Oh yes, Alpa 12 is my kind of camera !
So the Rogonar 50mm is no good.
I know from using this lens on a digital sensor that it is very sharp in range f/8 to rf/11 , whereas the Omagaron 1:4.5 90mm I have here is not so sharp across the plane and anyway i need a shorter lens.
My next step is to make a lens bench so I can experiment to find a little lens less than 90mm to do what i indicated in post 25, mounted behind the lens board and that Prontor svs shutter.
I am interested in making a Crayford focuser out of billet alloy, to be mounted in a Graflex lens board. I think I can do it, I suppose the trick will be how to keep it light sealed
Thanks for your help.