US 4,094,588 EXAMPLE 1 — NAKAGAWA / OLYMPUS
| 7 ELEMENTS / 6 GROUPS |
| f ≈ 50.0 mm |
| F/1.4 |
| 2ω ≈ 46° |
| ALL SPHERICAL |
Unit focus — entire optical assembly translates forward as a rigid unit.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | SK16-type (Schott SK16 / HOYA BACD5 — exact) |
| L2 | Positive Meniscus | LaK-type A (694-508; no exact current catalog match — likely discontinued OHARA or HOYA formulation) |
| L3 | Negative Meniscus | BaF-type (581-408; OHARA S-TIM25 family — close) |
| L4 | Biconcave Negative | SF4 (Schott SF4 / OHARA S-TIH4 — exact) |
| L5 | Biconvex Positive | LaK-type B (694-533; same nd as L2/L7 but higher νd — no exact current catalog match) |
| L6 | Positive Meniscus | LaSF3 (Schott LaSF3 / HOYA NBFD3 — exact) |
| L7 | Biconvex Positive | LaK-type A (694-508; same glass as L2) |
Detailed analysis available in the interactive viewer above.