Konica Reflex Hexanon ARM 1000mm f/8

It is believed that no more than one to two dozen of these lenses were ever sold. The price at the time would buy a modest car.

This large "mirror" lens uses a rear mounted bellows type focusing mechanism.

It and the larger 2000mm Reflex Hexanon are unique among "mirror" lenses, having some form of aperture control. At the rear is mounted a disc with, effectively, Waterhouse stops (various size holes) in it. It can be dialed into place, to achieve different aperture settings.