Canon EOS Rebel XT - Manual (Page 149)

149
3 Custom Function SettingsN
C.Fn-4 Shutter button/AE lock button
0: AF/AE lock
1: AE lock/AF
Convenient when you want to focus and meter separately. Press the <
A>
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 optimum
focusing and exposure will always be attained as you wait for the decisive moment.
C.Fn-5 AF-assist beam
You can enable or disable the camera’s AF-assist beam or have it
emitted by the EOS-dedicated Speedlite instead.
0: Emits
1: Does not emit
The AF-assist beam is not emitted at all regardless of the shooting conditions .
2: Only emits ext. flash
With an EOS-dedicated Speedlite, it will emit the AF-assist beam
when necessary. The camera’s built-in flash will not emit the AF-
assist beam regardless of the shooting conditions.
C.Fn-6 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.
The exposure level will be displayed in the viewfinder and on the LCD panel as shown below.