Nikon D40 - Manual (Page 51)

Reference: P, S, A, and M Modes 39
P, S, A, and M Modes
P , S, A, and M modes offer control over a variety of advanced settings, including exposure (
45), white balance, and image optimization. Each of these modes offers a different degree
of control over shutter speed and aperture:
Mode Description
P
Programmed auto
( 40)
Camera sets shutter speed and aperture for optimal exposure. Recom-
mended for snapshots and in other situations in which there is little time to
adjust camera settings.
S
Shutter-priority
auto ( 41) User chooses shutter speed; camera selects aperture for best results. Use to
freeze or blur motion.
A
Aperture-priority
auto ( 42) User chooses aperture; camera selects shutter speed for best results. Use to
blur background or bring both foreground and background into focus.
M Manual ( 43)
User controls both shutter speed and aperture. Set shutter speed to “bulb”
or “--” for long time-exposures.
Lens Aperture Ring
When using a CPU lens equipped with an aperture ring , lock the aperture ring at the minimum aperture
(highest f/-number). Type G lenses are not equipped with an aperture ring.
Non-CPU lenses can only be used in exposure mode M , when aperture can be adjusted manually using
the lens aperture ring (in other modes, the shutter-release will be disabled). The camera exposure
meter and a variety of other features can not be used ( 97).
10—ISO Auto ( 76)
Use this option to enable auto ISO sensitivity control in P, S, A, and M modes.
Exposure
The same exposure can be achieved with different combinations of shutter speed and aperture,
allowing you to freeze or blur motion and control depth of field. The following figure shows how
shutter speed and aperture affect exposure.
Shutter speed Aperture
Fast shutter speed Small aperture (large f-/number)
Slow shutter speed Large aperture (small f/-number)