Canon EOS 20D Instruction Manual

3 Custom Function SettingsN

142

C.Fn-04

Shutter button/AE lock button

0: AF/AE lock
1: AE lock/AF

Convenient when you want to focus and meter separately. Press the <

button to autofocus and press the shutter button halfway to attain AE lock.

2: AF/AF lock, no AE lock

In the AI Servo AF mode, you can press the <

A> button to stop

the AF operation momentarily. This prevents the AF from being
thrown off by any obstacle passing between the camera and
subject. The exposure is set at the moment the picture is taken.

3: AE/AF, no AE lock

This is useful for subjects which keep moving and stopping
repeatedly. In the AI Servo AF mode, you can press the <

A> button

to start or stop the AI Servo AF operation. The exposure is set at the
moment the picture is taken. Thus, the focusing and exposure will
always be at the optimum point as you wait for the decisive moment.

C.Fn-05

AF-assist beam

You can set the AF-assist beam to be emitted from the camera or EOS-dedicated Speedlite.

0: Emits
1: Does not emit

AF-assist beam not emitted.

2: Only ext. ﬂash emits

When an EOS-dedicated Speedlite is used, the AF-assist beam is emitted only
when necessary. When the built-in ﬂash is used, the AF-assist beam is not emitted.

C.Fn-06

Exposure level increments

0: 1/3-stop
1: 1/2-stop

Sets 1/2-stop increments for the shutter speed, aperture, exposure
compensation, AEB, etc.

C.Fn-04 and C.Fn-17-0, 1, 2 (p.146) both have AF start/stop and AE lock
functions. If you have set both these Custom Functions and you execute
both Custom Function operations, the latter operation will not work. The only
exception will be when AF stop is executed after AF start.