Canon PowerShot SD870IS User Manual page 101

Various Shooting Methods I 99
Changin 9 the AF Frame Size
When the [AF Frame] is set to [Center], the AF frame can be resized
to correspond to the subject. Select [Small] to constrict the focal
frame to suit a small subject or to focus on a particular area of a
subject.
_] he setting is configured to [Normal] when the digital zoom
or digital tele-converter is used.