Purchased this wonderful Carl Zeiss lens from eBay, along with an Arsat 80mm f/2.8, a few weeks ago to experiment with tilt photography on my D90. This is a medium format lens with a Pentacon Six mount. Haven't had the chance yet to take this baby out for a real test drive, but it sure is gorgeous to look at :)
The lens is well-constructed, heavy and solid. Focus is smooth and the aperture ring, snappy. Cliche, maybe, but true. Oh, and that front lens element...it's HUGE! and BEAUTIFUL!
For more information about this lens and test results, please see the following sites: