Nikon D3S User Manual page 344

A
Virtual Horizon
When Virtual horizon is selected for Fn button press, the exposure
indicators in the viewfinder and top control panel can be used as a
horizontal level. Press the Fn button to toggle between exposure and tilt
meter displays.
Control panel
Viewfinder
Note that the display may not be accurate when the camera is tilted at
a sharp angle forward or back.
Fn button + command dials
Selecting Fn button + command dials for Custom Setting f4
displays the following options:
Option
Choose
i
image area
U
318
Camera tilted right
Press the Fn button and rotate
the main command dial to
highlight the desired image
area (0 78); press 2 to select
or deselect. Highlight Done
and press J when settings
are complete.
Camera level
Description
Camera tilted left