This is an excellent simple to use piece of equipment. It features a rotating base for the flash unit and a light sensor on a swivelling barrel allowing great freedom of placement for the secondary flash. A diffuser for the built-in flash of the Nikon D50 allows a softer light emisson although the SU-4 is at its best with the SB 800 as the master unit and the SB 600 mounted on the Su-4 itself. Although the SB800 and SB600 flash units feature the TTL integrated lighting system the Su-4 takes all the hard work away from adding a second or third flash unit