Glossary of Basic Photo Terms

A

AMBIENT LIGHT: The light in the scene, as opposed to the light provided by the photographer with flash, photofloods, etc.

ANGLE OF VIEW: The maximum angle a lens covers in the field. Measured in degrees, and qualified by terms such as wide-angle, normal, and telephoto. A wide angle lens has a wider angle of view than a telephoto lens. A 135mm lens on a 35mm SLR covers an 18-degree angle of view; a 28mm lens covers a 75-degree angle of view.

APERTURE: The opening of a lens, the size of which is controlled by a diaphragm. The term is commonly used to designate f-stops, such as f/4, f/5.6 etc., which are actually arrived at by dividing the focal length of the lens by the diameter of the aperture. Thus, f/11 on a 110mm focal length lens means the opening is 10mm. The wider the opening, the lower the f-number, the more light is let through the lens. Each step in aperture represents a halving or doubling of light. Thus, f/8 allows in half as much light as f/5.6, and twice as much light as f/11.

APERTURE PRIORITY: An autoexposure mode in which the aperture is selected and the exposure system selects the appropriate shutter speed for a correct exposure. Sometimes referred to as AV or simply A on exposure mode controls.

ARCHIVAL: Long-lasting. In processing, those procedures that help insure stability of the image. Also, storage materials that will not damage photographic film and paper, or computer-produced prints.

ARTIFICIAL LIGHT: Any light not directly produced by the sun. Can be tungsten, flash, household bulbs, sodium vapor street lamps, etc. In many cases, the color produced by artificial light is deficient in the blue end of the spectrum, thus daylight-balanced color films will record the light as being warm/red/amber. Tungsten-balanced slide films, or color-balancing filters over the lens will generally correct this problem. In some cases, color print film can be re-balanced when prints are made.

AUTOEXPOSURE: A method of exposure where aperture and shutter speed settings are first read, then set, by the camera's exposure system. Various autoexposure modes allow for customization or biasing the readings.

AUTOEXPOSURE LOCK: A push-button, switch, or lever that locks in exposure after the initial reading has been made, regardless of a change in camera position or light conditions after the lock is activated. Release of the lock button returns the exposure system to normal. Useful for making highlight or shadow readings of select portions of the frame, and an essential feature for critical exposure control with automated cameras.

AUTOFOCUS: A method of focusing where focusing distances are set automatically. In 35mm SLRs, a passive phase detection system that compares contrast and edge of subjects within the confines of the autofocus brackets in the viewfinder and automatically sets focusing distance on the lens. Autofocusing motors may be in the camera body or the lens itself. Active IR (infrared) autofocusing systems may also be in 35mm SLRs in the form of beams in dedicated autofocus flash units, or, in a few models, built into the camera itself. Commonly found in amateur lens/shutter cameras. These beams are emitted from the camera or flash, bounce off the subject, then return and set focusing range.

AUXILIARY LENS: An add-on optical device that alters the focal length of the prime lens for close-up, telephoto, or other special effects photography. The close-up devices, for example, usually comes in +1, +2, and +3 powers; the higher the number the greater the magnification.

AVAILABLE LIGHT: The light that's normal in a scene, although the term is generally used when the light level is low. Available light shooting usually involves fast film, low shutter speeds and apertures, and/or the use of a tripod.

AVERAGING: In light metering, where the light is read from most of the viewfinder frame then averaged to yield an overall, standard exposure for the scene. This setup works fine in normal lighting conditions, but may need some additional input when light is flat or contrasty.

B
B or BULB: A shutter setting that indicates that the shutter will remain open for as long as the shutter release is pressed. The term originated with the rubber air shutter bulbs used to operate shutters in the old days. B settings are generally used in nighttime and time/motion study photography.

BACKGROUND: The portion of a scene that sits behind the main, foreground subject. The background can be made sharp or unsharp through the use of selective focusing techniques and depth of field manipulation.

