US 4,908,639 A — Masaaki Yanagisawa
| 7 ELEMENTS / 6 GROUPS |
| 135mm f/2 |
| 18° FULL FIELD |
| REAR FOCUS + DEFOCUS CONTROL |
| PATENT CLOSE STATE β = -0.0333 |
Published rear-focus anchors: corrected infinity to β = -0.0333 at 4.0967736 m object-to-image-plane. GR moves 6.8090 mm objectward while G1 and G2 remain fixed. The production 1.1 m minimum-focus endpoint is not reconstructed. DC motion changes D3 and compensates with GR motion while the inferred stop station remains fixed; the three close DC positions are patent-published.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconvex Positive | J-SK16 (HIKARI; coordinate-compatible current catalog match) |
| L2 | Biconcave Negative | S-TIM22 (OHARA special-order; code 648338 coordinate match) |
| L3 | Positive Meniscus | J-LAK8 (HIKARI; coordinate-compatible current catalog match) |
| L4 | Negative Meniscus | J-LAF7 (HIKARI; coordinate-compatible current catalog match) |
| L5 | Negative Meniscus | J-SF8 (HIKARI; coordinate-compatible current catalog match) |
| L6 | Positive Meniscus | J-LASFH2 (HIKARI; coordinate-compatible current catalog match) |
| L7 | Biconvex Positive | J-LASF017 (Hikari catalog equivalent to patent 797454; production supplier unspecified) |