Canon 0296B002 Digital Camera User Manual

AE lock enables you to lock the exposure at a different place from the
point of focus. After locking the exposure, you can recompose the shot
while maintaining the desired exposure setting. This is called AE lock. It
is effective for backlit subjects.
Focus the subject.
Press the shutter button halfway.
The exposure setting will be displayed.
Press the <A> button. (0)
X <A> lights in the viewfinder to
indicate that the exposure setting is
locked (AE lock).
Each time you press the <A> button,
it locks the current exposure setting.
Recompose and take the picture.
If you want to maintain the AE lock
while taking more shots, hold down
the <A> button and press the shutter
button to take another shot.
AE lock indicator
If One-Shot AF or AI Focus AF (when not AI Servo AF) is set, pressing
the shutter button halfway to focus will automatically set AE lock at the
same time.
The AE lock effect will differ depending on the AF point and metering
mode. For details, see “AE lock” (p.160).