BACKLIGHTING: From camera position, light that comes from behind the subject. Usually, a backlit main subject will be underexposed unless the metering system is set to read selectively off the subject, or exposure on a center-weighted meter is compensated accordingly. See also fill-flash. Extreme backlighting can be exploited to create silhouettes.

BLACK-AND-WHITE: A photographic film or paper used to create monochrome images. Though we think of black and white mainly in terms of a gray scale, prints can have a wide variety of subtle tones, from blue- to brown-black. Though the overwhelming majority of photography today is shot and printed in color, black-and-white has attracted a fiercely loyal and dedicated group of photographers.

BLUR: Unsharpness because of the movement of the camera or subject during exposure. Blur can be used for many creative effects. In computer imaging, the use of Blur controls to selectively soften parts of the image.

BOUNCE LIGHT: In flash photography, directing the burst of light from the flash so it literally bounces off a ceiling, wall, or other surface before it illuminates the subject. This method of flash is often preferred because it softens the overall light and eliminates the harsh, frontal effect of an on-camera, straightforward flash.

BRACKET: Making exposures above and below the "normal" exposure, or overriding the exposure suggested by the camera's autoexposure system. Useful as a fail-safe method for getting "correct" exposure in difficult lighting conditions. Bracketing can also be used to make subtle changes in the nuance of tone and light in any scene. With slide film, bracketing will show an effect in 1/3 stop increments; with negative film a full stop of bracketing is advised.

BRIGHTNESS: The luminance of objects. The brightness of any area of the subject is dependent on how much light falls on it and how reflective it is. Brightness range is the relationship we perceive between the light and dark subjects in a scene. Brightness contrast is a judgment of the relative measure of that range, such as high, low, or normal. Brightness values are sometimes referred to as EV (exposure values), a combination of aperture and shutter speed. Brightness values in the scene are translated to tonal values on film.

BURNING-IN: In darkroom work, giving additional exposure to a portion of a print made from a negative to add density and tonal information. Often used to balance tones in contrasty scenes. The same term is used in digital darkroom programs.

BURNT-OUT: Jargon that refers to loss of details in the highlight portion of a scene due to overexposure. With slide film, it might mean that no image detail has been recorded on the film, or that highlights show no texture or tonal information. A highly burnt-out, or burnt-up slide may show clear film base in overexposed areas.

C
C-41: The current process for all standard color negative films.

CABLE RELEASE: A flexible encased wire attached to a threaded metal coupler that screws into the shutter release button on the camera. When one end of the wire is depressed with a plunger the other end activates the shutter. Electronic cable releases for all-electronic cameras work with electrical impulses rather than mechanical plungers. Usually, the two types are incompatible. Useful for long exposures to avoid camera shake and for remote release of the shutter.

CAMERA: A light-tight box containing light sensitive film or sensor that is used to make images. Today's cameras incorporate microprocessors and sophisticated exposure systems; in a sense, the instrument itself mirrors the age, just as the pictures it makes reflect the world in which we live.

CCD: For charged couple device; the sensor used by most digital cameras, and in flatbed scanners.

CD-ROM: A compact disc that can store a large amount of information. The CD-ROM drive reads that information. CD-R is a recordable CD for home and studio use. The Photo CD and CD-R are write once, read many times discs; a CD-RW is a CD that can be written over, if desired.

CENTER-WEIGHTED: In a metering scheme, an exposure system that takes most of its information from the center portion of the frame. Most center-weighted systems also take additional readings from the surround, but weight the reading towards the center.

CHIP: Common name for sensor, actually a silicon wafer with circuit paths etched or printed in layers.

CLOSE DOWN: Jargon that refers to making a photograph with less exposure than previously used. With apertures, using a narrower apertures; with shutter speed, using a faster shutter speed. For example, going from f/8 to f/11 means closing down the lens by one stop.

CLOSE-UP: Any photograph made from a distance that is generally closer than our normal viewing distance. Close-up pictures are often startling in the detail they reveal.

COLOR BALANCE: The color balance of a film refers to the kind of light under which it will faithfully render color without the need for filters. Most films are daylight-balanced, which means that in daylight, or with a daylight balanced flash, colors will be true. A tungsten-balanced film can be used under certain types of artificial light to give true colors without filters or special printing techniques.

COLOR COUPLER: A colorless substance contained in color film emulsions that, when exposed to chemical developing baths forms the color dyes that make up part of the layers of processed color films.

COLOR NEGATIVE FILM: A film that forms a photographic image in which light tones are rendered dark (and vice versa) and colors are reproduced as their complements (such as blue being recorded as yellow); all of reversed tones and colors are then reversed again in printing to form a positive record. Color negatives have an orange mask (an aid to printing), so may be difficult to "read". Color negative films come in a range of speeds (ISO), or sensitivities to light. Each speed of film has its uses and characteristics that can be matched to particular shooting needs.

COLOR TEMPERATURE: The Kelvin scale, which is defined in degrees. It is used as a standard for balancing daylight films (approximately 5500 degrees K) and tungsten-balanced film (approximately 3200 degrees K.) Color conditions that vary from the standards will create a color cast in photographs made with these films, e.g., a daylight film used with artificial light will record with an amber cast; a tungsten film used outdoors will record with a blue cast.

COMPOSITION: The arrangement of subject matter, graphic elements, tones, and light in a scene. Can be harmonious or discordant, depending on the photographer, his or her mood, and the subject at hand. There are no set rules, just suggestions; successful compositions are ones that best express particular feelings about the subject or scene.

CONTACT PRINT: A print made the same size as the negative.

CONTRAST: The relationship between the lightest and darkest areas in a scene and/or photograph. A small difference means low contrast; a great difference high contrast. High contrast scenes usually cause the most exposure problems; however, their difficulty can mean they hold the potential for more expression. Though contrast is often linked with scene brightness, there can be low contrast in a bright scene and high contrast in dim light. Contrast can also describe attributes of color, composition, and inherent qualities of film.

CONTRAST GRADE: In black and white printing, an indication of the contrast rendition the paper will yield. #0 and #1 are low contrast; #4 and #5 are high contrast. The "normal" contrast grade is #2.

CONVERSION FILTER: A filter that gives allows daylight film to record color faithfully in artificial light or, conversely, for tungsten-balanced film in daylight. For example, orange conversion filters are used when exposing tungsten-balanced films in daylight, bluish filters for daylight-balanced films in tungsten light. Most useful with slide films, as color negative imbalances can usually be corrected when prints are made.

CORRECT EXPOSURE: The combination of aperture and shutter speed that yields a full-toned negative or slide that yields the best possible tonal representation of the scene onto film or sensor. The constants in an exposure calculation are the speed of the film and the brightness of the scene; the variables are the aperture and shutter speed.

CROP: To select a portion of the full-frame image as the final picture. Cropping is done in the darkroom or computer environment by the photographer, or by an appointed surrogate in a commercial photo lab.

D
DAYLIGHT-BALANCED: A film that will reproduce colors faithfully when exposed in daylight. The film can also be used with flash, as properly made flash or strobes yield daylight-balanced light.

DARKROOM: The work space for developing and printing photographic film and making prints.

DEDICATED FLASH: A flash that coordinates with the camera's exposure, and sometimes focusing systems. Dedicated flashes may, among other things, automatically pick up the loaded film's ISO, set the camera shutter speed to X-sync, and "tell" the camera when its ready to fire. Flashes dedicated to autofocusing cameras may also vary their angle of flash throw according to the lens in use (even with zoom lenses), and contain autofocus beams that aid focusing in very dim light or even total darkness. For outdoor work, dedicated flashes may provide totally automatic fill-flash exposure. In short, a dedicated flash can be make flash photography as simple as automated natural light photography.

DENSITY: In general terms, the measure of the light-gathering power of silver or dye deposits in film. Also, the buildup of silver that creates the image in film and paper. A "dense" negative or slide is more opaque than a "thin" one. There is an ideal density for film, one that yields good prints or slides; too little density usually means that the film was underexposed (or underdeveloped), too much means its been overexposed (or overdeveloped).

