So, saw a CL posting for this lens for $525, supposedly glass in perfect condition with front & rear caps, filter (?), and case. Says it's already converted for Canon. From what bit I've seen out on the web (can't take hours to read them all), it looks like a nice lens, and quite interesting and as a MF lens would force me to shoot a bit differently, and likely be a pretty nice portrait lens. So, anyone ever use this lens? Worth buying for that price assuming it's perfect glass as state?