Forensic Photography: Viewing the Final Product

Forensic photography is used by private investigators to create a complete and accurate picture of a scene or object in an effort to aid during an investigation and serve as admissible evidence in a court of law. The science of forensic photography is complex and detail oriented in nature. Private investigator working as forensic photographers must use various types of equipment to capture and produce images. This includes multi-functional cameras, computers, an array of different-sized lenses and other related visual equipment. They also must take into account several physical factors, such as distance, perspective, lighting, angles and use of scales.
Forensic photography is used by private investigators to create a complete and accurate picture of a scene or object in an effort to aid during an investigation and serve as admissible evidence in a court of law. The science of forensic photography is complex and detail oriented in nature. Private investigator working as forensic photographers must use various types of equipment to capture and produce images. This includes multi-functional cameras, computers, an array of different-sized lenses and other related visual equipment. They also must take into account several physical factors, such as distance, perspective, lighting, angles and use of scales.

Two of the physical factors crucial to the forensic photography process are distance and perspective. (The distance from which a photograph is viewed, and the perspective viewpoint that is conveyed within an image along with the context it provides.) Accurately capturing, producing and viewing the distance and perspective of a scene or object within an image is an intricate and complex task. While human eyes are incapable of zooming in and out on objects within an image, forensic photographers with multi-functional camera and computers are able to create this effect.

Humans are only able to perceive the perspective of a scene at one magnification, unless they move physically closer or farther away from the scene. The most comfortable distance for an individual to view an image is 14 to 15 inches away from the eye. This is what is considered to be “normal viewing distance.” The proper viewing distance in inches for any print is equal to the focal length of the camera lens in inches times the enlargement factor of the print. In order to accommodate normal viewing distance and also achieve maximum detail and clarity, forensic photographers rely on the process of magnification.

Magnification is an excellent process used to enlarge the appearance, but not actual size of an object. While camera lens do not necessarily capture images of a visual scene at the same magnification as human vision would, it does serve as a useful aid. Unfortunately, there are some drawbacks that a forensic photographer must be aware of when magnifying an image. The magnification of a given scene may distort the image’s perspective. The magnification itself will also change if the image is printed in various sizes. While magnification is an excellent tool for achieving greater detail and clarity within an image, the integrity of scene or object’s perspective must also be maintained.

In order to combat perspective distortion of magnified images, forensic photographers must utilize tools to correct for this. One method for maintaining the perspective integrity of a magnified image is to divide 14 by the focal length in inches of the lens used to make the image, then multiply the result by the crop factor for the sensor and finally enlarge the image to the resultant number. During the magnification process, images must also remain clear and sharp. If a image taken through 35mm lens is enlarged to an 8X10, a point on that image should be no larger than .25mm or .001 inches to preserve sharpness.

Forensic photographers must take great care to accurately capture, produce and view a crime scene image. Like any scientific procedure, rules must be applied and tools employed to preserve the integrity of an image. Forensic photographers must effectively convey distances and perspective within crime scene images, so that the evidence serves as an aid to law-enforcement and is admissible in a court of law.


Pennington & Associates ltd. provides
forensic photography services. Private investigators are available for immediate service in Ohio throughout the cities of Ironton, Portsmouth, Gallipolis, Jackson, Chillicothe, Cincinnati, Columbus, and surrounding areas. Service is immediately available in West Virginia throughout the cities of Huntington, Charleston, and surrounding areas.
blog comments powered by Disqus