Zoom lens and imaging device having the same

Abstract

To provide a zoom lens capable of reducing the occurrence of ghost while having high optical performance.SOLUTION: The zoom lens L0 includes a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, and two or more lens units. During zooming, the first lens unit L1 moves, and an interval between adjacent lens units changes. A refractive power of a negative lens A arranged closest to the object side among the negative lenses included in the first lens group L1 is 1.89 or more, and the negative lens A and a lens B arranged adjacent to the image side of the negative lens A satisfy a predetermined relationship.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a zoom lens and the like, and is suitable for imaging devices such as digital video cameras, digital still cameras, broadcast cameras, and silver halide film cameras.

Background Art

[0002] For landscape photography, celestial photography, etc., wide-angle lenses are widely used. Wide-angle lenses are required to achieve high optical performance while achieving a wide angle of view.

[0003] In Patent Document 1, a zoom lens that is wide-angle and has high performance is disclosed by employing a plurality of negative lenses in the first lens group to gently bend off-axis light rays.

Prior Art Documents

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the zoom lens described in Patent Document 1, since the opening angle of the first lens is deep, unnecessary light that is reflected obliquely with respect to the lens surface on the object-side lens surface of the second lens is reflected on the image-side lens surface of the first lens and may reach the image plane. When such unnecessary light reaches the image plane, ghosts occur on the photograph, which is not preferable.

[0006] Therefore, an object of the present invention is to provide a zoom lens that can reduce the occurrence of ghosts while having high optical performance.

Means for Solving the Problems

[0007] ​​​​​​​​The zoom lens of the present invention has a first lens group with negative refractive power, a second lens group with positive refractive power, and two or more lens groups arranged in order from the object side to the image side, wherein the first lens group moves during zooming, and the spacing between adjacent lens groups changes. The first lens group consists of three negative lenses and a positive lens positioned on the image side of the three negative lenses. The refractive index of negative lens A, which is positioned closest to the object among the negative lenses included in the first lens group, is 1.89 or higher. ,before Ra is the radius of curvature of the image-side lens surface of the negative lens A, and the The negative lens A is positioned adjacent to the image side. When Rb is the radius of curvature of the object-side lens surface of lens B, Da is the air gap between the negative lens A and lens B, and Db is the air gap between lens B and the lens adjacent to it on the image side, 2.0 <Ra / Da<100 10 <Rb / Db<100 It is characterized by satisfying the following conditional expression. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a zoom lens that has high optical performance while reducing the occurrence of ghosting. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of the zoom lens of Example 1. [Figure 2] This is an aberration diagram of the zoom lens of Example 1. [Figure 3] This is a cross-sectional view of the zoom lens of Example 2. [Figure 4] This is an aberration diagram of the zoom lens in Example 2. [Figure 5] This is a cross-sectional view of the zoom lens of Example 3. [Figure 6] This is an aberration diagram of the zoom lens in Example 3. [Figure 7] This is a cross-sectional view of the zoom lens of Example 4. [Figure 8] This is an aberration diagram of the zoom lens in Example 4. [Figure 9]It is a lens cross-sectional view of the zoom lens of Example 5. [Figure 10] It is an aberration diagram of the zoom lens of Example 5. [Figure 11] It is a lens cross-sectional view of the zoom lens of Example 6. [Figure 12] It is an aberration diagram of the zoom lens of Example 6. [Figure 13] It is a schematic diagram showing an imaging device. [Figure 14] It is a schematic diagram showing the optical path of unwanted light.

Mode for Carrying Out the Invention

[0010] Hereinafter, examples of the zoom lens of the present invention and an imaging device having the same will be described based on the accompanying drawings. <00000�4>

[0011] FIGS. 1, 3, 5, 7, 9, and 11 are cross-sectional views of the zoom lenses L0 of Examples 1 to 6, respectively. The zoom lens L0 of each example is a zoom lens used in an imaging device such as a digital video camera, a digital still camera, a broadcast camera, a silver halide film camera, a surveillance camera, or an in-vehicle camera.

[0012] In each lens cross-sectional view, the left side is the object side and the right side is the image side. Incidentally, the zoom lens L0 of each example may be used as a projection lens such as a projector. In this case, the left side is the screen side and the right side is the side of the projected image.

[0013] The zoom lens L0 of each embodiment has a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, and two or more lens groups arranged sequentially from the object side to the image side. In each cross-sectional view, Li represents the i-th lens group counting from the object side (i is a natural number). In this specification, a lens group is a collection of lenses that move or remain stationary as a whole during zooming. That is, the distance between adjacent lens groups changes during zooming. Furthermore, each lens group may consist of one lens or multiple lenses. Furthermore, each lens group may include an aperture diaphragm.

[0014] Furthermore, the arrows shown in each lens cross-sectional diagram represent the movement trajectory when zooming from the wide-angle end to the telephoto end, and the movement trajectory when focusing from infinity to close distance.

[0015] In each lens cross-sectional view, SP is the aperture diaphragm. IP is the image plane, and when the zoom lens of each embodiment is used in a digital still camera or digital video camera, the image plane of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed on it. When the zoom lens of each embodiment is used as a shooting zoom lens for a silver halide film camera, a photosensitive surface corresponding to the film plane is placed on the image plane IP.

