Nikon autofocus speedlight SB-900 User Manual page 50

Batteries
Standby function to conserve battery power
C
To cancel Standby
• Turn the [Power ON-OFF/wireless setting] switch to [ON], [REMOTE] or [MASTER].
• Press the [Test firing] button.
• Press the camera's shutter release button halfway.
Adjusting the lead time before the Standby function is activated
• The lead time before the Standby function is activated can be adjusted by
custom setting (kC-23).
C–28
If the SB-900 and the camera are not used for
more than a specified time, the Standby function is
automatically activated to conserve battery power.
• The Standby function activates when the camera's
exposure meter is turned off (default setting).