Photographic Glossary-E


Chemical processing system for most colour-reversal (slide) film. Kodak's standard chemical process for developing Ektachrome or compatible slide films from other films makers apart from Kodak.

A device to hold photographic paper flat during exposure, usually equipped with an adjustable metal mask for framing. A holder to keep sensitized material, normally paper flat and in position on the baseboard of an enlarger during projection printing. It usually has adjustable borders to frame the image to various size.

Extra Low dispersion - usually refer to glass type. Glass with ED properties indicating special rare earth glass or special formulated glass that limiting or correcting of light rays passing through the lens elements to achieve all spectrum of colours to falls on the same plane of focus - especially the Red and Blue spectrum and is usually more apply to longer focal length lenses where the problem is more serious. First popularised by Nikon's Nikkor lens line - with a gold lining in the front part of the lens. Pentax, Olympus use the same name as Nikon. Canon's version is called "LD" - with red lining and usually their lenses are white in color. While Minolta uses APO. Independent lens makers, like Tamron, uses LD, Sigma uses APO, Tokina's version is SD APO; all these trade names are basically performing the same functions.

Edge numbers
The reference numbers printed by light at regular intervals along the edge of 35mm and roll films during manufacture.

Effective aperture
The diameter of the bundle of light rays striking the first lens element that actually pass through the lens at any given diaphragm setting.

Effective resolution
The final appearance of a scan that has been enhanced to produce more data than the scanner can record. This is done by interpolation.

see exposure index

Electronic Image Stabiliser. Feature that minimises effect of camera shake. Originally designed for video cameras. Canon has transfer the technology over to its EF lenses, we expect more Canon's EF lenses will adopt this feature.

EISA bus
Eisa is a standard bus ( computer interconnection ) architecture that extends the ISA standard to a 32-bit interface.

Electronic display
Showing images through the computer.

Electronic Document
A document that has been scanned, or was originally created on a computer. Documents become more useful when stored electronically because they can be widely distributed instantly, and allow searching. HTML and PDF are well known electronic document formats

Electronic flash
A small device usually built into digital cameras that emits a brief burst of light to illuminate poorly lit scenes. Light source based on electrical discharge across two electrodes in a gas-filled tube. Usually designed to provide light approximating to daylight. It is often regarded as artificial light source in the dark. Electronic flash requires a high voltage, usually obtained from batteries through a voltage-multiplying circuit. It discharges a brief, intense burst of light, usually used where the lighting on the scene is inadequate for picture-taking. They are generally considered to have the same photographic effect as daylight. Most flash will correct the color temperature back to 5000 Kelvin - the daylight color. You can play around with filters mounting on the flash head for some specific effects or alter the color if necessary. Modern flash has multiple TTL flash exposure control functions and even extend to autofocus control. Some specialized flash are high speed repeating flash which can use for stroboscopic effect, UV-flash for ultra violet light photography etc.

Electronic media
Any of the media used to publish information electronically (as opposed to print). Some examples are: presentation packages, annotated image catalogues, World Wide Web pages.

Electronic publishing
Composition of text (and frequently graphic images) using a computer for display in a computer presentation program or on the World Wide Web.

Electronic retouching
Enhancing a computer images with editing software.

Single lens used in association with others to form a compound construction.

Elliptical dot
A type of halftone screen dot with an elliptical rather than circular shape, which sometimes produces better tonal gradations.

Embedded profile
An ICC profile stored inside a TIFF, EPS, PDF, PSD, image, defining the colour space in which the image data are interpreted.

Applying a special effect to an image that gives it a 3-D, embossed-looking surface.

Emulsion Side
The side of the film coated with emulsion. In contact printing and enlarging, the emulsion side of the film-dull side-should face the emulsion side of the photo paper-shiny side.