[0016] Figures 2, 4, 6, 8, 10, and 12 are aberration diagrams of the zoom lenses of Examples 1 to 6, respectively. In each aberration diagram, (A) is the aberration diagram at the wide-angle end, and (B) is the aberration diagram at the telephoto end.

[0017] 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, S indicates the amount of aberration at the sagittal image plane, and M indicates the amount of aberration 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 lateral chromatic aberration at the g-line is shown. ω is the half-angle of view (°).

[0018] Next, we will describe the characteristic configurations of the zoom lenses in each embodiment.

[0019] In the zoom lenses of each embodiment, the refractive power of the first lens group L1 is made negative, thereby shifting the entrance pupil closer to the object and reducing the diameter of the front element (the lens positioned closest to the object). Furthermore, the refractive power of the second lens group L2 is made positive, causing the on-axial marginal rays diverged by the first lens group L1 to converge, thereby reducing the diameter of the lens groups L2 and beyond. In addition, by providing two or more lens groups on the image side of the positive second lens group L2 and moving the first lens group L1 during zooming, aberrations are effectively corrected over a wide zoom range.

[0020] Furthermore, in the zoom lens L0 of each embodiment, the refractive index of the negative lens A closest to the object among the negative lenses in the first lens group L1 is set to 1.89 or higher. In addition, it is configured to satisfy the following conditional equation. Here, Ra is the radius of curvature of the image-side lens surface of negative lens A. Rb is the radius of curvature of the object-side lens surface of lens B, which is positioned adjacent to the image side of negative lens A. Da is the air gap between negative lens A and lens B. Db is the air gap between lens B and the lens positioned adjacent to the image side of lens B. 2.0 <Ra / Da<100 (1) 10 <Rb / Db<100 (2) In wide-angle lenses, the diameter of the first lens, which is positioned closest to the object in the first lens group, tends to be larger, and the opening angle also tends to be larger. In this case, as shown in Figure 14, light reflected from the object-side lens surface of the second lens, which is positioned on the image side of the first lens, can be further reflected from the image-side lens surface of the first lens, forming an optical path that reaches the image plane. In this case, since both the first and second reflections are oblique reflections with respect to the lens surface, the reflection intensity is relatively large and tends to be noticeable as ghosting.

[0021] Therefore, in the zoom lens L0 of each embodiment, the refractive index of negative lens A is set to 1.89, thereby providing the necessary refractive power to negative lens A while making the opening angle gentler. Furthermore, by making the curvature of the image-side lens surface of negative lens A and the object-side lens surface of lens B gentler within the range that satisfies conditions (1) and (2), off-axis rays are reflected at an angle close to perpendicular to the lens surface, thus suppressing the intensity of ghosting. However, if the upper limit values ​​of conditions (1) and (2) are exceeded, it becomes difficult to provide the necessary refractive power to negative lens A and lens B, which is undesirable.

[0022] With the above configuration, it becomes possible to create a zoom lens that has high optical performance while reducing the occurrence of ghosting.

[0023] Furthermore, it is preferable that at least one of the upper or lower limits of the numerical range in either condition (1) or (2) be within the range of the following condition (1a) and (2a). 2.3 <Ra / Da<50 (1a) 11 <Rb / Db<50 (2a) More preferably, at least one of the upper or lower limits of the numerical range of either conditional expression (1) or (2) is within the range of the following conditional expressions (1b) and (1b). 2.6 <Ra / Da<10 (1b) 11.5 <Rb / Db<30 (2b) Furthermore, by setting the refractive index of negative lens A to a value greater than 1.89, it becomes possible to make the opening angle of negative lens A more favorable from the standpoint of ghost reduction.

[0024] Next, we will describe the preferred configuration of the zoom lens L0 in each embodiment.

[0025] It is preferable that lens B, positioned adjacent to the image side of negative lens A, is also a negative lens. With this configuration, negative lenses are arranged in a continuous manner together with negative lens A, making it possible to gently bend off-axis light rays. This effectively reduces astigmatism and field curvature, especially at the wide-angle end.

[0026] Furthermore, it is preferable that the first lens group L1 consists of three negative lenses and a positive lens arranged sequentially from the object side to the image side. By arranging three negative lenses in a sequence, astigmatism and field curvature at the wide-angle end can be further reduced. Also, by placing the positive lens closest to the image, chromatic aberration at the wide-angle end can be further reduced. Next, we will describe the preferred conditional expressions that should be satisfied in the zoom lens L0 of each embodiment.

[0027] The zoom lens L0 of each embodiment preferably satisfies one or more of the following conditional expressions. 1.80 <NdB (3) 2.0 <d / fw<15 (4) 1.5 <d2 / fw<5.0 (5) 0.15 <GL / TL<0.30 (6) -20 < 100 × (y - y0) / y0 < -8 (7) -2.5 <f1 / fw<-0.8 (8) -3.5 <fa / fw<-1.5 (9) -3.5 <fb / fw<-0.8 (10) 1.2 <ft / fw<2.1 (11) Here, NdB is the refractive index of lens B at the d line. d is the distance from the image-side lens surface of negative lens A to the aperture diaphragm SP at the wide-angle end. fw is the total focal length of zoom lens L0 at the wide-angle end. d2 is the distance from the image-side lens surface of lens B to the aperture diaphragm SP at the wide-angle end. GL is the distance from the lens surface closest to the object to the lens surface closest to the image in the first lens group L1. TL is the distance from the lens surface closest to the object to the image plane IP (paraxial imaging plane) in zoom lens L0 at the wide-angle end. y is the maximum real image height at the wide-angle end. y0 is the ideal image height at the angle of view corresponding to the maximum real image height y at the wide-angle end (maximum angle of view). f1 is the focal length of the first lens group L1. fa is the focal length of negative lens A. fb is the focal length of lens B. ft is the total focal length of zoom lens L0 at the telephoto end.

