Canon PowerShot SD4500 IS Digital ELPH User Manual page 84

You can change the AF (Auto Focus) frame mode to match the scene you
want to shooL
Choose [AF Frame].
After pressing the MENU button, choose
[AF Frame] in the _ tab, then press the
_ buttons to choose an option.
Face Beteet
Detects people's faces and sets the focus, exposure (evaluative metering
only) and white balance (AWBonly).
When the camera is pointed at subjects, a white frame appears on the face
the camera judges to be the main subject, and gray frames (max. 2) will
appear on other faces.
A frame will follow a moving subject within a certain range.
When the shutter button is pressed halfway, up to 9 green frames will
appear on faces that the camera focuses on.
Center
The AF frame is locked to the center= This is effective for focusing on a specific
point.
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