US 4,717,245, Example 2 — Sadatoshi Takahashi
| 11 ELEMENTS / 9 GROUPS |
| f ≈ 50.0 mm |
| F/1.0 |
| 2ω ≈ 45.2° |
| 2 ASPHERICAL SURFACES |
Unit extension of the whole optical block (the patent's preferred method); the close-focus back gap is calculated for the 0.6 m production MFD. The production lens uses a floating system whose group displacements are not published.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | BACD14 (HOYA catalog equivalent) |
| L2 | Positive Meniscus | S-LAL14 (OHARA catalog equivalent) |
| L3 | Neg. Meniscus (1× Asph) | S-NSL36 (OHARA catalog equivalent) |
| L4 | Positive Meniscus | S-LAH58 (OHARA catalog equivalent) |
| L5 | Negative Meniscus | S-NSL36 (OHARA catalog equivalent) |
| L6 | Biconcave Negative | PBH53 (OHARA catalog equivalent) |
| L7 | Biconvex Positive | S-LAH58 (OHARA catalog equivalent) |
| L8 | Neg. Meniscus (1× Asph) | S-TIH6 (OHARA catalog equivalent) |
| L9 | Positive Meniscus | S-LAH58 (OHARA catalog equivalent) |
| L10 | Biconvex Positive | S-LAH58 (OHARA catalog equivalent) |
| L11 | Positive Meniscus | S-BAL50 (OHARA catalog equivalent; production supplier unspecified) |