Forensic Photography Vocabulary Flashcards

Comprehensive vocabulary flashcards covering key terms, principles, formulas, optics, equipment, and methodologies from forensic photography lecture notes.

Forensic Photography

The art or science of photographically documenting a crime scene and evidence for laboratory examination and analysis for purposes of court trial.

Phos / Photos

Greek word meaning light.

Grapho / Graphia

Greek word meaning writing or to draw.

Alphonse Bertillon

Recognized as the Father of mugshot photography who first used photography in personal identification.

Crime Scene Photography

Involves documenting the scene of a crime, including taking pictures of victims (scars, wounds, birthmarks) and physical evidence.

Police Photography

The application of the principles of photography in relation to police work and the administration of justice.

Photograph

The mechanical and chemical result of photography; an image that is exclusively the product of photographic processes.

Picture

A generic term derived from the Latin pictura or pictus referring to all kinds of formed images made by painting, drawing, or photography.

Negative

A material showing a latent photographic image on transparent material used for printing positive photographs via chemical processing.

General View

An overall photo view of the crime scene showing its general direction and location.

Medium View

A photographic view of the crime scene taken by dividing the scene into sections to best show the nature of the crime.

Close-up View

An individual photograph of evidence at the crime scene designed to show detailed features.

Extreme Close-up View

Laboratory photography utilizing high magnification such as photomacrography and photomicrography to capture minute details.

Photomicrography

Taking a magnified photograph of a small object by attaching a camera to the ocular of a compound microscope.

Photomacrography

Taking a magnified photograph of a small object by attaching an extended tube lens (macro lens) to the camera.

Microphotography

The process of reducing a scenario or document into a small strip of film.

Telephotography

The process of taking photographs of far objects with the aid of a long focus or telephoto lens.

Velocity of Travel

A quality of light wave motion referring to light speed, approximately $186,000\,\text{miles/sec}$ in air or $300,000\,\text{km/sec}$ in open space.

Frequency

The number of cycles of light that pass a given point in one second.

Millimicron

A unit of light wavelength equivalent to one-millionth part of a millimeter ($10^{-6}\,\text{mm}$).

Angstrom

A unit of light wavelength equivalent to ten-millionth part of a millimeter ($10^{-7}\,\text{mm}$).

Development

The chemical process by which an invisible latent image in an emulsion is made visible.

Stop-Bath

A chemical bath that halts developer action at the appropriate moment and prevents cross-contamination between developer and fixer.

Fixation

The chemical process that makes a developed image permanent by removing unaffected silver salts prior to washing.

Wave Theory

Light theory proposed by Huygens comparing light propagation to the up-and-down wave motion observed in water.

Corpuscular Theory

Light theory proposed by Newton stating that light produces effects through the motion of tiny particles like electrons.

Visible Spectrum

The small portion of the electromagnetic spectrum detectable by human sight, ranging from $400\,\text{m}\mu$ to $700\,\text{m}\mu$.

Primary Colors of Light

Red ($700\,\text{m}\mu$), Green ($550\,\text{m}\mu$), and Blue ($450\,\text{m}\mu$).

Complementary Colors of Light

Magenta ($400\,\text{m}\mu$), Cyan ($500\,\text{m}\mu$), and Yellow ($590\,\text{m}\mu$).

Specular Reflection

Regular reflection occurring when light hits a flat, smooth, and shiny surface.

Diffuse Reflection

Irregular reflection occurring when light hits a rough or uneven glossy object.

Refraction

The bending of light rays as they pass from one transparent medium to another.

Diffraction

The bending of light when it encounters a sharp edge of an opaque object.

Rectilinear Propagation

The property of light that describes its natural behavior of traveling in straight lines.

Polarization

The process by which the vibrations of light rays are confined to a definite plane.

Luminescence

The conversion of absorbed light energy by an object into light of a different wavelength.

Fluorescence

The ability of an object to absorb energy at one wavelength and instantly radiate it at another wavelength.

Phosphorescence

The emission of converted light from an object that continues after the initial excitation light source is removed.

Transparent Object

A medium that allows sufficient visible light to pass through so objects behind it are clearly visible.

Translucent Object

A medium that allows light to pass but diffuses it so objects on the other side are not clearly distinguished.

Opaque Object

A material that blocks or diffuses light so greatly that objects on the other side cannot be seen.

X-Ray

Photographic rays discovered by Wilhelm Roentgen with wavelengths from $0.1\,\text{m}\mu$ to $30\,\text{m}\mu$, working on shadow photography principles.

Ultraviolet Ray

Invisible light with wavelengths from $30\,\text{nm}$ to $400\,\text{nm}$ (black light), used to photograph altered documents, fingerprints, and body fluids.

