A new patent application surfaced online in Japan yesterday (P2022-21154A) for a NIKKOR Z 85mm f/1.2 lens. Several different designs are described in the patent plication – see the diagrams above. Here are the details for the #1 lens design:
Focal length (f): 84.7mm
Aperture (FNO): f/1.22
Angle of view (2ω): 28.42°
Image height (Ymax): 21.60mm
Overall length (TL): 134.82mm
Back focus (BF): 11.46mm
What’s most interesting is that the purpose of the patent is to build a lens with defocus control (control of the spherical aberration), like the older Nikon AF DC-Nikkor 105mm f/2D and Nikon AF DC-NIKKOR 135mm f/2D, and the Canon RF DS lenses (Defocus Smoothing).
Indeed, paragraph 57 [Summary] begins as follows (translated):
“[Problem] To provide an optical system which has a plurality of focusing states with different aberration amounts at a given shooting distance and which can control a given aberration amount without affecting the focusing.”
Other key points of the numerical examples described in the patent application include:
Extremely low axial dispersion, which can be considered to be at apochromatic level from f/2 onwards.
Low contrast at the edges of the frame at f/1.2, suitable for portraits.
Very high resolution in the central area once stopped down to f/2.
The path of the light rays is quite strongly deflected by the last biconvex lens before the iris (L17 in the lens diagrams). Achieving nominal performance will require very careful assembly in this area.
I have more than a dozen other new Nikon patents I need to report on – stay tuned.
Via Hi-lows-note (thanks to Mistral75 for the details)
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