the canon 5d classic has finally arrived - i also ordered a lens converter so i can use my nikon 28mm f/3.5 AI lens https://www.srb-photographic.co.uk/nikon--f-lens-to-eos-adaptor---nikon-lens-to-canon-eos-camera-adaptor-10702-p.asp
the lens adapter seems to work fine - the only quirk is that the distance scale on my lens has to be 'transposed' to get the correct focus distance - if you want to focus on infinity you need to set the lens to about 2 metres, so always set about 1cm to the right on the focus scale to the actual focus distance.
also there is no aperture linkage so you need to focus wide open then stop down to take the photo
i was keen to test the camera however it was evening and light levels were low so i found a willing model as a guinea pig for a test shot or two - i used my fuji flash to take this https://fujifilm-x.com/global/products/accessories/ef-x20/ - i used the lowest possible setting of just 1/64 full power