US 5,528,428 — Motoyuki Ohtake, Motohisa Mouri
| 7 ELEMENTS / 5 GROUPS |
| f ≈ 28.9 mm |
| F/2.87 |
| 2ω ≈ 74.0° |
| ALL SPHERICAL |
Unit focus — entire lens assembly moves axially.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus | S-TIL6 (OHARA) |
| L2a | Biconvex Positive | 840433 - lanthanum flint (patent nd=1.84042, vd=43.30; no exact public catalog match) |
| L2b | Biconcave Negative | E-FD2 (HOYA) |
| L3a | Biconvex Positive | S-LAH59 (OHARA) |
| L3b | Biconcave Negative | EF3 (HOYA) |
| L4 | Positive Meniscus | J-LASF017 (Hikari catalog-equivalent to patent 797454; supplier not identified) |
| L5 | Negative Meniscus | 595/355 (close to S-FTM16, OHARA) |