Zoom lens and imaging device, imaging system having the same

Abstract

To provide a lightweight zoom lens with high optical performance across the entire zoom range, and an imaging device or system having the same. [Solution] The zoom lens has a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including multiple lens groups, arranged sequentially from the object side to the image side. When zooming, the first lens group remains stationary, while the second lens group moves. The first lens group consists of a first subgroup and a second subgroup, arranged sequentially from the object side to the image side. The first subgroup consists of two positive lenses, and the second subgroup consists of one positive lens and one negative lens. The focal lengths of the first subgroup, the second subgroup, the first lens group, and the second lens group are set appropriately.

Description

Technical Field

[0001] The present invention relates to a zoom lens, and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver salt film cameras, surveillance cameras, etc.

Background Art

[0002] In recent years, zoom lenses used in imaging devices are required to be lightweight while having high optical performance over the entire zoom range. In order to meet these requirements, a zoom lens has been proposed that has a first lens group with a positive refractive power, a second lens group with a negative refractive power, and a subsequent group including a plurality of lens groups, which are arranged in order from the object side to the image side (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] For a large-aperture telephoto zoom lens with a long focal length and a small F-number, the lens diameter tends to be large and the weight tends to increase. In order to achieve weight reduction of the zoom lens, it is effective to increase the positive refractive power of the first lens group and reduce the lens diameter of the lens groups included in the subsequent group. However, if the refractive power of the first lens group is increased too much, it becomes difficult to correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration, especially at the telephoto end.

[0005] An object of the present invention is to provide a zoom lens having high optical performance over the entire zoom range, a lightweight zoom lens, an imaging device having the same, and an imaging system.

Means for Solving the Problems

[0006] A zoom lens as one aspect of the present invention has a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including multiple lens groups, arranged sequentially from the object side to the image side. During zooming, the first lens group remains stationary, while the second lens group moves. The first lens group consists of a first subgroup and a second subgroup, arranged sequentially from the object side to the image side. The first subgroup consists of two positive lenses, and the second subgroup consists of one positive lens and one negative lens. When the focal length of the first subgroup is f1a, the focal length of the second subgroup is f1b, the focal length of the first lens group is f1, and the focal length of the second lens group is f2, -0.45 <f1a / f1b<-0.10 -5.50 <f1 / f2<-3.00 It is characterized by satisfying the following conditional expression. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a lightweight zoom lens with high optical performance across the entire zoom range, as well as an imaging device and imaging system having the same. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view of the zoom lens of Example 1 at its wide-angle end. [Figure 2] (A), (B), and (C) are aberration diagrams of the wide-angle end, intermediate zoom position, and telephoto end of Example 1. [Figure 3] This is a cross-sectional view of the zoom lens of Example 2 at its wide-angle end. [Figure 4] (A), (B), and (C) are aberration diagrams of the wide-angle end, intermediate zoom position, and telephoto end of Example 2. [Figure 5] This is a cross-sectional view of the zoom lens of Example 3 at its wide-angle end. [Figure 6] (A), (B), and (C) are aberration diagrams of the wide-angle end, intermediate zoom position, and telephoto end of Example 3. [Figure 7]This is a cross-sectional view of the zoom lens of Example 4 at its wide-angle end. [Figure 8] (A), (B), and (C) are aberration diagrams of the wide-angle end, intermediate zoom position, and telephoto end of Example 4. [Figure 9] This is a schematic diagram of the imaging device. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same reference numeral is used for identical components, and redundant descriptions are omitted.

[0010] Figures 1, 3, 5, and 7 are cross-sectional views of the zoom lenses of Examples 1 to 4 at their wide-angle ends, respectively. The zoom lenses of each example are used in imaging devices and optical equipment, including interchangeable lenses, such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras.

[0011] In each cross-sectional view, the left side is the object side and the right side is the image side. The zoom lens of each embodiment is composed of multiple lens groups. In this specification, a lens group is a collection of lenses that move or remain stationary as a whole during zooming. That is, in the zoom lens of each embodiment, the distance between adjacent lens groups changes during zooming. A lens group may consist of one lens or multiple lenses. Furthermore, a lens group may include an aperture diaphragm.

[0012] The zoom lens of each embodiment has a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, and a subsequent group comprising multiple lens groups, arranged in order from the object side to the image side.

[0013] In each cross-sectional view, Li represents the i-th lens group (where i is a natural number) from the object side among the lens groups included in the zoom lens.

[0014] Also, the SP is an aperture stop. The IP is an image plane. When the zoom lens of each embodiment is used as the imaging optical system of a digital still camera or a digital video camera, the imaging surface of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed at the image plane. When the zoom lens of each embodiment is used as the imaging optical system of a camera for silver halide film, a photosensitive surface corresponding to the film surface is placed at the image plane IP.