DEPTH OF FIELD: The zone, or range of distances within a scene that will record on film as sharp. Depth of field is influenced by the focal length of the lens in use, the f-number setting on the lens, and the distance from the camera to the subject. It can be shallow or deep, and can be totally controlled by the photographer. It is one of the most creative and profound effects available to photographers.

DEPTH OF FIELD PREVIEW BUTTON: A switch, button, or electronic push-button that allows for preview of the depth of field of the set aperture in the viewfinder. During composition the lens is wide open, thus the depth of field in the viewfinder is always that of the maximum aperture of the lens. It is very useful for critical selective focus shots; although some rightfully consider it no more than an approximation, others feel that an SLR lacking a depth of field preview function is greatly diminished as a creative tool.

DEVELOPING: A series of chemical and physical actions done in a commercial lab or the home darkroom that converts light-struck film to an image that can be viewed directly or printed; making prints from negatives.

DIGITAL: Information used by the computer, represented by numbers. The buzzword for any capture device that converts photons to electrons. The use of that information to store, manipulate, transmit or output images in a computer environment. As opposed to analog.

DIGITAL CAMERA: A filmless camera that converts light energy to digital information and stores that information in a buffer or directly onto a removable memory card.

DIGITAL DARKROOM: The computer and image editing and manipulation programs.

DIGITIZE: The conversion of analog (film, print) information to digital form by use of a scanner, digital sensor or camera.

DISTORTION: Any changing of line, form, or even light by photographic materials, such as lenses, films, or filters. Though most designers do all they can to eliminate distortion from lenses, most photographers take the "if you can't beat 'em, join 'em" approach and exploit it wherever they find it; they use distortion as part of their visual expression.

DODGING: In conventional or digital printing and image manipulation, the selective reduction of density in certain areas of the scene.

DX-CODING: A system of film cassette coding and in-camera pins that informs the camera's exposure system that a specific speed and exposure length film is loaded. Most modern 35mm cameras have this feature.

E
E-6: The current developing process for the majority of today's color slide films; the term also refers to films developed by this process, such as E-6 type films.

ELECTRONIC FLASH: Known as a flash gun, strobe, or speedlight, it consists of a gas-filled tube that is fired by an electrical charge. It can be mounted directly on the camera hot shoe (which links the shutter firing to the flash firing), or on a bracket or stand and be connected to the camera via a sync cord.

EMULSION: Used alternately with film, but refers to the coating on the acetate film base. Emulsions consist of light-sensitive silver salts, color couplers, filters, and other layers that work together to both protect and form the actual photographic image on film.

ENLARGEMENT: Making a print from a negative or slide; generally, making a print larger than standard size, such as an 8x10-inch or bigger "blowup".

EXPOSURE: The amount of light that enters the lens and strikes the film or sensor. Exposures are broken down into aperture, which is the diameter of the opening of the lens, and shutter speed, which is the amount of time the light strikes the film. Thus, exposure is a combination of the intensity and duration of light.

EXPOSURE LATITUDE: The range of exposures in which a satisfactory image will be produced on a particular type of film or sensor.

EXPOSURE METERS: Light reading instruments that yield signals that are translated to f-stops and shutter speeds. Reflected-light meters read light reflected off the subject; incident meters reads light falling upon the subject. All in-camera meters are of the reflected-light type.

F-NUMBERS: A series of numbers designating the apertures, or openings at which a lens is set. The higher the number, the narrower the aperture. For example, f/16 is narrower (by one stop) than f/11--it lets in half as much light. An f-number range might be f/2.8, f/4, f/5.6, f/8, f/11...To find the next aperture in a narrowing series, multiply by 1.4. F-numbers are arrived at by dividing the diameter of the opening into the focal length of the lens, thus a 10mm diameter opening on a 110mm lens is f/11. Alternately used with f-stops.

