CFP Forensic Photographer Lighting Techniques & Digital Processing 3 — Questions and Answers
Question 1: A photographer must document a fingerprint developed with fluorescent powder. After exciting it with an ALS, why must the exposure typically be increased?
- Fluorescent emission is much dimmer than reflected light (Correct answer)
- Barrier filters double the light reaching the sensor
- The camera meter overexposes fluorescence automatically
- Fluorescent powder reflects ultraviolet only
Correct answer: Fluorescent emission is much dimmer than reflected light
Fluorescence emits far less light than normal reflection, so longer exposures or wider apertures on a tripod are usually required.
Question 2: Which technique best documents an indented writing impression on a notepad recovered from a suspect's desk?
- Direct on-camera flash from the front
- Oblique lighting raked across the page at a low angle (Correct answer)
- Backlighting through the page
- High-key diffuse lighting from all sides
Correct answer: Oblique lighting raked across the page at a low angle
Low-angle oblique light casts shadows into the shallow indentations, making the impressed writing legible.
Question 3: When photographing through a vehicle windshield to capture interior blood spatter, which accessory most effectively reduces reflections?
- A UV haze filter
- A circular polarizing filter rotated to cancel the glare (Correct answer)
- A neutral density filter
- A close-up diopter lens
Correct answer: A circular polarizing filter rotated to cancel the glare
A polarizing filter can be rotated to block polarized reflections off glass, revealing detail behind the surface.
Question 4: Under SWGDE/SWGIT guidance, which digital processing action on evidentiary images is generally considered unacceptable?
- Global brightness and contrast adjustment documented in notes
- Cropping that is documented and preserves the original
- Cloning or content-aware removal of visual elements from the image (Correct answer)
- Converting a documented working copy to grayscale
Correct answer: Cloning or content-aware removal of visual elements from the image
Removing or adding image content alters the factual record, unlike documented global adjustments that only improve visibility.
Question 5: Why should the original memory card image files be write-protected and hashed immediately after a scene is photographed?
- To compress them for archiving
- To establish integrity and prove images were not altered after capture (Correct answer)
- To embed GPS coordinates
- To improve playback speed in court
Correct answer: To establish integrity and prove images were not altered after capture
A cryptographic hash of the originals establishes a verifiable baseline proving no post-capture alteration occurred.
Question 6: A photographer shoots a luminol reaction in a darkened room. Which combination is most appropriate?
- Tripod, high ISO, long exposure of several seconds to minutes (Correct answer)
- Handheld with on-camera flash at full power
- Fast shutter of 1/1000s to freeze the glow
- Small aperture f/22 with default auto settings
Correct answer: Tripod, high ISO, long exposure of several seconds to minutes
Luminol chemiluminescence is extremely faint and short-lived, requiring a stabilized long exposure at elevated ISO in darkness.
Question 7: What is the effect of using a light source with a high color rendering index (CRI) when photographing trace evidence like fibers?
- It shortens flash duration
- Colors are reproduced more accurately, aiding later comparison (Correct answer)
- It eliminates the need for scale references
- It increases depth of field
Correct answer: Colors are reproduced more accurately, aiding later comparison
High-CRI lighting renders true colors, which is critical when fiber or paint color may be compared to known samples.
CFP Forensic Photographer Lighting Techniques & Digital Processing 3
A photographer must document a fingerprint developed with fluorescent powder.
After exciting it with an ALS, why must the exposure typically be increased?