ASA Speed: Light sensitivity of film expressed in mathematical values. Equivalent to ISO (International Standards Organization) film speed ranges. The higher the number, the more sensitive the film is to light.

Aberration: A lens flaw that produces degraded sharpness, lowered contrast, distorted shape or other imperfections in photographs.

Ambient Light: Light already existing in an indoor or outdoor scene independent of any light supplied by the photographer.

Aperture: An opening in a lens through which light enters. Aperture size is calibrated in f-numbers. The larger the f-number (ex.f11, f16) the smaller the opening size.

Aperture Priority Automatic Camera: An automatic exposure camera that automatically adjusts the shutter speed to correctly expose the picture once the photographer has set the lens opening.

Automatic Diaphragm: A lens aperture that stays at its widest opening until the moment of exposure, when it closes down to the aperture at which it is set. After the exposure, it returns to the widest setting again.

Automatic Exposure Camera: A camera with a built-in metering system the automatically adjusts the lens opening (aperture), shutter speed, or both for proper exposure.

Automatic Flash: An electronic flash that has a photocell which measures the amount of flash illumination reflected back by the subject. When enough light for a properly exposed picture is reflected to the photocell, it stops the flash from emitting more light.

Auto Focus: As the name implies, a camera or lens that automatically adjusts the focus by a variety of electronic or mechanical means.

Autowinder: A motorized mechanism for advancing the film in a camera and recocking the shutter. Most autowinders have a maximum speed of about two frames per second. Standard feature on most modern autofocusing cameras.

Bulb Setting: A shutter speed setting on adjustable cameras that keeps the shutter open for as long as the shutter is pressed. Used for taking timed exposures with a cable release.(e.g. Astronomical photography)

Bas-Relief: A special-effects darkroom technique that outlines the subject with a dark or light line. Created by sandwiching a high contrast negative or positive slightly out of register with the original image in the enlarger's film carrier.

Bayonet Lens Mount: A method of mounting a lens onto a camera body. The lens is inserted into the camera and given a short turn to lock it into place. Except for a few instances, a bayonet mount camera will not accept bayonet mount lenses made by a different manufacturer. The most common method of lens mounting.

Bellows: An accessory with a flexible pleated material that goes between the camera and lens to extend the lens to film distance for extreme close-up photography. In most cases the photographer will have to increase the exposure to compensate for light reduction.

Bracketing: Taking additional photos of a subject over a range of varying exposures when unsure of the correct exposure.

Bulk Film: Long rolls of 35 mm film packaged in lightproof cans instead of in individual ready to use cassettes. Must be cut into 36 exposure or shorter lengths and loaded into cassettes for use. Used in conjunction with a bulk film loader.

Burning in: Selectively adding more exposure to areas of a print that would otherwise be too light, a specialized darkroom technique.

Cable Release: A flexible cable with a plunger on one end that is attached to a camera's shutter release. When the plunger is pressed, the shutter is tripped. They are now available as multi-function electronic remotes with most of the newer autofocus cameras.

Changing Bag: A light proof black fabric bag that permits film and other light-sensitive materials to be handled in normal room light. Has a double zipper on one end and two armholes with elastic sleeves on the other.

Close-Up Lens: A lens attachment that permits a lens to focus closer than normal. Usually sold in sets of three, with each close-up lens a different strength for focusing at varying distances.

Cold Mount: Means of mounting photos on cardboard with sheets of adhesive that require pressure instead of heat to make a permanent bond.

Colour Analyzer: An electronic instrument for colour printing that compares the colour and density of a negative to that of a reference negative that has been programmed into the analyzer.

Colour Temperature: A comparison of the colour temperature of a given light source, expressed in degrees Kelvin (e.g. daylight is approx. 5000-6000 degrees Kelvin)

Condenser Enlarger: An enlarger using one or more glass condenser lenses between the lamp and film plane to provide a focused and even distribution of light. Contact Paper: A slow speed black and white photo paper used primarily for making contact prints from negatives. Kodak AZO is an example.

Cross Screen Filter: A clear filter etched with a fine grid pattern which produces "starburst" flare patterns around light sources in a scene.

Daylight Film: Colour film that is suitable for use in average daylight or with electronic flash without any filters. (balanced for 4500-6500 degrees Kelvin)

Daylight Tank: A film processing tank that can be used in normal roomlight once the film has been loaded into it in total darkness.

Dedicated Flash: An electronic flash that is designed for specific camera makes and models. When the flash is attached to the camera and turned on, the camera's shutter speed is automatically adjusted to the correct setting. Normally with dedicated flashes other functions have also been automated.

