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
Nikon Compendium - The Lenses
6mm f5.6 Fisheye-Nikkor Lens
6mm f/2.8 Fisheye-Nikkor on a Nikon D800 - First Time Ever? - YouTube
Rare Lens] $160,000 Nikkor 6mm 2.8 Fisheye Can See Behind You | Fstoppers
Sample Footage Shot with the Ultra Rare Nikkor 6mm f/2.8 that Can See Behind Itself | PetaPixel
Nikkor 6mm f/2.8 Fisheye Nikkor lens
Ridiculous Nikon 6mm Lens Reappears, Priced at $160,000+ in the UK | PetaPixel
Camera Geekery: The Nikkor 6mm f/5.6 Fisheye Nikkor aka The Holy Grail - Japan Camera Hunter
Nikkor 6mm f/2.8 Fisheye Nikkor lens
Deal of the day: Nikon Fisheye-Nikkor 6mm f/5.6 circular fisheye lens for $5,999 - Nikon Rumors
Nikon 6mm f/2.8 Lens for Sale in UK... on Craigslist | PetaPixel
Nikon Fisheye Nikkor 6mm f/2.8 Lens
Nikon 6mm F/2.8 Fisheye Lens Eğlenceli olsa gerek :) ( Profesyonel Fotoğrafçılık ) - YouTube