You misunderstand! Nikon deliberately made it so if you mounted, say, the Nikon 200-500mm, to the j5 (via the FT-1) it would show an 'error' message saying you can't use this lens. The theory was it prevented legal claims that fitting eg. a 600mm f4 and picking up the combo via the J5 body, broke the body mount. No kidding! The J5 is no bigger than a back-cap really! I wondered if, as the PF is much smaller and lighter, it's 'allowed'? They had a 'disallowed' list somewhere, but I can't seem to find an updated version!