Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

Aberration

Image distortion and colour changes caused by the spherical surface of the lens. A common lens problem, it reduces sharpness and contrast, and causes images to become wavy or curved. Aspherical lenses minimize aberration.

Active AF

One method of auto focus where infrared beams, ultrasonic waves or other waves are sent from the camera to the subject. The reflected beams or waves are then detected by the camera and used to calculate the focus distance.

A/D Converter

Analog-to-Digital Converter. A device that converts (digitizes) analog data/signals to digital.

Adobe RGB

This colour space was proposed by Adobe Systems Incorporated in 1998. Featuring a wider color spectrum than sRGB, it is a standard color space for printing, but the number of compatible monitors and printers is still relatively small.

AE

Abbreviation for Automatic Exposure. The camera's exposure sensor measures the brightness of the subject and automatically calculates an exposure. Generally, there are three types of AE: Program AE, Aperture Priority AE and Shutter Priority AE.

AE Lock

Automatic Exposure Lock. Once the camera has calculated the AE values, activating the AE Lock saves those values.

AF

Automatic Focus. This feature automatically focuses the camera's lens. Also known as "Auto Focus."

AF Frame

Auto Focus Frame. Visible in the viewfinder, this frame indicates the area used for auto focus.

AF Lens

Auto Focus Lens. A term for lenses specifically designed to use the camera's auto focus function.

AF Lock

Auto Focus Lock. Once the camera has focused the lens, activating AF Lock locks the focus at that distance.

Aperture

Working much like the pupil of the eye, the movement of the lens' internal aperture blades closes or opens the aperture to adjust the amount of light passing through the lens. The value inscribed on the aperture ring of the lens (F1.4, F2, F2.8, etc.) represents the size of the aperture and is called the "aperture value" or "f-stop." As this value increases, the aperture narrows, or is "closed," and as it decreases, the aperture widens, or is "opened."

Aperture Blades

Collectively, these blades form the aperture of the lens. As the number of blades increases, the aperture becomes more rounded, which tends to soften the focus for a more beautiful effect. Conversely, as the number of blades decreases, highlights take on polygonal shapes.

Aperture Priority AE

After the photographer sets the desired aperture, the camera automatically calculates the correct shutter speed. Used to control pan-focus or depth-of-field, for determining the level of soft focus.

APO Lens

Apochromatic Lens. A high-quality lens that uses special low-dispersion optical glass to greatly reduce chromatic aberration.

APS

Abbreviation for Advanced Photo System. A film system that uses IX240-type film. Two magnetic tracks, one on each side of the film, allow improved film/developer communication. Each roll is completely enclosed in a plastic cartridge, allowing easy drop-in loading.

Artificial Light

Includes man-made lighting used in offices and homes, such as fluorescent or incandescent, in addition to flash.

Aspect Ratio

Represents the ratio of the screen's height to the width. The ratio with 35mm film is 2:3. Digital cameras are usually 3:4.

Aspherical Lens

Normally, a portion of the spherical front surface of a lens contains aberrations. Lens designers, as they strove to create a perfectly curved lens face, ultimately created a non- spherical, or aspherical lens.

Auto Flash

A flash unit that uses a special light receptor to automatically calculate the required amount of flash light required, based on the distance from the subject.

Auto Focus (AF)

Automatically focuses the camera's lens on the subject. Among the most common systems are "Active AF," which sends infrared beams, ultrasonic waves or other waves from the camera to the subject and the reflected beams or waves are used to calculate the focus distance. Similarly, "Phase Differential Detection" calculates distance based on the phase difference of incoming beams bounced off the subject. Another is the "Contrast Detection" method, which uses differences in contrast in the CCD's image to calculate range.

Automatic Exposure Bracketing (AEB)

Automatically takes multiple pictures with a single press of the shutter, each using a different exposure. (Usually average, over and under exposed.) This reduces the chance of an incorrect exposure.

Av

Abbreviation for Aperture Value.

AVI

Abbreviation for Audio Visual Interleaved. One format of video that can be read by video player software (like Windows Media Player). Uses the ".avi" file extension.

AWB

Auto White Balance. Feature that automatically adjusts the camera's white balance by setting the image's color temperature to produce colors the same as those seen by the naked eye.

back to top

B

Back Focus

A term for when the part in focus is not the subject, but the area behind the subject. The term "back focusing" is often used to describe mistakes where the background is in focus instead of the intended subject.

Backlight

The term used when light strikes the subject from the rear. Normally this causes the subject to become a silhouette, however, using a flash to light the subject from the front will prevent this effect.

Bayonet Mount

Like the bayonet of a rifle, lenses with this mount require only a single movement to attach them securely in place. This type of lens mount is now the most popular type of mount for single lens reflex cameras.

Black and White (Monochrome) Film

Most often used for capturing a scene's brightness and color tone using only shades of light and dark. Negative B&W film is also available, which reverses these shades.

Blind Shooting

A street photography technique in which photographs are taken without looking through the viewfinder so as not to alert the subject. Allows the photographer to capture natural, non-posed shots.

Blocking

Digital cameras can accurately reproduce only a finite range of color gradation, from white to black, when recording an image. If this range is too narrow, certain colors will not be accurately recorded. This can result in dark areas becoming completely black, with no gradation, and is called blocking.

Blocking/Blow-Out

Graphically describes the tone of a photograph. Blocking refers to the subject's shadow sections, where tone detail has turned to black. Blow-out refers to highlight sections, where tone detail has turned to white.

Blur

Any area of an image that is not in focus.

BMP

Standard image file format for Windows.

Bounce Lighting

Instead of focusing light directly on the subject, light is bounced/reflected off a wall or ceiling. This is especially useful for portrait photography and close-ups. Bouncing the light has the effect of softening it, which makes subject shadows less noticeable.

Brownie Film

Used in medium-format cameras. Standard film lengths are 120 and 220, which means that a 120 roll can take 12 6x6 photos, and a 220 roll can take 24.

Buffer Memory

When images are captured with a digital camera, writing them to the memory card requires a certain amount of time. To free up the camera while data is being written, data is first sent to the camera's buffer memory, which allows the camera to quickly take the next picture.

Built-in Flash

A small internal flash unit located at or near the top of the camera.

Bulb (B)

In this shooting mode, pressing and holding down the shutter button keeps the camera's shutter open and continues to expose the film.

back to top

C

Calibration

Calibration refers to adjusting the colors so they display correctly on a PC monitor. It sets the color temperature and gamma values while taking into consideration the ambient light, light reflected inside the lens, the colors of rooms, etc. Special calibration software is generally used to make these settings.

35mm Camera

A widely used type of camera that uses 35mm-wide film.

Camera Angle

Describes the angle of the camera relative to the subject. If the camera is looking up at the subject, it is called a low-angle shot, and if the camera is looking down on the subject, it is called a high-angle shot.

