US 1,998,704 EXAMPLE I — BERTELE / ZEISS IKON (1932) — SCALED 0.5× TO 50mm
| 6 ELEMENTS / 3 GROUPS |
| f ≈ 50.0 mm (scaled from 100mm patent) |
| F/2.0 |
| 2ω ≈ 46.8° |
| ALL SPHERICAL |
Unit focus — entire optical assembly translates via Contax body helicoid. No internal moving groups.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | SK16 (Schott dense crown) |
| L2 | Positive Meniscus | BaLF5 (Schott barium light flint) |
| L3 | Biconvex Positive | FK3 (Schott fluorite crown) |
| L4 | Biconcave Negative | SF-type (Schott dense flint) |
| L5 | Negative Meniscus | BaK4 (Schott barium crown) |
| L6 | Biconvex Positive | BaLF5 (Schott barium light flint) |
Detailed analysis available in the interactive viewer above.