filters of similar colour

but lower density, on the other hand, may only have a maximum absorption

of twenty per cent, or less, and transmit all colours of the spectrum to

varying degrees.

From this it may be seen that for specialized work the specific absorption

characteristics of each filter must be taken into consideration. For

general photographic work, however, it is usually sufficient to assume that

the absorption of a filter is confined to the primary and complementary

colours only, as follows :

Primary colours

Complementary colours

Red .

GreenBlue .

absorbsabsorbsabsorbs

(Red + green = yellow .

Red + blue = magenta

.

(Green + blue = cyan. .

green and blue

red and bluered and green

. . . absorbs .

absorbs .

absorbs .

bluegreenred

It should be borne in mind that the photographic result obtained by the

use of a filter depends very much on the spectral sensitivity of the material

used in the camera ;panchromatic emulsions should, in general, be used,

but orthochromatic emulsions may be used in certain limited

circumstances.

A coloured object will appear dark in a print if the photograph is taken

through a filter which absorbs the colour of the light reflected from or

transmitted through the object. This is because the filter allows only a

little of this light to reach the sensitized material, so that the object seems

to be a dark one. For example, when photographing a blueprint the

greenish-blue ground should be made as dark as possible compared with

the white lines. A red filter absorbs green and blue light and the greatest

contrast would be obtained by the use of a filter of this colour. In this

case, the combination ofthe 'Wratten' No. 25 or No. 29 filter and panchro-

matic material would be found most suitable. If the blueprint were

a pure primary blue, a yellow or green filter would do just as well, but as it

is, in fact, a very greenish blue, the resulting contrast would not be

as high.

Conversely, a coloured object will appear light in the final print, if the

photograph is taken through a filter which transmits the colour of the light

reflected from or transmitted by the object. For this reason a document

yellowed with age, or bearing a yellow stain, should be photographed

through a medium yellow filter such as the 'Wratten' No. 9 (K3), when it is

required that this background shall be all of one even density. This

accentuates the contrast between the print and the background and

eliminates the contrast between the stain and the background.

These same principles should, in general, be applied in the selection of

filters for other coloured subjects. Green foliage will, for instance, be

lightened, and will thus show the optimum detail of light and shade when

the negative is made on panchromatic material exposed through a green

filter, such as the 'Wratten' No. 11 (XI) or, more drastically, through the

tri-colour green filter 'Wratten' No. 58 (B2). In this instance the desired

effect can equally be obtained with an orthochromatic material exposed

through a medium yellow filter such as the 'Wratten' No. 9 (K3).

Selection of the proper filter for multi-coloured subjects demands

judgment of the circumstances. No single rule can be applied, and the

problem may call for careful consideration. The subject should first be

examined closely to determine how the various colours are required to be

rendered in order to show a particular pattern or texture, or in order to

make an object either appear prominent against, or merge with, surround-

ing objects or the background. It may be obvious that certain colours

should be lightened, and others darkened, to achieve the desired effect. If

so, the best method of selecting the appropriate filter is usually that of

exarnining the subject visually through various filters ; but, as the

sensitivity ofthe human eye is slightly different from that ofa photographic

emulsion, it is as well to make photographic tests as a check. If it is not

evident which of the colours should be rendered lighter or darker than

normal, the subject should be photographed on a panchromatic material,

using, in daylight, a 'Wratten' No. 8 (K2) filter or, in tungsten light, a

'Wratten' No. 11 (XI) filter. The resultant print will reproduce, approx-

imately, the relative visual brightness values of the subject. If, however,

this normal rendering is not entirely suitable, the choice of a moreappropriate filter for a second negative will then have been greatly

simplified.

The reference table below shows the filters by means of which some of

the more common colours may be reproduced in light or dark tones.

Subject

Colour

Subject

ExamplesTo reproduce

lighter use—To reproduce

darker use—

Red

Orange

Magenta

Yellow

Green

Blue-Green

Blue

Buses, post boxes, flowers, etc.

Bricks, furniture etc.

Clothing, flowers, etc.

Sand, old documents,flowers, clothing, etc.

Foliage, buses, etc.

Flowers, clothing, etc.

Sea, sky, flowers, clothing, etc.

15, 25 or 29

15 or 25

32

8 or 12

1 1 or 58

44

38 or 47

47 or 58

1 1 or 47

58

38 or 47

15. 25 or 47

15 or 25

8, 12 or 25

MULTIPLYING FACTORS OF FILTERS

Since a filter absorbs part of the light, its use in photography involves an

increase in exposure corresponding to the proportion of effective light

absorbed.

The number of times by which the basic " no filter " exposure must be

increased to compensate for a given filter, used with a given sensitive

material, is called the multiplying factor of the filter, i.e., the filter factory

and this will depend both on the colour sensitivity of the photographic

material and on the light-source used. A red filter, for instance, may

increase the exposure some hundreds of times with a material having very

little sensitivity to red, while with a very red sensitive material it may

increase the exposure only five times. The same conditions apply to the

use of different light-sources. It is meaningless, therefore, to refer to

filters (other than Neutral Density filters), as " two times " or " four

times " filters.

To determine filter factor values in the laboratory, exposures arc made

on various 'Kodak' sensitized materials on an intensity-scale sensitometer

for l/25th sec, both to standard tungsten and to standard daylight

illumination. From the resulting strips the characteristic curve for the

material can be plotted and the filter factor then measured at a density of

1.0 above fog. The values so found therefore represent standard samples

of niters and sensitive material exposed to a standard light-source. In

practice, where the quality of light may be entirely different, a quite

different factor may apply, and exact exposures must therefore be found

by trial under the actual conditions of use.

The following procedure can be used to determine the filter factor that

applies to actual working conditions and to specific photographic equip-

ment and materials. Select a scene containing a neutral-grey area and

make one exposure without the filter. Then, with the filter in position,

make a series of exposures of the same scene. Start the series with a lens

opening one-half stop larger than the one used without the filter. Progress

by half-stops through a range of 2-3 stops. Match the density of the

neutral area in the unfiltered negative with the density of the same area

in one of the filtered negatives. The factor for that particular filter can

then be calculated from the difference in exposure between the two

negatives.

It is important that, when matching the density of the neutral area, the

gamma values of the two negatives must be roughly equal ; a 25 per cent,

increase in development is recommended for negatives made through a

dark blue filter to compensate for the loss of contrast.

For very critical work, tests should be carried out using shutter speeds

similar to those which are to be used in practice.

As a guide, the table below suggests approximate factors for some of the

more popular 'Wratten' light filters for both average daylight and tungsten

illumination. For filter factors relating to specific sensitized materials

reference should be made to the instruction sheets which are included in

each pack.

APPROXIMATE FILTER FACTORS

COLOUR OF FILTER

PANCHROMATIC ORTHOCHROMATIC

Daylight Tungsten Daylight Tungsten

Yellow (No. 8)

Yellow-green (No. II)

Orange (No. 15)

Red (No. 25)

Green (No. 58)

Deep blue (No. 47)

Deep red (No. 29)

Deep green (No. 61)

Very deep blue (No. 49)

2to2±4 to 6

2to2±5 to 8

7 to 15

6 to 7

7 to 16

\{ to 2

4 to 6

\i to 2

3 to 4

5 to II

7 to 16

7 to 8

10 to 15

25 to 80

2 to 4

4 to 5

3 to 5

2 to2£3 to 4

2£to3

FILTERS FOR TECHNICAL ANDSCIENTIFIC USES

'Wratten' filter sets contain a selection of 'Wratten' niters specially

chosen as being the most useful elements for the purpose for which they

are intended. Where a set contains a tricolour set of filters (Nos. 25, 58

and 47 or 29, 61 and 49) these are specially matched for optical perform-

ance to ensure accurate registration. All sets are supplied in cases.

•Wratten' Technical Set of 8 Filters

Nos. 3, 8, 11, 15,25,29,47,58.

The 'Wratten' Technical Set of 8 Filters is designed to provide for the

majority of subjects arising in technical and commercial photography.

This set represents a selection of the most generally used filters in the

Wratten range. These are as follows :

Nos. 3, 8 and 11, which arc normal correction filters, No. 15, a

deep yellow filter for contrast work, Nos. 25, 58 and 47, the

standard tri-colour set, and No. 29 a deep-red filter for special work.

For those who do not require this full set, Nos. 8, 15 and 25 filters are

recommended. Occasions may arise, however, when other niters than

these will be required. When much technical or commercial work is done,

a full set oftechnical filters will be found most useful.

•Wratten' Laboratory Set of 50 Filters

Nos. 1A, 2B, 3, 8, 11, 12, 15, 18A 22 23A, 25 29,30,32 35 36,

38, 44, 45, 47, 49, 50, 58, 59, 61, 66, 70, 72B, 73, 74, 75, 76, 77,

78A,78C; 81, 81EF, 82, 8^ 85B, 86A, 86C, 87, 88A, ND.0.1,

ND.0.2, ND.0.5, ND.0.8, CC-20Y, CC-05M.

The Laboratory Set of 50 Filters has been selected for use in laboratories,

schools, universities, research stations and other places where the behaviour

of light is demonstrated, observed or employed. By the appropriate

choice of niters or combinations of filters various parts of the spectrum

can be isolated, absorbed or suppressed to suit most requirements of

experiment or demonstration.

'Wratten' Small Laboratory Set of 24 Filters

Nos. 2B, 8, 11, 12, 15,22, 25, 29, 32, 35, 44, 45,

47, 50, 58, 59, 61, 70, 72B, 73, 74, 75, 76, 88A.

For those who do not require the full set of 50 filters this smaller set is

available.

Other niters (except those filters bearing special prices) can be substi-

tuted if required. Both Laboratory Sets, which are normally supplied in a

fitted mahogany case, include matched tri-colour filters, M filters for

microscopy, complementary and monochromatic sets.

10

'Wratten' Set of 8 Spectroscopic Filters

No. Characteristics2B High absorption to 410 mji.8 High absorption to 470 my15 High absorption to 510 m\i25 High absorption to 590 m(x29 High absorption to 610 mn70 High absorption to 650 m|x36 (plus No. 15) High absorption to 680 mn18A Absorbs visual violet for

photography of ultra-violet

These filters represent a progressive colour absorption from 410 mn to680 my, the need for which may arise in scientific work, as for example forthe suppression of short wavelength flare light in spectrography.

'Wratten' M Set of 9 Filters

Nos. 11, 15, 22, 25, 29, 35, 45, 47, 58.

To enable the microscopist to control accurately the contrast anddefinition of his photomicrographs the 'Wratten' M Set of 9 Filters is

supplied. These filters have been specially selected for their great purityand brightness of colour and their sharp absorption characteristics.Besides their use singly they can be used in pairs, when the spectrum can beresolved into substantially monochromatic divisions. (See curves for certainpairs of filters—pages 57 to 60.) They are intended for use interposedbetween the light source and the sub-stage condenser; some microscopesmake provision for such filters in a fitting attached to the sub-stage of theinstrument. Spectral transmissions of these filters are given below:—Filter No.

255847

35

2229154511

Visual ColourRedGreenDeep blue

Deep magenta

Deep orangeDeep redVery deep yellowBlue-greenLight yellow-green

Spectral TransmissionFrom 590 my to red endFrom 480 my. to 620 my.From 370 my. to 510 my.

J From 320 m\x to 470 m^\ From 650 my. to red endFrom 550 mix to red endFrom 610 my. to red endFrom 510 my to red endFrom 430 my to 540 m^Correction filter for usein tungsten light

When selecting a filter, care must always be taken that too muchcontrast is not obtained, or the result will be a choking of shadows and lossof detail. It can be seen from the following table that a considerablechoice of dominant wavelengths is available.

Filters Dom. Wjlgth. Colour35 plus 45 445 Violet47 plus 45 460 Blue58 plus 45 510 Bluish-green15 plus 45 525 Pure green58 plus 15 540 Yellowish-green58 plus 22 575 Greenish-yellow25 600 Red29 625 Deep red25 plus 35 670 Very deep red

The more nearly monochromatic thethe image from an achromatic objective.

12

illumination, the better will beThe following 'Wratten' filters

are especially useful with achromats since they transmit the proper green

light (given in the order of decreasing breadth of transmission band) :

Nos. 11, 58, 58 plus 15, 61, 15 plus 45.

The spherical aberration of achromatic objectives is best corrected for

die region ofthe spectrum transmitted by the 58-f 1 5 filters . Hence, whenthe specimen is colourless, as it frequently is in metallography, the

illumination is restricted by these filters, or their equivalent, in order to

use achromatic objectives most efficiently. Apochromatic objectives

also give better definition when the illumination is restricted by a colour

filter.

For a detailed account of the use of the 'Wratten' M Set of 9 Filters,

the reader is referred to the 'Kodak' publication Photomicrography.

•Wratten' Visual M Set of 9 Filters

Nos. 15, 22, 25, 38A, 45, 58, 66, 78A, and ND.1.0.

A set of special filters intended for visual work with the microscope.

The set consists ofnine circular filters cemented in "D" quality glass and is

supplied complete in a case. They are intended for use in the sub-stage

condenser ring of the microscope and are made from special thin glass to

allow their use in pairs ifrequired.

Their use enables microscopists to examine specimens under the most

convenient and favourable conditions. The use of the blue filter 'Wratten'

No. 78A for example, converts tungsten illumination to the approximate

equivalent of daylight, and thus creates the effect of viewing by daylight

illumination. By choosing other niters in this set, selective increase in

the effective contrast between different colours of the specimen, separation

of the specimen from the background, and an increase in the resolution of

fine detail can be achieved.

No. Colour Use

78A Light blue A photometric filter made to convert the illumination quality

of light from incandescent tungsten lamps of the commontype to that which is visually equivalent to daylight. Sucha filter is often employed for viewing coloured specimenswith their commonly accepted standard daylight appearance.

38A Blue A filter for increasing the apparent contrast in faintly stained

yellow or orange preparations. Helps in the resolution of

fine detail.

Especially useful when the highest resolving power visually

possible is required, as in the study of diatom structure. It

has no red transmission and its dominant wave length is at

about 480 my.A contrast filter for use with pink and red-stained prepara-

tions. Preferred by some v/orkers for general use in place ofNo. 78A.A contrast filter for use with faintly stained pink or red

preparations.

For increasing the contrast in blue preparations and for

helping in the observation of detail in insect mounts byreducing the contrast between the preparation and the back-

ground.Contrast filter for use with preparations stained with methy-lene blue, methyl green, etc.

ND 1.0 Neutral A filter for moderating the intensity of the illumination. Thedensity density supplied transmits one-tenth of the incident light.

45 Blue-green

66

58

15

22

25

Very light

green

Green

Very deepyellow

Deep orange

Red

13

'Wratten' Set of 7 Monochromatic Filters

70 Very deep red72B Very deep orange-red73 Very deep yellow-green74 Very deep green

75 Very deep blue-green76 Very deep violet

88A Visually Opaque(infra-red)

A set of seven filters embracing the range of 320 my. to the red end of the

spectrum, for isolating light ofnarrow wavelength bands for the determina-

tion of colour absorption factors, colour sensitivity, and similar data.

'Wratten' Mercury Monochromatic Set of 3 Filters

Nos. 22, 50, 74.

The chief lines of mercury-vapour illumination occur at these positions :

Yellow, 577 and 579 m^iGreen, 546 mixBlue-violet, 436 mu.Deep-violet, 405 and 408 mu.Ultra-violet, 365 and 398 my.

The wide separation of these lines and the great intensity of mercury-vapour lighting make it very suitable for use as a source of monochromaticillumination. For the isolation of the most generally used lines, the

following three mercury monochromats have been prepared :

No. 22 (yellow monochromat) —Transmits yellow lines (577 and 579 m^) andall longer wavelengths.

No. 50 (violet monochromat) —Transmits lines of wavelength 436 mu, and, to

a lesser extent, 398 mu. and 408 mu.No. 74 (green monochromat) —Transmits approximately 10 per cent, of green at

546 my. and about 0.2 per cent, of yellow lines.

'Wratten' Special Mercury Monochromatic Filters

Nos. 18A, 18B, 77, 77A.

In addition to the standard set of mercury monochromats, four special

niters are available. To isolate the green (546 my.) line of the mercury-vapour lamp and to suppress the powerful neighbouring band of yellow,

the No. 77 filter has been prepared. This filter transmits 74 per cent, ofthe green line and about 0.2 per cent, of the yellow lines. Where the

yellow lines must be suppressed still further, the No. 77A is recom-mended. This filter transmits approximately 68 per cent, of the green

546 m\i line and only a negligible amount at 577 my. Where the red lines

of the quartz lamp are objectionable and must be eliminated, a No. 58 filter

should be superimposed on either a No. 77 or a No. 77A.

For the isolation of the mercury line at 365 mu. in the ultra-violet, filter

No. 18A is available. This filter transmits approximately 65 per cent, ofthe 365 my line, and, when it is used with a light-source giving a continuousspectrum, it affords a means of obtaining ultra-violet radiation of a fairly

narrow band having its maximum at 363 my..

For those who require a filter having a higher transmission factor thanafforded by the No. 18A filter, the 'Wratten' No. 18B filter is recom-mended. This filter has a transmission of approximately 78 per cent,

from 290 my. to 370 mu and provides an ample source of near-mono-chromatic illumination for micrographic, microscopic and photographicinvestigation by ultra-violet light.

