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<Aperture>
The aperture in the lens controls the amount of light going through
the lens by becoming smaller or larger. The size of the opening is
called aperture value. The larger the aperture value the smaller the
opening.
<Shutter speed>
By varying the amount of time it remains open, the camera's
shutter controls the amount of light reaching the film. The length of
time the shutter remains open is called the shutter speed.
<Exposure>
"Exposure" means to expose the film to light. The amount of light
allowed to strike the film is controlled by the combination of
aperture and shutter speed.
<Film speed> (ISO value)
The film speed refers to a given film's sensitivity to light, measured
according to numerical values established by the International
Standards Organization (ISO). The smaller the ISO value, the lower
the film's sensitivity to light.
The larger the ISO value, the higher the film's sensitivity to light (the
film is sensitive to lower levels of light).
<Depth-of-field>
In general, when the lens is focused on a given subject, not only
the subject itself, but a certain area in front of and behind the
subject will also be in focus.The range between the nearest and the
farthest point that is sharp is the "depth-of-field." The depth-of-
field on any given lens will change in the following way:
® As the aperture is closed, the depth-of-field becomes larger, and as the
aperture is opened, the depth-of-field becomes smaller.
(D The depth of field becomes larger as distance to the subject increases,
smaller at closer distances.
@ The depth of field is larger behind than in front of the subject in focus.
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