US 2021/0263286 A1 — Junya Ichimura
| 6 ELEMENTS / 5 GROUPS |
| 50mm f/1.8 (MARKETED) |
| f = 49.5616 mm / F1.8527 (MODELED) |
| 2ω = 47.16° (PATENT) / 46° (MARKETED) |
| 1 ASPHERICAL ELEMENT / 2 ASPHERICAL SURFACES |
CONSTRAINED_RECONSTRUCTION — patent ¶0048 specifies rigid unit focus (LF + STO + LR translate together). The 0.30 m close state is code-solved from Canon's MFD, normalized to object-to-image-plane distance: S12→IMG = 38.059827 mm, 12.392715 mm outward travel from computed infinity, with paraxial magnification -0.250047×. The reference-plane normalization is a modeling choice; all internal spacings remain fixed, and no finite-distance spacing row is published in the patent.
| Element | Type | Glass |
|---|---|---|
| L11 | Positive Meniscus | 835427 class (vendor unresolved) |
| L12 | Positive Meniscus | 800422 class (vendor unresolved) |
| L13 | Negative Meniscus | 805254 class (vendor unresolved) |
| L21 | Negative Meniscus | 673321 class (vendor unresolved) |
| L22 | Pos. Meniscus (2× Asph) | Unmatched (resin material; patent nd=1.53110, vd=55.9) |
| L23 | Biconvex Positive | 734515 class (vendor unresolved) |