US 4,728,179 — Hikaru Hayashi, Hiroshi Takase
| 6 ELEMENTS / 4 GROUPS |
| DESIGN f = 51.84 mm |
| DESIGN F/1.86 |
| ALL SPHERICAL |
Unit focus: the whole lens moves forward 7.74 mm, the back focus growing from 37.856 mm at infinity to 45.60 mm at the marketed 0.45 m minimum, object to image. The patent prints no focus travel; the near gap is solved paraxially, and its 0.149× magnification matches the published 16 × 24 cm minimum field.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | S-TIH11 (OHARA catalog equivalent; production supplier unspecified) |
| L2 | Positive Meniscus | BACD14 (HOYA, coordinate equivalent) |
| L3 | Negative Meniscus | S-TIH11 (OHARA catalog equivalent; production supplier unspecified) |
| L4 | Negative Meniscus | S-TIH10 (OHARA catalog equivalent; production supplier unspecified) |
| L5 | Positive Meniscus | LAH53 (OHARA catalog equivalent; production supplier unspecified) |
| L6 | Biconvex Positive | LAH53 (OHARA catalog equivalent; production supplier unspecified) |