Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 318)

AF Operation
One-Shot AF for Still Subjects
AI Servo AF/Servo AF for Moving Subjects
AF Status Indicator (Viewfinder Shooting)
You can select the AF operation characteristics to suit the shooting conditions or subject.
1.
Set the lens's focus mode switch to < >.
2.
Press the < > button ( ).
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