14

'Wratten' Photometric Filters

Nos. 78A, 78C, 86A, 86C.

When light-sources of different colour temperatures are compared by

means of a photometer, the colour difference introduces difficulty in

making an accurate balance. This difficulty can be eliminated, or at least

lessened considerably, if a selectively absorbing filter is placed on one side

of the photometer head. The difference in colour between the two parts

of the photometric field can then be eliminated, or reduced to such an

extent that it no longer interferes with the precise judgment of brightness

equality. The transmission of the filter for light of the spectral quality

which is incident upon it in the photometer must, of course, be deter-

mined. This calibration can, however, be made by taking a sufficiently

large number of observations to obtain the desired precision.

'Wratten' Photometric filters are designed for the elimination of these

disturbing colour differences in all types ofphotometric work. In present-

day photometric practice, the standard of luminous intensity is almost

invariably an electric incandescent lamp standardized for candle power.

In order that this standard shall have a satisfactorily long life, it is neces-

sary that it be operated at a relatively low filament temperature. This

means that the light emitted by such standards is usually much more yellow

than the illumination with which it is to be compared, which may come

from commercial tungsten incandescent lamps operating at much higher

temperatures, arc lamps of various kinds, or from natural sources, such as

the sun or sky.

Two series of photometric filters are provided. The No. 78 series

consists of bluish niters designed, in general, to be placed on the standard

lamp side of the photometer or illuminator. The No. 86 series consists of

yellowish niters, designed to be placed on the test or comparison side ofthe

photometric instrument.

In the following tables the colour differences which can be compensated

for by the various photometric filters are shown in terms of colour tempera-

ture differences. Standard lamps are normally operated at a colour

temperature of approximately 2360° K. This value, therefore, is taken as

the reference point in listing the colour difference for which each filter (or

filter combination) will compensate.

No. 78 SERIES (BLUISH)

For increasing colour temperature

No. 86 SERIES (YELLOWISH)

For decreasing colour temperature

78A+78A raises 2360°K to 5000°K

•78A+78C+78C. 2360°K to 4400°K

78A „ 2360°K to 3200°K

78C+78C ,. 2360°K to 2666°K

78C ., 2360°K to 2500°K

86A+86A reduces 5000°K to 2360°

K

86A ,. 3200° K to 2360*

K

86C+86C .. 2666 K to 2360"K86C .. 2500° K to 2360'K

* For visual use only.

15

Note: These filters are subject to the limitations of commercial produc-tion, though the tolerances have been reduced to the minimumpractical values ; if they are to be used under circumstances wherehigh precision is required, they should be individually calibrated.

It should be emphasised that the photometric filters are designed prim-arily for visual use to reduce the colour differences between illuminantsoperating at different colour temperatures. They can, however, be usedto introduce slight colour correction to the light-source when exposingcolour films, provided that their limitations are realised and allowed for.

As a guide to the selection of photometric niters for various types ofwork, the following table is given which shows the approximate colourtemperature of light from various sources used in practice.

PRACTICAL SOURCES OF ILLUMINATION

Source Colour TemperatureSkylight 12000° -18000° KHigh-intensity carbon arc (sun arc) 5500° KSunlight (mean noon) 5400° KWhite-flame carbon arc 5000° KCrater of carbon arc (ordinary hard-cored) 4000° KIncandescent tungsten 27.3 lumens /watt 3220° KIncandescent tungsten 24.2 lumens /watt 3175° KIncandescent tungsten 20.3 lumens /watt 2985° KIncandescent tungsten 10.0 lumens /watt 2500° K

'Wratten' Neutral Density Filters

Neutral-density filters are of use in many branches of optical work sincethey permit the reduction of light intensity in a known and definite manner,Those made by Kodak Limited are for use in the visual region of thespectrum. Both the spectral neutrality and the stability are of a highorder. The neutral-density filters are made to have certain definite valuesof optical density, which are measured in terms of diffuse illuminationupon approved types of photometers.

Experience has shown that the transmission of a neutral-density filter

depends, to the extent of two to three per cent., on the optical system withwhich it is used. This is the result of slight scattering of the transmittedlight and inter-reflections. Neutral-density filters are therefore suppliedonly within an accuracy of five per cent, of the stated diffuse contact opaldensity value. It is recommended that for special work they be calibratedby direct measurement under the conditions ofuse.

Special neutral-density filters, calibrated in diffuse contact opal densityvalues, can be furnished to order. Requests for quotations on such filtersshould be accompanied by complete statements of size, precision required,and conditions under which the filters are to be used.

Neutral density filters are regularly supplied in gelatine film or cementedm glass in the following eleven standard densities

:

16

TRANSMISSIONDENSITY MULTIPLYING

FACTORFraction Per cent.

0.1 4/5 80 'i

0.2 7/H 63 1*

0.3 1/2 50 2

0.4 2/5 40 2*

0.5 1/3 32 3

0.6 1/4 25 4

0.7 1/5 20 5

0.8 1/6 16 6

0.9 1/8 13 8

1.0 1/10 10 10

2.0 1/100 1 100

MISCELLANEOUS FILTERS

Under this heading are listed single filters which are not included in sets,

yet are of interest and value for general photographic work. These are

available only as glass filters and are not supplied in gelatine form.

•Kodak' FiltersNos. 4, 11, 15, 25

In addition to the series of 'Wratten' filters listed in this book a popular

range of 'Kodak' filters for general photography is also available.

These filters have absorption characteristics which approximate

sufficiently closely to filters in the 'Wratten' range for the data on one to

apply, for most practical purposes, to the other also.

No. 4: yellow

No. 1 1 : light yellow-green

No. 15: very deep yellow

No. 25: red

These filters are specially designed for use with the 'Kodak'

Combination Lens Attachment System (see pages 86 to 92) and are fitted

with a thin metal rim which facilitates their use interchangeably andensures accurate fitting in the lens attachment.

'Cine-Kodak' Filter CK.3

This filter, medium yellow in colour, is intended for use with 'Cine-

Kodak' cameras and, except when a non-standard size is ordered, is

supplied in a mount to fit the 'Cine-Kodak' lens. It is important therefore

to state, when ordering, the type of 'Cine-Kodak* lens for which the filter is

required.

The CK.3 filter is manufactured from the highest optical quality pot

metal glass, and is worked and tested to ensure the finest optical

performance.

17

Kodak 'Pola'-Screen

Kodak 'Pola'-screens are essentially different from colour filters in so far

as the primary photographic effect is not that of colour absorption but of

selective control over reflections.

The Tola'-screen may be likened to an optical slit which transmits only

light vibrating in the plane of that slit. The intensity of light already

polarised can be controlled by rotation of a 'Pola'-screen in its path. Thebeam is entirely cut off when the vibration plane of the light and that of the

'Pola'-screen are "crossed," and wholly transmitted when the vibration

planes are parallel.

There are two common sources of polarised light in nature :

—

1. Light reflected from a non-metallic surface such as polished wood,glass, water or paint. The maximum degree of polarisation occurs

when the incident light makes an angle of approximately 35° with the

plane of the reflector ; at greater or lesser angles the effect diminishes,

until it disappears entirely at 0° and 90°.

2. Light from a clear blue sky at right angles to the direction of the sunis also strongly polarised ; at other angles polarisation is incomplete,

and vanishes at 0° and 180° from the sun.

By rotating a Kodak 'Pola'-screen in front of the camera lens, reflections

can be diminished or eliminated entirely, according to the degree of rota-

tion of the screen and the angle at which light is being reflected to the

camera.

The effect can be judged by viewing the scene through a 'Pola'-screen,

rotating it until the maximum or the desired effect is obtained, then

placing it over the camera lens with the same orientation.

Application of Kodak 'Pola'-Screens

1

.

A blue sky can be darkened to about the same degree as by the use of

a 'Wratten' No. 25 filter, without affecting the colour rendering ofthelandscape.

2. 'Pola'-screens offer the only known means of modifying sky bright-

ness in colour photography.

3. Reflections on glass or water can be subdued to show detail beyond or

below the surface.

4. Reflections from non-metallic light or high-key backgrounds can beeffectively subdued to show surface detail and texture.

5. 'Pola'-screens over both the lights and the camera lens give complete

control of reflections when copying paintings, prints or murals,

posters and when photographing surfaces showing specular or other

troublesome reflections.

Kodak 'Pola'-screens are physically similar to 'Wratten' filters ; they

may be used in standard filter holders which permit the 'Pola'-screen to berotated in front ofthe camera lens through an angle of 180°.

The colour of the Kodak 'Pola'-screen is a neutral grey having a density

of approximately 0.4, necessitating an exposure increase of 1$ stops.

18

Monochromatic Viewing Filters

Nos. 90, 557/1.

It is, of course, impossible to construct a filter which will remove all

appearance of colour from a subject and at the same time strictly retain the

relative luminosities. These filters which we have produced are, it is

believed, the best compromise which can be obtained. Whilst it is just

possible to distinguish between a bright red and a bright green viewedthrough these filters, the difference between the colours is so dulled that

they no longer materially affect judgment as to their relative luminosity.

This appearance enables workers who are in the habit of using mono-chromatic methods for the reproduction of coloured objects, to study the

relative tonal brightnesses in the subject as a guide to the control oflighting effects, as forexample in motionpicture and commercial studio sets.

No. 90 Monochromatic Viewing Filter for use in daylight.

No. 557/1 Monochromatic Viewing Filter for use with tungsten studio(compound) lighting.

'Kodak' Monochromatic Viewing Filter No. 557/1 is normally supplied in

lf-inch diameter circles. Other sizes can be made to special order.

'Kodak' or 'Wratten' Compound Filters

In many instances, when a single filter does not have the desired effect,

the use of two filters together is indicated. Separate filters, either in

gelatine form or cemented in " A," "Cine" or "B" glass, are quite satis-

factory when used in pairs, but under certain circumstances the extra

air-to-glass surfaces may cause troublesome inter-reflections. These can

be avoided by cementing the two gelatine films between glass as a single

filter. Kodak Limited will cement any combination of filters to special

order. The cementing of more than two separate filters in combination is

not recommended.

The manufacture of compound filters to special order usually involves

extra delay of approximately one week over that normally required for

single filters, owing to the extra drying time required.

19

FILTERS FOR COLOUR PHOTOGRAPHY

Exposing 'Ektachrome' and 'Kodachrome' film

FILTERS FOR USE IN DAYLIGHT

Haze-Cutting Filter

No. 1A.

When photographing landscapes and outdoor scenes, particularly at

high altitudes, the light invariably contains a high proportion of ultra-

violet rays. On black-and-white film this usually records as mist or, as it is

commonly called, " distance haze." Colour materials, however, record

this as a blue haze, which may extend over the entire picture area, giving a

particularly "cold" result.

The 'Wratten' No. 1A filter is a faintly pink filter which absorbs ultra-

violet radiations up to approximately 380 my. and, when used over the

camera lens, reduces the effect of haze, and affords a certain measure of

penetration.

When exposing colour films under conditions when the percentage of

ultra-violet is not above average, the use of this filter may result in a

slightly warmer-than-normal colour rendering.

Correcting Filters

Nos. 80A, 85, 85B.

The colour sensitivity of 'Kodak' colour materials is adjusted to re-

produce the colours of the subject correctly under certain conditions of

fighting. Owing to the widely varying colour quality of both daylight and

artificial light, it is only practicable to balance the colour sensitivity of

'Ektachrome' and 'Kodachrome' film to the quality of the light most used

under practical conditions.

'Ektachrome' and 'Kodachrome' Films (daylight type) are balanced to give

correct colour rendering when exposed to light equivalent in colour quality

to average sunlight plus skylight.

'Kodachome' Type 'A' Film is balanced for light of approximately 3400° K,this being the average colour temperature of standard Photoflood lamps.

'Ektachrome' Type'B' Film, is intended for use in studios equipped with high-

efficiency tungsten illumination having a colour temperature of3100° to 3200" K.

Whilst it is preferable to expose colour films by light of the colour

quality to which they are balanced, this is not always practicable. When it

is found necessary for films intended for use in artificial light to be used in

daylight or vice versa, three special filters are available to provide the

necessary colour temperature shift. The 'Wratten' No. 80A is a pale blue

filter which effectively corrects the colour balance of daylight type colour

materials for use by Photoflood light, the 'Wratten' No. 85 filter corrects

the colour balance of Type 'A' materials for use in daylight and the No.85B allows the use ofType 'B' films in daylight.

20

These conversion filters, of course, can only ensure correct colour

reproduction within the limitations of the materials and the precise

circumstances under which they are used. Under abnormal or extreme

conditions, such as may be encountered at early morning or late evening,

other colour-compensating filters may be required (see page 22).

FILTERS FOR USE IN ARTIFICIAL LIGHT

'Wratten* Light-Balancing Filters

81, 81A, 81B, 81C, 81EF82, 82A, 82B, 82C.

This series consists of eight different niters for the fine adjustment ofthe

colour temperature ofthe light-source when exposing colour materials such

as 'Ektachrome' or 'Kodachrome' film, or for the fine control of colour

reproduction. These filters have an absorption affecting two primary*

colours and fall into two distinct groups as follows :

Blue Series : 82, 82A, 82B, 82C for bluer ("cooler") rendering.

Yellow Series : 81, 81A, 81B, 81C, 81EF for yellower ("warmer") rendering.

These filters are intended for use over the camera lens to increase or

decrease respectively the colour temperature of the studio lighting when

this cannot be conveniently done by regulating the mains voltage. The

depth of colour, hence the change in colour temperature obtained,

progresses throughout the series.

At 3200° K. the changes effected by each set of filters (with the excep-

tion of No. 81EF) are in steps of approximately 100° K., for example, the

No. 81 filter converts 3300° K. tungsten light to 3200° K. and the No. 81A

converts 3400° K. light (Photoflood) to 3200° K. At other colour

temperatures the changes may be more or less than this, according to the

conditions of use : the correct filter should then be found by experiment.

The appropriate choice of filter under these conditions is best made by

means of a colour-temperature meter, or by photographic trial. The table

below shows the change effected by each filter in relation to a standard

light-source of3200° K.

BLUISH FILTERS YELLOWISH FILTERS

'Wratten'

Light

Balancing

Filter

Colour

temperature

raised from

Exposureincrease

'Wratten'

Light-

Balancing

Filter

Colour

temperature

lowered from

Exposureincrease

82

82A

82B

82C

3I00°K to 3200°

K

3000°K to 3200°K

2900°K to 3200°K

280CTK to 3200°K

1/3 stop

1/3 stop

2/3 stop

2/3 stop

81

8IA

8IB

8IC8IEF

3300"K to 3200°K

3400 UK to 3200*

K

3500°K to 3200°

K

3600° K to 3200°

K

3850°K to 3200°

K

1 3 stop

1 /3 stop

1/3 stop

1/3 stop

2/3 stop

* By "primary" colour in this connection is meant a colour whose spectral composition comprises

approximately one-third of the visible spectrum—red, green and blue respectively.

21

'Kodak' Colour-Compensating Filters

These filters are used to make changes in the overall colour balance ofphotographic results obtained with colour films or to compensate for

deficiencies in the spectral quality of the light by which colour films maysometimes be exposed.

FILTERS SUPPRESSING ONE PRIMARY COLOUR

Yellow Series

(suppressing blue)

Magenta Series

(suppressing green)

Cyan Series

(suppressing red)

CC-05Y

CC-IOY

CC-20Y

CC-05MCC-IOMCC-20M

CC-05CCC-IOC

CC-20C

FILTERS SUPPRESSING TWO PRIMARY COLOURS

Red Series

(suppressing blue and green)

Green Series

(suppressing blue and red)

Blue Series

(suppressing green and red)

CC-05R

CC-IOR

CC-20R

CC-05GCC-IOGCC-20G

CC-05B

CC-IOB

CC-20B

Another purpose to which these filters may be put is to introduce slight

colour-correction in light-sources used in making 'Kodachrome' duplicatesfrom 'Ektachrome' or 'Kodachrome' originals. For example, if the dupli-cate appears greenish, one of the pale magenta niters (CC-05M orCC-IOM) can be used over the camera lens; if too pink, one of the greenfilters (CC-05G or CC-IOG) may prove suitable. The only satisfactory

method is to select appropriate filters by experiment. Undesirableoverall tints of colour in transparencies which are to be duplicated orcolour-printed can also be corrected in this manner.

In submarine photography with 'Ektachrome' or 'Kodachrome' film oneof the red series may prove very useful in compensating for the strong redabsorption of the water. It is not possible to make specific recommenda-tions regarding the use of these filters under conditions of this sort, as thecolour of the water varies according to the location, depth, etc.

The range consists of six series, each of three filters, comprising yellow,

magenta and cyan, and red, green and blue as listed above. These filters arespaced according to density and corresponding niters in different series areroughly comparable. The peak density of the niters is indicated by thetwo digits following the hyphen in the filter designation, and the colouris indicated by the final letter. Peak density is measured at the wave-length of maximum absorption, for example, the peak density of a yellowfilter is given for blue light. The density values do not include thegelatine in which the filter dye is suspended, nor the glass in which filters

may be mounted.

22

The red niters contain the same dyes as are used m the yellow and

magenta niters, and in similar amounts ; similarly, the green filters combine

the yellow and cyan dyes, and blue filters the cyan and magenta dyes.

