Canon EOS M Basic Instruction Manual page 231

One-Shot AF for Still Subjects
Suited for still subjects. When you press the shutter button
halfway, the camera will focus only once.
When focus is achieved, the AF point will turn green and the beeper
will sound.
With evaluative metering (p.151), the exposure setting will be set at
the same time focus is achieved.
While you hold down the shutter button halfway, the focus will be
locked. You can then recompose the shot if desired.
If [53: Beep] is set to [Disable], the beeper will not sound when focus is
achieved.
Servo AF for Moving Subjects
This AF operation is suited for focusing moving subjects. When
you first press the shutter button halfway, the camera will focus
and the AF point will be fixed. While you hold down the shutter
button halfway, the camera will keep focusing the subject.
The exposure is set at the moment the picture is taken.
During continuous shooting, the AF operation for shots after the first
one is as follows.
• When an EF-M lens is attached: the camera will continuously focus
the subject.
• When an EF or EF-S lens is attached: Focus lock will be used.
When an EF or EF-S lens is attached, setting the [AF method] to
[FlexiZone - Single] is recommended.
Depending on the shooting conditions, it may take a moment until
the shutter is released.
f: Changing the Autofocus OperationN
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