[0015] In the zoom lens of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group is moved in the direction of the solid arrow. Also, in the zoom lens of each embodiment, when focusing from an infinite object to a close object, each lens group is moved in the direction of the dotted arrow.

[0016] Further, in the zoom lens of each embodiment, by moving a lens group having a positive refractive power or a part of the lens group disposed on the image side of the aperture stop SP in a direction including a component in a direction orthogonal to the optical axis, the optical image on the image plane can be displaced. By utilizing this, when vibration such as camera shake is applied to the zoom lens used as the imaging optical system, image blur on the image plane can be corrected.

[0017] FIGS. 2(A), 4(A), 6(A), and 8(A) are aberration diagrams at the wide-angle ends of the zoom lenses of Embodiments 1 to 4, respectively. FIGS. 2(B), 4(B), 6(B), and 8(B) are aberration diagrams at the intermediate zoom positions of the zoom lenses of Embodiments 1 to 4, respectively. FIGS. 2(C), 4(C), 6(C), and 8(C) are aberration diagrams at the telephoto ends of the zoom lenses of Embodiments 1 to 4, respectively.

[0018] In the spherical aberration diagram, Fno is the F-number, and it shows the amount of spherical aberration with respect to the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS shows the amount of astigmatism at the sagittal image plane, and ΔM shows the amount of astigmatism at the meridional image plane. The distortion aberration diagram shows the amount of distortion aberration with respect to the d-line. The chromatic aberration diagram shows the amount of chromatic aberration at the g-line. ω is the imaging semi-angle (degrees).

[0019] Next, we will describe the characteristic configurations of the zoom lenses in each embodiment.

[0020] During zooming, the first lens group L1 remains stationary, while the second lens group L2 moves.

[0021] The first lens group L1 consists of a first subgroup 1a and a second subgroup 1b, which are arranged in order from the object side to the image side.

[0022] The first subgroup 1a consists of two positive lenses. The first subgroup 1a, which is positioned closest to the object, needs to appropriately converge the axial light beam at the telephoto end in order to reduce the lens diameter of the lens groups positioned closer to the image than the first subgroup 1a. In this case, the first subgroup 1a needs to have a strong positive refractive power, but it is difficult to reduce various aberrations such as spherical aberration and axial chromatic aberration at the telephoto end with a single positive lens, so multiple lenses are required. However, if the number of lenses in the first subgroup 1a is three or more, the aforementioned aberrations can be suppressed, but the first subgroup 1a becomes heavy, which is undesirable. In order to achieve convergence of the axial light beam, suppression of various aberrations, and weight reduction of the first subgroup 1a, it is preferable to construct the first subgroup 1a with two positive lenses.

[0023] The second subgroup 1b consists of one positive lens and one negative lens. It is preferable that the second subgroup 1b has a negative lens in order to effectively correct the aberrations generated in the first subgroup 1a. In order to effectively correct the aberrations without impairing the axial light beam convergence effect of the first subgroup 1a, it is preferable that the second subgroup 1b has a weak negative refractive power. In order to satisfy these conditions while achieving weight reduction of the second subgroup 1b, it is preferable that the second subgroup 1b is composed of one positive lens and one negative lens.

[0024] The zoom lens in each embodiment satisfies the following conditions (1) and (2).

[0025] -0.45 <f1a / f1b<-0.10 (1) -5.50 <f1 / f2<-3.00 (2) Here, f1a is the focal length of the first subgroup 1a. f1b is the focal length of the second subgroup 1b. f1 is the focal length of the first lens group L1. f2 is the focal length of the second lens group L2.

[0026] Conditional equation (1) specifies the ratio of the focal length of the first subgroup 1a to the focal length of the second subgroup 1b in order to reduce the weight of the second subgroup 1b and to adequately correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end. If the focal length of the first subgroup 1a becomes longer than the lower limit of conditional equation (1), the axial light beam incident on the second subgroup 1b cannot be sufficiently focused, the lens diameter of the second subgroup 1b will increase, and it will be difficult to reduce the weight of the second subgroup 1b, which is undesirable. If the focal length of the first subgroup 1a becomes shorter than the upper limit of conditional equation (1), it will be difficult to correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end, which is also undesirable.

[0027] Conditional equation (2) specifies the ratio of the focal length of the first lens group L1 to the focal length of the second lens group L2 in order to achieve both lightweight design and high optical performance in the zoom lens. If the focal length of the first lens group L1 becomes longer than the lower limit of conditional equation (2), the lens diameter of the second lens group L2 and subsequent lens groups, which are positioned closer to the image than the first lens group L1, becomes larger, making it difficult to lighten the zoom lens, which is undesirable. Also, if the focal length of the second lens group L2 becomes shorter than the lower limit of conditional equation (2), it becomes difficult to correct off-axis aberrations such as coma aberration and field curvature at the wide-angle end, which is undesirable. If the focal length of the first lens group L1 becomes shorter than the upper limit of conditional equation (2), it becomes difficult to correct axial chromatic aberration and lateral chromatic aberration at the telephoto end, which is undesirable. Furthermore, if the focal length of the second lens group L2 exceeds the upper limit of condition (2), the overall length of the zoom lens increases, resulting in a larger zoom lens, which is undesirable.

