Those look very fun. I don't have one, but my similar camera is the Horseman Convertible. It can take any Horseman film back (most of mine are 6x9, but 6x7 and 6x6 also available.) It has a 62mm lens, that is exchangable, but Horseman never made any other lenses for it. Rather than a viewfinder, there is a "eye positioner" (my name) in the cold show, and a pull up metal frame. Open both up, nool through the eye positioner, and the pull up frame marks the extend of the 6x7 62mm point of view.