Digital Dictionary

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Aberration – An optical defect in a lens. A phenomenon resulting from the failure of a lens or mirror, to produce a good image.

AC Adapter – "Mains adapter". Device that enables the connection of the digital camera, to the mains electricity supply.

Active Autofocus – Cameras with active autofocus systems determine the correct focusing distance by projecting beams of energy, usually infrared or light energy out to the subject.

Acutance – A measure of sharpness of a photographic image. It is not the same as "Resolving Power". The resolution of a photographic image depends as much on the resolving power of the lens, as on the acutance of the CCD or film emulsion.

AE Lock – The ability to hold the current exposure settings, and allow you to point the camera elsewhere before capturing the image. This is usually accomplished by half-pressing the shutter button, and keeping it at that position until you're ready to capture the image.

Algorithm – A set of processing or working instructions that, because of their high precision, can be carried out independently by a mechanical or electronic device. Algorithms are, for example, the set rules for addition and subtraction etc. However, they are also the instructions that are established in a programming language. Algorithms simply allow the computer to solve particular problems. In image editing, algorithms are used to alter images, e.g.  3D Cubic Algorithm.

Aliasing – "Jaggies". Pixel-shaped curves on the diagonal edges of objects. This can sometimes occur since all graphics consist of individual pixels. Anti-aliasing reduces this unwelcome effect by recalculating the contrast values of the neighboring pixels and matching them up with each other.

Ambient Light – In the context of flash photography, whatever light is currently illuminating the scene is available light. Flash photography involves adding supplemental light to this scene using flash units.

Anaglyph – An old method of producing three–dimensional images by using two slightly offset photographs, one typically colored red and one blue. The photographs are viewed through either a viewer or through disposable spectacles with appropriately tinted color gels. The result fools the brain's sense of depth perception, leading to a sort of three dimensional effect. Today, however, the rare 3D movies which are made (usually for world fairs and the like) are typically done using polarized lenses and glasses.

Analog – Opposite of digital. Analog data merges continuously into each other without clearly defined steps (e.g. the colors of a rainbow are not obviously separable from one another).

Aperture – Mechanism behind the lens that controls the amount of light entering the camera. The aperture not only influences picture brightness but also regulates depth of focus. Most cameras are equipped with an iris aperture that can be freely adjusted or set according to pre-selected values.

Aperture Priority (Av) – Allows the user to select the desired aperture, and the camera automatically chooses the correct shutter speed for exposure.

Artifact(ing) – Misinterpreted information from a JPEG or compressed image. Color faults or line faults that visibly impact the image negatively.

Artificial Light – Photographically speaking, any light source which is not the sun or something illuminated by sunlight.

Aspherical Lens – A lens surface which is not a portion of a sphere in cross section. Aspherical lenses are used by lens designers to minimize certain types of aberration, particularly spherical aberration. Sometimes indicated by ASPH or AL.

Autoexposure (AE) – Automatic exposure.

Autofocus (AF) – Automatic focus adjustment. There are basically two main AF methods: the focus detecting method, or passive auto focus usually employs a CCD and works by evaluating the amount of contrast or the phase difference in a scene. Distance metering or active autofocus utilizes an (infrared) light emitter and receiver in a triangular surveying system. Alternatively, the camera uses ultrasound (sonar) and measures the time taken for the sound signal to return. This data is converted by a microprocessor into information about distance and thereby enables the automatic focusing of the lens.

Auto ISO – The camera chooses the proper ISO value for correct exposure, according to available light, aperture, and shutter speed.

Average Metering – "Matrix". A special exposure metering technique, that measures the average light intensity across the entire frame. Average metering attempts to balance out the entire exposure, by sampling many points within the frame.



Backlighting – Any light coming from behind the subject. A typical example is a photo of a person taken with the camera facing towards the sun. Backlighting is particularly difficult for automatic exposure systems in cameras to deal with, since the range of light tends to be so extreme, and lenses tend to flare.

Ball Head – A mounting head used on tripods or monopods, consisting of a metal or plastic ball in a socket. The ball is held into place by friction, usually with an adjustable collar. Ball heads allow the camera to be pointed easily in any direction. Therefore; are more convenient for field work where uneven surfaces are encountered, than the pan-tilt head.

Barrel Distortion – A common form of lens flaw or aberration, curvilinear distortion, in which parallel lines towards the edge of the image area appear to bow outwards, like the shape of a traditional wooden barrel. Also known as negative distortion. Computer monitors are susceptible to the same problem, albeit for very different underlying technical reasons.

Bitmap (BMP) – A representational form for a digital image, in which each bit in the computer's memory, corresponds to one dot on the screen or printer.

Bit Depth – Color Depth, e.g. 16 bit (high color), 24 bit, and 32 bit (true color).

Blocked Up – A highlight area which is overexposed will have little or no detail. This area is said to be blocked up.

Blown Out – An overexposed image or portion of an image, in which highlights are indistinguishable patches of white are said to be "blown out." This can be a deliberate effect, particularly for high-key photography, or it can simply be a mistake caused by incorrect metering.

Blooming – The opposite of noise; an image error that has been more or less eradicated in the newer digital cameras. It describes the "overflow" of electrical charges between the individual sensors on a CCD element.

Boken – A term borrowed from the Japanese, pronounced with short vowels. (ie: more like French pronunciation – bo-ké – versus long English diphthongs – bow-kay). Essentially bokeh, which is Japanese for blurring, refers to the quality of out of focus areas of a picture. Bokeh can be important for portraiture – you want out of focus areas behind the subject to be smooth and as non-distracting as possible. Highly patterned or sharp-edged areas don't look as good.

Bounce Light – A softer light than regular flash or flood. Produced by reflecting light from a ceiling, wall, or other surface.

Bracketing Exposures – A method of insuring perfect exposure by taking (usually) three exposures: 1 @ the meter reading,  2 @ the meter reading plus one stop,  3 @ the meter reading minus one stop.

Burning – Increases the exposure to areas of the print that the photographer wishes to be darker. By shading other areas of the image, while increasing exposure to the desired area.
(2) Also called "Burning In".

Burned Up – Badly overexposed.



Cable Release – A cable that enables the photographer to trigger a camera shutter, without touching the camera itself.

CAF – Acronym for "Continuous Auto Focus".

Catch Lights – Reflections, generally in the subject's eyes when portraits are being made, from the light sources used for illumination.

Candid Photography – Spontaneous photographs taken outside a posed studio situation; often when the subject is unaware of the camera's presence.

CCD – "Charge Coupled Device". A light sensitive semiconductor that converts received light into voltage according to the level of brightness. It is used as a chip or line sensor in digital cameras and scanners.

CD-Rom – "Compact-Disc-Read-Only-Memory". A "read only" CD-ROM can hold up to approximately 700 MB of programs, pictures, text, or other data.

Center Weighted Metering – This method of exposure metering, is often used for subjects that occupy the majority of the frame; and that have an even contrast distribution. Center weighted metering concentrates on about 75% of the center frame, and averages out the balance of the exposure.