F
FAST: A term used to describe a film with a relatively high light sensitivity, a lens with a relatively wide maximum aperture, or a shutter speed, such as 1/1000 second, that will freeze quick action.

FILL-IN FLASH: Flash used outdoors, generally to balance a subject that is backlit. Can also be used to control excessive contrast, add light to shadows, or brighten colors on an overcast day.

FILTERS: Any transparent accessory added to the light path that alters the character of the passing light. With film, filters can alter contrast, color rendition, or the character of the light itself (diffusion, diffraction, etc.) In printing, variable contrast filters are used to evoke different contrast grades from variable contrast black and white paper. In computer imaging software, a set of instructions that shape or alter the image information.

FILM: A compilation of light sensitive silver salts, color couplers (in color film), and other materials suspended in an emulsion and coated on an acetate base. The storehouse of our visions, nightmares, and dreams.

FINE GRAIN: Usually found in slow speed films, a fine-grained image is one where the medium of light capture and storage, the silver halide grain, is virtually invisible in the print or slide. With high, or coarse grain films (usually very high speed films) the texture of the grain becomes part of the physical reality, or weave of the image.

FIXER: The third step in black and white print and film processing; the bath removes unexposed silver halides.

FLARE: In lenses, internal reflections and/or stray light that can cause fogging or light streak marks on film. In general, zoom lenses have more potential for flare than fixed-focal-length lenses; in either case a screw-on lens hood helps reduce the problem.

FLAT: Low in contrast, usually caused by underexposure or underdevelopment of film. Flat light shows no change in brightness value throughout the entire scene.

FOCAL LENGTH: The distance from the lens to the film plane or sensor that focuses light at infinity. The length, expressed in millimeters, is more useful as an indication of the angle of view of a particular lens. A shorter focal length lens, such as a 28mm, offers a wider angle of view than a longer one, such as 100mm.

FOCUS: Causing light to form a point, or sharp image on the image sensor or film.

FOCUS LOCK: In autofocus camera systems, a button, lever, or push-button control that locks focus at a particular distance setting, often used when the main subject is off to the side of the frame or not covered by the autofocus brackets in the viewfinder.

FORMAT: The size of the film, thus the camera that uses such film. Large format refers to 4x5 inches and larger; medium format uses 120 or 220 (6cm wide) film. Smaller formats include 35mm and 24mm. In computer imaging, the file structure, or "language" that can be understood by the device.

FRAME: The outer borders of a picture, or its ratio of the height to width. The individual image on a roll of film. Also, to compose a picture.

G
GRAIN: The appearance or echoes of the silver crystals in film in the final negative or positive image. The larger the area of the grain in the film emulsion, the more sensitive the film is to light; the more sensitive it is to light the "faster" it is. Larger grains are manifest in the image as mottled or salt-and-pepper clumps of light and dark tones, usually apparent in very fast films on visual inspection, in slow films upon extreme magnification. Grain is most easily seen as non-uniform density in areas sharing the same tone (such as a gray sky.)

GRAY SCALE: The range of tones, from bright white to pitch black that can be reproduced in a film and print.

GROUND GLASS: A specially prepared glass used as the focusing screen in cameras.

GUIDE NUMBER: A number that relates the output of electronic flash when used with a particular speed film. The higher the guide number, the more the light output. Guide numbers, or GN serve as a way to calculate aperture when shooting flash in manual exposure mode. Dividing distance into guide number gives the aperture: For example, a flash with a guide number of 56 (with ISO 100 film) would give a correct exposure at 10 feet with an aperture of f/5.6. With the state of today's automatic exposure flashes, guide numbers today are mostly useful for comparing the relative power of one flash to another.

H
HIGH CONTRAST: A scene where the range between the brightest and darkest areas is extreme, or is such that it may cause exposure problems. A film that renders scenes in high-contrast fashion. The absence of middle grays.

