DE 2 246 966 A1, Claim 3 — Georg Knetsch, Walter Watz
| 4 ELEMENTS / 4 GROUPS |
| f = 89.958 mm (modeled) |
| f/4 (stop-calibrated) |
| 2ω = 27° |
| ALL-SPHERICAL |
Not modeled — the patent supplies a static prescription, with no finite-focus spacings. Production minimum focus is 0.8 m.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | N-LAK21 (coordinate-compatible spectral proxy; supplier unconfirmed) |
| L2 | Positive Meniscus | N-LAK21 (coordinate-compatible spectral proxy; supplier unconfirmed) |
| L3 | Negative Meniscus | LAFN7 (coordinate-compatible spectral proxy; supplier unconfirmed) |
| L4 | Positive Meniscus | SF56A (coordinate-compatible spectral proxy; supplier unconfirmed) |