Canon EOS 80D - Manual (Page 162)

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In this mode, you set the desired aperture and the camera sets the
shutter speed automatically to obtain the standard exposure matching
the subject brightness. This is called aperture-priority AE. A higher
f/number (smaller aperture hole) will make more of the foreground and
background fall within acceptable focus. On the other hand, a lower
f/number (larger aperture hole) will make less of the foreground and
background fall within acceptable focus.
* <f> stands for Aperture value (aperture opening).
1
Set the Mode Dial to <f>.
2
Set the desired aperture.
 While looking at the LCD panel, turn
the <6> dial.
3
Focus on the subject.
 Press the shutter button halfway.
X The shutter speed is set automatically.
4
Check the viewfinder display and
shoot.
 As long as the shutter speed is not
blinking, the standard exposure will
be obtained.
f
: Aperture-Priority AE
Sharp foreground and background
(With a high aperture f/number: f/32)
Blurred background
(With a low aperture f/number: f/5.6)