Micro-thin layers of gelatin on film in which light-sensitive ingredients are suspended; triggered by light to create a chemical reaction resulting in a photographic image. Basically, suspension of light-sensitive silver salts in gelatine. The light-sensitive layer of film or paper. In black and white films the emulsion usually consists of very fine grain of silver halide suspended in gelatin, Which blacken when exposed to light. The emulsion of colour films contains molecules of dye in addition to the silver halide.

A technique used in preventing unauthorized third parties from viewing information that you are uploading or downloading. Encryption is most commonly used when credit card information is being transmitted. When encryption is used, the data being sent is split into sections and each section is sent through different connections. The two most common encryption patterns are 56-bit and 128-bit (the higher the number, the more secure the connection is).

Enhanced Back-Printing
An Advanced Photo System feature available in some system cameras that enables users to encode detailed information at the time of picture-taking, such as the date and time of exposure, camera settings, roll title or other custom information for subsequent printing onto the back of their photographs.

The improvement of an image either through colour and/or density change.

A print that is larger than the negative or slide; An image, usually a print that is larger than the negative. Made by projecting an enlarged image of the negative onto sensitized paper.

Enlarger head
The part of an enlarger that contains the light source, the negative carrier and the lens. An enlarger head also houses a filter drawer or a built-in filtration system.

A device consisting of a light source, a negative holder, and a lens, and means of adjusting these to project an enlarged image from a negative onto a sheet of photographic paper. An optical instrument ordinarily used to project an image of a negative onto sensitized paper. More accurately called a projection printer because it can project an image that is either larger or smaller than the negative.

An image processing technique where the range of tones or colours in an image file are expanded in order to produce a more pleasing image.

The process of removing information from memory or storage. Part of a file or image may be erased.

This tool is used to change the current colour of pixels to the background colour.

Exposure Value. Developed in order to simplify numbers used in exposure calculations. Currently used to describe the range of exposure in which equipment can successfully operate. Exposure value. Method of quantifying scene brightness. Most of these value apply to metering cells, how high or low e.g. a metering that can handles from EV1-EV21 means a metering system that can measure brightness level from just above the light level of a candle light to a brightly sunlight scene on a beach. Camera metering can handle more weakly on a spot meter than, say, a center weighted average metering system. EV is commonly used in black & White photographic process. At ISO 100, the combination of a one-second shutter speed and an aperture of F1.4 is defined as EV1. The camera may be used only within the EV range of the exposure meter. For example, the exposure metering range s from EV0 to EV20 can be used on a camera, means the camera's meter can handle broader range of exposure latitude.

A type of 8mm tape drive and storage cartridge.

Exchangeable Image File: the file format used by most digital cameras. For example, when a typical camera is set to record a JPEG, it’s actually recording an EXIF file that uses JPEG compression to compress the photo data within the file.

Existing Light
Available light. Strictly speaking, existing light covers all natural lighting from moonlight to sunshine. For photographic purposes, existing light is the light that is already on the scene or project and includes room lamps, fluorescent lamps, spotlights, neon signs, candles, daylight through windows, outdoor scenes at twilight or in moonlight, and scenes artificially illuminated after dark.

Expansion board
A circuit board that fits into an expansions slot located on the motherboard . Some adapter boards come installed in the computer, and others may be purchased at a later time to upgrade or add abilities to the computer.

Expansion memory
A method for fooling the computer into using more than the maximum 640K of RAM most personal computers are designed to use.

Expansion slots
Female slots located on the motherboard into which the male pins of an expansion board fit.

Expiry date
The date stamp on most film boxes indicating the useful life of the material in terms of maintaining its published speed and contrast.

The process of transporting data from one computer, type of file format, or device to another.

Exposure bracketing
Shooting the same subject at a range of different exposures. Some camera provides Auto Exposure Bracketing/Flash Exposure Bracketing.

