Canon EOS-1 D X Mark II Instruction Manual page 132

3 Customizing AF Functions
AF area selection method
You can set the method for changing the AF area selection mode.
When [S 9 Main Dial] is set, use the <9> to move the AF point
horizontally.
Orientation linked AF point
You can set the AF point or the AF area selection mode + AF point
separately for vertical shooting and horizontal shooting.
132
9 M-Fn button
After you press the <S> button,
pressing the <B> button changes
the AF area selection mode.
9 Main Dial
After you press the <S> button,
turning the <6> dial changes the
AF area selection mode.
: Same for both vert/horiz
The same AF area selection mode
and manually-selected AF point (or
zone) are used for both vertical
shooting and horizontal shooting.