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Lethbridge Digital Photography Glossary
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A glossary on digital photography technical and general for Lethbridge photo enthusiasts.
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Main Digital Photography Glossary | 2 | 3 | 4
 AberrationLens flaw that causes unsharp images. There are six types of aberrations: spherical, coma, astigmatism, curvature of field, distortion and chromatic.
AbsorptionOccurs when light is absorbed by a surface it hits and gets converted into heat waves.
Accessory shoeFitting to install accessories to a camera body; typically on top of the viewfinder, to attach a speedlight, a bubble level or any other accessory like a Nikon SC-17 or SC-19 flash cable.
AchromaticA lens system designed to reduce chromatic aberration, i.e. to render the same focal length for red and blue light wavelengths at the focal plane.
Action Finder (Action Viewfinder)An eye-level viewfinder allowing for complete view of the view field from a 2 to 3 inches distance; most convenient for fast moving objects and sports digital photography, as well as for detail copy work, making it less tiring.
AcutanceA measure of the sharpness with which the edge of an object can be depicted by a film or digital sensor.
AE (Auto Exposure)A system through which either the shutter speed or the lens aperture (semi-auto) or both (fully auto) are set automatically from the light meter. In high-end camera systems it is highly sophisticated; aided by a large data bank of different scenes to which the actual scene data is compared for highly improved accuracy, AE is virtually foolproof. Three types are available: Programmed Auto Exposure (P mode), where the camera sets both aperture and shutter speed; Aperture Priority AE, (A mode) when the user sets the aperture and the camera finds the most appropriate shutter speed; Shutter Priority AE (S mode), when the speed of the shutter is set by the user and the aperture by the camera.
AE LockA device to lock an Auto Exposure determined by the camera while the user recomposes.
AF (Autofocus)When applied to a lens, it is the ability of a lens to focus automatically on an object within its focusing sensors. AF Nikkor lenses were introduced in 1986. When on Auto bodies, there is no need to use the aperture ring in auto modes. They are AI-S lenses with a built-in CPU and motor for AF operation. When applied to a camera it means it is equipped with autofocus capability (a CAM module) to perform with an autofocus lens.
AF (Autofocus) Assist IlluminatorA device to provide additional illumination into a subject where there is total darkness or dim light or not enough contrast in it to perform Auto Focus. It can be set to automatically turn itself on when needed for fast operation.
AF-D lensNikkor lenses introduced in 1992. AF lenses with a CPU to relay distance information to the camera, most useful for ultra-precise TTL flash. Among the first were the 35-70mm f/2.8D AF and 80-200mm f/2.8D ED AF.
AF-I lens Auto Focusing Internal Nikkor lenses. Introduced in 1992, the AF coreless integrated motor is inside the lens itself and not on the camera body, making for faster autofocusing in large high-end telephoto lenses. The first were the 300mm f/2.8 and the 600mm f/4, both D ED IF AF-I. These lenses are the predecessors of the AF-S type versions.
AF LockUsed to prevent autofocus operation once the subject is in focus, useful when recomposing an image maintaining the previously selected plane in focus.
AF SensorThe sensor used to detect focus in cameras equipped with autofocus operation.
AF-S lens Only applicable to Nikkor lenses that came to market in 1996 and after. These lenses focus witth their own built-in auto focusing ultrasonic Silent Wave engine, instead of the focus drive motor in the camera, making for lightning speed focus acquisition. Most useful for fast moving subjects. The first were the 300mm f/2.8, 500mm f/4 and 600mm f/4, all D ED IF AF-S lenses. AF-S lenses with a "II" designation weight less and are generally smaller than their equivalent predecessors.
