US 4,364,644 EXAMPLE 1 — IKEMORI / CANON K.K.
| 8 ELEMENTS / 6 GROUPS |
| f ≈ 50.0 mm |
| F/1.2 |
| 2ω = 46° |
| 1 ASPHERICAL SURFACE |
Split-unit focus: L1–L7 extend forward as a rigid assembly; L8 remains fixed relative to the camera mount. Only gap D12 (between R12 and R13) changes, increasing from 0.194 mm at infinity to ≈ 6.38 mm at MFD = 0.6 m.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | OHARA S-LAH58 (804466) |
| L2 | Positive Meniscus (1× Asph) | OHARA S-LAH52 (744447) |
| L3 | Negative Meniscus | OHARA S-TIM27 (636354) |
| L4 | Biconcave Negative | S-TIH6 / Schott SF6 (805254) |
| L5 | Biconvex Positive | OHARA S-LAH59 (816466) |
| L6 | Positive Meniscus | OHARA S-LAH64 (883408) |
| L7 | Biconvex Positive | OHARA S-LAL18 (773496) |
| L8 | Biconvex Positive | OHARA S-BAL35* (623582; provisional, Δν_d=−1.12) |
Detailed analysis available in the interactive viewer above.