My camera is TTL (Nikon N90s), but for the 555 you need the appropriate TTL module installed, which I do not have. I have a remote sensor for the Vivitar 283, which is quite respectable, but I really like the Sunpak - more battery power and more accurate sensor. I suppose the alternative would be to take some flash readings with a flash meter before the show, and then dial the Sunpak on manual. The problem is that the ambient light is typically different before the show (full house lights etc) and I'm not sure if that would affect the flash meter's reading. Also it would not be practical to change settings during a runway walk to accommodate pictures at different distances.