Canon EOS-1DX MARK II Settings Manual page 127

There are many useful settings that can be assigned to
each button with customization function C.Fn5 [Custom
Controls]. For example, when using AF functions that
can be assigned to the
of the camera, you can instantly switch functions to
match the subject and situation without changing how
you hold the camera.
When [AF/Metering start] is assigned to the
buttons, you can perform detailed settings in [AF start
point], [AI Servo AF characteristics (Case)], [AF
operation], and [AF area selection mode].
Using those settings, you can instantly switch
p a r a m e t e r s t o m a t c h s u b j e c t m o v e m e n t a n d
characteristics by using the
Case1, and the
the button to switch to AI Servo AF, and the
button to switch to One Shot.
[ONE SHOT
and buttons. You can customize controls to meet
your preferences or the scene.
and
button to switch to Case2, or using
AI SERVO] can also be assigned to the
127
buttons on the back
button to switch to
or