Nikon D300 User Manual page 768

familiar. CLS is willing to oblige those experienced in
working manually.
▪ -- Mode (double-dash mode) – The built-in Speedlight
will not fire the main flash burst in this mode. It will fire
the monitor pre-flashes, since it uses them to determine
exposure and communicate with the external flash
groups. Be sure you always raise the camera's built-in
flash in any of the
the external flash groups will not receive a signal and
won't fire their flashes.
Since the built-in flash's monitor pre-flashes always fire, be
careful that they do not influence the lighting of your image.
Use a smaller aperture, or move the camera farther away from
your subject if the pre-flashes add unwanted light.
When you set the
mode, that entire group of flashes will not fire any flash
output. You can use this mode to temporarily turn off one of
the flash groups for testing purposes.
Setting the Channel (CH) for
Communication
Look at Figure
screen, and you'll notice that just below
Channel (CH) selection. The number
communication channel your D300(S) expects to use to talk
to the external flash groups.
There are four channels available, just in case you happen to
be working in the vicinity of another Nikon user who is also
Commander mode
Mode for Group A
12-12, or your camera's
768
modes; otherwise,
or B to double-dash
Commander mode
Group B
1 (factory default) is the
(- -)
there is a