I was reading a book on close up and Macro Photography and saw that he author suggested a Canon 500D close up lens. I have a nice Macro lens for both my Canon and my Oly but did not have one for my Pentax and wondered, since this is a sort of filterlike lens that screws into the filter grooves on the lens,could this be used on my Pentax or can it only be used on a Canon?
thank you
maria