Chromatic Aberration – A common lens flaw which results in loss of sharpness, and also in color fringing, white light having colored halos (commonly green or purple) around the edges.

Circle Of Confusion – The diameter of a circle, created by a lens photographing a point source of light at infinity. The smaller the circle of confusion, the sharper the image or print will be. Recognizing that real lenses do not focus all rays perfectly under even the best of conditions, the circle of confusion of a lens is a characterization of its optical spot.
(2) The term circle of least confusion is often used for the smallest optical spot a lens can make, for example by picking a best focus position that makes a good compromise between the varying effective focal lengths of different lens zones, due to spherical or other aberrations.

Clear Filter – Also known as a window glass filter or optical flats, are completely transparent, and (ideally) perform no filtering of incoming light at all. The only use of a clear filter, is to protect the front of a lens.

Cloning – To make an exact duplicate of digital image data. In digital systems it is possible to copy part of an image onto another.

CMOS – "Complementary Metal Oxide Semiconductor" – Another imaging system used by digicams. It is not as popular as CCD, but the future promises us even better digicams based on CMOS sensors due to the lower amount of power consumption, versus the typical CCD device.

CMYK – "Cyan, Magenta, Yellow, and Key/Black". These are the printer colors used to create color prints (subtractive color mixing).

Color Cast – An unwanted tint of one color in an image caused by a disproportionate amount of cyan, magenta, and yellow. This can occur due to an input or output device.

Color Depth – This refers to the maximum number of colors that can be recorded by digital cameras, and scanners or can be displayed by graphics cards. A true color representation can be achieved at a color depth of 8 bits per primary color, that is a 24 bit color depth. In this case, 256 bits are available for one pixel. With a RGB signal, this value is then multiplied by a factor of three so that a total of 256 x 256 x 256 = 16,777,216 colors can be displayed. High-end scanners, graphic cards, etc; provide a minimum color depth of 24 bits.

Color Gamut – Is a complete subset of colors. Normally it refers to the subset of colors that could be represented or displayed by e.g. a monitor or any other output device. You can also see it as the sum of the colors found in an image.
Changing colors also changes the gamut of that image. For example: a printer is capable of printing colors that could not be displayed on the monitor or printed on some other printer. This comes form different techniques used to show the color.

Color Management – The calibration of all peripheral devices that feature in the production of color images (monitors, scanners, color printers etc). For example, by using a color management system, the data from a scanner is converted into values for a standard color range. The data is then arranged so that the printer can produce good color prints.

Color Noise – The incorrect reproduction of color on an image (e.g.  color dots on an area which is supposed to be pure white).

Color Temperature – Describes the spectral energy distribution, and thereby the color quality of a light source. The temperature of a color is given in Kelvin (K). It is important to choose the correct temperature, so that a subject can be photographed in its true colors. The spectrum that can be seen by the human eye lies between approx. 2,790 K, and 11,000 K. The international norm for average sunlight is 5,500 K.

Collage – A term used to designate a montage effect, made by pasting up a composite photograph from portions cut from other photographs.

Composition (Visual Arts) – The plan, placement or arrangement of the elements of art in a work. In general, good pictures result from careful attention to some basic elements of composition, together with appropriate lighting and an interesting subject. There is, however, no "right" way to take a picture. Three photographers recording the same scene may create equally appealing photographs, with entirely different compositions.
Never allow yourself, to believe you have to follow a strict set of rules. Self expression is just as important in photography, as in other art forms. To restrict yourself, is to limit your creativity, and loose your identity – just taking another indistinguishable so-so picture.

Compression – Data may be compressed to reduce storage (memory) space or transmission times (equals reducing the amount of data). Well-known compression standards include JPEG, and MPEG.

Convolution – In optics, many kinds of "blur" are described by convolutions. A shadow (e.g.  the shadow on the table when you hold your hand between the table and a light source) is the convolution of the shape of the light source that is casting the shadow, and the object whose shadow is being cast. An out-of-focus photograph is the convolution of the sharp image with the shape of the iris diaphragm. The photographic term for this is bokeh (bo-ké).

Converter/lens Converter – Lens extension that increases, or shortens the focal length. (e.g.  Macro-converter, tele-converter, wide-angle converter).

Cool – Color which is blue in tint or tone. Light with a high color temperature is said to be cool light, confusingly enough.

Cropping – The process of cutting some of the image area to remove some undesirable portion, or to improve composition. All good photo editors like Adobe Photoshop have a tool for this function.



Dark Frame – A noise reduction process whereby a camera takes a second exposure of a black frame after the camera takes a long exposure (1/2-second or longer) image. The image "noise" is easily identified in the black frame shot, and is then electronically removed from the actual image. This helps, reduce the amount of hot pixels that normally show up in long exposure shots from digital cameras.

DCF – "Design Rule for Camera File System". An industry standard for saving digital images. This not only determines the file type, but also sets the rule for naming the folder, and file structure. It allows the conversion of uncompressed TIFF files, into compressed JPEG files. This JPEG file is of the Exif type, and can contain camera information such as the date.

Deconvolution – Unwanted convolution is an inherent problem in transferring analog information. For instance, all of the following can be modeled as a convolution: image blurring in a shaky camera, echoes in long distance telephone calls, the finite bandwidth of analog sensors and electronics, etc. Deconvolution is the process of filtering a signal to compensate for an undesired convolution. The goal of deconvolution is to recreate the signal as it existed before the convolution took place. Focus Magic, is one such image sharpening program that uses this process, and provides second to none performance.

Dedicated Flash – Describes an electronic flash, that is made to be used only with a specific model of camera. Canon, Nikon, Olympus and other cameras have specific electrical contacts in the hot shoe to pass TTL-metering, and AF range data to/from the flash unit. You can not use a dedicated Canon flash on a Nikon camera for example.

Depth Of field (DOF) – In optics , particularly as relates to film and photography , the depth of field is the distance in front of, and beyond the subject that appears to be in focus.
The DOF is determined by the subject distance, the lens focal length , and the lens f-number (relative aperture). Except at close-up distances, DOF is approximately determined by the subject magnification and the lens f-number. For a given f-number, increasing the magnification, either by moving closer to the subject or using a lens of greater focal length, decreases the DOF; decreasing magnification increases DOF. For a given subject magnification, increasing the f-number (decreasing the aperture diameter) increases the DOF; decreasing f-number (increasing the aperture diameter) decreases DOF.

Depth Of Focus – Is a lens concept that measures the tolerance of placement of the image plane (the film/ccd plane in a camera) in relation to the lens. While the phrase depth of focus was historically used, and is sometimes still used, to mean depth of field, in modern times it is more often reserved for the image-side depth. Depth of field is a measurement of depth of acceptable sharpness in the object space, or subject space. Depth of focus, however, is a measurement of how much distance exists behind the lens wherein the film/ccd plane will remain sharply in focus . It can be viewed as the flip side of depth of field, occurring on the opposite side of the lens.
Where depth of field often can be measured in macroscopic units such as meters and feet , depth of focus is typically measured in microscopic units such as fractions of a millimeter or thousandths of an inch . Since the measurement indicates the tolerance of the film/ccd displacement within the camera, depth of focus is sometimes referred to as "lens-to-film/ccd tolerance."

