Canon FD Lens Manual Book page 15

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• Depth of field is narrow at wide apertures,
greater when the lens is stopped down.
The four pictures at left were taken with the
same lens from the same distance, but at dif-
ferent apertures. As you can see, the more the
lens is opened, the narrower the depth of field
becomes; the more the lens is closed, the great-
er the depth of field. By using a large aperture
such as f/1.4, you can make the background and
foreground appear blurred, and by stopping the
lens down as much as possible (to f/16 or so), the
entire picture will be sharp. Blurred backgrounds
call attention to the main subject and de-
emphasize unneccessary details; sharp back-
grounds tend to portray the subject in its over-
all surroundings. In other words, the aperture
should be varied to suit the mood and nature of
your subject.
• Depth of field is greater with wide angles,
smaller with telephotos.
The pictures to the right were taken from the
same distance, but with 28mm, 50mm, and
135mm lenses. An aperture of f/4 was used in all
cases. By comparing the enlargement of the
50mm shot with the 135mm shot, you can see
that depth of field is greater with the 50mm than
it is with the 135mm telephoto lens. Depth of
field is greatest with the 28mm lens. Thus, given
the same aperture, depth of field is deeper with
wide-angle lenses than it is with telephotos.
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