[0028] Furthermore, it is preferable that the numerical ranges of conditional expressions (1) and (2) be the same as the numerical ranges of conditional expressions (1a) and (2a) below.

[0029] -0.42 <f1a / f1b<-0.15 (1a) -4.80 <f1 / f2<-3.15 (2a) Furthermore, it is even more preferable to set the numerical ranges of conditional expressions (1) and (2) to the numerical ranges of the following conditional expressions (1b) and (2b).

[0030] -0.39 <f1a / f1b<-0.20 (1b) -4.00 <f1 / f2<-3.30 (2b) Next, we will describe the conditions that the zoom lens of each embodiment preferably satisfies. The zoom lens of each embodiment preferably satisfies one or more of the following conditional expressions (3) to (8).

[0031] 0.60 <f1 / ft<1.10 (3) 0.05 <D1ab / D1<0.25 (4) 0.50 <f12 / f11<1.00 (5) 0.20 <M2 / ft<0.35 (6) 75<νd1ave<100 (7) -0.90 <f2 / fw<-0.50 (8) Here, ft is the focal length of the zoom lens at the telephoto end. D1ab is the distance along the optical axis from the image-side lens surface of the first subgroup 1a to the object-side lens surface of the second subgroup 1b. D1 is the distance along the optical axis from the object-side lens surface of the first lens group L1 to the image-side lens surface of the first lens group L1. f11 is the focal length of the positive lens L11 located on the object side in the first subgroup 1a. f12 is the focal length of the positive lens L12 located on the image side in the first subgroup 1a. M2 is the amount of movement of the second lens group L2 when zooming from the wide-angle end to the telephoto end, with movement toward the image side being positive. νd1ave is the average value of the Abbe numbers on the d line of all positive lenses included in the first lens group L1. fw is the focal length of the zoom lens at the wide-angle end.

[0032] Conditional equation (3) specifies the ratio of the focal length of the first lens group L1 to the focal length of the zoom lens at the telephoto end in order to achieve both a reduction in the overall length of the zoom lens and correction of spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end. If the focal length of the first lens group L1 is shortened below the lower limit of conditional equation (3), it becomes difficult to correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end, which is undesirable. If the focal length of the first lens group L1 is lengthened above the upper limit of conditional equation (3), the overall length of the zoom lens increases, making the zoom lens larger, which is also undesirable.

[0033] Conditional equation (4) specifies the arrangement of the first subgroup 1a and the second subgroup 1b in order to achieve both weight reduction of the second subgroup 1b and correction of spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end. If the distance from the image-side lens surface of the first subgroup 1a to the object-side lens surface of the second subgroup 1b becomes shorter, below the lower limit of conditional equation (4), the axial light beam incident on the second subgroup 1b cannot be sufficiently focused. As a result, the lens diameter of the second subgroup 1b becomes larger, making it difficult to reduce the weight of the second subgroup 1b, which is undesirable. If the distance from the image-side lens surface of the first subgroup 1a to the object-side lens surface of the second subgroup 1b becomes longer, exceeding the upper limit of conditional equation (4), it becomes difficult to correct spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end, which is undesirable.

[0034] Conditional equation (5) specifies the ratio of the focal length of positive lens L11 to the focal length of positive lens L12 in order to adequately correct spherical aberration and axial chromatic aberration at the telephoto end. If the focal length of positive lens L12 becomes shorter than the lower limit of conditional equation (5), it becomes difficult to correct spherical aberration and axial chromatic aberration at the telephoto end, which is undesirable. If the focal length of positive lens L11 becomes shorter than the upper limit of conditional equation (5), it becomes difficult to correct spherical aberration and axial chromatic aberration at the telephoto end, which is also undesirable.

[0035] Conditional equation (6) specifies the ratio of the amount of movement of the second lens group L2 during zooming to the focal length of the zoom lens at the telephoto end, in order to shorten the overall length of the zoom lens and to correct axial chromatic aberration at the telephoto end. If the amount of movement of the second lens group L2 during zooming falls below the lower limit of conditional equation (6), the refractive power of the second lens group L2 becomes too strong in order to obtain a sufficient magnification ratio, making it difficult to correct axial chromatic aberration at the telephoto end, which is undesirable. If the amount of movement of the second lens group L2 during zooming exceeds the upper limit of conditional equation (6), the zoom lens becomes larger, which is also undesirable.

