JP 2025-50505 A — Takeharu Nakada
| 10 ELEMENTS / 9 GROUPS |
| f ≈ 14.41–29.35 mm |
| F/4.08–6.43 |
| 2ω ≈ 80.7°–51.4° (PARAXIAL) |
| 4 ASPHERICAL SURFACES (2 MOLDED-POLYMER ELEMENTS) |
| 1 UD-CLASS ELEMENT |
Inner focus: the two-element group L3 (G31 + G32) moves toward the image for close focus while L1, L2, L4 and the image plane stay fixed (patent [0036]). Close-focus spacings are a constrained reconstruction, not patent data: the L3 shift at each zoom station is solved for Canon's 0.15 m object-to-image minimum distance (paraxial magnification ≈ −0.18 / −0.25 / −0.38 at W / M / T); intermediate focus positions use linear gap interpolation.
| Element | Type | Glass |
|---|---|---|
| G11 | Negative Meniscus | S-LAH66 / TAF1 class (772496 lanthanum flint; vendor unresolved) |
| G12 | Biconcave Negative (2× Asph) | Unmatched (molded optical polymer, COP-like coordinates nd 1.53504 / νd 55.7; supplier and grade unconfirmed) |
| G13 | Biconvex Positive | S-TIH53WN class (supplier-neutral spectral proxy) |
| G21 | Positive Meniscus | S-FSL5 class (supplier-neutral spectral proxy) |
| G22 | Positive Meniscus | S-LAH65VS class (supplier-neutral spectral proxy) |
| G23 | Negative Meniscus | S-LAH98 / TAFD45 class (954323 dense lanthanum flint; vendor unresolved) |
| G24 | Biconvex Positive | S-FPL51 / FCD1 class (497816 fluorophosphate ED crown; inferred UD assignment; supplier unconfirmed) |
| G31 | Biconcave Negative | S-TIM27 class (supplier-neutral spectral proxy) |
| G32 | Pos. Meniscus (2× Asph) | Unmatched (molded optical polymer, COP-like coordinates nd 1.53504 / νd 55.7; supplier and grade unconfirmed) |
| G41 | Positive Meniscus | TAFD37A class (supplier-neutral spectral proxy) |