Canon EOS 5D Mark III Instruction Manual page 330

82: Custom Controls
: Metering and AF start
When you press the button assigned to this function, metering and AF
are executed.
*1: If you assign the [Metering and AF start] function to the <p> and <A>
buttons and add the function to switch to the registered AF point, you can instantly
switch to the registered AF point. To enable this function, press the <B> button in
step 3 on page 327. On the [AF start point] selection screen, select [Registered AF
point].
Registering and using an AF point
1. Set the AF area selection mode to one of the following: Single-point
Spot AF, Single-point AF, AF point expansion (manual selection,
surrounding points), or 61-point automatic selection AF. (Zone AF
cannot be registered.)
2. Select an AF point manually (p.74).
3. Hold down the <S> button and press the <U> button. A beep will
sound and the AF point will be registered. If the AF area selection
mode is not set to 61-point automatic selection AF, the registered AF
point will blink.
If [24: Orientation linked AF point] is set to [Select separate AF
points], you can register the AF point separately for the vertical
(camera grip at top or bottom) and horizontal orientations.
4. When you press the <p> button assigned to this function or
press the <A> button, the camera will switch to the manually-
selected AF point when you registered.
To cancel the registered AF point, hold down the <S> button and
press the <m> button. The registered AF point will also be
canceled if you select [54: Clear all camera settings].
When an AF point is registered, the following will be displayed:
• 61-point automatic selection AF:
• Single-point Spot AF, Single-point AF, AF point expansion: SEL
(Center)/SEL HP (Off-center)
When registered with SEL
330
HP
or SEL HP, the registered AF point will blink.