I used a FotoDiox FD-to-NX adapter to fit this monster Canon FD 400mm 1:4.5 S.S.C. lens on my NX1. I was combing through vintage lenses at a pawn shop in Tucson, Arizona and was just about to walk-out after not finding anything of interest. The guy behind the counter said: "Hey, did you see this one". He reached behind a pile of old cameras and pulled-out this lens. It looked in excellent shape for a 1975 lens, so then I looked at the price -$30!! Are you kidding me?!
Here's a few links to read further about this lens and photographer's comments: