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

Abstract

To provide a zoom lens that has a high optical performance over an entire zoom range and is compact and light-weighted, and an imaging apparatus and an imaging system having the same.SOLUTION: A zoom lens has a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, which are arranged in this order from an object side to an image side. In the zoom lens, in zooming from a wide angle end to a telephoto end, the first lens group moves, an interval between the first lens group and the second lens group is increased, an interval between the second lens group and the third lens group is reduced, and an interval between the third lens group and the fourth lens group is reduced. The fourth lens group is composed of a first lens with positive refractive power and a second lens with positive or negative refractive power arranged in this order from the object side to the image side. A distance on an optical axis from a lens surface on the most object side of the first lens group at the telephoto end to an image surface, a focal distance of the zoom lens at the telephoto end, and a refractive index of the second lens are each appropriately set.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, as well as be small and lightweight. To meet these requirements, a zoom lens has been proposed that has first to fourth lens groups with positive, negative, positive, and positive refractive powers arranged in this order from the object side to the image side, and in which the spacing between adjacent lens groups changes during zooming (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-333039 Summary of the Invention [Problem to be solved by the invention]

[0004] In general, to reduce the size of a zoom lens, it is effective to adopt a telephoto-type power arrangement at the telephoto end, strengthening the positive refractive power on the object side and the negative refractive power on the image side. However, strengthening the refractive power of each lens group increases the fluctuations in various aberrations that occur during zooming, making it difficult to effectively correct various aberrations with a small number of lens elements. Therefore, to achieve both a compact and lightweight zoom lens, it is important to appropriately set the refractive power and lens configuration of each lens group.

[0005] An object of the present invention is to provide a small, lightweight zoom lens that has high optical performance over the entire zoom range, and an imaging device and imaging system that include the same. [Means for solving the problem]

[0006] A zoom lens according to one aspect of the present invention comprises, 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, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, and during zooming from the wide-angle end to the telephoto end, the first lens group moves, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group decreases, and the distance between the fourth lens group and the fifth lens group decreases. A variable-lens zoom lens, wherein during focusing, one lens group arranged closer to the image side than the fourth lens group moves, while the first to fourth lens groups remain stationary, and the fourth lens group consists of a first lens with positive refractive power and a second lens with positive or negative refractive power arranged in that order from the object side to the image side, and wherein the distance on the optical axis from the lens surface of the first lens group closest to the object side to the image plane at the telephoto end is TLt, the focal length of the zoom lens at the telephoto end is ft, and the refractive index of the second lens is ndGa, 0.30 <TLt / ft<0.80 1.40 <ndGa<1.72 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 small, lightweight zoom lens that has high optical performance over the entire zoom range, as well as an imaging device and an imaging system that include the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a zoom lens of a first embodiment at a wide-angle end. [Figure 2] 3A and 3B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 1. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end according to a second embodiment. [Figure 4] 10A and 10B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 2. [Figure 5]FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end according to a third embodiment. [Figure 6] 10A and 10B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 3. [Figure 7] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end of Example 4. [Figure 8] 10A and 10B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 4. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end according to a fifth embodiment. [Figure 10] 10A and 10B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 5. [Figure 11] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end of a sixth embodiment. [Figure 12] 13A and 13B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 6. [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, 3, 5, 7, 9, and 11 are cross-sectional views of the zoom lenses of Examples 1 to 6 at the wide-angle end when focused on infinity (infinity focused state), respectively. 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 devices 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 group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, and a fourth lens group L4 with positive refractive power.

[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] Additionally, SP denotes an aperture stop. IP denotes an image plane, on which the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed when the zoom lens of each embodiment is used as the imaging optical system of a digital still camera or digital video camera. When the zoom lens of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is placed on 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. The wide-angle end and the telephoto end are zoom states when the lens group that moves during zooming is located at both ends of the range of movement in the optical axis direction due to the mechanism. In addition, in the zoom lens of each embodiment, each lens group moves in the direction of the dotted arrow when focusing from infinity to a close distance.

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

[0017] 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 (°).