Depth of Field: The distance range from the camera to the nearest and farthest points in a scene that are in sharp focus. Use the aperture to determine the depth of field, the smaller the aperture (f11, f16, etc) the longer the depth of field.

Diazo Film: A monochromatic film that is sensitive to only ultraviolet light and is developed in ammonia fumes. Main photographic use is for making colour title slides from high contrast negatives.

Dichroic Enlarger: An enlarger equipped with dichroic filters for colour printing. Dichroic filter values are adjusted by turning dials normally located on the side or top of the enlarger. Dichroic enlargers may have either a diffusion or condenser lamphouse.

Dichroic Filters: Filters encased in glass for colour printing that are built into an enlarger head. The colour balance of dichroic filters is set by adjusting dials, instead of moving individual filters.

Diffraction Filter: A clear filter on which tiny lines have been etched to create rainbow coloured bursts of light from point light sources in a scene.

Dodging: Reducing the exposure to areas of a print that would otherwise be too dark (specialized darkroom technique).

Dry Mount: A method of mounting photographs onto heavy cardboard by using sheets of heat activated adhesive tissue with a dry mount press or household iron.

Easel: A device that holds a sheet of photo paper flat and properly positioned under an enlarger, or a self standing photo mount or folder.

Emulsion: A light sensitive coating on photographic film and paper. An emulsion is made up of silver halides and gelatin.

Enlarging Paper: Photographic printing paper for making enlargements from negatives. Has faster emulsion speed than (more light sensitive) than contact paper.

Extension Tubes: Hollow metal tubes that mount between the camera and the lens to permit closer than normal focusing. The longer the extension the closer the lens will focus; a lower priced substitute for a bellows unit.

Ferrotype: A method of producing a high gloss finish on fiber-based prints by squeegeeing them onto shiny ferrotype plates while damp and then allowing them to dry. A specialized darkroom technique.

Fiber-Base Paper: Photographic paper consisting of light sensitive emulsion coated on a durable paper base. See also "silver prints."

Filter Size: The diameter of the filter retaining threads on the front of a lens in millimeters. Common sizes include 49, 52, 55, 58, 62, 67mm.

Fisheye Conversion Lens: A lens attachment that can be used with most wide-angle, normal and telephoto lenses to take extreme wide-angle pictures. Available in most filter sizes, fisheye conversion lenses are a less expensive alternative to a real fisheye lens.

Fisheye Lens: An extreme wide angle lens. Most fisheye lenses cover a 180 degree angle of view; popular focal lengths include 6, 8 and 14mm. The 6mm and 8mm lenses produce a circular image on the film. (not full frame)

Flash Meter: An instrument for measuring the amount of light produced by a flash unit. (normally expressed in f numbers)

Flash Synchronization: The adjustment and timing of camera and flash so that the flash fires when the camera shutter is open. Most 35mm SLR cameras synchronize with electronic flash at shutter speeds of 1/60th or slower. (newer models will even synchronize at speeds up to 1/250th)

Graded Paper: Black and white photo paper that is manufactured on specific contrast grades. Normally expressed as a scale from 1-5, with 5 being the highest contrast.

Guide Number: A rating of a flash unit's power. Can be divided as the proper exposure setting for a photo taken with the flash ten feet from the subject, multiplied by ten. For example, a flash with a guide number of 56 will produce enough light for an exposure of f5.6 at ten feet

Hot Shoe: A standardized method of mounting an electronic flash on a camera. The hot shoe fittings on both the camera and flash have an electronic contact in the center that fires the flash when the shutter is pressed. Usually located on the center top of the camera, however most newer cameras have an electronic flash already built in.

Infrared Film: A black and white or colour film that is sensitive to infrared radiation, which is invisible to the human eye. During focusing the photographer must refocus after set up as infrared film is on a different plane than what the human eye sees.

Internegative: A copy negative made from a slide.

Keystoning: The distortion of a projected slide or movie caused by the projector lens axis not being at a 90 degree angle to the screen. The image will appear wider at one edge than on the opposite and the image will not be uniformly sharp.

Kodalith: A high contrast black and white film made by Kodak, used also as a special effect film in the darkroom.(ultra high contrast images)

Leica Thread Mount: A screw type lens mounting style with 39mm diameter threads. Most enlarging lenses also have a 39mm thread mount.

Lens Hood: A short conical shaped tube that attaches to the front of a lens to shield it from extraneous light. Helps prevent lens flare, ghost images and loss of contrast. An inexpensive must have accessory for your camera system.

