US 4,690,517 Table 1 — Fujie / Nippon Kogaku
| 20mm |
| f/2.8 |
| 94° FX |
| 12 elements / 9 groups |
| CRC floating focus |
CRC floating focus: the patent states that L1-L5 move as a unit to reduce d12 while the whole lens advances; close-focus numerical spacings are not published in US 4,690,517, so this file keeps the verified infinity prescription.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | S-BSM16 class (OHARA / 620603) |
| L2 | Negative Meniscus | SF56A equivalent (SCHOTT / 785261) |
| L3 | Negative Meniscus | S-LAL8 class (OHARA / 713539) |
| L4a | Biconvex Positive | S-TIH4 class (OHARA / 755275) |
| L4b | Biconcave Negative | S-LAH66 / TAF1 class (OHARA / HOYA / 773496) |
| L4c | Plano-Convex Positive | E-F1 equivalent (HOYA / 626357) |
| L5 | Biconvex Positive | S-TIM25 class (OHARA / 673322) |
| L6 | Positive Meniscus | J-BAF3 (HIKARI / Nikon) |
| L7a | Positive Meniscus | S-LAH66 / TAF1 class (OHARA / HOYA / 773496) |
| L7b | Biconcave Negative | SF56A equivalent (SCHOTT / 785261) |
| L8 | Positive Meniscus | S-BSM16 class (OHARA / 620603) |
| L9 | Biconvex Positive | S-BSM16 class (OHARA / 620603) |
Detailed analysis available in the interactive viewer above.