JP S40-028384 B, Example 1 — Tomokazu Kazamaki, Yasuo Takahashi
| 8 ELEMENTS / 6 GROUPS |
| DESIGN f = 50 mm |
| DESIGN F/1.4 |
| ALL SPHERICAL |
Unit focus: the whole optical unit moves forward on the helicoid, so only the back focus changes. The patent publishes the infinity state alone. The 0.45 m close state (object to image, the maker's minimum focus distance) is derived paraxially and is not a patent state: back focus 37.71 to 44.847 mm (7.14 mm extension), magnification -0.143x.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | NBFD13 (HOYA catalog equivalent; production supplier unspecified) |
| L2 | Positive Meniscus | NBFD13 (HOYA catalog equivalent; production supplier unspecified) |
| L3 | Negative Meniscus | E-FD13 (HOYA catalog equivalent; production supplier unspecified) |
| L4 | Biconcave Negative | E-FD13 (HOYA catalog equivalent; production supplier unspecified) |
| L5 | Biconvex Positive | NBFD11 (HOYA catalog equivalent; production supplier unspecified) |
| L6 | Negative Meniscus | BAFD7 (HOYA catalog equivalent; production supplier unspecified) |
| L7 | Positive Meniscus | NBFD11 (HOYA catalog equivalent; production supplier unspecified) |
| L8 | Biconvex Positive | NBFD11 (HOYA catalog equivalent; production supplier unspecified) |