The Pentax 645 Pro Lens Adapter from FotodioX is an all-metal manual adapter that allows you to use your Pentax 645 lenses with any Hasselblad X-system camera. It features a chrome-plated brass mount for a precise fit, built-in aperture control, an Arca-type compatible lens foot, and is designed to allow focusing to infinity regardless of the equipment used.
This product is useful for mounting lenses that produce image circles large enough to cover medium-sized sensors, which is true of many telephoto models designed for full-frame cameras. It can also be deployed with tilt-shift lenses as an inexpensive way to use your Hasselblad for that kind of photography. Wide-angle lenses, however, will vignette. Please note that this is a manual adapter, and that any electronic communication between the equipment will be disrupted. Lenses with no aperture ring will stop down to their smallest f-stop by default.