Best Practices For Photographing A Crime Scene

Best Practices for digital photography are procedures and rules that allow Crime Scene Investigators the ability to take clear meaningful photographs of items located at the crime scene. Four important photographs are explained fingerprints, shoe prints, tire marks, and bit marks.

Image resolution and clarity is a must, filling the frame is an important first step in taking good photographs. The digital cameras frame should be dedicated to the object improving both quality and size this makes for a better photograph by getting the highest quality view as possible.

When capturing finger prints and bite marks the lens should be set to the closet focusing distance. Next move the camera as close to the object as possible. Then capture the object in a precise one to one using the highest resolution.

Set the closes focusing distance by using the lens on the camera. Use by accurately calibrating the image by scale using Adobe Photoshop.

Capturing shoe prints and tire marks is a process that consists of taking full length photographs while filling the frame and adjusting the resolution for the sharpest image as possible.

It is correct to have image quality suggesting that you take pictures in segments that overlap then stitch or panorama the photographs together to provide an accurate view of the shoe print or tire marks.

These photographing techniques help the CSI agent take realistic photographs that represent objects as they appear at the crime (situ). The processes involved in best practices allow for the photograph examiner to see an actual representation of the object being photographed as close to its full size and length as possible.

References:

Crime Scene Photography Author: Edward M. Robinson with forward by Gerald Richards Publisher: ELSESEVIER Copy right: 2007

http://www.adobe.com/products/reader/pdfs/reader_user_guide.pdf

Depth of Field

Depth of field allows you to photograph the whole subject matter while keeping the actual focus on the single object. Many photographs will not allow you to take pictures of a single object with distractions in the way moving people, cars, trees, bushes, other photographers, it helps to find a good angle to take photographs from afar while keeping your objective centered. Some of the best pictures use depth of field for objects that either do not fit within regular lens size or need modification to view the whole subject matter. Magnification of the lens plays a big role in focusing  the camera to have depth  of field, another factor of depth of field are the f /stop setting they allow you to view the photograph in the correctly  lighting. Crime Scene investigators should not leave any object out of focus this technique is only used for photographers that take pictures for leisure or sales purposes. All photographs for Crime Scene Investigator must be in focus and directed to the subject matter. 

References:

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

http://www.photoxels.com/tutorial_dof.html

http://www.photoaxe.com/depth-of-field-photography-tutorial-part-3/

Night Photography Available Light

When photographing in dark places to add to the reflective surfaces it is suggested that you use a white card board or matte board, white projection screen, or a small white umbrella in order to catch light and refract it back to the camera.

Bracket your shoot, meaning take multiple photographs with different settings until you accomplish your goal. Take one shot at basic and then another shot with open lens.

Available light sources at night include:

·         Incandescent light

·         Halogen light

·         Mercury vapor

·         Fluorescent

·         Spot light

·         Arc light

·         Artificial light

Many SLR cameras have special flash settings for night view. Using an external meter such as a Gossen, it has the capability to read light from the moon and gives exposure based on natural gray card.

For special effects and movement photographs at night use a low power flash, make proper settings  f/4 and the back ground requires an exposure of 1/30, at F/2  and background requires an exposure of 1/8^th setting, shoot  as steady as possible.  

Having knowledge of how to work your camera is important, the user manual of the specific camera and flash allows you to know how to use your flash shader for moving objects. It is a nice feature to have an off the camera flash with night exposure settings that works by a remote system, this way you can move the flash lighting to the proper area to expose light from the background of the photographed object or person thus adjusting white light and soft light exposures producing a better photograph. 

Usage of the windows and door passages as a way to produce refractive light around the room is a good way of producing light in dark areas; using the white card board and white screen help make dark surfaces more refractive and noticeable. I know that the night settings and the built in moon light detection system in my Nikon D3000 works great but it only works properly with the SB 300 flash system.

References

Article by Robert Gorril Available Light and Night Photography in color and Black & White located at http://psa-newmember.org/firstyearhappenings/nightphotography/available-light.pdf also found at http://www.thefreelibrary.com/Available+light+and+night+photography%3A+in+color+and+black+%26+white.-a090219328