Taking lens recommendations 5d mk III + Kowa 16H In: ANAMORPHIC Posted May 8, 2014 · Report reply Unfortunately we dont have the Kowas right now to confirm, but the Helios 58mm was giving us little vignetting. After looking at our video and the notes, the Canon 50mm lens that was mentioned in the posting was an FD lens. So there was a crop factor introduced via the FD to EOS adapter which is why we had minimal vignetting. I'm not sure exactly how strong of a crop. We dont have video of the Kowa with the Nikon 50mm f1.8, but there was probably more vignetting vs the Canon FD lens as I dont think the Nikon converters introduce a crop.