US 2,838,978 — Jiro Mukai
| 4 ELEMENTS / 3 GROUPS |
| EFL 50.0499 mm |
| F/2.8 |
| FULL FIELD 46° |
| ALL SPHERICAL |
Conditional rigid-cell paraxial model to Canon's published 1.0 m closest focus; production mechanism not stated in the patent.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | K-LaK11 (Sumita; 658573 exact coordinate equivalent, original Canon melt not identified) |
| L2 | Biconcave Negative | S-FTM16 catalog equivalent (patent 593343; production supplier unspecified) |
| L3 | Plano-Concave Negative | NSL7 (OHARA; 511605 close coordinate equivalent to patent 511606, original Canon melt not identified) |
| L4 | Biconvex Positive | K-LaK9 (Sumita; 691548 exact coordinate equivalent, original Canon melt not identified) |