Glossary

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This is a growing glossary of common camera and photography terms. Feel free to add items that aren't listed by using the "edit" tab at the top of the screen.

0 to 9

  • 2-way head - a tripod head that moves about two axes; this design is older but is still often used in sports photography or by others using long, heavy lenses.
  • 3-way head - a tripod head that moves about three axes allowing the camera to be directed in more or less any direction relative to the tripod.
  • 35mm - a film 35mm wide with large perforations at each edge; most commonly this is used for 24×36mm frames on a roll of film wound from and subsequently back into an easy-to-load cassette.
  • 35mm equivalent - the focal length of a camera lens, scaled according to the size of the film or digital sensor relative to that of a 35mm camera.

A to B

  • achromat - a lens corrected for chromatic aberration to some extent.
  • actinometer - a light meter that works by actinometry.
  • actinometry - measuring light by the speed of a photo-chemical reaction.
  • adapter
  • air release - a remote control shutter release similar to a cable release, worked by air pressure - usually consisting of a piston attached to the shutter, with a rubber tube leading off to a rubber bulb which is squeezed to fire the shutter.
  • analog - widely used to refer to cameras and photography that are not digital (i.e. using film).
  • Anastigmat - a class of lens, corrected for astigmatism
  • APD - "auto preset aperture" - See PAD
  • aperture - an opening in a lens that controls the amount of light passing through it.
  • aperture priority - a mode of automatic exposure, in which the user selects the aperture, and the camera's meter selects the shutter speed.
  • aspect ratio - the relative sizes of height and width to each other; e.g. of film, sensor, computer monitor / LCD or prints
  • aspherical – lens surfaces whose shapes are more complex than the spherical curves which are simplest to manufacture; desirable in some designs for improved aberration correction
  • auto exposure - an in-camera exposure system that attempts to set the aperture and shutter speed (and CCD sensitivity in many digital cameras) to get the best exposure for the current lighting situation.
  • autofocus - the ability of any camera/lens to focus itself electronically to the appropriate image subject distance.
  • autographic - a feature allowing hand-written comments on the negative. 1914-1934
  • auxiliary lens - a lens that attaches to the front of another lens to change the field of view (narrower, wider) or focusing characteristics (able to focus more closely).
  • back - the rear compartment of a camera, containing the recording media; in some cases, this is a removable module.
  • Bakelite - an early form of plastic, used in camera making from the 1930s to the 1960s.
  • ball head - tripod head based around a lockable, free-moving ball.
  • barn doors
  • barrel
  • barrel distortion - a lens defect, in which straight lines near the edge of the frame are made to bow outward in the image. See its opposite, pincushion distortion.
  • batteries
  • Bay I - bayonet type I. A type of filter/hood mount commonly used on TLRs.
  • Bay II - bayonet type II. A type of filter/hood mount used on some TLRs.
  • Bayer filter – a mosaic of tiny red, green, and blue color filters placed over the individual pixels of a digital sensor. After demosaicing, this allows the (essentially color-blind) silicon cells to record the color information of the scene.
  • bellows
  • body cap - a cap to close the lens mount, and keep dust out of the camera when the lens is removed from the body.
  • bokeh - a term for the way a lens renders unsharp/out-of-focus image areas; taken from the Japanese for 'out of focus'.
  • bounce flash - reflecting a flash from a wall or ceiling (or perhaps a special flash diffusing reflector, such as a brolly) to soften the harsh shadows and contrast produced by direct flash.
  • box camera - a class of simple cameras, commonly shaped as cuboid boxes.
  • bulb mode ('B' shutter) - a shutter setting where the shutter stays open as long as the release is held. 'Bulb' refers to the hand-bulb used to open a pneumatic shutter release with early cameras, not to a flash bulb.
  • bracket - to expose at several levels of any setting (usually shutter speed or aperture, but the term can also apply to focus distance, filter strength or white balance), to increase the chance of getting one acceptable picture.
  • bridge camera - originally an SLR with a fixed zoom lens; nowadays a medium-size digital wide-range zoom camera with electronic viewfinder (EVF), intermediate between the compact camera and SLR
  • brilliant finder - a simple reflex finder with a condenser lens, giving a bright view. Typically these are very small (as on many box cameras), but some TLRs have full-frame brilliant finders.
  • brolly - another name for an umbrella.

