US 3,134,841 A, sole example — Helmut Knutti
| 5 ELEMENTS / 3 GROUPS |
| DESIGN f = 500.09 mm |
| DESIGN F/8 |
| ALL SPHERICAL |
The whole lens moves forward as a unit. The back gap grows from 171.36 mm at infinity to 206.21 mm at the maker's 8.5 m minimum distance, measured from object to image. This extension is derived: the patent prints no finite-distance state, and the factory focusing mechanism is not modelled. The infinity back focus is the Gaussian value; the patent prints 171.4 mm.
| Element | Type | Glass |
|---|---|---|
| LI | Biconvex Positive | BK1 (Schott legacy type; SUMITA catalog curve) |
| LII | Biconvex Positive | PC2 (Hoya equivalent) |
| LIII | Biconcave Negative | E-FD4 (Hoya equivalent) |
| LIV | Biconvex Positive | F2 (Schott equivalent) |
| LV | Biconcave Negative | S-BSM16 (Ohara equivalent) |