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When a lens is focused on a subject, a certain distance in front of
and behind the subject will also be in clear focus. That distance
is called the "depth of field." The depth of field varies, depending
on certain conditions (see below). By using the depth of field
phenomenon, you can bring the subject into clear focus while
leaving foreground and background out of focus, or you can
create pictures in which both subject and background are in
clear focus. Consult the appended chart for more information.
A lens's depth of focus generally varies as follows:
Depth of field increases with smaller apertures,
and lessens with wider apertures.
Depth of field increases with increasing camera-subject
distances, and lessens with shorter distances.
Depth of field is greater behind the point of focus,
and shallower in front of the point of focus.
Also, lenses with shorter focal length (wide angle lenses)
tend to have inherently greater depth of field than lenses
with long focal length (telephoto lenses).
DEPTH OF FIELD
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