#2. "RE: Can I use a sb-80dx in slave mode with a D700?" In response to Reply # 1
Ok, adding some more findings. I remembered one thing, and that is CLS and SU-4 do not work together. The preflashes from the camera or SB-800 commander will set off the SB-80 before the other flash unit(s)go off.
So it's all SU-4 or CLS, not a combination of the two. Or go with Pocket Wizards.
#3. "RE: Can I use a sb-80dx in slave mode with a D700?" In response to Reply # 0
The SB-80DX has a built in optical slave mode that can be set to non-TTL Auto mode or Manual flash mode. The D700's built-in Speedlight or on camera Speedlight must be set in Manual flash mode or non-TTL Auto flash mode. I would also recommend having the camera in Manual exposure mode and Manual ISO as well. Good Luck and Enjoy your Nikons!