I have, and LOVE, a 40mm Distagon. The lens is pretty much pure magic for me. The only complaint I have ever had for it is the lack of filter options. Actually, at this point the only filter I REALLY REALLY want for it is a polarizer. Heliopan will make one, but I'm not going to drop $685 on a filter...that's a large chunk towards a superwide--and those take a "normal" filter size. The Bay 104 stuff does come up on eBay from time to time, but they usually go pretty high. I was able to find the front cover on eBay, as well as the leather case. Again, I have to say that this is a magical lens.