Diffraction – An optical effect which can limit the total resolution of your photography; no matter how many megapixels your camera may have. Ordinarily light travels in straight lines through uniform air, however it begins to disperse or "diffract" when squeezed through a small hole (such as your camera's aperture). This effect is normally negligible, but increases for very small apertures. Since photographers pursuing better sharpness use smaller apertures to achieve a greater depth of field , at some aperture the softening effects of diffraction offset any gain in sharpness due to better depth of field.
When this occurs your camera optics are said to have become "diffraction limited". Knowing this limit can help you to avoid any subsequent softening, and the unnecessarily long exposure time or high ISO speed required for such a small aperture. Depending on lens design this condition appears around F-16, but can appear in some lens at lower apertures (e.g.  small sensor digital cameras at F-8).

Digital – Opposite of analog. Digital information is made up of a limited number of gradations (e.g.  256 colors, 8 bit). The change from one digital element to the next is always "step by step" and not continuous.

Digital ESP – "Digital Electro-Selective Pattern". The employment of a selective multi zone metering system ensures an optimal exposure even in difficult light conditions.

Digital Zoom – Digital zoom crops your image, and magnifies the result of the cropping. This magnification process is called interpolation. To make the cropped area bigger, digital zoom makes up, or interpolates pixels to add to the image, which may give less than satisfactory results. A judicious use of digital zoom, may sometimes yield images that are of quite acceptable quality. So, use with caution. What is important when comparing digital cameras is the optical zoom. Digital zoom can always be achieved later in an image editing software, such as Photoshop, so should not really be a determining factor when choosing a digital camera.

Diode – Photodiode (photosite).

Diopter Adjustment – The adjustment of the viewfinder to the photographer's eyesight.

DNG – "Digital NeGative" – Opened RAW format created by Adobe to avoid the proliferation of proprietary formats. DNG is based on the TIFF format, it can include a thumbnail and/or real size JPG preview (not necessarily up-to-date). Some brands, like PENTAX, offer the possibility to capture the picture in their PEF format or in DNG without quality loss.
A section in the DNG format is still allocated to proprietary data. Another one permits to keep the original RAW data as backup. The presence and the management of these sections depends on the camera and the image manipulation software used.

Dodging – A process of shading a part of an image that decreases the exposure for areas of the print, that the photographer wishes to be lighter.

Dot Pitch – Used with monitors, it indicates the distance between individual dots. The smaller the distance between dots, the sharper the image. Good monitors usually have a dot pitch of between 0.25 and 0.27 mm.

DPI – dots per inch (1 inch equals approx. 2.54 cm). A measuring unit in printing to describe the geometric resolution of an image.

DPOF – "Digital Print Order Format". A format introduced by the photo industry that enables images stored on SmartMedia cards, to be accessed directly by certain printers and copiers, as well as allowing the more simple professional treatment by photo labs.

Drop Shadow – A graphic art effect designed to simulate the shadow cast by three dimensional shapes.

DSLR – Digital SLR (Digital Single Lens Reflex) camera. Interchangeable lens digital camera. Manufacturers include Canon, Fuji, Kodak, Nikon, Olympus, Pentax, Sigma, and others.

Dynamic Range – Is the range of input or output that a device can process, without overflow or distortion. Clipping of highlights, and shadows in point & shoot digital cameras, show the limited dynamic range. Generally 4 stops plus, and minus, from the center of the determined exposure; referred to as 8 stops of lateral exposure. 35mm slide film has about 10 stops of lateral exposure, and some DSLR models claim around 12 or more.



Edge Light – In portraiture, a light placed behind the subject to give a halo effect, and illuminate the edges of the head and shoulders.

Effective Aperture – The diameter of a lens measured through the front lens element. Sometimes this may be larger than the actual lens opining in the lens diaphragm, because of the converging action of the front element of the lens.

EV – Exposure Value, a very complex thing but in the digicam world, it usually means the ability to override the auto exposure system to lighten or darken an image.

EVF – Acronym for Electronic Viewfinder. Electronic viewfinder's show you the same view that the lens sees. In fact, what you see when you look through an electronic viewfinder is identical to what you see on the camera's LCD screen

Exif – "Exchangeable image format". A standard for image files created with digital cameras, and other input devices. Exif files can contain either uncompressed TIFF or compressed JPEG images, and may contain many comment fields of various types.

Exposure Bracketing – the camera automatically takes a series of 3 or 5 pictures, and slightly varies the EV for each frame. This insures that at least one of the pictures, will be as close to perfectly exposed as possible.

Exposure Correction/Compensation (EV) – Conscious deviation from the value ascertained by the light meter. The change can be made manually (under and over expose by changing the shutter speed, f-stop combination) or through the programmed auto exposure control, EV (exposure value). Which allows up to 2 stops plus, or minus exposure; in 1/2 or 1/3 steps from the cameras automatic light meter setting.
For example, let's say you're taking a photograph of a white dog sitting on the snow. Most camera auto-exposure systems will try to get everything looking 18% grey, and will thus under-expose the picture. You could apply a stop or two additional exposure compensation (EV), above the camera's program to correctly expose the dog.

Exposure Time – The length of time for which the shutter is open.



Feathering Light – Letting only the soft outside rim of light, hit the object.

Filter – 1. A transparent, mostly colored sheet of glass or plastic, that can be placed in front of a lens to create a certain effect. 2. An option in an image editing program, that enables certain adjustments to the picture, (e.g. color and brightness or foreshortening).

Fill Flash – Using the flash to lighten shadow areas, or just to provide more overall illumination in situations where you normally wouldn't use the flash. Outdoors in bright light, you get very stark shadows underneath of people's noses, chins and etc. Toggle the flash setting to "forced on" or "fill" and the flash will now fire on every shot. It also gives your human subjects that special little sparkle in their eyes.

Fill-In Light – In portraiture or other photography by artificial light. Fill-in lights are used to fill in the dark shadow portions of the subject, so that some detail will be recorded.

Firmware – Software contained in ROM (read only memory), that manages the camera's operation.

Fixed Focus – A lens that is preset to a given focus distance, it has no autofocus mechanism, set to give the camera the maximum depth of field.

Fixed Focal Length – A term that describes a non-zoom lens, it is fixed at a given focal length and is not variable.

Flash – Produces a large amount of light for a brief moment to illuminate the subject. Modern flashes work with glass discharge tubes. Computerized camera flashes can measure, and automatically control their intensity by means of a sensor directed at the subject.

Flash Duration – The camera's flash synchronization, ensures the flash is emitted while the shutter is open.

Flash ROM – A type of memory storage that can retain information, even after the power has been switched off. Unlike conventional ROM, the contents of a Flash-ROM can be deleted, and rewritten with the help of a pre-programmed electrical current. Therefore, a Flash-ROM is a combination of RAM (random access memory) and ROM (read only memory).