C to D

  • C-41 - the standard development process for color negative film
  • cable release - an attachment that screws into a shutter release that allows you to trip the shutter mechanically while not otherwise touching the camera.
  • camera
  • camera shake - a blurring of a photo due to the camera moving - usually unintentionally.
  • camera system
  • cassette film
  • CCD - Charge-Coupled Device - a component that can be used as the light sensor in analog-electronic or digital cameras.
  • CdS - Cadmium Sulphide - a type of light meter cell.
  • center-weighted - an in-camera light-meter system that favors the center of the frame although it does take into account the rest of the frame to a lesser extent.
  • [chambre à joues]] - a type of strut-folding camera.
  • chromatic aberration - a type of lens distortion in which different colors focus at different convergence points
  • circle of confusion - diameter of the blur disk when a pinpoint of light is somewhat misfocused; the largest circle of confusion which is not noticeable is one factor in calculating of depth of field
  • CLA - Clean, Lubricate and Adjust
  • click stops - See also detents.
  • clone - equipment made, under license from original manufacturer, by another manufacturer.
  • coated - refers to a lens whose air-glass surfaces have had anti-reflection coatings applied, for reduced flare and improved contrast
  • collapsible lens - a lens which can retract into the camera body to save space
  • color balance
  • color-blind - the most basic black and white photographic emulsion, sensitive to violet and blue light only.
  • colour temperature
  • compact camera
  • Compur - a brand of camera shutters, made by the F. Deckel company of Munich, Germany.
  • contact print - a print of a negative made by laying the film directly on the paper and exposing to light.
  • contrast
  • convertible lens (or combinable lens) - a lens made from two or more groups of elements, which can be used alone or in combination, to give a choice of focal lengths.
  • Copal - a brand of Japanese camera shutters.
  • coupled rangefinder - a rangefinder which is mechanically connected to the focus control of the camera/lens, so the two are adjusted together.
  • crop - to reduce a picture to a smaller area, cutting off the edges - usually to leave a better composition.
  • cross processing - developing a film using a process intended for a different kind of film - i.e. using the "wrong" process; done for the special effects this produces, such as wild colour changes.
  • CSC – "Compact System Camera," a digital model offering interchangeable lenses (and other accessories); but distinguished from DSLRs by the absence of a reflex finder. See also EVIL and MILC.
  • CMY, CMYK - cyan, yellow, and magenta are the "subtractive" primary colors, the basis for reproducing color images using ink on paper. While mixing CMY ink colors would create a (near) black, in practice a separate "K" black ink component is used in printing.
  • data back - a camera back for film cameras that imprints (or burns) information (typically a date or serial number) onto a film frame.
  • dark slide - a holder for sheet film (or glass plates), typically for a view camera. The holder is loaded in the darkroom, and holders can then be exchanged in daylight in the studio or in the field. Originally the term refers to the sliding cover of such a holder. The cover can be opened once in the camera, to expose the film to the lens.
  • demosaicing – a software interpolation process required to reconstruct color values for each individual pixel in a digital sensor, when it is equipped with a color filter array such as the ubiquitous Bayer filter
  • depth of field - the range of distances over which subjects will be considered to be "in focus" (within which the circle of confusion will be acceptably small); affected by aperture and degree of enlargement.
  • detents - 'click stops'; positions at which a control (a dial, aperture ring, etc.) stops readily, and offers slight resistance to further adjustment. This is usually achieved by a captive spring-loaded ball bearing.
  • diaphragm - the mechanism in a camera lens that creates a variable aperture.
  • diffraction - bending of light as it passes a sharp edge (such as the edge of a camera's iris diaphragm). Diffraction is due to light's wave-like nature, and imposes an irreducible limit on resolution.
  • digital film - the picture storage medium used in a digital camera.
  • digital zoom - a method of zooming via cropping and upsizing instead of physical lens adjustment
  • diopter - the unit of refractive power of a lens. By extension, it has become used as a term for a corrective lens adjusting a viewfinder for the user's eyesight.
  • digital camera
  • distortion - lens defect resulting in straight lines appearing curved
  • DNG – an open standard raw image format created by Adobe, intended to insure ongoing accessibility of original digital-image sensor data.
  • dot - each individually-addressable element of a display matrix; typically one red, one green, and one blue dot are needed for each pixel.
  • double exposure - intentional or unintentional action of exposing the same film frame twice.
  • DR Mode - program mode on Ricoh cameras.
  • DSLR - Digital Single Lens Reflex camera

