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Digital Photography
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The use of electronic means to capture light and save an image on a microchip
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terms list
Digital Photography
The use of electronic means to capture light and save an image on a microchip
Film Speed
The rate at which the silver halide grains of a given film react to light
Film
Light-Reactive silver halide grains which come in several varieties.
Print Film
Produces a negative image that is developed to produce a positive image
Slide Film
Produces positive image on transparent slides used for presentation
Infrared Film
Produces image when exposed to infrared light.
Film Size 135
35mm, Image area 24x36mm, Roll Film
Film Size 120
60mm wide, 45 or 60mm in length, only median format film, Roll Film
Sheet Film
Large prints can be made on sheet film instead of rolled film. Commonly measures 4 x 5 inches, Sheet Film
Measurement of Film speed
2 different scales to measure film speed; The International Standardization Otganization (ISO) and The German Institution for Standardization (DIN)
ISO
The International Standardization Organization. Arithmetic scale; 200 ISO speed film simply is twice the speed of 100 ISO speed film
DIN
The German Institution for Standardization. Logarithmic scale; A three-unit increase equals twice the speed. DIN 28 film is twice the speed of DIN 25 film
Polaroid Film
Produces/Prints an instant photograph
Infrared Film use
Used in questioned-document exams, locating gravesites in aerial photography. visualizing gunshot residue on dark fabrics, viewing underlying patterns in bite and bruise marks. Film should not be stored for long periods of time
Polaroid Film use
Serves as quick record of evidence that might not be available for a second try if the pictures don't turn out right. Examples of this are impressions in soil or snow and fingerprints developed at the crime scene
Digital Image Recording
A digital photography is made when a light-sensitive microchip inside the camera is exposed to light coming from an object or scene.
CCD
Charged Coupled Device
CMOS
Complementary Metal Oxide Semi-Conductor
Megapixel
The number of pixels on a digital camera. A unit of graphic resolution. One million pixels used to describe a digital camera in terms of sensor resolution (i.e., four megapixels equals four million pixels)
SLR
Single Lens Reflex camera
DSLR
Digital Single Lens Reflex camera
Lens
The mechanism that bends light to focus an image on the film or digital microchip
Normal Lens
50 - 55 mm focal length, used for most photography
Telephoto Lens
100 mm focal length or greater, used for magnification, 2 x magnification compared to the normal lens
Wide-Angle Lens
35 mm focal length and less than 50 mm, useful in photographing wide objects such as the facade of a building
Macro Lens
focal length less then 50 mm with a 1:1 or 1;2 magnification ratio. Close up photography such as fiber or tool mark evidence
Multipurpose Lens
28 - 80 mm focal length, commonly called a zoom lens can also be used for crime-scene photography. This type of lense allows the photographer to take normal, wide-angle and telephoto photographs without changing lenses
Aperture
The size of the diaphragm opening through which light enters the camera. Adjustment of the aperture is by setting the f-number. The lower the f-number, the more light allowed in
F-Stop
Standard F-Number setting that control the aperture diameter to determine the amount of light transmitted to the lens
Shutter Speed
Controls the length of time that the film or microchip is exposed to light. This is measured in fractions of a second by factors of 1/2 (1/2, 1/4, 1/8 etc.)
F- Number
The ratio of the focal length of a lens or lens system to the effective diameter of its aperture. Also called f-stop. Lowest f-number 1.0 equals f-stop 0. Each f-stop represents a twofold difference in the amount of light entering the camera
Depth of Field (Camera)
The distance between the nearest and furthest objects in focus as seen by a camera lens, which varies with the focal length of the lens, its f-stop setting, and wavelength of light
Color Temperature (Camera)
The measure of the "degree of whiteness" (different hue) of a light source as compared to a hypothetical source of perfect white light. "hot" light source has a bluer hue, whereas a "cold" light source has a red-orange hue
Illumination
Refers to the light falling on the object in a photograph
Flash
Artificial illumination in photography
Electronic Strobe Flash
Most commonly used source of artificial illumination, this type is usually mounted on the top or front of the camera
Flash Unit
An electronic flash that is not mounted to the camera. It is either separately operated or connected to the camera by a cord
Filters (Camera)
Enhances specific elements of a picture or show elements of the picture not usually visible. Filters allow only a specific wavelengths (colors) of light to reach the film
Barrier and Bypass Filter
The two most common types of filters
Barrier Filter
Blocking ONE specific wavelength (color) of light reaching the film or microchip, making areas of that color appear lighter in the photgraph
Bypass Filter
Allowing only a small range of wavelengths of light to reach the film or microchip and blocks all others. Ultrviolet photography uses a bypass filter that allows only ultrviolet light to reach black- and white film
Red Filter
Will darken blue/green areas
Orange/Yellow Filter
Will darken blue/violet areas
Polarizer Filter
Eliminates refelction from windows and water and eliminates glare
Tripod
A three-legged stand or support for a camera or telescope. Photographs taken at a shutter speed less than 60 (1/60 second) must be taken from a tripod.
Photography Log
The form on which the investigator records the details of each photograph taken at the crime scene
Overview Photographs
First picture the photographer takes. It should include the entire scene surrounding area, include points of exit and entry. The Photograph should be taken from the outside borders of the scene and from various angles
Medium-Range Photographs
Showing the center of the scene as well as the layout of smaller significant areas of the crime scene. They should be taken with evidence markers in place to show the spatial relationship between and among pieces of evidence in greater detail
Visual Tag
An object that is included in multiple overview photos to help visually piece the scene together
Close-Up Photographs
Showing greater details of individual objects or evidence and taken last on the scene. The picture must be taken at a 90-degree angle to the object, with and without evidence markers and scales.
The Four minimum photographs required
Overview, Medium-Range, Close-Up, and Close-Up with scale
Special Photography
Indoor scenes, Outdoor scenes, Arson photography, Sexual assault victim photography, Impression photography, Bloodstain photography
CAD
Computer-Aided Drafting. The process of creating scaled drawing using specially designed computer software
Notes, Photographs, and Scetches
The three methods for recording the crime scene
Latent Fingerprint Photography
Close-up photographs of hidden fingerprints that should show the ridge details of the fingerprints for identification
Lossless Compression
The method to compress and save a digital file without disgarding digital data
Rough Sketch
The first sketch created at the crime scene with care for accuracy in depicting dimensions and locations but no concern for aesthetic appearance
Finished Sketch
The perfected final sketch that is constructed with care and concern for aesthetic appearance and is drwan to scale
Notes
Before evidence is collected, it must be fully described in the investigator's ____________.
Painting with Light
A technique that may be used to illuminate long distances in total darkness in night-photography
Standard Operating Procedure
Ensuring that digital images be admissible and to avoid the possibility of enhancement or doctoring of crime-scene photographs
Rectangular, Triangulation, baseline or polar coordinates
When creating a rough sketch, measurments should be taken from the fixed points to pieces of evidence by using one of the four methods
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