US 2019/0041605 A1 — Shinichiro Saito, Makoto Nakahara
| 16 active elements / 12 groups (rear filter omitted) |
| Patent f = 392.00 mm; traced EFL = 391.938 mm |
| Design F/2.90; 2ω = 6.32° |
| Imageward L2 inner focus; transverse L3B image-stabilization group |
CONSTRAINED_RECONSTRUCTION: the patent publishes L2 axial focusing with L3 fixed but no finite-focus spacing table. The close endpoint is a one-DOF code solve to Canon's rounded 2.5 m MFD: L2 shifts +19.0782676028358 mm imageward while the adjacent gaps preserve 41.49 mm exactly. The model predicts |m| = 0.176031 at 2.5 m; Canon's rounded 0.17× value reverses to about 2.5795 m in this patent prescription.
| Element | Type | Glass |
|---|---|---|
| L1-1 | Positive Meniscus | 595677 class; optical proxy S-FPM2 (OHARA) |
| L1-2 | Biconvex Positive | 437951 ultra-low-dispersion class; spectral proxy FCD100 (HOYA) |
| L1-3 | Biconcave Negative | 806333 dense-flint class; spectral proxy NBFD15 (HOYA) |
| L1-4 | Plano-Convex Positive | 437951 ultra-low-dispersion class; spectral proxy FCD100 (HOYA) |
| L1-5 | Positive Meniscus | S-NPH4 catalog equivalent (OHARA; production supplier unspecified) |
| L1-6 | Negative Meniscus | S-LAH60 catalog equivalent (OHARA; production supplier unspecified) |
| L1-7 | Positive Meniscus | 437951 ultra-low-dispersion class; spectral proxy FCD100 (HOYA) |
| L2-1 | Biconcave Negative | 618634 phosphate-crown class; spectral proxy PCD4 (HOYA) |
| L3A-1 | Negative Meniscus | S-NPH4 catalog equivalent (OHARA; production supplier unspecified) |
| L3A-2 | Biconvex Positive | S-NSL36 catalog equivalent (OHARA; production supplier unspecified) |
| L3B-1 | Biconvex Positive | 806333 dense-flint class; spectral proxy NBFD15 (HOYA) |
| L3B-2 | Biconcave Negative | S-FPM3 catalog equivalent (OHARA; production supplier unspecified) |
| L3B-3 | Biconcave Negative | S-LAL18 legacy catalog equivalent (OHARA; production supplier unspecified) |
| L3C-1 | Biconvex Positive | S-NBH5 catalog equivalent (OHARA; production supplier unspecified) |
| L3C-2 | Biconvex Positive | S-NBH8 catalog equivalent (OHARA; production supplier unspecified) |
| L3C-3 | Negative Meniscus | S-NPH1 catalog equivalent (OHARA; production supplier unspecified) |