US 4,621,909 Example 3 — Hamanishi / Nippon Kogaku
| 7 elements / 6 groups |
| f = 51.6 mm design / 50 mm nominal |
| F1.2 |
| 2ω = 46.4° patent / 46° Nikon spec |
| All-spherical modified Gauss |
Patent three-unit floating short-distance correction; variable-gap endpoint is d0 = 514.966 mm from the first surface and m ≈ -0.10. Production AI-S specification is 0.5 m and 1:7.9.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | Unmatched Nikon/Hikari lanthanum glass (797/455; J-LASF017 / TAF2 class) |
| L2 | Positive Meniscus | Unmatched lanthanum dense flint (796/410; closest J-LASF02 / S-LAH52 class) |
| L3 | Negative Meniscus | J-SF1 / E-FD1L class (717/295) |
| L4 | Negative Lens | J-SF4 / N-SF4 class (755/276) |
| L5 | Positive Lens | J-LASF016 / TAF1 class (773/494 patent; catalog class 773/496) |
| L6 | Positive Meniscus | J-LASF016 / TAF1 class (773/494 patent; catalog class 773/496) |
| L7 | Biconvex Positive | S-LAM60 / J-LAF010 / NBF1 class (744/495 patent; catalog class 743/493) |
Detailed analysis available in the interactive viewer above.