Nikon D750 DSLR Camera (Body Only) - Manual (Page 387)

359
A
Viewfinder Virtual Horizon
When Viewfinder virtual horizon is selected for Custom Setting f2
( Assign Fn button ) > Press , pressing the Fn button displays a roll
indicator in the viewfinder. Press the button a second time to return to
clear the indicators from display.
Camera tilted right Camera level Camera tilted left
Viewfinder
(camera in
landscape
orientation)
Viewfinder
(camera in
portrait
orientation)
Note that the display may not be accurate when the camera is tilted at
a sharp angle forward or back. For a display that shows both pitch and
roll, use the
Virtual horizon option in the setup menu ( 0 388).