US 4,289,385 Example 1 — Asahi Kogaku / Yamagata
| 5 ELEMENTS / 5 GROUPS |
| f ≈ 50.0 mm |
| F/2.8 |
| 2ω ≈ 24° |
| ALL SPHERICAL |
Unit focus — entire lens assembly translates forward via helicoid barrel. MFD 0.9 m.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | S-BSM14 (OHARA) |
| L2 | Positive Meniscus | S-BSL7 (OHARA) |
| L3 | Near Plano-Concave Negative | S-TIH6 (OHARA) |
| L4 | Positive Meniscus | S-TIH13 (OHARA) |
| L5 | Positive Meniscus | J-BASF2 (Hikari) |
Detailed analysis available in the interactive viewer above.