F4: Assign Ae-L/Af-L Button - Nikon D90 User Manual

f4: Assign AE-L/AF-L Button

Choose the role played by the AE-L/AF-L button. This option is
available in all shooting modes.
.
Option
AE/AF lock
B
(default)
C AE lock only
F AF lock only
E AE lock (hold)
A AF-ON
r FV lock
L
200
Focus and exposure lock while the AE-L/AF-L button is pressed.
Exposure locks while the AE-L/AF-L button is pressed.
Focus locks while the AE-L/AF-L button is pressed.
Exposure locks when the AE-L/AF-L button is pressed, and remains locked
until the button is pressed a second time or the exposure meters turn
off.
The AE-L/AF-L button initiates autofocus. The shutter-release button can
not be used to focus.
Press the AE-L/AF-L button to lock flash value (built-in flash and SB-900,
SB-800, SB-600, SB-400, and SB-R200 flash units only, pg. 198). Press
again to cancel FV lock.
Description