HIGHLIGHTS: The brightest parts of a scene that yield texture or image information. With slide film, it's best to bias expose for the highlights, as overexposure of bright areas will yield a burnt-out look. A spectral highlight is pure light and will print as "paper" white.

HOT SHOE: The mount on the camera body in which electronic flashes are secured. Hot shoes usually contain electrical contact points that signal the flash to discharge when the shutter is fired.

HYPERFOCAL DISTANCE: The nearest point in the scene which is in focus when the lens is focused at infinity. This distance changes according to the focal length of the lens and the aperture at which it is set. Setting a lens at its hyperfocal distance maximizes the depth of field when infinity must be kept sharp.

I
INCIDENT LIGHT/INCIDENT METER: The light that falls on a subject, rather than that which is reflected off it. Many handheld meters are of the incident light reading type. Incident readings are made from the subject with the meter pointed back at the camera.

INFINITY: On a camera lens distance scale, the distance greater than the last finite number, and beyond.

INFRARED FILM: Film which is highly sensitive to red/near infrared radiation. A red filter should be used to get the best effect with this film.

ISO: A prefix on film speed ratings that stands for International Standards Organization, the group that standardizes, among other things, the figures that define the relative speed of films.

L
LATENT IMAGE: The invisible image that is formed when the silver halide compounds in film are struck by light. Upon development, this image, or series of light and dark tones, is made manifest.

LENS: A combination of shaped glasses and air spaces set in a specific arrangement within a barrel. Within the lens is a diaphragm that can be opened and closed to allow in specific amounts of light. This is controlled manually by a ring on the outside of the lens barrel, or electronically via pins in the coupling ring that mounts the lens to the camera. Lenses have two primary functions: one is to focus light with as little distortion or aberration as possible on to film or sensor. Focusing is accomplished by changing the relationship of the elements in the lens to the film plane. The other function is to control the amount of light hitting the film by use of its aperture. Autofocusing lenses may contain small motors for racking the lens back and forth in response to changes in focus.

LENS COATING: A thin layer of transparent material applied to glass surfaces in a lens to control light reflections, reduce flare, and increase image contrast.

M
MACRO: Another word for close-up photography, but specifically referring to taking pictures at or near life-size. Can be defined as a ratio; for example, a 1:2 ratio means that the image on film is half-life-size of the object in nature.

MANUAL: An exposure "mode" where the exposure system recommends a setting that is then made by the photographer by selecting aperture and shutter speeds manually. The booklet one doesn't read before using a piece of equipment.

MAXIMUM APERTURE: The widest opening, or f-stop a lens affords. An f/1.4 lens is referred to as fast because it has a relatively wide maximum aperture; an f/4.5 lens is slow because of its relatively narrow maximum aperture. Fast lenses come in handy for hand held low-light photography.

MINIMUM APERTURE: The smallest opening a lens affords. Generally, wide angle lenses have a minimum aperture of f/22; normal lenses of f/16; and telephoto lenses of f/32.

MIRROR LENS: A lens where the light path is bent and reflected internally to increase the focal length of the lens; a simplified system that is usually less expensive than conventional super-telephoto (300mm and up) lenses.

MODE: A way of doing things. Exposure modes are pre-programmed, user-selectable ways of controlling the readings from the exposure system to meet certain subject or picture conditions. These include aperture-priority mode, shutter-priority mode, program-depth mode, etc. Autofocusing modes allow a choice of how the camera/lens will go about autofocusing.

MOUNT: In lenses, a specific set of pins and cams that couple a particular lens to a particular camera body. For photographs, a way of protecting the photograph and giving it a rigid support.

N
NEGATIVE: An image where the tones (recorded brightness values) and, with color film, the colors are reverse of those in the scene. When printed, the negative becomes "positive."

O
OVEREXPOSURE: In exposure, when too much lighting strikes the film for a proper rendition of the scene. Minor overexposure may cause a loss of details or texture in the scene highlights; severe overexposure will cause a serious deterioration of picture quality in color and black and white print film, and a complete loss of picture information with slide films.