AI lens Manual Nikkor lenses, produced from 1977 until mid 80s, introduced Automatic Maximum Aperture Indexing, designed to let the camera body know what is the maximum aperture of the mounted lens for metering. Non-AI lenses coupled to the camera's meter through a system that required a pin on the camera to be mated to a slotted prong on the lens before the lens was mounted, then the aperture ring on the lens had to be turned from one extreme to the other to index the meter to the maximum aperture of the lens. AI eliminates this entire procedure because meter coupling and indexing occur automatically when the lens is mounted on the camera. Most AI lenses made until a few years ago were also supplied with the coupling prong so they would be compatible with either metering system. With all-black barrel, rubber focusing ring and multicoated elements.
AI'd lens Non-AI or pre-AI manual Nikkor lenses, modified to make them AI lenses. The AI'ing process usually only involves replacing the aperture ring with an AI aperture ring that allows for coupling to the "meter coupling lever" found on some early bodies. Camera enthusiasts have reported some services also adding the "lens speed indexing post" as a further step.
AI-P lens Manual AI-S Nikkor lenses with a CPU that sends the lens information to the camera body for metering, allowing all AF bodies with CPU contacts in the mount to use these lenses in Program mode. The latest is the ultra compact Nikkor 45mm f/2.8 P "pancake", made to celebrate the FM3A and proving Nikon's loyalty to film and manual body users. Some services can add the chip to AI-S lenses to convert them into AI-P.
AI-S lens Manual Nikkor lenses introduced in late 1981, early 1982, with Aperture Indexing Shutter system for refinded meter coupling. Smallest aperture is orange (if not, then the lens is either AI or pre-AI). Most of these lenses have extraordinary optics, like the legendary 105mm f/2.5 AI-S. The diaphragm action in an AI-S lens is compatible with certain cameras that allow the aperture to be controlled from the camera, as is required for P programmed and S shutter-priority automatic exposure control. All AF-Nikkor lenses, as well as most manual-focus Nikkor lenses made since 1982, are AI-S.
Ambient LightThe natural light in a scene.
Angle of ViewIt is the extent of the view taken in by a lens. It is determined by the focal length of a lens and film format. A “standard” 50mm lens for 35mm film has an angle of view equal to the diagonal of the film, which is 70° horizontally and 58° vertically. A 135mm "short telephoto" lens has a reduced angle of view of 29° horizontally and 23° vertically.
Angle of Flash coverageThe angle of coverage for even, uniform, edge-to-edge illumination by a speedlight. Usually expressed in terms of focal length. To accomplish such evenness it should always be of a focal length smaller or equal to that of the lens mounted on the camera body while using the flash. When the necessary angle of flash coverage cannot be accomplished through zooming of the head of the speedlight, it is increased with a built-in wide angle adapter that pulls out and flips down in front of the flash head, or with a dome diffuser.
ApertureThe adjustable opening in a camera lens that -like an eye's iris- controls the amount of light that reaches the film or digital sensor. The size of such aperture is called the f-stop, like f/2.8
Aperture PriorityAperture Priority Auto Exposure, (A mode) when the user sets the aperture and the auto camera sets the most appropriate shutter speed. Most used mode as it is the appropriate for accurate depth of field control. Since the exposure decision is not entirely left to the camera's onboard computer, this is referred to as a semi-auto mode.
ApochromaticRefers to lenses designed to correct for chromatic (color) aberrations. Usually used in telephoto lenses that have large maximum apertures.
ArchivalThe ability of a material, including some printing papers and inks as well as digital compact and video discs, to last for many years.
ASAAbbreviation for American Standards Association (Now ANSI). In digital photography, Used in conjunction with a number, e.g., ASA 400, refers to film or sensor "speed" or sensitivity to light. The higher the number, the more sensitive the film/sensor, allowing for faster shutter speeds and/or smaller f/stops. The ASA scale has been replaced by the one from ISO (International Organization for Standardization), the scale numbers remain the same; e.g. ASA 100 = ISO 100 (See ISO for further explanation)
Aspherical (ASP) Not a continuous curve. Refers to non-spherical elements in lenses designed to compensate for distortion by having different curves on individual elements. Nikon introduced the first photographic lens with aspherical lens elements in 1968. Allows for more compact wide angle lenses, lighter and better performing than others with only spherical elements. When applied to Nikkor lenses the term implies excellent performance with absence of coma and other aberrations, even at their widest aperture.
