Custom Setting #E1 Flash Top Sync Speed - Nikon D300 Complete Manual

Recommendation:
1. There's not a lot of reason to choose anything other than
the default, as you have to take the MB-D10 off if you use
the batteries in the camera first and want to recharge
them. The best case scenario for using the alternative
setting I can think of is that you've put non-rechargeable
AA batteries in the MB-D10 and want to save them as the
last resort.

Custom Setting #E1 Flash Top Sync Speed

(Flash sync speed)
Nikon allows you to adjust the flash sync speed on the D300
downward from its normal setting, plus set to "faster" sync
speeds:
1/320 (Auto FP) 1/320 second lower limit, plus TTL FP
1/250 (Auto FP) 1/250 second lower limit, plus TTL FP
1/250
1/200
1/160
1/125
etc.
Thom Hogan's Complete Guide to the Nikon D300
with external Speedlights at shutter speeds
over 1/320
with external Speedlights at shutter speeds
over 1/250
1/250 second lower limit [default]
1/200 second lower limit
1/160 second lower limit
1/125 second lower limit
V1.02
Page 560