Glossary Of Photographic Terms

Glossary of common terms in Photography

Student Photograph

Student Photograph

Here is an ever expanding page of photographic terms used in the industry, click the appropriate letter underneath to find the definition you are looking up.



  • Aberration: Defect in a lens resulting in less than optimum sharpness over part of the image plane. See Chromatic Aberration, Spherical Aberration.
  • Accessory shoe: Fitting on a camera to allow devices such as flashguns to be clipped on. See Hot Shoe.
  • Accelerator: Chemical ingredient of developer to speed up the otherwise slow activity of developing agents. Normally an alkali such as sodium carbonate, borax or (high contrast developers) sodium hydroxide. Also known as ‘activator’ or ‘alkali’ component.
  • Achromatic Lens: system corrected to eliminate the effects of chromatic aberration.
  • Acid: Chemical substances with pH below 7. Harmful to skin and eyes. Because acid neutralizes
    an alkali, acidic solutions are often used to halt development as in stop bath or fixer.
  • Adaptor ring: Narrow threaded ring which fits the front rim of a lens to allow use of filters or accessories of a different (‘step-up’ or ‘step-down’) diameter.
  • ADC: Analogue Digital Converter. The piece of electronics which transforms the signal from a digital camera’s sensor into a stream of digital information.
  • AE Automatic exposure: The camera adjusts the shutter and/or aperture settings itself, based on readings from a built-in light meter.
  • AE lock (AE-L): Camera control which allows the user to hold the exposure settings made by an auto exposure program before re-composing the picture.
  • Aerial perspective: Sometimes referred to as Atmospheric perspective. Sense of depth conveyed by atmospheric haze, i.e. changes of tone with distance. Distant hills appear paler and possibly cooler in tone than similar features nearer the camera.
  • AF Autofocus: The camera adjusts the focus point of the lens itself using sensors to determine maximum sharpness.
  • AF lock (AF-L): Camera control which allows the user to hold the focus setting made by an auto-focusing lens before re-composing the picture.
  • Aliasing: A rough edge effect (‘jaggies’) seen most clearly on diagonal or curved lines in an electronic image. Created by low pixel resolution. This staircase appearance is due to the large square pixels present.
  • Alkali: Chemical substances with pH above 7. Harmful to skin and eyes. Solution feels slippery to the touch, can neutralize acid. See also Accelerator.
  • Ambient light: General term covering existing subject lighting, i.e. not specially provided by the photographer.
  • Analogue: Continuously variable. A traditional negative is one example of analogue data having a continuous range of tones in colour or black to white. Often used to mean ‘non- digital’.
  • Angle of view: Angle, formed at the lens, between lines from the extreme limits of a (distant) scene just imaged within the diagonal of the picture format. Varies with focal length and format size.
  • Anhydrous (anhyd): Dehydrated form of a chemical. More concentrated than the same substance in crystalline form.
  • ANSI: American National Standards Institute. Present title of organization once called American Standards Association. See ASA.
  • Anti-halation Light-absorbing dye present in film to prevent reflection or spread of light within the film base itself giving ‘haloes’ around bright highlights. Dissolved during processing.
  • Aperture: Circular or hexagonal opening within the lens used to control image brightness and depth of field. Usually variable in diameter and controlled by a diaphragm calibrated in f-numbers.
  • Aperture (Apple Aperture): Software application from Apple Inc. used for organising and manipulating digital images.
  • Aperture preview: SLR camera control to close the lens diaphragm to the actual setting used when exposing. For previewing depth of field effects in the image.
    Aperture-Priority See Av.
  • APS (Advanced Photographic System): System of easy-load cameras and film cartridges about 30 percent smaller than 35 mm, planned and introduced (1996) by a consortium of manufacturers: Canon, Fuji, Kodak, Minolta and Nikon. All but defunct now but see APS-C and APS-H.
  • APS (Active Pixel Sensor): A type of digital image sensor (see CMOS) where each pixel sensor contains its own amplifier. APS sensors consume less power and are faster than a CSS sensor and are widely used in mobile phone cameras.
  • APS-C/APS-H: Originally terms describing Advanced Photographic System negative formats (see APS). These are now often used to describe the size of digital image sensors. They approximate to the APS dimensions of 25.1 × 16.7 mm; (3:2 aspect ratio) for APS-C (‘Classic’) and 30.2 × 16.7 mm (16:9 aspect ratio) for APS-H (‘High definition’).
  • Archival processing: Procedures during processing aiming for the most stable image possible to ensure long life.
  • Archival inks: Inks made for digital printers that have long-lasting permanence.
  • Array: A single row of charge-coupled devices (CCDs), as used in flatbed scanners, etc., to
    respond to light and convert it to digital information.
  • Artificial light: General term for any man-made light source. Artificial-light film, however, normally refers to tungsten illumination of 3200 K.
  • ASA: American Standards Association, responsible for ASA system of speed rating. Doubling the ASA number denotes twice the light sensitivity. Now replaced by ISO.
  • Aspect ratio: The ratio of the width to the height of an image. 35 mm format has an aspect ratio of 3:2, computer monitor and TV screens 4:3.
  • Asynchronous Digital Subscriber Line (ADSL): High-speed Internet connection that runs over an exiting phoneline. Consumer ADSL systems are commonly known as ‘Broadband’.
  • Autofocus: System by which the lens automatically focuses the image (for a chosen area of subject). See AF.
  • Av: Aperture value. Auto-exposure camera metering mode. You choose the aperture, and the camera’s meter sets an appropriate shutter speed. (Also known as aperture priority system.)



  • B: setting See Bulb.
  • Bag bellows: Short, baggy form of bellows used on view cameras when working with a wide-
    angle lens. Allows camera movements otherwise restricted by standard lens bellows.
  • Ball and socket: Swivelling ball joint between camera and tripod, monopod, etc. Typically allows setting at any angle with a single locking control.
  • Barndoors: Set of folding metal flaps fitted around the front of a spotlight. Controls light spill, or limits beam.
  • Baryta papers: See Fibre-based paper.
  • Batch number Data printed on film and paper packaging at manufacture. Small production variations occur in speed, contrast and colour but materials from the same batch will be consistent.
  • Baseboard camera: Also known as a Field camera. View camera with fold-open baseboard, which supports lens and bellows.
  • Bellows: Concertina shaped light-tight sleeve used on some cameras and enlargers between lens and film to allow extensive focus adjustment.
  • Between-lens shutter: Bladed (or ‘leaf’) shutter positioned between elements of a lens, close to the aperture.
  • Bit (b): A binary digit. Basic digital quantity representing either 1 or 0. The smallest unit of computer information.
  • Bit depth: The number of bits per pixel. Can vary from 1 bit per pixel within a black and white line image, to 32 or 36 bit depth for a colour image (composed of cyan, magenta, yellow and black, each 8 bits per pixel). The greater the bit depth, the better the tonal gradation and colour quality of the digital image.
  • Bitmap: An image made up of pixels.
  • Bleacher: Chemical able to erase or reduce image density.
  • Blog: A regularly updated (normally diary style) website, either with new images or text – or both.
  • Blonde: A tungsten lamp rated at 2 kilowatts (2000 W). Usually yellow-bodied, hence the name.
  • Blooming: (1) In digital photography refers to haloes or streaks recorded around images of bright light sources or other intense highlights.
  • Blooming: (2) On lenses refers to fungal growths on the glass surfaces due to storage in damp conditions. The fungus produces an acid which can etch the glass, leading to degraded image contrast and sharpness.
  • Blue-sensitive: Emulsion sensitive to the blue and UV regions only of the visible spectrum. Blu-Ray Recording medium physically the same size as a CD or DVD but capable of storing more data – up to 50 GB.
  • Bokeh: A descriptive term for the way out of focus points are rendered. From a Japanese word meaning fuzziness or dizziness.
  • Buffer memory: A built-in memory where the camera can temporarily save images before saving them to the memory card. A buffer allows you to shoot a burst of several shots without having to wait until the images have been written to disk.
  • Bracket In exposure, to take several versions of a shot giving different levels of exposure, usually either side of the metered value.
  • Brief: See Bulb.
  • Brightness: range See Subject brightness range.
  • Broadband: See ADSL (Asynchronous Digital Subscriber Line).
  • Bromide paper: Printing paper with predominantly silver-bromide emulsion.
  • Browser: Software which permits your computer to transfer information and display multimedia sites on the Internet, e.g. Firefox, Safari, Opera, Internet Explorer.
  • Buffer: Chemical substance(s) used to help maintain the pH (acidity or basicity), and therefore the activity, of a solution such as developer or fixer.
  • Bulb: Also ‘brief’. The B setting on a shutter – keeps the shutter open for as long as the release remains pressed.
  • Bulk film: Film sold in long lengths, usually in cans either for reloading into cassettes or for specialist camera backs.
  • Burning-in: See Printing-in.
  • Byte (B): A (small) measurement of the memory or storage space in a computer. One byte equals 8 bits. One kilobyte represents 1024 bytes. See also megabyte, gigabyte and terabyte.