Camera Position

The position of the camera when the picture is taken. This is a general term for the camera's position relative to the subject.

Cartridge

The term for the plastic containers used to hold all types of roll film, such as APS film.

CCD

Abbreviation for Charge Coupled Device. CCDs are one of a number of image sensor types that convert light focused on them by the lens into electrical signals. In a digital camera, the CCD performs the same basic function as the film of a silver halide film camera.

CD-R/RW

"CD-R" indicates a CD disk that can record (write) data one time, but cannot delete it. "CD-RW" indicates a CD disk that allows multiple writing and deleting of data. Devices that use this mark have both types of functionality and can use both types of media.

Center-Weighted Average Metering

This metering method places the emphasis on the center of the image and measures the average brightness of the entire image. It is the most common metering method, and is used on most digital cameras.

Close-Up Lens

Like a filter, this accessory lens is attached to the front of the lens and allows photography of subjects at short distances. The convex surface of the lens acts like a magnifying glass.

Close-Up Photography

Photographs of a subject from a close distance. Usually, these photos are taken just beyond the minimum focal distance (1/10x) of a standard fixed lens.

CMOS

Complementary Metal Oxide Semiconductor. Similar to a CCD-type image sensor. Capable of extremely fast signal readout and uses comparatively little power. Other merits include compact design and low manufacturing costs.

CMYK

Abbreviation for cyan, magenta, yellow, and black; the inks used in process printing. In printing, when combined in various percentages, these four inks will create an entire spectrum of colours.

Colour Balance

Describes the accuracy of the colours reproduced on colour film, a print or a monitor. Correctly reproduced colours indicate a good colour balance, and incorrectly reproduced colours indicate a poor colour balance.

Colour Cast

Image has a tint of a single colour. For example if a picture is taken in fluorescent lighting without the camera's white balance being set for that type of light, the resulting image is said to have a "blue-green cast."

Color Management

More extensive than color matching, this process unifies the colors among devices such as digital cameras, monitors, printers, and scanners. To do this, it incorporates an international standard of color settings called ICC profiles

Colour Matching

This is the process of making the colors displayed on a PC monitor close to the colors output by a printer. Because the monitor uses three colors (RGB) and the printer uses four (CMYK), data recorded for the coloring characteristics of each piece of equipment is compiled and color matching is performed by a technology called ICM for Windows and ColorSync for Macintosh.

Colour Space

Colour space refers to the color spectrum that can be reproduced in digital images and digital equipment. The most commonly used colour spaces are NTSC, sRGB, and Adobe RGB.

Colour Temperature

Describes the varying levels of natural and artificial light, from weak to strong. The unit is "K" (Kelvin). The standard level is sunlight on a clear day (5500K). Light at higher K levels becomes blue-greenish, and at lower K levels becomes reddish. Adjustment of this level is performed using the white balance setting.

Complementary Colour Filter

Attached to the top (front) face of a CCD, this filter consists of four colors (cyan, magenta, yellow, green) and, compared to a primary color filter, has a high color transmission ratio which improves CCD sensitivity to light.

Composition

Positioning the points, lines, shapes, hues, light and shade of an image to achieve a particular effect.

Compression

A method of reducing the volume of image data by omitting redundant or similar color data. Virtually all digital cameras use the JPEG method of image data compression. While JPEG compression simplifies data handling, it is non-reversible and high levels of compression can produce "artifacts" that affect image quality.

Contrast

The ratio of dark to light in an image. When this ratio is large, contrast is high. When the ratio is small, contrast is low.

Conversion Lens

Attached to the front of the lens to change the focal length. While many types of conversion lenses are available, the most popular are wide-angle, telephoto, and fisheye.

Cosine Error

This refers to the focus deviation that results when the AF is used to focus the image, and then the camera is moved to change the composition.

1st Curtain/2nd Curtain

Identifies the two curtains used in a focal plane shutter-type camera. When the shutter is opened, the curtain that rises first is called the 1st curtain. The next curtain to rise is called the 2nd curtain.

1st Curtain Synchro/2nd Curtain Synchro

Synchronizing the flash to fire just before the shutter's 1st curtain finishes falling is called "setting to the 1st curtain synchro." Similarly, timing the flash to fire the instant before the 2nd curtain starts to rise is called "setting to the 2nd curtain synchro." Each can be used to depict effects such as image traces in a different way.

back to top

D

Daylight Film

A colour temperature of approximately 5500K allows this film to correctly reproduce colours in noontime daylight. The majority of all consumer film sold is daylight film.

Daylight Synchro (Fill Flash)

A fill flash can be used to correct shadows that are cast on the subject by backlighting. If only exposure compensation is used, the background will blow-out to white. Using daylight synchro makes it possible to correctly expose both the background and the subject.

DCF

Abbreviation for Design Rule for Camera File System — an industry standard for recording digital images. This system provides rules for the file types used to record image data to a recording media (such as a memory card).

Depth of Field (DOF)

When a subject is brought into focus, the area just in front of and behind the focus point will also be in clear focus. This range of clarity is called depth of field. Depth of field increases as the lens' angle of view widens, as in a wide- angle lens, and also as the aperture size is reduced (f-stop increases).

Diffused Light

When light is not direct and has a muted quality, it is called diffused light. Typically soft, it mutes subject shadows and makes them less conspicuous. Ideal for portraits and close-up photos. Any type of translucent material (tracing paper, translucent acrylic sheet, white cloth, etc.) placed in front of a light source (flash, lamp, etc.) will produce diffused light.

Digital Zoom

A feature found in many digital cameras that takes a portion of the image's data and displays it at full size, producing an enlargement (magnification) of the original image, similar to the effect of using a telephoto lens. This process, however, is different from the magnification produced using the camera's optical zoom, and the stronger the digital zoom, the more the image will degrade.

Diopter Correction

Allows the photographer to adjust the focus of the camera's optical viewfinder to match his or her eyesight.

Direct Light

The term for strong light, such as sunlight, striking the subject. This kind of light is said to be the "hardest" type of light and will increase the amount of contrast between highlights and shadows.

Direct Print

Prints made directly from a slide. The printing process uses a special paper. However, the prints are expensive and usually have a slightly "harder" look than those made using ordinary negatives.

Direct Strobe/Flash

Lighting where flash light is shined directly on the subject. Using direct flash light reduces the influence of the color of surrounding reflected light. Subjects lit using a direct flash have a stronger look, which in turn strengthens the image's overall impact.

Displacement

A function in large-format and medium-format cameras where the lens can be shifted and tilted with respect to the film plane. Allows adjustments to depth of field and corrections in perspective.

Disposable Camera

Single-use cameras that are popular and easy to use. They consist of a simple case, a shutter button and a film winder, without controls for exposure adjustments or focus.

