| 摘要 |
A zoom lens consists of, in order from the object side, a positive first lens group that is fixed during magnification change, at least two movable lens groups that are moved during magnification change, and a positive end lens group that is disposed at the most image side and is fixed during magnification change. The first lens group consists of, in order from the object side, a negative first-a lens group that is fixed during focusing, a positive first-b lens group that is moved during focusing, and a positive first-c lens group. The first-a lens group includes at least two negative lenses, where the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first-a lens group, satisfies given condition expressions (1) to (3). |
| 主权项 |
1. A zoom lens consists of, in order from the object side, a first lens group that has a positive refractive power and is fixed during magnification change, at least two movable lens groups that are moved during magnification change with changing the distances along the optical axis direction between adjacent lens groups, and an end lens group that has a positive refractive power, is disposed at the most image side, and is fixed during magnification change,
wherein the first lens group consists of, in order from the object side, a first-a lens group that has a negative refractive power and is fixed during focusing, a first-b lens group that has a positive refractive power and is moved during focusing with changing the distances along the optical axis direction between adjacent lens groups, and a first-c lens group that has a positive refractive power, the first-a lens group includes at least two negative lenses, wherein the most object-side negative lens has a meniscus shape with the convex surface toward the object side, and a first-n lens, which is at least one negative lens of the rest of the negative lenses of the first-a lens group, satisfies the condition expressions (1), (2), and (3) below:
62<vdn (1),0.64<θgFn+0.001625×vdn<0.7 (2), and1<fln/fla<2 (3), where vdn is an Abbe number with respect to the d-line of the first-n lens, θgFn is a partial dispersion ratio of the first-n lens, fln is a focal length with respect to the d-line of the first-n lens, and fla is a focal length with respect to the d-line of the first-a lens group. |