  • C-41 process: Processing procedure used for the vast majority of colour (and monochrome chromogenic) negative films. Originally developed by Kodak but used by all major manufacturers.
  • Cable release: Remote shutter control via flexible cable or electric cord which attaches to the camera. Allows the shutter to be fired (or held open on ‘B’) without camera shake.
  • Cadmium (di)sulphide: See CdS.
  • Capacitor: Unit for storing and subsequently releasing a pulse of electricity.
  • Callier effect: A contrast effect caused by the scattering of light through a condenser enlarger. The denser negative highlights scatter more light than the clear shadows, resulting in abnormally high contrast and a lack of highlight detail.
  • Cassette: Light-proof metal or plastic film container with light-tight entry slot. Permits camera loading in normal lighting.
  • Cast: Overall bias towards one colour.
  • CCD: Charge-coupled device. Electronic light-sensitive surface, e.g. modern substitute for film in digital cameras. In simpler form used in AF systems to detect image sharpness.
  • CC filter: Colour Compensating filter used to correct colour bias mainly when printing. Filters are produced in primary and secondary colours plus ND in a range of densities.
  • CD-R: Compact disc, recordable. A CD to which digital data can be written once only, but read many times. Cannot be erased. Typical capacity is 700 MB.
  • CD-ROM: Compact disc with read-only memory. Non-re-writable disc used to provide software programs, etc.
  • CD-RW: Compact disc, read/write. A CD to which data can be read and written many times. (Old data is erased by laser beam.)
  • CdS: Cadmium disulphide; used in the battery powered light sensor cell, commonly utilized in hand-held exposure metres.
  • Changing bag: A bag of opaque fabric with light-proof arm holes, allowing film holders, cameras or tanks to be loaded or unloaded in normal lighting conditions.
  • Characteristic curve: Graph relating exposure to resulting image density, under given development conditions. See p. 276 and Figure 11.19. Also known as an H–D curve.
  • Chemical processing: All developing and printing processes that use chemicals to produce prints/slides from negative and/or transparency film.
  • Chlorobromide paper: Warm-tone printing paper. Uses emulsion containing silver chloride and silver bromide.
  • Chromatic aberration: A lens defect where the lens fails to focus different colours at the same point. Coloured fringes appear around objects, especially at the edges of the frame.
  • Chromogenic film: Films which form a final dye image rather than one of silver, when given appropriate dye-coupled processing (C-41 for example). Includes monochrome film designed to be processed with standard colour film chemistry.
  • CI: See Contrast index.
  • CIE: Commission Internationale de l’Eclairage. Originator of a standard system for precise description of colours.
  • Circles of confusion: Discs of light making up the image formed by a lens, from each point of light in the subject. The smaller these discs the sharper the optical image appears.
  • Clearing time: The time taken in a fixing bath for a film emulsion to lose its milky appearance. As a rule of thumb, most materials are fully fixed when twice the clearing time has elapsed.
  • Click stops: Aperture settings which you can set by physical ‘feel’ as well as by following a printed scale.
  • Clip test: Processing a small piece of film cut from one end of a roll to determine suitable processing times.
  • Cloning: Digital manipulation process where a small area of an image is copied and then superimposed on another spot.
  • Close-up: lens Additional element added to the main lens, to focus close objects.
  • CMOS: Complementary Metal-Oxide Semiconductor. A type of image sensor widely used in digital cameras. See APS and CCD.
  • CMYK: Cyan, magenta, yellow and key (black). The colour printing model predominantly used for mass produced printing material such as books and magazines. It can also be found in some inkjet and dye sublimation printers.
  • Coating (1): Transparent material deposited on lens glass to suppress surface reflections, improve image contrast.
  • Coating (2): Top layer of photographic or ink-jet paper which gives it a texture; matt, lustre or glossy, etc.
  • Cold-light (cold cathode) enlarger: Enlarger using a fluorescent tube grid. Gives bright, diffused illumination without producing a lot of heat.
  • Colour balance (film): Relates to the lighting under which a colour film is designed to record subject colours accurately. Typically expressed as daylight balance (5500 K) or tungsten light balance (3200 K); see Kelvin.
  • Colour balance (digital) In most digital cameras the colour balance is set automatically. You can also set it manually by photographing a neutral surface. The camera then calculates the Kelvin degree required.
  • Colour head: An enlarger lamp head with a colour printing filter system built-in.
  • Colour temperature: Way of defining the colour of a (continuous spectrum) light source, usually expressed in Kelvin (K).
  • Colour wheel: Diagram in which the colours of the visual spectrum are shown ‘bent’ into a circle, with each colour facing its complementary;
    Complementary colours Resulting colour (cyan, magenta or yellow) when one of the three primary colours (red, green or blue) is subtracted from white light. Also called ‘subtractive primaries’, ‘secondary colours’.
  • CompactFlash: Type of digital camera removable memory card.
  • Compound lens: One with more than one glass element. Virtually all photographic lenses are compound.
  • Compression Electronic: ‘squashing’ to reduce file size and therefore its storage needs, and minimize the time taken to transmit it via networks. Greatest compression can be achieved by means of ‘lossy’ methods such as JPEG, but at the cost of poorer image resolution.
  • Condenser: Simple lens system to concentrate and direct light from a source, e.g. in a spotlight or enlarger.
  • Contact print: Print made with paper exposed in direct contact with negative, therefore matching it in size.
  • Contrast: The difference between extremes: of lighting, of negative or print tone values, of subject reflectance range, etc. The greater the difference between extremes present together, the higher the contrast.
  • Contrast index: A numerical index relating image brightness range to resulting processed density range when ‘correctly exposed’ on the film’s characteristic curve.
  • Therefore relates to development and contrast. (Most general-purpose negatives to be printed on diffuser enlargers are developed to a CI of 0.56.)

  • Conversion filter: Colour filter used to compensate for differences between the colour temperature of the light source and the colour balance of the film, where the two differ.
  • Converter lens: Multi-element lens unit specially designed to (typically) double the focal length of each of a given range of long focal length camera lenses. Fits between prime lens and camera body.
  • Covering power: The area of image of useful quality that a lens will produce. Must exceed camera picture format, generously so if movements are to be used.
  • CPU: Central Processing Unit. Solid-state electronic chip housed within a computer or camera. In the camera it is used to compute exposure, focusing, etc., from data input by other electronic components. In a computer it translates, intercepts and executes instructions received as digital data, communicating with and transferring data between itself and all other internal circuits.
  • Cropping: To trim one or more edges of an image, usually to improve composition. Cropping tool A tool in image-editing software. Allows you to trim an image as you would mask the borders of an enlargement being made in the darkroom.
  • Cross front: Camera movement. Sideways shift of lens, parallel to film plane.
  • C-Type: A type of colour print made using light to convert a colour negative image into a positive one. Requires chemical processing. See Lambda and RA-4.
  • Curtin Sync: – First Shutter setting which fires the flash at the start of the exposure. The normal setting on most cameras.
  • Curtin Sync: – Second Shutter setting which fires the flash just before the end of the exposure.
  • Cut-off: Term describing the blocking-off of image light (‘vignetting’) usually at one or more corners of the picture format. May be caused by using the wrong lens on camera or enlarger, accessories such as lens hoods which are too small, or excessive use of certain camera movements.
  • Cyan: Complementary colour to red, composed of blue and green light.



  • Darkslide: Removable plastic or metal sheet fronting a sheet film holder or film magazine. Often used to describe the whole sheet film holder.
  • Daylight film: Colour film balanced for subject lighting of 5400–5500 K.
  • Daylight tank: Film processing container with a light trapped lid allowing development in normal lighting.
  • DCS: (Digital camera system) Prefix used for a number of Kodak camera models.
  • Dedicated flash: Flash unit which fully integrates with camera electronics. Ensures that the shutter speed is correctly set for flash; detects film speed, aperture, light reading, subject distance, etc.
  • Dense: Dark or ‘thick’, e.g. a negative or slide which transmits little light. Opposite of ‘thin’.
  • Densitometer: Electro-optical instrument for reading the densities of a film or paper image.
  • Density: Numerical value for the darkness of a tone on a processed film or paper.
  • Depth of field: Distance between nearest and farthest parts of a subject which can be imaged in acceptably sharp focus at one setting of the lens.
  • Depth of focus: Distance the film (or printing paper) can be positioned either side of true focus whilst maintaining an acceptably sharp image, without refocusing the lens.
  • Developing agent: Chemical ingredient(s) of a developer with the primary function of reducing light-struck silver halides to black metallic silver.
  • Dialogue box: On a computer a special window (often in fly-out form) which may appear on screen as part of a photo-manipulation program. It asks the user for information and/or commands before a task is completed.
  • Diaphragm: Variable diameter hole formed by an overlapping series of blades. See Aperture.
  • Differential focus: Using a small depth of field so only a selected part of the image is in sharp focus.
  • Diffraction: Minute change in the path of light rays when they pass close to an opaque edge. The cause of poorer image quality if a lens is used with an extremely small aperture.
  • Diffuser: Translucent material placed over a light source such as a studio light or enlarger bulb to make the light soft and evenly spread.
  • Digiscope: A device used to clamp a camera to a telescope or microscope so as to photograph the image directly off its eyepiece. Most commonly used with compact or small digital cameras.
  • Digital camera: A camera or camera back in which a CCD chip and supporting electronics replace film.
  • Digital image: An image defined by a stream of digitalized electronic data, typically made visible by display on a computer monitor screen.
  • Digitalize: Process of converting analogue data, which is continuously variable, into digital data represented by a code made up of combinations of only two (binary) digits, 0 and 1. In this binary form pictures can be processed by computer.
  • Dioptre (or Diopter): A measure of the strength, or light-bending power of a lens. The higher the dioptre, the greater the magnification, and the shorter the focal length.
  • DIN: Deutsche Industrie Normen. German-based system of film speed rating, much used in Europe. An increase of 3 DIN denotes twice the light sensitivity. Now replaced by ISO.
  • Dodging: See Shading.
  • DPI: Dots per inch. A measurement of the resolution of a computer scanner, monitor (72 dpi) or a printer (typically 300 dpi).
  • Dragging: Holding down the computer mouse button while moving it, to reposition items on the monitor screen, etc.
  • Dreamweaver: Software application from Adobe Systems Inc. used for building and managing websites.
  • Dry mounting: Bonding a photograph to a mount by placing dry, heat-sensitive tissue between the two and applying pressure and heat.
  • Drying mark: Uneven patch of density on film emulsion, due to uneven drying. Cannot be rubbed off but can sometimes be reduced by re-soaking.
  • D-SLR: Digital version of an SLR camera. See SLR.
  • DVD: Digital Versatile Disk. Recording medium physically the same size as a CD but capable of storing more data. See also Blu-Ray.
  • DVD-R: Recordable DVD with a capacity of 4.6 GB; see CD-R. DVD-RW Read/write DVD with a capacity of 4.6 GB; see CD-RW.
    DX coding Direct electronic detection of film characteristics (speed, number of exposures, etc.) Read from the chequer board pattern on a 35 mm film cassette by sensors in the camera’s film- loading compartment.
  • Dye-image: film See Chromogenic film.



  • E-6 process: Colour reversal processing procedure in widespread international use for most forms of colour slide/transparency film.
  • Easel: See Masking frame.
  • Edge numbers Frame number, film type information, etc., printed by light along film edges and so visible after processing.
  • Effective diameter: (of lens aperture) Diameter of the light beam entering the lens which fills the diaphragm opening.
  • Electronic flash: General term for common flash units which create light by electrical discharge through a gas-filled tube.
  • Element: A single piece of glass which is combined with others to form a lens of high quality. Emulsion The coating on film or paper. A mix of light-sensitive silver halides, plus additives, and gelatin.
  • EV: (Exposure value) A system used on some light metres. Each value expresses a series of shutter/aperture combinations all giving the same exposure effect, e.g. an EV of 12 means 1/250 @ f/4, or 1/125 @ f/5.6, or 1/60 @ f/8; EV 13 means 1/500 @ f/4, etc.
  • EXIF: Metadata embedded into a digital RAW file. Contains info such as shutter speed, aperture, etc. See RAW file.
  • Existing light: See Ambient light.
  • Expiration date :The ‘use by’ date found stamped on the packaging of most light-sensitive materials.
  • Exposure compensation: dial Camera control effectively overriding film speed setting (by up to 1 or 2 stops). Used when reading difficult subjects, or if film is later to be ‘pushed’ or ‘held back’ in processing to modify contrast.
  • Exposure Index (EI): Measure of sensitivity to light for practical use. Expressed as a film speed setting (ISO).
  • Exposure latitude: Variation in exposure level (over or under) which still produces acceptable results.
  • Extension tube: Tube, fitted between lens and camera body, to extend lens-to-film distance and so allow focusing on very close subjects.
  • Eyepiece projection: A method of photographing through optical devices such as telescopes or microscopes. The camera’s lens is positioned where the human eye would be, i.e. immediately behind the eyepiece and the image is formed by both devices in series.



