US 4,046,459 Example 2 — Canon / Kawamura
| 7 elements / 7 groups |
| 28 mm |
| F/2.8 |
| 75° diagonal AoV |
| All-spherical retrofocus |
Unit focus modeled as whole-cell extension; only the final back-focus gap varies.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | SK8/BACD8 class (legacy 611/559 dense barium crown) |
| L2 | Negative Meniscus | BaF5 class (legacy 607/493 barium flint/crown-boundary glass) |
| L3 | Positive Meniscus | S-BAH28 (OHARA) / BAFD8 (HOYA) equivalent |
| L4 | Biconvex Positive | S-BSM14 (OHARA) / BACD14 (HOYA) / N-SK14 equivalent |
| L5 | Biconcave Negative | S-TIH13 (OHARA) / E-FD13 (HOYA) equivalent |
| L6 | Positive Meniscus | S-LAL13 / LAC13 class (694/533 lanthanum crown equivalent) |
| L7 | Positive Meniscus | S-LAL13 / LAC13 class (694/533 lanthanum crown equivalent) |
Detailed analysis available in the interactive viewer above.