Hence, a CC-05R gives much the same result as a CC-05Y and CC-05Mused together; there is a similar relationship between other corresponding

filters when they are of the same density.

The approximate increase in exposure entailed by using these niters is

of the order of one-third of a stop in all cases except when using the

CC-05Y which requires no increase, and the CC-20B which requires an

increase of two-thirds of a stop.

PRACTICAL FILTER RECOMMENDATIONS

The following table summarises the recommendations which apply

when an 'Ektachrome' or 'Kodachrome' film intended for one type of

illumination has to be used with a different kind of lighting. Owing to

variations in conditions between one studio and another, the filter indicated

in this table may not necessarily be the best possible in every case; but

the recommendations given will provide the best basis for further selection.

Illumination'Kodachrome'Daylight type

'Kodachrome'Type A

'Ektachrome'Daylight Type

'Ektachrome'TypeB

Daylight No filter

required*

'Wratten'

No. 85

No filter

required*

'Wratten'

No. 85B

Clearflash-bulbs

Notrecommended

•Wratten'No. 8IC

Notrecommended

'Wratten'No. 8IC

Photofloodlamps

'Wratten'No. 80Af

No filter

required

'Wratten'

No. 80A'Wratten'

No. 8IA

High efficiency

tungsten

(3200° K) studio

lamps ('Photo -

pearl' or Pearl

Photographic)

Notrecommended

'Wratten'

No. 82A'Wratten'

No. 80A plus

No. 82A

No filter

required

Electronic flash

tubes('Kodatron')

'Wratten'

No. 81

B

Notrecommended

See film

instructions

'Wratten'

No. 85B plus

CC-05M

Daylightfluorescent

lamps

CC-20B Notrecommended

CC-IOM plus

CC-05BNot

recommended

Natural whitefluorescent

lamps

Notrecommended

CC-IOY plus

CC-20MNot

recommendedCC-20R plus

CC-05R

White-flamecarbon arcs

CC-20Y plus

CC-20YNot

recommendedCC-20Y plus

CC-20YNot

recommended

* Exceptions are when an ultra-violet-absorbing (hare cutting) filter or a 'Pola'-screen is advisable,

f With this combination an exposure about eight times that with Type A film is required.

23

Filters for Colour Separation Processes

FILTERS FOR THREE-COLOUR PHOTOMECHANICAL REPRODUCTIONS

Nos. 25, 58, 47, 9, 0, 29, 61, 49, 33.

Reproducing from flat copy or coloured originals

The standard 'Wratten' set of tri-colour filters consists of a No. 25 (A),a No. 58 (B2), and a No. 47 (C5) filter : these filters are generally referredto in colour work as the A, B and C filters.

The trichromatic inks used for letterpress colour printing cannotthemselves give a perfect reproduction of a coloured original because theseinks do not reflect and absorb different colours just as the theoretical idealrequires. To reduce the resulting imperfections it is usual to prepare afourth printing block from which is printed a grey or black image in exactregister with the colour image; this " black printer," as it is called, is

prepared from a negative of the coloured original which has been exposedthrough a yellow " correction " filter. For this purpose the 'Wratten'No. 9 (K3) filter is supplied and is included in the 'Wratten' Sets of 4 and5 Tri-colour Filters (see below).

The use of glass filters over a camera lens inevitably introduces a slightfocus shift, particularly so when using 'A' quality filters, owing to theextra thickness of glass through which the light must pass. This error,however, is of little consequence in normal photographic work, when it

usually falls within the depth of focus of the lens. When an extremelyaccurate focus is required, however, as when preparing tri-colour negativesfor photo-mechanical reproduction, the camera must be focused with a'Wratten Filter No. in front of the lens. This allows adjustment to bemade to overcome the effect of the slight focus shift introduced by the useof the 'Wratten' Tri-colour Filters. This filter is colourless and in noway interferes with judgment ofcolour values or contrasts. The 'Wratten'Filter No. is included in the 'Wratten' Set of 5 Tri-colour Filters.

'Wratten' Set of 3 Tri-colour Filters : Nos. 25, 58, 47.'Wratten' Set of 4 Tri-colour Filters : Nos. 25, 58, 47, 9.

'Wratten' Set of 5 Tri-colour Filters : Nos. 25, 58, 47, 9, 0.

'Wratten' tri-colour filters, when supplied as a set or when containedin a larger set, are matched optically to ensure accurate registration.

Reproducing from 'Ektachrome' and 'Kodachrome' transparencies

For the preparation of colour separation negatives from 'Ektachrome'and 'Kodachrome' transparencies for reproduction by photomechanicalmethods, the following filters are recommended.

Two-mask method

Separation negatives Nos. 29, 58* and 47Masking Nos. 33 and 58

This method is recommended for use when it is desirable to keep to aminimum the amount of hand-work necessary at later stages in thereproduction process. It is particularly suitable for use when the trans-parency contains much fine detail and when it is essential to retain thephotographic quality of the original transparency during reproduction.

24

The contrast-reducing, colour-correcting masks are applied, in turn,

direct to the original transparency, thus enabling a set of colour-corrected

colour-separation negatives to be prepared straight from the transparency

by either contact or enlargement.

Single-mask method (with additional masking)

Separation negatives Nos. 29, 58* and 47

Masking No. 33

When it is found more convenient to introduce the photographic colour-

correction at the separation negative stage, the single-mask method may be

used. The 'Wratten' Filter No. 33 is used primarily for making the

contrast-reducing mask, the colour-correcting masks being made by

contact from the red and green filter separation negatives.

Single-mask method (without additional masking)

Separation negatives Nos. 29, 61 and 49

Masking No. 33

In certain instances, as when the original transparency contains broad

expanses of colour with little significant detail, full photographic colour-

correction may not be considered necessary. In these cases the No. 33

filter is used primarily for making the contrast-reducing mask and the

Nos. 29, 61 and 49 filters to provide the necessary colour separation.

FILTERS FOR THE 'KODAK' DYE TRANSFER PROCESS

Nos. 25, 58, 47, 29, 61, 49, 33, 2B.

Reproducing from flat copy or coloured originals

For the preparation of three-colour separation negatives from flat copy

or coloured originals for reproduction by the 'Kodak' Dye Transfer

Process, the standard set of 'Wratten' tri-colour filters is recommended.

When supplied as a set, these filters are matched for identical optical

performance to ensure accurate registration.

Reproducing from 'Ektachrome' transparencies

For the reproduction of 'Ektachrome' transparencies by the 'Kodak'

Dye Transfer Process, the two-mask method is recommended for prepar-

ing the separation negatives.

Two-mask method

Separation negatives 29, 61, 49 and 2BMasking 29,61

'Wratten' filters Nos. 29, 61 and 49 plus 2B are recommended for making

the red, green and blue filter negatives, the Nos. 29 and 61 being also used

for preparing the magenta and yellow contrast masks.

Reproducing from 'Kodachrome' transparencies

For making three-colour separation negatives from 'Kodachrome'

transparencies for reproduction by the 'Kodak' Dye Transfer Process the

'Wratten' Narrow-cut Tri-colour filters are again recommended.

Two-mask method

Separation negatives Nos. 29, 61 and 49Masking Nos. 29 and 61

* When the tendency is to over-saturation of reds and magentas in the warm-yellows, the use of a

'Wratten' No. 15 filter is recommended for use in combination with the No. 58 when making the

green separation negative.

25

In most circumstances when it is desired to reproduce accurately therelative brightness values, colour saturation and hues of the original

transparency, the two-mask method ofmaking colour separation negatives

should be employed. Filters Nos. 29, 61 and 49 provide the necessarycolour separation, the Nos. 29 and 61 also being used for preparing thecolour-correcting masks.

Single-mask method

Separation negatives Nos. 29, 61 and 49Masking Nos. 33 or 29

On occasions when a slight shift of hue is considered permissible, thesingle-mask method may be used. 'Wratten' niters Nos. 29, 61 and 49are again used for the colour separation negatives, the No. 33 or theNo. 29 being used to make the mask.

»

'Wratten' Analysis Set for Screen Plates

Nos. 29 (F), 61 (N), 50 (L).

A specially prepared set of three tri-colour niters for the preparation ofthree-colour negatives from additive screen colour transparencies.

'Wratten* Complementary Filter Set

Nos. 44, 32, 12

These three niters, because of their primary absorption, are most usefulfor the visual analysis of additive colour prints and transparencies. Bytheir use, any one of the three colour printings will appear to be completelyremoved, leaving the other two for inspection.

The 'Wratten' No. 12 (Minus Blue) and the 'Wratten' No. 32 (MinusGreen) niters may also be used with advantage in one-shot or repeating-back cameras in tungsten light if, with the use of the normal tri-colourfilter set, the exposures through the green and blue filters are found tobe rather longer than the red. Instead of the tri-colour green filter, the No.12 (Minus Blue) filter can be used with a high-speed orthochromaticmaterial (O.800 plate) ; and instead of the tri-colour blue, the No. 32(Minus Green) filter can be used with the same material. The redseparation can be made as usual using a tri-colour red filter (No. 25) with apanchromatic material (P. 1200 plate). In this way the exposures may bemore evenly balanced.

No.No. 50

Filters for Two-Colour Separation

No. 29 No. 22 No. 15 No. 25 No. 15No. 44 No. 58 No. 49 No. 58 No. 45

For the photomechanical reproduction of illustrations that have beenmade in two colours complementary to each other (so that when the coloursoverlap a grey or black is obtained), special filters are sometimes required.For this purpose six different pairs of niters, complementary to each other,are provided.

These filters enable photo-engravers to cope with any such two-colouroriginals which may arise.

26

NUMERICAL LIST OF FILTERS

The niters in the following list are arranged in numerical order to facilitate

reference. In the first column are shown the numbers and names by

which the niters are known. In the second column is stated the visual

colour of the filter, and in the third column, the purpose for which they

are generally used. Most niters are available in all qualities of glass (see

page 4) but where there are exceptions, these are referred to at the foot

of the appropriate page. The page reference shown in the last column

shows where else in this book further information can be found.

Wratten Numberand Name

1A

2B

3

5

8(K2)

9(K3)

U (XI)

Visual Colour

Colourless

Very faint pink

Colourless

Very light yellow

Light yellow

Yellow

Medium yellow

Light yellow-green

UsePage

Reference

For focusing

Haze filter. Absorbsultra-violet light. Is ofparticular use outdoors

with colour films, pre-

venting excess bluecaused by aerial haze.

Haze filter. Absorbsultra-violet light strongly

For use with black -

and - white film whenused at high alti-

tudes, or at other times

when an excess of ultra-

violet light is present.

Aerial photography.

Aerial photography.

Correction filter. Absorbsultra - violet and someblue. Reproduces colours

in their correct relation-

ship when photograph-ing in daylight.

Correction filter. Absorbsultra - violet and someblue. Tends to over-

correct tones.

Correction filter. Absorbsultra-violet, some blueand slightly more red.

Gives correct rendering

of colours when photo-graphing by tungstenillumination. Reproducesgreens slightly lighter in

daylight.

24,36

11,20,36,82

11, 12,

25, 37,

82

11,37

37

1L 12,

26,38

24,38

11,12,38

27

Wratten Numberand Name

12 (Minus blue)

15(G)

Visual Colour

Deep yellow

Very deep yellow

18A*

18B*

22

23A

25(A)

29(F)

Visually opaque

Very deep violet

Deep orange

Reddish orange

Red

Deep red

30 Light magenta

Use

Complementary filter.

Absorbs ultra-violet andblue. Strong over-correction when usedout-of-doors. Rendersblue in very dark tones.

Strong haze penetration.

Contrast filter. Absorbsultra-violet, blue and asmall amount of green.Gives moderate over-correction to sky whenused in daylight and en-hances detail in brickbuildings, furniture, etc.

Ultra - violet work.Absorbs blue, green andall colours except a verysmall amount of extremered.

Ultra - violet work.Absorbs blue, green andall colours except someextreme red.

Contrast filter. Absorbsultra - violet, blue andsome green.

Contrast filter. Absorbsultra - violet, blue andsome green.

Standard tri-colour filter

for colour separation.Absorbs ultra-violet, blueand green. Gives verystrong over-correction to

sky when used out-of-doors.

Narrow - cut tri - colourfilter for colour separa-tion. Absorbs ultra-

violet, blue and green.Used for making separa-tion negatives from col-

our transparencies.

Contrast filter. Absorbsgreen. Photomicro-graphy.

* Available as a glass filter only. Not in gelatine form.

PageReference

11,26,39

11, 12,

13, 26,

39, 57,

59

11, 12,

14,39,61,82

14, 40,61

11, 12,

13, 14,

26, 40,58

11,40,59

11,12,13, 24,

26, 41,

57,60

11,12,24, 25,

26, 41,60

11,41

Wratten Numberand Name

32 (Minus green)

33

35(D)

36

38

Visual Colour

Magenta

Magenta

Deep magenta

Very deep violet

Light blue

38A

44 (Minus red)

45

47 (C5)

49 (C4)

50

Blue

Light blue-green

Blue-green

Deep blue

Very deep blue

Very deep blue

Use

Complementary filter.

Absorbs green.

Contrast filter. Absorbsgreen. For making colour

masks for colour repro-

duction processes.

Contrast filter. Absorbsgreen and some red andblue. Photomicrography.

Contrast filter. Absorbs

all green, much red andless blue. Photomicro-

graphy.

Contrast filter. Absorbs

some ultra-violet and red.

Corrects the tendency for

reds to reproduce too

light when photograph-

ing in tungsten illumina-

tion using panchromatic

materials.

Contrast filter. Absorbs

a large amount of ultra-

violet and red and somegreen. Photomicro-graphy.

Complementary filter.

Absorbs red and someultra- violet. Photomicro-

graphy.

Contrast filter. Absorbsred, some green and blue

and much ultra - violet.

Photomicrography.

Standard tri-colour filter

for colour separation.

Absorbs red and mostgreen and ultra-violet.

Narrow -cut tri-colour

filter for colour separa-

tion. Absorbs red, green

and much ultra-violet.

Used for making colour

separation negatives fromcolour transparencies.

Contrast filter. Absorbsred, green and muchultra-violet. Photo-

micrography.

PageReference

11,26,42

24, 25,

26,42

11,12,42, 57,

59

11, 12,

43

11,43

13,43

11,26,44

11, 12,

13, 26,

44,57,58, 59,

62

11, 12,

24, 25,

44,57,60,62

11,24,25, 26,45,58

11,14,26,45

28 29

Wratten Numberand Name

54

58 (B2)

59

61 (N)

66

70

72A

72B

73

7475

76*

77*

77A*

78APhotometric bluish

78CPhotometric bluish

80A

Visual Colour

Very deep green

Green

Light green

Deep green

Very light green

Very deep red

Very deeporange-red

Very deeporange-red

Very deepyellow-green

Very deep green

Very deepblue-green

Very deep violet

Deep orange-red

Deep orange-red

Light blue

Very light blue

Light blue

Use

* Available as a glass filter only. Not in gelatine form.

Contrast filter. Absorbsultra - violet, blue andred and some green.Photomicrography.

Standard tri-colour filter

for colour separation.Absorbs ultra-violet, blueand red.

Contrast filter. Absorbssome red and blue.

Narrow - cut tri - colourfilter for colour separa-tion. Absorbs ultra-violet, blue and red.Used for making separa-tion negatives from col-our transparencies.

Contrast filter. Absorbssome red, blue and ultra-violet.

Monochromats.

Mercury - vapour lampmonochromat.

Mercury - vapour lampmonochromat

.

For photometric work.

Correction filter. Forusing ' Ektachrome ' or'Kodachrome* (Daylight-Type) film in Photofloodlight.

PageReference

45

11,12,13, 24,

25, 26,

46,57,58,60

11,46

1 1, 24,

25, 26,

46,59,60

11, 13,

47

11,12,14,

49-47,

62

11, 14,

49

14,50

11,13,15, 50,79

20,51

Wratten Numberand Name

Visual Colour Use

81|

81Ablu

f Balancing81C81EF /

82 \

82A | Light-

82B jBalancing

82CJ

85 Type A 'Koda-chrome' filter for

daylight

85B

86A Photometricyellowish

86C Photometricyellowish

87

88A

90

ND.0.1

ND.0.2

ND.0.3

ND.0.4

ND.0.5ND.0.6

ND.0.7ND.0.8

ND.0.9

ND.1.0

ND.2.0

Pale yellowish

Bluish

Amber

Amber

Yellowish

Yellowish

Visually opaque

Visually opaque

Dark grey-green

Neutral

Used to lower the effec-

tive colour-temperature

of a light-source.

Used to raise the effec-

tive colour-temperature

of a light-source.

Correction filter. Forusing 'Kodachrome'Type 'A' film in daylight.

Correction filter. Forusing 'Ektachrome' Type'B' films in daylight.

For photometric work.

For specialized infra-red

work.

For general infra-red

work.

Monochromatic viewingfilter for visual use in day-

light. Reduces the bright-

ness of colours to assist

judging of tone values.

PageReference

'Wratten' Neutral Den-sity Filters, used for the

controlled reduction of

light intensity.