F Stop – Also "f number." The relative aperture of a lens, or the numbers used to indicate lens apertures – the amount of light that a lens lets in. These numbers are a relative number, and are equivalent to the focal length of the lens divided by the size of the lens aperture.
For example, if you were to take a 50mm lens with a 6.25mm diameter aperture you'd have a lens set to f/8. Generally, each increase or decrease in f stop value either doubles or halves the aperture size. Since f stop values are relative to the focal length, each camera lens should let the same amount of light through at the same f stop value, regardless of focal length.

Flash Synchronization – Co-ordinates the opening of the camera's shutter with the time, and duration of the flash. Some cameras allow you to synchronize flash at the beginning, or end of the shutter travel ("sync1" and "sync2" respectively).

Focus Assist – Some cameras employ a visible or invisible (infrared) lamp, to illuminate the subject so the autofocus can work in low light, or total darkness.

Focal Length – The distance between the center of the lens system, and the film or CCD sensor, (i.e.) where the image is in focus. Normal focal length gives an image impression roughly corresponding to that of the human eye, (about 50 mm in conventional film cameras, and about 7 mm in digital cameras with 1/3" CCD).



Gamma – A measure of the amount of contrast found in an image, according to the properties of a gradation curve. High contrast has high gamma, and low contrast low gamma.

Gamut – The range of colors that are available in an image or output process. It is generally used in describing the capabilities of a printer to reproduce colors faithfully and vibrantly – i.e. "The xxxxx printer has a wide color gamut."

GB – Acronym for "Gigabyte".

Gigabyte – 1 Gigabyte equals, 1,024 Megabytes.

GPS – "Global Positioning System". The GPS receiver uses satellites to let you determine the exact longitude, latitude, and height above sea level anywhere on earth.

Gray Scale – A scale of shades ranging from white to black. Devices that can only display data in black and white, translate color differences into various shades of grey.



Hand-held Exposure Meter – External exposure meter.

HDR – "High Dynamic Range". Popularly used to refer to the process of tone mapping together with bracketed exposures (usually three) of normal digital images, giving the end result a high, often exaggerated dynamic range. However the resulting image quality, is less then that of any of the single images.

Hi Color – Describes an image having at least 32,000 colors.

Highlight – The lightest areas of the image or page.

High Key – Images the contain mostly light areas with no, or few shadows, bordering on over exposure. Contrast in a high key image is also usually very even, or flat.

Histogram – A bar graph analysis tool that can be used to identify contrast, and dynamic range of an image. Histograms are found in the more advanced digicams, and software programs (graphic editors) used to manipulate digital images. The histogram shows a scale of 0 – 255 (left to right), with 0 being black, and 255 being white.

Horgaths's Line – A double curve in the form of the letter s, frequently employed in photographic composition; its sometimes called the line of beauty or "S" curve.

HQ-Resolution – "High Quality Resolution". Description for high digital photo quality.

HTML – "HyperText Markup Language", a file format used in the World Wide Web, (e.g. this page).

Hyperfocal Distance – The distance from the camera to the nearest object in focus, when the lens is focused to infinity. The smaller the aperture of the lens, the shorter the hyperfocal distance will be, and consequently, the greater the depth of field.



Image Compression – In order to store digital pictures economically, the image data is compressed. However, compression often causes a reduction in picture quality.

Image editing Software – Describes software which allows the user to view and alter digital images. A commonly used image editing program is Adobe Photoshop.

Image Plane – The area inside the camera where the object is focused clearly. The image plane can be compared to the film plane in analog cameras; the difference being that the film is replaced by the CCD chip.

Incident Light Meter – The meter reads the amount of light illuminating the subject, not light reflected from the subject, so the meter ignores the subject and background characteristics. As with a reflected reading, an incident reading provides exposure information for rendering average subjects correctly, making incident readings most accurate when the subject is not extremely bright or dark.

Index Print – Reduced display of several photos on one print.

Image Resolution – The number of pixels per unit length of image. For example, pixels per inch, pixels per millimeter, or pixels wide.

Image Sensor – A traditional camera exposes a piece of light-sensitive film, digital cameras use an electronic image sensor to gather the image data (CCD – CMOS).

Image Stabilization (IS) – An optical system for removing, or reducing camera movement in zoom lenses. Using gyroscopes, an internal lens is moved around to counteract the movement of the camera. This usually allows you to shoot at 2 to 3 stops slower, than a camera without IS under the same conditions.

Infrared Filter – One such filter is the Hoya R72 filter. It is basically a standard screw on filter that you can get for nearly any lens that blocks all visible light, only allowing infrared light through. A very dark red filter; passes light only 720nm and longer, making this filter not quite a pure infrared filter, but a "near infrared" filter. The catch to this approach is that because you still have the built in filter blocking most infrared light, you have to utilize fairly long exposures on the order of 3-10 seconds. Some digital cameras are better for this than others, but all of them will work. Of course a tripod or some form of camera support, is necessary with these long exposure times.

Infrared Photography – The film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about 900 nm. Usually an "infrared filter" is used; this lets infrared (IR) light pass through to the camera but blocks all, or most of the visible light spectrum (and thus looks black or deep red).

Interpolated – Software programs can enlarge image resolution beyond the actual resolution, by adding extra pixels using complex mathematic calculations.

IQ – Acronym for "Image Quality".

IR – "InfraRed" (aka IrDA) – Uses an invisible (to humans) beam of light to either wirelessly control a device, or as a method of transferring data from camera to computer (or printer) without cables. Some cameras also employ infrared in the auto focusing system.

ISO – The speed or specific light-sensitivity of a camera is rated by ISO numbers such as 100, 400, etc. The higher the number, the more sensitive it is to light. As with film, the higher speeds usually induce more electronic noise so the image gets grainier. ISO is the abbreviation for International Standards Organization. (In the good old days it was known as the "ASA film speed").



Jaggies – Slang term for the stair-stepped appearance of a curved or angled line in digital imaging. The smaller the pixels, and the greater their number, the less apparent the "jaggies". Also known as pixilation.

JAVA – A programming language developed by SUN. Among its features is the possibility, to program interactive software for the internet.

JFIF – JPEG File Interchange Format. Technically, JPEG defines a file compression system, not a file format. JFIF is the file format used by most JPEG documents. In real life, however, people talk about JPEG files, not JFIF files.

JPEG – Joint Photographic Experts Group. The de facto standard for image compression in digital imaging devices which enables different levels of compression to be selected. Because brightness information is more important than color data, most pixels only store the brightness information. When the JPEG file is opened, the missing color data is automatically calculated from the existing information.



KB – Acronym for "Kilobyte".

Kelvin Scale – Temperature scale beginning at absolute zero (approx. -273° Celsius = 0 Kelvin). Celsius values can easily be converted into Kelvin by adding 273 degrees to the Celsius value. The color temperature of average Day Light, is 5500º Kelvin. This system of color temperature measurement, is how your digital camera determines white balance for various light sources.

