http://www.luciolepri.it/lc2/marcoca...ory/00_pag.htm
(Google Translate if you can't read Italian)
The f1.8 Planar does seem like a real gem, it was also called the Voigtlander Ultron. Of course it won't autofocus and you might not be able to focus to infinity. However it's an excellent lens for sure. That said the Canon nifty fifty is a sleeper as well, great piece of glass for the money, in fact I've got one coming my way now ;-)