Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 352)

Setting the initial Servo AF position
You can manually set the initial Servo AF position when [ : Initial Servo AF pt, /
] is set to [ Initial AF pt set for / ] ( ).
1.
Set the AF method to [ +Tracking] ( ).
2.
Set AF operation to [Servo AF] ( ).
3.
Set the AF point.
To move the AF point (1), use < > or tap the screen.
To return the AF point to the center of the screen, press < > or the
< > or < > button.
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