There is a problem with the AF confirm. When I put the ring the unit is not working and displays an error message saying it does not recognize the objective and I have to update the database of objective (I use a Canon EOS M). As I do not care to have the AF confirmation I put scotch tape on the switch for the device does not recognize the ring and now it works fine. I will try on another of my devices and if I am the same shot, I'll definitely turn contactors with a large screwdriver and a hammer. Waiii!