Canon POWERSHOT D20 User Manual page 6

Shooting Range and Focusing
_ Center
One AF frame is displayed in the center. Effective for reliable focusing.
(_ A yellow AF frame is displayed with _ if the camera cannot focus
when you press the shutter button halfway. Note that AF=point
zooming (p. 73) is not possible.
The AF frame size is set to [Normal] when you use the digital zoom (p. 62) or
digital tele-converter (p. 111), and in manual focus mode (p. 109).
8
_ Reeomposing Shots While the Focus is Locked
As long as you keep the shutter button pressed halfway, the focus and
exposure are locked. You can recompose shots as needed before shooting=
This feature is called Focus Lock=
Focus.
Aim the camera so that the subject is
centered, and then press the shutter button
halfway.
Confirm that the AF frame displayed around
the subject is green.
Recompose the shot.
Keeping the shutter button pressed halfway,
move the camera to recompose the shoL
Shoot.
Press the shutter button all the way down.
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