Distortion

The deforming of all or part of a subject. Distortion exaggerates the feeling of depth in a scene and can be created using a wide-angle or telephoto lens. Recently, PC image editing software can also be used to easily add or correct this effect.

Dot

The smallest component of a digital image. Printers and other devices also use the same name for this unit. While specifications for monitors call this unit a "pixel" and specifications for image sensors (CCDs, etc.) call it a pixel or an image pixel, they indicate the same primary unit.

dpi

Abbreviation for "Dots per Inch." Indicates the resolution of a printer, scanner, or monitor. Refers to the number of dots in a one-inch (approx. 25.4-mm) line.

DPOF

Abbreviation for Digital Print Order Format. A camera function that records printing information on storage media.

DVD-RAM, DVD-RW, DVD+RW

Widely used data storage formats for recording data to writable DVD disks. These disks have a much larger recording capacity than CD-RW disks, hence their use for a wide range of needs, from PC data storage to video recording.

Dynamic Range

The dynamic range expresses the range of dark to light parts that can captured in an image. A wide dynamic range will provide better reproduction of dark and light parts. In film cameras, this is called latitude.

back to top

E

Edge Enhancement

This refers to emphasizing the edges (borders) of the image. It is a type of sharpness processing. By increasing the contrast at the edges, the image becomes sharper.

Effective Pixels

Slightly less than the total number of pixels normally stated for an image sensor (CCD, CMOS, etc.), this term represents the actual number of pixels used to record an image.

Effective Sensitivity

While the ISO system of film sensitivity is calculated based on the film's unique design characteristics, slight deviations from ISO values can occasionally be seen when taking actual pictures. In these cases, the "real" or actual ISO value of these photographs is referred to as the film's effective sensitivity.

Electronic Shutter

Magnetically controls the opening and closing of the shutter.

Emulsion Side

The side of the film on which the light-sensitive emulsion is applied. The primary component of the emulsion is silver halide which, when exposed to light and then developed, produces an image.

EV

Abbreviation for Exposure Value. Indicates the amount of exposure. Using a baseline exposure of F1.0 and a shutter speed of 1 second as "EV0," each increase in EV (EV1, 2, 3, etc.) indicates an increase of one level (setting) in either aperture or shutter speed.

Exif

Abbreviation for Exchangeable Image File. This digital camera image data format allows thumbnails and photo-related information to be stored in the header of image files. Photo information includes time, date, camera name, focus distance, aperture, shutter speed, exposure, white balance and more. This information can then be read and displayed by "exif-aware" image processing programs.

Exposure

The amount of light that strikes the image sensor or film. If the exposure period is too long, the image is "overexposed" and if it is too short, the image is "underexposed."

Exposure Compensation

Depending on the subject's degree of reflectance or lighting condition, AE photography can easily produce exposures that are either over or under the optimum. To compensate for this type of error, plus or minus compensation can be added to correct the exposure, which is called exposure compensation.

Exposure Meter

A device that measures the amount of light shining on the subject to determine the correct aperture and shutter speed. Exposure meters are either built into the camera or hand held.

Exposure Zooming

A special photographic effect where a zoom lens is zoomed during the exposure, thereby changing the focal length. The resulting image has streams of light radiating out from the center of the lens to the periphery.

Extension Ring

Also known as an extension tube, it is inserted between the camera and the lens and changes the focal length of the lens. For example, it can change a 200mm lens to a 400mm lens, thereby improving the close-up performance.

back to top

F

False Colours

Images taken by a digital camera are sometimes affected by false colors, due to moire patterns, which are not originally included in the subject. These occur more often in subjects that have fine details. False colors are generated because the image sensor uses the light amounts that enter it from each part of the image, after passing the light for each pixel through a color filter. It converts these light amounts into electrical signals to reproduce the image. Digital cameras sometimes provide a low-pass filter in front of the image sensor to prevent false colors.

File Extension

Identifies the type of data file. Located on the right side of the period following the filename, the extension consists of three characters. For example, a JPEG file would have the extension ".jpg".

Fill

Any kind of supplemental light used in a photograph, e.g., a reflector or a daylight synchro flash.

35mm Format

A common photographic term referring to the SLR camera format using 135 cartridge film. Although the width (gauge) of the film strip is 35mm, the size of the exposed frame is 36 x 24mm. Not to be confused with 35mm film - motion picture format, where although using the same gauge, the film frames run vertically through a movie camera or projector at 24 frames per second.

35mm Film

The most popular type of roll film. Measuring 35mm wide, the film strip runs horizontally and has small perforations on top and bottom that mesh with the camera's film winder gears. Popular types include black and white, colour, and slide film, and are produced in a variety of light sensitivities depicted by ASA or ISO ratings.

Film Speed

A standard created by the International Organization for Standardization, or ISO, designed to show a film's sensitivity to light, e.g., "ISO400." When the ISO number increases, the film's sensitivity to light also increases, and as it decreases the film's sensitivity decreases.

Filter

Usually attached to the front of a lens, a wide variety of filters are available, including UV filters that regulate light and cut UV, color filters, polarizing filters, cross filters, and rainbow filters.

Fine-Particle Film

Film consists of ultra-fine particles (silver halide crystals, dyes, etc.) that when exposed to light produce an image. These particles are especially small or fine in low-speed film, which gives images an added dimension of clarity and detail

FireWire

Popular interface standard for connecting PCs and peripheral devices. Allows 400-Mbps high-speed data transfer. "FireWire" is the name used by Apple Corporation and is identical to IEEE 1394. It is also called "i.Link."

Fisheye Lens

A special lens that provides about a 180- degree field of view. In order to capture all 180 degrees in a single image, the picture will become distorted into an ellipse, like when looking through the peephole in a door.

F-stop

Indicates the aperture value. Commonly used f-stops include F2.0, F2.8, F4.0, and others. Smaller values indicate that a larger amount of light is allowed to enter the camera. As the value increases, the aperture becomes smaller, reducing the amount of light entering the camera.

Fixed Lens

A lens with a single focal point, or basically any lens that is not a zoom lens. Fixed lenses are more compact than zoom lenses and generally offer high performance in rendering images.

Fixed Lens Camera

Today, these are primarily disposable and low- price compact cameras, although the term includes any camera that does not have a focusable lens.

Flash Range

Describes the distance that can be accurately metered by an automatic flash unit. As a film's sensitivity to light decreases (the ISO number becomes smaller), this range becomes narrower, and as it increases, the range expands. Similarly, opening the aperture wider expands this range, while stopping the aperture down narrows it.

Flash Unit

A lighting unit designed to fire the instant that the camera's shutter is opened. Also known as a strobe or a speedlight. Many digital cameras are equipped with flash units and use the feedback of an onboard sensor to control the flash exposure value.

Flat

A term that describes an image with very low contrast, either on film or photographic paper, giving it the impression of minimal depth.

Focal Length

The distance from the middle point of the lens to the focus point. Assuming that the camera's position is fixed, the larger this value becomes, the larger the subject appears (telephoto). Conversely, the smaller this value becomes, the smaller the subject becomes (wide angle).

Focal Plane Shutter

Describes a shutter located directly in front of the focal plane. Placing the shutter directly in front of the focal plane allows lenses to be easily changed.

Focus

The point where rays of light from a lens converge to form a sharp image.

Focus by Eye

A focus method where the photographer estimates the distance to the subject by eye, then uses the distance numbers engraved in the focus collar to set the distance.

Focus-Priority AF

A type of autofocus mode. Pressing the shutter button starts the autofocus distance calculation and when focus is taken, the shutter is fired.

Focusing Screen

Used for focusing on a subject or composing a picture, this matte-like screen is located equidistant to the film plane. Interchangeable on some models of single lens reflex cameras.

Foreground Focus

Placing the portion in front of a subject in focus is called foreground focus. This can give depth to scenes that would otherwise appear flat and monotonous.

Frame Aberration

When a ray of light passes obliquely through the lens and distorts the image in a vertically non-symmetrical manner rather than collecting at a single point.

Framing

Refers to the composition of a scene's subject and background regarding positioning, balance, etc. Framing, i.e., deciding which elements to use and which to hide, is one method the photographer uses to create the desired image.

Front Light

Light striking the subject from the front. While brightly illuminating the subject and removing shadows, front light can also make the subject appear flat and uninteresting.

Front Focus

The opposite of back focus, front focus is where the camera is focused on a point in front of the subject. While doing this intentionally may be useful at times, this term is most often used to describe a mistake.

Full Aperture Metering

When metering using a TTL exposure camera, full aperture metering will select the correct shutter speed even if the f-stop is at its maximum aperture (i.e., wide open).

back to top

G

GB (Gigabyte)

Unit of data measurement. 1000 times larger than 1MB (1000MB = 1GB).

GIF

One type of image file format. File sizes are typically small, hence .gif images are often used on Web sites.

Glare

Light from the lens that reflects into either the camera mirror's prism or the camera's metal chassis. This can result in extra light striking the film or image sensor, halation, reduced contrast and/or dull colours.

Gradation

The levels of color, from pure white to pure black. Gradation is said to be attractive if many levels are used and the transition from one level to the next is smooth and even. The word "tone" is used with the same meaning.

Guide Number (GN)

A value used to calculate the exposure of a flash unit or light source. Also used as a criterion to describe the intensity of a flash or light source. A guide number of "1" is appropriate for ISO100 film at a distance of one meter.

back to top

H

Halation

Halation, which occurs with backlighting or partial backlighting, is caused by light reflecting off the front surface of the lens to cast a whitish fog onto the image, or light passing straight through the film's emulsion and being reflected back by the film base on the light sensitive layer.

Half Size

A standard film size (17 x 24mm) that is about half the size of a single frame of 35mm film (36 x 24mm). This allows approximately twice as many pictures to be taken as a roll of 35mm film. Also called "cinema size," since movie film was originally this size.

Halftones

Images reproduced using shades between black (shadow) and white (highlight). The finer the halftone gradation, the richer the image's shading.

Hand-Shake

The term for moving (shaking) the camera at the instant the shutter is opened, which will blur the image.

High-Speed Film

Generally speaking, any film that is faster, i.e., more sensitive to light, than ISO100. Currently, ISO400 is the most popular type of film and "super-high-speed film" (ISO1000 or faster) is often used when photographing fast- moving subjects or subjects in shadow.

High-Speed Shutter

A high-speed shutter enables shutter speeds of 1/250th of a second or faster. These fast shutter speeds allow you to freeze moving subjects and enjoy unique photographic effects.

Histogram

A graphical representation of the range of light in a scene, from the lightest point to the darkest point. Histogram data is typically displayed on a monitor, such as a digital camera's LCD monitor, electronic viewfinder or on a PC. This allows the photographer to check for blow-outs in highlights and blocked shadows.

Hot Shoe

Equipped with a flash contact, this device allows the attachment of a clip-on type flash unit.

back to top

I

IEEE 1394

Popular interface standard for connecting PCs and peripheral devices. Allows 400-Mbps high-speed data transfer. Referred to as "FireWire" by Apple Corporation. It is also called "i.Link."

i.Link

Name for a digital video (DV) camera's DV terminal. Identical to IEEE 1394 and FireWire.

Image Circle

The diameter of the circle of light created as light passes through the circular lens and strikes the image sensor or film. The film or sensor records only the rectangular portion of this image.

Image Pixel

A digital image is simply a collection of tiny squares or points. These points are called image pixels or pixels. When talking about a CCD's image pixels, they refer to the smallest element of that device.

Image Sensor

Converts the light intensity that passes through the lens into corresponding electrical signals. Typical examples are CCD and CMOS image sensors.

Image Size

Describes the size of a digital image using the number of pixels it contains. Image size depends on the number of image pixels in the camera's CCD. For example, the largest image that a 2,000,000-pixel (2-megapixel) camera could produce would be 1600 x 1200 pixels, and the largest image a 3-megapixel camera could produce would be 2048 x 1536 pixels.

Incident Light Metering

A method of metering that measures the amount of light striking the subject. The measurement is taken by standing in front of the subject and facing the light source. In contrast, a camera's built-in exposure meter uses "reflective light metering" and measures only the light reflected from the subject.

Incidental Light Angle

Represents the angle of light entering a light meter. A simple light meter (especially a reflective light meter) will always display this angle.

Infinity

Used to mean an infinitely far distance. Indicated on a lens by the infinity symbol (∞). Infinity is normally considered as beginning 200 or 300 meters from the camera.

Infrared (IR) Film

A special black and white film that is sensitive to normally invisible infrared light (thermal rays). In IR photos, green leaves look bright, skin tones have a translucent appearance, and blue skies turn dark. The entire scene is high in contrast.

Inkjet Printer

Sprays picoliter-sized drops of ink onto paper to produce an image. These home-use printers allow you to easily produce beautiful photo- quality prints.

Interpolation

Allows the manipulation of a digital image (expand, reduce, rotate, etc.) by inserting quasi-pixels between actual pixels in order to preserve as much as possible the quality of the original.

ISO (Sensitivity)

A value used to indicate a film's sensitivity to light. ISO also stands for the International Standards Organization. Since no similarly defined standard exists for digital cameras, the term "ISO100 equivalent" is used. A larger ISO value indicates that the camera can take a better picture in dimly lit locations (such as indoors).

back to top

J

Jaggies

One type of degradation found in digital images. Often described as zig-zag lines in hairlines or in the edges of highlights.

