Photography

Crime scene photography, also known as forensic photography, is essentially the use of photographic methods and techniques to aid legal investigations. As well as creating a permanent visual record of the crime scene in the state in which it was originally found, forensic photographs will play a huge role throughout the entire investigation. They can act as triggers for both witnesses and investigators when trying to remember details of the event and scene. Such photographs will also be greatly beneficial in reconstructing the events which took place. Finally, the photographs taken at the scene can be called upon in court to support verbal and physical evidence, and give jurors a clear image of the crime.

How A Camera Works
A standard camera is composed of a number of basic components: a viewfinder, a focusing mechanism, a shutter, an aperture, a lens, the light-proof camera body, and numerous devices to control the settings. As light enters the camera through the lens aperture, it is reflected and the image recorded on the light-sensitive film loaded within.

The lens is the curved piece of glass through which the light passes to enter the camera, then being redirected to come together to form the image. Located between the front and rear lens is the aperture. This basically refers to the size of the opening in the lens, the feature controlling the amount of light entering the camera. Known as the f-stop or f-number, the larger aperture is F-2, and the smaller F-22, with numerous f-stops in between.

Covering the lens is the shutter, a feature controlling the amount of light allowed to focus on the film by determining the length of time for which the shutter remains open, measured in fractions of a second. If the shutter is opened for too long, too much light will enter the camera, and thus the film will be overexposed. Conversely, if too little light is allowed to enter, the film will be underexposed. The film is a silver-halide, light-sensitive medium onto which photographs are recorded. Numerous types of film are available, varying in their film speed, which is a measure of light sensitivity, and their colouring.

Techniques
With the exception of life-saving efforts, nothing should be moved or even touched at the crime scene until the forensic photographer has arrived. Extensive shots should be taken of the entire scene, ranging from overall, mid-range, to close-up photographs, including all items of significance and all entrances and exits. The various ranges used are necessary to first capture an object relative to its surroundings, and then document any details close-up. The exterior of the property should be documented from various angles, along with any noted scene irregularities. If there is a corpse at the scene, the victim will be photographed copiously in situ, with particular attention being paid to any injuries, weapons and personal items. It may also be advisable to photograph any crowds of onlookers gathering outside the crime scene, as members of the crowd may very well be implicated in the crime under investigation. Likewise, nearby vehicles can also be photographed. Scales will often be placed in the shot alongside the piece of evidence to provide immediate information regarding the relative size and position of objects.

The images taken at the scene may become the only visual proof of the crime scene as it was, therefore it is vital to maintain perspective in photos. Any distortion in images may compromise the image, making it useless in court. For each photograph taken the photographer must produce a log of relevant information, including a description of the photograph, from where the shot was taken, camera settings, and any enhancement techniques used, such as a flash or lens filters.

Generally, colour photographs will be produced, though on occasion black and white images may be beneficial for the purpose of enhancement. Various techniques are used during forensic photography to further enhance valuable pieces of evidence. Photomacrography uses extension tubes between the lens and the camera, allowing for an increased magnification that is particularly useful when documenting trace evidence such as fibres or glass fragments. Alternative light sources and different filters can visualise previously latent evidence, such as biological fluids.

Digital vs Film
Forensic photography began with the use of traditional wet photography, the use of a camera loaded with a light-sensitive film which was later processed in a dark room. However in recent years digital photography has also been adopted and in some cases preferred, due to its obvious advantages. The ease and convenience of digital cameras is particularly beneficial for crime scene photography, when images must often be captured as quickly as possible. With no need to carry, change and process rolls of film, images can be taken on the camera and immediately transferred to a computer or printer within minutes, eliminating the need to wait for dark room processing. For similar reasons, digital photography can be considerably cheaper if it is not necessary to spend money on rolls of film and dark room materials and processing. Digital methods can also reduce the risk of errors being made. As most digital cameras include an LCD screen on which stored photographs can be viewed, the photographer can view the image taken to ensure it has been recorded correctly before moving on. However some agencies do still work with traditional film photography, as digital methods do have their own limitations.