I am looking for a 35 lens for a IIIf and am finding a few choices. Interested in a lens of modest size and weight for general use. Price is not a big issue, and while it doesn't need to be the absolute optically best lens available, I'm not interested in a Russian lens or something of equally inconsistent quality. So far I have seen a Summaron f3.5, a Canon Serenar f3.5, and a Canon f2.8, and wonder how they compare. Please let me know your comments or suggestions.