US 4,203,653 — Ikuo Mori
| 5 ELEMENTS / 5 GROUPS |
| f ≈ 28.0 mm |
| F/2.8 |
| 2ω ≈ 74° |
| ALL SPHERICAL |
Unit focus (assumed): the whole five-element unit moves forward and only the back focus changes, from 36.25 mm at infinity to 38.10 mm at 0.5 m. The patent publishes the infinity state only; the close state is a paraxial reconstruction for the manufacturer's 0.5 m minimum distance, measured from the film plane as on all Nikonos lenses.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | 670575 — lanthanum crown (J-LAK02 HIKARI / S-LAL52 OHARA coordinate-compatible, Δnd −0.0003; supplier unconfirmed) |
| L2 | Biconvex Positive | 603425 — barium flint (K-BaSF5 SUMITA class; supplier unconfirmed) |
| L3 | Biconcave Negative | 785261 — dense flint (SF56A SCHOTT / ZF51 CDGM class; supplier unconfirmed) |
| L4 | Positive Meniscus | 804466 — lanthanum dense flint (J-LASF015 HIKARI / S-LAH65V OHARA class; supplier unconfirmed) |
| L5 | Positive Meniscus | 732510 — lanthanum crown (nearest LAKN12 SUMITA, Δnd +0.0015; TAC4 HOYA alternate, Δnd +0.0020; supplier unconfirmed) |