The jjc canon eos fit reversing ring fits onto your canon eos mount digital slr and is used to turn any brand of lens that features a 77mm filter thread into a macro lens simply reverse your lens so that the mount is facing away from the camera screw onto the jjc reversing ring and start shooting since the lens is fitted backwards there will be no control of the lens via the camera and it is advisable to use a lens that features an aperture ring so that you have more control the jcc reversi