Nikon D780 Reference Manual page 220

3
Recompose the photograph.
Keeping the A button pressed,
recompose the photograph and
shoot.
A
Metered Area
In [Spot metering] ( 0 166), exposure will be locked at the value metered
in a circle centered on the selected focus point. In [Center-weighted
metering], exposure will be locked at the value metered in a 12-mm circle
in the center of the viewfinder.
A
Adjusting Shutter Speed and Aperture
While exposure lock is in effect, the following settings can be adjusted
without altering the metered value for exposure:
Mode
P
S
A
•
The new values can be confirmed in the viewfinder and control panel.
•
Note that metering cannot be changed while exposure lock is in effect.
174 Shooting Settings
Shutter speed and aperture (flexible program; 0 109)
Setting
Shutter speed
Aperture