Introduction to EngineeringCamera Lab #3 - 1

Agenda Do parts I and II of the labRecord dataAnswer questions

Tasks I & II

Objective: Determine some characteristic quantities

associated with the camera. The focal length (TASK I). The near and far focusing distances (TASK II).

Focal Length

ab / AB = f/Hf = (H * ab) / AB

ObjectA B

O

ab

H

f

Image

Imaging Configuration (Top View)

Task I

Task I

Pick the best central image.Measure “ab” (using the loupe).Each group member should measure the

length of the subtense bars.Try not to be biased by the previous

measurements in your group.

Lens

x f f' x'

s s'

L

P

P'

y

y'

F F'

t

H H'

NN'

Lens Equation

The lens equation relates the focal length (f), the image distance (s`) and the object distance (s).1/f = 1/s + 1/s`

Depth of Field

Depth of FieldThe distance in the object space within which the object point can be moved and still be in acceptable focus.

AF

A

AN

A

pA qA

Depth of field Image plane forobject point A

aN

a

af

c

c

Circle of confusion same size at both apertures

Factors Affecting Depth of Field

The focal length (f).The object distance (s).The diameter of the aperture stop (D).

The smaller the aperture the larger the depth of field and focus.

The radius of the acceptable circle of confusion (u).

Task II

Sn & Sf → S. S & f → S`. S , S`& u → f/D (D is the diameter of the

aperture). Compare the estimated diameter of the

aperture with diameter of physical aperture. Change Sn & Sf until you get a reasonable

diameter of the aperture

Photography

A

a

C

c

B

b

D

d

Lens

Image Space

Object Space

Assignment

Read Parts III, IV, and V of the Camera Lab #3 procedure.

Think about answers to the questions in those parts.