Nikon D800 - Manual (Page 337)

En_03
313
U
!
Viewfinder
virtual
horizon
*
Press the Fn button to view a virtual horizon display in
the viewfinder (see below).
None
No operation is performed when the Fn button is
pressed.
* This option can not be used in combination with Fn button + command
dials ( 0 314). Selecting this option displays a message and sets Fn
button + command dials to None. If another option is selected for Fn
button + command dials while this setting is active, Fn button press will
be set to None.
A
Virtual Horizon
When Viewfinder virtual horizon is selected for Fn button press,
pressing the Fn button displays a pitch and roll indicators in the
viewfinder. Press the button a second time to return to clear the
indicators from display.
Roll
Camera tilted right Camera level Camera tilted left
Pitch
Camera tilted forward Camera level Camera tilted back
Note that the display may not be accurate when the camera is tilted at
a sharp angle forward or back.
Option Description