Zoom lens, and imaging device and imaging system having the same

Abstract

To provide a light-weight zoom lens which offers high optical performance over an entire zoom range and an entire object distance.SOLUTION: A zoom lens provided herein comprises a first lens group having positive refractive power, a second lens group having negative refractive power, a succeeding lens group comprising multiple lens groups, arranged in order from the object side to the image side, and is configured such that a distance between the first lens group and the second lens group and a distance between the second lens group and the succeeding group change when zooming. The succeeding lens group consists of a front lens group having positive refractive power at the telephoto end, a first sub group having negative refractive power, a second sub group having negative refractive power, and a rear lens group, arranged in order from the object side to the image side. The first sub group and the second sub group move on different trajectories while focusing. A focal length of the first sub group, a focal length of the second sub group, and a focal length of the zoom lens at the telephoto end are each set appropriately.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens, which is suitable for digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, surveillance cameras, and the like. [Background technology]

[0002] In recent years, zoom lenses used in imaging devices have been required to have high optical performance over the entire object distance range, from infinity to the closest distance, while also being quiet during focusing. To meet these requirements, zoom lenses have been proposed that perform focusing by moving two lens groups along different trajectories (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-118127 [Patent Document 2] International Publication No. 2020 / 250672 Summary of the Invention [Problem to be solved by the invention]

[0004] In a large-aperture telephoto zoom lens with a long focal length and a small F-number, if the focus group is located near the aperture or closer to the object than the aperture, the lens diameter of the focus group will be large, making it difficult to reduce the weight. As a result, the load on the actuator that drives the focus group will increase, making it difficult to achieve quiet, high-speed focusing. In order to reduce the weight of the focus group, it is important to appropriately position the focus group and set the refractive power of the lens groups before and after it.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a lightweight zoom lens that has high optical performance over the entire zoom range and at all object distances. [Means for solving the problem]

[0006] A zoom lens according to one aspect of the present invention has, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a subsequent group including a plurality of lens groups, in which the distance between the first lens group and the second lens group and the distance between the second lens group and the subsequent group change during zooming, and the subsequent group comprises, arranged in order from the object side to the image side, a front lens group having positive refractive power at the telephoto end, a first subgroup having negative refractive power, a second subgroup having negative refractive power, and a rear lens group, In the subsequent lens group, the distance between the front lens group and the first subgroup, the distance between the first subgroup and the second subgroup, and the distance between the second subgroup and the rear lens group change during zooming. During focusing, the first and second subgroups move on different trajectories, with the focal length of the first subgroup being fn, the focal length of the second subgroup being fn2, and the focal length of the zoom lens at the telephoto end being ft. When focusing at infinity at the telephoto end, the distance on the optical axis from the lens surface of the first sub-group closest to the image to the lens surface of the second sub-group closest to the object is defined as Dn, and the distance on the optical axis from the lens surface of the second sub-group closest to the image to the lens surface of the rear lens group closest to the object is defined as Dn2. When -0.50 <fn / ft<-0.10 0.30 <fn / fn2<0.60 0.20 <Dn / Dn2<0.80 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a lightweight zoom lens that has high optical performance over the entire zoom range and at all object distances. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a zoom lens of Example 1 at the wide-angle end when the object distance is infinity. [Figure 2] 1A, 1B, and 1C are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, when the object distance is infinity. [Figure 3] 3A, 3B, and 3C are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the object distance is close. [Figure 4] FIG. 10 is a cross-sectional view of the zoom lens of Example 2 at the wide-angle end when the object distance is infinite. [Figure 5]10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, when the object distance is infinity. [Figure 6] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the object distance is close. [Figure 7] FIG. 10 is a cross-sectional view of the zoom lens of Example 3 at the wide-angle end when the object distance is infinity. [Figure 8] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, when the object distance is infinity. [Figure 9] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the object distance is close. [Figure 10] FIG. 10 is a cross-sectional view of the zoom lens of Example 4 at the wide-angle end when the object distance is infinite. [Figure 11] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, when the object distance is infinity. [Figure 12] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the object distance is close. [Figure 13] FIG. 1 is a schematic diagram of an imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0010] 1, 4, 7, and 10 are cross-sectional views of the zoom lenses of Examples 1 to 4 at the wide-angle end with the object distance at infinity. The zoom lenses of each Example are used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras, as well as optical instruments including interchangeable lenses.

[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 configured with multiple lens groups. In this specification, a lens group refers to a group of lenses that move or remain stationary as a unit during zooming. That is, in the zoom lens of each embodiment, the distance between adjacent lens groups changes during zooming. Note that a lens group may be configured with one lens or multiple lenses. The lens group may also include an aperture stop.

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

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

[0014] Also, SP is an aperture stop. The aperture stop SP is located between the third lens group L3 and the fourth lens group L4, or within the third lens group L3. IP is an image plane, and when the zoom lens of each embodiment is used as the photographic optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is located thereon. When the zoom lens of each embodiment is used as the photographic optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is located at the image plane IP.

