US 5,000,550 Example 1 - Canon / Takahashi et al.
| 15 elements / 12 groups |
| 20.6-34.0 mm design zoom |
| f/2.8 |
| 2ω = 93°-65° patent field |
| 1 aspherical surface |
| Inner focus, first-group rear sub-group |
Inner focus: the rear sub-group of the negative first group moves toward the object, decreasing D4 and increasing D8.
| Element | Type | Glass |
|---|---|---|
| L1 | Negative Meniscus (1x Asph) | S-LAH66 class (OHARA) |
| L2 | Positive Meniscus | F3 / E-F3 class |
| L3 | Biconcave Negative | S-LAH58 / TAFD30 class |
| L4 | Biconvex Positive | SF57 / S-TIH53 class |
| L5 | Negative Meniscus | SF57 / S-TIH53 class |
| L6 | Biconvex Positive | N-LAK7 / S-LAL7 class |
| L7 | Positive Meniscus | N-LAK7 / S-LAL7 class |
| L8 | Biconcave Negative | S-LAH59 / TAF5 class |
| L9 | Biconcave Negative | S-LAL14 / N-LAK14 class |
| L10 | Biconvex Positive | SF6 / S-TIH6 class |
| L11 | Biconvex Positive | S-BSL7 (OHARA) / BK7-class crown |
| L12 | Negative Meniscus | N-SF14 / S-TIH14 class |
| L13 | Plano-Convex Positive | S-LAL14 / N-LAK14 class |
| L14 | Biconvex Positive | N-LAK7 / S-LAL7 class |
| L15 | Negative Meniscus | SF57 / S-TIH53 class |
Detailed analysis available in the interactive viewer above.