Nikon Camera N90 - Manual (Page 78)

Shutter-Priority Auto exposure mode
You manually set the shutter speed you want. To freeze the
action, use a high shutter speed; to create motion effects,
choose a siower shutter speed. The N90's microcomputer
automatically sets the proper aperture to match the manually
selected shutter speed for correct exposure. See pp. 56-59 for
Shutter-Priority Auto operation.
Note that Shutter-Priority Auto exposure mode operates only
with Nikon lenses that have a built-in CPU (AFNikkor and Al-P
Nikkor lenses).
Aperture-Priority Auto exposure mode
You can control depth of field by varying the aperture. Smaller
apertures make the background and foreground sharper
(recommended for landscape pictures) while larger apertures
tend to blur the background (recommended for portraits).
Your selected aperture will determine the shutter speed that is
automatically set by the camera’s microcomputer. When using
smaller apertures with correspondingly slower shutter speeds,
remember that, generally, any speed below 1/(focal length in
use) second, requires the use of a tripod to prevent picture blur
due to camera shake. The higher the corresponding shutter
speed to the aperture you set, the easier it is to stop action.
Adjust the selected aperture if the speed is not appropriate for
conditions or the specific effect you want.
For Aperture-Priority Auto operation, see pp. 60-62.
52