Uber-Rare Nikon 6mm Fisheye Lens on eBay Can See Behind Itself | Nikon lens, Fish eye lens, Nikon lenses
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
Nikkor 6mm f/2.8 Fisheye Nikkor lens
Nikon Fisheye Nikkor 6mm f2.8 lens | eBay
Nikon AI Fisheye-NIKKOR 6mm F/2.8 | LENS-DB.COM
Actually Nikon Fisheye-Nikkor 6mm f/5.6: Photographic Science and Technology Forum: Digital Photography Review