Canon IXUS 990IS - Manual (Page 87)

87
You can change the metering mode (brightness measuring function) to
match the shooting conditions.
Select the metering mode.
● Press the
m button and select
, then
press the m button.
Select an option.
● Press the op buttons or turn the  dial
to select an option, then press the m
button.
The setting will display on the screen.
When you wish to take several shots with the same exposure, you can set
the exposure and focus separately using the AE lock. AE stands for “Auto
Exposure”.
Lock the exposure.
● Point the camera toward the subject and
press the
o button while pressing the
shutter button halfway.
When
& appears, the exposure will be
set.
● If you release your finger from the shutter
button and press the
o button again, &
will disappear and the AE will unlock.
Compose the scene and shoot.
Changing the Metering Mode
Evaluative
Suitable for standard shooting conditions, including back lit shots.
Automatically adjusts the exposure to match the shooting
conditions.
Center
Weighted Avg. Averages the light metered from the entire frame, but gives
greater weight to the center.
Spot
Only meters within the (Spot AE Point frame) that appears at
the center of the screen.
& Shooting with the AE Lock