Leica M3 - The Depth-of-Field Scale

The Depth-ol-Field Scale
The lens reproduces sharpest those parts of the scene which are at the exact distance
- in a plane pa rallel to the film - on which it is focused. This maximum sharpness
gradually falls o ff in front of, and behind, the focused distance, resulting in a certain
zo ne w ithin w hich everything is still acceptably sharp . The extent of this zone of
s harpn e ss -. lhe " dep t h-of-field " - depend s on the subiect d is tance , the focal length of
the lens, and the aperture . Stopping down increases the sharp field, which is desirable
for mosT subiects extending appreciably in depth .
To
find the limits of this zone, look at the depth of field scale of your lens. The sharp
zone is that enclosed between two index lines of the same aperture number . If , for
instance, you have set your 50 mm
SUMMICRON lens to 15 feet , the
avai lable dep th- of-f ield with an
aperture of f/4 (see red arrows in
the
illustration ) extends from about
12 V2 to 20 feet. If , however , you
stop down to f il l , the zone of
sharpness cove
rs a field from a bout
9 to 40 feei ·. When altering the
aperture, be sure to adiusl' the ex-
po sure time according .ly.
Soc also page 9, O;>li cal D ept h· ol· fi eld
In:licaror in th:J measuring fie ld or the (on"'l·
bined range-viewfinder.
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