I contracted to do some portrait photography early December. I am experimenting with the wireless lighting system using my sb-800 and sb-600. I will likely purchase another sb-600 for the shoot. I have set the sb-800 on my d200 as master, and the sb-600 as remote. Everything works perfectly. I also tried setting the Sb-800 to SU-4 mode, and got it and the sb-600 firing off the built-in flash. I was reading the manual and perhaps don't quite understand if there is more to using the flash in SU-4 mode or not. Does that mode just turn the sb-800 it into a remote flash that fires when the master flash fires or are there other functions? Any other suggestions you may have are appreciated. Thanks in advance!