forensic photography 1

Forensic Photography 1The Basics of the Camera

Tuesday, January 8, 13

The Camera

film rewind crank

exposure control dial film advance leverflash hot shoe

f-stop ring

focusing ringlens

shutter release

ISO (ASA) dialshutter speed dial


Source: Michael Langford’s, 35 mm Handbook, pp. 24-25.


Source: Tom Ang, Digital Photography, pp. 18-19


Camera Nomenclature


Get Out Your Camera

• Locate Film Crank Lever – media slot lever• Open camera – open media slot, and access menu• Locate lens• Remove lens – attach lens• Locate f-stop ring – a menu item• Locate focus ring – locate adjustment control• Locate shutter control dial• Locate Film Speed Dial• Locate auto flash and manual flash


Adjust Your Camera

• Set camera to auto. (Look through the lens or at the digital display).

• Set camera to A and adjust shutter speed, then adjust ASA.

• Set camera to S and adjust aperture, then adjust ASA.

• Set camera to M, adjust aperture then shutter speed then ASA.


Photography

• Photography is the manipulation of light and the recording of the manipulation. (Miller, p.7)

• A camera is a device for the manipulation and recording of light.

• A camera can manipulate light in these ways: aperture setting (f-stop), shutter speed, film speed or digital ASA, lens, flash, filters, exposure control compensation.


Aperture

f 8

f 22

f 2


Aperture Settings

• The f number is the number of times the hole diameter (aperture opening) will divide into the lens focal length. The f 2 aperture diameter is ½ the focal length (Langford, p.33).

• The bigger the aperture number, the smaller the aperture diameter. An f 22 is a smaller opening than an f 2.

• Aperture is important for control of amount of light and depth of field.

• Depth of field refers to the distances in which objects are in focus.


Depth of Field

objects in focus at 2-3m, or 8 feet

objects in focus .7 to .5 m


F-stop Settings

Source: Larry L. Miller, Police Photography, p. 15.


Depth of Field Practical

• Focus on an object.• Set your aperture to 2 or nearby. At what range are objects in

focus?• Set your aperture to 8. At what range are objects in focus? • Set your aperture to 22 or nearby. At what range are objects in

focus?• You have focused on an object at 15 feet. What should be your

aperture setting so that the object is in focus and all objects from 8 feet to infinity are in focus?

• Tech note: Each f-stop from bigger to smaller number doubles the amount of light let into the camera. From f-16 to f-11 doubles the amount of light. From f-16 to f-8 lets in four time the light.


Shutter Speed

• This is the amount of time the shutter is open. In other words it is the amount of time light reaches the film or sensor plane.

• The shutter speeds are given in seconds (30, 8, 4, 2, 1) and factions of a second (1/30, 1/125, 1/60, 1/1000).

• As a general rule, 1/60 second is the slowest you can hold a camera to avoid blur.

• As a general rule, 1/1000 second is sufficient to stop action on a moving object such as a running person.

• As a general rule, 30 seconds is sufficient for recording a luminol or fluorescent image at f-8.

• Most flashes synchronize at 1/60 or 1/125.


The Shutter Plane

Align lens

Timer


Shutter Speed


Shutter Speed Practical

• Set your camera to S or P. This is the shutter priority. Look through the lens and focus on an object.

• Change the aperture. What happened to shutter speed?

• Set your camera to manual. Set the aperture to f-16 and the shutter to 1/1000. Focus on the wall the carpet. Focus on the front wall. When were you over or under exposed?


Loading the Recording Medium.

• For 35 mm cameras lets talk film. Film is rate with a number. It most often is like 100, 400, 800 or 1000. This indicates how sensitive the film is to light. The 100 film called ISO 100, is less sensitive than the 400, called ISO 400. In days past the film was rated as ASA 100 or Din 24, as an example. So, old timers like me talk of ASA. Today the film has been standardized to an ISO number. Photographers talk about these number in terms of film speed.

• The lower number film records more detail sharper and with greater color distinction. Photographers say that the film is less grainy and better balanced.


ISO Film Setting


Film

Film speed


Digital “Film”

Source: Tom Ang, Digital Photography, pp. 20-21


Loading the Recording Medium

• For digital cameras lets talk recording medium. This means card or disc.

• For the most part leave the digital camera ISO (ASA) setting on auto.

• Locate your setting control button: for 35mm and digital.

• You can change the ISO setting for either camera. Are you having trouble? Look in the owner’s manual.


ISO Practical

• Set your camera to automatic.• Note the shutter speed and f-stop.• Set your camera to manual. Set the shutter speed to

1/125 or close.• Adjust the ASA (ISO) setting. What happens when you

increase the ISO setting?• If you want to keep the f-stop at f-16, and 1/500

shutter speed but you are under exposed and you have a film speed rating of ISO 100, what can you do to be able to keep the settings at f-16 and 1/500 with a properly exposed image?


Aperture, Shutter, ISO

• The three work together. Usually you chose the ISO film speed prior to the other two.

• ISO of 400 is very good forensic photography filed film speed. ISO 100 works well but you sometimes run into light problems indoors, evenings and nights. You can push ASA 400 up to 800 ASA with some success.

• Always maximize depth of field. As a general rule get the most depth of field with the fastest shutter speed. We are talking forensic photography.

• You can help shutter and aperture by moving the camera, called panning, with the object and by shooting into bright light or a bright background.


Shutter, ISO, and Auto ISO

1/30, f 2.0 8’, f 8.0

1/500, f 2.8 1/1000, f 8.0 1/1000, f 2.5

1/30, f 8.0


The Flash


Flash Practical

• Set your camera to auto flash.• Set your camera to manual flash.• Disable the flash.• Connect your flash off camera.• Focus on the wall. What distance should you set

your flash?• Focus on the floor. What distance should you

set your flash?


The Tripod


Tripod Practical

• Using normal position, connect the camera to the tripod.

• Level the tripod.• Connect the camera to take a photo of a shoe

print. Set the camera focal plane at 2 feet.• Set the camera to take a photo of an object on

the wall. Set the camera focal plane t 2 feet.


The Accessories

Flash cord

Shutter release

shutter release cable

level

scale


Remote Operation Practical

• Set up flash with remote cord.• Set up shutter release with remote cable.• Set up shutter release with timer.• Check camera for correct settings. -ISO100, flash, f 5.6 -ISO400, 30, f 16• Level and secure camera.• Take photo.


Filters


Holding the Camera

Very Good!! Not so very good!!


Resources• Ang, Tom. Digital Photography: An Introduction.

New York: DK Publishing, , Inc., 2003.• Langford, Michael. 35mm Handbook. 3rd ed. • New York: Alfred A. Knopf, 2002.• Miller, Larry L. Sanone’s Police Photography. 3rd ed.

Cincinnati, OH: Anderson Publishing Co., 1993 .• Staggs, Steven. Crime Scene and Evidence

Photographer’s Guide. 2nd ed. Wildomar, CA: Staggs Publishing, 2004.


Break Time


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