| 摘要 |
An imaging lens includes: a first lens group; a stop; a positive second lens group; and a negative third lens group which is fixed while focusing, in order from the object side. The first lens group includes at least one positive lens, at least one cemented lens, and a negative meniscus lens having a concave surface toward the image side, in order from the object side. The second lens group includes a cemented lens formed by a biconcave lens and a biconvex lens and a biconvex lens, in order from the object side. The third lens group includes a negative meniscus lens having a convex surface toward the object side, a biconcave lens, and a biconvex lens, in order from the object side. The first lens group, the stop, and the second lens group move integrally along the optical axis to focus from an infinite to a finite distance. |
| 主权项 |
1. An imaging lens consisting of in order from an object side to an image side:
a first lens group; a stop; a second lens group having a positive refractive power; and a third lens group having a negative refractive power which is fixed during focusing operations, the first lens group consisting of, in order from the object side to the image side, at least one lens having a positive refractive power, at least one cemented lens, and a negative meniscus lens having a concave surface toward the image side, the second lens group consisting of, in order from the object side to the image side, a cemented lens formed by a biconcave lens and a biconvex lens, and a biconvex lens, the third lens group consisting of, in order from the object side to the image side, a negative meniscus lens having a convex surface toward the object side, a biconcave lens, and a biconvex lens, the first lens group, the stop, and the second lens group being moved integrally along an optical axis to perform focusing from an infinite distance to a finite distance. |
