JP 2023-032663 A — Yuki Shibata
| 7 ELEMENTS / 6 GROUPS |
| EFL 29.430 mm MODEL / 29.4 mm PATENT |
| 28 mm / f/2.8 MARKETED |
| F/2.88 PATENT |
| 74.8° MARKETED AOV |
| 2 ASPHERICAL SURFACES |
CONSTRAINED_RECONSTRUCTION — rigid whole-lens unit focus with all internal gaps fixed. The patent publishes a 180 mm object-space state. At the production 0.15 m object-to-image distance, the reciprocal |m| > 1 root is rejected; the branch continuous from infinity gives BF = 51.521596 mm and m = -0.44136 (about 1:2.266).
| Element | Type | Glass |
|---|---|---|
| Lp1 | Positive Meniscus (convex to object) | N-LAF34 (SCHOTT optical equivalent; patent vendor unspecified) |
| L1 | Negative Meniscus (convex to object) | H-FK61 (CDGM optical equivalent; patent vendor unspecified) |
| Ln1 | Biconcave Negative | Unmatched (nd inferred from published FL; νd omitted by patent) |
| Lp2 | Biconvex Positive | TAFD32 (HOYA optical equivalent; patent vendor unspecified) |
| L2 | Negative Meniscus (concave to object) | H-ZF52 (CDGM optical equivalent; patent vendor unspecified) |
| L3 | Positive Meniscus (convex to image) | J-PSKH4 (Hikari optical equivalent; patent vendor unspecified) |
| Le | Positive Meniscus (2× Asph, convex to image) | P-SK60 (SCHOTT optical equivalent; patent vendor unspecified) |