Iowa Division
International Association for Identification
Photographic Techniques:
Considerations for Back Lighting
Detective Robert E. Kramer
Police Division - 220 Clay Street
Cedar Falls, IA 50613
(319) 268-5132
cfpdlab@mchsi.com
Law enforcement officers are often confronted with lighting situations which make it necessary to employ special techniques for proper exposure of the film and illumination of the subject matter. One of the problems of which I speak is the problem with back lighting. Back lighting causes problems for the law enforcement officer when strong influential light is coming from behind (or in back of) the subject matter. Harsh back lighting often causes the side of the subject matter facing the camera to be dark. If the subject being photographed is in the shadow (dark side), or, if the subject matter is the shaded side itself, steps need to be taken to illuminate the side of the subject matter which is being influenced by the back lighting.
A very simple way of understanding a harsh back-lit subject can be done by viewing the illustrations shown below. In the first photo (shown by "clicking" immediately below), I allowed my camera (under the "Programmed Mode") to pick an f/stop and shutter speed for me. What we need to understand, though, is that the camera is being influenced by the harsh light coming through the window behind the subject matter. This, quite obviously, is an unacceptable photograph. As I stood in front of this young lady, I could clearly see her face as we prepared to demonstrate what I have illustrated. What I also knew was that my camera (the film, actually) cannot see what I see. With the camera on the "Programmed Mode" I knew that the chosen camera settings would be insufficient to illuminate the front of the subject.
Click to view Diana as a backlit subject
I obtained a better photograph (shown below) by first recognizing the problem that there was in fact harsh back lighting present in the scene. Knowing that the subject matter was going to be terribly underexposed, I chose to illuminate the front of her face with the aid of an electronic flash. It was that simple.
Click to view Diana as a backlit subject with flash
For those of you wondering, the first photo was taken using AGFA 100 asa color film, exposed at f/11, 1/125th sec. The second photo was taken with identical camera settings, suplemented with an electronic flash calibrated for a six-foot range.
