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<Exposure>
Exposure is the act of exposing the film to light, thus converting brightness val-
ues in a scene to tonal values on film. Exposure is composed of the size of the
opening in the lens (the aperture) and the duration of time in which the light
passes through the lens to strike the film (the shutter speed.)
<Shutter speed>
The camera adjusts the amount of light to which the film is exposed by adjusting
the length of time in which the shutter is open. The length of time that the shut-
ter is open is called the shutter speed.
<Aperture value>
The aperture is an opening in the lens. The amount of light passing through the
aperture to the film is adjusted by increasing or decreasing the diameter of the
opening. The size of this opening is called the aperture value.
<Film speed or sensitivity (ISO value)>
The film speed indicates the extent to which the film reacts to light, and is
expressed as a figure determined by the ISO (International Standardization
Organization).
REFERENCE
1. Basic information on photography
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