Adapters that let you mount a lens from one camera system to a body of another are nothing new. Even so-called “Speed boosters” which allow you to get much of the benefit of full frame lenses on crop bodies have been out for a while now. The new Magic Format Converter from Laowa, though, takes things in the opposite direction. Putting smaller format lenses onto larger format sensors.
The adapter gives the ability to mount full frame Nikon and Canon lenses onto the Fuji GFX-50S medium format camera. There are a couple of other adapters out there that can also do this, too, but with one big issue. Nikon & Canon lenses don’t cover the complete GFX sensor. So, your image is cut off at the corners. This adapter compensates by expanding the image out to fill the frame.