Nikon D40 - Manual (Page 54)

42 Reference: P, S, A, and M Modes/Mode A (Aperture-Priority Auto)
Mode A (Aperture-Priority Auto)
In aperture-priority auto, you choose the aperture from values between the minimum and
maximum for the lens while the camera automatically selects the shutter speed that will
produce the optimal exposure. Small apertures (high f/-numbers) increase depth of field,
bringing both the main subject and background into focus. Large apertures (low f/-num-
bers) soften background details.
To take photographs in aperture-priority auto:
1 Rotate the mode dial to A.
2 Rotate the command dial until the desired aperture is dis-
played in the viewfinder (aperture can also be displayed in the
monitor by pressing the
button).
3 Frame a photograph, focus, and shoot.