Vintage 6mm f/2.8 fisheye Nikkor lens can see behind itself, sells for $163,000 | Stuff-Review
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
How can nikkor 6mm f/2.8 see behind itself?: Open Talk Forum: Digital Photography Review
Rare Lens] $160,000 Nikkor 6mm 2.8 Fisheye Can See Behind You | Fstoppers
Lens pr0n: The Nikkor 6mm f/2.8 fisheye monster | TechCrunch