[0036] Conditional equation (7) specifies the average Abbe number on the d line of all positive lenses included in the first lens group L1 in order to effectively correct axial chromatic aberration and lateral chromatic aberration at the telephoto end. If the average Abbe number on the d line of all positive lenses included in the first lens group L1 falls below the lower limit of conditional equation (7), it becomes difficult to correct axial chromatic aberration and lateral chromatic aberration at the telephoto end, which is undesirable. If the average Abbe number on the d line of all positive lenses included in the first lens group L1 rises above the upper limit of conditional equation (7), axial chromatic aberration and lateral chromatic aberration at the telephoto end can be effectively corrected. However, with existing glass materials, the refractive index becomes too low, making it difficult to correct spherical aberration at the telephoto end, which is undesirable.

[0037] Conditional equation (8) specifies the ratio of the focal length of the second lens group L2 to the focal length of the zoom lens at the wide-angle end in order to achieve both weight reduction of the second lens group L2 and correction of off-axis aberrations such as coma aberration and field curvature at the wide-angle end. If the focal length of the second lens group L2 becomes longer than the lower limit of conditional equation (8), the lens diameter of the second lens group L2 becomes larger, making it difficult to reduce the weight of the second lens group L2, which is undesirable. If the focal length of the second lens group L2 becomes shorter than the upper limit of conditional equation (8), it becomes difficult to correct off-axis aberrations such as coma aberration and field curvature at the wide-angle end, which is also undesirable.

[0038] Furthermore, it is preferable that the numerical ranges of conditional expressions (3) to (8) be the numerical ranges of the following conditional expressions (3a) to (8a).

[0039] 0.70 <f1 / ft<1.00 (3a) 0.10 <D1ab / D1<0.23 (4a) 0.58 <f11 / f12<0.92 (5a) 0.23 <M2 / ft<0.32 (6a) 78<νd1ave<95 (7a) -0.82 <f2 / fw<-0.58 (8a) Furthermore, it is even more preferable to use the numerical ranges of the following conditional expressions (3) to (8) as the numerical ranges of the conditional expressions (3b) to (8b).

[0040] 0.80 <f1 / ft<0.96 (3b) 0.15 <D1ab / D1<0.21 (4b) 0.66 <f11 / f12<0.85 (5b) 0.25 <M2 / ft<0.30 (6b) 81<νd1ave<90 (7b) -0.75 <f2 / fw<-0.65 (8b) Next, we will describe the zoom lenses of each embodiment in detail.

[0041] The zoom lens of Example 1 is a 7-group zoom lens consisting of third lens groups L3 to seventh lens groups L7 with refractive powers of positive, positive, negative, negative, and positive, with the subsequent groups arranged sequentially from the object side to the image side. In the zoom lens of Example 1, when zooming from the wide-angle end to the telephoto end, the second lens group L2 moves toward the image side, the third lens group L3 moves toward the object side, the fifth lens group L5 moves toward the object side in a convex trajectory toward the image side, and the sixth lens group L6 moves toward the image side. The first lens group L1, the fourth lens group L4, and the seventh lens group L7 remain stationary during zooming. In the zoom lens of Example 1, focusing is performed by the movement of the fifth lens group L5 and the sixth lens group L6 along different trajectories. Specifically, when focusing from an object at infinity to an object at close range, the fifth lens group L5 and the sixth lens group L6 move toward the image side.

[0042] The zoom lens of Example 2 is a five-group zoom lens consisting of third lens groups L3 to fifth lens groups L5 with positive, negative, and positive refractive powers, with the subsequent groups arranged sequentially from the object side to the image side. In the zoom lens of Example 2, when zooming from the wide-angle end to the telephoto end, the second lens group L2 moves towards the image side and the fourth lens group L4 moves towards the object side. The first lens group L1, the third lens group L3, and the fifth lens group L5 remain stationary during zooming. In the zoom lens of Example 2, focusing is performed by the movement of the fourth lens group L4. Specifically, when focusing from an object at infinity to an object at close range, the fourth lens group L4 moves towards the image side.

[0043] The zoom lens of Example 3 is a 7-group zoom lens consisting of third lens groups L3 to seventh lens groups L7 with refractive powers of positive, negative, positive, negative, and positive, with the subsequent groups arranged sequentially from the object side to the image side. In the zoom lens of Example 3, when zooming from the wide-angle end to the telephoto end, the second lens group L2 moves toward the image side, the third lens group L3 and fourth lens group L4 move toward the object side, and the sixth lens group L6 moves toward the object side in a convex trajectory toward the image side. The first lens group L1, the fifth lens group L5, and the seventh lens group L7 remain stationary during zooming. In the zoom lens of Example 3, focusing is performed by the movement of the sixth lens group L6. Specifically, when focusing from an object at infinity to an object at close range, the sixth lens group L6 moves toward the image side.

