Nikon Camera F3AF - Manual (Page 55)

3) The longer the focal length of a lens, the shallower the depth
of field at each f/stop; the shorter the focal length, the deeper
the depth of field.
4) There is greater depth of field behind the main subject than
in front of it.
The depth of field at each aperture is indicated on the lens by a
set of color-coded lines ® (corresponding to the colors of the
f-numbers on the aperture ring) which are used in conjunction
with the distance scale ®. The range is indicated by the dis­
tance between the lines.
Note: Certain Zoom-Nikkor and special-purpose Nikkor lenses do not
have a depth-of-field scale.