JP 2021-179551 A — Takahiro Kitada, Yuka Kudo, Masashi Sueyoshi, Jindong Li
| 11 ELEMENTS / 9 GROUPS |
| f = 20.8–57.6 mm |
| F/3.57–5.81 |
| 2ω ≈ 93.4–40.6° |
| 4 ASPHERICAL SURFACES |
| 3 ED, 1 UHR |
Inner focus via G4 (L10). L10 translates toward image for close focus; close-focus spacings are inferred from paraxial finite-conjugate matching because the patent publishes only infinity-focus data. Production MFD is 0.15 m (at 20–26 mm) and 0.40 m (at 60 mm), max magnification 0.43× at 26 mm.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | S-BAL35 (OHARA) |
| L2 | Negative Meniscus | S-LAH95 (OHARA; exact patent coordinate match) |
| L3 | Biconcave Negative | FCD515 (HOYA) |
| L4 | Biconvex Positive | 859300 - high-index flint (patent nd=1.85883, vd=30.0) |
| L5 | Biconcave Negative | J-LASF021 (Hikari) |
| L6 | Pos. Meniscus (2× Asph) | K-VC89 (Sumita) |
| L7 | Biconvex Positive | S-FPL51 (OHARA) |
| L8 | Plano-Concave Negative | NBFD15 (HOYA) |
| L9 | Biconvex Positive | S-FPL51 (OHARA) |
| L10 | Biconcave Negative (2× Asph) | M-BACD12 (HOYA catalog equivalent; production supplier unspecified) |
| L11 | Positive Meniscus | PBH21 (OHARA discontinued catalog-equivalent to patent 923209; supplier not identified) |