Canon POWERSHOT A650 IS User Manual page 38

I
Various Shooting Methods _103
_ Locking the Flash Exposure Setting
(FE Lock) []
See Functions Available in Each Shooting Mode (p. 214).
You can lock the flash exposure so that the exposure settings are
correctly set regardless of the composition of your subject.
To Release the FE Lock
Operate a button other than the ÷ or "l, button.
The FE lock cannot be used when the auto flash feature is set
to [Off].