[0028] The technical meaning of each conditional expression is explained below.

[0029] If the value falls below the lower limit of condition (3), the opening angle required to impart the desired refractive power to lens B becomes deeper, which is undesirable because it can easily lead to reflections from the object-side lens surface of lens B.

[0030] Conditional equation (4) represents the ratio of the distance from the image-side lens surface of negative lens A to the aperture diaphragm SP at the wide-angle end to the total focal length of the system at the wide-angle end. If the upper limit is exceeded, the distance from the image-side lens surface of negative lens A to the aperture diaphragm SP at the wide-angle end becomes too long, making it easy for negative lens A to become larger. If the lower limit is exceeded, it becomes difficult to sufficiently suppress the intensity of ghosting caused by unwanted light reflected between negative lens A and lens B.

[0031] Conditional equation (5) represents the ratio of the distance from the image-side lens surface of lens B to the aperture diaphragm SP at the wide-angle end to the total focal length of the system at the wide-angle end. If the upper limit is exceeded, the distance from the image-side lens surface of lens B to the aperture diaphragm SP at the wide-angle end becomes too long, making it easy for lens B to become larger. If the lower limit is exceeded, it becomes difficult to sufficiently suppress the intensity of ghosting caused by unwanted light reflected between negative lens A and lens B.

[0032] Conditional equation (6) represents the ratio of the distance from the object-side lens surface to the image-side lens surface of the first lens group L1 to the distance from the object-side lens surface to the paraxial image plane of the entire system at the wide-angle end. If the upper limit is exceeded, the distance from the object-side lens surface to the image-side lens surface of the first lens group L1 becomes too long, causing the distance from the aperture diaphragm SP to the first lens (the lens positioned closest to the object) to become too long. As a result, the first lens becomes larger. If the lower limit is fallen below, the distance from the object-side lens surface to the paraxial image plane of the entire system at the wide-angle end becomes too long, causing the zoom lens L0 to become larger.

[0033] Conditional equation (7) represents the distortion rate at the wide-angle end. The ideal image height y0 is calculated as f × tanθ, where f is the focal length of the entire system at the wide-angle end, and θ is the angle (half-angle of view) between the light ray incident on the object side of the entire system closest to the object and the optical axis, corresponding to the maximum real image height y. The real image height y can be determined by the maximum radius of the image circle of the zoom lens L0. If the upper limit is exceeded, it becomes necessary to loosen the refractive power within the first lens group L1 in order to reduce the absolute value of the distortion rate, which increases the distance from the lens surface closest to the object to the image plane IP, making it easier for the zoom lens L0 to become larger. If the lower limit is exceeded, the absolute value of the distortion rate becomes too large, the peripheral part of the image is greatly compressed, and it becomes difficult to obtain a sufficiently high-quality image.

[0034] Condition (8) represents the ratio of the focal length of the first lens group L1 to the total focal length of the entire system at the wide-angle end. If the upper limit is exceeded, the absolute value of the focal length of the first lens group L1 becomes too short, resulting in excessive refractive power and large astigmatism, field curvature, and chromatic aberration at the wide-angle end, which is undesirable. If the lower limit is exceeded, the absolute value of the focal length of the first lens group L1 becomes too long, increasing the distance from the lens surface closest to the object to the image plane IP, resulting in a larger image size.

[0035] Condition (9) represents the ratio of the focal length of negative lens A to the total focal length of the system at the wide-angle end. If the upper limit is exceeded, the absolute value of the focal length of negative lens A becomes too short, the refractive power becomes too strong, and chromatic aberration becomes particularly large at the wide-angle end. If the lower limit is exceeded, the absolute value of the focal length of negative lens A becomes too long, the distance from the lens surface closest to the object to the image plane IP becomes long, and the diameter of negative lens A becomes large.

[0036] Condition (10) represents the ratio of the focal length of lens B to the total focal length of the system at the wide-angle end. If the upper limit is exceeded, the absolute value of the focal length of lens B becomes too short, resulting in excessive refractive power and large astigmatism and chromatic aberration, especially at the wide-angle end. If the lower limit is exceeded, the absolute value of the focal length of lens B becomes too long, increasing the distance from the lens surface closest to the object to the image plane IP, and thus increasing the diameter of lens B.

[0037] Condition (11) represents the zoom ratio. If the upper limit is exceeded, the amount of movement of each lens group tends to increase, and the zoom lens L0 tends to become larger in order to secure space for movement. If the lower limit is exceeded, the zoom ratio becomes too small, making it difficult for the zoom lens to function adequately.

