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E

ED:
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. Pentax and Olympus use the same name as Nikon. Canon's version is called "L" - with red lining and usually their lenses are white in colour. 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. Also please refer to "apodchhromatic" .

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.

EIS:
Electronic Image Stabiliser, better known and often termed as IS. A feature that minimises effect of camera shake. Originally designed for video cameras, Canon has transferred the technology over to its EF lenses and it can offer the facility to hand hold and capture sharp images at slow shutter speeds.

Electronic flash:
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 colour temperature back to 5000 kelvin - the daylight colour. You can play around with filters mounting on the flash head for some specific effects or alter the colour 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 strobocopic effect, UV-flash for ultra violet light photography etc.

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

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. On modern digital cameras is now embedded into the image and if referred to as EXIF data. Many software packages and utilities can read and extract this information.

Enlargement:
A print that is larger than the original image; also see "blowup".

EV:
Exposure value. Method of quantifying scene brightness. Most of these values apply to metering cells, how high or low e.g. a metering that can handle 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 centre 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 ranges from EV0 to EV20 can be used on a camera; means the camera's meter can handle broader range of exposure latitude.

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.

Exposure:
The quantity of light allowed to act on a sensor or 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 sensor or film.

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 flashgun exposure compensation can also be performed by varying the amount of flash output.

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 Latitude:
The range of camera exposures from underexposure to overexposure that will produce acceptable pictures.

Exposure Meter:
An instrument with a light-sensitive cell that measures the light reflected from or falling on a subject, used as an aid for selecting the exposure setting. The same as a light meter.

Extension bellows:
Device used to provide the additional separation between lens and sensor 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 tubes:
Metal tubes used to obtain the additional separation between lens and sensor for close-up photography. They are fitted with screw thread or bayonet mounts to suit various lens mounts and can allow for very close focusing to a subject.