Checking The Depth Of Field - Canon A-1 Instructions Manual

make a rocu. s ing correction . Follow the
detailed instructions of the film manu-
facturer.
The position of the infrared index mark has
been computed for the use of infrared film
with peak sensitivity at 800nm (such as
Kodak
IR 135) and
a red filter .f'uch as
Wratt en 87.
-76-
Checking the Depth of Field
There are two ways to find out what th e
depth of field is. One is by using the depth
of field scale which is a series or f/stops
repeated on each side or the distance index
m;u-k on the lens b arrel. The scale differs
accor ding to the le ns. First focus your
subject. Find the two f/stops on the depth
of field scale which correspond to the
aperture you or the camera have set for the
exposure . Draw imagina1y lines from these
two f/ st.ops to t-he distance scale. The
effective dep th of field extends between
those two d istances. For example , using a
standard 5 0mm le ns focused at 3m with the
aperture set a t f/8, depth of field extends
from 2.4rn to 4.5m. Any subject from
2.4rn to 4.5rn away will be in reasonably
sharp focus in the image.
You can a lso visually check the depth of