[0015] In the zoom lens of each embodiment, each lens group moves in the direction of the solid arrow when zooming from the wide-angle end to the telephoto end, and in the zoom lens of each embodiment, each lens group moves in the direction of the dotted arrow when focusing from infinity to the closest distance.

[0016] Furthermore, in the zoom lens of each embodiment, the optical image on the image plane can be displaced by moving a lens group with positive refractive power, or a part of the lens group, that is located closer to the image side than the aperture stop SP, in a direction that includes a component perpendicular to the optical axis. Utilizing this, image blur on the image plane can be corrected when vibrations such as camera shake are applied to a zoom lens used as a photographic optical system.

[0017] Figures 2(A), 5(A), 8(A), and 11(A) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the wide-angle end when the object distance is infinite. Figures 2(B), 5(B), 8(B), and 11(B) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the intermediate zoom positions when the object distance is infinite. Figures 2(C), 5(C), 8(C), and 11(C) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the telephoto end when the object distance is infinite.

[0018] Figures 3(A), 6(A), 9(A), and 12(A) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the wide-angle end and at close object distances, respectively. Figures 3(B), 6(B), 9(B), and 12(B) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the intermediate zoom positions and at close object distances, respectively. Figures 3(C), 6(C), 9(C), and 12(C) are aberration diagrams of the zoom lenses of Examples 1 to 4 at the telephoto end and at close object distances, respectively.

[0019] In the spherical aberration diagram, Fno is the F-number, and shows the amount of spherical aberration for the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS shows the amount of astigmatism on the sagittal image plane, and ΔM shows the amount of astigmatism on 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 for the g-line is shown. ω is the half angle of view (degrees).

[0020] Next, the characteristic configuration of the zoom lens of each embodiment will be described.

[0021] During zooming, the distance between the first lens unit L1 and the second lens unit L2 and the distance between the second lens unit L2 and the subsequent lens unit change.

[0022] The subsequent lens group consists of, arranged in order from the object side to the image side, a front lens group La with positive refractive power, an Ln group (first subgroup) with negative refractive power, an Ln2 group (second subgroup) with negative refractive power, and a rear lens group Lb. The front lens group La, which is arranged adjacent to the Ln group on the object side, has positive refractive power and sufficiently converges the axial light beam entering the Ln group, allowing the outer diameter of the Ln group to be reduced and the weight of the Ln group to be reduced.

[0023] During focusing, the Ln and Ln2 lens groups move along different paths. Specifically, throughout the entire zoom range, during focusing from infinity to the closest distance, the Ln and Ln2 lens groups move toward the image. Note that during focusing, at least one lens group other than the Ln and Ln2 lens groups may also move.

[0024] The zoom lens of each embodiment satisfies the following conditional expressions (1) and (2).

[0025] -0.50 <fn / ft<-0.10 (1) 0.30 <fn / fn2<0.60 (2) Here, fn is the focal length of the Ln group, fn2 is the focal length of the Ln2 group, and ft is the focal length of the zoom lens at the telephoto end.

[0026] Conditional expression (1) specifies the value of the ratio of the focal length of the Ln group to the focal length of the zoom lens at the telephoto end in order to achieve high performance at all object distances from infinity to the closest distance at the telephoto end. If the ratio falls below the lower limit of conditional expression (1) and the focal length of the Ln group becomes longer than the focal length of the zoom lens at the telephoto end, it becomes difficult to sufficiently correct coma aberration, field curvature, and the like at the telephoto end, which is undesirable. If the ratio exceeds the upper limit of conditional expression (1) and the focal length of the Ln group becomes shorter than the focal length of the zoom lens at the telephoto end, it becomes undesirable because aberration fluctuations that occur during focusing become too large.

[0027] Conditional expression (2) defines the ratio of the focal length of the Ln group to the focal length of the Ln2 group in order to achieve both compactness and high performance in a zoom lens. If the focal length of the Ln group becomes shorter below the lower limit of conditional expression (2), the fluctuations in aberrations that occur during focusing become too large, which is undesirable. Also, if the focal length of the Ln2 group becomes longer below the lower limit of conditional expression (2), it becomes difficult for the Ln2 group to adequately correct the fluctuations in aberrations that occur during focusing, which is undesirable. If the focal length of the Ln group becomes longer above the upper limit of conditional expression (2), the amount of movement of the Ln group during focusing becomes large, which is undesirable, as the zoom lens becomes larger.

[0028] It is preferable that the numerical ranges of the conditional expressions (1) and (2) be set to the numerical ranges of the following conditional expressions (1a) and (2a).

[0029] -0.40 <fn / ft<-0.15 (1a) 0.31 <fn / fn2<0.55 (2a) It is more preferable that the numerical ranges of the conditional expressions (1) and (2) be set to the numerical ranges of the following conditional expressions (1b) and (2b).

[0030] -0.30 <fn / ft<-0.20 (1b) 0.32 <fn / fn2<0.50 (2b) Next, the configurations that are preferably satisfied in the zoom lens of each embodiment will be described.

[0031] It is preferable that the rear lens group Lb has positive refractive power. By having the rear lens group Lb, which is arranged closest to the image side of the zoom lens, have positive refractive power, telecentricity on the image side can be ensured even when the Ln group has a strong negative refractive power, and off-axis aberrations can be corrected well, which is advantageous for making the Ln group smaller.

