Forensic Photography and Imaging
The Forensic Photography and Imaging domain tests technical camera control plus the ability to produce accurate, reproducible, court-defensible images. Expect exposure calculation, lighting selection for specific evidence types, scale discipline and digital image integrity.
Exposure control
- The exposure triangle: aperture (f-number controls depth of field), shutter speed (controls motion), ISO (controls sensitivity and noise).
- Reciprocity: f/8 at 1/125 s is equivalent to f/11 at 1/60 s; adjust one stop at a time and record settings.
- Meter for the evidence, then bracket where contrast is extreme.
Lighting choices
- Oblique or raking light reveals indented writing, tool marks and latent prints on non-porous surfaces.
- Axial lighting suits reflective and specular surfaces; diffuse light suits overall and injury photography; backlight suits transparent and translucent items.
- Painting with light and fill flash extend range in large or dark scenes; barrier filters pair with alternate light sources to block excitation light.
Scales and integrity
- ABFO #2 for patterned injury and bite marks; L-scale for general work; scale in the same plane as the subject, labelled with case number and date.
- Capture RAW where available, avoid digital zoom, and record any enhancement step.
Worked example. A latent print on dark glossy tile: mount the camera on a tripod, set ISO 100 and f/11 for depth of field, focus manually at 1:1 reproduction, place an L-scale beside the print, and rake a white light at a shallow angle to graze the ridges. Bracket exposures and keep the RAW files untouched.
Traps that cost marks
- A tilted or out-of-plane scale, which invalidates later measurement.
- Camera or photographer shadow falling across the evidence.
- Overexposure clipping highlight detail irrecoverably.
- Archiving only compressed JPEG files.
- “Enhancement” that fabricates detail rather than revealing it.