[0044] The zoom lens of Example 4 is a 6-group zoom lens consisting of third lens groups L3 to sixth lens groups L6 with positive, negative, negative, and positive refractive powers, with the subsequent groups arranged sequentially from the object side to the image side. In the zoom lens of Example 4, when zooming from the wide-angle end to the telephoto end, the second lens group L2 moves toward the image side, the fourth lens group L4 moves toward the object side in a convex trajectory toward the image side, and the fifth lens group L5 moves toward the image side. The first lens group L1, the third lens group L3, and the sixth lens group L6 remain stationary during zooming. In the zoom lens of Example 4, focusing is performed by the movement of the fourth lens group L4 and the fifth lens group L5 along different trajectories. Specifically, when focusing from an object at infinity to an object at close range, the fourth lens group L4 and the fifth lens group L5 move toward the image side.

[0045] In the zoom lenses of each embodiment, the second lens group L2 consists of a negative lens, a negative lens, a positive lens, and a negative lens, arranged in order from the object side to the image side. With this configuration, sufficient negative refractive power can be obtained while effectively correcting coma aberration and field curvature at the wide-angle end, and thus the weight of the second lens group L2 can also be reduced.

[0046] In the zoom lens of each embodiment, the aperture diaphragm SP is located between the third lens group L3 and the fourth lens group L4, or within the third lens group L3.

[0047] Furthermore, during focusing, at least one lens group other than the fourth lens group L4 to the sixth lens group L6 may be moved.

[0048] 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 incident side. Also, 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, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0049] In each numerical example, d, focal length (mm), F-number, and half-angle of view (degrees) are all values ​​when the zoom lens of each example is focused on an object at infinity. "Back focus" is the distance along the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed in terms of air equivalent length. "Total lens length" is the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final surface of the zoom lens, plus the back focus.

