I managed to find one of these guys in excellent shape, with the front conversion element, and was lucky enough to get a Nikon F adapter for it from Michio. It is crazy sharp. Here are a few pix I did with it. Luckily it is optimized for 1:20 (or 1:40 with the front element), so it seems to work well at longer than normal macro distances. The water drop falling into the Japanese fountain was a lucky shot (obviously), but what is amazing is that this is about a 4-5x crop, just so you can gauge how sharp the lens really is.