Second hand BPM mount converter Bellows Interchangeable Mount for sale.
Used Rare mount converter has screw clamps to attach a male and female pair of BPM bellows adaptors/mounts so a lens of one fitting can be attched to a camera of another. You may want to use a Contax Lens on an Olympus body or a Pentax lens on a Canon body. Any camera/lens combination can be used providing there's a BPM adaptor made. Very hard to find item. Infinity is lost because the adaptor mounts create around 25mm or so extension.