US 3,524,697 Example 1 — Isshiki / Matsuki
| 9 elements / 6 groups |
| f ≈ 6.00 mm |
| F/5.6 |
| 2ω = 220° |
| all-spherical |
Fixed-focus mirror-lock-up fisheye; the patent publishes no variable air spacings.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | BACD4 / N-SK4 class (613/586) |
| L2 | Negative Meniscus | BACD16 / N-SK16 / S-BSM16 class (620/603) |
| L3 | Biconcave Negative | FC5 / N-FK5 / S-FSL5 class (488/703) |
| L4 | Positive Meniscus | FD110 / N-SF11 / S-TIH11 class (785/260) |
| L6 | Biconcave Negative | FD110 / N-SF11 / S-TIH11 class (785/260) |
| L7 | Biconvex Positive | LAF2 / N-LAF2 / S-LAM2 class (744/450) |
| L8 | Positive Meniscus | 768465 — lanthanum flint patent melt (nd=1.76764, νd=46.5; no exact public catalog match) |
| L9 | Negative Meniscus | FD110 / N-SF11 / S-TIH11 class (785/260) |
| L10 | Biconvex Positive | S-BSM22 (OHARA) / N-SSK2 class (622/532) |
Detailed analysis available in the interactive viewer above.