US 3,994,574 — Jihei Nakagawa
| 8 ELEMENTS / 7 GROUPS |
| f = 23.99995 mm |
| F/2.8 |
| 2ω = 85° PATENT CURVES / 84° PRODUCTION SPEC |
| ALL SPHERICAL |
Non-patent unit-focus model: the complete optical assembly translates toward the object; the patent publishes only the infinity prescription.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus, convex to object | S-LAL14 (OHARA; modern equivalent of legacy 697/556 class) |
| L2 | Negative Meniscus, convex to object | S-TIM3 (OHARA; modern equivalent of legacy 613/370 class) |
| L3 | Negative Meniscus, convex to object | S-BSM18 (OHARA; modern equivalent of legacy 639/554 class) |
| L4 | Positive Meniscus, convex to object | S-TIH6 (OHARA; modern equivalent of legacy 805/254 class) |
| L5a | Biconvex Positive | S-LAL18 (OHARA; modern equivalent of legacy 729/547 class) |
| L5b | Biconcave Negative | S-TIH6 (OHARA; modern equivalent of legacy 805/254 class) |
| L6 | Positive Meniscus, concave to object | S-LAL14 (OHARA; modern equivalent of legacy 697/556 class) |
| L7 | Positive Meniscus, concave to object | S-LAL14 (OHARA; modern equivalent of legacy 697/556 class) |