US 7,656,591 B2 EXAMPLE 1 — NIKON / H. YAMAMOTO
| 9 ELEMENTS / 8 GROUPS |
| f ≈ 41.2 mm (design) · 45 mm (marketed) |
| F/2.8 |
| 2ω ≈ 72° (design image circle) · 51° (FX format) |
| ALL SPHERICAL |
| 1 ED ELEMENT |
CRC floating focus: G1+G3 move as a linked unit; G2 moves at a different rate. ΔD1 = −ΔD2 ≈ 4.28 mm. Maximum reproduction ratio 1:2 (β = −0.50).
| Element | Type | Glass |
|---|---|---|
| L11 | Negative Meniscus | S-LAH55V (OHARA) |
| L12 | Biconvex Positive | Proprietary high-dispersion lanthanum flint (757/316) |
| L21 | Negative Meniscus | Nikon ED glass (near S-FPL51 / FCD1) |
| L22 | Biconvex Positive | N-LAF21 type (Schott) |
| L23 | Biconcave Negative | Proprietary flint (567/427) |
| L31 | Biconvex Positive | S-PHM52Q (OHARA) |
| L32 | Biconcave Negative | SF1 (Schott) / FD60 (HOYA) |
| L33 | Positive Meniscus | S-FSL5 (OHARA) / N-FK5 (Schott) |
| L34 | Biconvex Positive | S-LAH65V (OHARA) / TAF3 (HOYA) |
Detailed analysis available in the interactive viewer above.