11,21,51-52,

70,79

11,21,53-54,

70,79

11,20,54,79

11,20,54,79

11,15,55,79

11,63,82

11, 14,

63,82

19,56

11,13,16, 17,

56,61

30 31

Wralten Numberand Name Visual Colour Use

'WRATTEN' COMPOUND FILTERS

Light blue78A + 78A Photo-metric bluish*

78C + 78C Photo-metric bluish*

86A + 86A Photo-metric yellowish*

86C + 86C Photo-metric yellowish*

'KODAK' FILTERS

557/1 Monochro-matic viewing filter*

4t11 t

15 t

25 f

CK.3

CC-05YCC-10YCC-20Y

CC-05MCC-10MCC-20M

CC-05CCC-10CCC-20C

CC-05RCC-10RCC-20R

CC-05GCC-10GCC-20G

CC-05BCC-10BCC-20B

Pola-screen*

Light blue

Light yellow

Light yellow

Dark yellow-green

Yellow

Light yellow-green

Very deep yellow

RedYellow

Yellow

Magenta

Cyan

Red

Green

Blue

For photometric work.

For photometric work.

For photometric work.

For photometric work.

Monochromatic viewingfilter for visual use withaverage tungsten studiofighting.

Correction filter.

Correction filter.

Contrast filter.

Contrast filter.

Correction filter

Colour-compensatingfilters for use in colourphotography.

Neutral grey For reflection control.

* Available as a glass filter only. Not in gelatine form.t Supplied only as a glass filter with metal rim for use in 'Kodak* Lens Attachments.

PageReferenct

19

17,89

17,89

17,90

17,90

17,90

11,22,68-69

11,22,66-67

22,64-65

22,

64-65

22,66-67

22,68-69

18

'WRATTEN9 FILTER SETSBecause 'Wratten' filters are listed in sets it does not necessarily imply

that all components are immediately available from stock. Certain

specialized niters may have to be specially cemented. 'Wratten' filter

sets consist of one of each of the filters named. Standard sizes and

qualities are shown against each set. Sets of glass niters are normally

supplied in 2-inch squares except where otherwise stated. Other sizes

up to a maximum of 4 inches can usually be supplied to special order.

The Laboratory Sets of 24 and 50 niters are supplied in finely polished

mahogany cases complete with lock and key: other sets of filters cemented

in "B", "Cine" or "D" quality glass, are supplied complete in stiff,

covered, card cases.

All filter sets supplied in "A" quality glass are supplied in leather

covered cases lined with silk and velvet.

•Wratten' Technical Set

of 8 Filters

'Wratten* Set of

Photometric Filters

'Wratten' Laboratory Set

of 50 Filters

Nos. 3, 8, 11, 15, 25, 29, 47, 58.

Normally supplied in "B" quality glass.

Other qualities available to special order.

Nos. 78A+78A, 78A, 78C+78C, 78C,86A+ 86A, 86A, 86C+86C, 86C.

Normally supplied in "B" quality glass.

Other qualities available to special order.

Nos. 1A, 2B, 3, 8, 11, 12, 15, 18A, 22, 23A, 25,

29, 30, 32, 35, 36, 38, 44, 45, 47, 49, 50,

58, 59, 61, 66, 70, 72B, 73, 74, 75, 76, 77,

78A, 78C, 81, 81EF, 82, 85, 85B, 86A, 86C,87, 88A, CC-20Y, CC-05M, ND.0.1,ND.0.2, ND.0.5, ND.0.8.

Normally supplied in "B" quality glass

(except 18A). Available in "A" or "Cine"

quality glass to special order. Supplied

complete in fitted mahogany case.

32

'Wratten' Laboratory Set Nos. 2B, 8, 11, 12, 15, 22, 25, 29, 32, 35, 44, 45,

0T24 Fitters*

ft*58

>59

> « 70>72B

>73

>74

>75

'76'

Normally supplied in "B" quality glass.

Other qualities available to special order.

Supplied complete in fitted mahogany case.

33

•Wratten' M Set of 9 Filters Nos. 1 1, 15, 22, 25, 29, 35, 45, 47, 58.

for Microscopy Available in "D" quality glass only.

•Wratten* Visual M Set

of 9 Filters

Nos. 15, 22, 25, 38A, 45, 58, 66, 78A, ND.1.0.

Normally supplied in If in. diameter circles

in "D" quality glass only.

'Wratten' Spectroscopic

Set of 8 Filters

Nos. 2B, 8, 15, 18A, 25, 29, 36, 70.

Normally supplied in "B" quality glass

(except 18A). "D" quality glass available

to special order only.

'Wratten' Mercury Mono- Nos. 22, 50, 74.

chromatic Set of 3 Filters Available in "D" quality glass only.

'Wratten' Monochromatic Nos. 70, 72B, 73, 74, 75, 76, 88A.

Set of 7 Filters Normally supplied in "B" quality glass.

Other qualities available to special order.

'Wratten' Analysis Set

for Screen Plate

Nos. 29, 50, 61.

Normally supplied in "B" quality glass.

Other qualities, except "D" quality, avail-

able to special order.

'Wratten' Complementary Nos. 12, 32, 44.

Filter Set Normally supplied in "B" quality glass.

Other qualities available to special order.

'Wratten' Standard Nos. 25, 58, 47.

Tri-colour Sets of 3, 4 and gos. 25, 58, 47, 9.

5 FiltersNos

'

25'58, 47, 9

'0l

Supplied either in gelatine form or cemented

in "B" quality glass. Other qualities to

special order.

'Wratten* Narrow-Cut Nos. 29, 61, 49.

Tri-colour Set of 3 Filters Normally supplied in gelatine form. Avail-

able cemented in glass to special order.

34

SPECTROPHOTOMETRY ABSORPTIONCURVES AND DATA

The absorption curves, as determined by spectrophotometric measure-

ments, are plotted as curves of density against wavelengths, all wavelengths

being expressed in terms of millimicrons (ma), one ma being equal to

0.000001 millimetre. Where the spectrum extends into the ultra-violet,

the absorption has been determined either photographically or photo-

electrically in a quartz spectrophotometer. On referring to these curves

the transmission of light of any colour can be determined. For the filter

No. 58 for instance, it will be seen that at the bottom of the curve, that

is, at wavelength 530 ma, this filter has a density of slightly less than 0.3,

indicating that the filter transmits rather more than one-half of the incident

light of this colour. In the table, the transmission at 530 ma is also

given as 53.6 per cent. At a wavelength of 579 ma the filter has a density of

1 and therefore transmits 10 per cent of the light of this colour (and also

of the colour indicated by the wavelength 495 ma, as shown at the other

side of its transmission curve); similarly, the transmission drops to

approximately 1 per cent, at wavelengths 479 and 605 ma.

Transmission in the ultra-violet at wavelengths less than 330 ma will

be eliminated in the case of cemented niters, as glass absorbs ultra-violet

radiation of wavelengths shorter than 330 ma, as shown in the first

absorption curve on page 36.

In addition to the percentage transmission at each wavelength, the

tables give for each filter in the 'Wratten' range, the total visual transmis-

sion factor V, and the chromaticity co-ordinates x and jy, based on the

data for the Standard Observer, adopted by the Commission Internationale

de l'Eclairage (CLE.) in 1931. The chapter on "Colour Specification" on

page 71 gives an explanation of the CLE. system and the meaning of the

terms employed. The values YA, *A, and vA are for the CLE. standard

illuminant "A", which has a colour temperature of 2854° K; the values

yc, xc andyc are for the CLE. standard illuminant "C", which represents

a mixture of sunlight and skylight and is approximately similar to the light

from a source of colour temperature 6,500° K. The positions of the

filters in the 1931 CLE. chromaticity chart are shown for these two

illuminants on pages 74 to 77.

These values of Y, x and y given in the tables were determined for

the Kodak standard filter gelatines but, owing to certain small un-

avoidable variations, the figures given may vary slightly for particular

samples. If, therefore, niters are required for extremely accurate work,

they should be calibrated individually.

35

IA 2B

Mt

i «i • ibLIllUUk

Two "B" glasses cemented together

imriilitliijI

::::::::::LB**

Ji

.ia

'

i

IA

The tables show percentage transmittance values forwavelengths from 400 (o 700 m\i. The total visualtransmittance is provided by the Ya value (artificiallight) and the Yc value {daylight).

36

88.0 59.0 400

88.5 76.0 10

88.9 82.0 20

89.3 84.6 30

89.6 86.0 40

89.8 86.8 50

89.9 87.2 60

90.1 87.5 70

90.3 87.3 80

90.4 86.8 90

90.5 86.3 500

90.6 85.5 10

90.7 84.8 20

90.7 84.3 30

90.8 84.0 40

90.8 83.9 50

90.9 84.1 60

90.9 84.8 70

90.9 86.0 80

91.0 87.4 90

91.0 88.5 600

— 91.0 89.5 10

91.0 90.2 20

91.0 90.6 30

91.1 90.8 40

91.1 91.0 50

91.1 91.1 60

91.1 91.1 70

91.1 91.1 80

91.1 91.1 90

91.1 91.1 700

.4484

— .4080

.4524

.4042

.909 .865 Ya

.3112

— .3117

.3132

.3147

.908 .859 Yc

"400 19.0 — —10 48.0 — —20 67.0 — —30 75.3 0.36 —

"40 80.0 1.78 —50 83.0 11.5 —60 85.2 33.0 —70 86.7 68.0 1.60

80 88.1 80.8 12.0

90 88.8 85.2 32.3

500 89.5 86.9 56.5

10 89.9 87.8 72.0

20 90.3 88.4 81.0

30 90.5 89.0 84.6

40 90.6 89.5 86.4

50 90.7 89.8 87.4

60 90.8 90.1 88.0

70 90.9 90.4 88.5

80 90.9 90.6 88.9

90 91.0 90.7 89.1

600 91.1 90.8 89.4

10 91.2 90.9 89.7

20 91.3 91.0 90.1

30 91.3 91.0 90.3

40 91.4 91.1 90.5

50 91.4 91.2 90.7

60 91.5 91.3 90.9

70 91.5 91.4 91.1

80 91.6 91.5 91.3

90 91.7 91.6 91.4

700 91.8 91.7 91.5

*A

>A

.4526

.4126

.4803

.4470

.517

.462

J*A .908 .897 .835

xc .3178

.3298

.3752

.4382

.443

.512

mYc .905 .883 .809

lllllllll11

BBBBBBBBIBill9BHMHH1

iHIISBHHMBCHtfBKant laafllL

2B

III!BHItk^ftfBBBB

H1B! 1 •» ! !*!^HHKi!!• .

inilKilflilHHBWBl!

BBBBBBBBBBBBBIa[]«[i.«!»» 1 ^ !&*»h*" IfiBlBBBBI

BBBBBBBBBBBBBBi

1

01*

The tables show percentage transmittance values for

wavelengths from 400 to 700 m\j.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

37

Billseii

::

8!I1HBHHHBHBI«IM! !«ii

100 100 503 MO 700

1

10-:

300 400 500 MO 700

2

10*

100 100 400 SOO MO

II

The tables show percentage transmittance values forwavelengths from 400 to 700 m\x. The total visualtransmittance is provided by the Ya value {artificiallight) and the Yc value (daylight).

38

89.2

8 9 II

— — — 46<r— — —

10

— — 0.16 20

— — 0.29 30

— — 0.56 40

— — 1.32 50

0.25 — 4.00 60

5.50 1.78 12.0 70

19.0 8.31 26.0 80

41.0 20.7 43.7 90

63.5 34.5 55.0

78.0 48.8 60.0 10

84.1 62.0 60.2 20

86.5 76.0 57.8 30

87.7 83.8 54.2 40

88.4 87.0 50.0 50

88.8 88.3 44.8

12 15 I8A

~400 — — —10 — — —20 — — —30 — — —

- 40 — — —50 — — —60 — — —70 — — —80 — — —90 — — —

SOO 1.50 — —10 17.3 1.00 •

—20 55.0 16.0 —30 77.8 52.1 —40 86.0 70.7 —50 88.4 84.3 —60 89.4 87.5 —70 89.7 88.7 —80 90.1 89.3 —90 90.3 89.7 —

600 90.4 90.0 —10 90.5 90.1 —20 90.7 90.2 —30 90.8 90.3 —40 90.9 90.4 —50 91.0 90.5 —60 91.1 90.6 —70 91.2 90.6 —80 91.2 90.7 —90 91.2 90.7 0.25

700 91.3 90.8 1.20

Va

.5331

.4610

.5494

.4473

—

*4 .812 .752 —*c .4825

.5083

.5058

.4895

—

Yc..738 .662 —

400 SOO MO TOO

12IIIM!!»§MP** *§!»»tHIHUUI IUMJ

I ox

300 400 500 400 7N

15

2W 300 400 SOO MO 700

I8A

The tables show percentage transmittance values for

wavelengths from 400 to 700 mu.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

39

Iina!_I IBB

IBBBBBBBI8BBBBBBBBBBBBII

00 500 600 70IIIIIaaa:::::::::::::::ueSKSiBMSiiKiBBk. 100*

22

23A

The tables show percentage transmittance values for

wavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

40

I8B 22 23A

39.9 — — 400

10.5 — — 10

4.00 — — 20

1.00 — — 30

— — — 40

— — — 50

— — — 60

— — — 70

— — — 80

— — — 90

— — — 500

— — — 10

— — — 20

— — — 30

— — — 40

— 0.25 — 50

— 19.0 — 60

— 60.0 11.0 70

— 81.0 47.0 80

— 87.0 69.6 90

— 88.5 82.7 600

— 89.0 85.8 10

— 89.5 87.2 20

— 89.8 87.9 30

— 90.0 88.5 40

— 90.1 89.0 50

0.10 90.2 89.4 60

0.70 90.3 89.6 70

5.30 90.4 89.8 80

17.8 90.5 90.0 90

33.1 90.6 90.2 700

—.6214

.3780

.6498

.3498 :yA

— .482 .363 YA— .6030

.3964

.6386

.3610

— .358 .250 Yc

25 29 30

400 — — 48.6

10 — — 47.4

20 — — 48.5

30 — — 50.1

- 40 — — 49.4

50 — — 43.0

60 — — 26.5

70 — — 13.8

80 — — 5.00

90 — — 0.63

500 — — —10 — — —20 — — —30 — — —40 — — —50 — — —60 — — 0.10

70 — — 10.0

80 — — 45.0

90 12.6 — 76.0

600 50.0 — 87.4

10 75.0 10.0 89.5

20 82.6 45.3 90.2

30 85.5 71.4 90.5

40 86.7 82.7 90.7

50 87.6 86.6 90.8

60 88.2 88.4 90,9

70 88.5 89.4 91.0

80 89.0 90.0 91.1

90 89.3 90.3 91.1

700 89.5 90.4 91.1

*A

-yA

.6850

.3147

.7116

.2883

.6023

.3175

Ya .225 .110 .378

.6808

.3190

.7102

.2898

.4520

.2270

l'c .140 .630 .266

IJBBBBBBBBBI•BBBI»IBBBBBBBBBBIIBBBBBBBBBBIIBBBBBBBBBBIIBBBBBBBBBBI

100 100 400 500 MO 700

25

OIX

The tables show percentage transmittance values for

wavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

41

32

** s HaK At'h l_

:s:e;;sss:;s: mnzl

33

35

The tables show percentage transmittance values forwavelengths from 400 to 700 m^. The total visualtransmittance is provided by the Va value (artificial

light) and the Yc value (daylight).

