Nikon D330018-55VR User Manual (en)

106 P, S, A, and M Modes
Mode A (Aperture-Priority Auto)
In this mode, you can adjust aperture to control depth of field 
(the distance in front of and behind the main subject that 
appears to be in focus). The camera automatically adjusts 
shutter speed for optimal exposure.
To choose an aperture:
Rotate the mode dial to A.
Large apertures (low f-numbers, e.g. 
f/5.6) blur details in front of and 
behind the main subject.
Small apertures (high f-numbers, e.g. 
f/22) bring the foreground and 
background into focus.
Mode dial