[0038] Furthermore, it is preferable to set at least one of the upper and lower limits of conditional expressions (3) to (11) to the following numerical range. 1.82 <NdB (3a) 2.3 <d / fw<10 (4a) 2.0 <d2 / fw<4.0 (5a) 0.17 <GL / TL<0.27 (6a) -19 < 100 × (y - y0) / y0 < -11 (7a) -2.0 <f1 / fw<-1.0 (8a) -3.1 <fa / fw<-1.7 (9a) -3.0 <fb / fw<-1.0 (10a) 1.3 <ft / fw<2.0 (11a) Furthermore, it is even more preferable to set at least one of the upper and lower limits of conditional expressions (3) to (11) to the following numerical range. 1.84 <NdB (3b) 2.7 <d / fw<5 (4b) 2.3 <d2 / fw<3.5 (5b) 0.19 <GL / TL<0.24 (6b) -18 < 100 × (y - y0) / y0 < -14 (7b) -1.8 <f1 / fw<-1.2 (8b) -2.8 <fa / fw<-1.9 (9b) -2.7 <fb / fw<-1.2 (10b) 1.4 <ft / fw<1.9 (11b) Next, we will describe the details of the configuration of the zoom lens L0 in each embodiment.

[0039] [Example 1] The zoom lens L0 of Example 1 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with positive refractive power, arranged sequentially from the object side to the image side. By alternating the arrangement of lens groups with negative and positive refractive power, chromatic aberration and axial chromatic aberration are appropriately corrected. Furthermore, by making the fifth lens group L5 positive, a wide angle of view is achieved while ensuring back focus, and ghosting caused by unwanted light reflected between the image plane IP (or a low-pass filter or IR cut filter that may be placed on the object side) and the fifth lens group L5 can be suppressed. In addition, the third lens group L3 is moved during focusing, and the object side of the third lens group L3 has a concentric shape with a concave surface relative to the aperture diaphragm SP. This suppresses fluctuations in field curvature and astigmatism even when the third lens group L3 moves during focusing, resulting in improved performance across the entire image. Furthermore, by composing the third lens group L3 with two elements, a positive lens and a negative lens, it is possible to suppress fluctuations in lateral chromatic aberration and axial chromatic aberration even when moving along the optical axis.

[0040] Furthermore, the trajectory of the first lens group during zooming is configured to move monotonically towards the image side from the wide-angle end to the telephoto end. This increases the absolute value of the focal length of the first lens group (weakening the refractive power), thereby improving the performance of the zoom lens L0.

[0041] [Example 2] In Example 2, the third lens group L3, which is the focusing group, is composed of a single negative lens, compared to Example 1. This makes it possible to miniaturize the third lens group L3, which moves during focusing.

[0042] [Example 3] The zoom lens L0 of Example 3 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with negative refractive power, and a fifth lens group L5 with positive refractive power, arranged in order from the object side to the image side. By making the fourth lens group L4 with negative refractive power, chromatic aberration occurring in the fifth lens group L5 with positive refractive power can be effectively corrected. In addition, by placing the positive lens closest to the object, negative distortion aberration occurring in the first lens group L1 is reduced, and by suppressing the distortion rate, the compression rate at the edges of the image is reduced and the resolution is improved.

[0043] Furthermore, by joining the fourth and fifth lenses, the intensity of unwanted light reflected between the fourth and fifth lenses is reduced, thereby suppressing ghosting.

[0044] Furthermore, by moving the fifth lens group L5 toward the object towards the telephoto end, the fifth lens group L5 can be positioned at a low height of off-axis rays at the telephoto end, resulting in a smaller diameter.

[0045] [Example 4] The zoom lens L0 of Example 4 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, and a sixth lens group L6 with positive refractive power. By dividing the positive refractive power before and after the aperture diaphragm SP into two lens groups and moving them independently during zooming, spherical aberration and coma aberration are well corrected over a wide zoom range.

[0046] [Example 5] The zoom lens L0 of Example 5 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power, arranged in order from the object side to the image side. By making the fourth lens group L4 positive and the fifth lens group L5 negative, the position of the front principal point of the combined fourth lens group L4 and fifth lens group L5 can be moved towards the object side, shortening the back focus and thus allowing the zoom lens L0 to be miniaturized.

[0047] [Example 6] The zoom lens L0 of Example 5 is composed of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. By providing one positive and one negative lens in the fourth lens group L4, chromatic aberration is well corrected over a wide zoom range.

[0048] The zoom lens L0 in each of the above embodiments may also be used in an imaging device that has an image processing function to correct aberrations (distortion aberration and chromatic aberration).

[0049] The numerical values ​​corresponding to Examples 1 to 6 are shown below.

[0050] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incidence side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of the optical element. Note that the Abbe number νd of a certain material is given by Nd, NF, NC, and Ng, respectively, when the refractive indices of the Fraunhofer lines at d-line (587.6 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.8 nm), respectively. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0051] Furthermore, if the optical surface is aspherical, the sign * is added to the right of the surface number. The aspherical shape is defined as follows, where X is the displacement from the surface vertex in the optical axis direction, h is the height from the optical axis perpendicular to the optical axis, R is the paraaxial radius of curvature, k is the cone constant, and A4, A6, A8, A10, A12, ... are the aspherical coefficients of each order. x=( h 2 / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 ]+A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 This is expressed as follows. Note that "e±XX" in each aspherical coefficient is "×10± XX It means "...".

