Contax G2 - Page 94

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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).