AstigmatismCauses light rays from an off-axis point to form images at different positions.
Auto CameraA camera that can adjust the aperture and shutter speed automatically using data from its built-in exposure meter.
Auto FlashElectronic speedlight that automatically adjusts flash duration based on flash-to-subject distance relayed to it by the camera body.
Auto LensA lens with an automatic aperture diaphragm that can be kept wide open, at its widest aperture, until the shutter is released, regardless of the aperture setting for the exposure. Such a lens makes for a brighter viewfinder view and eases focusing with through-the-lens cameras. When the shutter is released, the aperture automatically stops down to its pre-set opening so that proper exposure is made, and instantaneously returns to its widest aperture. This lenses also allow for metering when wide open with a compatible camera with metering capability.
Available LightExisting light surrounding a subject; whether natural or artificial, but not added by the digital photographer, like with strobes or speedlights.
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B (Bulb)Setting for (long) time exposures beyond the normal shutter speeds. Under this setting the shutter will remain open for as long as the shutter release button is depressed.
BackdropThe background in a studio, usually made of cloth or paper.
BackgroundThe area behind a subject.
BacklightingLight coming from behind the digital photo subject. Can cause underexposure of the main subject with auto exposure systems. Situation lending itself to the use of fill-flash and/or spot metering.
BellowsAccordion-like device mounted on cameras that allows the lens to move towards or away from the film/sensor-plane for greater magnification than with the lens alone. Usually employed for close-up or macro work. Camera bellows are the PB-3, PB-4, PB-5 and the latest model PB-6 which can be extended further for higher magnification with the PB-6E extension bellows.
BitmapAn array of binary data representing a pixel by pixel (bit-mapped) image or display; also the image or display itself.
Bounce LightLight bounced into a reflective surface (a wall, a ceiling, a studio umbrella, a card) to illuminate a subject with softer light, reducing harsh shadows. The color of the reflective surface will determine the color of the light bounced into the subject.
BokeJapanese term, pronounced BO-KEH in English, used to describe the out of focus quality of a lens. Noun derived from the active verb "bokasu" which means to befog, to gradate, to render opaque, to smudge or render out of focus. It is usually the out of focus portions of the picture which distinguish the "look and feel" or "signature" of different types of lenses. The ideal boke for portraiture is a soft edged rounded blur with the brighter part towards the center of the blur disk.
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Classic boke is that of legendary lenses like the 105mm f/2.5 (click on image above) and 85mm f/1.4 Nikkor.
BokehSee "Boke" immediately above.
BlurUnsharp. Caused by excessive movement of the camera, a zoom lens or the subject. Also, excessive UV (ultra-violet) light that causes a bluish haze and loss of definition on distance objects, especially on B&W film. Blur is often intentional in creative digital photography to convey the feeling of motion.
BracketDevice that attaches to the camera tripod socket for accessories or to separate a speedlight from the camera, out of the hot shoe. Most useful for shadow control and red-eye elimination as it increases the angle between that of the flash beam axis and that of the lens.
BracketingPractice of making additional images varying exposure to insure accurate exposure of a given subject; e.g., additionally exposing "one stop under" and "one stop over." Automated feature in recent camera models.
Brightness(1) The amount of light reflected by a surface.
(2) The intensity or amount of light emitted by a light source.
(3) The luminance of a color.
BufferTemporary memory area that stores data before it is written into a permanent area. In digital cameras, the memory where images are stored before they are written to the memory card.
BulbShutter speed setting where the shutter stays open as long as the shutter release is depressed. Usually indicated by a B on the shutter speed selector.
BurningSelectively darkening part of areas in a digital photo while in traditional printing or with an image editing program.