[0052] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd Effective diameter 1 45.932 1.80 2.00100 29.1 36.70 2 19.277 7.27 29.17 3 81.393 1.40 1.84943 42.6 27.28 4 20.862 6.78 24.31 5 -32.534 1.30 1.49700 81.5 24.21 6 39.245 0.34 25.06 7 36.818 6.92 1.78582 36.7 25.39 8 -45.455 (variable) 25.35 9 46.667 1.80 1.60738 56.8 11.23 10 ∞ 3.00 10.63 11 (aperture) ∞ 3.00 10.34 12 88.981 1.00 1.80400 46.5 10.34 13 19.604 2.53 1.71300 53.9 10.25 14 -123.595 2.00 10.21 15 16.661 2.78 1.51633 64.1 10.41 16 47.619 4.87 10.69 17 34.510 1.00 1.90043 37.4 12.26 18 11.580 5.34 1.49700 81.5 12.24 19 -36.852 (variable) 13.26 20 -26.584 3.17 1.77250 49.6 14.02 21 -13.000 1.10 1.85107 36.9 14.79 22 -225.385 (variable) 16.29 23* -50.000 3.00 1.53110 55.9 21.52 24* -34.796 (variable) 23.70 25 -157.498 4.50 1.79008 48.6 36.60 26 -45.000 13.50 37.47 Image plane ∞ Aspherical data Page 23 K = 0.00000e+000 A 4=-7.50939e-005 A 6= 6.59902e-007 A 8=-4.44635e-009 A10= 1.37303e-011 Page 24 K = 0.00000e+000 A 4=-3.09530e-005 A 6= 4.44991e-007 A 8=-1.75524e-009 A10= 4.51720e-012 Various data Zoom ratio 1.89 Wide-angle, Medium, Telephoto Focal length 15.45 20.34 29.15 F-numbers: 4.60, 5.25, 6.32 Half-angle (°): 49.36, 44.61, 36.19 Image height 18.00 20.06 21.33 Lens length: 115.26 x 109.84 x 107.01 BF 13.50 13.50 13.50 d 8 25.18 13.47 1.21 d19 2.67 3.30 5.13 d22 7.82 7.19 5.36 d24 1.20 7.49 16.92 Entrance pupil position 17.00 15.69 13.74 Exit pupil position -64.71 -86.93 -130.67 Front principal point position 29.40 31.91 37.00 Back principal point position -1.95 -6.84 -15.65 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -25.31 25.82 -0.46 -26.81 2 9 24.31 27.31 9.72 -14.84 3 20 -31.88 4.27 0.06 -2.33 4 23 201.66 3.00 6.03 4.20 5 25 78.36 4.50 3.46 0.99 Single lens data Lens starting plane, focal length 1 1 -34.34 2 3 -33.38 3 5 -35.58 4 7 26.88 5 9 76.83 6 12 -31.48 7 13 23.91 8 15 48.16 9 17 -19.76 10 18 18.40 11 20 29.90 12 21 -16.25 13 23 201.66 14 25 78.36

[0053] [Numerical Example 2] Unit: mm Surface data Face number rd nd νd Effective diameter 1 39.485 1.80 2.00100 29.1 35.98 2 19.277 6.35 29.06 3 81.393 1.40 1.90043 37.4 27.89 4 21.695 6.53 24.75 5 -37.674 1.30 1.49700 81.5 24.58 6 45.445 1.55 24.80 7 48.066 6.33 1.80610 33.3 25.36 8 -58.121 (variable) 25.19 9 75.709 2.91 1.63930 44.9 12.62 10 -99.071 5.00 11.75 11 (aperture) ∞ 3.00 10.25 12 90.807 1.00 1.80400 46.5 10.20 13 21.203 2.41 1.71300 53.9 10.11 14 -125.965 2.00 10.05 15 14.434 3.39 1.48749 70.2 10.46 16 47.619 3.38 10.70 17 40.616 1.00 1.90043 37.4 11.54 18 10.473 5.52 1.49700 81.5 11.52 19 -36.785 (variable) 12.72 20 -24.105 1.10 1.80100 35.0 14.79 21 -332.736 (variable) 15.94 22* -50.000 3.00 1.53110 55.9 21.21 23* -33.834 (variable) 23.27 24 -186.603 4.91 1.80400 46.5 37.46 25 -45.000 13.50 38.41 Image plane ∞ Aspherical data Page 22 K = 0.00000e+000 A 4=-3.17244e-005 A 6= 2.39294e-007 A 8=-2.65521e-009 A10= 1.39956e-011 Page 23 K = 0.00000e+000 A 4= 7.78280e-006 A 6= 1.77889e-007 A 8=-9.23774e-010 A10= 4.78158e-012 Various data Zoom ratio 1.89 Wide-angle, Medium, Telephoto Focal length 15.45 20.53 29.15 F-number 4.60 5.27 6.36 Half-angle (°): 49.88, 45.31, 36.58 Image height 18.34 20.75 21.63 Lens length: 115.28 mm, 109.06 mm, 106.60 mm BF 13.50 13.50 13.50 d 8 24.84 12.64 1.20 d19 2.86 4.14 6.51 d21 9.00 7.72 5.35 d23 1.20 7.19 16.16 Entrance pupil position 17.59 16.29 14.57 Exit pupil position -64.63 -84.63 -125.12 Front principal point position 29.98 32.52 37.59 Back principal point position -1.95 -7.03 -15.65 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -24.39 25.25 0.53 -24.54 2 9 24.70 29.61 10.23 -15.77 3 20 -32.50 1.10 -0.05 -0.66 4 22 185.12 3.00 5.69 3.85 5 24 72.63 4.91 3.53 0.85 Single lens data Lens starting plane, focal length 1 1 -39.38 2 3 -33.22 3 5 -41.23 4 7 33.53 5 9 67.57 6 12 -34.63 7 13 25.63 8 15 41.11 9 17 -15.92 10 18 17.06 11 20 -32.50 12 22 185.12 13 24 72.63

