US 4,223,981 — Norio Mizutani, Yoshinari Hamanishi
| 12 ELEMENTS / 9 GROUPS |
| COMPUTED EFL 80.102-199.912 mm |
| F/4.5 |
| ALL-SPHERICAL |
| FRONT-GROUP FOCUS |
CONSTRAINED_RECONSTRUCTION: front Group 1 focusing. D5 close-focus values were code-solved at 1.8 m from the focal plane while the relay and image plane remain fixed; the patent publishes no finite-focus cam table.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconvex Positive | 564608 — dense barium crown class (catalog vendor unspecified) |
| L2a | Biconvex Positive | 603607 — dense crown class (catalog vendor unspecified) |
| L2b | Negative Meniscus | 805255 — dense flint class (catalog vendor unspecified) |
| L3a | Positive Meniscus | 755275 — dense flint class (catalog vendor unspecified) |
| L3b | Biconcave Negative | 517642 — borosilicate crown class (catalog vendor unspecified) |
| L4 | Biconcave Negative | 589612 — dense barium crown class (catalog vendor unspecified) |
| L5a | Biconvex Positive | 620603 — dense crown class (catalog vendor unspecified) |
| L5b | Negative Meniscus | 755275 — dense flint class (catalog vendor unspecified) |
| L6 | Positive Meniscus | 517642 — borosilicate crown class (catalog vendor unspecified) |
| L7 | Negative Meniscus | E-LAF11 (HIKARI; historical 757316 match to patent 757317 class) |
| L8 | Negative Meniscus | J-LAK8 (HIKARI; 713540 match to patent 713539 class) |
| L9 | Biconvex Positive | 518590 — crown class (catalog vendor unspecified) |