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DEPTH OF FIELD
Depth
of field
refers
to a zone within
which blur (or lack
of
definition) will be negligible
and everything
can be
accepted as
being
in
sharp focus.
Depth
of field extends a greater
distance
behind
the subject
in
focus than
in
front.
It depends
on two
factors-
reproduction
ratio
and aperture.
The
smaller
the
aperture and
the
greater
the reproduction
ratio, the
greater
the
depth
of field.
By
carefully considering
the desired pers-
pective
and
reproduction
ratio, as
well
as available f-stops, full
control of the
depth
of field
is
achievable.
Depth-of-field scale
The depth of
field can
be read
from
the color-coded scale
engraved on the
lens. The pairs
of colored
lines
correspond to
f/numbers
of
the
same
color. To
find
the depth
of field at a
particular
aperture, first focus on
the subject. Then check
the
numbers
on the
distance
scale opposite
the
colored
lines
which
correspond
to
the color of aperture
10
find the
depth
of field at
that
aperture.
For
example,
f/16
on
the aperture
ring of the
50
mm
f/l.4
lens is
blue.
With
the
lens prefocused
at
17 feet
(5
m) the numbers on
the
distance
scale
opposite
the
blue lines
show that
the depth of field
extends
from
9
feet
to
infinity
(00).
Remember that
smaller
apertures, although rendering a greater
depth
of field,"
require
slower shutter
speeds. Consider both
factors
carefully
before
shooting,
and always focus accurately.
Lens
at f/2 small
depth
of
field
Lens
at f/11
larger depth of
field
47
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