I guess it is about f1.4 or wide open.
All I know is that I wanted the N for the AF, no hands on report though. As a lens nerd you have to get both, Wayne.
The Contax sold within a couple of days to a buyer who already posted a fine image here, but I am not going to say who it is. :-). It is quite normal that people who buy this stuff ask a couple of questions before they throw the money after you.