[0050] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd 1 435.360 8.41 1.48749 70.2 2 -570.557 1.00 3 144.875 11.51 1.43875 94.7 4 3213.208 8.50 5 113.847 13.56 1.49700 81.5 6 -847.524 2.70 1.61340 44.3 7 107.418 (variable) 8 3163.839 2.00 1.59270 35.3 9 57.405 8.36 10 -101.612 1.80 1.49700 81.5 11 161.066 0.30 12 100.360 6.63 1.85478 24.8 13 -264.182 2.39 14 -115.832 1.80 1.69680 55.5 15 491.399 (variable) 16 249.103 5.99 1.49700 81.5 17 -128.650 0.50 18 129.745 9.76 1.49700 81.5 19 -74.540 2.00 1.67300 38.3 20 -1333.860 0.50 21 54.405 7.50 1.49700 81.5 22 433.835 (variable) 23 (aperture) ∞ 10.28 24 -148.769 1.60 1.51633 64.1 25 69.371 9.58 26 1901.045 4.10 1.85478 24.8 27 -96.905 2.00 28 5198.592 1.60 1.90366 31.3 29 59.212 3.83 30 70.488 1.80 1.80810 22.8 31 44.138 6.84 1.59282 68.6 32 -205.857 0.30 33 71.584 2.85 1.80400 46.5 34 163.001 1.50 35 41.273 2.29 1.83481 42.7 36 51.514 (variable) 37 224.893 3.05 1.80810 22.8 38 -149.874 1.50 1.77250 49.6 39 46.152 (Variable) 40 52.870 1.80 1.49700 81.5 41 37.091 (Variable) 42 90.301 9.64 1.58313 59.4 43* -88.102 9.39 44 -67.820 1.60 1.76182 26.5 45 -155.784 31.93 Image plane ∞ Aspherical data Page 43 K = 0.00000e+00 A 4=-1.36103e-06 A 6=-1.88328e-10 A 8= 1.14944e-13 A10 = -5.86480e-18 Various data Zoom ratio 2.83 Wide-angle, Medium, Telephoto Focal length 103.00 166.42 292.00 F-number 2.90 2.91 2.91 Half-angle (degrees): 11.86 7.41 4.24 Image height 21.64 21.64 21.64 Lens length 333.61 333.61 333.61 BF 31.93 31.93 31.93 d 7 6.68 43.95 81.22 d15 77.53 39.27 1.00 d22 2.93 3.93 4.93 d36 3.63 7.01 3.60 d39 8.11 5.49 9.73 d41 32.06 31.28 30.45 Zoom lens group data Group starting plane focal length 1 1 247.39 2 8 -69.85 3 16 65.43 4 23 136.41 5 37 -78.41 6 40 -259.90 7 42 133.85 First lens group Sub-lens group data Group starting plane focal length 1a 1 206.52 1b 5 -826.03 Single lens data Lens starting plane, focal length 1 1 507.94 2 3 345.40 3 5 202.89 4 6 -155.25 [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 357.911 9.12 1.48749 70.2 2 -634.182 1.00 3 150.018 11.39 1.43875 94.7 4 1917.212 8.00 5 152.149 8.96 1.43875 94.7 6 940.309 1.00 7 2744.842 3.80 1.65412 39.7 8 150.564 (variable) 9 136.590 2.00 1.59270 35.3 10 47.115 9.29 11 -133.963 1.80 1.49700 81.5 12 130.618 0.30 13 71.551 6.90 1.85478 24.8 14 3712.290 2.97 15 -121.136 1.80 1.76385 48.5 16 280.220 (variable) 17 126.302 5.43 1.53775 74.7 18 -382.910 0.50 19 78.163 6.65 1.49700 81.5 20 -1358.820 0.50 21 92.143 9.10 1.49700 81.5 22 -102.484 2.20 1.67300 38.3 23 491.679 5.15 24 (aperture) ∞ 3.90 25 -159.232 2.00 1.61340 44.3 26 148.675 8.20 27 -203.299 3.19 1.89286 20.4 28 -85.684 0.30 29 -657.804 1.50 1.80610 33.3 30 63.951 3.79 31 103.288 1.80 1.89286 20.4 32 54.282 6.49 1.69680 55.5 33 -312.910 0.30 34 88.252 3.45 1.85150 40.8 35 468.597 1.50 36 51.674 3.07 1.72916 54.7 37 87.793 (Variable) 38 342.082 3.41 1.89286 20.4 39 -96.736 1.50 1.85150 40.8 40 45.657 (variable) 41 -255.883 2.00 1.48749 70.2 42 57.060 6.57 43 113.451 4.43 1.71736 29.5 44 -1269.534 1.00 45 66.805 10.89 1.53775 74.7 46 -77.597 12.89 47 -143.456 2.00 1.92286 18.9 48 575.681 34.04 Image plane ∞ Various data Zoom ratio 2.83 Wide-angle, Medium, Telephoto Focal length 103.00 166.66 292.00 F number 2.91 2.91 2.91 Half-angle (degrees): 11.86 7.40 4.24 Image height 21.64 21.64 21.64 Lens length 350.00 350.00 350.00 BF 34.04 34.04 34.04 d 8 9.64 51.41 93.55 d16 84.91 43.14 1.00 d37 3.00 7.45 8.19 d40 36.36 31.91 31.17 Zoom lens group data Group starting plane focal length 1 1 279.79 2 9 -73.63 3 17 63.84 4 38 -64.60 5 41 171.50 First lens group Sub-lens group data Group starting plane focal length 1a 1 208.29 1b 5 -636.76 Single lens data Lens starting plane, focal length 1 1 470.74 2 3 370.22 3 5 412.29 4 7 -243.68 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 276.211 10.69 