DEPTH-OF-FIELD
When the lens is focused on a subject at some distance, not
only the subject but also a certain area around the subject
will be sharply delineated in a photograph, and this area is
known as a Depth-of-Field and has the following features.
a. The bigger the f-number, the larger the Depth-of-Field.
b. The farer the distance at which the tens is focused, the
bigger the Depth-of-Field is.
c. When the lens is focused on a subject, the Depth-of-Field
is bigger for the section in front of the subject than the
area behind the subject.
d. The shorter the focal length, the bigger the Depth-of-
Field.
The depth-of-field may be ascertained either with the depth-
of-field scale or with the manual aperture. As for details,
reference is made to the table of depth-of-field.
Using Table of Depth-of-Field: The Depth-of-Field Scale (6)
is so calibrated that readings identical to those of the lens
aperture are provided on both sides of the Distance Scale
Index Mark (7). For example, let us assume that the
distance between the film plane and the subject on which a
50mm f/1.7 lens has been focused is 15 feet. The Depth of
Field will be 12 to 19 feet for f/4 and 8 feet to °°(infinity)
f o r f/16.
INFRARED FILM COMPENSATION MARK:The point of
focus is somewhat different in infrared photography as
compared to normal photography. After the lens has been
focused as in normal photography, read the calibration on
the Distance Scale (8) aligned with the Distance Scale Index
Mark (7) and bring this reading in line with the Infrared
Film Compensation Mark (59) before the shutter is released
for a shot.
42
Depth-of-Field for f/16
(7) Distance/Aperture
Scale Index Mark
(6) Depth-of-Field Scale
Atf/2
for f/4
(8) Distance Scale
(59) Infrared Film
Compensation Mark
Atf/16