Canon POWERSHOT SX100 IS User Manual page 30

Various Shooting Methods
I 97
_ Switching between Focus Settings []
See Functions Available in Each Shooting Mode (p. 222).
* In
[] mode
only [Single]
is available.
You can set the AF mode.
The camera only focuses when the shutter button is pressed
Single halfway, conserving battery power.
The camera is continually focusing on whatever it is aimed
Continuous at even when the shutter button is not pressed, allowing you
to shoot without missing opportunities.
1. Use the ÷ or "I, button to select
[Continuous] or [Single].
2. Press the _ button.