42

32 33 35

38.0 0.85 48.0 400

37.9 0.71 57.0 10

40.0 1.17 57.6 20

43.0 1.69 47.5 30

55.5 5.36 29.5 40

66.0 14.3 12.3 50

66.0 12.4 3.50 60

57.0 5.00 0.25 70

40.0 0.50 — 80

21.0 — — 90

9.56 — — 500

2.51 — — 10

0.13 — — 20

— — — 30

— — — 40

— — — 50

— — — 60

— — — 70

— — — 80

— — —t

90

6.04 — — 600

41.0 0.80 — 10

75.0 24.9 — 20

86.1 60.8 — 30

89.0 78.0 — 40

90.0 85.0 0.10 50

90.6 87.5 3.00 60

90.7 88.7 19.0 70

90.8 89.4 43.5 80

90.9 89.8 66.0 90

91.0 90.0 77.7 700

.5410

.2281

.6733

.2641

.300

.071

.169 .088 .0053 YA

.3079

.1179

.5198

.1947

.1818

.0174

xc

yc

.125 .052 .0045 yc

36 38 38A

400 36.5 60.5 33.4

10 45.5 66.5 41.2

20 45.5 72.5 53.0

30 32.7 75.3 58.0

40 15.2 76.2 58.8

50 3.70 75.9 57.6

60 0.35 74.8 55.2

70 — 73.4 51.9

80 — 71.6 48.5

90 — 69.5 44.6

500 — 66.7 40.2

10 — 63.9 35.8

20 — 60.8 31.7

30 — 57.0 27.2

40 — 52.6 22.3

50 — 48.0 17.6

60 — 42.8 12.9

70 — 37.0 8.78

80 — 30.6 5.65

90 — 25.5 3.48

600 — 20.9 2.09

10 — 16.8 1.15

20 — 12.9 0.59

30 — 10.0 0.28

40 — 7.79 0.13

50 — 6.68 —60 0.21 6.20 —70 7.50 5.91 —80 29.0 5.41 —90 55.0 4.90 —

700 70.3 5.00 —XA

3»A

.316

.076

.3062

.4038

.1934

.3263

Ya .0034 .361 .126

*c

yc

.1862

.0165

.2122

.2583

.1606

.1796

Yc .0025 .425 .173

!SHUttUUt

kl—MM—200 300

imnn400 500 400 TOO

38

The tables show percentage transmittance values for

wavelengths from 400 to 700 mjx. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

43

h--*44

joo ioo 600 700

45

mmam* ]!i tAmmm!a r !» I. a

c 1IIIII 1IKMIHMIfa

j

!iili t

SlMHIIIIIII!200 100 400 500 600 700

47

The tables show percentage transmittance values forwavelengths from 400 to 700 m\j.. The total visualtransmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

44

44 45 47

0.44 — 7.80 400

0.36 — 17.4 10

0.63 — 34.0 20

3.63 — 47.0 30

13.1 5.00 50.3 40

25.4 19.0 48.3 50

36.5 29.5 43.4 60

46.5 34.4 36.2 70

53.6 35.7 28.5 80

56.8 34.5 19.6 90

55.8 29.7 11.3 500

50.9 21.5 5.64 10

42.1 11.5 1.91 20

30.5 3.80 0.36 30

18.6 0.85 — 40

8.99 — — 50

3.59 — — 60

0.80 — — 70

— — — 80

— — — 90

— — — 600

— — — 10

— — — 20

— — — 30

— — — 40

— — — 50

— — — 60

— — — 70

— — — 80

0.18 — — 90

1.60 1.00 — 700

.1236

.4126

.0998

.2451

.1371

.0724

.103 .028 .012 Ya

.1200

.2807

.1108

.1692

.1451

.0485

.156 .052 .028 YC

49 50 54

1% —

"loo 3.30 0.45 —10 4.28 0.39 —20 6.93 0.59 —30 11.2 2.63 —40 18.9 8.90 —50 25.6 14.0 —60 24.0 12.3 —70 15.7 5.36 —80 6.93 1.55 —90 2.14 0.10 —

500 0.46 — —10 — — 0.10

20 — — 0.31

30 — — 0.64

40 — — 0.89

50 — — 0.93

60 — — 0.62

70 — — 0.21

80 — — —90 — — —

600 — — —10 — — —20 — — —30 — — —40 — — —50 — — —60 — — —70 — — —80 — — —90 — — —

700 — — —

3-a•

.1457

.0353

.1488

.0279

.2829

.6997

YA .0022 .00079 .00027

*c .1491

.0299

.1509

.0254

.2746

.7060

Yc .0069 .0026 .00032

IBa,miit*Mku*

8* ^r-]S0 300 tOO 500 M0 '00

49

I!1"

II!:::::::::=£:::::::::!.;•jil!l!! 4ffiW1UUIU1IIU1III1I

200 300 400 S00 600 700

50

(aBaus

J00 300 100 50fl

«54

The tables show percentage transmittance values for

wavelengths from 400 to 700 m\x. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

45

58

!!»*•**•* iwmmaaBMBmmMwwmm

BBBBlk A !»««

100 ]00 400 S00 600

59

::::::::::::::::::::::::::::

:::

200 — 300 SOO too

61

The tables show percentage transmittance values for

wavelengths from 400 to 700 my. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

46

58 59 61

— — — 4<HT

— — — 10

— — — 20

— — — 30

— — — 40

— 0.40 — 50

— 1.90 — 60

0.23 7.70 — 70

!.38 21.3 0.33 80

4.90 41.5 4.00 90

17.7 59.0 16.6 500

38.8 67.7 32.3 10

S2.2 69.8 40.0 20

53.6 67.2 39.6 30

47.6 61.5 34.5 40

38.4 54. 26.3 50

27.8 45.0 17.3 60

17.4 35.0 9.70 70

9.0 24.0 4.40 80

3.50 14.0 1.66 90

1.50 7.95 0.38 600

0.41 4.90 — 10

— 2.70 — 20

— 1.00 — 30

— 0.17 — 40

— — — 50

— — — 60

— 0.63 — 70

— 4.00 — 80

— 12.0 — 90

0.53 22.6 — 700

.2693

.6831

.3028

.6118

.2457

.6989

*A

^A

.198 .326 .137 **

.2425

.6923

.2507

.6023

.2213

.7053

xc

yc

.237 .387 .168 Yc_

66 70 72A

400 12.3 — —10 13.0 — —20 15.0 — —30 18.4 — —

^ 40 23.2 — —50 31.2 — —60 42.2 — —70 55.5 — —80 68.4 — —90 77.6 — —

500 82.7 — —10 84.6 — —20 84.0 — —30 82.6 — —40 79.1 — —50 73.7 — —60 67.1 — —70 58.8 — —80 47.2 — —90 34.5 — 5.75

600 24.4 — 16.2

10 18.5 — 18.5

20 13.7 — 13.1

30 7.70 — 6.05

-10 3.00 — 2.52

50 1.46 0.63 1.59

60 1.91 10.5 4.18

70 6.17 35.0 16.0

80 19.9 55.2 37.5

90 42.6 70.0 60.0

700 63.1 69.0 75.0

*A

-Va

.3333

.5050

.7331

.2668

.665

.335

^A .506 .0068 .0431

XC

yc

.2486

.4169

.7328

.2672

.658

.341

*ff.583 .0031 .028

100 300 «00 500

66

!a!iiiiiiiniiiiiiiiiiiiiFBIII

•iiiiiiiiiianlUUIIUIllli

2

10%

300 300 400 500 600 '00

70

sft:::::::::::::::::!s:is:::ss:s:s:::s:|:-|:

::::;;::;: ;:s::::::£::'.i:::::::: is:M-—M—MMMMMMMMMill

200 300 400 500 600 '00

72A

The tables show percentage transmittance values for

wavelengths from 400 to 700 my. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

47

riiiiiiian:

!

200 300 400 500 600 700

72B

! —pnran

! :in ibcbbI Iin ii i i

!3BUlHHI« s

!I200 300 400 500 600 700

73

!! ,oo,200 300 400 500 600 700

74

The tables show percentage transmittance values forwavelengths from 400 to 700 my.. The total visualtransmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

48

72B 73 74

— — — 400

— — — 10

— — — 20

— — — 30

— — — 40

— — — 50

— — — 60

— — — 70

— — — 80

— — — 90

— — — 500

— — 0.96 .0

— — 7.95 20

— — 14.6 30

— — 12.9 40

— — 7.60 50

— 2.24 3.06 60

70— 5.97 0.83

— 4.56 0.12 80

1.26 2.00 — 90

5.89 0.56 — 600

5.25 0.10 — 10

2.88 — — 20

1.26 — — 30

0.48 — — 40

0.14 — — SO

— — — 60

— — — 70

— — — so

— — — 90

— — — 700

.6506

.3490

.4853

.5134

.2301

.7421

*A

.0109 .0141 .0334 Y>

.6481

.3515

.4780

.5208

.2227

.7473 yc

.0074 .013 .040 *V

75 76 77

400 — 0.22 —10 — 0.18 —20 — 0.29 —30 — 1.33 —

*" 40 — 3.50 —50 — 3.50 —60 1.97 1.92 —70 10.0 0.51 —80 17.4 — —90 18.0 — —

500 13.0 — —10 7.35 — 0.30

20 3.20 — 9.10

30 0.83 — 13.5

40 0.14 — 46.1

50 — — 78.0

to — — 75.8

70 — — 8.00

30 — — 1.00

90 — — 0.32

600 — — 16.2

10 — — 52.1

20 — — 83.0

30 — — 84.9

40 — — 88.1

50 — — 89.8

60 — — 89.8

70 — — 85.5

80 — — 76.1

90 — 0.13 75.0

700 — 1.24 86.5

*A

-Va

.0732

.3139

.1628

.0220

.5715

.4254

Y* .0101 .000146 .368

xc

-V'c

.0801

.2542

.1578

.0181

.5099

.4854

^c .019 .00046 .323

imnmniin!»!1

ill1 -

j 4 4 ii easfliifi

S«&!!IEiiua

75

VERSESu„m

ui

is:::!!!!&I00 300 400 S00 600 7M

76>i m\—

r

j i-i! !»1 iiii _

j[ _II iiI H -

r-i-;61 ! »*«I III

pai * - in ItjLflMJJJil100 400 500 6O0

77

The tables show percentage transmittance values for

wavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

49

IBBBBBBBBBBBI[I JIBibbbbbbbbbbbm . liBIBBBBBBBBBBBBBI(ei fi*his'!.Bii.niiI IB1 IBI

IBBBBBBBKBBBBBBPilSIXBHIIIII _. _

UMUUMMMMMMMMMMkMMl

*^I*

10.;

77A

nr

i

It

k

IHBBIIBk ^ gi—m II I HII!B

i i1 1 1

II 1 1I1

loo loo 500 600

78A

It

IBBB

U-UHUB* .....

2

io-.c

500 600

78C

The tables show percentage transmittance values forwavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

77A 78A 78C

— 56.0 74.9 4o<r— 58.6 76.6 10

— 61.0 77.9 20

— 61.8 78.9 30

— 61.8 79.4 40

— 61.0 79.5 50

— 58.7 79.3 60

— 55.0 78.6 70

— 51.0 77.8 80

— 47.1 76.7 90

— 43.5 75.5 500

0.10 40.0 74.2 10

5.35 36.9 73.0 20

1.90 34.4 72.1 30

35.0 32.7 71.5 40

71.8 31.2 70.7 50

63.1 29.4 69.8 60

— 28.0 69.0 70

— 27.5 68.8 80

— 27.0 68.6 90

1.60 26.0 78.0 600

32.1 24.1 66.1 10

78.0 21.8 65.0 20

79.5 19.7 63.8 30

86.5 18.6 63.0 40

89.2 18.4 62.7 50

89.0 18.5 63.0 60

79.5 18.7 63.3 70

62.5 19.0 63.4 80

62.4 19.3 63.6 90

83.0 20.2 65.0 700

.5832

.4143

.3715

.3736

.4330

.4044 y*

.294 .291 .692 Y*

.5208

.4753

.2418

.2406

.2954

.3039 yc

.255 .308 .316 Yc

80A 81 8IA

400 67.6 77.7 65.1

10 73.1 78.1 65.9

20 76.8 79.0 67.6

30 77.7 80.5 70.2

*"40 76.5 81.9 72.8

50 73.0 83.0 74.8

60 69.0 83.7 76.0

70 63.6 84.3 77.1

80 57.6 84.6 77.8

90 51.3 84.9 78.3

500 45.2 85.3 78.6

10 39.4 85.4 79.0

20 34.2 35.5 79.5

30 30.0 86.0 80.4

40 27.1 86.5 81.5

50 24.8 86.8 82.3

60 23.5 87.0 82.6

70 22.6 87.1 82.7

80 22.6 87.1 82.8

90 23.2 87.4 83.1

600 23.7 87.6 84.0

10 23.2 88.1 85.0

20 21.0 88.8 86.1

30 IS.2 89.2 87.0

40 15.3 89.4 87.4

50 14.5 89.5 87.7

60 13.8 89.8 88.0

70 13.4 90.0 88.2

80 12.7 90.1 88.5

90 11.7 90.3 89.0

700 11.5 90.5 89.2

*A

3>A

.352

.336

.4522

.4089

.4573

.4102

*M .250 .872 .829

XC

yc

.2229

.2014

.3154

.3218

.3213

.3275

Yc .284 .868 .820

IBIHI

IBBBIi![

IBBBB18BBBHBBBBBB1ZB&miVBB ^i --

AMI " BB BBrrrr

--.*m iii;

80A

BBBBIBBBBI

lis:ssss;IBBBIBBBfll9BBBI 1

HiiiLIBBBI

i

IBBBI Bl*_BBBBIIBJUU1

BBBBImu iSSSSiiiiiiinn

Note density scale extends only to 0.75.

A graph of the 81 series is on page 70.

7$|

o-s

IBBBIIBBBIBBBIBBBI

1

IBBBIITX IBBBISSSKi

075

BflBBBBL Jdh..

1888888! !«'(BBBBflflUUteSSmwl3

Note density scale extends only to 0.75.

A graph of the 81 series is on page 70. 8IA

The tables show percentage transmittance values for

wavelengths from 400 to 700 m\i. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

50 51

_

sbb:iiim

p

a 9M

iff L ^

abb£*dJ_!iiiiL.

200 300 400 500 600 00

8IBNote density scale extends only to 0.75.

A graph of the 81 scries is on page 70.

1

25

nn 'KPi in

1>illsitllfBBBBtBBBBBB 4-bkBK ii k!! ''-Bill! BBBBlffl Rl -,IBBIaUI1UI1IIIIIIIII Si1 I ii00 100 400 s . 00

Note density scale extends only to 0.75.

A graph of the 81 series is on page 70.

namieibuBBBIIBBBIIBBBB ,Jft. laJ

cbbb»i:*«bbbb

l»IISiiSl||l .•

BBBB al 'IBn

k.

BB aia1IBBIBBIBB

Bs:BIBBBB IB IV

BBBBUUUI

k1200 300

8IEFNote density scale extends only to 0.75.

A graph of the 81 series is on page 70.

The tables show percentage transmittance values forwavelengths from 400 to 700 mu.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

52

8IB 8IC 8IEF

55.1 46.1 30.7 400

55.8 46.6 31.5 10

57.7 49.0 34.3 20

61.0 52.5 38.6 30

64.5 57.2 43.2 40

67.2 60.5 47.4 50

69.1 63.0 50.2 60

70.6 64.2 52.0 70

71.3 65.0 53.0 80

71.8 65.7 54.0 90

72.6 66.4 55.4 500

72.9 66.5 56.2 10

73.2 67.0 57.0 20

74.5 68.8 59.5 30

76.0 71.0 62.7 40

77.0 72.0 64.5 50

77.6 72.5 65.3 60

77.8 72.7 65.8 70

78.0 73.0 66.0 80

78.2 74.0 66.5 90

79.1 75.6 68.1 600

81.0 78.5 71.6 10

83.1 80.8 74.7 20

84.2 82.1 77.0 30

85.1 83.0 78.4 40

85.6 83.5 79.2 50

86.0 84.1 80.1 60

86.5 84.8 80.9 70

87.0 85.5 81.8 80

87.5 86.1 82.9 90

88.0 86.8 84.0 700

.4620

.4108

.472

.406

.482

.408

*A

.781 .722 .648 Y*

.3266

.3322

.769

.3330

.3365

.720

.3473

.3500

.640

yc

Yc

82 82A 82B

400 83.0 80.1 76.7

10 83.7 80.8 78.0

20 84.6 81.6 79.2

30 85.1 82.2 79.7

^40 85.4 82.4 79.7

50 85.4 82.4 79.2

60 85.0 81.7 78.0

70 84.6 80.7 76.3

80 84.0 79.3 74.4

90 83.3 78.0 72.1

500 82.6 76.6 70.2

10 82.0 75.3 68.3

20 81.4 74.0 663

30 81.0 73.1 653

40 80.8 72.7 65.0

50 80.6 72.4 64.5

60 80.4 71.8 63.8

70 80.2 71.5 63.2

80 80.2 71.5 63.2

90 80.3 71.7 63.4

600 80.2 71.5 63.0

10 79.3 70.3 61.5

20 78.4 68.5 59.0

30 773 66.9 56.9

40 76.8 65.5 55.0

50 76.5 64.8 54.1

60 76.2 64.6 53.7

70 76.1 64.5 53.7

80 76.1 64.4 53.5

90 76.2 64.2 53.4

700 77.1 64.6 54.1

*A

Va

.446

.401

.439

.398

.431

.395

YA .785 .701 .620

xc

Vc

.3040

.3104

.2970

.3026

.2893

.2937

Yc .807 .725 .646

ibbbtBBBiBflfllBBBIBBBIBBBIBBBI

k.

-•**** BBBBBBBfcliC 9191 Iflk _«• •BB!BBBBBBBBBB

BB00 300 400 S00 600 700

Note density scale extends only to 0.75.

A graph of the 82 series is on page 70.

pmrrBBBIBBBIBBBIBBBIBBBI

1BBBI

o

0-25

BBflBLBllllllnisbbbbB *.«

Note density scale extends only to 0.75.

A graph of the 82 series is on page 70. 82A

fi+HIBBBI! —

£ |

ii M

O BBBI,! LL025* .mmBBBBBBBPBBttUiCBBBBBBB

| !! BB

"51

n

bbbSSbSSBBBI II 1 IBBBI

200 300 400 500 600 n

Note density scale extends only to 0.75.

A graph of the 82 series is on page 70. 82B

The tables show percentage transmittance values for

wavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

53

^ <!

i* *£ IL1 *» ,! 1BIA ^«.&! d IIIIti

II

te._ 4 11 1!lllll

11 !!I 882C

Note density scale extends only to 0.75.A graph of the 82 series is on page 70.

