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Photography Terms

A B C D E F G H L N I P R S T U W Z

A

angle of view - widest angle at which light rays are accepted by a lens for a usable image on the film. Understanding Focal Length

aperture - a. adjustable opening in a camera that limits the amount of light passing through a lens. b. The diameter of such an opening, often expressed as an f number. The Aperture, Understanding Exposure

aperture priority camera - semiautomatic camera on which the photographer sets the aperture and the camera automatically sets the shutter speed. Understanding Exposure

ASA - a. American Standards Association. b. the sensitivity (speed with which it reacts to light) of a film. Film Speed

B

blur - un-sharp image areas, created or caused by camera or subject movement or by improper focus. Understanding Focus

bulb - setting for holding the shutter open for any time interval.

C

camera - see single lens reflex.

camera obscura - the origin of the present day camera, in its simplest form consists of a dark box and a small hole on one side.

D

depth of field - distance covered by acceptable sharpness of an image, extending in front of and behind the point of focus. Depth of field

diaphragm - see aperture.

E

electronic flash - a unit which produces a very bright flash of light, which lasts only for a short time. The electronic flash is caused by a high voltage discharge between two electrodes enclosed in a glass cylindrical bulb containing an inert gas such as argon or krypton. Flashes

exposure - the product of intensity of light and the time the light is allowed to act on the film. Understanding Exposure

F

f number - size of aperture. see aperture The Aperture

film - photographic material consisting of a thin transparent plastic base coated with light sensitive emulsions. Film Speed

film speed - see ASA. Film Speed

filter - any material which, when placed in front of a light source of lens, absorbs some of the light coming through it to modify the light reaching the film. Using Filters

flash - see electronic flash. Flashes

focal length - distance between the optical center of a lens focused at infinity and the film plane. Understanding Focal Length

focal plane shutter - a shutter that is positioned just in front of the film (Focal Plane). The exposure results from a slit traveling at a constant speed across the film - the actual shutter speed depending on the width of the slit. How the Shutter Works

focusing - the act of adjusting the lens-to-film distance so that the subject is sharply focused. Understanding Focus

G

grain - the random pattern within the photographic emulsion that is made up of the final (Processed) metallic silver image. The grain pattern depends on the film emulsion, plus the type and degree of development. Film Speed

H

halving and doubling - the reciprocal relationship between shutter speed and aperture with a given film speed. Understanding Exposure

hot shoe - metal slot, usually on the top of a camera, for holding a flash and flash synchronization. Flashes

I

infinity - in theory, this is a point that can never be reached, a measureless distance from the lens, in practice, a subject is said to be at infinity when going farther away makes no difference to the focusing of the lens. Understanding Focus

ISO - International Standardization Organization. see ASA. Film Speed

L

lens - optical element made of glass or plastic, capable of bending light. Protecting your Lenses

N

negative - the image produced by on a photographic emulsion by the product of exposure and development.

P

point of focus - distance from camera where image is its sharpest. Understanding Focus

polarizing filter - filter can be used to reduce reflections from surfaces such as water and glass, and also to darken the sky in color photographs. Using Filters

preflash - flash that fires one or more preliminary pupil-narrowing flashes then takes the photo to reduce redeye. Redeye Reduction

R

redeye - occurs when a flash positioned near the lens of the camera enters the pupils of a subject's eyes, then bouncing off the blood-rich retinal membranes back to the camera. Redeye Reduction

S

shutter - device which controls the duration of the exposure. How the Shutter Works

shutter priority camera - semiautomatic camera on which the photographer sets the shutter speed and the camera automatically sets an appropriate aperture. Understanding Exposure

shutter speed - determines the amount of time the film is exposed to light. Shutter Speed

single lens reflex (SLR) - a camera which views the subject through the lens via a mirror.

standard lens - camera lens with a focal length approximately equal to the angle of view similar to the human eye (50mm). Understanding Focal Length

T

telephoto lens - lens with a longer than standard (50mm) focal length. Understanding Focal Length

TTL - "through the lens", referring to a metering system where it meters through the lens which takes the photograph.

U

U/V filter - blocks ultraviolet rays as well as dust and liquid from reaching the lens.

W

wide-angle lens - lens with a greater field of view and a shorter focal length than a standard lens (50mm). Understanding Focal Length

Z

zoom lens - lens of a variable focal length. Understanding Focal Length

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