US 2,084,309 — Ludwig Bertele / Zeiss Ikon
| 7 elements / 4 groups |
| f = 35.0 mm |
| f/2.8 |
| 63.4° diagonal field |
| all-spherical |
Unit-focus rendering model. The patent gives only an infinity prescription; close focus uses a 1.0 m visualization assumption and varies only the back focus.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | Unmatched vintage Zeiss/Schott 672/472 (nd=1.6716, νd=47.2) |
| L2 | Positive Meniscus | Unmatched vintage Zeiss/Schott 672/472 (nd=1.6716, νd=47.2) |
| L3 | Plano-Convex | FK3 (Schott) |
| L4 | Plano-Concave | SF8 / N-SF8 equivalent (Schott) |
| L5 | Negative Meniscus | FK3 (Schott) |
| L6 | Biconvex Positive | Unmatched vintage Zeiss/Schott 672/472 (nd=1.6716, νd=47.2) |
| L7 | Negative Meniscus | Unmatched vintage Zeiss/Schott 533/489 (nd=1.5333, νd=48.9) |
Detailed analysis available in the interactive viewer above.