This KIPON 0.8x Focal Reducer for Mamiya 645 Lens to FUJIFILM GFX Camera helps to maximize the connected lens's apparent angle of view while providing a 1-stop increase for the camera over the lens's aperture range so that the effective focal length becomes shorter, and the shooting range is larger. With the 0.8x adapter, you have the ability to use medium to smaller format lenses on FUJIFILM GFX cameras.