>I have just added an R1 macro flash, and I'm not yet able to >get it to sync higher than 1/320 with the built-in flash as >Commander. >The D300 won't let me select a shutter speed higher than 1/320 >if the built-in is popped up.
The built-in Speedlight does not support FP High Speed Sync mode. You will need to have an SB-700, SB-800, SB-900, SB-910, or SU-800 in the cameras hotshoe in order to support FP high Speed Sync mode with remote SB-R200, SB-600, SB-700, SB-800, SB-900, or SB-910 Speedlights.
>Per the D300 manual .288 and also the R1 manual it looks like >the R1 supports FP sync at > 1/320.
The SB-R200 (R1) does support FP High Speed Sync mode.
>I have a SB600 available but haven't tested with that flash as >the commander yet.
The SB-600 will support FP High Speed Sync mode when it is in the hotshoe. The SB-600 does not have Commander mode built in so it can only be used on camera as a single Speedlight or as a Remote. You will need an SB-700, SB-800, SB-900, SB-910 or SU-800 to act as Commander.