Nikon Z 9 Reference Manual page 650

Role
[AE/AWB lock
O
(hold)]
[AE lock (Reset
D
on release)]
C [AE lock only]
B
[AE/AF lock]
r
[FV lock]
[ c Disable/
h
enable]
q
[Preview]
A Custom Settings: Fine-Tuning Camera Settings
650
Exposure locks when the control is pressed. White
balance will also lock provided [Auto] or [Natural
light auto] is selected for white balance. Exposure
and white-balance lock do not end when the
shutter is released. The lock will however be
released when the control is pressed a second
time or the standby timer expires.
Exposure locks when the control is pressed.
Exposure remains locked until the control is
pressed a second time, the shutter is released, or
the standby timer expires.
Exposure locks while the control is pressed.
Focus and exposure lock while the control is
pressed.
Press the control to lock flash value for optional
flash units; press again to cancel FV lock.
If the flash is currently enabled, it will be disabled
while the control is pressed. If the flash is currently
off, front-curtain sync will be selected while the
control is pressed.
While the control is pressed, the shooting display
will show how color, exposure, and depth of field
are affected by current photo settings.
Description