[0018] Next, the characteristic configuration of the zoom lens of each embodiment will be described.

[0019] During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves, widening the gap between the first lens unit L1 and the second lens unit L2, narrowing the gap between the second lens unit L2 and the third lens unit L3, and narrowing the gap between the third lens unit L3 and the fourth lens unit L4. This results in a telephoto-type power arrangement at the telephoto end, which is advantageous for shortening the overall length of the zoom lens. Furthermore, the second lens unit L2 remains stationary during zooming. This reduces the amount of relative decentering error between the first lens unit L1 and the second lens unit L2, thereby suppressing degradation of optical performance.

[0020] In such a configuration, the fourth lens group L4 moves a large distance during zooming from the wide-angle end to the telephoto end, so it is important to appropriately design the lens configuration of the fourth lens group L4 to suppress fluctuations in various aberrations. The fourth lens group L4 is composed of, arranged in order from the object side to the image side, a positive lens (first lens) Gp and a lens (second lens) Ga with positive or negative refractive power. That is, in the zoom lens of each embodiment, fluctuations in various aberrations, such as spherical aberration and curvature of field, during zooming can be suppressed with a small number of lenses. It is preferable that at least one of the lens surfaces of the positive lens Gp and the lens Ga be aspherical.

[0021] The zoom lens of each embodiment satisfies the following conditional expressions (1) and (2).

[0022] 0.30 <TLt / ft<0.80 (1) 1.40 <ndGa<1.72 (2) Here, TLt is the total length of the zoom lens at the telephoto end (the distance on the optical axis from the lens surface of the first lens group L1 closest to the object to the image plane), ft is the focal length of the zoom lens at the telephoto end, and ndGa is the refractive index of the lens Ga with positive or negative refractive power included in the fourth lens group L4.

[0023] Conditional expression (1) defines the overall length of the zoom lens at the telephoto end and the focal length of the zoom lens at the telephoto end. By appropriately setting these conditions, it becomes easier to reduce the size of the zoom lens. If the lower limit of conditional expression (1) is exceeded, and the overall length of the zoom lens at the telephoto end becomes too short relative to the focal length of the zoom lens at the telephoto end, the refractive power of each lens group becomes strong, making it difficult to suppress fluctuations in various aberrations that occur during zooming, which is undesirable. If the upper limit of conditional expression (1) is exceeded, and the overall length of the zoom lens at the telephoto end becomes too long relative to the focal length of the zoom lens at the telephoto end, it becomes difficult to reduce the size of the zoom lens, which is undesirable.

[0024] Conditional formula (2) defines the refractive index of the lens Ga. Generally, the higher the refractive index of a lens, the greater the specific gravity. If the refractive index of the lens Ga is reduced below the lower limit of conditional formula (2), the curvature of the lens surface will be increased in order to obtain the necessary refractive power, making it difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming, which is undesirable. If the refractive index of the lens Ga is increased above the upper limit of conditional formula (2), the specific gravity of the lens Ga will be increased, making it difficult to reduce the weight of the zoom lens, which is undesirable.

[0025] With the above-described configuration, it is possible to realize a small, lightweight zoom lens that has high optical performance over the entire zoom range.

[0026] 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).

[0027] 0.40 <TLt / ft<0.79 (1a) 1.43 <ndGa<1.71 (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).

[0028] 0.50 <TLt / ft<0.78 (1b) 1.45 <ndGa<1.70 (2b) Next, the configurations that are preferably satisfied in the zoom lens of each embodiment will be described.

[0029] It is preferable that the first lens unit L1, which has positive refractive power and is closest to the object, moves toward the object during zooming from the wide-angle end to the telephoto end, thereby shortening the overall length of the zoom lens at the wide-angle end and enabling the zoom lens to be made more compact.

[0030] The second lens group L2 is preferably composed of two or less lenses, which makes it easier to reduce the weight of the second lens group L2.More preferably, the second lens group L2 is composed of a lens with negative refractive power and a lens with positive refractive power, arranged in that order from the object side to the image side.

