Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 346)

(Face)+Tracking:
The camera detects and focuses on people's faces. If a face moves, the AF point < >
also moves to track the face.
You can set [
: Eye Detection AF ] to [ Enable ] to shoot with the subject's eyes in focus
( ).
1.
Check the AF point.
An AF point < > appears over any face detected.
To choose a face to focus on when multiple faces can be detected,
press the <
> button to change the AF point to < >, then use
< >. As you use < >, the AF point changes again to < >.
You can also tap the screen to choose a face.
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