Metabones has announced the EF-GFX Smart Expander which features electronic integration and full functionality of Canon EF lenses onto the Fuji GFX medium format camera series in exchange for 1.26 times focal length extension and aperture value.
According to the manufacturer, the Metabones EF-GFX Smart Expander is able to match the image circle of full-frame EF mount lenses to the medium-format sensor of the GFX series cameras (tested specifically with the Fujifilm GFX 50S, GFX 50R, and GFX 100) while allowing the diagonal field-of-view to remain exactly the same. The result is an adapter that sacrifices no functionality, and the GFX will retain full phase-detection autofocus, in-body image stabilization, optical image stabilization via the lens, and a smooth iris.
Referring to that last point, Metabones says that when a lens that supports smooth iris is used, the Smart Expander makes aperture changes quiet and creates smooth transitions by slowing down the electronically-controlled aperture diaphragm. The button on the Smart Expander toggles between auto aperture (programmed exposure or shutter priority) and manual aperture (aperture priority or manual exposure). If a manual lens with no electronics is attached, the button brings up the manual lens selection on the camera body so that focal length can be chosen for correct IBIS operation and EXIF. You can see the list of lenses that support smooth iris here.
Metabones says that the optical design of the Smart Expander consists of five elements in three groups and incorporates an ultra-high index Lanthanum-based optical glass as well as one element made of fused silica. The company says that this formula results in extremely good performance with professional-grade zoom lenses.
That aforementioned 1.26 times focal length and aperture is the only sacrifice photographers will have to make with this adapter according to Metabones. What that expanded focal length and aperture means is that a 24-70mm f/2.8 lens becomes a 30-88mm f/3.5 zoom, and a 70-200mm f/2.8 lens becomes an 88-252mm f/3.5 zoom.
Metabones says that it is most excited about adapting the 11-24mm f/4 from Canon, as they say it becomes “an extremely sharp” 13.8-30.2mm f/5 without any disturbing vignetting or corner aberrations.
The company states that to the best of its knowledge, no one else is producing Fujifilm adapters that support IBIS with every EF mount lens.
In addition to the Smart Expander, Metabones also announced the EF-GFX Smart Adapter, which does not change the focal length or aperture value but in exchange runs the risk of vignetting and degradation of corner performance. There are nine other limitations and known issues with this particular adapter which Metabones lists here.