UHHHI1««»*91I2II:tmrnme menu» - !*.« BftlTOlUf 1

i

200 J00 400 $00 tOO 700

85

nnnnn

iS

E*The tob/es show percentage transmittance values for

wavelengths from 400 to 700 mjx. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

82C 85 85B

73.4 6.0 1.59 400

75.0 18.0 9.32 10

76.4 28.4 15.5 20

77.2 33.4 19.0 30

77.2 36.2 20.8 40

76.6 38.1 22.1 50

75.2 40.4 24.3 60

73.2 43.0 27.5 70

70.7 45.3 30.9 80

68.1 47.2 34.3 90

65.7 48.9 38.3 500

63.5 49.2 40.7 10

61.5 48.2 40.6 20

59.9 48.3 40.7 30

59.1 49.2 41.6 40

58.3 51.0 43.2 50

57.2 55.8 47.1 60

56.2 64.5 56.0 70

56.1 75.0 68.1 80

56.0 83.0 78.1 90

55.0 87.2 85.0 600

53.0 88.9 88.0 10

50.2 90.0 89.6 20

47.4 90.5 90.3 30

45.2 90.7 90.7 40

44.1 90.9 90.9 50

43.6 91.0 91.0 60

43.5 91.0 91.2 70

43.1 91.0 91.3 80

42.8 91.0 91.3 90

43.5 91.0 91.3 700

.421

.393

.516

.399

.5353

.4047

*A

3»A

551 .670 .623 YA.2801

.2860

.3861

.3534

.4247

.3805 .Vc

.581 .625 .555 yc.

86A 86C

400 8.00 44.0 —10 12.2 55.0 —20 16.7 62.0 —30 21.5 66.6 —40 27.8 70.8 —50 34.2 74.3 —60 40.4 76.8 —70 45.0 78.7 —80 48.7 80.2 —90 51.2 81.2 —

500 52.8 81.7 —10 53.4 81.8 —20 S3.7 82.0 —30 55.0 82.4 —40 56.5 83.0 —50 58.5 83.5 —60 63.0 84.6 —70 70.9 86.8 —80 79.0 88.9 —90 85.2 89.9 —

600 88.1 90.6 —10 89.3 91.0 —20 90.5 91.1 —30 90.8 91.2 —40 91.1 91.3 —50 91.2 91.4 —60 91.3 91.5 —70 91.4 91.6 —80 91.4 91.6 —90 91.5 91.6 —

700 91.5 91.6 —*A

•Va

.5083

.4132

.4618

.4112 —

Ya .722 .868 —.3849

.3757

.3270

.3330 —

Yc .671 .854 —

J««II:s: :::;!IUMW iu

2

10%

86A

*I !!Ik!.liJBMMBM

|I ox

86C

NO VISUAL TRANSMISSION 87

BETWEEN 400 and 700 mp

SEE PAGE 63 88A

The tables show percentage transmittance values for

wavelengths from 400 to 700 my.. The total visual

transmittance is provided by the Ya value (artificial

light) and the Yc value (daylight).

54 55

a£I 1 '!BHBBUa,_,-a immm

11 .g&BBbiRi imeM'MMnmt , leillllillllllllLilllllIU

90

01%

110*

NDI.O

The tob/es show percentoge tronsmittonce vo/ues forwavelengths from 400 to 700 mp. The toto/ v;'suo/

trensm/ttance Is provided by the Y& value (artificial

lighi) and the Yc value (daylight).

90 NDI.O

— — 4.28 400

— — 4.9! 10

— — 5.50 20

— — 6.17 30

— — 6.92 40

— — 7.50 50

— — 7.81 60

— — 8.15 70

— — 8.47 80

— — 3.60 90

— — 8.73 500

— — 8.85 IC

— — 8.90 20

— — 9.01 30

— — 9.07 40

— — 9.20 50

— 9.00 9.30 60

— 30.5 9.20 70

— 34.3 9.19 80

— 25.2 9.54 90

— 16.1 9.64 600

— 11.3 9.73 10

— 7.40 9.56 20

— 2.94 9.27 30

— 0.76 9.10 40

— 0.29 9.07 50

— 0.41 9.00 60

— 2.30 9.13 70

— 9.52 9.08 uo

— 28.5 9.21 90

— 51.9 9.52 700

—.5484

.4507

.4602

.4170

— .116 .092 y.

— .5329

.4662

.3286

.3430

— .980 .0910 Yc

.SSBSSSBBSBSBSBSSSSSSSSa00 300 400 &00 600 '00

45 + 47I!IHIWHBIIIIIHHI !JHII—mm i«r-(L *!(^ii^JiBJ till!

500 400

15 + 58

I!!# dj m IBH _ _nil!!!! —

«" '555555!ai:

-!»*J00 400 500 400 HKi

25 + 35

The curves show the transmittance of certain pairs of

filters. The combined transmittance value for anygiven wavelength can be calculated by multiplying

together the separate percentage values and dividing

by 100.

5657

4BBBBMBBBBBB IIBBBBBBI

BBM_LJ|IbBBBBIwblTjbbmbsbii jbbbbbbbi(bbbbbbbbbbbbbbi

BBBBMMMBMMMMBBBBBMMI200 «- JOO <00 500 600

45 + 49

imnnni. ::::::::::::•» :«S""SSH«*K;

i»:s::::::sy

^•nflavaSSSBBBaBi100 JOO 400 S00 600 700

35 + 45

IBBBBBBBBBBBBBBBIIBI BBBBIIBBBBBI— ——U BB.IBBBI__

IBBBBBBBBBBBBB1tlllllllllllltlilHUH«BHflBWfBflBflBfl|:tjBHBBBBI•BBB IBBBB I3BBB 7MB" llllllllNmil»»IBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBflBBBBBBBBIBBBBBBBBBBBBBBBBBBBBBBBIHBI

200 300 400 S00 600 700

45 + 58

;MBB» * BBBBBBBBBI BBBBIIBBBt IBBan **** HI BBBBIIBBBB IUIIIIHI l|[ jlllll

BIBflB BBBBBI

^BBBBBBBBBBBBBBBBBBBBBBBIBBBBBBBBBBBBBBBBBBBBBBBBIBBBBBBBBBBBBBBBBBBBBBBBBI

200 300 400 S00 600 700

22 + 58

——IT TBWBB1BBBBBBBBBBBBBBBI

BBBBBBBBBBBBBBBJBBBBBBBI

BBBBBBBBBBBBBBBBBBBBBBBB

BBBBBBBBBBBBBBBBBBBBBBBB200 300 400 500 600 700

15 + 45

BBBBBBBBBIflBflBIIH IBBmlmilIUU'

iGii__ILJBBBI

yBBBBBBBBBBBBBBBBBBBBBBBI

MBBJBMMBBMMBMMBBBMBMMBJ

—

200 300 400 S00 600 700

23A + 61

The curves show the transmitiance of certain pairs offilters. The combined transmittance value for anygiven wavelength can be calculated by multiplyingtogether the separate percentage values and dividingby 100.

58

The curves show the transmittance of certain pairs of

filters. The combined transmittance value for any

given wavelength can be calculated by multiplying

together the separate percentage values and dividing

by 100.

59

25 : 58 : 47

a&. m aitllllllMlllilia^ JHIBBE»i iana - !iMmmmmmi29 : 61 : 49

60

The diagrams show, superimposed, the curves ofcertain 'Wratten' filters. They are given in this formto show relative absorption characteristics and tofacilitate comparison of density and transmittancevalues.

KSSSSSSSii

1%

I10%

NDI.O

AMRLSia!IJIhbw<«JW«FW r

MMBBSB1

«fflnaaHBHi

ji!innii!!IMlI!

0-1%

I8A

.1

!

M ii*m

01%

700 800 900

I8B

10%

100%

INFRA-RED TRANSMISSION

NDI.O I8A I8B

700 9.52 1.20 33.1

10 10.0 3.10 45.7

20 13.5 5.63 54.9

30 16.6 8.51 58.9

40 18.6 10.7 60.3

50 19.9 10.7 58.0

60 20.9 7.95 57.6

70 21.8 5.50 54.9

80 22.4 3.72 53.8

90 22.9 2.57 52.5

800 23.3 1.82 50.1

10 23.8 1.26 49.0

20 24.3 0.91 47.9

30 24.7 0.65 46.7

40 25.1 0.47 45.7

50 25.5 0.32 45.7

60 25.9 0.22 43.7

70 26.3 0.15 41.8

80 26.6 0.10 36.3

90 26.9 — 31.6

900 27.2 — 28.8

10 27.5 — 25.7

20 27.8 — 23.5

30 28.2 — 21.9

40 28.5 — 20.4

50 28.8 — 19.1

The tables and curves show the infra-red

transmission of certain special filters

between wavelengths 700 and 950 m\i,

61

INFRA-RED TRANSMISSION

45 47 74

1.0 — — 700

8.30 0.10 — 10

29.5 0.42 — 20

56.4 1.32 — 30

70.9 3.98 — 40

77.6 10.0 0.69 50

81.4 20.9 4.26 60

84.0 37.2 15.8 70

86.1 53.7 30.2 80

87.8 66.0 44.6 90

89.2 74.2 56.4 800

90.1 79.5 64.6 10

90.8 83.2 70.8 20

91.0 85.1 76.0 30

91.0 86.3 80.5 40

91.0 87.2 83.2 50

91.0 88.0 85.0 60

91.0 88.6 86.0 70

91.0 89.1 86.8 80

91.0 89.7 87.2 90

91.0 90.2 87.4 900

91.0 90.5 87.5 10

91.0 90.8 87.7 20

91.0 90.9 87.9 30

91.0 91.0 88.1 40

91.0 91.0 88.1 50

The tables and curves show the infra-red

transmission of certain special filters

between wavelengths 700 and 950 mu..

62

E700 800 900

45

lEl

ii

i«800 900

47

Mlml

H"t-LriiniiH|&iil,IMIk

700 800

74

1%

1%

10%

IOCX

01%

10%

100%

01%

MM I

I E Si

I P "'B-la | 111i ci~S-— -

01%

i%

Owo

zz2-10%

100%

700 800 900

87

10%

100%

2

j-

"

a

1

0-1%

10%

100%700

88A

900

INFRA-RED TRANSMISSION

87 88A

700 — — —10 — — —20 — — —30 — 7.40 —40 0.10 32.8 —50 2.19 56.3 —60 7.95 69.2 —70 17.4 74.2 —80 31.6 77.6 —90 43.7 79.7 —

800 53.8 81.4 —10 61.7 82.6 —20 69.2 83.7 —30 74.1 84.7 —40 77.7 85.5 —50 81.4 86.1 —60 84.0 86.6 —70 85.4 87.2 —80 86.8 87.5 —90 87.8 87.8 —

900 88.4 88.0 —10 88.8 88.2 —20 89.1 88.4 —30 89.1 88.6 —40 89.1 88.8 —50 89.1 89.0 —

The tables and curves show the infra-red

transmission of certain special filters

between wavelengths 700 and 950 mil.

63

RED CYAN

CC-05R CC-IOR CC-20R

400 81.0 73.0 61.5

10 81.0 72.4 60.0

20 81.0 72.0 58.6

30 81.1 71.6 57.7

40 81.2 71.5 57.2

50 81.4 71.6 57.2

60 81.7 72.4 58.5

70 82.3 73.7 60.6

80 82.8 74.9 62.0

90 83.2 75.8 63.5

500 83.3 76.6 64.6

10 83.0 76.1 64.0

20 82.4 74.9 61.5

30 81.6 73.5 59.4

40 81.2 72.5 57.8

50 81.1 72.4 57.1

60 81.4 72.8 58.4

70 82.5 74.5 60.6

80 83.9 77.3 65.0

90 85.7 80.7 61.0

600 87.6 84.0 77.0

10 89.0 86.5 82.0

20 90.0 88.9 86.2

30 90.6 89.9 88.1

40 91.1 90.5 89.8

50 91.2 90.8 90.5

60 91.3 91.1 90.8

70 91.4 91.3 91.0

80 91.6 91.5 91.2

90 91.7 91.7 91.4

700 91.9 91.9 91.5

*A .4562

.4044

.4649

.4021

.4813

.3956

yA .846 .787 .681

*c .3170

.3171

.3246

.3194

.3385

.3199

yc .837 .770 .653

CC-05C CC-IOC CC-20C

400 87.3 86.0 83.9

10 88.2 87.5 85.2

20 88.7 88.1 86.5

30 89.0 88.6 87.5

40 89.3 89.0 87.7

50 89.5 89.1 87.8

60 89.6 89.1 87.7

70 89.7 89.0 87.5

80 89.7 89.0 87.2

90 89.7 89.0 87.0

500 89.6 89.0 86.5

10 89.6 88.7 86.0

20 89.5 88.5 85.2

30 89.4 88.0 84.3

40 89.2 87.5 83.4

50 88.9 87.0 82.3

60 88.5 86.1 80.5

70 88.0 85.0 78.5

80 87.5 83.8 76.1

90 87.0 82.5 73.9

600 86.4 81.0 71.2

10 85.5 79.5 78.5

20 84.5 77.9 75.5

30 83.8 76.3 72.7

40 83.3 75.1 60.8

50 82.8 74.4 59.5

60 82.5 74.0 58.5

70 82.4 73.6 57.9

80 82.0 73.0 57.5

90 82.0 72.8 57.4

700 82.5 74.0 58.5

*A

3»A

.4422

.4090

.4350

.4102

.4211

.4117

^A .874 .838 .764

.3053

.3156

.2997

.3135

.2882

.3084

Yc .880 .851 .789

64

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CC-05CCC-IOCCC-20C

V»»VtlSNCTH(mj.)

65

GREEN MAGENTA

CC-05G CC-IOG CC-20G

400 80.0 73.1 58.8

10 80.7 72.9 57.8

20 81.0 72.8 57.3

30 81.4 72.7 57.0

40 81.6 73.0 57.3

50 82.1 73.9 53.4

60 83.0 75.5 61.4

70 84.4 78.0 65.4

80 85.6 80.4 70.0

90 86.8 83.0 75.2

500 87.9 85.9 80.3

10 88.7 87.5 83.8

20 89.0 88.1 84.9

30 89.0 88.0 84.6

40 89.0 87.6 83.7

50 88.6 87.1 82.4

60 88.1 86.3 80.9

70 87.5 85.3 79.0

80 87.0 84.1 77.0

90 86.4 82.8 74.5

600 85.7 81.5 72.0

10 85.0 80.0 69.5

20 84.0 78.5 66.5

30 83.0 76.9 63.8

40 82.2 75.6 61.5

50 81.9 74.9 60.1

60 31.5 74.4 59.4

70 81.4 74.0 58.8

80 81.1 73.5 58.1

90 81.1 73.2 57.6

700 81.5 73.5 58.0

XA

3»*

.4451

.4131

.4434

.4193

.4386

.4319

^A .868 .837 .763

.3105

.3245

.3117

.3340

.3131

.3533

yc .872 .845 .778

CC-05M CC-IOM CC-20M

400 87.6 86.6 85.6

10 88.2 87.7 86.6

20 88.6 88.0 87.0

30 88.7 88.0 86.9

40 88.7 87.9 86.0

50 38.6 87.5 84.9

60 88.4 86.5 83.1

70 87.8 85.2 80.8

80 87.0 83.6 77.9

90 86.0 81.8 74.4

500 85.0 79.7 70.5

10 83.8 77.5 66.7

20 82.7 75.3 63.4

30 81.8 73.7 60.5

40 81.3 72.5 53.6

50 81.2 72.2 58.0

60 81.5 72.8 58.3

70 82.5 74.6 60.5

80 84.0 77.3 64.9

90 85.8 80.8 70.6

600 88.0 84.5 77.1

10 89.3 87.0 82.2

20 90.2 88.9 86.1

30 90.6 90.0 88.7

40 90.8 90.5 90.0

50 91.0 90.7 90.5

60 91.1 91.0 90.8

70 91.2 91.2 91.0

80 91.3 91.3 91.2

90 91.4 91.4 91.4

700 91.5 91.5 91.5

*A

yA

.4524

.4004

.4563

.3929

.4628

.3787

y. .849 .791 .690

.3114

.3082

.3114

.2986

.3104

.2808

^c .842 .779 .671

66

10

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CC-05MCC-IOMCC-20M

WAVELENGTH (mp)

67

BLUE YELLOW

CC-05B CC-IOB CC-20B

400 87.0 85.5 82.2

10 87.5 86.4 84.0

20 87.7 87.2 85.0

30 88.0 87.5 85.3

40 88.1 87.5 85.0

50 88.1 87.2 83.9

60 87.9 86.4 82.5

70 87.5 85.3 80.3

80 87.0 84.0 77.8

90 86.2 82.4 74.2

500 85.2 80.5 71.2

10 84.4 78.6 67.7

20 83.5 77.0 64.0

30 82.6 75.2 61.5

40 82.1 73.9 59.5

50 81.5 73.0 58.0

60 81.4 72.7 57.5

70 81.4 73.0 57.9

80 81.9 73.9 59.3

90 82.7 75.1 61.6

600 83.4 76.3 63.5

10 83.6 76.7 64.5

20 83.5 76.5 64.3

30 83.2 76.6 63.1

40 82.8 74.5 61.6

50 82.5 74.0 60.6

60 82.5 73.8 60.1

70 82.3 73.3 59.6

80 82.0 72.8 58.6

90 81.9 72.5 58.1

700 82.2 73.0 58.5

*A .4449

.4053

.4405

.3984

.4328

.3871

n .911 .750 .615

yc

.3057

.3087

.2994

.2987

.2881

.2789

Yc .828 .755 .623

CC-OSY CC-IOY CC-20Y

400 81.0 74.5 61.3

10 80.6 73.2 59.0

20 80.4 72.6 57.8

30 80.4 72.5 57.5

40 80.6 72.8 57.8

50 81.2 74.0 59.5

60 82.5 76.0 63.0

70 83.9 78.5 67.5

80 85.3 81.2 72.3

90 87.0 84.4 78.0

500 88.4 87.2 84.0

10 89.5 89.0 88.0

20 90.0 90.0 89.6

30 90.4 90.4 90.0

40 90.7 90.7 90.6

50 90.9 90.9 90.8

60 91.0 91.0 90.9

70 91.3 91.3 91.0

80 91.4 91.4 91.1

90 91.4 91.4 91.2

600 91.4 91.4 91.3

10 91.4 91.4 91.3

20 91.4 91.4 91.3

30 91.5 91.5 91.4

40 91.5 91.5 91.4

50 91.5 91.5 91.4

60 91.5 91.5 91.4

70 91.5 91.5 91.4

80 91.5 91.5 91.4

90 91.5 91.5 91.4

700 91.5 91.5 91.4

*A

-VA

.4531

.4125

.4567

.4166

.4643

.4249

^A .909 .907 .903

yc

.3181

.3283

.3239

.3382

.3369

.3597

Yc .904 .901 .891

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70

COLOUR SPECIFICATIONFor consistency, colours need to be defined more accurately than simply

by analogy with familiar objects. To the human observer, colours can

be considered as having three attributes (as solid objects have three

dimensions) and they can be loosely defined as follows

—

Hue (the kind of colour) e.g. red, yellow, bluish-green, etc. ; saturation

(the purity of colour) that is, the extent to which the hue appears to be

diluted with white or grey, and lightness, the degree to which the colour

appears to reflect or transmit the incident light.