[0032] The first lens group L1 is preferably composed of three positive lenses and one negative lens, or two positive lenses and one negative lens. This configuration provides strong positive refractive power while effectively correcting spherical aberration, axial chromatic aberration, and lateral chromatic aberration at the telephoto end, allowing the lens diameters of the lens groups located closer to the image side than the first lens group L1 to be reduced.

[0033] The second lens group L2 preferably includes, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens. This configuration makes it possible to obtain sufficient negative refractive power while effectively correcting coma and field curvature at the wide-angle end, thereby achieving a reduction in the weight of the second lens group L2.

[0034] It is preferable that the Ln group be configured with a cemented lens element consisting of a positive lens element and a negative lens element, arranged in that order from the object side to the image side. This configuration makes it possible to effectively suppress aberration fluctuations that occur during focusing while also reducing the weight of the Ln group.

[0035] The Ln2 group is preferably configured with a negative meniscus lens with a convex shape facing the object side. This configuration minimizes the mass of the Ln2 group while suppressing fluctuations in off-axis aberrations such as field curvature that occur during focusing.

[0036] Next, conditions that the zoom lens of each embodiment should preferably satisfy will be described. The zoom lens of each embodiment should preferably satisfy one or more of the following conditional expressions (3) to (9).

[0037] -1.50 <fn / fa<-0.80 (3) -1.00 <fn / fb<-0.40 (4) 1.00 <Mn / Mn2<2.00 (5) 0.20 <Dn / Dn2<0.80 (6) 1.0<(R1+R2) / (R1-R2)<8.0 (7) 0.60 <f1 / ft<1.20 (8) -5.50 <f1 / f2<-3.00 (9) Here, fa is the focal length of the front lens group La at the telephoto end. fb is the focal length of the rear lens group Lb at the telephoto end. Mn, with movement toward the image side being positive, is the amount of movement of the Ln group during focusing from infinity to the closest distance at the telephoto end. Mn2, with movement toward the image side being positive, is the amount of movement of the Ln2 group during focusing from infinity to the closest distance at the telephoto end. Dn is the axial distance from the lens surface closest to the image in the Ln group to the lens surface closest to the object in the Ln2 group when focusing at infinity at the telephoto end. Dn2 is the axial distance from the lens surface closest to the image in the Ln2 group to the lens surface closest to the object in the rear lens group Lb when focusing at infinity at the telephoto end. The Ln2 group consists of a single negative lens, and R1 and R2 are the radii of curvature of the object-side and image-side lens surfaces of the negative lens, respectively. f1 is the focal length of the first lens group L1, and f2 is the focal length of the second lens group L2.

[0038] Conditional expression (3) specifies the value of the ratio of the focal length of the Ln group to the focal length of the front lens group La in order to achieve both a reduction in the weight of the Ln group and correction of spherical aberration, axial chromatic aberration, and the like throughout the entire zoom range. If the focal length of the front lens group La becomes short below the lower limit of conditional expression (3), it becomes difficult to correct spherical aberration, axial chromatic aberration, and the like throughout the entire zoom range, which is undesirable. If the focal length of the front lens group La becomes long above the upper limit of conditional expression (3), it becomes difficult to sufficiently converge the axial light beam, which is undesirable because the outer diameter of the Ln group becomes large.

[0039] Conditional expression (4) specifies the value of the ratio of the focal length of the rear lens group Lb to the focal length of the Ln group in order to ensure telecentricity on the image side throughout the entire zoom range while effectively correcting off-axial aberrations such as coma and field curvature. If the focal length of the rear lens group Lb becomes shorter than the lower limit of conditional expression (4), it becomes difficult to correct off-axial aberrations such as coma and field curvature throughout the entire zoom range, which is undesirable. If the focal length of the rear lens group Lb becomes longer than the upper limit of conditional expression (4), it becomes difficult to ensure sufficient telecentricity on the image side throughout the entire zoom range, which is also undesirable.

[0040] Conditional expression (5) defines the ratio of the amount of movement of the Ln group to the amount of movement of the Ln2 group during focusing, in order to achieve both a lightweight Ln2 group and suppression of aberration fluctuations during focusing at the telephoto end. If the amount of movement of the Ln group becomes small, falling below the lower limit of conditional expression (5), it becomes difficult to suppress aberration fluctuations during focusing while ensuring sufficient close-up magnification at the telephoto end, which is undesirable. If the amount of movement of the Ln group becomes large, exceeding the upper limit of conditional expression (5), it becomes necessary to increase the air gap between the Ln group and the Ln2 group when focusing at infinity at the telephoto end. In this case, the lens diameter of the Ln2 group becomes too large to ensure sufficient peripheral illumination at the telephoto end, which is undesirable.

