Canon EOS Rebel SL1 18-55mm IS STM Kit Instruction Manual page 78

Using AF to Focus (AF Method)
If the subject's face is significantly out of focus, face detection will not be
possible. You can prevent this by setting [Continuous AF] to [Enable].
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.
78
You can also tap the LCD monitor
screen to select the face or subject. If
the subject is not a face, <
displayed.
If no faces can be detected, or if you
tap the LCD monitor but do not select
any face or subject, the camera will
switch to [FlexiZone - Multi] with
automatic selection (p.79).
Focus the subject.
3
Press the shutter button halfway to
focus.
When focus is achieved, the AF point
will turn green and the beeper will
sound.
If focus is not achieved, the AF point
will turn orange.
Take the picture.
4
Check the focus and exposure, then
press the shutter button completely to
take the picture (p.74).
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