US 721,240 — Paul Rudolph
| 4 ELEMENTS / 3 GROUPS |
| f ≈ 144 mm (scaled from normalized patent) |
| F/5.5 |
| 2ω ≈ 60° |
| ALL SPHERICAL |
Inferred unit focus — all elements and the stop move objectward by 11.99 mm at the modeled 2 m object-to-image endpoint. No focus schedule is published; intermediate distance labels are approximate.
| Element | Type | Glass |
|---|---|---|
| L1 | Plano-Convex Positive | Unmatched patent medium (Abbe estimated; supplier unspecified) |
| L2 | Biconcave Negative | Unmatched patent medium (Abbe estimated; supplier unspecified) |
| L3 | Biconcave Negative | Unmatched patent medium (Abbe estimated; supplier unspecified) |
| L4 | Biconvex Positive | Unmatched patent medium (Abbe estimated; supplier unspecified) |