US 5,267,086 — Hiroyuki Hirano
| 5 ELEMENTS / 4 GROUPS |
| f ≈ 85.0 mm |
| F/2.8 |
| 2ω ≈ 28.4° |
| ALL SPHERICAL |
Front-group unit focus: L1–L4 translate forward as a rigid unit, L5 remains fixed relative to the film plane. AF via Pentax K-mount in-body motor.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | N-SSK5 (Schott; exact 658509 coordinate match) |
| L2 | Negative Meniscus | FD110 (HOYA) / S-TIH11 equivalent (785257) |
| L3 | Negative Meniscus | S-TIH10 (OHARA; exact 728285 coordinate match) |
| L4 | Biconvex Positive | S-LAH63 (OHARA) |
| L5 | Negative Meniscus | BSC7 (HOYA) |