US 3,748,021 Example 2 — Canon Floating System retrofocus wide-angle
| 24mm f/2.8 |
| 9 elements / 8 groups |
| 84° diagonal field |
| Floating front-group air space |
| Canon FD mount |
Whole-lens focusing with Canon Floating System correction: D4 closes as the lens advances; BF is solved to Canon's 0.3 m MFD.
| Element | Type | Glass |
|---|---|---|
| E1 | Negative Meniscus | S-BAL35 (OHARA; SK5-class equivalent) |
| E2 | Positive Meniscus | S-BAL35 (OHARA; SK5-class equivalent) |
| E3 | Negative Meniscus | N-BALF4 (SCHOTT; BaLF4-class equivalent) |
| E4 | Biconvex Positive | S-TIH6 (OHARA; SF6-class equivalent) |
| E5 | Biconvex Positive | S-BAL35 (OHARA; SK5-class equivalent) |
| E6 | Biconcave Negative | S-TIH6 (OHARA; SF6-class equivalent) |
| E7 | Negative Meniscus | S-BAH28 (OHARA; BaSF-class equivalent) |
| E8 | Positive Meniscus | S-LAL8 (OHARA; LaK8-class equivalent) |
| E9 | Positive Meniscus | S-LAL8 (OHARA; LaK8-class equivalent) |
Detailed analysis available in the interactive viewer above.