CFP Forensic Photographer Lighting Techniques & Digital Processing 2 — Questions and Answers
Question 1: When photographing a dusty shoe impression on a tile floor, at what approximate angle should oblique lighting be positioned to maximize detail contrast?
- Directly overhead at 90 degrees
- A low angle of roughly 10-15 degrees to the surface (Correct answer)
- 45 degrees with a diffuser
- Behind the camera at eye level
Correct answer: A low angle of roughly 10-15 degrees to the surface
Low oblique lighting at about 10-15 degrees rakes across the impression, casting micro-shadows that reveal ridge and tread detail.
Question 2: Which light source is most effective for visualizing untreated latent biological stains such as semen at a crime scene?
- Infrared flood lamp
- Standard tungsten spotlight
- An alternate light source (ALS) in the 450 nm range with an orange barrier filter (Correct answer)
- Ring flash mounted on the lens
Correct answer: An alternate light source (ALS) in the 450 nm range with an orange barrier filter
Many biological fluids fluoresce under blue light around 450 nm, and the orange filter blocks the excitation light so only the fluorescence is recorded.
Question 3: A forensic photographer uses painting with light at a large outdoor nighttime scene. Which camera setting combination is required?
- High ISO, fast shutter, wide aperture
- Camera on tripod, shutter locked open on bulb, low ISO (Correct answer)
- Handheld camera with image stabilization and auto ISO
- Burst mode with TTL flash
Correct answer: Camera on tripod, shutter locked open on bulb, low ISO
Painting with light requires a tripod-mounted camera with the shutter held open while the photographer walks the scene firing multiple flash bursts.
Question 4: Why is bounce flash often preferred over direct flash when photographing a bloodstain pattern on a glossy painted wall?
- It increases the flash recycle speed
- It eliminates specular hotspot reflections that can obscure detail (Correct answer)
- It produces harder shadows for depth
- It raises color temperature to daylight
Correct answer: It eliminates specular hotspot reflections that can obscure detail
Bouncing the flash off a ceiling or card diffuses the light and prevents specular glare from the glossy surface from washing out the stain detail.
Question 5: In digital processing of forensic images, what is the primary purpose of maintaining an audit trail of enhancement steps?
- To reduce file storage requirements
- To allow another analyst to reproduce the same result from the original image (Correct answer)
- To speed up batch processing
- To automatically sharpen future images
Correct answer: To allow another analyst to reproduce the same result from the original image
SWGIT-based best practice requires documented, repeatable processing so any qualified examiner can reproduce the enhancement from the original.
Question 6: Which histogram condition indicates a properly exposed photograph of a dark-colored firearm on a dark surface?
- All tonal data pushed against the right edge
- Data clipped hard against the left edge
- A distribution weighted left but with no clipping at either edge (Correct answer)
- A perfectly symmetrical bell curve centered at middle gray
Correct answer: A distribution weighted left but with no clipping at either edge
A dark subject legitimately produces a left-weighted histogram, but clipping at either edge means detail has been irretrievably lost.
Question 7: What is the main advantage of capturing forensic images in RAW format rather than JPEG?
- RAW files upload faster to evidence servers
- RAW preserves all sensor data without lossy compression, allowing non-destructive adjustment (Correct answer)
- RAW images are automatically color corrected
- RAW files cannot be opened by defense experts
Correct answer: RAW preserves all sensor data without lossy compression, allowing non-destructive adjustment
RAW retains the full unprocessed sensor data, so exposure and white balance can be adjusted without the compression artifacts and data loss of JPEG.
CFP Forensic Photographer Lighting Techniques & Digital Processing 2
When photographing a dusty shoe impression on a tile floor, at what approximate angle should oblique lighting be positioned to maximize detail contrast?