[0041] Conditional expression (6) specifies the ratio of the air gap between the Ln group and the Ln2 group to the air gap between the Ln2 group and the rear lens group Lb when focusing at infinity at the telephoto end, in order to reduce the weight of the Ln2 group. If the air gap between the Ln group and the Ln2 group becomes small below the lower limit of conditional expression (6), the components holding the Ln group and the components holding the Ln2 group are likely to interfere with each other, making component placement difficult, which is undesirable. If the air gap between the Ln group and the Ln2 group becomes large above the upper limit of conditional expression (6), the lens diameter of the Ln2 group becomes too large to ensure sufficient peripheral illumination at the telephoto end, which is undesirable.

[0042] Conditional expression (7) defines the shape of the negative lens included in the Ln2 group in order to suppress fluctuations in aberrations that occur during focusing throughout the entire zoom range. By having the negative lens included in the Ln2 group take a shape that satisfies the range of conditional expression (7), fluctuations in field curvature that occur during focusing can be effectively suppressed.

[0043] Conditional expression (8) specifies the value of the ratio of the focal length of the first lens unit 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 unit L1 becomes short below the lower limit of conditional expression (8), 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 unit L1 becomes long above the upper limit of conditional expression (8), the overall length of the zoom lens becomes long, which is undesirable because the zoom lens becomes large.

[0044] Conditional expression (9) specifies the value of 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 and high performance in a zoom lens. If the focal length of the first lens group L1 becomes longer below the lower limit of conditional expression (9), the lens diameter of the subsequent group positioned closer to the object than the second lens group L2 becomes larger, making it difficult to reduce the weight, which is undesirable. Also, if the focal length of the second lens group L2 becomes shorter below the lower limit of conditional expression (9), it becomes difficult to correct off-axial aberrations such as coma and field curvature at the wide-angle end, which is undesirable. If the focal length of the first lens group L1 becomes shorter above the upper limit of conditional expression (9), it becomes difficult to correct axial chromatic aberrations and chromatic aberrations of magnification at the telephoto end, which is undesirable. Furthermore, if the focal length of the second lens unit L2 becomes long beyond the upper limit of conditional expression (9), the overall length of the zoom lens becomes long, which is undesirable as it results in the zoom lens becoming large.

[0045] It is preferable that the numerical ranges of the conditional expressions (3) to (9) be set to the numerical ranges of the following conditional expressions (3a) to (9a).

[0046] -1.35 <fn / fa<-0.90 (3a) -0.90 <fn / fb<-0.50 (4a) 1.15 <Mn / Mn2<1.85 (5a) 0.25 <Dn / Dn2<0.70 (6a) 1.5<(R1+R2) / (R1-R2)<7.0 (7a) 0.70 <f1 / ft<1.10 (8a) -4.50 <f1 / f2<-3.10 (9a) It is more preferable that the numerical ranges of the conditional expressions (3) to (9) be the numerical ranges of the following conditional expressions (3b) to (9b).

[0047] -1.20 <fn / fa<-1.00 (3b) -0.85 <fn / fb<-0.60 (4b) 1.30 <Mn / Mn2<1.70 (5b) 0.30 <Dn / Dn2<0.60 (6b) 2.0<(R1+R2) / (R1-R2)<6.0 (7b) 0.80 <f1 / ft<1.00 (8b) -3.80 <f1 / f2<-3.25 (9b) Next, the zoom lens of each embodiment will be described in detail.

[0048] In the zoom lens of each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 remains stationary relative to the image plane IP, and the second lens unit L2 moves toward the image side.

[0049] The zoom lens of Example 1 is a seven-group zoom lens, with subsequent groups arranged in order from the object side to the image side, consisting of the third lens group L3 to the seventh lens group L7, each with positive, positive, negative, negative, and positive refractive powers. The front lens group La is composed of the third lens group L3 and the fourth lens group L4. The lens group Ln is composed of the fifth lens group L5. The lens group Ln2 is composed of the sixth lens group L6. The rear lens group Lb is composed of the seventh lens group L7. During zooming from the wide-angle end to the telephoto end, the third lens group L3 moves toward the object side, the fifth lens group L5 moves along a locus convex toward the image side, and the sixth lens group L6 moves toward the image side. The fourth lens group L4 and the seventh lens group L7 do not move with respect to the image plane IP during zooming.

[0050] The zoom lens of Example 2 is a seven-group zoom lens, with subsequent groups arranged in order from the object side to the image side, consisting of the third lens group L3 to the seventh lens group L7, each with positive, negative, negative, positive, and negative refractive powers. The front lens group La is composed of the third lens group L3. The lens group Ln is composed of the fourth lens group L4. The lens group Ln2 is composed of the fifth lens group L5. The rear lens group Lb is composed of the sixth lens group L6 and the seventh lens group L7. During zooming from the wide-angle end to the telephoto end, the fourth lens group L4 moves along a locus convex toward the image side, the fifth lens group L5 moves toward the image side, and the sixth lens group L6 moves toward the object side. The third lens group L3 and the seventh lens group L7 do not move with respect to the image plane IP during zooming.

