DE 2359156 A1 Example 12 — Erhard Glatzel / Carl Zeiss
| 9 elements / 8 groups |
| f = 28.8 mm design |
| f/2 marketed; f/2.1 patent |
| 2ω = 74.5° |
| all-spherical |
Production Contax/Yashica literature identifies floating close-range correction, but DE 2359156 A1 Example 12 provides only the infinity-focus prescription; the model keeps the infinity BFD fixed.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | SK18A / N-SK18 class (Schott, 639554; patent νd retained) |
| L2 | Positive Meniscus | BASF2 / N-BASF2 class (Schott, 664358; patent νd retained) |
| L3 | Negative Meniscus | LAF2 / N-LAF2 class (Schott, 744448; patent values retained) |
| L4a | Biconvex Positive | LAF2 / N-LAF2 class (Schott, 744448; patent values retained) |
| L4b | Biconcave Negative | BAF4 / N-BAF4 class (Schott, 606439; patent values retained) |
| L4c | Biconvex Positive | LAK10 / N-LAK10 class (Schott, 720504; patent values retained) |
| L5 | Biconcave Negative | SF6 (Schott legacy, 805254) |
| L6 | Positive Meniscus | LAK8 / N-LAK8 class (Schott, 713538; patent values retained) |
| L7 | Positive Meniscus | LAF21 / N-LAF21 class (Schott, 788474; patent values retained) |
Detailed analysis available in the interactive viewer above.