US 2,681,594 Claim 3 — Hiroshi Ito / Canon Camera Co.
| 6 ELEMENTS / 4 GROUPS |
| f ≈ 50.0 mm |
| F/1.8 |
| 2ω ≈ 46° |
| ALL SPHERICAL |
Unit focusing — entire lens group moves axially.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | SK16 (Schott) |
| L2 | Biconvex Positive | Unmatched vintage barium dense flint (626391; not modern HOYA BAFD7 702412) |
| L3 | Biconcave Negative | S-TIH3 (OHARA) |
| L4 | Biconcave Negative | K10 (Schott) |
| L5 | Biconvex Positive | SK18 (Schott) |
| L6 | Biconvex Positive | SK18 (Schott) |
Detailed analysis available in the interactive viewer above.