Key Light – The main subject-illuminating light source, particularly in a studio lighting situation.

Kilobyte – 1 Kilobyte equals 1,024 bytes.



LCD – Liquid Crystal Display. LCDs are commonly used in calculators, watches, digital cameras, and notebook computers.

LED – A Light Emitting Diode is often used as an indicator lamp, and focusing aid in Digital Cameras.

Lens – Transparent glass or plastic that has been formed and polished to form a certain shape, usually spherical. When a beam of light reaches the area between the air and the lens, a part of this light is always reflected. The remaining light passes into the lens and alters its propagation direction, (i.e. the light is refracted). The incorporation of various lenses (converging and diverging lenses) creates a lens system. When optimally arranged, they allow the subject to be presented correctly on the image plane.

Lens System – Group of lenses (sometimes just one lens) that enable the sharpest, and brightest pictures to be taken. Often simply referred to as the lens or objective. There are various lenses available such as wide-angle, normal, macro, and tele with fixed focal distances, as well as zoom lenses with adjustable focal distances.

Light Intensity – The relationship of the maximum diameter of an objective to its focal distance. It is equal to the smallest aperture value (i.e. the largest opening). Whereas the zoom lenses on analog cameras have a light intensity of F4, good digital cameras have lenses with a value of F2.
(2) The light intensity from sources of light measured in Candle Power.

Light Meter – To ensure correct exposure, most analog and digital cameras feature automatic light metering.

Li-Ion – "Lithium-Ion battery". Some digicams are packaged with a lithium-ion rechargeable battery pack. Lithium batteries are lighter but more costly than Ni-MH, or Ni-Cad type of rechargeable cells. Lithium cells can be recharged regardless of their state of discharge, they're lighter in weight and maintain a charge better in colder temperatures. Li-ion also holds a charge longer when idle, and are not rated on the number of charge/discharge life cycles but on time – typically 2 – 3 years from the manufactured date.

Lossless – Image and data compression that reduces the file size without data loss (BMP, TIFF).

Lossy – Image compression, such as JPEG, that reduces the size of the image through the loss of some information.

Low Key – Images that contain predominately mid to darker tones, with few highlights. Contrast in low key images is usually sharp, or very dramatic. bordering on under-exposure.

LPI – "lines Per Inch". Unit of measurement for the resolution of printed images.



Macro Converter – Lens attachment that permits fascinating, and very close detailed shots.

Macro photography – Is close-up photography; the classical definition is that the image projected on the "film plane" (i.e film or a digital sensor) is close to the same size as the subject. Most macro lenses achieve at least 1:2, that is to say, the image on the film is 1/2 the size of the object being photographed.
In recent years, the term "macro" has been used in marketing material to mean being able to focus on a subject close enough so that when a regular 4×6 inch (102×152 mm) print is made, the image is life-size or larger. This requires a magnification ratio of only approximately 1:4, more easily attainable by lens makers.

Matrix metering – In most digicams there is a matrix metering option, which uses 256 areas of the frame to calculate the best overall exposure value.

MB – Acronym for "Megabyte".

Megabyte – 1 MB equals 1,024 kilobytes.

Microdrive – IBM/Hitachi miniature hard disk drive for digital cameras, PDAs and MP3 players. Packaged in a CompactFlash Type II housing, and available in 170MB to 8GB capacities.

Memory Stick – A memory medium developed by Sony.

Memory Stick Duo – A smaller version of Sony's Memory Stick, about the same physical size as SD cards, and used in all of Sony's compact digicams from 2005 to current. Available in capacities up to 4GB currently.

MMC – "MultiMedia Card", a flash memory card used in some digicams, and MP3 players. It is identical in size and shape to the Secure Digital (SD) flash cards.

Moire – An interference pattern brought about when images of differing resolution are superimposed. (This problem may occur, for example, if small diamond shapes are to be reproduced on a television screen).

Monopod – Also called a unipod, is a pole used to help support cameras, video cameras (or, less frequently, binoculars). It allows a still camera to be held steadier, allowing the photographer to take sharp pictures at slower shutter speeds, and/or with longer focal length lenses.

Motion JPEG – Some digital cameras such as the DMC-TZ1 from Panasonic, can record a fast sequence of images in QuickTime Motion JEPG format.

MPEG – Motion Picture Expert Group. The abbreviation is used to describe a compression format for digitized video images.

Multi-Pattern Metering – Exposure is determined by reading many different zones in the frame. This yields a more optimum exposure than those cameras using only a central zone metering system.

Multi-Point Focusing – The autofocus systems uses SEVERAL different portions of the image to determine the proper focus.

Multi Zone Focusing – Many digital cameras now offer multi zone focusing. The camera will automatically determine which zone (center, left, right, upper, lower) to use to perform the auto focusing. You no longer have to make sure that your subject is dead-center to be properly focused.



Natural Light – Photographically speaking, any light which originates from the sun.

NEF – Raw image data file format used by the Nikon digital SLR (D1x, D100, etc), and some Coolpix digicams. NEF means "Nikon Electronic Format".

Neutral Density Filter – A filter which reduces the amount of light passing through the lens, but which does not add a color cast (ie: it attenuates all wavelengths of light equally).
(2) Graduated Neutral Density filters; are also available that reduce light only in certain areas of the image, (e.g. Upper; Sky – Lower; Water).

Ni-Cad – "Nickel-Cadmium battery". Older rechargeable technology, suitable for low constant current devices. Ni-Cad batteries are not suitable for the high current demands of digital cameras, and do not do well in cold weather. Careful charging/discharging is also necessary to keep these batteries, from forming a short duty memory cycle.

Ni-Mh – "Nickel-Metal Hydride battery". Rechargeable batteries that have an energy density 100% higher than Ni-Cad batteries, and can supply high energy levels when required, e.g. when using the flash in quick succession. They can be recharged more than 500 times on average, and are environmentally-friendly (free of cadmium and mercury). Among other devices, Ni-Mh are used to power digital cameras. Ni-Mh batteries loose about 1% of their charge a day when stored, and require monthly recharging regardless of use.

Noise – Pixels in your digital image that were misinterpreted. Usually occurs when you shoot a long exposure (beyond 1/2-second) or when you use the higher ISO values from 400 or above. It appears as random groups/patches of red, green or blue pixels.

Noise Reduction – Some cameras that offer long shutter speeds (exceeding 1 second) usually have a noise reduction (NR) feature that is either automatic, or can be enabled in the menu. This is to help eliminate random "hot" pixels, and other image noise.

NR – Acronym for "Noise Reduction".

NTSC – Term used to describe the 60 field video output (television) standard used in the U.S. and Japan.



Opacity – A ratio indicating how opaque a material is. The ratio is between the amount of light shining onto a substance, and the amount transmitted through it.

Opaque – In the context of photography, a material which blocks the passage of light.

