JP H01-193709 A — Hisashi Tokumaru, Shuji Ogino
| 13 ELEMENTS / 10 GROUPS |
| f ≈ 28.8–82.5 mm |
| F/3.6–4.63 |
| 2ω ≈ 73.8°–29.4° |
| ALL-SPHERICAL |
Reconstructed unit focusing of the front group L1; the patent publishes infinity states only. At each zoom station the L1 extension that brings a 0.8 m object-to-image subject onto the fixed image plane was solved (2.50 / 2.43 / 2.42 mm at 28.8 / 50 / 82.5 mm); only D8 changes. The 0.8 m minimum focus is from third-party sources, and the 1:4 macro mode is not modeled.
| Element | Type | Glass |
|---|---|---|
| E1 | Negative Meniscus | TAF1 (Hoya) / N-LAF34 class (772498 lanthanum flint; equivalent, Δνd −0.18) |
| E2 | Biconvex Positive | Unmatched (807316 lanthanum dense flint; coordinate of discontinued Schott LaSF8, not in the catalog; nearest current NBFD15 / H-ZLaF56B differ by Δνd ≈ +1.7) |
| E3 | Biconcave Negative | TAF1 (Hoya) / N-LAF34 class (772498 lanthanum flint; equivalent, Δνd −0.18) |
| E4 | Positive Meniscus | S-TIH53WN (OHARA) / FDS90 class (847239 dense flint; exact coordinate match) |
| E5 | Negative Meniscus | S-LAH60 (OHARA) (834371 lanthanum flint; close) |
| E6 | Biconvex Positive | H-LaK12 (CDGM) (697565 lanthanum crown; nd-exact, Δνd −0.33; equivalent) |
| E7 | Negative Meniscus | FF8 (Hoya) (750251 dense flint; close within the two-decimal nd) |
| E8 | Positive Meniscus | PCD4 (Hoya) / N-PSK53A class (618635 phosphate crown; close) |
| E9 | Positive Meniscus | S-TIH6 (OHARA) / SF6 class (805254 dense flint; exact) |
| E10 | Biconcave Negative | 743525 lanthanum crown (nearest S-LAL61 OHARA / TAC2 Hoya at Δnd −0.0015; not the same glass) |
| E11 | Biconvex Positive | N-LAK21 (Schott) (641601 lanthanum crown; exact) |
| E12 | Biconvex Positive | 670571 lanthanum crown (J-LAK02 Hikari class; nd printed to two decimals) |
| E13 | Negative Meniscus | NBFD9 (Hoya) class (757318 lanthanum flint; exact coordinate match, discontinued glass; equivalent) |