US 4,154,509, sole example — Yasuo Takahashi
| 5 ELEMENTS / 4 GROUPS |
| DESIGN f = 40 mm |
| DESIGN F/2.8 |
| ALL SPHERICAL |
| PATENT f = 100 SCALED × 0.4 |
The patent names no focusing group or motion and prints the infinity state only, so the lens is modeled at infinity with no focus movement; 0.6 m is the retail minimum focus.
| Element | Type | Glass |
|---|---|---|
| L1 | Biconvex Positive | TAFD30 (HOYA catalog equivalent; production supplier unspecified) |
| L2 | Biconcave Negative | PBM28 (OHARA catalog equivalent; production supplier unspecified) |
| L3 | Biconcave Negative | SF15 (SUMITA catalog equivalent; production supplier unspecified) |
| L4 | Biconvex Positive | TAF5 (HOYA coordinate equivalent; patent νd 46.8 versus catalog 46.6) |
| L5 | Positive Meniscus | S-LAH65 (OHARA catalog equivalent; production supplier unspecified) |