E to F

  • E-6 - the modern standard development process for color reversal (slide) film.
  • element - an individual piece of glass within a lens.
  • E-TTL - Evaluative Through The Lens flash metering exposure system: a metering method used by Canon cameras, where a short "pre-flash" illuminates the scene to calculate the exposure for the main flash.
  • everset shutter - a leaf shutter that does not need cocking (or rather, pressing the lever first cocks, then releases it). It is tripped by the energy of the finger pressing the release. Everset shutters cannot provide high speeds, the release must be pressed harder than with a cocking shutter.
  • EVF - Electronic View Finder: LCD-preview screen that is viewed through an ocular, first used in digital bridge cameras, and now increasingly as a replacement for reflex finders.
  • EVIL - acronym for "Electronic Viewing, Interchangeable Lens"; somewhat joking term for the class of digital camera systems which do not use true SLR viewfinders.
  • EXIF - a specification for digital image file storage
  • EXIF data is information about a digital photo embedded in the file.
  • exposure - the act of allowing light to fall on the film or sensor, and by extension, the combination of the camera's settings used to do so: shutter speed, aperture and film speed.
  • exposure compensation - increasing or decreasing the exposure to compensate for dark or light subjects which may cause a light meter to indicate the "wrong" exposure.
  • Exposure Value (EV) - an expression of the combination of shutter speed and aperture in a single number. Related to (but not identical to) Light Value (LV)
  • extension tubes - tubes inserted between the camera and lens, to move the lens further from the focal plane and so allow closer focusing.
  • f-stop - a measure of the diameter of the aperture on a lens, expressed as a fraction of f, the focal length.
  • field camera - a large format camera, slightly stripped down to make it more portable; typically folding.
  • field of view - the scene that is visible with a given lens, usually expressed in angular terms.
  • film advance - the mechanism for moving roll film forward by one frame-length after exposure. This is typically based on a knob, a thumb-lever, a crank, or clockwork or electric motor.
  • film chamber - the rear part of the camera that houses film.
  • film pack - a pack holding 12 sheets of film
  • film plane - the plane at the back of a camera in which the film is held for exposure, and onto which the image is focused.
  • film speed - the sensitivity of a film to light, expressed on any of several scales.
  • filter
  • filter rings
  • filter thread - a screw-thread inside the front of a lens to allow filters to be attached.
  • finder - short for viewfinder.
  • fisheye - a fisheye lens has a very wide field of view, up to 180 degrees.
  • fixed-focus - without a focus control (referring to a camera or its lens). A fixed-focus lens is dependent on depth of field
  • flange focal distance - measurement of the distance from the focal plane to the front of the lens mount; a key parameter of different lens-mount standards
  • flare - occurs when light enters the lens that isn't part of the image and then subsequently hits the camera's film or digital sensor.
  • flash
  • flashbulbs - single-use bulbs for flash photography.
  • flash meter
  • flash synchronisation - the manner in which the firing of a flash is delayed until the shutter is completely open. Different flash equipment (especially bulbs versus electronic flash) require different delay (because bulbs do not fire instantaneously). Focal-plane shutters cannot synchronise at their fastest speeds (because the shutter opening becomes a slit, and is never completely open).
  • flash trigger
  • fluid head - a tripod head often used in video production, designed to dampen movements to ensure smooth panning.
  • focal length - a measure of the image magnification given by a lens, and hence the angle of coverage it provides.
  • focal plane - the plane onto which a lens focuses its image.
  • focal-plane shutter - a shutter consisting of fabric or metal "curtains", that operates just in front of the focal plane (right in front of the film), and capable of high speeds.
  • focus - to adjust the lens to give a sharp image of a subject a certain distance from the camera.
  • focus free - a term used in advertising for fixed-focus cameras, seeking to make a virtue of the feature.
  • focus peaking – a focusing aid found on certain digital cameras, outlining the sharpest areas of an image with a false-color halo.
  • focus rail
  • focusing screen - a piece of ground-glass on which the focused image can be viewed, directly or through an eyepiece, to assist while focusing. A focusing screen is used at the back of a view camera, and exchanged before exposure for a film-holder. TLR and SLR cameras also use ground-glass focusing screens, often with built-in prismatic focusing aids.
  • fogging - degradation of a photograph caused by stray light leaking onto the film or sensor, by faults in developing, usually resulting in white areas on the final (positive) image.
  • frame counter - a mechanism for indicating the number of exposures made (or sometimes the number remaining) on a roll of film or memory card.
  • front curtain sync - in an SLR, firing of the flash at the moment when the front curtain is open.
  • front-element focusing - focusing by adjusting only the front element of some triplet and Tessar lenses, where this is mounted on a screw thread for this purpose (as opposed to 'unit focusing' - moving the entire lens assembly via bellows or a helicoid, or moving the film plane, as in the Mamiya Six and Ensign Commando).
  • fungus - any of a large group of organisms. Once thought of as plants, fungi are now considered a kingdom in their own right. Some fungi can grow on the surfaces of lens elements, resulting in feathery growths, and even permanent etching of the surface.

