Canon EOS-1DS Mark III Instruction Manual page 168

Custom Function Settings
0: AF stop
1: AF start
AF operates only wMle the button is pressed. WMte the button is
pressed, AF operation with the camera is disabled.
2: AE lock
When the button is pressed, AE lock is apptied. Convenient when you
want to focus and meter at different parts of the picture_
3: AF point: M _ Auto/Auto -_ ctr
in the manual AF point selection mode, the button instantly switches to
automatic AF point selection (among 45 AF points) while you hold it
down. Convenient when you are no longer able to focus track a moving
subject wkh a manually-selected AF point in the AI Servo AF mode. You
can instantly switch from manual to automatic AF point selection mode.
in the automatic AF point selection mode, the button selects the center
AF point only while you hold it down.
4: ONE SHOT .,_ AI SERVO
in the One-Shot AF mode, the camera switches to A_ Servo AF mode
only wMle you hold down the button. And in the AI Servo AF mode, the
camera switches to One-Shot AF mode only while you hold down the
button.
Convenient when you need to keep switching between One-Shot AF
and AI Servo AF for a subject which keeps moving and stopping_
5: IS start
With the lens' IS switch already <ON>, the Image Stabilizer operates
when you press the button.
6: Switch to registered AF point
While holding down the AF Stop button, press the
<FEL>
button to
switch to the registered AF point. Press it again to switch to the previous
AF point.
®The AF stop button iS provided Only on Super telephoto Is ienSesl
® With setting 5, the Image Stabilizer wilI not operate when you press the
shutter button halfway.
To register the AE point, see page 17_.
168