CV 50/1.1: in practice, I haven't found focus shift to be an issue (I believe I have a good copy) and it's definitely sharp at f/2.8, with perhaps some corner weakness. If you don't mind the bulk and are after a fairly neutral rendering, this may be a good choice. The (now discontinued but still available) CV 50/1.5 may be an even better choice, but I have only briefly tested a bad (decentered) copy in the past and can't provide meaningful impressions.