Canon EOS M Instruction Manual page 119

If the focus is far off, face detection will not be possible. If you set
[Continuous AF] to [Enable], you can prevent the image from becoming
greatly out of focus.
An object other than a human face may be detected as a face.
Face detection will not work if the face is very small or large in the
picture, too bright or too dark, or partially hidden.
The <p> may cover only part of the face.
When you press the <XL> button, the <
center of the screen. Drag it to move the AF point. Press the <XL>
button again, and the AF point will move to the detected subject. button again, and the AF point will move to the detected subject. button again, and the AF point will move to the detected subject.
Since AF is not possible with a face detected near the edge of the Since AF is not possible with a face detected near the edge of the Since AF is not possible with a face detected near the edge of the
picture, the <p> will be grayed out. If you press the shutter button > will be grayed out. If you press the shutter button > will be grayed out. If you press the shutter button
halfway, the subject will be focused in FlexiZone - Multi method with
automatic selection.
Changing the Focusing Method
> AF point will appear at the
in FlexiZone - Multi method with in FlexiZone - Multi method with
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