- CONTROLS IN DETAIL-continued
---------
Setting the aperture
The lens aperture determines the amount of light reaching the
film plane. Generally, when
you
turn the aperture ring one
graduation
in
the direction of the larger numbers, the amount
is
reduced by 1/2. (This
is
what stopping down
by
one graduation
means.)
On
the other hand, when the aperture ring
is
turned one
graduation
in
the direction of smaller numbers, the amount of
light
is
doubled. (This
is
known
as
opening the aperture
by
1
stop.) The lens aperture ring clicks at the position of the numbers
engraved although intermediate lens apertures are usable con-
tinuously. Lens aperture greatly affects depth of field (see page
28)
. With the exception of a few special lenses, Nikkor and
20
Nikon Series E lenses enable full-aperture light measurement
even when the aperture ring
is
moved. These lenses, which are
said to have
an
automatic diaphragm, stop down to the set
aperture only at the instant the shutter release button
is
depressed.
