Canon EOS Rebel T1i Instruction Manual page 112

Using AF to FocusN
u (Face detection) Live Mode: c
With the same AF method as the Live mode, human faces are detected
and focused. Have the target person face the camera.
112
Focus the subject.
3
Aim the AF point over the subject,
and hold down the <A> button.
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 red.
Take the picture.
4
Check the focus and exposure, then
press the shutter button to take the
picture (p.106).
Display the Live View image.
1
Press the <A> button.
The Live View image will appear on
the LCD monitor.
When a face is detected, the <p>
frame will appear over the face to be
focused.
If multiple faces are detected, <q>
will be displayed. Press the <U>
key to move the <q> frame over
the target face.