[0051] The zoom lens of Example 3 is an eight-group zoom lens, with the subsequent groups arranged in order from the object side to the image side, consisting of the third lens group L3 to the eighth lens group L8, each with positive, negative, positive, negative, negative, and positive refractive powers. The front lens group La is composed of the third lens group L3, the fourth lens group L4, and the fifth lens group L5. The lens group Ln is composed of the sixth lens group L6. The lens group Ln2 is composed of the seventh lens group L7. The rear lens group Lb is composed of the eighth lens group L8. During zooming from the wide-angle end to the telephoto end, the third lens group L3 moves toward the object side, the fourth lens group L4 moves toward the object side, the sixth lens group L6 moves along a locus convex toward the image side, and the seventh lens group L7 moves toward the image side. The fifth lens group L5 and the eighth lens group L8 do not move with respect to the image plane IP during zooming.

[0052] The zoom lens of Example 4 is a six-group zoom lens, with subsequent groups arranged in order from the object side to the image side, consisting of the third lens group L3 to the sixth lens group L6, each having positive, negative, negative, and positive refractive powers. The front lens group La is made up of the third lens group L3. The lens group Ln is made up of the fourth lens group L4. The lens group Ln2 is made up of the fifth lens group L5. The rear lens group Lb is made up of the sixth lens group L6. During zooming from the wide-angle end to the telephoto end, the fourth lens group L4 moves along a locus convex toward the image side, and the fifth lens group L5 moves toward the image side. The third lens group L3 and the sixth lens group L6 do not move with respect to the image plane IP during zooming.

[0053] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element. Note that the Abbe number vd of a certain material is given by the following equation, where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines: νd=(Nd-1) / (NF-NC) It is expressed as:

[0054] 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 on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final lens surface, plus the back focus.

