I have a Sigma ring flash (dedicated to Canon EOS). Works pretty well, but I don't do much stock stuff with it. I picked it up in a bankruptcy camera store auction very cheaply. I don't think it would get enough use to warrant paying full price - I find I get better more interesting light using an off camera flash - the ring flash is pretty flat front on lighting, even with the sides of the flash set at different strength - but at least the ring flash can be used as a combination of fill and a master to fire my Sigma DG super which is my main flash, so it's useful that way.