JPEG

JPEG is an abbreviation for the Joint Photographic Experts Group, and stands for a highly efficient algorithm for compressing images. The file extension".jpg" indicates that this algorithm was used for an image's file format. Widely used in digital cameras. This compression cannot be reversed and, as a result, using a high level of JPEG compression will reduce image quality due to the creation of noise.

back to top

K

K (Kelvin)

A value used to indicate the color temperature of light.

KB (Kilobyte)

A unit of data measurement (1024 bytes = 1KB).

Key Light

The source that provides the majority of the light striking the subject. Also called main light.

back to top

L

Lab

Short for laboratory, a place where film is processed.

Large-Format Camera

A camera that shoots 4" x 5" or larger film. Other popular film sizes are 5" x 7" and 8" x 10." Film for these cameras is loaded one frame at a time into a film holder and then shot.

Latitude

Indicates the amount of exposure tolerance of a film. This tells the degree to which exposure can be varied from the specification and still produce an acceptable image. Generally speaking, the latitude of negative film is wide and that of reversal film is narrow.

LCD Monitor

A liquid crystal type of display screen. Common types of digital camera LCD monitors are MIMs, TFTs, and polysilicon TFTs.

Lens Mount

A metal device used to attach the lens to the camera body. Found on cameras with interchangeable lenses (single lens reflex, etc.). Each camera manufacturer uses their own design mount, and with only a few exceptions they are not interchangeable.

Lens with Shutter

The shutter mechanism is included inside the lens, hence the name. Many large-format cameras use this type of lens.

Light Balancing (LB) Filter

A colour correction filter designed specifically for use with standard colour film in daytime or with a flash. While use in these situations produces well-balanced colours, use of an LB filter on a cloudy day will produce blue-green colours and with sunrise or sunsets will produce reddish colours.

Light Intensity

In basic terms, the amount of light in a scene. Can be said to be large or small. Used not only to describe natural light, but artificial (flash) light as well.

Light Source

The source of the image's light. On a sunny day this is the sun, and in an enclosed room it is an artificial source, such as electric lighting or a flash.

Lithium Battery

A popular type of battery that provides optimal discharge voltage for operating a digital camera (e.g., to provide flash power, display data, zoom the lens, etc.). This battery's advantages include superior power storage, long life (5 to 10 times longer than manganese batteries) and the ability to operate even at -40°C.

Low-Key Shooting

A technique that deepens an image's colors and lightens shadows. Similar to underexposing, the single difference is the introduction of highlights in dark tones.

Low-Pass filter

This is a filter that is positioned directly in front of the image sensor to prevent the generation of false colours. It cuts out the frequency components that are easily subject to false noise and allows only lower-frequency components to pass through.

Low-Speed Film

Films less sensitive than ISO100. Of these, ISO50 is the most popular. These films provide extremely detailed images. However, they require a slower shutter speed, which can lead to blurring in hand-held photos.

back to top

M

Macro Lens

Specially designed to magnify a subject. Often used for photographs of small subjects, such as insects or flowers. Captures a large amount of detail, and at close distances magnification of 1/2 or more is possible.

Macro Photography

Also called a close-up, this refers to photographing subjects at close range. It often brings out normally unseen details or perspective.

Main Light

Also called a "key light," this is the primary source of a scene's light. A main light is usually directed at the subject from an angle (plane light), or from the front (front light). The antonym for main light is "fill light."

Maximum Aperture (F-Stop)

The smallest f-stop value for the lens (maximum brightness). Expressed as, for example, "F2.8" or "1:2.8," the smaller this value is, the brighter the lens is. With a zoom lens, a value of "F2.8–4" indicates that the maximum aperture will vary from F2.8 to F4.0, depending on the focal distance.

MB (Megabyte)

A unit of data measurement that is 1000 times larger than 1KB (1000KB = 1MB).

Medium-Format Camera

Any camera that uses Brownie film (120 or 220). Very high-quality prints are possible from Brownie negatives, since they are considerably larger than those produced by 35mm film.

Megapixel

The term for one million (1,000,000) pixels.

Memory Stick

A removable flash memory card launched by Sony. Memory Sticks are available in two types — Memory Stick DUO and Memory Stick PRO.

MF

Abbreviation for Manual Focus. Whereas AF indicates the automatic focusing of the lens, "MF" indicates the focusing of the lens by hand (manually).

Middle-Distance (Intermediate) Lens

Lenses with an angle of view between that of "standard" and "telephoto" lenses. With 35mm cameras, any lens with a focal length in the range of 70mm to 120mm is called a middle- distance lens.

Mirror (Reflecting) Lens

A lens that uses a mirror in the first lens element. This type of lens is typically small, lightweight, and has a low level of chromatic aberration.

MO

An abbreviation for Magneto-Optical disk, a type of data storage device that uses a combination of both laser light and magnetism. This external storage device is used to store digital image data and is approaching the popularity of CD-R/RW drives.

Moire

Often appears in images containing fine striped or lattice patterns. These patterns can conflict with a CRT monitor's pixels or a printer's dot array, resulting in rainbow- colored or spiral patterns.

Motion Blur

When photographing moving subjects, motion blur helps give the actual feeling of movement. Using a slow shutter and other techniques can transmit the feeling of motion by blurring movement and giving the background a flowing look.

Motor Drive

A device used to drive the film feed and charge the shutter. Especially useful in continuous shooting mode, motor drive provides a rapid burst of pictures to capture fast-moving subjects.

MPEG

Standard for the compression and expansion (playback) of digital video, with MPEG1 and MPEG2 being the most widely used formats. Many digital cameras also use MPEG1 format when recording video.

MP3

Abbreviation for "MPEG Audio Layer 3." This is a popular format for digital audio compression. It compresses audio data to 1/10th its original size, while providing relatively high-quality music reproduction.

Multi-Flash Synchro

The simultaneous use of two or more flash units. This is used to both make the image look realistic, i.e., to prevent the lighting from becoming "flat," and to provide additional synchronized flash light when a single flash is insufficient.

Multiple Exposure

Two or more exposures on the same frame of film or image. With a film camera, multiple exposures are created by repeatedly opening the shutter, without advancing the film. They can also be created in the darkroom by exposing a single piece of photographic paper to multiple negatives.

Multi-Zone Metering

A metering method where the screen is divided into numerous areas and exposure data received from each area is used to calculate the image's overall exposure settings.

back to top

N

Negative

Film in which an image's light and dark areas are reversed. Negative film is used to print photographs.

ND Filter

Abbreviation for Neutral Density Filter. Attached to the front of the camera's lens, it reduces the amount of light entering the lens. When light levels are strong, such as when outdoors in sunshine, attaching an ND filter allows you to use both your maximum aperture and slower shutter speeds.

No Trimming

Printing an image exactly as it appears on the negative, with none of the image being cut from any side.

Nyquist Frequency

The Nyquist frequency is the limit of resolution for the image sensor. It is 1/2 of the pixel pitch (the value obtained by dividing the length of the long side of the image sensor by the number of horizontal recording pixels).

back to top

O

Oblique Light

Light that falls on the subject from a front angle. It is used to give the subject added contrast and definition by expanding highlights, since it provides greater brightness than side lighting, and by adjusting shadows.

Optical Viewfinder

Except for the period that the camera's shutter is open, an optical viewfinder is a window that shows what the camera "sees." In a film camera, it is simply called the viewfinder. With a digital camera, however, since its rear-face LCD monitor can also be used as a viewfinder, the term "optical viewfinder" is used.

Optical Zoom

As the focal length of a zoom lens is changed, the subject is magnified. When an image is magnified via the lens, the resulting image looks natural.

Out of Focus

Any subject or area that is not in focus.

back to top

P

Pan Focus

Describes when all of the items in a scene, from the background to the foreground, are in focus. This is easier to achieve with wide-angle lenses.

Panning

The technique of following a moving subject's direction and speed by swinging the camera so that the subject remains in the same relative position in the viewfinder as you take the picture. The resulting image will have the subject frozen and the background blurred, which accentuates the feeling of speed and motion.

Parallax

The term used to describe the difference between the range of view seen in the camera's viewfinder and the range of the actual photograph. This difference occurs in cameras with separate viewfinders and lenses, and increases the closer the subject is to the camera.

Passive AF

An auto focus system that optically ranges (measures and calculates) the subject image distance. Unlike active AF systems that send out beams of light, such as infrared, laser, etc., with this system the camera is passive, hence the name.

Patrone

Introduced by Kodak, Patrone, or 35mm film as it is now commonly known, is wound tightly in a completely light-proof metal container, called a cartridge. On the surface of the cartridge is printed its sensitivity setting, known as the DX code.

PC Card Adaptor

Inserting this adaptor into the PC (PCMCIA) card slot of a personal computer allows you to then insert your digital camera's memory card into the adaptor and transfer image data to your PC.

Perforations

Located on both sides of 35mm film, these small holes are used by the camera's winding mechanism.

Peripheral Light

Lenses tend to be bright in the center and darker towards the edge. The amount of light found at the lens edge is called peripheral light. Lenses with a protruding front element, such as a wide-angle lens, have a comparatively large amount of peripheral light. However, wide-angle lenses used in rangefinder and similar cameras usually have slightly less peripheral light.

Photographic Exposure

The amount of light that passes through a lens (either a camera or photographic paper) to form an image. Light is controlled via the shutter speed and the aperture and the term exposure is commonly understood as having the same meaning, i.e., the reception of light.

PICT

The standard image format used with Macintosh computers.

PictBridge

This standard makes it possible to connect a digital camera directly to a printer for printing, without having to use a PC.

Pinhole Camera

As the lens aperture becomes smaller, depth of field increases (deepens). If the aperture is reduced to the size of a pinhole, the entire image will be in perfect focus even without using a lens. This is the design principle behind the pinhole camera.

Pixel

Synonymous with an "image pixel" or a "dot," "pixel" is used to describe the smallest element (square) of a digital image. Often used to describe imaging device resolution, such as for displays, etc.

PL (Polarizing) Filter

Abbreviation for polarizing filter. Attaching a PL filter to your camera lens not only cuts glare from the surface of glass and water, it also helps to deepen the color of blue skies or autumn leaves.

Portrait

So many portraits of female models have been taken that a portrait has become synonymous with a picture of a woman.

Positive

Making a positive image directly from film exposed in the camera to reproduce a subject's shading, i.e., light and dark.

Pre-Focus

Used when photographing moving subjects. The photographer decides on a pre- determined point where the subject will pass and pre-focuses the lens on that point. When the subject passes, the photographer simply presses the shutter.

Primary Colour Filter

A filter that uses the primary colours (red, green and blue) to ensure the correct extraction of colour information from the CCD. It is generally assumed that the use of this filter on a digital camera makes it easier to create vivid, rich colour images.

Profiles

Profiles are files that contain information on the colours that can be reproduced by digital cameras, monitors, printers, scanners, etc. They make it possible to unify the different colours reproduced by each piece of equipment. (See Colour Management.)

Program AE

A mode where the camera automatically calculates the combination of aperture and shutter speed that will properly expose a scene

back to top

Q

QuickTime

A popular, easy-to-use multimedia software developed by Apple Corporation. Supports a wide variety of file types and can play back video, sound and image data.

Quick-Release Plate

When using a tripod to take a photograph, the camera is normally attached (screwed in) or clamped directly to the tripod's head. A quick- release plate is designed to quickly attach the camera to, or release the camera from the tripod head. This, in turn, allows two or more cameras to be quickly changed on the same tripod, as well as allowing the tripod to be easily moved.

back to top

R

Rangefinder Camera

A camera with a rangefinder (a distance meter) built in to the body. The photographer focuses this camera by rotating a distance ring on the lens. Some of the best-known rangefinders are Leica's M-Series cameras.

RAW Format

A name for data read directly from the CCD, that has only been converted from analog to digital. Data output in this format is in its original state, i.e., it has not been processed internally by the digital camera.

Real-Image Viewfinder

In contrast to a virtual image type, a real- image optical viewfinder sends light through the actual imaging point. Widely used in compact cameras, especially those equipped with zoom lenses.

Recording Media

The storage medium used to record an image. Functionally equivalent to film in a silver halide film camera. A wide variety of media can be used, such as memory cards (SD, Compact Flash, Memory Stick, etc.) and disk media (floppy, CD-R/RW, DVD-RW, etc.).

Red-Eye

Reflection of flash light from the eye's blood vessels that gives the appearance of having red pupils. Often occurs when shooting outdoors in a dimly lit location, when the subject's pupils are dilated (opened). To prevent this, a series of pre-flashes from the flash unit constrict the subject's pupils before the flash is fired.

Reflective Light Meter

Reads the amount of light reflected from the subject. All built-in camera light meters are the reflective type.

Reflective Light Metering

A type of metering that measures the light reflected from the subject. One advantage of this method is the ability to obtain an accurate reading even when the subject is far away.

Reflector

One means of using reflected light to brighten a darkened portion of a subject. Widely used in portrait and other types of photography, it is an easy way to add additional light. While highly reflective, light from gold and white reflectors do not change the colour of the primary light

Relative Aperture

The ratio of the available aperture and the focal length. The smaller this ratio, the larger the available aperture and the brighter the lens.

Resolution

Indicates the ability of a device to resolve detail. Most often used with lenses, it can also be used with monitors and printers.