[0054] [Numerical Example 3] Unit: mm Surface data Face number rd nd νd Effective diameter 1 52.248 2.62 1.51633 64.1 28.75 2 140.000 0.15 26.67 3 26.292 0.80 1.90043 37.4 20.18 4 10.697 3.20 15.85 5 60.521 0.80 1.95375 32.3 15.54 6 10.056 3.71 13.19 7 -25.717 0.80 1.49700 81.5 13.14 8 14.607 4.06 1.90366 31.3 13.41 9 -55.225 (variable) 13.10 10 -101.139 2.20 1.48749 70.2 7.88 11 -21.879 2.89 8.23 12 (aperture) ∞ 1.75 8.52 13 13.538 5.13 1.48749 70.2 8.74 14 -10.601 1.00 1.77250 49.6 8.16 15 -22.350 3.58 8.16 16 20.040 0.70 1.90043 37.4 9.69 17 8.853 4.71 1.49700 81.5 9.63 18 -21.100 (variable) 10.46 19 -19.295 0.70 1.91082 35.3 10.75 20 -100.891 (variable) 11.26 21* -24.999 1.50 1.53110 55.9 14.14 22* -26.775 (variable) 15.39 23 -182.094 4.42 1.60311 60.6 18.76 24 -22.000 (Variable) 20.18 Image plane ∞ Aspherical data Page 21 K = 0.00000e+000 A 4=-1.91538e-004 A 6= 5.07567e-006 A 8=-8.17417e-008 A10= 5.32571e-010 Page 22 K = 0.00000e+000 A 4=-6.30674e-005 A 6= 4.22634e-006 A 8=-5.18522e-008 A10= 2.90202e-010 Various data Zoom ratio 1.47 Wide-angle, Medium, Telephoto Focal length 9.97 12.66 14.64 F-number 3.50 3.94 4.23 Half-angle (°): 49.63, 44.83, 41.54 Image height 11.72 12.58 12.97 Lens length: 72.73, 71.60, 71.78 BF 10.06 12.25 14.3 d 9 10.09 4.76 1.89 d18 1.44 2.18 2.76 d20 5.42 4.68 4.11 d22 0.99 3.00 4.00 d24 10.06 12.25 14.31 Entrance pupil position 11.15 10.50 10.06 Exit pupil position -51.09 -59.37 -63.10 Front principal point position 19.49 20.92 21.93 Back principal point position 0.09 -0.40 -0.33 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -12.21 16.14 2.87 -11.14 2 10 15.46 21.97 9.98 -10.48 3 19 -26.30 0.70 -0.09 -0.45 4 21 -1004.27 1.50 -19.52 -20.90 5 23 41.06 4.42 3.10 0.37 Single lens data Lens starting plane, focal length 1 1 159.82 2 3 -20.53 3 5 -12.74 4 7 -18.62 5 8 13.15 6 10 56.75 7 13 13.11 8 14 -27.11 9 16 -18.15 10 17 13.24 11 19 -26.30 12 21 -1004.27 13 23 41.06

[0055] [Numerical Example 4] Unit: mm Surface data Face number rd nd νd Effective diameter 1 40.925 1.80 2.05090 26.9 33.27 2 21.334 4.87 27.89 3 79.995 1.40 1.95375 32.3 26.78 4 24.034 4.47 23.95 5 -91.221 1.30 1.49700 81.5 23.68 6 31.289 2.00 22.62 7 59.784 3.91 1.82097 22.5 22.63 8 -85.008 (variable) 22.27 9 100.000 1.00 1.63980 34.5 9.42 10 20.000 2.47 1.88645 38.8 9.51 11 -90.366 3.00 9.49 12 (aperture) ∞ (variable) 9.12 13 15.735 3.66 1.52647 69.8 11.78 14 -17.484 0.59 11.90 15 -16.171 1.00 1.90043 37.4 11.76 16 44.055 5.10 1.49700 81.5 12.35 17 -13.352 (variable) 13.43 18 -14.286 1.10 1.87587 39.9 13.46 19 -74.875 (variable) 14.64 20 5903.921 2.85 1.49700 81.5 19.07 21* -33.757 (variable) 20.14 22 -98.558 3.58 1.80400 46.5 26.77 23 -45.000 (variable) 28.10 Image plane ∞ Aspherical data Page 21 K = 0.00000e+000 A 4= 6.79219e-005 A 6= 1.06797e-007 A 8= 1.34694e-009 A10=-5.68552e-012 Various data Zoom ratio 1.82 Wide-angle, Medium, Telephoto Focal length 16.00 20.22 29.17 F-numbers: 4.60, 4.97, 5.66 Half-angle (°): 48.58, 45.05, 36.57 Image height 18.14 20.26 21.64 Lens length: 99.94, 95.51, 91.54 BF 13.04 19.20 30.42 d 8 22.55 12.93 1.20 d12 4.71 4.81 4.91 d17 2.26 2.44 3.69 d19 5.43 4.78 3.15 d21 7.84 7.24 4.07 d23 13.04 19.20 30.42 Entrance pupil position 17.09 15.78 13.40 Exit pupil position -53.81 -50.02 -38.59 Front principal point position 29.26 30.09 30.24 Back principal point position -2.96 -1.02 1.25 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -22.38 19.75 2.35 -15.16 2 9 35.44 6.47 0.93 -4.01 3 13 27.72 10.35 4.14 -3.77 4 18 -20.33 1.10 -0.14 -0.73 5 20 67.55 2.85 1.89 -0.01 6 22 100.02 3.58 3.55 1.62 Single lens data Lens starting plane, focal length 1 1 -44.50 2 3 -36.47 3 5 -46.71 4 7 43.28 5 9 -39.27 6 10 18.67 7 13 16.35 8 15 -13.03 9 16 21.24 10 18 -20.33 11 20 67.55 12 22 100.02

