I have trying to figure out this mount type. I got this from my dad who bought in the 70s for his OM-1 Olympus. Got it home and to his dismay it was not the right mount. As you can see in the photos. It looks like some type of inset screw mount. Other then that I have no clue as to what it is. Its a Auto Tamron Zoom 70-220mm 1:4 with unknown mount.