This is my first post here, folks, and I must apologize for my ignorance and if I am spouting absolute nonsense (but I do learn!)
Anyway to cut to the chase, I have a couple of lovely C-mounts, namely Schneider Kreuznach 50/0.95 and Kern-Paillard Macro-Switar 50/1.4 which almost cover the APS-sensor wide open with only a touch of vignetting but vignette more as I stop them down.
I have heard people adapting the Schneider to Leica M8 which is a larger sensor, which got me thinking that perhaps it is the mount opening (which is of course very small in the c-mounts) that gets in the way and whether a change of mount will remove that problem.
I am currently using them on a NEX-5n but if I ever start selling pics I will upgrade to a Leica M14 or whatever it will be in 12 years!
Any insights will be appreciated, in the meantime here are some images I've shot with them recently (only had them for a short time). I hope they showcase what the lenses are capable of to some extent though I know my skill still leave much to be desired.