Lensfinder.com - Ultra Rare Nikkor 6mm f/5.6. Only a few hundred of these lenses exist. This lens has a 220 degree field of view for Full Frame 24x36mm sensors. Made in Japan
Ridiculous Nikon 6mm Lens Reappears, Priced at $160,000+ in the UK | Nikon lens, Nikon lenses, Fish eye lens
Lens pr0n: The Nikkor 6mm f/2.8 fisheye monster | TechCrunch
Rare Nikon 6mm f/2.8 Lens Listed on Yahoo Auctions for 13 Million Yen - Resource
The remarkable Nikkor 6mm f/2.8 Fisheye - Japan Camera Hunter
Huge 11-Pound Nikon 6mm ƒ2.8 Fisheye Lens Goes On Sale | Cult of Mac