Exposure compensation
Exposure compensation for available light is activated by changing the shutter speed and/or lens aperture. This is done by using AE L AF-L (Auto Exposure/Autofocus Lock) button or exposure compensation button, or by Auto Exposure Bracketing . In flash photography with a dedicated TTL Speedliqht exposure compensation can also be performed by varying the amount of flash output. Camera-originated exposure compensation affects both the foreground subject and the background; variations in flash output amount affect only the foreground. Many camera have the ability to force the camera to overexpose or underexpose an image during capture. This can be done for effect or to compensate for some particular lighting situation. This is often referred to as EV compensation.

Exposure factor
A figure by which the exposure indicated for an average subject and/or processing should be multiplied to allow for non-average conditions. Usually applied to filters. Occasionally to lighting. Processing, etc Not normally used with through-the-lens exposure meters.

Exposure index ( EI )
A film speed rating similar to an ISO rating abbreviated EI. When film is shot at something other than its rated speed setting, or ASA, The speed setting at which it is exposed is referred as the Exposure Index. For example, if Kodak Tmax 100 (TMX) Black and White film is exposed at 50, the exposure index for the film would be referred to as EI 50.

Exposure Latitude
The range of camera exposures from underexposure to overexposure that will produce acceptable pictures from a specific film. The range, in f-stop, that deviates from the optical exposure but will still produce acceptable results on a specific film.

Exposure Lock
There are times when the main subject of a frame is not in the center of the frame where metering is taken from. In order to properly expose the main subject meter on the subject, then hold the exposure lock option, then recompose the image to framing that is more suitable to the photographer. Often the exposure lock on modern cameras is to hold the shutter release button half way down after metering the scene, then recompose.

Exposure meter
An instrument for measuring the intensity of light so as to determine the shutter and aperture setting necessary to obtain correct exposure. Exposure meters may be built into the camera or be completely separate units. Separate meters can sometimes measure the light falling on the subject (incident reading) as well as the light reflected by it (reflected reading) ; built-in meters measure only reflected light. Both types of meters may be capable of measuring light from a particular part of the subject (spot metering) as well as taking an overall reading. Commonly called a light meter.

Exposure setting
The aperture and shutter speed combination used to expose the film in a camera.

Exposure value
Refers to the ability to override the auto exposure system on a digital camera to lighten or darken an image.

1. The act of letting light fall on a light sensitive material
2. The amount of light that passes through a lens (either a camera or photographic paper) to form an image. In the camera, too much light causes overexposure-this makes negative film look too dark and reversal film look too light. Underexposure (too little light) has the reverse effect. In enlarging, overexposure makes a print from a negative too dark and a print from a slide too light. Underexposure has the reverse effect. The quantity of light allowed to act on a photographic material; a product of the intensity (controlled by the lens opening) and the duration (controlled by the shutter speed or enlarging time) of light striking the film or paper. The act of allowing light to reach the light-sensitive emulsion of the photographic material. Also refers to the amount (duration and intensity) of light which reaches the film.

Extension bellows
Device used to provide the additional separation between lens and film required for close-up photography. Consists of extendible bellows and mounting plates at front and rear to fit the lens and camera body respectively.

Extension bellows
Device used to provide the additional separation between lens and film required for close-up photography.

Extension tubes
Metal tubes used to obtain the additional separation between lens and film for close-up photography. They are fitted with screw thread or bayonet mounts to suit various lens mounts. One of the necessary steps for Macro Photography is to move the lens away from the focal plane to allow closer focusing. Extension tubes are used for this purpose. They are similar to bellows except they are not flexible and distance is often not adjustable. Tubes made from metal and, more frequently, plastic inserted between the lens and the camera, thereby making the lens to film distance greater. The result is increased magnification for close-up photography.

External flash
A supplementary flash unit that connects to the camera with a cable, or is triggered by the light from the camera’s internal flash. Many fun and creative effects can be created with external flash.

External modem
A modem that resides outside the computer, and that attaches to the computer's serial port by cable.

Eye light
A highlight in the eye or the small light placed near the camera to produce it.

This tool takes a sample of a colour from an image so that it can be used as the new background or foreground colour.

Eyepiece shutter
A built-in device that prevents light from entering the viewfinder eyepiece.