Originally Posted by Canada_Rockies 
But it will crop the subject by 1.7, which might be what was meant. My next project will be to see how it works with my M 100 macro. It might just give me an edge. A 170mm f/6.8 macro lens, all Pentax glass.
of course it crops by 1.7x after all it is a teleconverter, to my knowledge there is no 1:1 autofocusing adaptor for any camera. It needs to have magnification because im the adaptor changes the mount to focusing plane distance.
as for the SMC-M100 F4, it works just fine, I have one.