[0055] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 401.515 8.67 1.48749 70.2 2 -575.025 1.00 3 143.949 11.46 1.43875 94.7 4 2230.647 8.50 5 114.773 13.44 1.49700 81.5 6 -849.238 2.70 1.61340 44.3 7 106.615 (variable) 8 18647.337 2.00 1.59270 35.3 9 57.867 8.27 10 -102.826 1.80 1.49700 81.5 11 157.225 0.30 12 100.288 6.63 1.85478 24.8 13 -264.252 2.34 14 -116.543 1.80 1.69680 55.5 15 520.283 (variable) 16 270.542 5.95 1.49700 81.5 17 -125.289 0.50 18 125.166 9.91 1.49700 81.5 19 -73.921 2.00 1.67300 38.3 20 -1537.779 0.50 21 54.405 7.49 1.49700 81.5 22 433.835 (variable) 23 (Aperture) ∞ 10.28 24 -150.847 1.60 1.51633 64.1 25 68.329 9.84 26 1839.709 4.12 1.85478 24.8 27 -96.342 2.00 28 4059.007 1.60 1.90366 31.3 29 59.475 3.83 30 70.766 1.80 1.80810 22.8 31 44.422 6.81 1.59282 68.6 32 -209.751 0.30 33 73.334 2.77 1.80400 46.5 34 159.968 1.50 35 41.571 2.32 1.83481 42.7 36 52.463 (variable) 37 225.006 3.04 1.80810 22.8 38 -152.645 1.50 1.77250 49.6 39 47.142 (variable) 40 54.348 1.80 1.49700 81.5 41 37.362 (variable) 42 87.959 9.73 1.58313 59.4 43* -87.744 9.11 44 -69.537 1.60 1.76182 26.5 45 -170.847 32.73 Image plane ∞ Aspheric data Page 43 K = 0.00000e+00 A 4=-1.29285e-06 A 6=-1.67230e-10 A 8= 1.09836e-13 A10=-3.96015e-18 Various data Zoom ratio 2.83 Wide-angle Mid-range Telephoto Focal length 103.00 166.06 292.00 F-number 2.89 2.91 2.91 Half angle of view (degrees) 11.86 7.42 4.24 Image height 21.64 21.64 21.64 Lens total length 334.46 334.46 334.46 BF 32.73 32.73 32.73 Focusing at infinity d 7 6.76 43.99 81.55 d15 77.79 39.57 1.00 d22 2.69 3.68 4.69 d36 3.60 7.04 3.60 d39 8.09 5.61 10.02 d41 31.99 31.03 30.06 At close focus d 7 6.76 43.99 81.55 d15 77.79 39.57 1.00 d22 2.69 3.68 4.69 d36 5.26 12.79 21.63 d39 12.62 6.55 5.40 d41 25.80 24.34 16.65 Zoom lens group data Group starting plane focal length 1 1 248.67 2 8 -70.07 3 16 65.41 4 23 140.03 5 37 -80.57 6 40 -249.30 7 42 132.86 La 16 69.01 Lb 42 132.86 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 390.281 3.00 1.83481 42.7 2 156.026 13.45 1.49700 81.5 3 -855.331 0.30 4 153.285 12.38 1.43875 94.7 5 -1578.299 (variable) 6 68.592 10.50 1.56732 42.8 7 -713.396 0.30 8 573.492 1.80 1.69895 30.1 9 46.926 9.61 10 -203.994 1.80 1.49700 81.5 11 51.125 7.74 2.00100 29.1 12 246.853 4.70 13 -98.481 1.80 1.72916 54.7 14 152.138 (variable) 15 79.457 8.69 1.49700 81.5 16 -163.945 0.30 17 58.889 10.46 1.49700 81.5 18 -124.992 1.29 19 -86.830 2.20 1.88300 40.8 20 1541.718 2.18 21 (Aperture) ∞ 6.30 22 -108.016 3.59 1.80810 22.8 23 -65.830 7.62 24 -176.864 2.00 1.72047 34.7 25 51.368 5.45 26 261.511 3.02 1.80400 46.5 27 -305.004 0.20 28 77.093 6.99 1.72916 54.7 29 -63.815 1.80 1.85478 24.8 30 -269.965 1.50 31 42.982 2.30 2.00100 29.1 32 53.992 (variable) 33 358.651 3.06 1.89286 20.4 34 -102.709 1.50 1.83481 42.7 35 45.414 (variable) 36 112.183 2.00 1.49700 81.5 37 52.709 (variable) 38 100.708 2.00 1.72825 28.5 39 34.566 11.42 1.49700 81.5 40 1252.280 0.50 41 55.642 13.34 1.58144 40.8 42 -62.945 (variable) 43 -85.685 2.00 1.53775 74.7 44 96.756 36.86 Image plane ∞ Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 103.00 168.35 293.00 F-number 2.91 2.91 2.91 Half angle of view (degrees) 11.86 7.32 4.22 Image height 21.64 21.64 21.64 Lens total length 345.00 345.00 345.00 BF 36.86 36.86 36.86 Focusing at infinity d 5 3.14 48.80 94.87 d14 93.08 47.42 1.35 d32 4.00 7.00 4.00 d35 8.42 7.00 10.98 d37 25.30 23.11 21.52 d42 5.10 5.71 6.31 At close focus d 5 3.14 48.80 94.87 d14 93.08 47.42 1.35 d32 5.54 11.91 19.89 d35 10.95 7.49 4.64 d37 21.23 17.71 11.97 d42 5.10 5.71 6.31 Zoom lens group data Group starting plane focal length 1 1 271.61 2 6 -82.54 3 15 62.88 4 33 -65.75 5 36 -202.31 6 38 53.15 7 43 -84.18 La 15 62.88 Lb 38 103.16 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 184.878 11.07 1.49700 81.5 2 -3367.872 0.50 3 199.809 4.00 1.61340 44.3 4 89.882 15.63 1.43875 94.7 5 726.065 (variable) 6 67.923 10.00 1.80100 35.0 7 1481.720 0.30 8 428.681 1.80 1.67270 32.1 9 40.406 9.64 10 -890.132 1.80 1.49700 81.5 11 45.409 6.34 2.00100 29.1 12 100.862 6.75 13 -83.966 1.80 1.83481 42.7 14 745.930 (variable) 15 92.374 7.03 1.59282 68.6 16 -231.808 0.30 17 67.451 10.42 1.49700 81.5 18 -91.208 2.20 1.80400 46.5 19 519.346 5.18 20 (Aperture) ∞ (Variable) 21 -405.890 3.40 1.89286 20.4 22 -104.384 0.50 23 -213.126 2.00 1.90366 31.3 24 59.441 (variable) 25 79.928 1.80 1.85478 24.8 26 48.444 6.97 1.59282 68.6 27 -184.361 0.20 28 85.307 3.43 1.77250 49.6 29 722.459 1.50 30 44.321 2.95 1.83481 42.7 31 70.390 (variable) 32 506.530 3.04 1.89286 20.4 33 -131.334 1.50 1.80400 46.5 34 44.406 (variable) 35 162.579 2.00 1.65160 58.5 36 55.106 (variable) 37 134.810 2.00 1.87400 35.3 38 36.017 10.79 1.77250 49.6 39 237.668 1.00 40 69.854 11.40 1.61340 44.3 41 -66.276 10.64 42 -71.912 2.00 1.54814 45.8 43 389.691 37.47 Image plane ∞ Various data Zoom ratio 2.45 Wide-angle Mid-range Telephoto Focal length 120.00 183.94 294.00 F-number 2.91 2.91 2.91 Half angle of view (degrees) 10.22 6.71 4.21 Image height 21.64 21.64 21.64 Lens total length 350.00 350.00 350.00 BF 37.47 37.47 37.47 Focusing at infinity d 5 14.73 51.65 88.89 d14 80.67 41.19 1.36 d20 14.02 15.52 17.04 d24 3.34 4.41 5.48 d31 3.27 5.38 4.45 d34 10.25 9.35 10.50 d36 24.36 23.15 22.93 At close focus d 5 14.73 51.65 88.89 d14 80.67 41.19 1.36 d20 14.02 15.52 17.04 d24 3.34 4.41 5.48 d31 5.40 10.54 17.12 d34 9.86 7.00 7.40 d36 22.62 20.34 13.36 Zoom lens group data Group starting plane focal length 1 1 293.50 2 6 -83.04 3 15 84.36 4 21 -76.71 5 25 43.19 6 32 -64.18 7 35 -128.88 8 37 91.32 La 15 61.75 Lb 37 91.32 [Numerical Example 4] Unit: mm Surface Data Surface 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 ∞ Aspheric 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 Mid-range Telephoto Focal length 103.00 167.33 295.00 F-number 2.90 2.91 2.91 Half angle of view (degrees) 11.86 7.37 4.19 Image height 21.64 21.64 21.64 Lens total length 328.58 328.58 328.58 BF 35.45 35.45 35.45 Focusing at infinity 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 At close focus d 8 5.83 46.30 87.14 d16 82.31 41.84 1.00 d34 7.89 13.73 19.08 d37 8.60 6.18 5.62 d39 23.14 19.71 14.92 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 La 17 64.55 Lb 40 123.41 The various values ​​in each numerical example are summarized in Table 1 below.