Optical Image Stabilization – often abbreviated as OIS, is a mechanism used in a digital still camera or video camera that stabilizes (reduces hand shake) the recorded image by varying the optical path to the sensor. This technology is implemented in the lens itself, rather than in the camera. The primary reason for this is that placing the system in the camera body, would require placing additional glass lenses within the camera itself, increasing the size of the camera dramatically.
Also, placing the IS inside the lens allows for the system, to be fine-tuned for the characteristics of that particular lens. Different companies have different names for the OIS technology; for example, Canon, the pioneer of the technology and the first to produce an OIS lens, calls it Image Stabilization (IS), Nikon calls it Vibration Reduction (VR), Panasonic and Leica call it MegaOIS.

Optical Viewfinder – Many optical viewfinders have tunnel vision, and don't show you the entire scene the lens will capture. Don't be surprised if the image you see in the viewfinder, is not! what you see when you look at the photo later.

Optical Real Image Viewfinder – Shows the actual image area that can be photographed. Canon has incorporated this type of optical viewfinder, into many of their PowerShot series cameras.

Optical Zoom – Means that the camera has a real multi-focal length lens, this is not the same as a "Digital Zoom" which magnifies the center portion of the picture.

Orientation Sensor – A special sensor in some cameras that "knows" when your turn the camera in portrait orientation to take a vertical shot, and "tells" the camera to display it that way later when viewed on the TV screen during playback.

Overexposure – An image that appears too light. All the highlights and colors are totally lost, and usually unrecoverable even by software.



PAL – The 50 field video format used primarily in Europe, and other places outside of the U.S. and Japan.

Panorama Card – SmartMedia function card. To assist in stitching of panoramas.

Panoramic Image – An image produced by stitching several consecutive frames of a scene together, to produce one wide area view. There are several good programs, devoted singly to creating panoramic images; one is "Panorama Factory".

Pan & Tilt Head – A common tripod head designed for video applications. That can pan horizontally, and tilt vertically. But lacks the full unidirectional movement, of the still image ball head. Therefore; is not as convenient on uneven surfaces (i.e. field work outside of the studio).

Parallax – An effect seen in closeup photography where the viewfinder does not see the same as the lens, due to the offset of the viewfinder and the lens. This is a non-issue if using the LCD as a viewfinder, or if your camera is a SLR type.

PC Card – Refers to a credit card-sized device which can be a flash memory card, a network card, a modem or even a hard drive. Comes in two flavors: Type I/II which is a single slot height, and Type III which requires a double-height card slot.

PCMCIA – The card slots found on laptop computers to use PC Cards. There are PCMCIA adapters for CompactFlash, SmartMedia, Secure Digital, MultiMediaCard, and Memory Stick flash cards.

Photo CD – A process developed by Kodak and Philip's that enables the digital storage of conventional photographs, and slides on a CD-ROM. As such, the digitized picture may be loaded into a computer, and viewed or edited like other digital images.

Photocell – Photodiode.

Photodiode – A semiconductor which measures or converts light into an electrical current. Photodiodes are commonly used in scanners, CCD sensors, and exposure meters.

Photoshop – Popular image processing program.

Pincushion Distortion – A common form of lens flaw or aberration, curvilinear distortion, in which parallel lines on the edge of the frame appear to bow inwards. Also known as positive distortion. Computer monitors are susceptible to the same problem, albeit for very different underlying technical reasons.

Pixel – The pixel is the smallest element of a raster display or digital image, and contains information about intensity and color. A pixel can be either square or rectangular. Generally, monitors or ink-jet printers consist of a pixel with up to 256 dots per color. Exception: dye-sublimation printer.

Pixelization – The stair-stepped appearance of a curved or angled line in digital imaging. The smaller the pixels, and the greater their number, the less apparent the "pixelization" of the image. Also known as the "jaggies".

Pixel Modulation – A process used in printing which changes the brightness of individual pixels, by changing the pixel size.

P Mode – "Program Mode". Is a fully automatic camera function. Where the camera sets shutter speed, aperture, and ISO, according to the available light for correct exposure. Some cameras allow for manual selection of ISO, in p mode.

Point and Shoot (P&S) – A term used for a simple, easy to use camera with a minimum of user controls. Generally the user turns the camera on, aims it at the subject, and presses the shutter button. The camera does everything automatically.

Polarizing Filter – Also "polarising filter," "polariser," "polarizer". A filter which can block light polarized in one plane. This useful property means a polarizer can cut non-metallic reflections, and enhance contrast in your photos under certain conditions. Polarizers are useful for cutting reflections from water and glass (ie: non-metallic) surfaces.
They're commonly used for cutting reflective glare off of windows, or for taking a photo of a lake without a reflection on the lake surface, for instance. They can also be used to increase color saturation of blue sky. There are two basic kinds of polarizers, linear and circular. Linear polarizers work well with manual focus cameras, but they interfere with autofocus cameras. For this reason; circular polarizers are the best choice for digital cameras.

PPI – Printing term for pixel per inch. Indicates the number of pixels a scanner or digital camera can process per inch.

Pre-Flash – Some digicams use a low-power flash before the main flash to set the exposure, and white balance. This does not allow the use of a normal photo slave strobe, as it will be triggered by the pre-flash.

Programmed AE – The camera picks the best shutter speed and aperture automatically, also called "Automatic" or "Point-n-Shoot" mode.

Progressive CCD – Describes a CCD specially developed for digital cameras.

.PSD – Photoshop file.



QFX – A high level photo retouching program for PCs.

Quick Release (QR) Plate – A metal plate which fits between a tripod (or monopod, etc) head and a camera. The plate screws into the camera's tripod mount and clips onto the tripod head. It allows a photographer to attach and remove the camera to and from the tripod mount quickly, without having to waste time fumbling with the threaded mount.

Quick Shooting Mode – This function allows a number of photos to be taken in quick succession, (usually with one to two seconds between each shot). With a large memory (D-RAM) it is even possible to take high resolution shots, with only a tenth of a second between them. The images are then later saved onto the cards.

QuickTime – Developed by Apple, this is a standard for digital videos, and streaming media. More than half of all internet videos are in QuickTime format.



Rangefinder – The viewfinder on most cameras, is a separate viewing device that is independent of the lens. Often mounted above, and to the right or left of the lens. It exhibits a problem known as parallax when trying to frame subjects closer than five feet from the camera so it is advisable to use the color LCD when shooting closeups for this very reason.
(2) A name given to 35mm cameras, that used a rangefinder system for focusing the lens.

RAW – RAW files store the unprocessed image data – at 12 bits per channel – from the camera's imaging chip to its memory storage device. Lossless compression is applied to reduce filesize slightly without compromising any quality. RAW image files must be processed with special software before they can be viewed or printed.
The advantage is that you have the ability to alter the white balance, exposure value, color values, contrast, brightness, and sharpness as you see fit before you convert this data into the standard JPEG or TIFF format. Professional digi-photographers import RAW image data directly into photo-editing programs like Photoshop CS (which comes with a Camera Raw import module that works with most popular RAW formats.)

Real Image Viewfinder – Optical real image viewfinder.

