Nikon D3S User Manual page 186

Measuring a Value for White Balance
1
Light a reference object.
Place a neutral gray or white object under the lighting that will
be used in the final photograph. In studio settings, a standard
gray panel can be used as a reference object. In exposure
mode h, adjust exposure so that the exposure indicator shows
±0 (0 127).
2
Set white balance to L (Preset manual).
Press the WB button and rotate the main command dial until
L is displayed in the rear control panel.
WB button
3
Select direct measurement mode.
r
Release the WB button briefly and then
press the button until the L icon in
the rear control panel starts to flash. A
flashing D will also appear in the top
control panel and viewfinder. The
displays will flash for about six seconds.
160
Main command dial
Rear control panel
SHOOT
CUSTOM
Top control panel
Rear control panel
Viewfinder