Forensic Photography Rules and Special Techniques

Forensic photography is governed by cardinal rules essential for accurate documentation of evidence.

Photograph with intent to convey the main subject clearly.
Primary subject can include context, not just items.
Maintain clarity in both foreground and background, relating to depth of field.
Do not reposition moved or altered items; photograph the scene as it is and note alterations in case notes.

Identify the primary subject of the photograph and ensure it fills the frame.
Important for close-ups; eliminate irrelevant background elements.
Utilize appropriate viewpoint; maintain horizontal or vertical camera orientation.
Do not cut off parts of the subject; photograph the entirety of it.

Definition: Depth of field is the distance between the nearest and farthest objects that appear sharp in an image, sometimes referred to as the zone of acceptable sharpness.
Goal: Increase sharpness to create a true representation of evidence.
An improper depth of field can distort evidence; improper focusing may appear sharp to the human eye, even if it is not sharply captured.
Increase or decrease depth of field by adjusting the f-stop of the camera.

Applies to all photographs; particularly critical in close-ups.
The film plane (back of the camera) must be parallel to the subject at a 90-degree angle to avoid distortion.
Holding the camera at an angle can lead to unintended distortions in photographs.
Example: Properly oriented camera helps in accurate representation, while an angled camera may look distorted even if not visibly recognized.

The scale should always be on the same plane as the evidence it relates to.
Allows for accurate size representation; if focused on a specific point, the scale must be at that same level.

Use props like lens caps, coins, or paper to elevate the scale.
Strategies for ensuring the placed scale does not appear in the photograph, which requires planning.
Special consideration for scenarios like shoe prints in dirt, where the depth of the scale must match the depression of the print for accurate life-sized comparisons.

Use of alternative light sources provides clarity that standard lighting may miss.
Techniques include:
- Oblique Lighting: Angling a flashlight across the evidence smoothly highlights three-dimensional details (e.g., footwear impressions).
- Use of ultraviolet or fluorescence to better capture hidden details (e.g., bruising, blood impressions).

Photography enhancements under different light conditions reveal hidden evidence not visible under standard settings.

Enhancement methods can aid in revealing crucial evidence:
- Leuko Crystal Violet: Enhances blood impressions.
- DFO (1,8-Diazafluoren-9-one): Fluoresces latent fingerprints on porous surfaces under blue-green light.
- Colored Filters: Used to isolate specific features in evidence photography.

Operates beyond human vision (720 - 800 nm) to reveal latent tattoos or branding invisible under standard observation.
Absorption of infrared radiation by ink reveals images that would typically go unnoticed, providing useful forensic insights.

Forensic photography requires extensive training, practice, and mastery of numerous skills.
Overlapping concepts highlight their interrelated importance in developing expertise.
Emphasis on continual practice to internalize techniques for improved photographic quality.