Hi, I've recently found a Switar 25mm 1.4 C-Mount on a local auction site for something like 110 US dollars. I've been investigating about this lens, it seems some people have needed to sand the bottom of the lens to make it fit correctly on a GF1 with an adapter, is this the case? As there are several versions of the Switar 25mm, which one is the "safest"? Any ideas? Would you say 110 US dollars is a good price for this lens? It seems to me ebay auctions for it are quite a bit more $$$... Thanks!