1.49700 81.5 2 -518.352 0.50 3 115.331 12.94 1.43875 94.7 4 972.244 10.00 5 2084.057 2.70 1.61340 44.3 6 97.100 1.00 7 103.768 10.69 1.48749 70.2 8 488.045 (variable) 9 165.489 2.00 1.59270 35.3 10 46.079 8.98 11 -129.707 1.80 1.49700 81.5 12 98.898 0.30 13 71.730 6.43 1.85478 24.8 14 1868.000 3.46 15 -98.768 1.80 1.72916 54.7 16 5343.346 (variable) 17 110.371 6.49 1.49700 81.5 18 -239.050 0.50 19 111.257 9.72 1.49700 81.5 20 -77.123 2.00 1.67003 47.2 21 -3139.749 0.50 22 56.291 7.77 1.49700 81.5 23 1259.545 2.61 24 (aperture) ∞ (variable) 25 -197.808 1.60 1.51633 64.1 26 88.977 5.71 27 -197.618 2.92 1.84666 23.8 28 -95.782 0.30 29 496.082 1.60 1.80100 35.0 30 48.826 (Variable) 31 69.734 1.80 1.80810 22.8 32 43.354 7.12 1.59282 68.6 33 -222.407 0.30 34 90.771 2.83 1.88300 40.8 35 276.166 1.50 36 39.982 2.69 1.75500 52.3 37 54.702 (Variable) 38 304.669 3.39 1.80810 22.8 39 -87.105 1.50 1.78590 44.2 40 41.289 (variable) 41 99.492 1.80 1.49700 81.5 42 49.560 15.59 43 68.599 11.00 1.58313 59.4 44* -86.039 13.62 45 -42.027 1.80 1.80518 25.4 46 -60.096 31.58 Image plane ∞ Aspherical data Page 44 K = 0.00000e+00 A 4=-1.63430e-06 A 6=-3.85253e-10 A 8= 1.42947e-13 A10 = -2.55937e-17 Various data Zoom ratio 2.83 Wide-angle, Medium, Telephoto Focal length 103.00 166.61 291.00 F number 2.91 2.91 2.91 Half-angle (degrees): 11.86 7.40 4.25 Image height 21.64 21.64 21.64 Lens length 331.70 331.70 331.70 BF 31.58 31.58 31.58 d 8 5.53 41.98 78.75 d16 77.22 39.38 1.20 d24 7.48 7.74 8.01 d30 3.71 4.84 5.97 d37 3.68 7.39 5.47 d40 22.55 18.84 20.76 Zoom lens group data Group starting plane focal length 1 1 242.51 2 9 -67.36 3 17 60.18 4 25 -51.69 5 31 47.95 6 38 -62.55 7 41 162.50 First lens group Sub-lens group data Group starting plane focal length 1a 1 164.54 1b 5 -432.99 Single lens data Lens starting plane, focal length 1 1 364.19 2 3 296.88 3 5 -166.12 4 7 267.90 [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 318.412 9.60 1.48749 70.2 2 -861.108 0.50 3 150.245 12.24 1.43387 95.1 4 9401.300 7.00 5 111.079 14.21 1.49700 81.5 6 -1731.157 0.20 7 -1429.819 2.40 1.61340 44.3 8 100.324 (variable) 9 -6502.891 1.80 1.58144 40.8 10 58.931 7.68 11 -110.449 1.60 1.49700 81.5 12 198.706 0.30 13 101.587 5.82 1.85478 24.8 14 -370.711 1.60 15 -131.451 1.60 1.76385 48.5 16 885.349 (variable) 17 139.669 5.94 1.49700 81.5 18 -250.111 0.50 19 79.286 9.55 1.49700 81.5 20 -110.681 1.80 1.78590 44.2 21 168.957 0.50 22 67.931 6.88 1.49700 81.5 23 8851.483 3.89 24 (aperture) ∞ 17.94 25 18059.683 4.63 1.84666 23.8 26 -78.373 1.50 1.72342 38.0 27 50.231 3.73 28 86.093 1.50 1.89286 20.4 29 49.267 6.22 1.72916 54.7 30 -265.136 0.30 31 77.830 2.83 1.80400 46.5 32 190.511 1.50 33 38.860 2.83 1.65160 58.5 34 55.133 (Variable) 35 334.840 2.79 1.89286 20.4 36 -158.150 1.50 1.77250 49.6 37 46.681 (Variable) 38 57.104 1.50 1.75500 52.3 39 39.022 (variable) 40 74.395 11.11 1.58313 59.4 41* -70.264 8.49 42 -46.660 1.40 1.64769 33.8 43 -141.783 35.45 Image plane ∞ Aspherical data Page 41 K = 0.00000e+00 A 4=-1.73775e-06 A 6= 1.43818e-10 A 8=-1.24546e-12 A10= 1.73713e-15 A12=-5.94146e-19 Various data Zoom ratio 2.86 Wide-angle, Medium, Telephoto Focal length 103.00 167.33 295.00 F-number 2.90 2.91 2.91 Half-angle (degrees): 11.86 7.37 4.19 Image height 21.64 21.64 21.64 Lens length 328.58 328.58 328.58 BF 35.45 35.45 35.45 d 8 5.83 46.30 87.14 d16 82.31 41.84 1.00 d34 6.72 9.37 4.67 d37 5.01 4.20 9.54 d39 27.90 26.05 25.41 Zoom lens group data Group starting plane focal length 1 1 256.11 2 9 -75.32 3 17 64.55 4 35 -76.86 5 38 -169.27 6 40 123.41 First lens group Sub-lens group data Group starting plane focal length 1a 1 203.91 1b 5 -680.08 Single lens data Lens starting plane, focal length 1 1 478.12 2 3 351.77 3 5 210.56 4 7 -152.74 The various values ​​in each numerical example are summarized in Table 1 below.

