US 3,868,174 A, Example 1 — Hideo Yokota
| 5 ELEMENTS / 4 GROUPS (PATENT; CANON LISTS 6/5) |
| DESIGN f = 100 (SCALED ×3) |
| DESIGN F/2.8 |
| ALL SPHERICAL |
| FLUORITE FRONT ELEMENT |
Patent infinity state only; the production lens focuses to 3.5 m. The patent prints no close-focus spacing.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconvex Positive (Fluorspar) | CaF2 (fluorspar, named in claim 1; catalog dispersion curve, patent nd and νd kept) |
| L2 | Biconcave Negative | S-LAH51 (OHARA catalog equivalent; production supplier unspecified) |
| L3 | Biconvex Positive | S-FSL5 (OHARA catalog equivalent; production supplier unspecified) |
| L4 | Negative Meniscus | K-BK7 (SUMITA catalog equivalent; production supplier unspecified) |
| L5 | Positive Meniscus | S-TIH18 (OHARA catalog equivalent; production supplier unspecified) |