OVERRIDES: Making adjustments or intervening to change the camera's autoexposure system reading. Some overrides include exposure compensation and changing ISO ratings.

P
PANNING: A shooting technique where the subject is followed during exposure; generally done with a slow shutter speed.

PHOTOGRAPHY: Writing with light.

POLARIZING FILTER: A filter that transmits light waves vibrating in one direction, used to deepen blue sky with color film, tame contrast in very bright scenes, and to ``see'' through reflective surfaces, such as water and glass.

POSITIVE: Another word for slide, as is "transparency". Also, a print from a negative.

PREVISUALIZATION: A thought process that helps a photographer "see" what the photograph will look like on film, and/or a print, done as the picture is being composed.

PROGRAM EXPOSURE MODE: A preset arrangement of aperture and shutter speed that is programmed into the exposure system of a camera to respond to a certain level of brightness when the camera is loaded with a certain speed of film. Custom program modes include Program Wide ( also referred to as Program Depth) chooses a higher aperture at the expense of shutter speed in the exposure equation; Program Tele (or Action) chooses a higher shutter speed at the expense of aperture. Program Normal, or simply Program, is totally camera-controlled and makes all the decisions about aperture and shutter speed settings.

PUSHING, PUSH-PROCESSING: An exposure/processing technique in which the effective speed of the film is raised, coupled with an increase in developing time. In actuality, it is deliberate underexposure of the film with extended developing time that increases density mainly in the highlight areas. Pushing raises the contrast and increases grain, but it can be used effectively for creative and corrective shooting under dim lighting conditions.

R
REFLECTED LIGHT METER: A meter that reads light reflected from the subject. All in-camera meters are of this type.

REFLEX VIEWING SYSTEM: A system of mirrors in an SLR that makes the scene right-reading in the camera's eye-level viewfinder.

S
SATURATION: In color, a vividness, or intensity. Some films have more inherent color saturation than others. Saturation can be slightly increased by moderate film pushes, or by slight underexposure of certain slide films. Saturation can be increased in color negative film by moderate overexposure.

SELECTIVE FOCUS: The creative use of focus. Focus can be set so that one plane or subject in a crowded scene emerges, or for sharpness near to far in a scene that covers miles. Selective focus is achieved through the use of various focal length lenses, by altering camera to subject distance, and by changing f-stop settings.

SHADOW: In photography, usually defined as those details or image information contained in the darker areas of a scene.

SHARPNESS: The perception that a picture, or parts of a picture are in focus. Also, the rendition of edges or tonal borders.

SHUTTER: In a focal plane shutter, a set of curtains travels past the film gate and allows light to strike the film within a set period of time. A leaf shutter is located within the lens itself.

SHUTTER RELEASE BUTTON: The button that releases the shutter and ``fires'' the camera. Many shutter release buttons have two stages-slight pressure actuates the meter or autofocus system (or both), further pressure fires the shutter.

SHUTTER PRIORITY: An autoexposure mode where the shutter speed is user-selected and the exposure system chooses an appropriate aperture for correct exposure.

SHUTTER SPEED: An element of exposure; the duration of time in which light is allowed to strike the film.

SILVER HALIDE: A compound containing silver, the crystals of which are the light-sensitive element in film.

SINGLE-LENS-REFLEX: Or SLR. A type of camera that has a movable mirror behind the lens and a ground glass for viewing the image. Film sits behind the mirror assembly, which swings out of the way when an exposure is made. "Single-lens" distinguishes it from TLR, or twin-lens-reflex cameras, where separate lenses are used for viewing and taking.

SLIDE: A positive image on a transparent film base, used for projection viewing, printing, or photomechanical reproduction.

SLOW: A term used to describe a film with a relatively low sensitivity to light, a lens with a fairly narrow maximum aperture, or a shutter speed at or below 1/30 second.

SOFT FOCUS: A picture, or an area in a picture that is left slightly out-of-focus for effect, or a lens or filter that diffuses light and "softens" the overall scene.

