After buying the Sony A7RII, my relationship with C Sonnar ended with momentum. I got rid of the lens. I did not see the point of holding the lens which gives focus only in the center and is very sharp there.
There is no excuse for this, not even portraits. I understood it with the example of 100mm macro lenses. Not suitable for portraits.
I think my CLASSIC HELIAR is sharp enough in the center compared to the C Sonnar and very good in the frame corners.
C Sonnar only provides for 3D POP on F1.5-F2, comparable to the ZM BIOGON 35mm F2, while CA is tragic.
I had two versions of the lens from JAPAN market and US / CANADA market.