| 摘要 |
A wide angle lens includes a first lens group having negative refractive power, as a whole, a second lens group having positive refractive power, as a whole, and a third lens group having positive refractive power, as a whole, in this order from an object side. The first lens group includes a positive meniscus lens with its convex surface facing the object side and three negative meniscus lenses, each with its convex surface facing the object side, in this order from the object side. The second lens group includes at least one cemented lens. The material of at least one of the three negative meniscus lenses in the first lens group satisfies the following conditional expression (1), and the material of at least one of the other negative meniscus lenses in the first lens group satisfies the following conditional expressions (2) and (3):;νda>81 (1);;νdb<25 (2); and;ΔθgFb>0.015 (3). |
| 主权项 |
1. A wide angle lens consisting of:
a first lens group having negative refractive power, as a whole; a second lens group having positive refractive power, as a whole; and a third lens group having positive refractive power, as a whole, in this order from an object side, wherein a stop is included between the second lens group and the third lens group; and wherein the first lens group consists of a positive meniscus lens with its convex surface facing the object side and three negative meniscus lenses, each with its convex surface facing the object side, in this order from the object side, and wherein the second lens group includes at least one cemented lens, and wherein the material of at least one of the three negative meniscus lenses in the first lens group satisfies the following conditional expression (1), and the material of at least one of the other negative meniscus lenses in the first lens group satisfies the following conditional expressions (2) and (3):
νda>81 (1);νdb<25 (2); andΔθgFb>0.015 (3), where νda: an Abbe number of the at least one of the three negative meniscus lenses with respect to d-line, νdb: an Abbe number of the at least one of the other negative meniscus lenses with respect to d-line, and ΔθgFb: anomalous dispersion characteristics of the at least one of the other negative meniscus lenses. |