G to H

  • GOST - a film speed scale used in the Soviet Union.
  • grain
  • ground glass - a glass plate frosted (originally by grinding with an abrasive; more recently it may be made by chemical etching) to make a translucent surface on which an image may be focused, and viewed from the other side. Ground glass is used in viewfinders and focsing screens
  • grain focuser - a viewer in which the image from an enlarger is seen via a mirror and enlarging eyepiece, so that the highly-enlarged image of the silver grain in the negative can be used for very accurate focusing.
  • greyscale image - an image made up only of shades of grey, i.e. a (so called) black-and-white image.
  • guide number - a measure of the power of a flash gun, with dimensions of distance.
  • hand camera - a camera intended to be used in the hand (as opposed to a 'stand' camera) - a term current in the 19th and early 20th centuries.
  • half-frame
  • handle mount flash
  • HDR - High Dynamic Range imaging; processing images to a higher dynamic range of luminances, increasing the difference between light and dark.
  • Hippie strap - a wide, multi-colored, woven cloth strap, suitable for distributing the weight of a full-sized SLR camera.
  • histogram - a bar-chart; in digital cameras, such a chart showing the distribution of different light-levels in an image.
  • hot lights
  • hot shoe - an accessory shoe with built-in flash synchronisation contacts; by back-construction, a shoe without trigger contacts is sometimes called a cold shoe.

I to K

  • image stabilization
  • infinity focusing
  • instant camera - a camera producing finished pictures, directly from the camera within a short time of taking. See Kodak Instant, Polaroid and Fujifilm instant photography.
  • instant film - media for instant cameras; packs containing the sensitive materials and the chemicals to develop them.
  • instant-return mirror - a mirror in an SLR that automatically returns to the viewing position after an exposure, and so restoring the view through the viewfinder; true instant-return mirrors function whatever the position of the shutter button (raised or pressed)
  • isochromatic - black and white emulsion with low sensitivity to deep red color.
  • isoorthochromatic - a variant of the black and white orthochromatic emulsion with equalized sensitivity to green and yellow light.
  • isopanchromatic - a variant of the black and white panchromatic emulsion with equalized sensitivity to green and yellow light.
  • jumelle (or photo-jumelle) - a style of camera common around the turn of the 20th century, usually with a rigid, tapered body thought to resemble a pair of binoculars.

