US 2,721,499 EXAMPLE 2 — BERTELE / CARL ZEISS
| 8 ELEMENTS / 5 GROUPS |
| f ≈ 19.0 mm (design) |
| F/4.5 |
| 2ω ≈ 91.7° |
| ALL SPHERICAL |
Unit focus — entire lens translates axially.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | BK crown (504/667) |
| L2 | Negative Meniscus | FK5 fluorite crown (487/703) |
| L3 | Negative Meniscus | LaK10 lanthanum crown (721/503) |
| L4 | Biconvex Positive | SK7 dense crown (607/595) |
| L5 | Biconcave Negative | BaK/SK crown (561/575) |
| L6 | Biconvex Positive | SK-type dense crown (625/533) |
| L7 | Negative Meniscus | SF1 dense flint (720/293) |
| L8 | Negative Meniscus | LaK/SK crown (642/581) |
Detailed analysis available in the interactive viewer above.