The WRS-M645 allows you to mount lenses from the Mamiya 645 series, in combination with the WRS (or Wide DS) series camera and Phase One XT bodies.

It also accepts Schneider Kreuznach Blue Ring lenses, There's no electronic connection. So it's open-aperture only, or you'll need to stop down the lens on a Phase One XF body first.

This combination will work with those digital backs that have a built-in ES-shutter (sensor activated electronic shutter), which work as shutterless digital back, such as the PhaseOne IQ3 100MP and the IQ4 series.

The aperture of the lenses can be set manually, the shutter (if applicable) needs to stay open.

The practical use of lenses may be limited to those that have enough image circle coverage for the used digital back when using shifts.

The use of Mamiya 645 lenses from the ProTL system allows for a manual aperture setting.

The use of the later lenses of the DF and XF system is mechanically possible, but there is no communication between the lens and the camera body. This means that electronically set apertures can NOT be controlled.