I use a TECHART ring to mount Canon EF lenses on the GFX 50S-II and 100S-II, maintaining image stabilization and autofocus. The only limitation are lenses with a small rear element diameter that make it impossible to cover medium format. Fast lenses like the EF 85/1.2L or the 100-400L, however, work great.

I also use a Nikon to GFX Fringer and it works very well.  24mm f/1.8 vignettes so best used on 35mm mode.  50mm f/1.8 covers the entire frame very well with no issues and is a superb little lens. 105mm Sigma vignettes slightly but is perfectly usable. 300 f/4 likewise the 105.  I have a 70-200 f/20+.8 incoming to test so will report back but I'm expecting a little vignetting.  Even in 35mm mode the image is still 60MP and if you're prepared to manually crop and correct you can get 80-90 MP images.  I also have a C/Y to GFX adapter.  The 24mm Sigma Superwide vignettes strongly. Ditto 28-80 Zeiss Sonnar. 80-200 f/4 Sonnar is perfectly usable. All work fine as 35mm mode lenses.  I also have an M42 adapter which I tried with the Carl Zeiss Jena 135mm f/3.5 with good results. 

Thank you. I will research it.

Ahh, the infamous brick wall photos… 😀 According to internet lore, if the dng converter does not properly apply the corrections, you can have it apply custom profiles that should work for you. How to do that is waaaaaay outside of this comment’s scope, but there are plenty of sites listed in the search engines that step you through the processes. Best wishes.

Jerry Thank you very much. That is extremely helpful. It seems that the camera and the lens have the latest firmware update, so it appears that the corrections should be applied automatically. The lens arrived this afternoon and I took some quick test shots, in which the correct lens information appeared in the EXIF files, so that sounds good. I used Adobe DNG converter to convert the Raw (RAF) files, and then opened the DNG files and saved them in PSD format. However, with a beautiful, clear, cloudless blue sky, there were no lines near the edges to check if distortion had been corrected. Another day I plan to photograph a brick wall. Thank you for your help.