US 3,997,247 — Erhard Glatzel, Heinz Zajadatz
| 8 ELEMENTS / 5 GROUPS |
| f ≈ 40.0 mm |
| F/5.6 |
| 2ω ≈ 63° |
| ALL SPHERICAL |
No focusing mechanism or iris in the lens. US 3,997,247 publishes only the infinity state. The close state is a calculated whole-lens translation (+1.333 mm back focus) to the 1:30 reduction reported by third-party sources for its microfilm use; it is not a patent or manufacturer-published state.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | SF2 (Schott) |
| L2 | Negative Meniscus | KF3 class (Sumita; historical supplier unconfirmed) |
| L3a | Negative Meniscus | SF1 (Schott) |
| L3b | Biconvex Positive | N-LAK8 (Schott); LaK8-type lanthanum crown |
| L4a | Biconcave Negative | LLF7 class (Sumita; historical supplier unconfirmed) |
| L4b | Biconvex Positive | N-SSK8 (Schott); SSK8-type |
| L4c | Negative Meniscus | N-LAK8 (Schott); LaK8-type lanthanum crown |
| L5 | Negative Meniscus | FK3 (Schott, inquiry glass) |