US 3,973,832 — Toshinobu Ogura, Akiyoshi Nakamura
| 7 ELEMENTS / 7 GROUPS |
| f = 27.9955 mm (DESIGN) |
| F/2.8 |
| 2ω = 76° (PATENT) |
| ALL SPHERICAL |
Focus travel is not modeled: the patent publishes only the design/infinity prescription. The production 0.3 m minimum focus is metadata; no close-focus optical spacing law is modeled.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | N-SK16 class (coordinate-compatible spectral proxy; native d 1.6214/61.3; supplier/melt unproven) |
| L2 | Negative Meniscus | N-SK16 class (coordinate-compatible spectral proxy; coordinate code 620603; supplier/melt unproven) |
| L3 | Biconvex Positive | S-LAM3 class (coordinate-compatible spectral proxy; coordinate code 717479/480; supplier/melt unproven) |
| L4 | Positive Meniscus | H-LaF3B class (coordinate-compatible spectral proxy; coordinate code 744449; supplier/melt unproven) |
| L5 | Biconcave Negative | SF4 class (coordinate-compatible spectral proxy; coordinate code 755276; supplier/melt unproven) |
| L6 | Positive Meniscus | LAC10 class (coordinate-compatible spectral proxy; coordinate code 720503; supplier/melt unproven) |
| L7 | Biconvex Positive | N-SK16 class (coordinate-compatible spectral proxy; native d 1.6214/61.3; supplier/melt unproven) |