US 4,063,802 EMBODIMENT 1 — OLYMPUS / IMAI & IKEDA
| 5 ELEMENTS / 4 GROUPS |
| f ≈ 85.0 mm |
| F/2 |
| 2ω ≈ 29° |
| ALL SPHERICAL |
Floating rear group: entire lens extends via helicoid (unit focus) while the cemented doublet (L4+L5) moves at a slightly different rate via an internal cam, changing d₆ to correct astigmatism and coma at close distances.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | LaK family (720/503) |
| L2 | Positive Meniscus | SK/PSK family (623/581) |
| L3 | Negative Meniscus | HOYA FD110 (exact match, SF family, 785/257) |
| L4 | Biconvex Positive | LaK family (700/481) |
| L5 | Negative Meniscus | OHARA S-BAL42 (near-exact, BaK family, 583/594) |
Detailed analysis available in the interactive viewer above.