Sony CYBER-SHOT DSC-S750 Instruction Manual page 36

Shooting menu
z If the subject is out of focus
When shooting with the subject at the edge of the frame (or the screen) or when using [Center AF], the
camera may not focus on a subject at the edge of the frame.
In such cases, do as follows:
1 Recompose the shot so that the subject is centered in the AF range finder, and press the shutter
button halfway down to focus on the subject (AF lock).
As long as you do not press the shutter button fully down, you can retry the procedure as many
times as you want.
2 When the AE/AF lock indicator stops flashing and remains on, return to the fully composed shot,
and press the shutter button fully down.
36
AE/AF lock indicator
AF range finder frame
For details on the operation 1 page 30