  • f-numbers: International sequence of numbers, expressing relative aperture, i.e. lens focal length divided by effective aperture diameter. Each change of f-number halves or doubles image brightness.
  • f-stops: See f-numbers.
  • Farmer’s Reducer: An old name for a solution of potassium ferricyanide and hypo, used for bleaching tones on black and white prints and negatives.
  • Fast: Relative term meaning comparatively very light sensitive.
  • Feathered edge: In digital manipulation a command giving a soft (vignetted) edge to the whole image, or the area selected for cutting-out, darkening, etc. Helps avoid an obvious hard edge when printing-in or shading. Allows seamless montaging effects.
  • Ferrotype sheet: Polished metal plate used for glazing glossy fibre-based prints. Fibre-based paper Traditional type of photographic printing paper with an all-paper base.
  • Field camera: See Baseboard camera.
  • File: The term for a single document (e.g. a camera image) of digital data, as held on a storage device such as the computer’s hard disk or some form of removable disk. File format digital images need to be saved in a format that can be read by your software program(s). Typical image file formats are TIFF, JPEG and RAW (all bitmap file formats).
  • File size: The volume of image information forming the contents of a digital file. Becomes larger as the data from a digital image becomes more complex. Measured in kilobytes or megabytes.
  • Fill-in: Illumination that lightens shadows, so reducing contrast.
  • Film holder: Double-sided holder for two sheet films, used with view cameras. See Darkslide.
  • Film pack: Stack of sheet films in a special holder. A tab or lever moves each in turn into the focal plane, e.g. instant-picture peel apart material.
  • Film plane: The position in the back of the camera, in which the film lies during exposure. Film scanner Device for converting the (analogue) data of images on film into the digital data of image files. Incorporates a CCD array which scans the original.
  • Film speed: Figure expressing relative light sensitivity. See ISO.
  • Film writer/film recorder: Device to convert digital files into analogue images on silver halide photographic film, negative or transparency.
  • Filter: Optical device used on a lens to modify the image by altering its colour by absorbing selected wavelengths.
  • Filter factor: A measure of the amount of light absorbed by a filter, reducing image brightness.
  • Firewire: A common cable protocol (IEEE 1394) for downloading and sending digital data from a variety of external devices such as printers and cameras. A brand name of Apple Inc. Other names include Sony’s i.Link and Texas Instruments’ Lynx. Faster than USB and so favoured particularly for video.
  • Fisheye: Extreme wide-angle lens, uncorrected for curvilinear distortion.
  • Fixed focus camera: Camera (typically very simple type) with a non focus-adjustable lens. Usually set for its hyperfocal distance.
  • Fixer: Chemical solution which converts silver halides into soluble salts. Used after development and before washing, it removes remaining light-sensitive halides, retaining the developed black silver image.
  • Flare: Unwanted light, scattered or reflected within a lens or camera/enlarger body. Can cause uneven patches in the image, reduce contrast and degrade shadow detail.
  • Flashing: Giving a small extra exposure (to an even source of illumination) before or after image exposure. Lowers the contrast of the photographic material.
  • Flat: A subject or image lacking contrast, having minimal tonal range.
  • Flatbed scanner: Light box with an internal CCD array able to digitally scan-in photographic prints, etc. placed face down on its flat glass upper surface.
  • Flickr: An image-hosting website widely used by people sharing personal photos and video clips online.
  • Floodlight: Powerful artificial light source giving illumination over a wide area.
  • Focal length: Distance between the image and lens when the lens is focused for an infinitysubject. More precisely, between the image centre and the lens’s rear nodal point.
  • Focal plane: Plane on which a sharp-focus image is formed. Usually at right angles to lens axis.
    Fog Unwanted veil of density (or bleached appearance, in reversal materials). Caused by accidental exposure to light or chemical reaction.
    Format or ‘frame’ General term for the picture area given by a camera. See also Aspect ratio, and page 73.
  • FP-synch Setting or socket for specialist ‘focal plane’ flashbulbs.



  • Gamma: Tangent of the angle made between the base and straight-line portion of a film’s characteristic curve. Used as a measure of contrast.

  • Gamut
    : The range of colours reproducible by a particular display screen, inkjet printer or other digital imaging device.
  • Gel: Term used to describe large sheets of coloured material which act as filters over lights. Sometimes used to describe flexible acetate or polyester lens filters.
  • Gelatin: Natural protein used to suspend silver halides evenly in an emulsion form on film and paper. Swells to permit entry and removal of chemical solutions.
  • Giclée Print: A type of inkjet print of high quality and good archival stability.
  • Gigabyte (GB): Unit of computer memory equivalent to 1024 megabytes.
  • Gimp: (GNU Image manipulation Program) A freely distributed software program for working on digital images.
  • Gobo: Shape made from metal or cardboard which is added to the light source to project shadow effects such as window frames, tree branch effects, etc.

  • Gradation
    : Variation in tone. Tonal range or scale.
  • Graded papers: Printing papers of fixed contrast. You purchase the grade you need as indicated by a number on the packaging. The lower the number, the lower the contrast.
  • Gradient: Digital manipulation term for filling an area with a colour or grey tone which gradually changes in density across the filled zone.

  • Graduate
    : Calibrated container for measuring liquids.
  • Grain: Clumps of processed silver halides forming the image. Coarse grain reduces fine detail, gives a mealy appearance to even areas of tone.
  • Grey Card: Neutral mid-grey (18 percent reflectance) card used to simulate midpoint of the tones in an average scene for exposure and colour balance measurement.
  • Greyscale: A digital image containing only shades of grey, black or white.

  • Guide number
    : Number for simple flash exposure calculations, being flashgun distance from subject times the f-number required (when using ISO 100/21° film). Normally relates to distances in metres.
  • Gum Arabic: Glue used on the flaps of envelopes to seal them, and in some older 19th century alternative printing processes.



  • Half plate: Old glass-plate negative format. See Whole plate.
  • Halftone: Full tone-range photograph broken down into tiny dots of differing sizes, for ink reproduction on the printed page.
  • Halides: Alkali salts such as potassium iodide or potassium bromide, which when combined with silver nitrate form light-sensitive silver halides.
  • Hard: Contrasty – harsh tone values.
  • Hard disk/Hard drive High capacity magnetic disk, usually held internally in the computer,forming the main storage device for programs and image files.
  • Hardener: Chemical which toughens the emulsion gelatin to reduce the risk of damage from abrasion, etc. while washing.
  • High Definition: Video Any TV or video system with a resolution of higher than the standard of 640 × 480 pixels. Typical HD resolutions are 1280 × 720 or 1920 × 1080 pixels.
    High-end Digital equipment capable of capturing, manipulating, or outputting high resolution image files.
  • High key: Scene or picture consisting predominantly of pale, delicate tones and colours.
  • Highlights: The brightest, lightest parts of the subject or print.
  • Histogram: A bar chart graphically representing a digital image’s distribution of grey or colour tones.
  • Holding back: Reducing development (often to lower contrast). Usually preceded by increased exposure. Also called ‘pulling’. Term is sometimes used to mean shading or dodging when printing.
  • Home page: The opening page of a website. Introduces contents, and offers click-on links to other pages.
  • Hot shoe: Flashgun accessory clipping point built into the camera; it incorporates electrical contacts allowing the shutter and flashgun to synchronize. Generally a standardized design.
  • HTML: Hypertext Markup Language. A series of instructions which tell a web browser how to display website data. The ‘language’ in which websites are written.
  • Hue: A particular precise gradation of colour.
  • Hyperfocal distance: The closest subject distance which is acceptably sharp while the lens is focused on infinity. Setting the focus point at this distance extends the available depth of field to its maximum.
  • Hypo: Abbreviation for sodium hyposulphite, the fixing agent since renamed sodium thiosulphate. Also the common term for all fixing baths.



  • Icons: Small graphic symbols displayed on the computer monitor. These provide ‘click-on’ positions for your cursor to command applications, open or close files, activate tools, etc.
  • IEEE 1394: See Firewire.
  • Image stabilisation: System of motion sensors and moving optics or CCD used to minimize the effects of camera shake.
  • Incandescent light: Illumination produced from an electrically heated source, such as the tungsten-wire filament of a lightbulb.
  • Incident light: Light falling on a subject, surface, etc.
  • Incident-light reading: Using an exposure meter at the subject position, pointed towards the camera, with a diffuser over the light sensor.
  • InDesign: Software application from Adobe Systems Inc. used for book and magazine design and layout.
  • Indexical/Indexicality: The term indexical or ‘indexicality’ refers to the physical relationship between the object photographed and the resulting image, as opposed to a painting or print. [see the wikipedia entry for more]
  • Infinity: A subject so distant that light from it effectively reaches the lens as parallel rays. (In practical terms the far horizon.)
  • Infra-red (IR): Wavelengths longer than about 720 nm. Invisible to the naked eye and all but specialist films or CCDs.
  • Inkjet printer: Converts digital images into microscopic dots of ink on paper, so creating a final print in colour or monochrome.
  • Instant-picture material: Photographic material with integral processing. Intensification Chemical treatment of negative materials to increase image density and
  • Internet Service Provider (ISP): A company which provides you with access to the Internet.
  • Interpolation Increasing the apparent resolution of a digital image by averaging out nearby pixel densities and generating a new pixel in-between. (Cannot therefore truly provide additional detail.)
  • Inverse square law: The rule that says light intensity at a surface is inversely proportional to the square of its distance from the source, e.g. half the distance equals four times the intensity.
  • Inverted telephoto lens: A lens with rear nodal point well behind its rear element. It therefore has a short focal length but relatively long lens-to-image distance, allowing space for an SLR mirror system.
  • iPhoto: An image cataloguing and manipulation program from Apple Inc. Simpler and more basic than Aperture. Only available for the Mac platform.
  • IR focus: setting Red line sometimes located to one side of the lens focus-setting mark, used when taking pictures on IR film.
  • Iris: See Diaphragm.
  • ISO: International Standards Organization. Responsible for ISO film speed system. Combines previous ASA and DIN figures, e.g. ISO 400/27°.



  • JCII: Japan Camera Inspection & Testing Institute. Quality monitoring organization for Japanese optical equipment.
  • Joule: See Watt-second.
  • JPEG: Joint Photographic Experts Group. The name of a widely used image file format able to give a very high level of compression (e.g. to one-hundredth its original size). As a ‘lossy’ system it inevitably degrades some image quality.


  • Kelvin (K): Measurement unit of colour. Equals the temperature, absolute scale, to which a metal black body radiator would have to be heated to match the colour of the source. Named after the scientist Lord Kelvin.
  • Keylight: Main light source, usually casting the predominant shadows.
  • Kilobyte (KB): A measurement of digital file size, computer storage or memory space. One KB is 1024 bytes of information.
  • Kilowatt: Unit of (usually electrical) power. One thousand watts.



  • Lambda: A type of print made using lasers or LED systems to expose a digital image onto C-type or other analogue colour material.
  • Large format: General term for cameras taking pictures larger than about 6 × 9 cm.
  • Latent image: Exposed but still invisible image before processing.
  • Latitude: Permissible variation. Can apply to focusing, exposure, development, temperature, etc. LCD See Liquid Crystal Display.
  • Leaf shutter: See Between-lens shutter.
  • LED: Light-emitting diode. Tiny lamp used on equipment for light signalling – camera viewfinder information, battery check, etc.
  • Lens hood, or shade: Shield surrounding lens (just outside image field of view) to intercept side-light, prevent flare.
  • LightJet: See Lambda.
  • Light meter: Device for measuring light and converting this into exposure settings.
  • Lightroom Software application from Adobe Systems Inc. used for organising and manipulating digital images.
  • Light trap Usually some form of baffle to stop entry of light yet allow passage of air, solution, objects, according to application.
  • Lighting contrast ratio: The ratio between deepest shadow and brightest lit areas of a scene. Assumes that in both instances the tone of the actual subject remains the same (grey card in each area for example).
  • Line image: Very high contrast black/white image with no mid-tones at all, as needed for copies of line diagrams or drawings.
  • Linear perspective: Impression of depth in a picture given by apparent convergence of parallel lines, and changes of scale between foreground and background elements.
  • Liquid crystal display (LCD): Electronically energized panel used in film cameras to display settings, and in digital cameras to show the picture before and after exposure.
  • Lith (lithographic) film Highest-contrast film able to yield negatives with very intense blacks. For making line images.
  • Live Picture: A digital photo editing software package, [Macintosh Only] superior to Photshop, able to edit in a high bit depth and edit non-destructively, along with many other features photoshop has never adopted.
  • Live View: Feature on some digital SLR cameras which allows you to use the LCD screen as a viewfinder.
    Location photography Photography away from the studio.
  • Long focus lens: A lens of longer focal length than normal for the format. See Telephoto.
  • Long-peaking flash: Electronic flash utilizing a fast stroboscopic principle to give an effectively long and even peak of light. This ‘long burn’ allows a focal plane shutter slit to cross and evenly expose the full picture format, at fastest speeds.
  • Lossless compression: A non-destructive method of reducing the size of digital files. Avoids loss of quality relative to the original file when decompressed. TIFF is one such example.
  • Lossy compression: Method of greatly reducing digital file size by discarding data. Induces loss of quality of image when decompressed. JPEG is one such example.
  • Low key Scene: or picture consisting predominantly of dark tones, sombre colours. Lumen Unit of illumination or light output.
  • Lumen; A unit of luminous flux (power); the time rate of flow of visible energy emitted by a source or passing through a defined aperture.
  • Lux: The international system unit of illuminance; the luminous power per unit area incident on a surface. One Lux is equivalent to 1 lumen per square meter and to 1 meter-candle.



  • Macro lens: Lens specially corrected to give optimum definition at close subject distances. Macro setting A special, close focusing setting offered on some lenses (typically zooms).
  • Macro zoom: Macro lens which can also be varied in its focal length.
  • Macrophotography: See Photomacrography.
  • Magenta Complementary: colour to green, composed of blue and red light.
  • Magnification In photography:, means linear magnification (height of object divided into height of its image).
  • Manual mode: Selectable option on a multi-mode camera whereby you choose and make all the exposure settings.
  • Marquee tool: A computer image manipulation selection tool used to outline an area of an image with a broken line showing where changes are to be made.
  • Masking frame: Adjustable frame which holds printing paper flat during exposure under the enlarger. Also covers edges of the paper to form white borders.
  • Mat, or overmat: Cardboard rectangle with cut-out opening, placed over the print to isolate the finished picture.

