US 2,995,980 — Otto Zimmermann, Georg Knetsch
| 5 ELEMENTS / 3 GROUPS |
| f ≈ 90.1 mm |
| F/2.8 |
| 2ω ≈ 27.0° |
| ALL SPHERICAL |
Unit focusing — entire optical assembly translates forward via helicoid. Detachable head for Visoflex use.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconvex Positive | K-LaK9 catalog equivalent (patent coordinate; production supplier unspecified) |
| L2 | Positive Meniscus | SF4 catalog equivalent (patent coordinate; production supplier unspecified) |
| L3 | Biconcave Negative | E-FD7 catalog equivalent (exact patent code 640346; production supplier unspecified) |
| L4 | Biconcave Negative | F1 catalog equivalent (exact patent coordinate; production supplier unspecified) |
| L5 | Biconvex Positive | N-LAF2 catalog equivalent (historical LaF 2 family; production supplier unspecified) |