US 4,258,985 — Akiyoshi Nakamura
| 9 elements / 9 groups |
| f = 28.0 mm |
| F2.0 |
| 2ω = 75° |
| all-spherical |
Single patent configuration; close focus is represented by unit-extension BFD change to the 0.3 m production MFD.
| Element | Type | Glass |
|---|---|---|
| L1 | Weak Biconvex Positive | H-LaK6A (CDGM catalog equivalent; patent code 694536, supplier unspecified) |
| L2 | Negative Meniscus | NSL7 (OHARA legacy catalog equivalent; patent code 511605, supplier unspecified) |
| L3 | Negative Meniscus | NSL7 (OHARA legacy catalog equivalent; patent code 511605, supplier unspecified) |
| L4a | Positive Meniscus | NBFD5 (Hoya catalog equivalent; patent code 762404, supplier unspecified) |
| L4b | Weak Biconvex Positive | NBFD5 (Hoya catalog equivalent; patent code 762404, supplier unspecified) |
| L5 | Positive Meniscus | 750504 - dense lanthanum crown class (catalog unresolved) |
| L6 | Biconcave Negative | S-TIH6 (OHARA catalog equivalent; patent code 805252, supplier unspecified) |
| L7 | Positive Meniscus | 773501 - lanthanum flint (catalog unresolved) |
| L8 | Weak Biconvex Positive | K-LaK14 (SUMITA catalog equivalent; patent code 697558, supplier unspecified) |