New Nikon NIKKOR Z 85mm f/1.2 S lens patent (with defocus control?)

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.

The NIKKOR Z 85mm f/1.2 lens (S-line) is on the latest Nikon mirrorless lens roadmap and I expect the lens to be announced soon (maybe even this month at the CP+ show in Japan):

Updated Nikon NIKKOR Z lens roadmap (January 2022)

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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