I need to shoot a large-ish group, and would like to use these flash units for fill (I plan to have helpers hold them). I have the built-in flash (D90) set as commander, and the SB600 CH1 Grp A. I think I'd be using S1 mode (slave without pre-flash). I'm not going to have a lot of time to mess around with settings. What is the best way to set up the YN 560?
