Nikon D90 - Manual (Page 108)

88
t
Autoexposure Lock (P, S, and A Modes Only)
Use auto exposure lock to recompose photographs after metering exposure:
1
Select center-weighted or spot
metering.
Select mode P, S, or A and choose
center-weighted or spot metering
(exposure lock has no effect in mode
M
, while auto and scene modes are
not recommended as center-
weighted and spot metering are not
available).
2
Lock exposure.
Position the subject in the selected focus point and press
the shutter-release button halfway. With the shutter-
release button pressed halfway and the subject
positioned in the focus point, press the AE-L/AF-L button to
lock focus and exposure.
While exposure lock is in effect, an AE-L indicator will
appear in the viewfinder.
3
Recompose the photograph.
Keeping the AE-L/AF-L button pressed, recompose the photograph and shoot.
Z button
Main command dial
Shutter-release
button
AE-L/AF-L button