Phase One 645 AF - Manual (Page 87)

8.2 Function of the Phase One lens adaptor
To mount the Phase One Multi-Mount, match the white dot on the
camera up with the white dot on the Multi-Mount and turn slowly
clockwise,
NEVER use force to mount the ring. When the Phase
One Multi-Mount is mounted you can fit Carl Zeiss/Hasselblad V and
Hasselblad 200series lenses on the camera.