Red-Eye – An effect caused by an electronic flash reflecting off of the human eye, and making it look red. Compact cameras with the flash located close to the lens suffer the worst from this problem. Pro photographers use a bracket to hold an external flash unit above, and off to the side of the lens to eliminate red-eye.

Red-Eye Reduction Mode – A special flash mode whereby a pre-flash, or a series of low-powered flashes are emitted before the main flash goes off to expose the picture. This causes the pupil in the human eye to close, and helps eliminate red-eye.

Reflected Light Metering – Method of exposure metering, by which the amount of light reflected from the subject is measured.

Resolution – Measurement of the image detail (dots per inch/centimeter) that a device can capture or reproduce. With a monitor or printer, the resolution describes the number of pixels that can be shown. When used for devices for image capture, such as digital cameras or scanners, the resolution refers to the number of pixels that can be captured.
The result is given in dpi ("dots per inch" 1 inch equals 2.54 cm), the horizontal and vertical total of pixels (e.g. 1,712 x 1,368 or 1,280 x 1,024) or in (lpmm line pairs per millimeter), which describes the highest number of thin black and white lines that can be displayed per millimeter. A good small image film has, for example, a resolution of approximately 150 lpmm (300 dpi rounded out to 118 dots per centimeter). In general, it can be said that the higher the resolution, the better the quality.

RGB – "Red, Green, Blue". The three basic colors for additive color mixing.

ROM – Read Only Memory. This type of memory storage only allows the user to "read" the information it contains, i.e. the user cannot store (write) any information on the ROM. Once written, the contents of the ROM cannot be changed.



Saturation – The degree to which a color is undiluted by white light. If a color is 100 percent saturated, it contains no white light. If a color has no saturation, it is a shade of gray.

Scanner – A device used to digitize printed information (pictures, graphics, and text).

Scene Modes – Many digicams now have an exposure mode called SCENE, where the user selects the best pre-programmed scene to suit the current shooting conditions. The camera will automatically change many settings to capture the best possible image.

SD – "Secure Digital Card", the most popular type of flash memory card used in digicams today. Identical in size and shape to the MultiMedia Card (MMC) flash cards. The difference being that SD cards were designed to hold protected (copyrighted) data like songs. Not all cameras that use SD cards can use MMC cards, so be sure to read your owner manual before buying additional cards.

SDHC – "Secure Digital High Capacity" cards allow capacities in excess of 2GB (4GB to 32GB). SDHC uses the same form factor as SD, but is not compatible with older non-SDHC devices. The SD 2.0 standard in SDHC uses a different memory addressing method (sector addressing vs byte addressing), causing devices that do not specifically support SD 2.0 / SDHC to fail to recognize the memory cards. Note this means that SDHC cards also require a card reader that specifically supports the new SD 2.0 standard, older card readers will not recognize SDHC cards.

Selective Multi-Zone Metering – This mode is also called matrix, evaluative, honeycomb, segment metering, or esp – (electro selective pattern) metering on some cameras. This metering mode was first introduced by the Nikon FA, where it was called Automatic Multi-Pattern metering. On a number of cameras this is the default/standard metering setting.
Here the camera measures the light intensity in several points in the scene, and then combines the results to find the settings for the best exposure. How they are combined/calculated deviates from camera to camera. The actual number of zones used varies wildly, from several to over a thousand. However performance should not be concluded on the number of zones alone, or the layout. In general, the most advanced metering is found on Digital Single Lens Reflex (DSLR) cameras.

Self Timer – A function that delays the opening of the shutter. This ensures vibration-free operation during long exposure times, and enables the photographer to get into the picture.

Sepia – The (brown) mono-toned images from the "good ole days", now often found as a special image effect on some digicams.

Sequence Mode – Several shots are taken automatically in a row.

Shadow Clipping – Shadow clipping is said to occur when no detail is visible, i.e. the shadow areas are solid black.

SHQ-Resolution – "Super High Quality-resolution". A very high resolution digital photo.

Shutter – A mechanical device placed either between elements, or behind the lens. That determines the amount of time light can reach the CCD or film plane, controlling exposure. In most point and shoot digital cameras, there is no actual shutter. Exposure is determined electronically, by turning on and off current to the CCD.

Shutter Lag – The time between pressing the shutter and actually capturing the image. This is due to the camera having to calculate the exposure, set the white balance and focus the lens.

Shutter Priority (Tv) – Allows the user to select the desired shutter speed, and the camera automatically chooses the correct aperture for exposure.

Single Lens Reflex Camera – Camera type that directs the image coming in through the lens up into the viewfinder by means of a mirror. When the shutter is released the mirror swings up to allow light on the image plane. For fast sequence shooting and to reduce vibrations, some SLR optical systems use a beam splitter (prism) instead of the quick return swinging mirror. The picture seen through the viewfinder is almost 100% identical to the resulting photo.

Skylite Filter – A filter which absorbs ultraviolet radiation, and which is also usually tinted light pink or yellow in order to cut back on some of the blueness in an image caused by skylight. A type of warming filter. Not necessary with digital cameras, but sometimes used for lens protection.

SLR – Acronym for Single Lens Reflex.

Slow Sync Shutter – There are two basic ways in which a camera can take a flash photo when light levels are low. The camera can either use a short shutter speed to minimize camera motion blur, and have the flash blast out enough light to illuminate the foreground objects while leaving the background dark, or the camera can extend the shutter time to allow more of the background to show up, and flash-illuminate the foreground subject. This latter technique is called slow sync, slow shutter sync or "dragging" the shutter.
A typical example is a tourist snapshot of someone standing in front of a famous landmark at night. If you keep the shutter speed fast then you'll have a nice flash-illuminated photo of your friend against a pitch black backdrop, unless the landmark is extremely brightly lit or unless you're using a very high ISO. However, by slowing down the shutter speed you can take a photo of the person standing against a properly exposed background.
The drawback is obvious, of course. By slowing the shutter speed you're going to need a tripod to avoid blur induced by camera movement, especially with long shutter speeds like 1/15 second or slower.

SmartMedia – (aka SSFDC) – a flash memory card that consists of a thin piece of plastic with laminated memory on the surface, and uses a gold contact strip to connect to the camera. SmartMedia cards are available from 4MB up to 128MB in size, and have been discontinued and replaced by XD-Picture Card media for use in Fujifilm, and Olympus digital cameras.

Spherical Aberration – In optics , spherical aberration is a deviation from the norm resulting in an image imperfection, that occurs due to the increased refraction of light rays that occurs when rays strike a lens or a reflection of light rays that occurs when rays strike a mirror near its edge, in comparison with those that strike nearer the center. In lens systems, the effect can be minimized using special combinations of convex and concave lenses , as well as using aspheric lenses.

Spot Metering – Exposure metering method whereby the exposure reading is taken from the center of the frame. This is often used when working with backlight.

Soft – Lacking contrast; having a long tonal scale.

SQ-Resolution – Standard Quality resolution.

Stop Down – A term used in photography, that means to change to a higher aperture number (e.g.  F-16). To reduce the light reaching the CCD or film plane. Also used to increase the depth of field.

