US 5,949,588 — Kouichi Ohshita, Atsushi Shibayama
| 3 elements / 2 groups |
| f = 20.0 mm (scaled from patent f = 100) |
| f/8 marketed; f/8.25 design |
| 2ω = 164.0° patent field |
| all-spherical |
Fixed-focus production lens. The patent notes optional whole-lens extension or L1-only focusing, but Table 8 provides no close-focus spacing data.
| Element | Type | Glass |
|---|---|---|
| L1 | Plano-Concave Negative | N-SK16 / S-BSM16 class (620/601; patent νd=60.14) |
| L2 | Thick Negative Meniscus | N-SF6 / S-TIH6 class (805/254) |
| L3 | Biconvex Positive | S-LAL52 catalog equivalent (patent 670575; production supplier unspecified) |