Retouching

Modifying digital images using a PC and image editor software. Typically involves adjusting the image's tone, contrast and brightness, and removing unneeded sections of the image. Previously, film retouching required a professional who performed all modifications by hand, but now, with just a PC anyone can easily edit their digital images.

Reversal Film

Unlike negative film, which reverses the colors of the actual scene, this film records a scene's colors exactly as they are. Also known as slide film or positive film.

Rewinding Film

The process of rewinding all exposed film from the take-up reel to the film cartridge. Recently, most cameras perform this process automatically.

RGB

The three primary colours in light: red, green and blue. PC monitors use the RGB colour model to display colour.

Roll Film

Film that comes in a roll and is protected from light by a length of paper wound around the film. Can be loaded into a cartridge (a Patrone), which allows the film to be easily changed, even in daytime.

back to top

S

SD Memory Card

A next-generation memory card that is the size of a postage stamp. The SD Memory Card has data security and write protect features.

Segmented Metering

A metering method wherein the camera compares and calculates the exposure of a series of pre-divided scene areas to calculate the optimal exposure for the scene.

Self-Timer

An automatic feature that provides a delay after the photographer presses the shutter until the shutter actually opens, to allow the photographer to take a self-portrait or pose in a family or group picture, and to reduce hand- shake.

Sensitivity

Indicates the degree of sensitivity of a given film or image sensor (CCD) to light. Film normally uses ISO values to indicate the level of sensitivity. With digital cameras, the sensitivity of the CCD can be set using ISO- equivalent values.

Shadows

Areas in a scene that are dark, i.e., areas not exposed to light, are called shadows. The opposite is a highlight. Since subjects usually contain both shadows and highlights, the image's exposure is decided according to which area the photographer wishes to see or use.

Sharpness

Expresses lens quality. Skillful balancing of the lens resolution and contrast increases sharpness. Film sharpness is also decided based on the balance of resolution and contrast.

Shutter

One of the camera's most important mechanisms, the shutter controls the light exposure by opening for a precisely determined time and then closing. With film cameras, it can be a piece of black cloth or articulating steel in the center of the film chamber. It is designed to prevent light from striking the film surface while the shutter button is not pressed, and to regulate the amount striking the surface when the shutter button is pressed.

Shutter Button

Used to activate the shutter, this button is also known as the shutter release button (or release button).

Shutter Half-Press

Most cameras equipped with AE and auto- focus also have a 2-level shutter button. The first, or half, press measures and sets the scene's exposure value and subject distance. Pressing the button down completely then activates the shutter.

Shutter Priority AE

Here, the photographer sets the shutter speed and the camera automatically calculates and sets the correct aperture. High shutter speeds can be used to freeze moving subjects, and slow shutter speeds can create a motion blur that exaggerates the feeling of movement.

Sidelight

Light striking the subject from the side. Sidelight accentuates dark and light areas, and gives the subject a 3D feeling. However, depending on the subject, it can also produce excessive shadows.

Silver Halide Photograph

Currently the most popular type of film for taking pictures. Since silver is the principal element in this film, the term "silver halide" has become a popular term for describing this film.

Slow Shutter

Any picture taken at a shutter speed of 1/30th of a second or slower. A slow shutter allows the use of various effects, such as blurring a waterfall's fast-moving water to express its flowing motion.

SLR

Abbreviation for a single-lens reflex camera. A single lens is used for both the viewfinder and for image capture.

Smart Media Card

A compact semiconductor media based on flash memory. Its simple design, consisting of a base resin and a memory chip, makes it thin and light. The card contains no control circuit, instead using circuitry in the card adaptor or digital camera.

Smear

Streaks of light entering the image from the sun or other strong light source. Peculiar to digital cameras, smear is caused by the light sensitivity of the CCD immediately after the shutter is opened.

S/N Ratio

Abbreviation for Signal-to-Noise Ratio. Represents the ratio of noise to image data. If an image's signal-to-noise ratio is high, it means that the image's noise level is low.

Soft Focus

A method of softening highlights and other bright areas to give a scene a gentler, more delicate tone. Soft focus lenses and filters can be used to produce this effect.

Soft Focus Lens

Used to give an image or scene a soft, gentle mood. Since these lenses are designed specifically to produce a controlled softness, spherical aberration is left uncorrected. Typically the center of the lens provides a clear image while peripheral aberration creates a gentle, halo-like diffusion of light, which in turn gives the image its soft, delicate tone.

Soft/Hard Tone

Describes the look of a printed image. The contrast between light and dark is either too low, or too high.

Special Digital Lens

These lenses are developed to match the characteristics of the image sensor. They are characterized by telecentricity, comprehensive aberration correction, lens coatings that prevent ghosts and flaring due to specular reflection in the image sensor, and a size that matches the image sensor.

Special-Effect Filters

Light striking the front of these filters is either reflected or refracted, and is intended to alter the look of an image. A wide variety of special- effect filters are available, including cross and rainbow filters.

Spot Meter

Designed specifically for metering within a very narrow range. Used to closely meter a single portion of a subject.

Spot Metering

Uses a small point in the center of the screen to meter exposure. Useful in many situations, such as when the subject and background have extreme light and shadow differences, such as with stage or back lighting.

sRGB

Abbreviation for Standard RGB. sRGB is the international color space standard created by the IEC (International Electrotechnical Commission). Performing all color adjustments in this color space minimizes colour disparities from input and output data collected via PC peripheral devices, such as digital cameras, printers, and monitors.

Standard Lens

A lens with the focal distance that is closest to the field of vision of the human eye, which is approximately 50mm.

Standard Reflective Ratio (Neutral Grey)

When measuring the amount of light reflected by an object, normally pure white reflects 90% of the available light and pure black reflects 3%. Calculating the geometric average of these values gives the value of 18%. This value is referred to as the standard reflective ratio and provides the exposure calculation standard for the camera. Also known as neutral gray.

Star Noise (Blooming)

When using a digital camera for timed (long) exposures, heat can build up on the CCD or other photoreceptor, creating star-shaped noise. Also called "dark noise."

Stationary Lighting

Any type of continuous lighting. The opposite of flash lighting.

Subject Distance

The distance from the camera to the main subject. When shooting a subject with the same focal length lens, if the subject distance becomes close (short), the shot is a close-up and the subject becomes large. Conversely, if the subject distance becomes far (long), the subject will become small.

Submersible Housing

Used by underwater photographers, this specially designed camera case protects the camera from moisture. An optical lens is placed in front of the camera lens, and O-ring seals are attached to all moveable case parts (levers, buttons, etc.), allowing the photographer to use all of the camera's functions while submerged.

SVGA

Abbreviation for Super Video Graphics Array. Resolution is 800 x 600 pixels. One of the standard PC display modes.

SXGA

Abbreviation for Super eXtended Graphics Array. Resolution is 1280 x 1024 pixels. This resolution is a vertical and horizontal expansion of XGA (1024 x 768 pixels).

