Nikon fe - Manual (Page 22)

DEPTH OF FIELD
When you focus on your subject, you will find that not
only is the subject itself in focus but that objects both in
front of and behind it appear to be in focus. This “zone”
of focus is called “depth of field.”
Depth of field is not a fixed quantity. It varies by lens,
depending on both the subject’s distance from the
camera and the specific lens aperture in use. A third
factor, the focal length of the lens, also influences the
apparent depth of field, i.e., the longer the lens, the
shallower the depth of field appears to be, and vice versa.
In the same manner, the wider the taking aperture (i.e.,
the lower the f/stop number), the shallower the depth of
field, and-vice versa. Also, the closer you approach your
subject, the shallower the depth of field becomes, and
vice versa. In all cases, you will find that the depth of
field behind the subject is larger than that in front.
Depth-of-Field Preview Lever
Most Nikkor lenses are “automatic.” This means that
the aperture diaphragm remains open at its widest while
you are viewing, focusing and metering. When you press
the shutter release button, the camera automatically
“stops down” the diaphragm to the aperture which is set
on the aperture ring.
To examine the depth of field before taking a picture, it
is necessary to stop down the lens manually. You can do
this by pushing the depth-of-field preview lever. Assum­
ing that the lens is not set to its maximum aperture,
depressing the lever will stop down the lens to that
aperture. You will then be able to see the elements in
front of and behind the main subject that will be in
sharp focus in the final photograph—although some of
them may have not appeared to be In focus prior to
pushing the lever. A side effect is the “darkening” of the
image in the viewfinder (the higher the f/number, the
darker the image appears); this is normal and should be
no cause for concern. Note that the correct “automatic”
exposure cannot be obtained if the lever is depressed
when the shutter is released. After jtaking a stopped-
down meter reading, you can release the shutter with the
depth-of-field lever depressed, but it must be depressed
all the way. Otherwise, the shutter may not open.
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