How large a group? At weddings I use an SB800 on camera and an SB600 on a stand, I can do a dozen people that way just fine at ISO400. I'll hand hold down to 1/30 for some ambient, or might use a tripod, depends on the room. I will not bump up a large group past ISO400, large group = large print. Edit: I'm using a Nikon D2x.
I shot my parents-in-law's 50th wedding anniversary gathering with a Cirkut camera, but I don't think you meant something like that.