Light Meter: A device that measures the intensity of light. Can be either built into a camera or as a separate hand held instrument.

Macro Adapter Lens: A lens attachment that permits a lens to focus much closer than normal.

Macro lens: A primary lens that can be focused from a very short distance out to infinity. May be a fixed focal length lens or a zoom. However most high magnification Macro lenses (lifesize or higher) are fixed.

Mirror Lens: A type of long telephoto lens that uses several mirror optic surfaces to "fold" the light path, resulting in a very powerful telephoto lens that is relatively small.

Modeling Light: A relatively weak incandescent light bulb mounted in an electronic flash head next to the flash tube. The continuous illumination from the modeling light makes it possible to preview the lighting effect that will be produced by the flash.

Motor Drive: A motorized mechanism for advancing the film in a camera and recocking the shutter. Motor driven cameras usually have a maximum speed of between 2-6 frames per second. However new advances in shutter technology enable some cameras to shoot up to 10 or more frames per second.

Mount Board: White, gray, black or coloured cardboard onto which prints are mounted for display. Also called mat board.

Multicoating: The application of several coats of materials to the surface of lens elements to improve light transmission, contrast and the reduction of lens flare.

Negative: A photographic image on which tones and colours appear the opposite of the original scene.

Nicad Batteries: A type of dry cell battery that can be recharged an almost indefinite amount of times. Improper handling of nicads will result in battery "memory", which will impede full charging. Should always be fully exhausted before a recharge.

Normal lens: A lens with a focal length of approximately the diagonal measurement of the film image area. A 50mm lens is considered the normal lens for 35mm photography. Normal lenses view the subject like unaided human eyes, neither reducing or enlarging the subject size.

PC/PC Extension Cord: A cord that goes between a camera and a flash unit's shutter cord to permit the flash to be positioned farther from the camera. Available in different lengths, also as dedicated, non dedicated and TTL extensions.

Parallax: The difference between the field of view seen through a camera's viewfinder and the image recorded on film by the taking lens of a twin lens reflex camera. Parallax is due to the distance between the viewfinder and taking lenses on rangefinder and twin lens reflex cameras and is most evident at close subject distances. SLR cameras don't have the problem because the subject is viewed through the taking lens.

Perspective Control Lens: A wide angle lens design featuring optics that can be shifted to correct for converging vertical lines, inherent in wide angle lenses. Available mainly in 28 and 35mm focal lengths, these lenses are used normally for architectural photography.

Photograms: Photographs made without a camera by placing opaque objects on a sheet of photographic paper, exposing to light and processing. Photograms have dark backgrounds and white silhouettes of the opaque objects.

Polarizing Filter: A common filter that removes reflections from water, glass and other surfaces, it also increases colour saturation.

Posterization: A special effects printing technique that separates normal tones into distinct tone ranges by the use of high contrast films. A specialized darkroom technique.

Programmed Auto Exposure Camera: An automatic exposure camera that automatically selects both the shutter and the aperture to properly expose the picture. (point and shoot) Most modern 35mm SLRs have some sort of programmed automation.

Push Processing: The technique of over developing film to compensate for intentional underexposure by the photographer. Commonly used to gain faster shutter speeds or greater depth of field than normally exposed and processed film will permit.

Rangefinder Camera: A camera with a rangefinder focusing system, which provides a double image of the subject in a small central area of the viewfinder. When in focus the double image appears as a single image.

Reflex: A camera design using mirrors or prisms to reflect the scene onto a ground glass focusing screen.

Reproduction Ratio: The ratio of the actual size of an object to it's reproduced size on film. A 1:1 ratio means that the object is represented as life size on the film, a ratio of 1:2 means that the object is half life size.

Resin Coated Paper: Photographic paper that has thin coating of plastic resin on the backside of the paper and in between the emulsion and paper support. RC paper absorbs less of the processing chemicals, requires a shorter wash and dries faster than fibre based paper.

Reticulation: A special effects darkroom technique that creates an overall pattern in film by subjecting it to extreme changes in the temperature of the processing solutions.

Reversal Film: A type of film that produces positive images by being reversed from negative images during processing. Colour slide films are reversal films.

Reverse Adapter: An adapter ring that permits a normal lens to be mounted onto a camera backwards for improved results when taking extreme close-up photos.

SLR: Single Lens Reflex camera, a type of camera design that permits the photographer to view, expose and focus on the subject through the taking lens instead of a separate viewfinder window.