L to M

  • landscape format - (of rectangular pictures) oriented with the long edge horizontal.
  • large format - film format larger than medium format, in which sheet film (or previously plates) are loaded one at a time rather than as rolls. The smallest common large format is now 4x5 inch. Smaller cameras might be considered large-format, if they use sheet film.
  • leaf shutter - a shutter mechanism, usually mounted in the lens, that uses overlapping metal blades.
  • LED - Light-Emitting Diode; an electronic lamp, commonly used for various indicators in cameras (battery check, low-light warning, etc.)
  • Leica nipple
  • lens - a shaped piece of any transparent material (but in photography, usually glass or plastic) used to refract light, typically to focus an image. Also refers to an assembly of individual lenses (then called the lenses elements).
  • lens barrel - the tube that contains the lens elements.
  • lens cap - protective cover that clips over the front lens element when the lens is not in use.
  • lens coating - an anti-reflection coating applied to lenses, that reduces flare and increases contrast. All modern camera lenses are coated.
  • lens hood - a shade fitted around the lens to prevent light from outside the field of view falling on the lens surface.
  • lens mount - in a camera with interchangeable lenses, the mechanical arrangement to attach a lens, incorporating the mechanisms for communication between the lens focus control and the rangefinder (if present), and perhaps between the lens iris and the light meter. Camera makers have devised many different lens mounts, mostly incompatible with each other.
  • lens register - see flange focal distance
  • lens speed - refers to the largest aperture available on a lens: f/2 or wider might be considered fast.
  • light box - a tabletop device with a translucent, illuminated panel, for inspecting negatives and slides. By extension, the term has been used to refer to a format in which photographs are displayed on some websites including Flickr, in which the photographs are shown one at a time, surrounded by a black screen.
  • light leaks - various defects that can arise in a camera, that allow light to enter the camera body and spoil the film.
  • light meter - a device that measures the strength of light, used to determine the proper exposure settings for a scene. This may be a hand-held device, or built into the camera.
  • Light Value - an expression of the strength of the light in a single number. Each Light Value corresponds to a set of equivalent combinations of film speed, shutter speed and lens aperture. Related to, but not identical to, Exposure Value, which only summarises the camera settings.
  • light-value system - the use of Light Values in the design of camera controls; in many leaf shutters of about 1960, the shutter speed and aperture controls are linked, so that it is easy to switch between equivalent combinations, and these are labelled by Light Value.
  • live preview - a feature in digital cameras that allows a display screen to be used as a viewfinder.
  • lomography - a company which markets Lomo cameras (originally the LC-a) in the Americas, Europe and South-East Asia. The web-based shop presents itself as a 'movement' that promotes both Soviet-era Lomo cameras and models made specially for the Lomography company. Lomography encourages a "shoot from the hip" attitude, and a fondness for effects (deliberate light leaks, double exposure, pictures extending over the film perforations etc.)
  • long-roll camera - camera designed for motor-driven 100-foot film magazines; typical uses might includes school picture cameras or scientific recording
  • loupe - a small, mounted magnifying glass; sometimes fitted in cameras (e.g. TLRs) to magnify the focusing screen.
  • macro - photography with a very high degree of magnification in the camera (i.e. extreme close-up), the image on the film being life-size or bigger.
  • magazine camera - a plate (or sheet film ) camera typical of the early 20th century, with a chamber holding a number of plates in readiness, which can be switched quickly. See detective camera
  • McKeown's Price Guide to Antique & Classic Cameras - the leading English-language reference book and price guide for historical cameras
  • medium format - a film format larger than 35mm but smaller than large format. In modern film cameras, any format on 120 roll film. Also refers to digital photography using sensors larger than full-frame 35mm.
  • metering - measuring the strength of light for an exposure.
  • metering modes - choices a camera offers for whether, and which, of shutter speed and aperture are controlled automatically; or, the area of the scene to be metered
  • microprism - a focusing aid that may be built in to a focusing screen. See also split prism.
  • MILC - acronym for "Mirrorless Interchangeable Lens Camera"; applied to digital camera systems which do not use optical SLR viewfinders. See also EVIL.
  • mirror box - the section of an SLR camera housing the mirror. The need to keep this part of the camera empty to allow the mirror to move restricts the design of SLR cameras.
  • mirror lens (also catadioptric lens) - a lens using curved mirrors in place of one or more refractive glass lenses; this can dramatically reduce the physical length of a long focal-length lens by "folding" the light path.
  • mirror lockup - a feature on some SLRs that allows the reflex mirror to be locked in the up position to eliminate (mirror slap) vibration.
  • mirror slap - the vibration caused by the mirror in an SLR flipping out of the way before exposure.
  • monopod - a one-legged camera support.
  • MRC - Mid-Roll Change - a feature of APS film cameras that allows film roll removal and reinsertion without wasting exposures.
  • multicoated - see lens coating.
  • multiple exposure - see double exposure; deliberately or accidentally capturing more than one superimposed image on the same piece of film.

