Nikon D90 user manual Shutter Speed and Aperture, Lens Aperture Rings

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Shutter Speed and Aperture

P, S, A, and M modes offer different degrees of control over shutter speed and aperture:

	Mode	Description
	Programmed auto	Camera sets shutter speed and aperture for optimal exposure.
P		Recommended for snapshots and in other situations in which
	(pg. 80)	there is little time to adjust camera settings.
S	Shutter-priority auto	User chooses shutter speed; camera selects aperture for best
	(pg. 81)	results. Use to freeze or blur motion.
	Aperture-priority auto	User chooses aperture; camera selects shutter speed for best
A		results. Use to blur background or bring both foreground and
	(pg. 82)	background into focus.
M	Manual (pg. 83)	User controls both shutter speed and aperture. Set shutter speed
		to “A” or “&” for long time-exposures.

DLens Aperture Rings

When using a CPU lens equipped with an aperture ring (pg. 228), 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, auto ISO sensitivity control, and variety of other features can not be used (pg. 165).

ASee also

Use the ISO sensitivity auto control option in the shooting menu (pg. 165) to enable auto ISO sensitivity control in P, S, A, and M modes. Custom Setting b1 (EV steps for exposure cntrl.; pg. 177) determines the size of the increments used for setting shutter speed and aperture. Custom Setting f5 (Customize command dials; pg. 201) determines the roles played by the main and sub-command dials in setting shutter speed and aperture.