[0056] [Table 1]

[0057] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of each embodiment as an imaging optical system will be described with reference to Fig. 13. In Fig. 13, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the zoom lenses described in Embodiments 1 to 4. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body and receives and photoelectrically converts an optical image formed by the imaging optical system 11. The camera body 10 may be a so-called single-lens reflex camera having a quick-turn mirror, or a so-called mirrorless camera having no quick-turn mirror.

[0058] In this way, by applying the zoom lens of each embodiment to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained. [Imaging system] 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 stabilization. In this case, the control unit does not need to be configured integrally with the zoom lens; the control unit may be configured separately from the zoom lens. For example, a control unit (control device) located far from the drive units that drive each lens of the zoom lens may include a transmission unit that sends control signals (commands) to control the zoom lens. Such a control unit allows the zoom lens to be remotely controlled.

[0059] Alternatively, the control unit may be provided with an operation unit such as a controller or buttons for remotely operating the zoom lens, thereby controlling the zoom lens in response to user input to the operation unit. For example, the operation unit may be provided with a zoom-in button and a zoom-out button. In this case, the control unit may be configured to send a signal to a zoom lens driver so that the zoom magnification increases when the user presses the zoom-in button, and decreases when the user presses the zoom-out button.

[0060] The imaging system may also have a display unit such as a liquid crystal panel that displays information (movement state) related to the zoom of the zoom lens. Information related to the zoom of the zoom lens includes, for example, the zoom magnification (zoom state) and the amount of movement (movement state) of each lens group. In this case, the user can remotely operate the zoom lens via the operation unit while viewing the information related to the zoom of the zoom lens displayed on the display unit. In this case, the display unit and the operation unit may be integrated by using, for example, a touch panel.

[0061] Although the 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 the gist of the present invention. [Explanation of symbols]

[0062] L1 First lens group L2 Second lens group La Front lens group Lb Rear lens group Ln Ln group (first subgroup) Ln2 Ln2 group (second subgroup)

Claims

1. A zoom lens having, arranged in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group including a plurality of lens groups, wherein a distance between the first lens group and the second lens group and a distance between the second lens group and the subsequent group change during zooming, the subsequent lens group comprises, arranged in order from the object side to the image side, a front lens group having positive refractive power at the telephoto end, a first sub-group having negative refractive power, a second sub-group having negative refractive power, and a rear lens group; In the subsequent lens group, a distance between the front lens group and the first subgroup, a distance between the first subgroup and the second subgroup, and a distance between the second subgroup and the rear lens group change during zooming, During focusing, the first subgroup and the second subgroup move along different trajectories; Let fn be the focal length of the first sub-group, fn2 be the focal length of the second sub-group, ft be the focal length of the zoom lens at the telephoto end, Dn be the distance on the optical axis from the lens surface of the first sub-group closest to the image side to the lens surface of the second sub-group closest to the object side when focusing on infinity at the telephoto end, and Dn2 be the distance on the optical axis from the lens surface of the second sub-group closest to the image side to the lens surface of the rear lens group closest to the object side. -0.50<fn / ft<-0.10 0.30<fn / fn2<0.60 0.20<Dn / Dn2<0.80 A zoom lens characterized by satisfying the following conditional expressions:

2. When the focal length of the front lens group at the telephoto end is fa, -1.50<fn / fa<-0.80 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the focal length of the rear lens group at the telephoto end is fb, -1.00<fn / fb<-0.40 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. When movement toward the image side is defined as positive, the amount of movement of the first sub-unit group during focusing from infinity to the closest distance at the telephoto end is defined as Mn, and the amount of movement of the second sub-unit group is defined as Mn2, 1.00<Mn / Mn2<2.00 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. the second sub-group is made up of one negative lens, When the radius of curvature of the lens surface on the object side of the negative lens is R1 and the radius of curvature of the lens surface on the image side is R2, 1.0<(R1+R2) / (R1-R2)<8.0 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the focal length of the first lens group is f1, 0.60<f1 / ft<1.20 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, -5.50<f1 / f2<-3.00 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. 8. The zoom lens according to claim 1, wherein the rear lens group has a positive refractive power.

9. 9. The zoom lens according to claim 1, wherein the first lens group is made up of three positive lenses and one negative lens.

