WO 2021/117563 A1 — Fumiaki Ohtake, Azuna Nonaka, Yoshiharu Yuasa, Takeshi Umeda
| 16 ELEMENTS / 11 GROUPS |
| f = 14.4–23.3 mm (patent) / 14–24 mm (production) |
| F/2.91 (constant) |
| 2ω = 115.2°–84.8° |
| 4 ASPHERICAL SURFACES (3 elements) |
| 4 ED ELEMENTS (S-FPL51) |
Inner focus — G2 cemented doublet (L21+L22) moves toward image. D8 increases, D11 decreases; Bf unchanged during focus. Minimal focusing mass for fast, silent STM AF.
| Element | Type | Glass |
|---|---|---|
| L11 | Neg. Meniscus (2× Asph) | S-BAL35 / L-BAL35 (OHARA) |
| L12 | Neg. Meniscus (1× Asph) | S-LAM60 (OHARA) |
| L13 | Biconcave Negative | S-FPL51 (OHARA) — ED fluorophosphate |
| L14 | Biconvex Positive | J-KZFH9 (HIKARI catalog equivalent; patent code 738323, vendor unspecified) |
| L21 | Negative Meniscus | TAFD40 (HOYA) — ultra-high-index dense flint |
| L22 | Positive Meniscus | S-TIM22 (OHARA) |
| L31 | Negative Meniscus | J-LASFH23 (Hikari) — dense flint (850270) |
| L32 | Positive Meniscus | S-FPM2 (OHARA) — fluorophosphate crown |
| L33 | Biconcave Negative | S-LAH98 (OHARA) |
| L34 | Biconvex Positive | S-TIH53 (OHARA) |
| L35 | Biconvex Positive | S-FPL51 (OHARA) — ED fluorophosphate |
| L36 | Negative Meniscus | S-LAH55 (OHARA) |
| L37 | Positive Meniscus | S-FPL51 (OHARA) — ED fluorophosphate |
| L38 | Biconvex Positive | S-FPL51 (OHARA) — ED fluorophosphate |
| L39 | Biconcave Negative | S-LAH55 (OHARA) |
| L40 | Pos. Meniscus (1× Asph) | S-LAH89 (OHARA) |