By Stan Cusumano

Ignorance and apathy are allowing thousands of photographs to be used as evidence in our courts on a daily basis. Almost everyone has a camera and can “take” a photograph. Most attorneys think that rather than hiring an expert to perform the needed services, in an unbiased manner, they can do just as good a job themselves, or worse yet, simply tell the client to “get a few snapshots.”

Probably the most commonly used piece of evidence in today's law practice is the photograph. All that is presently required for a photograph to be entered into evidence is to have the witness testify the photograph is a “fair and accurate representation” of what it depicts.

This is an oversimplified demand to make of a document containing critical variables such as film selection, lighting, color, angle of view, angle of coverage, selective focusing, speed of moving objects, compaction and expansion of objects and time, magnification and reduction, and even a potential of depicting things that cannot be seen with the human eye!

The problem is serious. If any one of the above variables is incorrectly set forth, the photograph becomes misleading. If you have gone to the movies lately, you can readily see that just about anything can be done with a photograph to make it extremely believable, yet totally false. The important point is that “all photographs of any kind are always distorted relative to reality.” It is the experts' responsibility to understand those distortions and explain them properly so the untrained observer will interpret them properly.

Photographs made at normal distances from scenes, people, or objects are “representations” ; that is, they represent the three-dimensional world in two dimensions. Given the fact the photograph has been properly exposed, well-lighted, and otherwise technically correct, most people can interpret what they see. But this interpretation of ”fair and accurate” may be contested in a case.

One of the easiest ways of contesting a photograph is by requesting the parties set forth the proper viewing perspective for the photograph. When a photograph is intended to show relative distances or sizes of objects, it is paramount the picture be viewed at the correct distance or it will be totally misrepresentative.

Consider the geometric relationships between the camera and an object at the time a picture is taken. From a fixed vantage point, an object or series of objects, intercept the same angle at the lens regardless of the focal length of the lens. The objects are simply rendered larger or smaller, depending on the focal length of the lens. If this same angular relationship is reestablished between the finished photograph and the viewer's eye, the print will be viewed correctly and the eye will “see” the scene in true perspective.

In more simple terms, the photograph would act as an overlay if it was taken out to the scene and held up to your eye. If you hold the photograph too close to your eye, the objects in it appear to be larger than they actually are, and if you hold it too far from your eye, the objects appear to be smaller than they actually are in real life.

Mathematics has given us a formula to obtain the correct viewing distance of any photograph. Simply put, the correct distance is equal to the lens' focal length multiplied by the number of times the negative is enlarged. Although this relationship defies correct viewing distances for true perspective, we must consider the comfort of the viewer and the way in which the prints will finally be viewed. Prints for courtroom use, for example, will usually be hand-held. According to vision tests, the average person holds a reading object about 15 inches (about 40 centimeters) from his eye. This distance is widely accepted as the “normal viewing distance” for hand-held materials. This distance must be considered when determining the degree of enlargement needed for true perspective.

Before you “stipulate” or agree the photographs “depict a fair and accurate representation”, request the important information of the type of camera, the focal length of the lens, and the degree of enlargement, so you can be assured the proper perspective has been obtained.

The next time you hear the adage “photographs never lie,” disregard it. A camera in the hands of a liar will speak as does its master.