BSNo, it does not refer to the advertising of other camera brands. It refers to the British System developed by the British Institute of Standards, for photographic film speed or sensitivity; using the same scale as the ASA system, now both replaced by the ISO.
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Cable ReleaseA flexible cable device for releasing the shutter. Usually used for slow shutter speeds when the camera must remain absolutely still. A must for ultra sharp images.
CartridgeA light-proof film container, usually made of metal. It is often called "magazine" or "cassette".
CatchlightThe reflection of a light source in the eyes of a subject. It makes for more pleasing portraits. Usually provided by the use of fill-flash.
CCD (Charged Coupled Device)A semiconductor device that is used especially as an optical sensor and that stores charge and transfers it sequentially to an amplifier and detector; also called CCD, used in digital cameras to capture an image.
CC (Color Compensating) FilterEnables fine adjustments to color tone or color density in color digital photography. Most CC filters are made of gel and come in six colors: C (Cyan), M (Magenta), Y (Yellow), B (Blue), G (Green) and R (red).
CD-RCD-Recordable. A compact disc that holds either 650 or 700 MB of digital information, including digital photos. Creating one is commonly referred to as burning a CD. A CD-R disc can only be written to once, and is an ideal storage medium for original digital photos.
CD-RWCD-Rewritable. A compact disc that holds either 650 or 700 MB of digital information, including digital photos, like the CD-R, except that a CD-RW disc can be written and erased many times. Best suited for backup tasks, but not for long term storage of original digital photos.
C-W (Center-Weighted) Fill-FlashFill-Flash technique using Center-Weighted metering, recommended for ambient light control for a subject in the center of the frame. One of the many pioneering technology advances, whereby the burst request made to the speedlight is based on a balanced exposure between the ambient light surrounding the subject and the light provided by the flash without making the latter noticeable. Precise ambient exposure control is achieved by pointing the meter into different brightness areas and making the selection of choice, or through camera and/or flash EV compensation.
C-W (Center-Weighted) MeteringA center-biased metering method. In high-end cameras, the bias is variable. In the F5 for example, through Custom Setting 14 the circle of highest meter sensitivity (75%) can be changed from 12mm to 8, 15 or 20mm diameter. Before advanced Matrix Metering was introduced in 1988 on the N8008/F801, much improved over that on the FA, all cameras with meter had a Center-Weighted one.
Chromatic AberrationCaused by the differences in refraction of the colored rays of the spectrum. It is "axial" when light rays pass through a lens cause the lens to focus at different points, depending on the light wavelength. It is "lateral" or "transverse" when the magnification varies depending on the light wavelength. It creates blur.
CibachromeUnique color printing system, directly from color transparencies, not from an internegative, developed by Ciba-Geigy Photochemie of Switzerland and Ilford of the UK in the early 60s. With stunning sharpness, color intensity, clean whites, and critical accuracy to the original slide, Cibachrome prints made on a dimensionally stable tri-acetate polyester base, not paper; are archival, will not fade, discolor or deteriorate for a very long time. When Ilford was acquired by International Paper in 1989, Ciba-Geigy required the name changed. So it is now officially called Ilfochrome, but its fans keep calling it Cibachrome.
Circle of ConfusionThe circle of confusion has nothing to do with other camera brand users. It is the largest on-film/sensor circle that you can see as a well defined point on an 8×10 print when viewed at from a "normal" viewing distance of 2 to 3 feet. Anything larger is seen as a small circle, not a point and is therefore perceived as out of focus. For 35mm film format the diameter of such point or circle is 0.02501mm, commonly rounded to 0.03mm for hyperfocal distance computations. For APS-C (DX) digital cameras sensors, the CoC is 0.020
Circular PolarizerA digital photographic filter designed to eliminate reflections from glass and water, including water in foliage, to intensify the color of the sky and color saturation in general. A circular polarizer does not interfere with the AF or the Metering systems of auto cameras like a linear polarizer would typically do.
