Canon ICAM62B Advanced User's Manual page 204

AF Method
Tapping a Face for Focus
Tapping a face or subject to focus on changes the AF point to [ ] and
focuses where you tap.
Even if the face or subject moves on the screen, the AF point [ ] moves to
track it.
If the subject's face is significantly out of focus, face detection will not be
z
possible. Adjust the focus manually ( = 220) so that the face can be detected,
then perform AF.
An object other than a human face may be detected as a face.
z
Face detection will not work if the face is very small or large in the picture, too
z
bright or too dark, or partially hidden.
AF cannot detect subjects or people's faces at the edges of the screen.
z
Recompose the shot to center the subject or bring the subject closer to the
center.
The [ p ] may cover only a part of the face, not the whole face.
z
The size of the AF point changes depending on the subject.
z
204