These psychological characteristics of colour can be illustrated by the

following examples. A pale pink is predominantly red in hue, of low

saturation, but of fairly high lightness. If the saturation had been high

and the lightness low, the colour would have been a rich deep red.

There is often confusion when a colour is merely described as "bright".

A saturated red, for example, may be described as a "bright red," when it

is really just a strong or intense red that may not, in fact, be as light as a

pale pink which reflects more light. There is also a possibility of mis-

taking low lightness for saturation. For instance, the rich blue sky in a

colour photograph may appear saturated, but when compared with a

tri-colour blue filter, it will clearly be of much lower saturation and

lightness.

The CLE. System

The physical characteristics of light and colours can be measured by

instruments and expressed in terms of the amount of light present at each

wavelength of the spectrum (as in a spectrophotometric curve), but, to be

of full practical value, colour specification data must also take into account

the psychological reactions of the human observer. The recommenda-

tions of the International Commission of Illumination have been widely

accepted as the basis of a standard psycho-physical system of colour

specification, and are referred to as the CLE. system. The initials CLE.stand for the official title "Commission Internationale de l'Eclairage,"

but in America the initials I.C.I, are sometimes used.

By mixing three lights (not pigments or inks) any colour (even spectral

colours) can be matched.* Although these lights, referred to as primaries,

could be of any three colours they are preferably red, green and blue and

preferably of high saturation.

The CLE. system specifies colours in terms of the amounts X, Y, and

Z of each ofthree primaries! Px Py and Pz, which would have to be mixed

to match the sample.

* Sometimes the amounts of the lights needed will be negative, which means that

they have to be added to the sample colour instead of to the comparison mixture.

+ The CLE. primaries Px Py and Pz are, themselves, denned in terms of the

amounts of a standard set of red, green and blue spectral primaries needed to

produce them, and some of these amounts are negauve.

71

By plotting the amounts of the CLE. primaries required to match eachwavelength of the spectrum, in the opinion of a large number of observers,

and taking averages, data for the "standard observer" are obtained.

With this as the psychological basis, and a spectrophotometric curvesupplying the physical data, the colour specification of a sample can becomputed and stated with respect to a specified light source without anypractical colour matching having to be done*.

But hue, saturation, and lightness are sensations in the human brain,

and cannot be measured by means of physical trichromatic matching.Quantities analogous to these sensations can, however, be quite simplyobtained from colour matching data, and in the CLE. system they are

called dominant wavelength, purity and luminance factor respectively andare measured from the chromaticity diagram prepared as follows. Thechromaticity diagram, a "colour map" of all possible dominant wave-lengths and purities, can be plotted graphically, the x and y co-ordinates

being derived fromX, Y and Z values for each colour in the followingmanner.

Xx =

X + Y + Zy = X+Y + Z

The positions of the colours having the highest possible purity (the

spectral colours) lie on a horseshoe-shaped line, along which the

wavelengths are marked. This boundary line is called the spectral locus.

The straight line joining the bottom ends of the horseshoe represents the

magentas and purples at maximum purity and, not being colours occurringin the spectrum, their wavelengths are normally quoted as for their "green"complements with the inferior index "C," e.g. 566c . The positions in

the diagrams representing various "white" illuminants, such as sunlight,

tungsten fight, fluorescent light, etc., are a little below the centre. On a

straight line drawn out from any such point will lie the positions of all

colours ofthe same dominant wavelength relative to the particular illuminant

being used, and this wavelength is indicated at the point on the spectral

locus where the straight line cuts it.

Colours lying on the same line are low in purity when near the illuminant

point, and increase in purity as they approach the spectral locus. Whenthe distance from the illuminant point to the sample point is divided bythe total distance from the illuminant point to the spectral locus, the valueobtained is called the excitation purity of the colour.

The value of dominant wavelength and excitation purity together locate

the position of a colour sample within the spectral locus ofthe chromaticity

diagram, but a more convenient definition of the point is given by quotingits co-ordinates x, y on which the diagram is based.

* See "The Measurement of Colour" by W, D. Wright, Adam Hilger, London, 1944; "TheHandbook of Colorimetry" by A. C. Hardy, Massachusetts Institute of Technology, 1936, or"The CLE. International Colour System Explained" by G. I. Chamberlin, Tintometer,Salisbury, 1951.

71

As the chromaticity diagram has only two dimensions it can only

demonstrate dominant wavelength and purity. It is therefore obvious

that what has been called the "illuminant" point is in reality the "neutral"

point, being equally applicable to any density of neutral grey as seen by

the specified light-source.

The third variable used in the CLE. system to denote lightness is the

luminance factor or Y value*, which is the ratio of the visual response to

the illuminant after reflection from the surface, or passage through the

filter, to that from the illuminant beam direct, i.e., the reflection factor or

the transmission factor.

The CLE. specification of a colour therefore states the x and y co-

ordinates, together with the Y value. These three values are quoted in

the filter data tables in this book. It is important to remember that the

colour specifications only hold for the illuminant stated. With other fight

sources new values of x, y and Y have to be evaluated from the official

CLE. tables representing the standard observert.

The relative positions of colours within the CLE. chromaticity diagram,

unfortunately, do not give an accurate impression of the actual differences

in colour. The "scale" of the visual effect is not constant in all directions

Continued on page 78

* The primary ~Px has been chosen to consist of light of one colour added to the

mixture beam, and light of another colour added to the test-colour beam ; the

amounts added to each are of equal luminance. Similarly, the primary Pz adds

equal amounts of light (of different colours) to the two beams. Thus all the

luminance of the test colour has to be balanced by the primary Py and hence the

lightness of a colour is independent of the values X and Z. For convenience,

instead of the actual Y reading being quoted, the Y value is taken as the ratio

(usually as a percentage) of the amount ofthe primary Py needed in matching the

colour, to the amount of the primary Py needed in matching the illuminant.

f The basic tables are in the form of tabulated values of the amounts of the

primaries Pat, Py and Pz needed to match unit energy ofeach wavelength of the

spectrum. These are denoted by the symbols x\, yx and zx respectively, and

Y =

y =

s

2 Eh.Tx.y\Ax

8

where 8 = 1 Ex.Tx.xx.bx + 2 Ex.Tx.yx^x + X Ex.Tx.zxAy,

Ex is the energy of the source at wavelength x and Tx is the transmission factor

of a filter or the reflection factor of a surface, at wavelength x. Owing to the fact

that all the luminance of a test colour has to_be balanced by the luminance of the

amount of the primary P y in a match, the yx curve is the same as the luminosity

curve Vx of the eye.

73

CHROMATICITY DIAGRAM

To Standard lliuminant 'A'

(Artificial light)

The chromaticity diagram on this page shows the positions of'Wratten' filters relative to the point representing the Standardlliuminant "A" specified by the "Commission" Internationale

de I'Eclairage 1931. The Standard lliuminant "A" has acolour temperature of 2854°K, equivalent to high-wattagetungsten lighting. The co-ordinates xa and y\ for each filter

are given in the data tables on pages 36 to 56.

The rectangular outlined portion in the middle of thediagram shows the area covered by the enlarged section onpage 76.

74

CHROMATICITY DIAGRAM

To Standard lliuminant 'C(Daylight)

The chromaticity diagram on this page shows the positions of

'Wratten' filters relative to the point representing the Standard

lliuminant "C" as specified by the "Commission" Inter-

nationale de I'Eclairage 1931. The Standard lliuminant "C"

is approximately equivalent to a mixture of sunlight and

skylight of a colour temperature of 6500 'K. The co-ordinates

A C and yc for each filter are given in the data tables on

pages 36 to 56.

The rectangular outlined portion in the middleof thediagram

shows the area covered by the enlarged section on page 77.

75

CHROMATICITY DIAGRAMTo Standard llluminant 'A'

(enlarged section for filters of small colour differences)

•S2

S

•48580 m/X

46

44IUUHIHANT 'A'

• KG // . 2CY

•42-IOC /

y

/ -10V

-OC.or»G/.05Y8.B . g|C -8IEF

,0C 05C- o/-8l 8*, A%86C

86A-

•4

79C. B2.-«B -05R .

«A..|0B

•««

«C *» MOM -

,0R

• 206

38

•?8A

20M /

•36

•34

•so*

32

3

34 36 38 •42 •44 46 :a •52

76

The diagram on this page is an enlargement of the portionindicated by the small rectangle in the standard CLE.chromaticity diagram on page 74.

It shows the positions relative to Standard llluminant "A"of certain filters which, due to small differences in hue andsaturation, are grouped closely together. Filters of this

nature, such as 'Kodak' Colour Compensating Filters and'Wratten' Light Balancing filters, are frequently used in

colour photography and for visual colour work. The co-ordinates of the CC filters are given on pages 64, 66 and 68.

CHROMATICITY DIAGRAMTo Standard llluminant 'C

(enlarged section for filters of small colour differences)

•38

•34

•34

-32

28

•26

24

•22

• 8IEF

I0R- 20R

22 -24 26 28 •32 •34 •36 •38

The diagram on this page is an enlargement of the portion

indicated by the small rectangle in the standard CLE.chromaticity diagram on page 75.

It shows the positions relative to the Standard llluminant

"C" of certain filters which, due to small differences in hue

and saturation, are grouped closely together. Filters of this

nature, such as 'Kodak' Colour Compensating Filters and

'Wratten' Light Balancing Filters, are frequently used in

colour photography and for visual colour work. The co-

ordinates of the CC filters are given on pages 64, 66 and 68.

77

and positions, as can be seen from the following diagram in which steps

of equal colour difference are represented by the lengths of the lines.

By comparing the diagram on page 74 with the one below, it will be

appreciated that the difference between 'Wratten' filters No. 35 and 36 is

approximately the same as between No. 59 and 61, though the first pah-

would seem to be very similar and the second pair well separated.

. 520 mfi

— + 11 \,/J \- 620 m p.

-\ \630m/4

48Smp.

640m/i

mml\ z\

470m/i\ '//

\380 mn

•3 -4

XS -6 -7 8

Diagram reproduced by kind permission of Professor W. D. Wright and the Physical Society.

78

COLOUR TEMPERATURE CORRECTIONThe colour quality of an illuminant may be expressed in terms of "colour

temperature"—a measure which defines the colour of a light-source by

reference to the visual appearance of the light radiated by a black body

heated to incandescence. This measurement is expressed in degrees

Kelvin (°K.).

Each colour temperature can have assigned to it a " mired " value

(micro-reciprocal degree Kelvin). 'Wratten' Photometric filters and

Light-Balancing Filters have the power to shift the colour temperature,

and hence the mired value, of any one light-source by a definite amount.

Each filter can therefore be given a "mired shift value," represented by

the expression (—-— ) 106

when T, represents the colour temperature of the original light source, and

T2the colour temperature of the light through the filter. This value

will be either positive or negative according to the colour of the filter.

Yellowish or amber filters, which lower the colour temperature and there-

fore increase the mired value, will have a positive value; those in the bluish

series, which raise the colour temperature and therefore reduce the mired

value, will have a negative value.

The chart on the next page shows the comparison between various

colour temperatures and their associated mired values. To find the mired

shift value of the filter required it is only necessary to determine the

difference in mired values between the colour temperature of the light-

source in use, and that of the light required. Taking into account the

positive (towards blue) or negative (towards red) bias, the necessary

correction filter can be found by selecting one that has the nearest mired

shift value.

Filters may be combined, the desired combination being calculated by

adding the mired shift values of the filters, with due regard to the sign.

If more than one filter is used, it should be remembered that the reflection

loss due to the multiple surfaces may become considerable. This,

however, can be partly eliminated by cementing the filters together in

pairs.

Mired Shift Values

Towards blue 82 -1<H Towards yellow 81 H82A —21 81A hl8J

82B —32J 81B -f-27

82C -44?. 81C 35

78A -Ill 81EF :-53

78C -24 86A

86C

85

85B

-111

:-24

-127

-146

79

1.500 2.000 3,000 4,000 S^OOO 6.000 7,000 8,000 9.000 10,000

1.503 2,000 3.000 1,000 i.OOO 6.000 7.000 8,000 9,000 10.000

COLOUR TEMPERATURE (°KELVIN)

TECHNICAL DEFINITIONSThe Spectrum

The name "spectrum" is applied to the band of colours formed whena narrow beam of white light is split into its constituent colours by meansof a prism or diffraction grating. This is obtained by the differential

dispersion of light of different wavelengths, which gives rise to an over-

lapping series of six distinct colour bands ; red at the longer wavelength

end of the scale, and passing through orange, yellow, green and blue to

violet at the short-wavelength end of the scale.

WAVELENGTH in millimicrons

10-* IO-< 10-' 1 I0 2 10* 10* io» io'» io 12 ioH io'*

COSMIC GAMMA X-RAYS ULTRA-RAYS RAYS VIOLET

RAYS

1 1

INFRA

-REDRAYS

1

HERTZIAN RADAR RADIOWAVES AND WAVES

TELEVISIONWAVES

1 1

LONGELECTRICAL

OSCILLATIONS

1 Anjilrom Unit 1 Millimicron 1 Millimtttr 1 Meter 1 Kilometer

f VISIBLE SPECTRUM 1I00mj» 700m,i

80

The visual spectrum extends from approximately 400 m<x at the blue endto 750 m;x at the red end; beyond these two extremes exists a series of

invisible radiations extending through infra-red to heat waves, short andlong wave wireless transmissions, and through ultra-violet to X-raygamma-ray and cosmic radiations.

Whilst scientists and research workers, using special materials, make use

of the photographic process to record phenomena occuring far beyond the

visible spectrum, the average practical photographer need only be con-

cerned with the effect obtained from visible light rays, and to a lesser

extent those from the nearer infra-red and ultra-violet regions.

Wavelength

Light can be defined as visible electro-magnetic radiation, the charac-

teristics of which may be represented by a

sine-wave form. The distance betweencorresponding points in a full cycle of the

wave is termed the wavelength (x) of the

radiation. Wavelength provides a measure

of the colour characteristic of light.

The standard unit of wavelength measurement is the "micron" (u)

which is equal to 10-3

millimetre. This, however, is an inconveniently

large unit by which to measure the wavelength of light. Two other

smaller units of measurement are therefore used, the "millimicron" (mu),

equal to 10-8 millimetre and, less usually, the " Angstrom Unit " (A)

which is equal to IO-7 millimetre.

The millimicron (ma) has been adopted as being the most convenient

way of expressing the measurement of wavelength throughout this book.

81

Ultra-violet Radiations

Ultra-violet radiations extend beyond the visible region of the spectrumand are of wavelength shorter than the blue-violet, starting at approxi-

mately 400 m;o.. This radiation is usually considered undesirable by mostphotographers as it is recorded in the form of aerial haze, particularly at

high altitudes, and an excess blue colour cast when using colour films.

Its effect on sensitized emulsions can be suppressed by the use of niters

such as 'Wratten' No. 1A or 2B. Radiations of wavelengths below330 mjx can usually be disregarded, as the lens glasses (except those

specially constructed of quartz) normally absorb strongly below this figure.

Certain materials are known to fluoresce (i.e. emit visible light, often

coloured) under ultra-violet light, and photographs taken of an object

illuminated by the ultra-violet fight passing through a 'Wratten' No. 18Afilter are often used in forensic photography. The sensitive material mustbe protected from the direct ultra-violet radiation by using a 'Wratten'

No. 2B filter over the lens of the camera.

Infra-red Radiations

Infra-red radiations extend beyond the visible region of the spectrumbut are of wavelength longer than the red, starting at approximately680 m\i. Infra-red radiations present in daylight are very variable in

amount; this amount is not directly related in any way to the visual

intensity of the light.

