Guys, I find this solution damn attractive. I have a scenario for you. What diopter would you use if you had a GH2 and a A7S, a Helios 44, a rare Canon C-8 baby anamorphic lens (2x, similar size to the bolex 8/19) and a Sony 0,7x wide converter? I guess it should be one with a lower value, since only the helios + C-8 already focusses from 50 cm - infinity? Don't know what the extra wideness does to the whole story...