Canon EOS-1D X Mark III Af Setting Manualbook page 44

AF point expansion
Focus using one manually selected point assisted by
4 other AF points (up, down, left, and right) or
surrounding points.
Viewfinder shooting
[AF point expansion
(manual selection
Viewfinder shooting
[AF point expansion
(manual selection: surround)]
Zone AF
When using the optical viewfinder AF points are
divided into nine zones, with the focus point used
being within the selected zone. During Live View
shooting, the focus point is any within the selected
zone.
Viewfinder shooting
[Zone AF
(Manual selection of zone)]
Live View shooting
[AF point expansion ( ） ]
） ]
Live View shooting
[AF point expansion (Around)]
Live View shooting
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[Zone AF]