Close-upA digital photo or video or movie shot taken at close range filling the frame. Magnification ratios of a close-up typically vary from 1:10 to 1:1 (life-size).
Close-up Attachment LensA convenient and economical way to enter close-up digital photography. Attached to the front of a lens its magnification ratio ability is increased by shortening the focusing distance. 0, 1, 2, 3T, 4T for 52mm diameter lenses; and 5T & 6T for 62mm, are the Camera close-up lenses available. Also called close-up "filters".
CRC (Close Range Correction System)One of the many pioneering efforts that provides superior picture quality at close focusing distances and increases the focusing range of a lens. Through “Floating Element” designs -wherein each lens group moves independently to achieve focusing- CRC enables selected Nikkor lenses to provide comparable performance at both very near and very far focusing distances. For fisheye and wide angle lenses, CRC allows for most interesting perspectives. A most impressive example of a lens with this feature is the AF-S 17-35mm f/2.8D ED IF Zoom Nikkor.
CMYKAcronym for Cyan (process Blue), Magenta (process Red), Yellow and Black, the primary colors of ink used in professional printing process to which Black is added for enhancement or for true Black. Not to be confused with the primary colors of light which are Red, Green and Blue (RGB).
ColorThe appearance of objects (or light sources) described in terms of a person's perception of their hue and lightness (or brightness) and saturation.
Color TemperatureThe temperature at which a blackbody emits radiant energy competent to evoke a color the same as that evoked by radiant energy from a given source (as a lamp). Measured in Kelvin degrees (K), important to digital photographers to understand how light changes and film records it and to filter it to fit the film in use. In digital photography the light conversions/adjustments can be made via software. Average noon daylight has a color temperature of 5500K. A common tungsten house light bulb has a color temperature of 2800K. Tungsten studio lamps 3200K and digital photo lamps or digital photofloods 3400K.
Color (Temperature) Conversion FilterConverts the color temperature of the light source as it goes through it to fit the film in use. For example, a dark blue B12 filter makes it possible to use daylight balanced film with tungsten studio lamps, changing the light temperature from 3200K to 5500K. In digital photography the light color conversion filters effect can be added via software.
ComaAberration where light rays pass through an off-axis point causing the lens to focus at different points causing blur.
Compact CameraA Point-and-Shoot camera (P&S). Convenient in size, smaller than a SLR camera, lacking advanced features.
CompactFlash™ CardTrademark name for one type of digital camera's re-usable memory card on which images taken by the camera are stored. Available in a wide range of storage capacity and recording speeds.
Continuous Servo AFUsed to allow the camera to continue focusing as long as the shutter release is slightly pressed. This allows an AF camera to take a picture even if the picture is not in focus. Used for making images of fast moving subjects. AF mode "C".
Contrast Control FilterFilters used in black and white digital photography to emphasize contrast in various degrees. There are six major types: Y (Yellow), Y/G (Yellow/Green), G (Green), O (Orange), R (Red) and the not so frequently used B (Blue), for portraits, to strengthen skin tones and bring out more detail in faces. Contrast filters improve the separation of tones. The deeper colored the filter the more pronounced the contrast effect.
ContrastThe apparent difference in brightness between lightest and darkest areas of an image. Usually refers to the gradation between black and white. Fewer gray values are described as "high contrast." Many shades of gray is low contrast.
Continuous Servo AFEspecially useful AF mode when focus tracking fast moving subjects. Under this mode you can fire at any time. As long as the shutter is half-depressed the AF module will keep a subject in focus and make calculations as to its position at the moment of firing.
Convertible LensA multi-piece lens. The pieces assemble or disassemble to form different focal lengths.
CopyrightA form of protection provided by the laws of the United States (title 17, U.S. Code), and other countries, to the authors of "original works of authorship," including literary, dramatic, musical, artistic, and certain other intellectual works. This protection is available to both published and unpublished works. Some favorites and new arrivals in today's competitive high-tech digital photo world by user ratings. | | |
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