US 3,838,911, Embodiment 2 — Yoshitsugi Ikeda
| 5 ELEMENTS / 4 GROUPS |
| DESIGN f = 200 mm |
| DESIGN F/4 |
| ALL SPHERICAL |
Unit focus: the whole five-element block moves forward on a straight helicoid. The patent prints the infinity state only; the 2.5 m close state (back focus 83.56 mm, about 1:10.2) is derived paraxially for the retail 2.5 m object-to-image distance and is not a published spacing.
| Element | Type | Glass |
|---|---|---|
| L1 | Plano-Convex Positive | S-BSM16 (OHARA catalog equivalent; production supplier unspecified) |
| L2 | Biconvex Positive | S-FSL5 (OHARA catalog equivalent; production supplier unspecified) |
| L3 | Biconcave Negative | S-TIH14 (OHARA catalog equivalent; production supplier unspecified) |
| L4 | Negative Meniscus | S-LAL12 (OHARA catalog equivalent; production supplier unspecified) |
| L5 | Positive Meniscus | S-TIH11 (OHARA catalog equivalent; production supplier unspecified) |