Viltrox EF-GFX Lens Mount Adapter for Canon EF or EF-S-Mount Lens to FUJIFILM G-Mount GFX Camera

I don't recommend this adapter for anyone hoping to use it with a Fuji GFX 100 S with Canon lenses. It focuses erratically with both old and new Canon L lenses. You cannot focus manually even if you turn the auto focus off on the lens itself. The worst part is that you cannot get any technical support. I have used other adapters from Fotodiox for converting my canon 5DSR lenses to Canon R5, It works flawlessly. I will return the Viltrox and try the adapter from Fotodiox.

This adapter works well on my GFX 50S II. The auto focus of my Canon lenses is almost as fast as native lenses. Now I have more lenses to use on my GFX camera.

I have the GFX 50S II and a few ZEISS Milvus ZE (Canon EF mount) lenses, so I wanted to try these on the medium format and see how bad the vignetting was. As expected, the wider the lens, the greater the vignette. Shooting the GFX 50S II with the Viltrox EF to GFX adapter and a ZEISS Milvus 50 ZE (Canon EF): shot my laptop screen with a mid-grey desktop from about 12" at four exposures decreasing from 0 in stop increments in three formats: 1:1, standard 4:3 and the GFX's "35mm mode." This latter mode decreases the width and height to a 3:2 ratio. Pixel dimensions: 1:1 image 6192 x 6192 4:3 image 8256 x 6192 (standard format for GFX) 35 format 6768 x 4512 I wondered why the 35mm mode didn't use the full width of the sensor (8256 pixels), but then the vertical dimension in 3:2 ratio would be 5504, and probably this would include vignetting, so they decreased the width. (I tried to upload three images of the grey screen but kept getting an error!) In real world shooting, sometimes a vignette is acceptable, or added after in post. I have attempted to reduce the vignette in both Photoshop CC and Affinity Photo, and neither does a great job because the vignette is too strong, too well defined. So using this adapter I'll either shoot 1:1 or in 35mm mode on the GFX. My one quibble is that I am dubious about the long-term robustness of this adapter. Although there's no wobble when attached, dismounting you have to be careful. I would advise to mount adapter first, then the lens, and the reverse when removing. Especially with heavy lenses like the Zeiss series.

Got this to use my canon EF lenses with my GFX 50r. You can mount the lens but cannot control aperture and the AF focus is not acceptable. Had to return the item.