Controls In Detail - Nikon F3 Instruction Manual

-CONTROLS IN DETAIL-continued----------
The F3 has two separate settings for time exposures . On
"B," the shutter remains open for as long as the shutter
release button is depressed. On "T," the shutter stays
open until the dial is rotated to another setting, making it
ideal for really long time exposures. Being a mechanical
setting, "T" will not cause battery drain regardless of how
long the shutter remains open.
"X" provides a shutter speed setting of 1/80
sec. It is used
18
to provide proper synchronization with electronic flash
units other than the Nikon SB-12.
The amount of light reaching the film plane is determined
by a combination of the shutter speed and the lens
aperture. Since the two are interrelated, different combi-
nations will give the same degree of exposure. A one-step
change in shutter speed, or .a one-stop change in aper-
ture setting, will either halve or double the degree of ex-
posure. For example, a shutter speed of 11125 sec. lets
in twice as much light as a setting of 1/250 sec., and only
half as much light at 1/60 sec. For an aperture setting of
fill , twice as much light as flI6 and half at much as fl8,
is let in. Thus, if the correct exposure for a particular
picture-taking situation is 1/125 at
fill,
then 1/60 at
fl16
or 1/250 at
fl8
will give the same exposure. The following
table illustrates the interrelation between shutter speed
and aperture .
The best combination will depend on the results you
want. Use fast shutter speeds to freeze motion; use slow
speeds to produce a deliberate blur. (See the example
pictures on the opposite page.). Also, small apertures
give greater depth of field, while large apertures restrict
sharp focus to the main subject. (See page 26.)
A good rule to follow in preventing camera shake is to
select a minimum shutter speed which is the reciprocal of
the focal length of the lens in use. For example, when
using a normal 50mm lens, select a speed no slower than
1/60 sec. (the closest number to 1/50). For a 500mm
super-telephoto, use no less than 1/500 sec., and so forth.