I have for sale a 180mm f2.8 Carl Zeiss Sonnar with mount for Pentacon 6 or Kiev 66. The lens is is beautiful condition cosmetically but the diaphragm will not stop down. I had the same problem some years ago and had it repaired but from lack of use it is now stuck again. The diaphragm could be easily repaired but I no longer have a camera that accept the lens so I am offering it at a "AS IS" price of $50 plus shipping. At that price it would make a wonderful portrait lens for use wide open even with no repair!! This is a big piece of glass so I am thinking that shipping would be about $15.