  • Maximum aperture
    : The widest opening (lowest f-number) a lens offers.
  • Medium density fibreboard (MDF): A solid board available in various thicknesses made from wood fibres bonded together with synthetic resin adhesive. It is useful for mounting prints.
  • Medium format camera: Camera taking pictures larger than 35 mm but smaller than sheet film sizes. A 120 rollfilm camera, for example.
  • Megabyte (MB): A measurement of digital file size, computer storage or memory space. One MB is 1024 kilobytes of information.
  • Meta-data: Information recorded along with the image in some digital formats. See EXIF. Microphotography Production of extremely small photographic images, e.g. in microfilming of documents.
  • Mid-tone: A tone about mid-way between highlight and shadow values in a scene.
  • min/mins; An abbreviation for minutes, often used in charts listing development times for example
  • Mirror lens Also ‘Catadioptric’ lens. Lens using mirrors as well as glass elements. The design makes long focal length lenses more compact, less weighty, but more squat.
  • Mode: One of a series of settings on camera equipment which define how exposure or other settings are made. See Av, Tv and Program.
  • Modelling: light Continuous light source, positioned close to a flash tube, used to preview exact lighting effects before shooting with the flash itself.
  • Modem: Device to convert digital data from a computer into analogue form capable of being carried (as sound) over regular telephone lines. Also acts in reverse converting incoming analogue data back into digital data.
  • Monochrome: Single colour. Also general term for all forms of black and white photography.
  • Monorail camera: Metal-framed camera, built on a rail allowing a wide range of camera movements.
  • Motor drive: Motor which winds on film after each exposure.
  • M-synch: Flash setting for old type flashbulbs which delays the shutter opening to allow the bulb to reach its peak brightness.
  • MTF: Modulation Transfer Function. A comparative measure of the contrast of an image of a test chart with the original. Used in assessing lens performance.
  • Multigrade: See Variable contrast paper.
  • Multicoating: Microscopically thin layer on lens elements which reduces flare.
  • Museum board: A cardboard (used to make window mattes) which is free from chemicals that may reduce permanence of prints. Essentially it is acid-free board that has long-lasting permanence.



  • ND: See Neutral density filter.
  • Negative: Image on film in which tones are reversed relative to the original subject.
  • Negative sandwich: Two or more negatives placed in the enlarger at the same time to produce a print.

  • Neutral density filter:
    Colourless grey filter which simply dims the image by a known amount.
  • Noise: Defect by which shadows and other dark areas of a digital image contain pixels of the wrong colour, randomly distributed. Most often occurs in digital camera pictures which have been under exposed.
  • Normal lens: See Standard lens.
  • Notch code Notches on one edge of sheet film, shape-coded to identify film type.



  • Object The thing photographed. The same as Subject.
  • One-shot processing Processing in fresh solution, which is then discarded rather than used again.
  • On-the-fly A term used when referring to digital procedures that happen in real-time.
  • Opacity Incident light divided by light transmitted (or reflected, if tone is on a non-transparent base).
  • Opaque Impervious to light.
  • Open flash ‘Opening up’ Optical axis Firing flash manually while the camera shutter remains open. Changing to a wider lens aperture.
  • An imaginary line through the exact centre of a lens system.
  • Optical resolution In digital cameras the true maximum resolution possible is a product of CCD resolution and lens quality without resort to interpolation.
    Optimum aperture Lens f-stop setting which results in the highest image quality.
  • Ortho (Orthochromatic) Selective sensitivity to colours. An example of an ortho material is black and white printing paper, which is sensitive to the blue end of the spectrum, but does not react to red safe lighting.
  • OTF Off the film. Light measurement of the image whilst on the film surface during exposure – essential for through-the-lens reading of flash exposures.



  • P: See Program.
  • Pan and tilt head: Tripod head allowing smooth horizontal and vertical pivoting of the camera, usually with independent controls.
  • Pan film: See Panchromatic.
  • Panchromatic Material: equally sensitive to all parts of the visible spectrum.
  • Panning: Pivoting the camera to follow movement of the subject.

  • Panorama camera
    : Camera giving a long, narrow image covering a very wide horizontal angle of view. Specialist models can rotate to give up to 360°.
  • Parallax: Difference in viewpoint which occurs when a camera’s view finding system is in a position separate from the taking lens, as in compact and TLR cameras.
  • PC lens: Perspective control lens. A lens of wide covering power on a shift (and sometimes also pivoting) mount. See Shift lens.
  • PCMCIA card: Personal Computer Memory Card International Association card. (Also known as a PC card.) These removable cards include types I, II and III, and are used to store images or add extra functions to computers. In digital cameras they have been largely replaced by lesser capacity but smaller cards such as SmartMedia.
  • PE: European code for resin-coated paper. See RC paper.
  • Pentaprism: Multi-sided silvered glass prism. Converts the laterally reversed image on the focusing screen of an SLR camera to right-reading, as well as reflecting it to the eyepiece.
  • Perspective: The relationship of size, position and shape of three-dimensional objects as represented in two dimensions, i.e. a flat picture.
  • pH: Acid/basic scale. Spanning 0–14, based on the hydrogen ion concentration in a solution. 7.0 is neutral, e.g. distilled water. Chemical solutions with higher pH ratings are increasingly alkaline, lower ones acid.

  • Photo etching
    : A method of printmaking in which a metal plate has been coated with a light- sensitive material and exposed to light; the resulting image is then cut into the surface using an acid. Ink is then rubbed into the ‘cuts’ and transferred to paper.
  • Photoflood: Bright tungsten studio-lamp bulb. Usually 3400 K colour temperature.
  • Photogram: Image recorded by placing an object directly between sensitive film (or paper) and a light source. Similarly, objects placed on the top glass surface of a flatbed digital scanner.
  • Photomacrography: Preferred term for extreme close-up photography giving magnification of ×1 or larger, without use of a microscope.
  • Photomicrography: Photography carried out through a microscope.

  • Photoshop
    Software application from Adobe Systems Inc. used for manipulating digital images, drawbacks include ’rounding error’ and ‘destructive editing’, see Live Picture.
  • Pinhole camera: One which uses a very small hole in place of the lens. Images are typically less sharp and much dimmer than those made by a lens.
    Pixel PICture ELement. The smallest element making up a visual digital image.
  • Pixellated: A digital image which has been enlarged to the point where the pixels are clearly visible as individual blocks of colour or tone.

  • Polarized light
    : Light waves restricted to vibrate in one plane at right angles to their path of direction.
  • Polarizing filter: Grey-looking filter; allows light waves vibrating in only one plane to pass through.

  • Polaroid
    :. Instant picture company which made ‘self-processing’ pictures from 1947 to 2009. The term is still often used to mean any instant picture film.
  • Polaroid back: Camera magazine or film holder accepting instant-picture material.
  • Positive Image: with tone values similar to those of the original subject.

  • PQ
    : Developer using phenidone and hydroquinone as developing agents.
  • Preservative Chemical ingredient of a processing solution. Maintains its activity by reducing oxidation effects over time.

  • Press focus
    Lever on most large-format camera shutters. Locks open the shutter blades to allow image focusing.
  • Primary colours Of light: red, green and blue.
  • Printing-in (also known as Burning-in): Giving additional exposure time to some chosen area, during printing.

  • Program, programme, or P Setting
    : mode for fully automatic exposure control. The camera sets both aperture and shutter settings based on its own built-in program(s).

  • Pulling
    : See Holding back.
  • Push-processing: Increasing development, usually to improve speed or increase contrast.


