Douglas, I had a Contax 135 f:2.8. My take: Pros = small and light (for a metal construction lens), easy to use (for an MF lens), lovely colours and mild rendering, low price. Cons = lots of CA, so-so sharpness only, not a lot of detail. Conclusion = nice at first sight, mildly disappointing soon after. Not at all typical of a Zeiss lens.