SPECIAL EFFECTS: Any technique, lens, filter, accessory, computer effect, use of film, etc. that converts or distorts the "reality" of nature in a picture. Special effects can be sublime or ridiculous, depending on the subtlety with which they're used.

SPEED: With a shutter, the duration of time in which light strikes the film. With film, the sensitivity to light. With a lens, the maximum aperture. All can be described as either fast, medium, or slow speed.

SPOT METERING: Taking an exposure reading from a very select portion of the frame. Cameras with built-in spot metering indicate this portion with a circular ring in the viewfinder screen. Some spot meters have coverage as broad as 8-degrees (this might also be called selective field metering) or, with a handheld spotmeter, as narrow as 1-degree. Many incident meters now have spot metering options. Spot metering is always a reflected light reading, thus is subject to that type of meter's failures.

STOP: A relative measure of light that can be used to describe an aperture or shutter speed, although it is more commonly used with aperture settings. A difference of one stop indicates half or double the amount of light. To stop down means to narrow the aperture; to open up means to expand it.

SYCHRONIZATION,or SYNC: The timing of the firing of the flash to coincide with the opening of the shutter so that the maximum light from that flash records on the film.

T
TELEPHOTO: A generic name for a lens with a focal length of higher than 50mm and an angle of view less than 45 degrees (with 35mm format.) A moderate telephoto might be in the 80mm class; a medium telephoto in the 135mm grouping; while a long-range, or extreme telephoto might have a 300mm or higher focal length.

TIME EXPOSURE: A long exposure, usually not handheld, for recording scenes at night or in very dim rooms.

TRIPOD: A three-legged device with a platform or head for attaching the camera, used to steady the camera during exposure. It is most useful for exposures longer than 1/30 second, or when a constant framing must be maintained throughout a series of shots.

TTL: Or Through-The-Lens metering. A flash autoexposure mode that measures light as it reflects off the film plane is referred to as OTF-TTL (off-the-film plane TTL.)

TUNGSTEN-BALANCED: Film that it balanced to reproduce colors faithfully when exposed under artificial tungsten light sources. Also, the lamps that emit that light.

U
UNDEREXPOSURE: Failure to expose correctly because not enough light has struck the film or sensor to faithfully render the color and brightness values. Underexposed pictures are dark; the more the underexposure the darker they become. Color also suffers when film is underexposed, although a slight amount of underexposure can be used to increase color saturation in certain color slide films.

UV FILTER: A clear, colorless filter that stops most ultraviolet rays from recording on film. Handy for shooting distant landscape shots, as it eliminates the bluish haze that might otherwise veil the picture.

V
VARIABLE CONTRAST: A type of black and white printing paper that when exposed under different color light yields different printing contrast grades.

VIEWFINDER: The viewing screen in an SLR on which composition takes place; viewfinders may also contain various guides to exposure, focus, and flash-readiness. In all senses, the control panel from work is done.

W
WASHED OUT: Jargon for seriously overexposed slides, or overexposed highlight areas within slides and prints. It's as if the colors have been diluted to the extent that all pigments have been "washed out."

WARM TONE: The look or mood of a print or slide that tends toward the amber, or yellow/red. In black and white, a brown or sepia-toned print, or a brown-black printing paper.

WIDE-ANGLE LENS: A lens that offers a wide angle of view, usually in the 35 to 24mm focal length range. Ultra-wide-angle lenses range from 20mm to 8mm. Wide-angle lenses also allow use of very deep zones of focus.

Z
ZONE FOCUSING: A way to focus that utilizes the depth of field scale rather than the actual distance from camera to subject. Zone focusing is most useful for candid, street photography.

ZONE SYSTEM: An exposure calculating system based upon previsualizing the scene as a set of tonal variations, and exposing and developing to maximum that tonal set.

ZOOM LENS: A lens on which the focal length can be varied, as opposed to a fixed focal length lens. Zooms come in various focal length ranges, such as 35 to 105mm; all focal lengths including and within this range can be utilized.