Nikon 5000 - Manual (Page 120)

Taking Photographs—Advanced Photography
106
Locking Exposure: Spot and Center-Weighted Metering
When spot or center-weighted metering is selected, pressing the shutter-re-
lease button halfway sets exposure for the subject at the center of the frame.
If your subject is not in the center of the frame when the shutter-release but-
ton is pressed halfway, exposure will be set for an object in the background,
with the result that your intended subject will be over- or under-exposed. In
this situation, autoexposure lock can be used to lock exposure after metering
your main subject, allowing you to adjust the composition before taking the
photograph.
1 Set focus and exposure
After positioning your subject in the center of the frame, press the shutter-
release button halfway and check that the green lamp next to the viewfinder
lights, indicating that the subject is in focus.
Options for the AE-L/AF-L Button
By default, pressing the AE-L/AF-L button when the camera is in focus locks
both focus and exposure. In User Sets 1, 2, and 3, the Controls > AE-L, AF-L
option in the setup menu (
150) can be used to set the AE-L/AF-L button
to lock only one of focus or exposure.
2 Lock exposure
With the shutter-release button pressed half-
way, press and hold the AE-L/AF-L button.
Focus and exposure will remain locked as long
as the AE-L/AF-L button is pressed, even if you
remove your finger from the shutter-release
button.