N to P

  • neutral density filter (ND filter)- a grey filter used to reduce the amount of light entering the lens, without being selective for any colour. This is used to allow a wide aperture to be used in bright light.
  • normal lens - the "normal" - or "standard" lens for any film format is simply one that gives an angle of view that looks normal. Conventionally, this is taken to be one with a focal length abut equal to the diagonal of the image frame, For full-frame 35mm, the diagonal is about 43 mm, but camera-makers have almost always supplied a 50 mm lens.
  • off-centre ball head
  • off shoe/camera flash - flash photography when the strobe is not mounted directly on the camera - can result in a more natural lighting effect, and avoid 'red-eye'.
  • ocular - an eyepiece lens.
  • optical axis - the straight line which passes through the centers of curvature of the lens surfaces.
  • orientation sensor - a sensor that detects orientation; e.g. horizontal or vertical.
  • orthochromatic - a type of black and white film with low sensitivity to orange and red light.
  • orthopanchromatic - a type of black and white film with equalized sensitivity to red, yellow and green light.
  • OEM - Original Equipment Manufacturer; refers to a company making items (or parts of them) for sale as another company's product. By extension, the maker may refer to those goods as 'OEM products'.
  • OTF - Off The Film; a light metering method carried out during exposure, measuring the light reflected off the film surface.
  • PAD - Pressure-Activated Diaphragm; the lens aperture stop-down mechanism on some lenses for Exakta and Miranda cameras, in which an arm protruding from the lens barrel positions a plunger over the shutter release button. Pressing the plunger both stops down the lens (to a preset aperture value) and then releases the shutter. It is a step toward automatic stop-down with these cameras.
  • panchromatic - sensitive to all colours of light.
  • panorama - an image of great width relative to its height, giving a wide angle of view. There are purpose-designed panoramic cameras; or a panoramic crop may be offered as an option on some normal cameras. Typically used for landscapes or large group of people.
  • parallax error - an effect in photography where the image seen in the viewfinder is not the same as that captured through the lens, due to the viewfinder being slightly apart from the lens (from 'parallel axis' error). It affects any camera other than a view camera or SLR, but is usually only significant with close subjects.
  • passport camera - a camera designed to take more than one similar image, for use in ID documents and cards.
  • pentamirror
  • pentaprism - a mirrored-prism element of some reflex viewfinders, that gives an upright, laterally-correct eye-level view. It is the angular lump on top of most 35mm SLR cameras.
  • photographica - any artefact connected to photography, widely considered worth collecting.
  • photography
  • photo-jumelle - a type of hand-camera popular in the early 20th century.
  • pincushion distortion - a form of lens distortion causing straight lines near the edges of the frame to curve inward. See also its opposite, barrel distortion.
  • prosumer - a term denoting mass-market "consumer" equipment with "professional" level features or specification
  • plate - photographic media on a rigid support, as used before flexible film (and used alongside it for many years). Plates were almost exclusively made from glass for most of their period; however, they have been made from other materials. Daguerreotypes were made on polished metal plates; ferrotype photography uses photographic emulsion on black-lacquered iron plates. In almost all cases, a plate holds a single photograph.
  • plate camera - a camera designed to use plates, but often also accepting sheet film, film-packs or roll-film.
  • point-and-shoot - a camera designed to eliminate the user's need to make focus and exposure settings.
  • polarizer - a filter that only allows light with a specific orientation to pass through it; may be used to eliminate reflections on some surfaces in the scene, and intensify some colours.
  • portrait format - rectangular pictures with the long edge oriented vertically.
  • portrait lens - a prime lens a little longer than a "standard" lens (in 35mm terms this is usually in the 85mm to 135mm range)
  • PQI - "print quality improvement," shooting information metadata recorded magnetically onto APS film, intended to help photofinishing equipment evaluate exposure when making prints.
  • pressure plate - a plate in the camera back that presses the film flat in the focal plane
  • prime lens - a lens of a single focal length, as distinct from a zoom lens
  • prismatic finder - the most common kind of viewfinder style found on SLRs. The viewing image is bounced through a path tracing a figure 4 through the prism turning the viewfinder image right ways up.
  • pseudo TLR - a camera whose appearance emulates a TLR, with a large, even full-frame reflex viewfinder, but which does not have the ground glass focusing of a true TLR.
  • pushing film - exposing film at a higher speed than its true speed; for example, setting the light meter to ISO 1600 when using Kodak Tri-X (true speed ISO 400) is 'pushing the film' by two stops. This is done to allow photography in low light; the film must then be 'push processed'.
  • push processing - giving a film extended development time to compensate for deliberate underexposure.

