Canon EOS-1D C Instruction Manual page 218

Using AF to Focus
Quick Mode: f
The dedicated AF sensor is used to focus in One-Shot AF mode (p.67),
using the same AF method as with viewfinder shooting.
Although you can focus the target area quickly, the Live View image
will be interrupted momentarily during the AF operation.
In AF area selection modes other than 61-point automatic selection AF,
you can manually select the AF point or zone.
Area AF frame
Magnifying frame
218
Display the Live View image.
1
Press the <A> button.
The Live View image will appear on
the LCD monitor.
If the AF area selection mode is set to
"61-point automatic selection AF", the
Area AF frame will be displayed.
In other modes, the AF point will be
displayed as a small frame.
The larger rectangular frame is the
magnifying frame.
Select the AF area selection
2
mode.
Press the <S> button.
Each time you press the <B>
button, the AF area selection mode
changes.