Infrared Ray

Photographic rays with wavelengths from $700\,\text{m}\mu$ to $1000\,\text{m}\mu$ (heat rays), used for charred documents, obliterated writing, and surveillance.

Clandestine Photography

Commonly referred to as surveillance photography; the covert photographing of a person, object, activity, or location.

Photoflood Lamp

A continuous radiation reflectorized spotlight that focuses light onto a subject, commonly rated at $500\,\text{W}$.

Electronic Flash

An artificial light source that produces illumination via an instantaneous electrical discharge between electrodes in a gas-filled bulb.

Sensitized Material

Film or photographic paper composed of an emulsion containing silver halides suspended in gelatin on a support base.

Silver Halides

Compounds of silver with fluorine, chlorine, bromine, or iodine in film emulsion that react upon light exposure.

Emulsion

The light-sensitive gelatin layer of film or paper containing suspended silver grains.

Anti-Halation Backing

A specialized backing layer designed to absorb light and prevent light reflection or halation in film.

Orthochromatic Film

Film sensitive to UV light, blue, and green colors, but insensitive to red light.

Panchromatic Film

Film sensitive to UV light and all visible colors of the spectrum.

ASA

American Standards Association film rating system expressed in arithmetic values where higher numbers mean higher sensitivity.

DIN

Deutsche Industrie Normen film speed rating system expressed in logarithmic values.

ISO

International Organization for Standardization film rating system combining ASA and DIN values.

Silver Chloride Paper

Photographic paper used for contact printing with low light sensitivity that yields blue-black tones.

Silver Bromide Paper

Photographic paper used for projection printing and enlarging that yields black tones.

Camera

A light-tight box equipped with a light-gathering mechanism to prevent unwanted light from reaching sensitized material.

Shutter

A camera mechanism that regulates the length of time light is allowed to strike the film or sensor.

Focal Plane Shutter

A shutter located near the focal plane consisting of a cloth curtain that opens across the film frame.

Central Shutter

A shutter located near the lens leaves made of metal that opens outward from the center.

Pentaprism

A five-sided optical glass prism in SLR cameras that reflects light to present an upright and unreversed image in the viewfinder.

Exposure

The product of light intensity and time acting on photographic material: $\text{Exposure} = \text{Intensity} \times \text{Time}$.

Overexposure

The result of allowing excessive light to reach the sensitized material, producing a pale print.

Underexposure

The result of allowing insufficient light to reach the sensitized material, producing a dark print.

Aperture

The adjustable opening or pupil in a camera lens that controls light intensity passing to the film.

F-Number

A numerical ratio representing aperture size; larger f-numbers denote smaller lens openings.

Depth of Field

The distance measured from the nearest to the farthest object appearing in sharp focus at a specific distance setting.

Hyperfocal Distance

The nearest focus distance at a given aperture that provides maximum depth of field reaching infinity.

Single Lens Reflex Camera

A camera design utilizing a mirror and pentaprism mechanism so the photographer views directly through the main photographic lens.

Convex Lens

A positive converging lens thicker at the center that bends light rays together to form a real inverted image.

Concave Lens

A negative diverging lens thinner at the center that spreads light rays apart to form a virtual image.

Normal Lens

A camera lens with a focal length of $50\,\text{mm}$ that approximates normal human vision.

Wide-Angle Lens

A camera lens with a focal length less than $50\,\text{mm}$ ($\le 35\,\text{mm}$) offering a broader field of view.

Telephoto Lens

A camera lens with a focal length greater than $50\,\text{mm}$ providing a narrow field of view and magnifying distant subjects.

Spherical Aberration

A lens defect where light rays passing through outer edges focus closer than central rays, causing outer blur.

Chromatic Aberration

A lens defect caused by failure to focus light of varying wavelengths to the same focal point, creating color fringes.

Astigmatism

A lens defect where horizontal and vertical lines in an object cannot be brought into focus simultaneously.

Barrel Distortion

A lens defect causing straight outer image lines to bow outward, giving a spherized appearance.

Pincushion Distortion

A lens defect causing straight outer image lines to curve inward toward the lens axis.

Polarizing Filter

An optical filter used to eliminate or reduce glaring reflections on glossy or highly reflective non-metallic surfaces.

Dodging

The process during enlarging of holding back light from specific regions of paper to lighten those areas.

Burning-In

The process during enlarging of applying additional exposure to specific print regions to darken them.

Cropping

The process of eliminating unwanted outer portions of an image during printing or enlarging.

Overlapping Method

A crime scene photography technique taking a series of circular or clockwise photographs that slightly overlap.

Progressive Method

A crime scene photography technique starting at a fixed point and taking photos progressively closer to specific pieces of evidence.