US 4,124,276 — Yukio Okano, Akiyoshi Nakamura, Toshinobu Ogura
| 6 ELEMENTS / 5 GROUPS |
| f ≈ 85.0 mm (production) · 100.0 mm (patent) |
| F/2.8 |
| 2ω ≈ 28° |
| ALL SPHERICAL · VARIABLE SOFT FOCUS |
Inner focus — Group AI (L1–L4) moves forward; AII (L5) and B (L6) remain stationary. Separate 4-position click-stopped ring varies d_B0 for soft-focus control.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | 749501 - lanthanum crown (catalog unresolved) |
| L2 | Biconcave Negative | S-TIM27 (OHARA) |
| L3 | Negative Meniscus | S-TIL2 (OHARA catalog equivalent; patent code 541468, supplier unspecified) |
| L4 | Biconvex Positive | 720521 - lanthanum crown (catalog unresolved) |
| L5 | Positive Meniscus | S-LAL14 (OHARA) |
| L6 | Negative Meniscus | FL57 (HOYA catalog-equivalent; patent supplier unspecified) |