10. A zoom lens having a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including a plurality of lens groups, arranged in this order from the object side to the image side, wherein the distance between the first lens group and the second lens group and the distance between the second lens group and the subsequent group change during zooming, the first lens group is composed of three positive lenses and one negative lens, the subsequent lens group comprises, arranged in order from the object side to the image side, a front lens group having positive refractive power at the telephoto end, a first sub-group having negative refractive power, a second sub-group having negative refractive power, and a rear lens group; In the subsequent lens group, a distance between the front lens group and the first subgroup, a distance between the first subgroup and the second subgroup, and a distance between the second subgroup and the rear lens group change during zooming, During focusing, the first subgroup and the second subgroup move along different trajectories; When the focal length of the first sub-group is fn, the focal length of the second sub-group is fn2, and the focal length of the zoom lens at the telephoto end is ft, -0.50<fn / ft<-0.10 0.30<fn / fn2<0.60 A zoom lens characterized by satisfying the following conditional expressions:

11. 10. The zoom lens according to claim 1, wherein the first lens group is composed of two positive lenses and one negative lens.

12. 12. The zoom lens according to claim 1, wherein the second lens group includes, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens.

13. 13. The zoom lens according to claim 1, wherein the first sub-group is configured by a cemented lens made up of a positive lens and a negative lens, arranged in that order from the object side to the image side.

14. 14. The zoom lens according to claim 1, wherein the second sub-lens group is formed of a negative meniscus lens having a convex shape facing the object side.

15. 15. The zoom lens according to claim 1, wherein the subsequent lens group consists of, arranged in order from the object side to the image side, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, a sixth lens group having negative refractive power, and a seventh lens group having positive refractive power.

16. 15. The zoom lens according to claim 1, wherein the subsequent lens group consists of, arranged in order from the object side to the image side, a third lens group having positive refractive power, a fourth lens group having negative refractive power, a fifth lens group having negative refractive power, a sixth lens group having positive refractive power, and a seventh lens group having negative refractive power.

17. A zoom lens having a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including a plurality of lens groups, arranged in this order from the object side to the image side, wherein the distance between the first lens group and the second lens group and the distance between the second lens group and the subsequent group change during zooming, the subsequent lens group comprises, arranged in order from the object side to the image side, a front lens group having positive refractive power at the telephoto end, a first sub-group having negative refractive power, a second sub-group having negative refractive power, and a rear lens group; the front lens group is made up of a third lens group having a positive refractive power, the first subgroup is made up of a fourth lens group having a negative refractive power, the second subgroup is made up of a fifth lens group having a negative refractive power, and the rear lens group is made up of a sixth lens group having a positive refractive power and a seventh lens group having a negative refractive power, In the subsequent lens group, a distance between the front lens group and the first subgroup, a distance between the first subgroup and the second subgroup, and a distance between the second subgroup and the rear lens group change during zooming, During focusing, the first subgroup and the second subgroup move along different trajectories; When the focal length of the first sub-group is fn, the focal length of the second sub-group is fn2, and the focal length of the zoom lens at the telephoto end is ft, -0.50<fn / ft<-0.10 0.30<fn / fn2<0.60 A zoom lens characterized by satisfying the following conditional expressions:

18. 15. The zoom lens according to claim 1, wherein the subsequent lens group consists of, arranged in order from the object side to the image side, a third lens group having positive refractive power, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, a seventh lens group having negative refractive power, and an eighth lens group having positive refractive power.

19. A zoom lens having a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including a plurality of lens groups, arranged in this order from the object side to the image side, wherein the distance between the first lens group and the second lens group and the distance between the second lens group and the subsequent group change during zooming, the subsequent lens group comprises, arranged in order from the object side to the image side, a front lens group having positive refractive power at the telephoto end, a first sub-group having negative refractive power, a second sub-group having negative refractive power, and a rear lens group; the front lens group is composed of a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, the first subgroup is composed of a sixth lens group having a negative refractive power, the second subgroup is composed of a seventh lens group having a negative refractive power, and the rear lens group is composed of an eighth lens group having a positive refractive power, In the subsequent lens group, a distance between the front lens group and the first subgroup, a distance between the first subgroup and the second subgroup, and a distance between the second subgroup and the rear lens group change during zooming, During focusing, the first subgroup and the second subgroup move along different trajectories; When the focal length of the first sub-group is fn, the focal length of the second sub-group is fn2, and the focal length of the zoom lens at the telephoto end is ft, -0.50<fn / ft<-0.10 0.30<fn / fn2<0.60 A zoom lens characterized by satisfying the following conditional expressions:

20. 15. The zoom lens according to claim 1, wherein the subsequent lens group comprises, arranged in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a positive refractive power.

21. A zoom lens according to any one of claims 1 to 20; and an image sensor that receives an image formed by the zoom lens.

22. 21. An imaging system comprising: the zoom lens according to claim 1; and a control unit that controls the zoom lens during zooming.

23. 23. The imaging system according to claim 22, wherein the control unit is configured as a separate unit from the zoom lens and includes a transmission unit that transmits a control signal for controlling the zoom lens.

24. 24. The imaging system according to claim 22, wherein the control unit is configured as a separate unit from the zoom lens and has an operation unit for operating the zoom lens.

25. 25. The imaging system according to claim 22, further comprising a display unit that displays information related to the zoom of the zoom lens.

Images