[0051] [Table 1]

[0052] [Imaging device] Next, an example of a digital still camera (imaging device) using the zoom lens of each embodiment as the imaging optical system will be described with reference to Figure 9. In Figure 9, 10 is the camera body, and 11 is the imaging optical system composed of any of the zoom lenses described in Examples 1 to 4. 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 imaging optical system 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.

[0053] By applying the zoom lenses of each embodiment to imaging devices such as digital still cameras, it is possible to obtain imaging devices with compact lenses. [Imaging System] Furthermore, an imaging system (surveillance camera system) may be configured that includes the zoom lens of each embodiment and a control unit that controls the zoom lens. In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming, focusing, and image blur correction. At this time, the control unit does not need to be integrated with the zoom lens; the control unit may be configured separately from the zoom lens. For example, a control unit (control device) located far away from the drive unit that drives each lens of the zoom lens may be configured to include a transmission unit that sends control signals (commands) for controlling the zoom lens. With such a control unit, the zoom lens can be remotely operated.

[0054] Alternatively, the control unit may be equipped with an operating section such as a controller or buttons for remotely operating the zoom lens, thereby enabling a configuration that controls the zoom lens in response to user input to the operating section. For example, the operating section may include a zoom-in button and a zoom-out button. In this case, the control unit should be configured to send a signal to the zoom lens drive unit so that when the user presses the zoom-in button, the magnification of the zoom lens increases, and when the user presses the zoom-out button, the magnification of the zoom lens decreases.

[0055] Furthermore, the imaging system may have a display unit, such as an LCD panel, that displays information (movement status) related to the zoom of the zoom lens. This information could include, for example, the zoom magnification (zoom status) or the amount of movement of each lens group (movement status). In this case, the user can remotely operate the zoom lens via the control unit while viewing the zoom information displayed on the display unit. The display unit and the control unit may be integrated by, for example, using a touch panel.

[0056] 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]

[0057] L1 First lens group L2 Second lens group 1a 1st subgroup 1b second subgroup

Claims

1. The system has a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group containing multiple lens groups, arranged sequentially from the object side to the image side. During zooming, the first lens group remains stationary, while the second lens group moves. The aforementioned first lens group consists of a first subgroup and a second subgroup arranged in order from the object side to the image side. The first subgroup consists of two positive lenses, The second subgroup consists of one positive lens and one negative lens. When the focal length of the first subgroup is f1a, the focal length of the second subgroup is f1b, the focal length of the first lens group is f1, and the focal length of the second lens group is f2, -0.45<f1a / f1b<-0.10 -5.50<f1 / f2<-3.00 A zoom lens characterized by satisfying the following conditional equation.

2. When the focal length of the zoom lens at the telephoto end is ft, 0.60<f1 / ft<1.10 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. When D1ab is the distance along the optical axis from the image-side lens surface of the first subgroup to the object-side lens surface of the second subgroup, and D1 is the distance along the optical axis from the object-side lens surface of the first lens group to the image-side lens surface of the first lens group, 0.05<D1ab / D1<0.25 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. In the first subgroup, when the focal length of the positive lens positioned on the object side is f11 and the focal length of the positive lens positioned on the image side is f12, 0.50<f12 / f11<1.00 A zoom lens according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When movement toward the image side is considered positive, and the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end is denoted as M2, 0.20<M2 / ft<0.35 A zoom lens according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. When νd1ave is the average value of the Abbe numbers on the d line of all positive lenses included in the first lens group, 75<νd1ave<100 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 zoom lens at the wide-angle end is fw, -0.90<f2 / fw<-0.50 A zoom lens according to any one of claims 1 to 6, characterized in that it satisfies the following conditional expression.

8. The subsequent group includes an aperture diaphragm and a group of lenses with positive refractive power positioned on the image side of the aperture diaphragm. The zoom lens according to any one of claims 1 to 7, characterized in that the group of lenses with positive refractive power or a part of the group of lenses moves in a direction that includes a component perpendicular to the optical axis when correcting image blur.

9. The zoom lens according to any one of claims 1 to 8, characterized in that the subsequent group consists of a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, arranged in order from the object side to the image side.

10. The zoom lens according to any one of claims 1 to 8, characterized in that the subsequent group consists of a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a fifth lens group with positive refractive power, arranged in order from the object side to the image side.

11. The zoom lens according to any one of claims 1 to 8, characterized in that the subsequent group consists of a third lens group with positive refractive power, a fourth lens group with negative refractive power, a fifth lens group with positive refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, arranged in order from the object side to the image side.

12. The zoom lens according to any one of claims 1 to 8, characterized in that the subsequent group consists of a third lens group with positive refractive power, a fourth lens group with negative refractive power, a fifth lens group with negative refractive power, and a sixth lens group with positive refractive power, arranged in order from the object side to the image side.

13. The zoom lens according to any one of claims 1 to 8, characterized in that the second lens group consists of a negative lens, a negative lens, a positive lens, and a negative lens arranged in order from the object side to the image side.

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

15. An imaging system characterized by comprising a zoom lens according to any one of claims 1 to 13, and a control unit that controls the zoom lens during zooming.

16. The imaging system according to claim 15, characterized in that the control unit is configured separately from the zoom lens and has a transmitting unit that transmits control signals for controlling the zoom lens.

17. The imaging system according to claim 15 or 16, characterized in that the control unit is configured separately from the zoom lens and has an operating section for operating the zoom lens.

18. The imaging system according to any one of claims 15 to 17, characterized in that it has a display unit that displays information regarding the zoom of the zoom lens.

Images