GB 978,797, Example 1 — Wolf Dannberg, Eberhard Dietzsch
| 10 ELEMENTS / 6 GROUPS |
| f = 20.002 mm |
| F/4 |
| 2ω ≈ 93° |
| ALL SPHERICAL |
Infinity prescription only; the patent gives no focus travel. The production lens focuses to 0.16 m.
| Element | Type | Glass |
|---|---|---|
| L1 | Positive Meniscus | S-LAL13 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L2 | Negative Meniscus | S-LAL13 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L3 | Negative Meniscus | S-LAL13 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L4 | Negative Meniscus | N-SK16 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L5 | Plano-Convex Positive | J-LLF1 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L6 | Negative Meniscus | Unmatched (728380; nearest current dense-barium-flint family outside Δn=0.003) |
| L7 | Biconvex Positive | S-TIM3 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L8 | Biconcave Negative | Unmatched (678322; nearest SF5/ZF2 coordinate family outside Δn=0.003) |
| L9 | Positive Meniscus | C2 (coordinate-compatible dispersion proxy; historical supplier unconfirmed) |
| L10 | Biconvex Positive | LACL9 (HOYA) class (678508 lanthanum crown, LaLK9 type; Δnd −0.0001, Δνd −0.25; discontinued-glass equivalent) |