Canon EOS 40D - Manual (Page 160)

160
3 Custom Function SettingsN
C.Fn III -6 AF during Live View shooting
0: Disable
1: Enable
During Live View shooting, you can interrupt the Live View image
display and focus for as long as you hold down the
button.
C.Fn III -7 Mirror lockup
Prevents camera vibrations caused by the reflex mirror action which can
disturb shooting with super telephoto lenses or close-up shooting. See
page 98 for the mirror lockup procedure.
0: Disable
1: Enable
C.Fn IV: Operation/Others
C.Fn IV -1 Shutter button/AF-ON button
0: Metering + AF start
1: Metering + AF start/AF stop
During autofocusing, you can press the
button to stop the
autofocusing.
2: Metering start/Metering + AF start
This is useful for subjects which keep moving and stopping repeatedly.
In the AI Servo AF mode, you can press the
button to
repeatedly start or stop the AI Servo AF operation. The exposure is set
at the moment the picture is taken. Thus, the optimum focusing and
exposure will always be achieved as you wait for the decisive moment.
3: AE lock/Metering + AF start
Convenient when you want to focus and meter at different parts of the
picture. Press the
button to meter and autofocus, and press
the shutter button halfway to attain AE lock.
4: Metering + AF start / disable
The
button will not function.