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Depth-of-Field Scale
The depth ·of·field
scale
indicates the range of subjects
which will be in
sharp
focus on the film.
In this
case,
the
depth ·of ·field behind the
subject is
deeper than
in
front
of
subject.
This range will vary with the following factors
:
The depth ·of ·field will be deeper, the larger the f/stop num
·
ber, the further the distance of the
subject
,
and/or the
shorter the focal length of the lens
.
The depth ·of ·field will
be shallower, the
smaller
the f/stop number
,
the
nearer
the
distance of the subject, and/or the longer the focal length
of the lens.
For example
,
if the
lens
is 50mm and the
subject has
been
focused at a distance of 3m (10
'
),
with an
f
/
8 aperture
opening read off from both inde
xes on either side of
the
in·
dicator (orange line),
the
appro ximate depth
·of
·field
is
from
2 .3m
(8'
) to 4.3m
U4'
).
If the aperture
is
closed down
to
f
/ 16,
the picture
will
be
·
come sharp when the subject is between 1.9m (6
'
) to 7.6m
(25'
) from the
camera
.
This
range
will
vary
with the
select·
ed f/stop
.
•
In the
case
of Canon FD
lenses
,
you
can
see the actual
sharpness through the viewfinder by pressing the
stopped·
down functioning lever
.
•
Although air bubbles may sometimes be seen in a
lens,
they do not affect the resolution power or the sharpness of
the picture
.
38
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