Q to R

  • QD - Quartz Date; an imprint function that records data onto the film emulsion; like the most basic data back.
  • QL - a designation by Canon for their film cameras of the 1970s with a "quick loading" feature.
  • RAW - an image file format directly from the sensor that has not been processed by a converter. It is sometimes referred to as a digital negative.
  • rangefinder (device) - a focusing aid, in which a device separate from the camera's lens is used to measure the distance to the subject. There is more than one type of RF; the most common overlays images from two viewpoints in the same eyepiece; one may be adjusted, and the distance to a given subject read off when the two images of the subject coincide. The RF may be coupled to the lens, so that adjusting the RF automatically sets the focus to correspond. The split prism of most SLR viewfinders is also a type of rangefinder.
  • rangefinder base - the distance between the two rangefinder windows on an RF camera (or between the RF and VF windows, if these are combined); it is generally thought that the further apart these are, the more precise the RF measurement can be.
  • rear curtain sync - in an SLR, firing of the flash at the moment before the rear curtain starts to close.
  • rebadge - equipment rebranded by original manufacturer for sale by another distributor.
  • rebrand - equipment with name or model modified by original manufacturer for sale by same manufacturer in different markets.
  • Reciprocity - the principle that one 'stop' of lens aperture or Light Value is equivalent to one of exposure time. At very low light intensity, this ceases to be true, so exposures must be longer than a simple calculation predicts. Film-maker's information includes the limit at which 'reciprocity failure' begins.
  • rectepanchromatic - a different name for the orthopanchromatic emulsion.
  • red eye - an unwanted effect achievable with a flash near the lens, common with compact cameras, where the eyes of any subject looking at the camera have a red dot in each pupil. This comes from the flash reflecting back from the eye's retina.
  • red window - a window covered in transparent red material in the back of a roll-film camera to show the frame numbers on the backing sheet of the film and show when to stop winding. Introduced by S.N. Turner's "Bull's-Eye" camera in 1892, bought-out by Eastman Kodak in 1895.
  • reflex viewfinder - any of several viewfinder designs in which the view is reflected in one or more mirrors. This may be simply to turn it through 90 degrees for chest- or waist-level viewing, as in a brilliant finder or Watson finder. However, in more modern cameras, it usually refers to a viewfinder in which the light from the camera's lens is reflected off a mirror and focused on a ground glass focusing screen for both focus and framing. In a TLR, the viewfinder uses a separate lens.
  • retrofocus - a lens design offering back focus larger than the optical focal length. This allows wide-angle lenses for rigid-bodied cameras: any lens shorter than about 35mm on a full-frame 35mm camera is a retrofocus design.
  • reversal processing - film development to give a positive image instead of a negative. The E-6 process for slide film is the most familiar modern example, but traditional black-and-white film can be reversed. Reversal processing usually involves development of the negative image, exposure to light, chemical removal of the developed negative image, and a second development which gives the positive image.
  • ring flash - a ring-shaped flash gun, designed to fit around the lens and give even lighting for close-ups.
  • Reisekamera - a type of portable view camera.
  • RGB - Red/Green/Blue - the additive primary colors, each representing about one third of the visible spectrum. Digital images can represent all colors by recording an R, G, and B brightness for each pixel.
  • roll film - in principle, any film that is prepared as a long strip and wound on spools, as distinct from sheet film; however, the term is often used to refer specifically to unperforated roll film (almost exclusively 120 film in the present day), as distinct from 35mm perforated film in cassettes.
  • RR lens - short for Rapid Rectilinear: a lens made of a symmetric pair of cemented doublets (also called Aplanat lens)