  • Q-Lab: An auditing service for professional processing labs run by Kodak to ensure quality standards.
  • Quarter plate: See Whole plate.
  • Quartz iodine (QI): Compact tungsten filament lamp. Gives high light output for its wattage and maintains colour temperature and intensity throughout its life.



  • RA-4: The commonest chemical process used to process colour print materials such as C-type. Usually automated.
  • RAM: Random access memory. Temporary memory used within a computer when it is switched on. Large amounts of RAM are required by a manipulation program in order to run its many image changes.
  • Rangefinder: Optical device for assessing subject distance, by comparison from two separate viewpoints.

  • Rapid fixer
    : Fast-acting fixing bath using ammonium thiosulphate or thiocyanate as the fixing agent.
  • RAW file: The untouched digital file straight from the camera CCD without any adjustment by built-in camera software.

  • RC pape
    r: See Resin-coated paper.

  • Rebate
    : The unexposed edge of a negative, often printed with frame numbers, etc.

  • Reciprocity law
    : Exposure equals intensity multiplied by time. This relationship breaks down at extremely long (and short) exposure times, known as Reciprocity failure.
  • Redhead: A tungsten lamp rated at 800 watts. The name comes from the red housing. Reducer Chemical able to lower the density of a processed image. (Paradoxically the term
    ‘reducing agent’ is also applied to developing agents.)
  • Reflected-light reading: Measuring exposure (often from the camera position) with the light sensor pointing towards the subject.
  • Reflector: Surface used to bounce light.
  • Reflex: camera Camera using one or more mirrors in its viewfinder system.
  • Refraction: Change in the direction of light as it passes obliquely from one transparent medium into another of different refractive index, e.g. from air to water.
    Relative aperture See f-numbers.
  • Remote control: Alternative to a cable or electric cord release on newer cameras using infra-
    red signals to fire the shutter.
  • Removable (external) hard disk: Storage medium for digital data which you can physically transport and connect to another computer to download its information.
  • Replenisher: Solution of chemicals (mostly developing agents) designed to be added in controlled amounts to a particular developer, to maintain its activity and compensate for repeated use.

  • Resin-coated paper
    : Printing paper which differs from the fibre-based type by the addition of a clear resin (plastic) coating which reduces the amount of chemistry absorbed, reducing processing times.
  • Resolution (1): Digital image quality as measured by multiplying the number of horizontal and vertical pixels. Results in a figure for resolution in pixels per inch.
  • Resolution (2): Ability of a lens to record fine detail, sometimes referred to as resolving power, expressed in lines per mm.
    Resolving power See Resolution (2).
  • Restrainer: Chemical component of developer which restrains it from acting on unexposed halides.

  • Reticulation
    : A ‘wrinkly’ overall pattern created in an emulsion during processing, due to extreme changes of temperature or pH. More common in older films.

  • Retouching
    : The process of manually altering an image to add or remove details. Often used interchangeably with ‘Spotting’ though that is restricted to eliminating defects such as dust marks.
  • Reversal system: Combination of emulsion and processing which produces a direct image of similar tonal values to those of the picture exposed on to the material. A typical example is a colour transparency (slide).
  • RGB: Red, Green and Blue. The colour mode used on all screens and most inkjet printers. Each colour reproduced is a mixture of red, green and blue.
  • Ring flash: Circular electronic flash tube, fitted around the camera lens yielding even, almost shadowless illumination.
  • Rising front: Camera design feature which allows the lens to be raised, parallel to the film plane. Rollfilm Any film larger than 35 mm which comes as a roll. Typically 120, 220 or 620 film formats.
  • Rollfilm back: Adaptor back allowing rollfilm to be used in a larger-format camera.
  • ROM: Read-only memory. A type of computer memory able to store data which can be read later but cannot be subsequently amended. Used to contain the basic code that allows the central processing unit to work. See CD-ROM.



  • Sabattier effect: The result of re-exposing film or a print to light before development is complete, sometimes known as pseudo-solarization.
  • Safelight: A darkroom working light of the correct colour and intensity not to affect the light- sensitive material in use, e.g. red/orange for regular blue-sensitive bromide paper.
  • Saturated: colour A strong, pure hue – undiluted by white, grey or other colours.
  • Scanning back: A device which operates much like a flatbed scanner. Mounted at the back of a 5 × 4 in. camera, it slowly scans the scene in front of it. Mostly used in a controlled studio environment and for archival purposes such as museums.
  • Scanner: Device for converting existing (analogue) images – photographic prints, negatives, slides, etc. – into digital form.
  • Scrim: Metal or glass fibre mesh attachment to the front of a lighting unit which reduces intensity without altering lighting quality or colour.
  • Search engine: A website through which one can search for content on other websites by inputting keywords.
  • secs: An abbreviation for seconds, often used in charts for developing film or paper.
  • Secondary colours: See Complementary colours.
  • Selective focusing: Precise focus setting and shallow depth of field, used to isolate a chosen part of a scene.
  • Self-timer: Delayed-action shutter release.
  • Sensitometry: Scientific analysis of the behaviour of photographic materials in their response to exposure and development.
  • Sepia: A colour ranging from reddish brown to chocolate, as formed in toning processes by different combinations of toner and silver halide emulsion. Also an option in some digital image processing software.
  • Shading: Blocking off light from part of the picture during some or all of the exposure, usually in printing
  • Shadows: In exposure or sensitometric terms, the darkest tones in the subject.
  • Sharp: In-focus and not blurred.
  • Sheet film: Light-sensitive film in the form of single sheets.
  • Shift camera: General term for a bellowless, wide-angle lens architectural camera with movements limited to up/down/sideways shift of the lens panel. No pivots or swings
  • Shift lens: Wide-covering-power lens in a mount permitting it to be shifted off-centre relative to the optical axis. Useful in cameras lacking movements. Some models allow the lens to be tilted in relation to the image plane too.
  • Shutter: Mechanical device used to control the time of exposure in the camera.
  • Shutter-priority: mode See Tv.
  • Silhouette: An image showing the subject as a solid black shape against white background.
  • Silicone release paper: Heatproof non-stick sheet used in dry mounting to prevent the print adhering to the press.
  • Silver halides: Light-sensitive compounds of silver and alkali salts of halogen chemicals, such as bromine, chlorine and iodine.
  • Single-use camera: Simple, ready-loaded camera, broken open and disposed of by the lab when processing your exposed film.
  • Slave unit: Electronic device which reacts to light from another flash and fires a second unit simultaneously.
  • SLR: Single-lens reflex.
  • SmartMedia: A PC card which fits into a digital camera or (typically through an adaptor) into a computer or printer to allow storage or transfer of data.
  • Snoot: Conical black tube fitting over a spotlight or small floodlight. Restricts lighting to an even, circular patch.
  • Soft: (1) Low contrast.
  • Soft: (2) Slightly unsharp or blurred.
  • Solarisation Reversal (either partially or totally) of the tones in a photograph caused by massive over-exposure, often during processing. Now an effect in some digital image manipulation programs.
  • Spectrum: Radiant energy arranged by wavelength. The visible spectrum, experienced as light, spans 400–700 nm.
  • Specular reflection: Light which is perfectly reflected, as by a highly shiny surface such as a mirror, glass, smooth water etc.
  • Speed (of emulsion): A material’s relative sensitivity to light.
  • Spherical aberration: Lens defect which causes the image to be formed in a partially curved instead of flat plane resulting in poor image definition over the whole area. Effects can be reduced by using a small aperture to increase depth of focus.
  • Spill kill: Small reflector/light control ring which stops the spread of light in all directions. Often used in conjunction with an umbrella reflector.
  • Spot meter: Hand meter, with aiming viewfinder able to pick out small areas of (often distant) subjects and so make precise exposure readings.
  • Spot mode: A TTL metering mode option which allows a narrow-angle exposure reading of the subject. The small area measured is outlined on the camera’s focusing screen.
  • Spotting Retouching-in small, mainly white specks or hairs – generally on prints – using water- colour, dye or pencil. Can also be performed digitally using image manipulation programs.
  • Squeegee: Rubber blade or roller device used to remove water from the surface of prints, etc.
  • Stabilisation: Chemical process used either instead of or in addition to fixing. Undeveloped halides are converted to more stable compounds either to reduce washing times or to increase material longevity.
  • Standard lens: The lens most regularly supplied for the camera size; typically has a focal length equal to the diagonal of the picture format. Covers a field of view roughly the same as the human eye.
  • Still-life: General term for an inanimate object, set up and arranged in or out of the studio.
  • Stock solution: Chemical stored in concentrated liquid form which is then diluted for use.
  • Stop: Correctly used means aperture but commonly used to mean an increment of half or twice the exposure value. See f-numbers.
  • Stop bath: Acidic solution which halts development, and reduces fixer contamination by the alkaline developer.
  • Stopping down: Changing to a smaller aperture (higher f-number).
  • Strobe: Old, mainly US general term for electronic flash. (Was a trade name for a manufacturer of studio flash equipment.) Strictly it means a fast-repeating stroboscopic lamp or flash which may fire many times a second.
  • Subject: The thing being photographed. Term used interchangeably with object, although more relevant to a person, scene or situation.
  • Subject brightness range: The ratio between the most brightly lit reflective part, and the most dimly lit dark toned part of the subject appearing in your picture.
  • Supplementary lens; See Close-up lens.
  • Sync lead: Cable connecting flashgun to camera shutter, for synchronized flash firing.
  • Synchro-sun: Flash from the camera used to ‘fill-in’ shadows cast by sunlight.



