I have a 80mm Rodenstock Rodagon-P that is an F4, but has a hex head screw in it to fix it at F7. It seems to be factory and not someone's personal hack and can be removed, but you would need to replace it with some sort of lever to move the iris around. I also have a 80mm F5.6 Rodenstock Rodagon if that is of interest. Pm for pics if these suit or needs.