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JP-7855771-B2 - Zoom lens and imaging device

JP7855771B2JP 7855771 B2JP7855771 B2JP 7855771B2JP-7855771-B2

Inventors

  • 岩本 俊二

Assignees

  • キヤノン株式会社

Dates

Publication Date
20260508
Application Date
20250728

Claims (10)

  1. A zoom lens consisting of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a rear group containing multiple lens groups, arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming. The lens group LR, which is positioned closest to the image among the rear group, moves towards the object side and then towards the image side when zooming from the wide-angle end to the telephoto end. When the focal length of the first lens group is f1, the focal length of the zoom lens at the telephoto end is ft, the amount of movement of the lens group LR when zooming from the wide-angle end to the telephoto end is mr, the distance on the optical axis from the image-side surface of the lens group LR to the image plane at the wide-angle end is bfw, the amount of movement of the third lens group when zooming from the wide-angle end to the telephoto end is m3 , and the focal length of the second lens group is f2, 0.20<f1/ft<0.40 -4.0<mr/bfw<-1.5 -7.0<m3/bfw<-2.5 -8.0<f1/f2<-4.5 A zoom lens characterized by satisfying the following conditional equation.
  2. The zoom lens according to claim 1, characterized in that the first lens group comprises one negative lens and three positive lenses.
  3. When the focal length of the lens group LR is denoted as fr, 0.3<fr/f1<2.8 A zoom lens according to claim 1 or 2 , characterized in that it satisfies the following conditional expression.
  4. When the amount of movement of the first lens group when zooming from the wide-angle end to the telephoto end is m1, -1.2<m1/f1<-0.4 A zoom lens according to any one of claims 1 to 3 , characterized in that it satisfies the following conditional expression.
  5. When the lateral magnification of the second lens group at the telephoto end is β2t and the lateral magnification of the second lens group at the wide-angle end is β2w, 3.0<β2t/β2w<12.0 A zoom lens according to any one of claims 1 to 4 , characterized in that it satisfies the following conditional expression.
  6. It further has an aperture diaphragm, When dpw is the distance along the optical axis from the aperture diaphragm to the image plane at the wide-angle end, and fw is the focal length of the zoom lens at the wide-angle end, 2.0<dpw/fw<7.0 A zoom lens according to any one of claims 1 to 5 , characterized in that it satisfies the following conditional expression.
  7. When Lt is the distance along the optical axis from the object-side surface of the zoom lens to the image plane at the telephoto end, 0.4<Lt/ft<1.2 A zoom lens according to any one of claims 1 to 6 , characterized in that it satisfies the following conditional expression.
  8. The zoom lens according to any one of claims 1 to 7 , characterized in that the lens group LR is composed of a single lens.
  9. When the Abbe number of the single lens is VdLR, 15.0<VdLR<50.0 The zoom lens according to claim 8 , characterized in that it satisfies the following condition.
  10. An imaging device characterized by having a zoom lens according to any one of claims 1 to 9 and an image sensor that receives an image formed by the zoom lens.

Description

This invention relates to a zoom lens suitable for digital cameras, video cameras, surveillance cameras, and the like, and an imaging device equipped with the same. Patent documents 1 to 3 disclose a zoom lens comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and multiple lens groups, arranged sequentially from the object side to the image side. Japanese Patent Publication No. 2017-049445Japanese Patent Publication No. 2018-146739Japanese Patent Publication No. 2019-20679 This is a cross-sectional view of the zoom lens in Example 1.This is an aberration diagram of the zoom lens at the wide-angle end, intermediate zoom position, and telephoto end in Example 1.This is a cross-sectional view of the zoom lens in Example 2.This is an aberration diagram of the zoom lens at the wide-angle end, intermediate zoom position, and telephoto end in Example 2.This is a cross-sectional view of the zoom lens in Example 3.This is an aberration diagram of the zoom lens at the wide-angle end, intermediate zoom position, and telephoto end in Example 3.This is a cross-sectional view of the zoom lens in Example 4.This is an aberration diagram of the zoom lens at the wide-angle end, intermediate zoom position, and telephoto end in Example 4.This is a cross-sectional view of the zoom lens in Example 5.This is an aberration diagram of the zoom lens at the wide-angle end, intermediate zoom position, and telephoto end in Example 5.This is a schematic diagram of an imaging device equipped with a zoom lens for each embodiment. The embodiments of the present invention will be described in detail below with reference to the drawings. Figures 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lens (optical system) L0 of Examples 1 to 5 at infinity focus. The zoom lens L0 in each example is an optical system used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras. In each cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The zoom lens L0 in each embodiment is composed of multiple lens groups. In each cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the i-th lens group. In each embodiment, a lens group is a collection of lenses that move or remain stationary as a single unit during zooming. That is, in the zoom lens L0 of each embodiment, the distance between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end. Note that a lens group may consist of a single lens or multiple lenses. Furthermore, a lens group may include an aperture diaphragm. SP is the aperture diaphragm. In each embodiment, the aperture diaphragm SP is included in the third lens group L3, but is not limited to this. IP is the image plane, and when the zoom lens L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera, the imaging plane of an image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is located there. When the zoom lens L0 of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface corresponding to the film plane is placed on the image plane IP. In each cross-sectional view, the solid arrows schematically show the movement trajectory of each lens group when focusing at infinity during zooming from the wide-angle end to the telephoto end. In each embodiment, the wide-angle end and telephoto end refer to the zoom positions when each lens group of the zoom lens L0 is located at the ends of the range in which it can move along the optical axis OA due to its mechanism. Figures 2, 4, 6, 8, and 10 are aberration diagrams of zoom lenses L0 in Examples 1 to 5, respectively. In each aberration diagram, (A) is the aberration diagram of zoom lens L0 at the wide-angle end, (B) is the aberration diagram of zoom lens L0 at the intermediate zoom position, and (C) is the aberration diagram of zoom lens L0 at the telephoto end. In the spherical aberration diagram, Fno is the F-number and indicates the amount of spherical aberration for the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS indicates the amount of astigmatism at the sagittal image plane, and ΔM indicates the amount of astigmatism at the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration at the g-line is shown. ω is the imaging half-angle of view (degrees). Conventionally, zoom lenses are known that consist of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive