Forensic Photography and Imaging
Forensic Photography and Imaging
This domain tests whether you can produce accurate, reproducible images of a scene and evidence: exposure control, lighting, scale placement, perspective, and documentation of every capture and enhancement.
Core rules
- Exposure triangle: aperture controls depth of field, shutter speed controls motion, ISO controls sensitivity and noise. For evidence, use low ISO and a small aperture on a tripod.
- Photograph every item in three stages: overall for context, midrange for relationships, close-up for detail with a scale.
- The scale must lie in the same plane as the evidence and be readable; place it adjacent to, not covering, the item.
- Use oblique or raking light for impressions, indented writing, and surface texture; use diffuse light for color and pattern.
- Record camera, lens, settings, lighting, and distance in a photo log. Preserve originals; document any enhancement and retain the unaltered file.
Worked example
A latent print on a dark glass table. Set the camera on a tripod directly above, parallel to the surface. Use f/11 to f/16 for depth of field, ISO 100, and a remote release. Illuminate from a low angle with a fiber-optic light or torch to create shadow in the ridges, not a direct flash that creates a hotspot. Place an L-shaped scale at the print's edge in the same plane. The reasoning: a parallel sensor and raking light maximize ridge contrast and avoid perspective distortion; a scale out of plane cannot support a 1:1 comparison.
Traps
- Flash hotspot or reflection hiding detail.
- Scale tilted or not in the focal plane.
- Only close-ups, with no overall image.
- Cropping or altering the original without documenting it.
- Missing photo log entries.