Canon AE-1 - Manual (Page 49)

"A'' marte.
This is because the aperture value 1 %
stored in the AE circuit as a result ot itopp*
ir>g-dowrt the lens, ar>d you will end up getting
incorrect automatic exposure (or the next
shot«
\ f you fail to do that.
Generally« the depth-o(’field will become
deeper as the aperture becomes smaller« and
shallower as the aperture becomes larger. A
shorter focal length
at well as a greater subject
distance will also deeper^ the depth-of field.
Compering an interchangeable 28mm lens
with a standard SOmm lens set at the same
f/stop« the 28mm lens's depilvof-field will be
greater. And when the photographic distance
char^ges« the depth-of-field changes« too. For
example, if the same sublect is photographed
from three and then from seven meters away,
the foreground and background of the subject
will be deeper et the greater distance.
2 Depth*of*Field Scale on the Lens
A depth-of-field scale is engraved on the
lens barrel, shown as a series of f/rmmbers on
each side of the distance irsdex mark opposite
the distance scale. Focusing and depth-of*field
are so closely interrelated that the depth-
of-field scale is engraved together with the
distance scale.
You can tell the extent of depthof-fleld
from the distence scale. For example, if vou
use the camera with a standard SOmm lens
that is focused on a subject at medium dis*
tarsce« say 3m with the aperture set at f/8«
the depth'Of'field extends from 2.4m to 4.5m.
This tells you that with the SOmm lens
focused at 3m and the subject between 2.4m
and 4.5m the film image will be reasonably
sharp.
44