  • T: Setting ‘Time’ setting available on some large-format camera shutters. The release is pressed once to lock the shutter open, and then pressed again to close it.
    Technical camera See View camera.
  • Tele-converter: See Converter lens.

  • Telephoto
    : Long focal length lens with shorter back focus, allowing it to be relatively compact.
  • Tempering bath: Large tank or deep tray, containing temperature-controlled air or water. Accepts drums, tanks, bottles or trays to maintain their solution temperature before and during processing.
  • Terabyte: 1024 gigabytes.
  • Test strip: Full or part sheet of photographic paper given a number of different exposures to help determine the correct print setting.
  • ‘Thick’ image: Dense, dark result on film.

  • ‘Thin’ image
    : Pale, ghost-like film, lacking density.
  • Thumbnail: Small version of a larger digital image used a visual reference for locating and identifying image files on a computer or printed reference sheet. See Icons.
  • Thyristor flash: Automatic sensor on a flashgun which measures the light reflected from the subject during exposure and cuts off the power when exposure is deemed correct.
  • TIFF: Tagged Image Format File. Extensively used file format for high-resolution digital images. Tilt and Shift lens See Shift lens.
  • Tinting: Applying colour (oils, dye, watercolours) to a print by hand.
  • TLR: Twin-lens reflex.
  • Toning: Converting a black silver image into a coloured compound or dye. The base remains unaffected.

  • Transparency
    : Positive image on film. Includes both 35 mm slides and larger formats.
  • TTL: Through-the-lens camera reading, e.g. of exposure.
  • Tungsten-light film: Colour film balanced to suit tungsten light sources of 3200 K.
  • Tv: Time value. Auto-exposure camera metering mode. You choose the shutter speed; the meter sets the aperture. (Also known as shutter priority system.)



  • Ultraviolet Wide band of wavelengths less than about 390 nm. Invisible to the human eye.
  • Undo A digital manipulation program command which reverses the last editing command you applied to an image. Programs offering multiple Undo allow you to work backwards over a number of commands.

  • ‘Universal’ developer
    A developer designed for both films and prints (at different dilutions).
  • Unsharp masking (digital) Selective sharpening of the image in areas of high contrast, with little effect on areas of solid tone or colour. An effective method of improving the visual appearance of sharpness and detail.
  • Uprating Increasing the film’s speed setting (or selecting a minus setting on the exposure compensation dial) to suit difficult shooting conditions. Followed up with extended development.
  • USB Universal Serial Bus. A very common cable protocol for downloading and sending digital data from a variety of external devices such as printers and cameras.
    UV filter Filter absorbing ultraviolet light only. Appears colourless.



  • Vanishing point: The point on the horizon where parallel lines seem to meet in a two-dimensional image.
  • Variable contrast paper: Monochrome printing paper which changes its contrast characteristics with the colour of the exposing light. Controlled by filters. Multigrade; Polygrade; Varigrade and Polymax are all trade names for variable contrast papers.
  • VGA: Video Graphics Array. The established standard term for digital resolution of 640 × 480 pixels. Found in low-end cameras used as computer peripherals.
  • View camera: Camera (usually large format) in which the image is viewed and focused on a screen in the film plane, later replaced by a film holder. View cameras are primarily used on a stand or tripod.
  • Viewpoint:, The position from which the camera views the subject
  • Vignetting edges: Fading off the sides of a picture into plain black or white, instead of having abrupt.



  • Warm tone: A brownish black and white silver image.
  • Watt: Unit of power, usually in electrical devices.
  • Watt-second: Light output given by one watt burning for one second. Used to quantify and compare the power output of electronic flash (but ignores the influence of flash-head reflector or diffuser on exposure).
  • Wetting agent: Detergent-type additive, used in minute quantity to lower the surface tension of water. Assists even action of most non-acid solutions, and of drying.
  • White balance: Automatic or manual adjustment to a digital camera’s CCD colour response. Ensures correct colour balance in images shot under lighting of various colour temperatures.
  • White light: Illumination containing a mixture of all wavelengths of the visible spectrum. Whole plate An obsolete film and paper format measuring 6.5 × 8.5 in. Half-plate and quarter-plate sizes were also manufactured.
  • Wide-angle: lens Short focal length lens of extreme covering power, used to give a wide angle of view.
  • Wide-carriage: printers Inkjet printers capable of outputting poster-size colour prints, e.g. over a metre wide and of unlimited length.
  • Window matte: Cardboard surround used to frame photographic images when behind glass.
  • Working solution: Liquid chemical at the dilution strength actually needed for use.
  • WWW: World Wide Web. That part of the Internet which involves servers to be able to communicate with other computers on global telecommunication networks. Provides an infinite web of links to information stored in hundreds of thousands of servers all over the world. Makes possible electronic publishing.



  • X-synch: Setting or socket for electronic flash.



  • Zone system: Method of controlling final print tone range, starting with your light readings of the original subject. Pictures are previsualized as having up to nine tone zones, adjusted by exposure and development. Propounded by photographers Ansel Adams and Minor White.
  • Zoom lens: Lens continuously variable over a range of focal lengths, while maintaining the same focus setting.
  • Zoom range: The relationship of longest to shortest focal lengths offered by a zoom lens, e.g. ×2, ×3, etc.
  • Zooming: Altering the focal length of a zoom lens.