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DE P THO F FIE L D. In addition to the exposure, the aperture
a
lso determines the
zone of sharpness in front of, and behind, the focused distance. Small apertures
(stopping down) appreciably
increase
this zone of sharpness, giving what is
called.
great depth of field. The depth of field also
increases-
the farther away the subject is
from the camera. The aperture and the distance focused on are therefore the two
factors governing the depth of field. The resulting zones of sharpness for the various
settings are given
in
the table on page 3S.
Contrary to the illustrations on the inner pages of this
instruction
booklet the new model
of Karat 36 has, instead of a depth of field ring, a depth of field indicator as shown
in
the figure below.
Two sets of aperture numbers
are
arranged symmetrically to the left and right of the
focusing mark. The corresponding divisions, pointing to the focusing scale, show the
limits of the zone of sharpness at any
setting.
In our illustration the focusing scale
is
set to
10
feet.
By following the lines corresponding to the
two figures 8, we thus see that the depth of
field at
aperture
8 extends from 6 to about
20 feet, or at aperture 11 from S to about
30
feet.
For the sake of clarity the
indicator
has
been calculated for a circle of confusion of
1/
500
inch
(O .OS
mm.).
The figures given are
therefore on the generous side, and for more
accurate work
the values of the Depth of Field
Table (page
3S)
should
be used.
18
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