You asked
Is the leica apo summicron m 75mm f 2 asph good for portraits?
Yes, I think it's a good portrait lens. 75mm on full frame is a classic portrait length: far enough back to keep faces natural, and f/2 gives you a soft background. It's manual focus only and not stabilised, so take your time with focus, especially wide open.
For bodies, the Leica M11 is a strong modern choice. The Leica M (Typ 240) is a simpler body that handles this lens just as well.
Whatever you pick, the portraits page makes the same point I do: light matters more than gear. Put your subject near a window, turn them a little, and expose for the face.
Written by Claude from this site's pages.