FS - Week 8 Lecture Notes

Comprehensive vocabulary flashcards covering the principles, equipment, lighting methods, procedures, and specialized techniques of forensic crime scene photography.

Forensic Photography

An investigative and recording tool used to jog memory, document transient evidence, establish item placement within a crime scene, and support verbal and physical evidence in court.

Running Log

A mandatory court documentation record accompanying digital photographs that logs when, where, and by whom each photo was taken, matching the digital metadata stored on the camera or storage drive.

Standard Operating Procedures (SOPs)

Established protocols that ensure forensic photos follow a sequential order, logs match camera data, security software restricts access, and original photos are preserved as read-only.

$45^\circ$ Lighting

A photographic lighting method utilizing $1\text{--}2$ light sources positioned at a $45^\circ$ angle to minimise shadows, most commonly employed to capture the shape and size of evidence.

$10^\circ$ Lighting

An almost vertical lighting technique that casts virtually no shadows and suppresses surface texture.

Oblique Lighting

A low-angle illumination technique that casts shadows across a surface to reveal fine three-dimensional detail, impressions, or texture.

Bounce Lighting

A technique where illumination is reflected off an intermediary surface before striking the subject, providing soft, non-glare lighting with low contrast.

Diffused Lighting

A technique that shines light through a translucent material to soften illumination and reduce harsh specular reflections on shiny evidence.

Transmitted Lighting

An arrangement where illumination is transmitted directly through transparent or translucent evidence to create a clean, shadow-free background.

Normal Lens

A camera lens with a standard focal length of $50\,\text{mm}$ that reproduces scenes with regular human perspective.

Wide-Angle Lens

A short focal length lens (such as a $28\,\text{mm}$ lens) utilized for capturing broad scenes, confined spaces, or small rooms.

Focal Length

The distance between the optical center of the camera lens and the image sensor; larger lenses have longer focal lengths.

Working Distance

The physical measurement of space between the front element of the camera lens and the subject being photographed.

Reversing Lens

A lens mounted in reverse onto a camera body to switch its optical configuration from reducing an image to magnifying close-up subjects.

Aperture

The variable opening inside a lens controlled by a metal diaphragm that determines the amount of light passing to the sensor.

f-stop

The ratio setting indicating the relative aperture size; a higher f-number corresponds to a smaller physical opening, allowing less light into the camera.

Depth of Field

The distance in front of and beyond the focal plane that appears acceptably sharp; larger aperture openings produce a shallower depth of field.

Shutter Speed

The duration for which the camera shutter remains open during exposure; slow speeds introduce motion blur whereas fast speeds freeze movement.

ISO

The measurement of sensitivity of a camera's image sensor; lower numbers require more light but provide finer grain, while higher numbers allow low-light capture with increased digital noise. Forensic standards generally use ISO $200$.

Exposure Triangle

The interrelated triad of camera variables—aperture (f-stop), shutter speed, and ISO—where an adjustment to any single setting requires compensating adjustments to the others.

Polarizing Filter

An optical filter attached to a lens to minimize reflections, diminish glare from non-metallic surfaces, and enhance colour contrast.

ABFO #2 Scale

An L-shaped, right-angle photomacrographic ruler designed to provide standardized measurement and perspective rectification, particularly on human injuries and bite marks.

Locking Cable Release

A mechanical or electronic trigger that locks a camera shutter open for long-duration exposures, commonly used in nighttime or low-light scenes.

Four Corners Approach

A systematic interior photography technique wherein the investigator documents the room from all four corners looking inward to cover all layout perspectives and evidence positions.

Overview Photos

Photographs that show the crime scene exactly as it was first encountered, capturing broad context and layout without moving or reconstructing any items.

Mid-Range Photos

Photographs that establish the position and spatial relationship of a specific item of evidence relative to its immediate surroundings.

Close-Up Photos

Detailed, macro-level photographs taken directly over individual pieces of physical evidence to document unique characteristics and minute details.

Close-Up with Scales

Evidence photographs taken perpendicular to the subject with a suitable measuring device on the exact same plane to document accurate physical dimensions for forensic comparison.

Reflected UV Photography (Bruising)

A specialized technique using ultraviolet wavelengths ($< 400\,\text{nm}$) and camera filters at approximately $30\,\text{cm}$ distance to image deep-tissue bruising not visible under standard white light.

Ninhydrin Prints Photography

The photographic documentation of chemically developed latent fingerprints using a green contrast filter to highlight the purple Ruhemann's purple reaction product against paper.

Infrared (IR) Photography

A photographic method utilizing infrared illumination and filters to detect obscured writings, burned paper text, gunshot residue, and blood on dark surfaces.