Canon EOS-1DX Af Setting Manualbook page 118

In firmware V2.0, new settings can be assigned using
customization function C.Fn5 [Button Customization].
When using AF functions that can be assigned to the
and buttons on the back 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 mode],
and [Super high-speed continuous shooting mode].
Using those settings, you can instantly switch parameters
to match subject movement and characteristics by using
the button to switch to Case1, and the
to switch to Case2, or using the
to AI Servo AF, and the
Because [ONE SHOT
to the and
to meet your preferences or the scene.
button to switch to One Shot.
AI SERVO] can now be assigned
buttons, you can customize controls
118
or
button
button to switch