Cameras

A classical image of a crime or accident investigation involves an investigator photographing the scene. Cameras are vital to forensic science, providing a visual record of the scene. For example, a picture of a blood spatter can be used to help determine the cause of the spill long after the stain itself has been cleaned away.

A visual image is an ideal way to preserve a record of a scene before items are disturbed. Pictures are admissible as legal evidence, providing the prosecution or jury members with an evocative image of the scene. Visual images can aid in reaching a verdict on a crime.

A traditional camera functions by focusing light through a lens onto a surface coated with light-sensitive chemicals. Digital cameras have internal processors that record images in an electronic form, converting wave-like analog information into digital information represented by bits. The concept of the camera dates back to the Renaissance idea of the camera obscura, a small, dark chamber into which light was permitted only through pinholes. During the early nineteenth century, inventors perfected the camera obscura to make the prototype of the modern camera, but early photography was a cumbersome affair characterized by large, boxy cameras and slow exposures.

Surveillance cameras, which have long been an espionage tool, can also be a useful forensic tool. According to the Security Industry Association, by 2003 there were some two million closed-circuit television systems in operation, most of them operated by private businesses for security purposes, in the United States. Many households are also equipped with surveillance cameras.

A forensic investigator can gain legal access to the recordings made by a security camera. This can provide vital information of events before, during, and following the crime or accident.

Increasingly, municipalities are installing surveillance cameras at traffic intersections to monitor the license plate numbers of traffic violators. Such data can be useful forensically.

Virtually all traditional cameras have at least one glass lens, and one with a zoom or telephoto lens typically has three: front and rear convex lenses, with a concave one in between. Though zoom lenses clearly have an application in the world of law enforcement, they can also provide long-distance photos that are useful in a forensic investigation. Miniature and subminiature cameras are usually for photographing images at close range. Typically they would have only a single lens, perhaps with a coating to reduce reflections or glare.

In place of lenses, a pinhole camera uses tiny apertures, or openings, so small that they are known as pinholes. The value of a lens lies in its ability to focus and thus photograph distant objects or ones close by, depending on the settings. By contrast, the value of a pinhole camera is precisely the fact that it does not have lenses, and therefore can produce images of distant and nearby images equally well.

Forensic photography is typically the responsibility of a skilled photographer. The photographer will be careful to photograph the subject from a variety of angles and to use lighting conditions that will emphasize all the detail of the object.

Digital cameras can be useful, since the digitized information can be downloaded to a database for further scrutiny. But, even traditional film photographs can be digitized for electronic storage and analyses.