Canon IXUS 1000 HS - Manual (Page 102)

102
You can lock the exposure or change it in 1/3 steps within a range of ±2 before
shooting.
Focus.
● Press the shutter button halfway to focus.
Lock the exposure.
● After releasing the shutter button, press
the
r button to lock the exposure.
The exposure shift bar appears.
● Press the r button again to release
the lock.
Change the exposure.
● While watching the screen, turn the  dial
to adjust the exposure.
Shoot.
● Press the movie button.
● To stop shooting the movie, press the
movie button again.
AE Lock/Exposure Shift