[0056] [Numerical Example 5] Unit: mm Surface data Face number rd nd νd Effective diameter 1 50.254 1.80 2.05090 26.9 36.85 2 19.398 6.82 29.33 3 135.195 1.40 1.95375 32.3 28.56 4 30.089 5.41 26.58 5 -47.967 1.30 1.49700 81.5 26.52 6 37.077 0.19 27.13 7 35.891 7.61 1.82283 30.8 27.32 8 -62.958 (variable) 27.08 9 100.000 1.00 1.53458 47.9 10.67 10 20.000 2.47 1.84733 42.8 10.74 11 -7293.532 3.20 10.64 12 (aperture) ∞ 6.70 10.31 13 20.310 3.45 1.56657 68.8 11.12 14 -23.439 0.77 11.40 15 -17.148 1.00 1.90043 37.4 11.36 16 58.384 4.41 1.49700 81.5 12.04 17 -15.093 (variable) 13.17 18 -22.042 1.10 1.85000 35.0 14.06 19 -73.968 (variable) 14.82 20* 123.352 4.61 1.51380 54.6 21.29 21* -32.035 (variable) 22.35 22 -43.536 1.50 1.88449 39.0 23.28 23 -87.118 (variable) 24.42 Image plane ∞ Aspherical data Page 20 K = 0.00000e+000 A 4= 7.78121e-006 A 6=-1.41841e-007 A 8= 1.32693e-009 A10=-7.58503e-012 Page 21 K = 0.00000e+000 A 4= 4.93770e-005 A 6=-4.36212e-008 A 8= 1.50692e-009 A10=-6.87281e-012 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 15.53 20.47 29.15 F-numbers: 4.60, 5.01, 5.59 Half-angle (°): 49.20, 43.44, 35.66 Image height 18.00 19.38 20.92 Lens length: 120.00 x 109.11 x 99.49 BF 15.70 23.59 24.20 d 8 32.68 17.17 1.20 d17 4.32 4.50 5.63 d19 10.14 6.17 3.93 d21 2.40 2.92 9.77 d23 15.70 23.59 24.20 Entrance pupil position 17.77 16.10 13.44 Exit pupil position -40.00 -33.43 -33.85 Front principal point position 28.97 29.22 27.95 Back principal point position 0.16 3.13 -4.95 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -26.49 24.53 -0.82 -23.99 2 9 25.34 23.00 10.82 -11.53 3 18 -37.30 1.10 -0.25 -0.86 4 20 50.00 4.61 2.44 -0.63 5 22 -100.01 1.50 -0.81 -1.62 Single lens data Lens starting plane, focal length 1 1 -30.99 2 3 -40.84 3 5 -41.86 4 7 28.78 5 9 -46.97 6 10 23.54 7 13 19.77 8 15 -14.63 9 16 24.62 10 18 -37.30 11 20 50.00 12 22 -100.01

[0057] [Numerical Example 6] Unit: mm Surface data Face number rd nd νd Effective diameter 1 46.382 1.80 2.05090 26.9 36.85 2 19.375 6.91 29.33 3 148.313 1.40 1.95375 32.3 28.56 4 28.489 5.81 26.58 5 -43.395 1.30 1.49700 81.5 26.52 6 35.729 0.20 27.13 7 35.165 8.11 1.79522 32.0 27.32 8 -51.640 (variable) 27.08 9 100.000 1.00 1.51753 52.4 10.67 10 20.000 2.47 1.82588 45.0 10.74 11 -7234.968 3.06 10.64 12 (aperture) ∞ 7.94 10.31 13 20.503 3.02 1.56724 64.1 11.12 14 -21.985 0.74 11.40 15 -16.908 1.00 1.90043 37.4 11.36 16 58.603 4.42 1.49700 81.5 12.04 17 -15.011 (variable) 13.17 18 -23.876 1.10 1.85000 35.0 14.06 19 -82.849 (variable) 14.82 20* 112.899 3.87 1.49967 65.6 21.29 21* -32.833 2.02 22.35 22 -40.113 1.50 1.75377 52.3 23.28 23 -87.118 (variable) 24.42 Image plane ∞ Aspherical data Page 20 K = 0.00000e+000 A 4= 8.69555e-006 A 6=-1.43147e-007 A 8= 1.23812e-009 A10=-8.16964e-012 Page 21 K = 0.00000e+000 A 4= 4.80363e-005 A 6=-4.52567e-008 A 8= 1.32395e-009 A10=-7.40260e-012 Various data Zoom ratio 1.87 Wide-angle, Medium, Telephoto Focal length 15.60 19.00 29.15 F-numbers: 4.54, 4.86, 5.73 Half-angle (°): 49.09, 44.98, 35.72 Image height 18.00 18.99 20.96 Lens length: 120.00 x 112.82 x 104.38 BF 18.33 24.39 34.47 d 8 30.79 19.62 1.20 d17 2.82 2.53 3.93 d19 10.38 8.60 7.10 d23 18.33 24.39 34.47 Entrance pupil position 17.79 16.60 13.71 Exit pupil position -40.00 -36.67 -35.07 Front principal point position 29.21 29.69 30.64 Back principal point position 2.73 5.39 5.32 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -27.61 25.54 -1.42 -26.70 2 9 25.57 23.66 12.00 -11.67 3 18 -39.80 1.10 -0.24 -0.84 4 20 101.68 7.39 0.11 -5.31 Single lens data Lens starting plane, focal length 1 1 -32.78 2 3 -37.19 3 5 -39.21 4 7 27.44 5 9 -48.51 6 10 24.15 7 13 19.20 8 15 -14.48 9 16 24.53 10 18 -39.80 11 20 51.36 12 22 -100.00 The following table shows various values ​​for each example.

