I am the proud owner of a San Giorgio Janua. Although commonly seen as a 'Leica copy', it is a class in it's own. It has its own mount which is not threaded but muonted with a lock, similar to an M. Build quality is really superior. The Essegi lens seems to be equal in quality to an elmar 50. It also has a build in extinction meter, and a dioptry corrected finder. Speeds go up to 1000. Mine came in superb condition with its ERC. The ones offered for sale on ebay carry really high prices (3000 $ +) but I don't know if they really sell for this.