Normal photographic emulsions are insensitive to infra-red, but specially

sensitized plates can be used to obtain photographs in total darkness using

a 'Wratten' No. 87 or 88A filter.

Transmission

The transmission of a given filter, defined as being the ratio of the light

transmitted by a filter to the light incident upon it, is usually expressed as

a percentage. This will vary according to the wavelength of the incident

light. By examining the transmission of a filter in a spectro-photometer

at varying wavelengths and plotting these values against the wavelength, a

curve can be obtained representing the transmission characteristics of the

filter. The curves shown on pages 36 to 70 were obtained in this mannerand form a useful and ready form of reference.

Absorption

The absorption of a filter is very often required to be known in order

to calculate the effect of the filter on the tone rendering given by a photo-graphic emulsion. The absorption factor is also usually expressed as a

percentage value and is the complement of the transmission figure.

Density

Density, in its photographic sense, can be defined as the term applied

to the degree of opacity or absorption of an exposed and processed photo-graphic emulsion and can be determined from the equation

:

Density = log 10 Transmission(where the transmission is expressed in fractional form).

82

A density of 1.0 will therefore correspond to a transmission of 1/10 or

10 per cent.; a density of 2.0 will correspond to a transmission of 1/100 or

1 per cent. ; and a density of 3.0 to a transmission of 1 /1000 or 0.1 per cent.

(see table on pages 84 and 85).

The term is applied usually, but not exclusively, to photographic silver

deposits : it can also be applied to the colour absorption of a filter. In this

connection it is frequently used in preference to transmission values

because of its mathematical simplicity, in so far that the combined density

of two or more filters is equal to the sum of their individual densities.

The transmission and density graphs on pages 36 to 70 have been

measured to a maximum density of 3, corresponding to a transmission

factor of 0.1 per cent. This figure is the maximum density ever likely to

be required in normal photographic work.

Colour Temperature

In order to define the term "colour temperature" it is necessary to

make use of the concept of "black-body radiation."

A "black-body" is defined as a body that absorbs all the radiation

falling on it. It has the property of radiating more energy at any wave-

length than any other body at the same temperature, so that black-body

radiation represents a limit which can never be exceeded by the lamp.

The quality of the radiation from such a black-body depends solely on

the temperature, so that all black-bodies at the same temperature have

the same colour and distribution of energy throughout the spectrum.

The spectral quality of the radiation from an incandescent source may

be different from that from a black-body, but if the temperature of the

black-body can be varied till the two sources have the same visual colour,

then the temperature of the black-body is the colour temperature of the

incandescent source.

Colour temperature is measured on the absolute scale in "degrees

Kelvin" (

CK), that is, the Centigrade temperature plus 273°

; in the case

of a tungsten lamp it happens that the colour temperature is about 50°K.

higher than the absolute temperature of the filament.

The CLE. System

For a full explanation of the CLE. system of colour specification see

pages 71 to 78.

83

DENSITY/PER CENT. TRANSMISSION TABLE

Per Cent.

Transmission .1 .2 .3 .4 .5 .6 .7 .8 .9

3.00 2.70 2.52 2.40 2.30 2.22 2.15 2.10 2.051 2.00 1.96 1.92 1.89 1.85 1.82 1.80 1.77 1.74 1.722 1.70 1.68 1.66 1.64 1.62 1.60 1.59 1.57 1.55 1.543 1.52 1.51 1.50 1.48 1.47 1.46 1.44 1.43 1.42 1.414 1.40 1.39 1.38 1.37 1.36 1.35 1.34 1.33 1.32 1.31

5 1.30 1.29 1.28 1.28 1.27

1.19

1.26

1.19

1.25 1.24 1.24 1.23

6 1.22 1.21 1.21 1.20 1.18 1.17 1.17 1.167 1.15 1.15 1.14 1.14 1.13 1.13 1.12 1.11 1.11 1,108 1.10 1.09 1.09 1.08 1.08 1.07 1.07 1.06 1.06 1.059 1.05 1.04 1.04 1.03 1.03 1.02 1.02 1.01 1.01 1.0010 1.00 1.00 .99 .99 .98 .98 .97 .97 .97 .96

II .96 .95 .95 .95 .94 .94 .93 .93 .93 .9212 .92 .92 .91 .91 .91 .90 .90 .90 .89 .8913 .89 .88 .88 .88 .87 .87 .87 .86 .86 .8614 .85 .85 .85 .84 .84 .34 .84 .83 .83 .8315 .82 .82 .82 .82 .81 .81 .81 .80 .80 .80

16

17

.80

.77

.79

.77

.79

.76

.79

.76

.78

.76

.78

.76

.78

.75

.78

.75

.77

.75

.77

.7518 .74 .74 .74 .74 .73 .73 .73 .73 .73 .7219 .72 .72 .72 .71 .71 .71 .71 .71 .70 .7020 .70 JO .69 .69 .69 .69 .69 .68 .68 .68

21 .68 .68 .67 .67 .67 .67 .67 .66 .66 .6622 .66 .66 .65 .65 .65 .65 .65 .64 .64 .6423 .64 .64 .63 .63 .63 .63 .63 .63 .62 .6224 .62 .62 .62 .61 .61 .61 .61 .61 .60 .6025 .60 .60 .60 .60 .59 .59 .59 .59 .59 .59

26 .58 .58 .58 .58 .58 .58 .57 .57 .57 .5727 .57 .57 .57 .57 .56 .56 .56 .56 .56 .5628 .55 .55 .55 .55 .55 .54 .54 .54 .54 .5429 .54 .54 .53 .53 .53 .53 .53 .53 .53 .5230 .52 .52 .52 .52 .52 .52 .51 .51 .51 .51

31 .51 .51 .51 .50 .50 .50 .50 .50 .50 .5032 .49 .49 .49 .49 .49 .49 .49 .49 .48 .4833 .48 .48 .48 .48 .48 .47 .47 .47 .47 .4734 .47 .47 .47 .46 .46 .46 .46 .46 .46 .4635 .46 .45 .45 .45 .45 .45 .45 .45 .45 .44

36 .44 .44 .44 .44 .44 .44 .44 .44 .43 .4337 .43 .43 .43 .43 .43 .43 .42 .42 .42 .4238 .42 .42 .42 .42 .42 .41 .41 .41 .41 .4139 .41 .41 .41 .41 .40 .40 .40 .40 .40 .4040 .40 .40 .40 .40 .39 .39 .39 .39 .39 .39

41 .39 .39 .39 .38 .38 .38 .38 .38 .38 .3842 .38 .38 .38 .37 .37 .37 .37 .37 .37 .3743 .37 .37 .37 .36 .36 .36 .36 .36 .36 .3644 .36 .36 .35 .35 .35 .35 .35 .35 .35 .3545 .35 .35 .34 .34 .34 .34 .34 .34 .34 .34

46 .34 .34 .33 .33 .33 .33 .33 .33 .33 .3347 .33 .33 .33 .32 .32 .32 .32 .32 .32 .3248 .32 .32 .32 .32 .32 .31 .31 .31 .31 .3149 .31 .31 .31 .31 .31 .31 .30 .30 .30 .3050 .30 .30 .30 .30 .30 .30 .29 .29 .29 .29

Locate the density reading in the table. The whole number at the extreme left plus the decimal numberat the top of the column In which the reading is located is the per cent, transmission of the density. Forexample, the percent, transmission of a density of 1.29 is 5.1 percent. For a density that appears more

84

DENSITY/PER CENT. TRANSMISSION TABLE

Per Cent.

Transmission

51

.1 .2 .3 .4 .5 .6 .7 .8 .9

.29 .29 .29 .29 .29 .29 .29 .29 .29 .28

52 .28 .28 .28 .28 .28 .28 .28 .28 .28 .28

53 .28 .28 .27 .27 .27 .27 .27 .27 .27 .27

54 .27 .27 .27 .27 .26 .26 .26 .26 .26 .26

55 .26 .26 .26 .26 .26 .25 .25 .25 .25 .25

56 .25 .25 .25 .25 .25 .25 .25 .25 .25 .24

57 .24 .24 .24 .24 .24 .24 .24 .24 .24 .24

58 .24 .24 .24 .23 .23 .23 .23 .23 .23 .23

59 .23 .23 .23 .23 .23 .23 .22 .22 .22 .22

60 .22 .22 .22 .22 .22 .22 .22 .22 .22 .22

61 .21 .21 .21 .21 .21 .21 .21 .21 .21 .21

62 .21 .21 .21 .21 .20 .20 .20 .20 .20 .20

63 .20 .20 .20 .20 .20 .20 .20 .20 .20 .19

64 .19 .19 .19 .19 .19 .19 .19 .19 .19 .19

65 .19 .19 .19 .19 .18 .18 .18 .18 .18 .18

66 .18 .18 .18 .18 .18 .18 .18 .18 .17 .17

67 .17 .17 .17 .17 .17 .17 .17 .17 .17 .17

68 .17 .17 .17 .17 .16 .16 .16 .16 .16 .16

69 .16 .16 .16 .16 .16 .16 .16 .16 .16 .16

70 .15 .15 .15 .15 .15 .15 .15 .15 .15 .15

71 .15 .15 .15 .15 .15 .15 .14 .14 .14 .14

72 .14 .14 .14 .14 .14 .14 .14 .14 .14 .14

73 .14 .14 .14 .13 .13 .13 .13 .13 .13 .13

74 .13 .13 .13 .13 .13 .13 .13 .13 .13 .13

75 .12 .12 .12 .12 .12 .12 .12 .12 .12 .12

76 .12 .12 .12 .12 .12 .12 .12 .12 .11 .11

77 .11 .11 .11 .11 .11 .11 .11 .11 .11 .11

78 .11 .11 .11 .11 .11 .10 .10 .10 .10 .10

79 .10 .10 .10 .10- .10 .10 .10 .10 .10 .10

80 .10 .10 .10 .10 .09 .09 .09 .09 .09 .09

81 .09 .09 .09 .09 .09 .09 .09 .09 .09 .09

82 .09 .09 .08 .08 .08 .08 .08 .08 .08 .08

83 .08 .08 .08 .08 .08 .08 .08 .08 .08 .08

84 .08 .07 .07 .07 .07 .07 .07 .07 .07 .0/

85 .07 .07 .07 .07 .07 .07 .07 .07 .07 .07

86 .07 .06 .06 .06 .06 .06 .06 .06 .06 .06

87 .06 .06 .06 .06 .06 .06 .06 .06 .06 .06

88 .06 .05 .05 .05 .05 .05 .05 .05 .05 .05

89 .05 .05 .05 .05 .05 .05 .05 .05 .05 .05

90 .05 .04 .04 .04 .04 .04 .04 .04 .04 .04

91

92.04

.04

.04

.04

.04

.04

.04

.03

.04

.03

.04

.03

.04

.03

.04

.03

.04

.03

.04

.03

93 .03 .03 .03 .03 .03 .03 .03 .03 .03 .03

94 .03 .03 .03 .03 .02 .02 .02 .02 .02 .02

95 .02 .02 .02 .02 .02 .02 .02 .02 .02 .02

96 .02 .02 .02 .02 .02 .02 .01 .01 .01 .01

97 .01 .01 .01 .01 .01 .01 .01 .01 .01 .01

98 .01 .01 .01 .01 .01 .01 .01 .01 .01 .01

99 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00

100 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 I

than once in the table, count from left to right working down the table, divide the number and use the

middle density figure. For example, the per cent, transmission of the density 0.44. which appears 9 times.

is 36.3 : the per cent, transmission of the density 0.32 is either 47.8 or 47.9.

85

APPENDIX

'KODAK' COMBINATION LENSATTACHMENT SYSTEM

The series of components and optical accessories comprising the 'Kodak'Combination Lens Attachment System provide for the " before-lens

"

requirements of the majority of cameras having lens mounts from 14 mm.to 83 mm. in diameter. By various combinations of the component partsof the system, provision can be made to accommodate 'Kodak' or 'Wratten'niters (see page 17), 'Portra' (close-up) Lenses, Lens Hood, etc., in frontof the camera lens.

The 'Kodak' Lens Attachment is the basic component by means ofwhichall lens accessories are held on to the camera lens mount. The mountingring at the back of this attachment is slotted to form broad claws whichslip firmly over the lens mount. A wide range of different claw-diametersare available, each of which can be varied by a few millimetres, to suit theindividual lens mount.

The front of the Lens Attachment has an internally threaded rim intowhich other metal components can be screwed—either on their own or,

more usually, securing a filter or supplementary lens. The threaded rimsare made in six different diameters ; this requires that the optical accessor-ies and components need only to be stocked in six sizes to fit any of theforty-six available lens attachments.

RANGE OF COMPONENTS

As a typical example, alternative combinations to fit a 1-in. (25 mm.)diameter lens mount are illustrated.

LENS ATTACHMENT

FILTER OR 'PORTRA- IENS

RETAINING RINC

'Kodak' Lens Attachment fits the lens mount.'Kodak' Filter or 'Portra* Lens, mounted in thinmetal rim.

Retaining Ring, in which the filter or 'Portra' lensis laid, screws into the lens attachment.

LENS ATTACHMENT

FILTER OR 'PORTRA' LENS Lens Hood can be fitted in place of the normalretaining ring. It may be either used alone onthe lens attachment or a filter or 'Portra' lensmay be placed in its recess before screwing it in.

LENS ATTACHMENT

Coupling Ring, fitted in place of the retaining

ring, will secure the 'Portra' lens or the first

filter and, by acting as a second lens attach-

ment, will take a second filter in a retaining

ring, or in a lens hood. All the components

of this combination will be in the same size

range.

No. ISO LENS ATTACHMENT

2S0 PORTRA' LENS

Step-up Ring, resembles the coupling

ring, but the components added to it

are of the next larger size. This enablesiso/320 step-up ring

a set of components of one size to be

used on a smaller size lens mount. Its

use is essential if a combination of

components all of one size shades

the corners of the picture. A filter or

lens of the smaller size may be secured

by the Step-up Ring.

No JJO LENS HOOD

86

AVAILABLE RANGE OF ' KODAK ' STEP-UP RINGS

Lens Attachment Step-up Ring Components

250

320

370

250/320

320/370

370/420

320

370

420

OPTICAL ACCESSORIES

•Kodak* and 'Wratten' Light Filters

These are available in the four standard sizes—250, 320, 370 and 420.'Kodak' Light Filters are available in four colours, yellow, green, orangeand red (see pages 89 and 90) and are specially fitted with thin metal rims tofit the lens attachment. Owing to the number of 'Wratten' niters availableonly the more popular niters are stocked in rims ; specialized niters are notnormally fitted with rims except to order. It is essential, therefore, whenordering 'Wratten' niters for use with the 'Kodak' Combination LensAttachment System, to quote the size of the attachment and mark theorder " with metal rim."

Note: Only 'Wratten' filters can be supplied to fit Lens Attachmentssize 651 and 826.

'Kodak' Portra Lenses

These single positive lenses can be fitted in front of the camera lens toreduce its focal length. They enable photographs to be taken with thecamera much nearer to the subject than would otherwise be possible, thusobtaining a larger image.

'Portra' lenses of powers of one diopter (+1), two diopters (+2) andthree diopters (+3) are available for use with 'Kodak' Lens Attachments.These are available in the four standard sizes :—250, 320, 370 and 420.

FOCUSING RANGES OF

CAMERAS FITTED WITH'PORTRA' LENSES

CameraSetting

Distance from lens to subjectin focus (to nearest inch)

+ 1 Lens +2 Lens +3 Lens

Infinity

SO feet

40 feet

25 feet

18 feet

15 feet

12 feet

10 feet

9 feet

8 feet

7 feet

6 feet

5 feet

4^ feet

4 feet

3± feet

39

37

36

35

33

32

30

30

29

27

27

26

24

23

22

20

20

19

19

19

18

18

17

17

17

16

16

16

15

15

14

13

13

13

13

13

12

12

12

12

12

12

II

II

II

10

10

10

Note : When a filter and 'Portra' lens are to be used together, the 'Portra'lens must be used immediately in front of the camera lens.

88

SIZE REFERENCE NUMBERS

The reference number of a Lens Attachment indicates the diameter of

the lens mount which it fits, and the size range of the components which

can be added to it. Six lens attachments have single reference numbers,

the rest have double reference numbers; the following two examples

illustrate their application.

1. A 'Kodak' 320 Lens Attachment fits a lens mount of 32 mm. external

diameter, and takes size 320 niters, lenses, lens hoods, etc. (Note

that a 320 filter is not itself 32 mm. in diameter. See pages 91 and 92.

2. A 'Kodak' 270/320 Lens Attachment fits a 27 mm. lens mount, but

takes size 320 accessories.

A lens mount for which no Lens Attachment of the exact size is available

can be accommodated by gendy bending inwards the claws of the nearest

oversize Lens Attachment. This can most effectively be done by rolling

the claws of the Attachment along a hard surface, keeping a firm and even

pressure. The claws should not be reduced in diameter more than 2 mm.(about l/16thin.). The claws should not be bent outwards unless

required to fit inside a lens mount.

The schedule below gives full information about the range of attach-

ments available and indicates alternatives for earlier type mounts which

are no longer available.

ABSORPTIONS CHARACTERISTICS OF 'KODAK' FILTERS

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The curves shown above and on the previous page give a fair indication

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