Zoom lens and imaging device

Abstract

To provide a compact, light-weight zoom lens which offers high optical performance that is also suitable for video shooting, and an image capturing device equipped with the same.SOLUTION: A zoom lens disclosed herein comprises a first lens group having negative refractive power and a second lens group comprising one or more lens groups and having positive refractive power as a whole, arranged in order from the object side to the image plane side. One of the first and second lens groups has a focusing group. When zooming and focusing, air gaps between pairs of adjacent lens groups or adjacent lenses change. Of all air gaps that change while zooming and focusing, an air gap that becomes the largest in the optical system at the shortest focal length lies between the first lens group and the second lens group, and a predetermined conditional expression is satisfied.SELECTED DRAWING: Figure 1

Claims

1. Starting from the object side and moving towards the image plane side, A first lens group having negative refractive power, A second lens group consisting of two or more lens groups, which as a whole has a positive refractive power, Equipped with, The first lens group is, A first lens consisting of a negative meniscus lens positioned closest to the object and with its convex surface facing the object, A second lens adjacent to the image plane side of the first lens and having negative refractive power It has, One of the two or more lens groups of the second lens group is designated as the focusing lens group, and each of the two or more lens groups of the second lens group is designated as a movable group during zooming. During zooming and focusing, the air gap between two adjacent lens groups changes, and the first and second lens groups are positioned with the maximum air gap in the optical system at the shortest focal length. The second lens group includes a lens unit having a negative refractive power that satisfies the following condition (4), and further satisfies the following conditions (5), (6), and (7)'' Zoom lens. -5.1<fn / ft×dn / Yta<-1.5...(4) 80°<θw<110°...(5) 80°<θt<110°...(6) 0.1<(R11-R12) / (R11+R12)<0.6...(7)'' however, fn: Focal length of the lens unit ft: Focal length of the entire system at the longest focal length. dn: Distance from the image plane side surface of the lens unit to the image plane when the lens unit is at its longest focal length. Yta: Maximum image height at the longest focal length. θw: Maximum half-angle of view at the shortest focal length. θt: Maximum half-angle of view at the longest focal length. R11: Radius of curvature of the object-side surface of the first lens. R12: Radius of curvature of the image plane side of the first lens. Let's assume that.

2. The first lens and the second lens satisfy the following condition (8). The zoom lens according to claim 1. 0.1<fL2 / fL1<2...(8) however, fL1: Focal length of the first lens fL2: Focal length of the second lens Let's assume that.

3. The following conditions must be met: The zoom lens according to claim 1. 2<|fFL| / fw<15...(9) however, fFL: Focal length of the aforementioned focusing lens group fw: Focal length of the entire system at the shortest focal length. Let's assume that.

4. The following conditions must be met: The zoom lens according to claim 1. 1.6<Yta / Ywa<3.2...(10) however, Ywa: Maximum image height at the shortest focal length. Yta: Maximum image height at the longest focal length. Let's assume that.

5. It includes a zoom lens and an image sensor that outputs an imaging signal corresponding to the optical image formed by the zoom lens, The aforementioned zoom lens is Starting from the object side and moving towards the image plane side, A first lens group having negative refractive power, A second lens group consisting of two or more lens groups, which as a whole has a positive refractive power, Equipped with, The first lens group is, A first lens consisting of a negative meniscus lens positioned closest to the object and with its convex surface facing the object, A second lens adjacent to the image plane side of the first lens and having negative refractive power It has, One of the two or more lens groups of the second lens group is designated as the focusing lens group, and each of the two or more lens groups of the second lens group is designated as a movable group during zooming. During zooming and focusing, the air gap between two adjacent lens groups changes, and the first and second lens groups are positioned with the maximum air gap in the optical system at the shortest focal length. The second lens group includes a lens unit having a negative refractive power that satisfies the following condition (4), and further satisfies the following conditions (5), (6), and (7)'' Imaging device. -5.1<fn / ft×dn / Yta<-1.5...(4) 80°<θw<110°...(5) 80°<θt<110°...(6) 0.1<(R11-R12) / (R11+R12)<0.6...(7)'' however, fn: Focal length of the lens unit ft: Focal length of the entire system at the longest focal length. dn: Distance from the image plane side surface of the lens unit to the image plane when the lens unit is at its longest focal length. Yta: Maximum image height at the longest focal length. θw: Maximum half-angle of view at the shortest focal length. θt: Maximum half-angle of view at the longest focal length. R11: Radius of curvature of the object-side surface of the first lens. R12: Radius of curvature of the image plane side of the first lens. Let's assume that.

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