Stop Up – A term used in photography, that to means to a change to a lower aperture number (e.g.  F-2.8). To increase the light reaching the CCD or film plane. Also used to reduce the depth of field.

Subtractive Color Mixing – A special method for the production of color prints that involves layering the colors cyan, magenta, yellow, and black in appropriate proportions, to produce the required colors.

SVGA – "Super Video Graphics Array". Refers to a display screen resolution of more than 800 x 600 pixels.

SXGA – "Super Extended Graphics Array". Describes a resolution from 1,280 x 1,024 image pixels.



Tele Converter – Lens attachment that extends the focal length.

Telephoto – The focal length that gives you the narrowest angle of coverage, good for bringing distant objects closer.

Thumbnail – The miniature representation of a digital image, that usually serves as a preview function in image editing programs.

TIFF – "Tagged Image File Format". A specific, high quality file format (un-compressed), used for the storage of digitized images.

Transreflective – This is a type of LCD display that uses ambient light, as well as a backlight to illuminate the pixels. Can be seen easier in bright outdoor conditions.

Tripod – Is a term generally used to refer to a three-legged object. Commonly one used as a camera platform, to eliminate image blurring at slow shutter speeds, and long focal lengths. Also for precise focusing, when doing "Macro Photography".

True Color – Describes the color output on a monitor or printer. Requires at least 16 million color nuances.

TTL Metering (TTL) – Through The Lens metering. This means the camera reads, and set the subject exposure through the lens. Cameras with a "Hot-Shoe" read exposure for electronic flash units in this way also.



Underexposure – A picture that appears too dark because insufficient light was delivered to the imaging system. Opposite of overexposure.

Unsharp Masking – Often abbreviated USM. Describes an image focusing (sharpening) process. The quality of the result depends on the characteristics of the algorithm used.

USB – "Universal Serial Bus". USB enables the effortless connection of peripheral devices without the need to install cards into the computer, or reconfigure parts of the operating system. The most important advantages are: the support of Plug and Play, hot plugging, automatic configuration of external devices upon connection (no re-start necessary), faster data transfer (up to 12 Mbps), and the possible operation of up to 127 devices from a single port.

USB 2.0 – The newest USB standard, close in throughput speed to FireWire now. Up to 400Mb/s, that's Megabits per second not MegaBytes.

UV Filter – A clear filter which can block many wavelengths of ultraviolet energy. Used on digital cameras, only as a protection for the lens. Digital cameras have sufficient UV protection built in.

UV Photography (ultraviolet) – Compared with visual-light shooting, you can expect any kind of UV photography to give from 6 up to 15 stops longer exposures, so by necessity a tripod should be used. The apparent loss of film/digital sensitivity is largely caused by UV intensity itself being so much lower than visible light levels, but a further loss occur due to lens, and the recording media (film or digital sensors). Only near UV is of interest for UV photography, for several reasons. Ordinary air is opaque to wavelengths below about 200 nm, and lens glass is opaque below about 180nm. The normal range for UV photography is from 200 – 400 nm.

UXGA – "Ultra Extended Graphics Array". This refers to images with a resolution of 1,600 x 1,280 pixels.



Variable Aperture Zoom Lens – A zoom lens which has different maximum apertures at different focal lengths. This type of lens, is used on most Point and shoot digital cameras.

VGA – Video Graphics Array. Refers to a display screen with a resolution of 640 x 480 pixels.

Viewfinder – Also just "finder." Typically, the little window at the back of a camera into which the photographer peers in order to preview the scene prior to taking the photograph. Limited to 80 – 85%, of the actual image area.

Vignette – The transition of color from one set value of hue and saturation to another over a given distance, in vertical, horizontal or circular directions. A shadow condition at the corners of an image, sometimes caused by extension tubes, or stacked filters.

VR – "Vibration Reduction". Nikon's equivalent to the Canon IS system.



Warm – Color which is yellowish in tint or tone. Light with a low color temperature is said to be warm light, confusingly enough.

Watermark – A mark, logo, symbol, etc., superimposed over part of a picture.

White Balance (WB) – The adjustment of a digital camera to the respective type of light. In addition to the automatic white balance, it is often possible to choose between "daylight", "overcast", "tungsten", and "neon light" for even truer colors or, on the other hand, create a different, striking effect.

Wide Angle Converter – Lens attachment that reduces the focal length.

Wide Open – Colloquial expression for a lens which has its aperture diaphragm set to its largest aperture, the smallest possible f stop value. At this aperture the lens lets in the most light it can.

Wood Effect – The bright glow seen from sun–illuminated deciduous trees, and other types of plants when photographed using infrared film; an effect named after its discoverer.



XD-Picture Card – A flash memory card standard that was co-developed by Fujifilm, and Olympus in mid-2002. It has replaced SmartMedia cards which topped out at 128MB, and is now out of production. XD cards are scheduled to go as large as 8GB, and currently are available up to 2GB.

Xenon – A "noble" (almost inert) gas, commonly used in electronic flash tubes. Occasionally referred to as a Xenon flash.

XGA – "Extended Graphics Array". A graphics standard developed by IBM, which allows the display of 1,024 x 768 pixels with up to 65,535 colors.

X3 Image Sensor – Foveon's new image sensor for digital cameras that captures red, green, and blue data at every pixel.

X-Sync – Flash synchronization with electronic flash.



Yellow – A color with wavelengths of around 580nm. Yellow, along with cyan and magenta, is one of the three subtractive primary colors.

Yellow K2 Filter (Hoya) – Especially useful for clear contrast between blue sky with clouds and foreground. Provides a natural tonal rendition. Often used for subjects at intermediate distances. Also used in architectural photography to increase contrasting shadows, and lines. Primarily used in black and white photography, but can be used with color to add some special effects.



Zeiss – German optics manufacturer Carl Zeiss.

ZIP – File format used for data compression.

Zip-Drive – A disc device similar to a floppy but larger, that allows the storage of up to 250 MB of data.

ZLR – Zoom Lens Reflex, a term coined by Olympus to describe their fixed mount lens SLR type cameras. An SLR camera has interchangeable lenses, a ZLR has a non-removeable zoom lens.

Zone Focusing – A method of focusing the lens, so that the depth of field extends over a preselected range of distances.

Zone System – A method for determining correct exposures of negatives, developed by American photographer Ansel Adams, and his colleague Fred Archer.
Zone metering involves dividing up the scene into a set number of discrete light levels, typically 9 or 10, but some photographers advocate more, especially for color film. Zone 0 or I represents pure black, and zone IX pure white on the final print.

Zoom Flash – A flash with the capability to adjust the width and range of its light beam, to best fit the angle of view of the lens in use.

Zoom Lens – Lens with a manually, or a mechanically adjustable focal length. A true zoom lens (high quality), is one that will hold a constant aperture through out its entire focal length.

Zuiko – Lenses sold by Olympus to fit their OM series of cameras, were marketed under the Zuiko name.