Synchro Contact (Hot Shoe)

A contact that synchronizes the shutter and flash light. Many high-end digital cameras are equipped with this contact, which allows the use of a synchronized external flash.

back to top

T

Telecentricity

This is a lens property that allows straight beams of light perpendicular to the image sensor to be received. Image sensors are not sufficiently sensitive to light that enters at an angle. Because of this, telecentricity is an important property for digital camera lenses.

Telephoto Conversion Lens

A lens that attaches to the rear of another lens to increase its focal length. Allows the photographer to take photographs at longer distances.

Telephoto Lens

Among 35mm camera lenses, those with focal lengths of 70mm or longer are called telephoto lenses. Lenses with a focal length of 400mm or longer are called super telephoto lenses.

Thumbnail

Small images, such as those on a digital camera's display or a PC, that give a preview of a larger image. They allow data to be easily checked or stored/cataloged.

TIFF

One of the common image file data formats, like JPEG and GIF. This format does not compress image data and is a standard feature in most digital cameras. While TIFF format produces very high-quality pictures, the files are very large.

Time Lag

This refers to the time that is required before you can press the shutter button after first turning on a digital camera, and also to the time required for the shutter to actually open after the shutter button is pressed.

Tone Curve

This is a curved line graph that expresses the change in density between input and output. A condition with no change in density is shown by a straight 45-degree line. Brightness and contrast can be adjusted by shifting that line or giving it a curve. This is one of the functions of image processing software.

Top Light

A light positioned over the subject. It is used mainly in studios to highlight a subject's hair and prevent it from merging into a black background, or to emphasize the top surface of a product.

Top-Face Controls

A common term for the film advance lever, shutter speed dial and other controls located on the top of a camera.

Transmitted Light

Backlighting or other light that passes through the subject. Transmitted light can be used, for example, to create transparency and vivid coloring in glass, a flower petal, or a leaf.

Tripod Head

Attaches to the top of a tripod's legs and secures the camera in place. "Pan" and "ball" type heads allow the camera to be set at any angle.

TTL Metering

Abbreviation for "Through The Lens" metering. This system meters light that enters the camera through the lens. Since TTL uses the same light that will strike the film, the exposure taken will always be correct regardless of the lens or filter that is used.

Tungsten Film

A colour temperature of 3200 to 3400K allows this film to correctly reproduce colours in scenes containing tungsten lighting. Useful in various situations, especially those with electric lights.

Tv

A value used to represent shutter speed.

back to top

U

Underexposure

When the exposure used is less than the correct value, the image will appear dark and is said to be underexposed.

Unsharp Mask

A tool often found in image editing software. Increases contrast at image edges and enhances the visibility of a boundary between light and dark tones which helps improve image clarity.

USB

Abbreviation for Universal Serial Bus. One standard used for the transfer of data from peripheral devices to the PC. This convenient system allows the hot-swapping of connectors and the connection of up to 127 devices to a single USB port.

USB2.0

High-speed 480-Mbps data transfer interface. Approximately 40 times faster than USB1.1 (12 Mbps).

UV Filter

A filter designed to cut UV (ultraviolet) light. Also used as a lens protection filter.

UXGA

Abbreviation for Ultra eXtended Graphics Array. Resolution is 1600 x 1200 pixels. This resolution is a vertical and horizontal expansion of XGA (1024 x 768 pixels).

back to top

V

VFZ

Abbreviation for Vector Format for Zooming. This next-generation digital image format uses lossless compression to save an image at 2/3 its original size. Unlike standard digital compression, which makes it difficult to reuse data, this format allows the easy enlarging and reducing of data, with no loss in quality.

VGA

Abbreviation for Video Graphics Array. A graphics system developed by IBM. Resolution is 640 x 480 pixels and uses 16 colours. Widely used as a standard for PC graphics systems.

Vignetting

Due to the limited size of the lens opening, light that enters at an angle as viewed from the image plane is blocked and the perimeter of the image becomes dark. This is vignetting. When a point light source around the image is blurred, the vignetting sometimes appears elliptical rather than round.

Viewing Angle (also called Angle of View)

Indicates the viewing range to be photographed. To calculate this angle, take a diagonal line out from the front of the lens to show the extreme visible edge, and another line directly out, in line with the lens. This angle will change, depending on the focal length of the lens.

Viewfinder

Allows the photographer to confirm the image's viewing angle, which in turn allows adjustment (trimming, etc.) of the image's layout and composition.

Viewfinder Coverage

The ratio of the area visible through the viewfinder, versus the area captured on film. Film coverage is set to 100%, and viewfinder coverage is expressed as a percentage of that. Some SLR camera viewfinders cover 100% of the film area (the average is from 90% to 97%). Most compact camera viewfinders cover about 85%.

back to top

W

WAV

The file extension (.wav) for standard Windows PC sound format files.

Web

Stands for the World Wide Web (www). Derived from the idea of a spider web. Now often refers to the network itself.

White Balance (WB)

Provides color temperature correction when taking photographs at different times on a sunny day, or in different types of artificial lighting. While differences exist between Auto WB and Manual WB types, this feature is found on every digital camera.

Wide-Angle Lens

Describes any lens that provides a wider angle of view than a "standard" lens. With a 35mm camera, that means any lens with a focal length of less than 35mm can be called a wide-angle lens. Similarly, any lens with a focal length of 24mm or less can be called a super wide-angle lens. Often the distortion inherent in these lenses can be used to produce interesting and unique images.

Wide End

The widest angle of a zoom lens, or simply, the zoom's shortest focal length.

Winding (Advancing) Film

Moves the currently exposed image (photograph) to the take-up reel and brings the next, unexposed piece of film into position.

Wrong Focus

When the subject is not in the center of the image, auto focus systems tend to focus instead on the background, which is in the center of the frame, causing the subject to blur.

back to top

X

X Contact

A contact used to synchronize a flash connected to a camera. "X" is an abbreviation of Xenon, which is the gas used in the flash element.

xD Picture Card

Measuring just 20mm x 25mm x 1.7mm, this memory card is the smallest in the world and can hold large amounts of data.

XGA

Abbreviation for eXtended Graphics Array. Resolution is 1024 x 768 pixels. One of the standard PC data display modes.

back to top

Z

Zone Metering

A method of metering in a narrow or confined space. Measures an area wider than spot metering.

Zoom Flash

A type of flash that allows the illumination angle to be changed.

Zoom Ratio

The ratio of the longest focal length value of a zoom lens to its shortest focal length value. For example, the zoom ratio of a 35mm to 105mm lens is 3x.

Zooming

Using a zoom lens to bring distant objects close-up from a fixed position by focusing from wide angle to telephoto, or conversely, zooming out from telephoto to wide angle.

back to top
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z