[0058] [Table 1]

[0059] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention will be described with reference to Figure 13. In Figure 13, 10 is the camera body, and 11 is a lens device including one of the zoom lenses L0 described in Examples 1 to 6.

[0060] 12 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body and receives the optical image formed by the lens device 11 and converts it into photoelectric energy. The camera body 10 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0061] Thus, by applying the zoom lens L0 of the present invention to an imaging device such as a digital still camera, high-quality images with low aberrations and reduced ghosting can be obtained.

[0062] Although preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of its gist. [Explanation of Symbols]

[0063] L0 Zoom Lens L1 First lens group L2 Second lens group L3 Third lens group L4 4th lens group L5 5th lens group L6 6th lens group

Claims

1. In a zoom lens having a first lens group with negative refractive power, a second lens group with positive refractive power, and two or more lens groups arranged sequentially from the object side to the image side, the first lens group moves during zooming, and the spacing between adjacent lens groups changes, The first lens group consists of three negative lenses and a positive lens positioned on the image side of the three negative lenses. The refractive index of negative lens A, which is positioned closest to the object among the negative lenses included in the first lens group, is 1.89 or higher. When Ra is the radius of curvature of the image-side lens surface of the negative lens A, Rb is the radius of curvature of the object-side lens surface of lens B, which is positioned adjacent to the image-side of the negative lens A, Da is the air gap between the negative lens A and lens B, and Db is the air gap between lens B and the lens positioned adjacent to the image-side of lens B, 2.0<Ra / Da<100 10<Rb / Db<100 A zoom lens characterized by satisfying the following conditional equation.

2. When the refractive index of lens B is NdB, 1.80 < NdB The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. Having an opening diaphragm, When d is the distance from the image-side lens surface of the negative lens A to the aperture diaphragm at the wide-angle end, and fw is the focal length of the zoom lens at the wide-angle end, 2.0<d / fw<15 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. Having an opening diaphragm, When d2 is the distance from the image-side lens surface of lens B to the aperture diaphragm at the wide-angle end, and fw is the focal length of the zoom lens at the wide-angle end, 1.5<d2 / fw<5.0 A zoom lens according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When GL is the distance from the lens surface closest to the object to the lens surface closest to the image in the first lens group, and TL is the distance from the lens surface closest to the object to the image plane in the zoom lens at the wide-angle end, 0.15<GL / TL<0.30 A zoom lens according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. When y is the maximum real image height at the wide-angle end, and y0 is the ideal image height of the maximum angle of view of the zoom lens at the wide-angle end, -20<100×(y-y0) / y0<-8 A zoom lens according to any one of claims 1 to 5, characterized in that it satisfies the following conditional expression.

7. When the focal length of the first lens group is f1 and the focal length of the zoom lens at the wide-angle end is fw, -2.5<f1 / fw<-0.8 A zoom lens according to any one of claims 1 to 6, characterized in that it satisfies the following conditional expression.

8. When the focal length of the negative lens A is fa and the focal length of the zoom lens at the wide-angle end is fw, -3.5<fa / fw<-1.5 A zoom lens according to any one of claims 1 to 7, characterized in that it satisfies the following conditional expression.

9. The zoom lens according to any one of claims 1 to 8, characterized in that lens B is a negative lens.

10. When the focal length of lens B is fb and the focal length of the zoom lens at the wide-angle end is fw, -3.5<fb / fw<-0.8 The zoom lens according to claim 9, characterized in that it satisfies the following condition.

11. When the focal length of the zoom lens at the telephoto end is ft and the focal length of the zoom lens at the wide-angle end is fw, 1.2<ft / fw<2.1 A zoom lens according to any one of claims 1 to 10, characterized in that it satisfies the following conditional expression.

12. The zoom lens according to any one of claims 1 to 11, characterized in that the zoom lens has a lens group with positive refractive power closest to the image side.

13. The zoom lens according to any one of claims 1 to 11, characterized in that the zoom lens has a lens group with negative refractive power closest to the image side.

14. An imaging device characterized by having a zoom lens according to any one of claims 1 to 13 and an image sensor that receives an image formed by the zoom lens.

Images