Sabatier Effect: A special effect darkroom technique that produces both negative and positive images on the same film or paper by re-exposure to light partway through development.

Shutter: A mechanism containing curtains, blades or plates that control the length of time film is exposed to light.

Shutter Cord: A cord that couples a flash unit to a camera. Provides for external synchronization between the shutter and the flash.

Shutter Priority Automatic Camera: An automatic exposure camera that automatically adjusts the lens opening (aperture) to a shutter speed that has been pre-set by the photographer.

Skylight Filter: A very pale pink filter used with colour film to reduce excess blue found in outdoor scenes. Commonly left on the lens all the time, acting as a lens protector.

Slave Sensor: A device with a photocell that triggers a flash unit when it senses light from another flash unit. The light from both flash units with be synchronized with the camera.

Solarization: A special effects darkroom technique that reverses the image on the film by extreme overexposure. Photos made by the Sabatier effect are often referred to as having been solarized.

Split Field Lens: A semi circular close up lens in rotating mount. Attaches to the front of a lens and enables it to render near and distant objects in focus at the same time.

Step Down Ring: A filter size adapter ring that permits a lens to use filters smaller than the lens filter size.

Step Up Ring: A filter size adapter ring that permits a lens to use filters larger than the lens filter size.

T-Mount: An interchangeable lens mounting system for slide duplicators, microscope adapters and telescope attachments, lenses without automatic diaphragms and other optical accessories. A T-mount is a metal ring with female 42mm threads on one side to screw onto the lens attachment and a male camera mount on the other side.

Tele-Converter: A lens accessory that mounts between a camera body and normal, telephoto or telephoto zoom lenses to double (or triple) the effective focal length. A 2X tele-converter will make a 80-200 zoom lens seem like a 160-400 zoom. A 2X converter will also add 2 stops to the maximum aperture. (ex. an 80-200 f4 zoom will become a 160-400 f8 zoom)

Telephoto Lens: Lenses whose focal lengths are longer than 50mm (in 35mm photography). Telephoto lenses enlarge the subject size.

Texture Screens: A clear material onto which a texture has been embossed or imprinted. A texture screen is placed on the photo printing paper or sandwiched with the negative to add the appearance of texture to a print. A specialized darkroom technique.

Thyristor: A type of circuitry used in automatic flash units which returns unused energy to the capacitor after each shot. This design reduces recycling and power consumption substantially.

TTL Flash: Through the lens flash metering. Sensors located in either the prism, the mirror or on the film plane which record the amount of electronic flash coming into the camera at the time of exposure. These sensors will automatically adjust the output of the flash. A very accurate method of flash metering.

Transparency: A positive photographic image viewed or projected by transmitted light. Colour slides are transparencies.

UV Haze Filter: A visually clear filter that removes bluish haze caused by ultraviolet light. Commonly left on the lens all the time to serve as protection.

Umbrella: A lighting accessory consisting of reflective fabric stretched over a metal frame. Used to reflect soft, even light onto a subject.

Universal Screw Mount: A style of lens mounting once used by Pentax, Praktica and other camera makers. The universal screw mount has 42mm diameter threads on the lens mount.

Variable Contrast Paper: Black and White photo paper whose contrast is controlled by using filters. Kodak Polycontrast and Ilford Multigrade are two examples of Multi-Contrast papers. The filters are available in grades from 1-5 (5 being high contrast).

Variable Focal Length Lens: A type of zoom lens that requires refocusing as it is zoomed.

View Camera: A style of camera consisting of a bellows connecting a lens support and film holder, mounted on a rail or pair of rails. View cameras offer the lens and film planes a great deal of unrestricted physical movement for controlling depth of field and perspective.

Vignette: The darkening of the corners of a photograph. Commonly caused by lens hoods, filters and other lens attachments that reduce a lens' angle of view. May be done intentionally by the use of special filters or masks in front of the lens or by using special techniques during printing.

Wide Angle Lens: A lens with a focal length shorter that the normal lens. In 35mm photography, lenses shorter than 50mm are considered wide angle lenses.

Zone Focusing: A type of focusing system that has two or more focus settings for varying subject distance ranges, rather than a continuously adjustable focusing ring.

Zoom Lens: A lens in which the focal length can be adjusted over a wide range. One touch zoom lenses allow the photographer to adjust the focal length by pushing or pulling the focusing ring. Other zoom lenses have a separate zoom control ring that is turned to adjust the focal length. Rapidly replacing the 50mm lens as a standard lens, most standard zoom lenses have a focal length of from 35-70mm.