The newly released Fujifilm GFX 50S has a sensor slightly larger than the standard 35mm full frame sensor. When full frame Canon/Nikon lenses are used with Fujifilm GFX, there is a possibility that serious vignetting may occur, especially for wide angle lenses.
Our patented 5 elements in 4 groups optics system inside the Laowa Magic Format Converter (MFC) can enlarge the image circle of your Canon / Nikon full frame lens and allow it to use with Fujifilm GFX cameras without vignetting.
The aperture dial on Nikon F/G adapter is designed to provide aperture control for Nikon G-type lenses, which do not have an aperture ring. No such feature on Canon mount.