S to T

  • saturation - a measure of the intensity of a colour; reducing the saturation to zero gives a greyscale image.
  • seamless background - backdrop used in studio photography that does not have a hard transition between the floor and the wall; usually paper.
  • self-cocking shutter - a leaf shutter that is cocked automatically when the film is advanced. Focal-plane shutters have almost all done this for many years, so the term is not applied to them).
  • scanning - a digital photographic method which involves the sensor physically moving back and forth across the scene instead of having a sensor encompass the entire scene. This can be employed to create digital images of film frames, prints or other static subjects.
  • scientific cameras
  • scrim - a semi-transparent gauze or cloth screen used to create lighting effects
  • self-timer - a mechanism used to release the shutter after a short delay. This may be built into the shutter release, or may be an accessory that screws to the cable release socket. Also sometimes called a delayed-action control.
  • selenium meter - a type of light meter based on a photovoltaic cell, and therefore needing no battery.
  • shift lens
  • sharpness
  • shutter - the element of a camera that prevents light from reaching the plate, film or sensor until it is desired to open it, to make an exposure. The shutter usually consists of some arrangement of movable blinds or metal blades. Early cameras needed no shutter because photographic materials were so slow that a lens cap was a sufficiently precise control. Most digital cameras do not need a shutter because the sensitivity of the sensor can be switched on and off; nevertheless, some still have one.
  • shutter curtain - most focal plane shutters are composed of two curtains; a front and rear curtain.
  • shutter lag - see shutter latency.
  • shutter latency - the delay between the moment the shutter release is pressed and the moment the shutter actually opens.
  • shutter priority - a metering method which recommends an aperture based on a selected shutter speed; or the automatic-exposure mode in which such a meter value is automatically used.
  • shutter release - the control (usually a button or lever) that causes the shutter to open and close.
  • shutter speed - the time the shutter remains open, usually expressed as a fraction of a second.
  • slave flash
  • slow sync
  • SLR - Single-Lens Reflex; a popular kind of camera.
  • small format
  • snoot - a tube or cone attached to a lamp or flash unit to restrict the light, producing a spotlighting effect.
  • soft box - a diffuser built around the bulb of a photographic lamp, used to soften the light.
  • soft focus - a flattering technique often used in portrait photography that deliberately adds blur to a lens. The blur hides blemishes and smooths wrinkles.
  • soup - a slang term for film developer.
  • split-prism - a focus aid that may be built into a focusing screen. Typically this is arranged to give a central spot, split across the middle. The two parts of the image of any subject are shifted along the split-line, until that subject is in focus, when the half-images join. It is a form of rangefinder. See also micro-prism.
  • sports finder - a folding frame viewfinder.
  • spot meter - exposure meter that measures reflected light in a narrow angle of view.
  • sprocket holes - holes punched in a film to assist in moving the film through a camera or projector - particularly apparent on 35mm film.
  • spy camera
  • standard lens - See normal lens
  • stereo and stereophotography
  • stop down - to reduce the aperture of the lens - close down the iris diaphragm. The term can refer to the choice of an exposure with a small aperture (to increase depth of filed, or allow a long exposure time). It can also refer to the physical act of closing the aperture from wide open (for framing and metering) to the taking aperture, just before exposure: this is an automatic function in modern cameras, but earlier ones required manual stop-down.
  • strap lugs - fittings on a camera to allow attachment of a neck or wrist strap.
  • strobe
  • subminiature - a film format smaller than 24x36mm, or smaller than 18x24mm, depending on the authors
  • sunny-16 rule - a light metering guideline that says proper exposure on a sunny day is f/16 at a shutter speed that is the reciprocal of your film speed.
  • superpanchromatic - a black and white emulsion with increased sensitivity to red color, and some sensitivity beyond the visible red (i.e. into the infra-red range)
  • SVC - Still Video Camera; a CCD or CMOS video camera designed to take photo stills. Images are typically recorded on Video Floppy disks as analog scan lines. Superseded by digital cameras in early 1990s.
  • system camera
  • teleconverter - an add-on lens, usually inserted between the camera and the main lens, that increases its focal length.
  • telephoto - Strictly, a lens with back focus (the distance between the lens and film) significantly shorter than its focal length; the opposite of a retrofocus design. However, many people use the term simply to mean any lens with focal length much longer than the standard lens.
  • tilt and shift lens
  • TLR - Twin Lens Reflex.
  • trashcam - a slang term for a cheap, simple camera.
  • trigger advance
  • tripod - camera support with 3 legs.
  • TTL - Through The Lens, referring to viewfinding, metering, etc.
  • TTV - Through the Viewfinder photography

U to Z

  • umbrella - a light reflector or diffuser accessory.
  • webcam mode - allows a digital camera to be used as a video camera when connected to a computer.
  • VGA - a display standard with a resolution of 640x480 pixels.
  • view camera - a large format camera with a full-frame focusing screen at the rear. Almost always, this type of camera has 'movements' - rise, shift and tilt controls, that allow the geometric relationship between the film plane and the lens plane to be adjusted.
  • viewfinder - an element of almost all cameras; a component to let the user see what is in the camera's view while composing the picture.
  • viewfinder blackout - the time when the mirror in an SLR flips up to allow the film plane to be exposed during which the photographer cannot see anything through the viewfinder.
  • viewfinder camera - a camera whose viewfinder lacks rangefinder or reflex focusing, and is used for framing alone.
  • vignetting - dark corners in the image. These may be caused by objects close to the lens (the wrong hood for the lens, for example, or mounting too many filters), or bad camera design (so the internal parts of the camera block the light); however, many simple cameras vignette because they are equipped with lenses that simply don't cover the film area adequately. Some cameras are cult items (see lomography and Diana) because of their tendency to vignette, among other features.
  • waist-level finder - a viewfinder found on TLR and some SLR cameras in which the photographer looks down into a folding hood to view the image on a ground-glass focusing screen.
  • white balance
  • wide-angle lens - a lens giving a wide field of view, whose focal length is less than the "normal" length for the film format.
  • zoom lens - a lens that adjusts to cover a range of focal lengths.
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