US 2,645,975, sole example — Hiroshi Ito
| 6 ELEMENTS / 4 GROUPS |
| f ≈ 35.0 mm |
| F/3.2 (design F/3.0) |
| 2ω ≈ 64° |
| ALL SPHERICAL |
Unit focusing — entire optical assembly translates. The patent publishes no close state; the 1 m keyframe is a derived extension.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | SK5 (Schott) |
| L2 | Biconvex Positive | K-SK7 (SUMITA catalog equivalent; production supplier unspecified) |
| L3 | Biconcave Negative | FL4 (HOYA catalog equivalent; production supplier unspecified) |
| L4 | Biconcave Negative | FL4 (HOYA catalog equivalent; production supplier unspecified) |
| L5 | Biconvex Positive | BACD14 (HOYA catalog equivalent; production supplier unspecified) |
| L6 | Biconvex Positive | SK10 (Schott) |