Nikon filed a patent (P2018-17857A) in Japan for a 400mm f/5.6 (22cm long), 500mm f/5.6 (28cm long) and 600mm f/5.6 (33cm long) full frame Phase Fresnel (PF) lenses. Addition information on Nikon Phase Fresnel (PF) lenses can be found here: Nikon’s Phase Fresnel (PF) lens explained As of today the Nikkor 300mm f/4E PF ED VR is the only … Continue reading The latest Nikon patents: 400mm, 500mm and 600mm f/5.6 Phase Fresnel (PF) lenses