[0031] The third lens group L3 is preferably composed of two or less lenses, which makes it easier to reduce the weight of the third lens group L3.More preferably, the third lens group L3 is composed of a lens with positive refractive power and a lens with negative refractive power, arranged in that order from the object side to the image side.

[0032] The lens group located closer to the image side than the aperture diaphragm SP tends to have a small effective diameter of the light beam. Therefore, if the lens group located closer to the image side than the aperture diaphragm SP is used as the focusing lens group, the holding mechanism and drive mechanism can be simplified and the zoom lens can be made more compact. Furthermore, if the focusing lens group is composed of two or fewer lenses, the focusing lens group can be made lighter. In addition, since the magnification change effect is relatively small on the image side than the aperture diaphragm SP, the change in image magnification can be made small when focusing from infinity to a close distance. Therefore, the change in the angle of view when the subject changes from infinity to a close distance can be made small, allowing for appropriate video shooting.

[0033] By moving all or part of any of the lens groups in a direction perpendicular to the optical axis, it is possible to achieve the effect of reducing camera shake. In particular, it is preferable to use the second lens group L2, which is fixed during zooming, as the camera shake correction lens group. This configuration reduces the amount of movement of the camera shake correction lens group and facilitates compactness.

[0034] 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 (12).

[0035] 0.001<|fGp / fGa|<0.500 (3) 1.00 <SGa<4.00 (4) 0.3 <ML4 / ML1<3.0 (5) -0.80 <fL2 / fL1<-0.20 (6) 0.05 <fL4 / ft<0.50 (7) 0.10 <fL4 / fL1<0.70 (8) 0.05 <fL4 / fL3<1.00 (9) 55<νdGp<99 (10) 55<νdL1Pave.<99 (11) 55<νdL3Pave.<99 (12) Here, fGp is ​​the focal length of the positive lens Gp included in the fourth lens group L4. fGa is the focal length of the lens Ga with positive or negative refractive power included in the fourth lens group L4. SGa is the specific gravity of the lens Ga. ML1 is the movement amount of the first lens group L1 during zooming from the wide-angle end to the telephoto end. ML4 is the movement amount of the fourth lens group L4 during zooming from the wide-angle end to the telephoto end. fL1 is the focal length of the first lens group L1. fL2 is the focal length of the second lens group L2. fL3 is the focal length of the third lens group L3. fL4 is the focal length of the fourth lens group L4. νdGp is ​​the Abbe number for the d-line of the positive lens Gp. νdL1Pave. is the average Abbe number for the d-line of the positive lenses included in the first lens group L1. νdL3Pave. is the average value of the Abbe numbers for the d-line of the positive lenses included in the third lens unit L3.

[0036] Conditional expression (3) defines the focal length of the positive lens Gp and the focal length of the lens Ga. If the focal length of the lens Ga becomes longer below the lower limit of conditional expression (3), the refractive power of the lens Ga becomes weaker, making it difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming, which is undesirable. If the focal length of the lens Ga becomes shorter above the upper limit of conditional expression (3), the refractive power of the fourth lens group L4 becomes weaker, making it undesirable for the fourth lens group L4 to move a longer distance during zooming.

[0037] Conditional formula (4) defines the specific gravity of the lens Ga. Generally, the higher the specific gravity of a lens, the higher the refractive index. If the specific gravity of the lens Ga decreases below the lower limit of conditional formula (4), the curvature of the lens surface increases in order to obtain the necessary refractive power, which is undesirable because it becomes difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming. If the specific gravity of the lens Ga increases above the upper limit of conditional formula (4), it becomes difficult to reduce the weight of the zoom lens, which is undesirable.

[0038] Conditional expression (5) defines the amount of movement of the first lens group L1 during zooming from the wide-angle end to the telephoto end and the amount of movement of the fourth lens group L4 during zooming from the wide-angle end to the telephoto end. If the lower limit of conditional expression (5) is exceeded, the amount of movement of the fourth lens group L4 becomes small, which is undesirable because it becomes difficult to achieve a high zoom ratio. If the upper limit of conditional expression (5) is exceeded, the amount of movement of the fourth lens group L4 becomes large, which is undesirable because it becomes difficult to make the zoom lens compact.

[0039] Conditional expression (6) defines the focal length of the first lens group L1 and the focal length of the second lens group L2. If the focal length of the first lens group L1 becomes long by falling below the lower limit of conditional expression (6), the amount of movement of the first lens group L1 during zooming from the wide-angle end to the telephoto end becomes large, making it difficult to reduce the size of the zoom lens, which is undesirable. If the focal length of the first lens group L1 becomes short by exceeding the upper limit of conditional expression (6), it becomes difficult to correct spherical aberration generated in the first lens group L1, which is undesirable.

[0040] Conditional expression (7) defines the focal length of the zoom lens at the telephoto end and the focal length of the fourth lens unit L4. If the focal length of the fourth lens unit L4 becomes shorter by falling below the lower limit of conditional expression (7), it becomes difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming, which is undesirable. If the focal length of the zoom lens at the telephoto end becomes shorter by exceeding the upper limit of conditional expression (7), it becomes difficult to achieve a high zoom ratio, which is undesirable.

[0041] Conditional expression (8) defines the focal length of the first lens group L1 and the focal length of the fourth lens group L4. If the focal length of the fourth lens group L4 falls below the lower limit of conditional expression (8) and becomes short, it becomes difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming, which is undesirable. If the focal length of the fourth lens group L4 exceeds the upper limit of conditional expression (8) and becomes long, it becomes undesirable because the refractive power of the fourth lens group L4 weakens and the amount of movement of the fourth lens group L4 that occurs during zooming becomes long.

[0042] Conditional expression (9) defines the focal lengths of the third lens group L3 and the fourth lens group L4. If the focal length of the fourth lens group L4 is shortened below the lower limit of conditional expression (9), it becomes difficult to suppress fluctuations in various aberrations, such as spherical aberration and curvature of field, that occur during zooming, which is undesirable. If the focal length of the fourth lens group L4 is lengthened above the upper limit of conditional expression (9), the refractive power of the fourth lens group L4 weakens, and the amount of movement of the fourth lens group L4 that occurs during zooming becomes long, which is undesirable.

[0043] Conditional expression (10) defines the Abbe number of the positive lens Gp for the d-line. If the Abbe number of the positive lens Gp for the d-line falls below the lower limit of conditional expression (10) and becomes small, it becomes difficult to correct axial chromatic aberration at the telephoto end, which is undesirable. If the Abbe number of the positive lens Gp for the d-line falls above the upper limit of conditional expression (10) and becomes large, it becomes difficult to correct axial chromatic aberration at the wide-angle end, which is undesirable.

[0044] Conditional expression (11) defines the average value of the Abbe numbers for the d-line of the positive lenses included in the first lens group L1. If the average value of the Abbe numbers for the d-line of the positive lenses included in the first lens group L1 becomes small below the lower limit of conditional expression (11), it becomes difficult to correct axial chromatic aberration and chromatic aberration of magnification at the telephoto end, which is undesirable. If the average value of the Abbe numbers for the d-line of the positive lenses included in the first lens group L1 becomes large above the upper limit of conditional expression (11), it becomes difficult to correct chromatic aberration of magnification at the wide-angle end, which is undesirable.

[0045] Conditional expression (12) defines the average value of the Abbe numbers for the d-line of the positive lenses included in the third lens group L3. If the average value of the Abbe numbers for the d-line of the positive lenses included in the third lens group L3 falls below the lower limit of conditional expression (12) and becomes small, it becomes difficult to correct longitudinal chromatic aberration at the telephoto end, which is undesirable. If the average value of the Abbe numbers for the d-line of the positive lenses included in the third lens group L3 exceeds the upper limit of conditional expression (12) and becomes large, it becomes difficult to correct longitudinal chromatic aberration at the wide-angle end, which is undesirable.

[0046] It is preferable that the numerical ranges of the conditional expressions (3) to (12) be set to the numerical ranges of the following conditional expressions (3a) to (12a).

[0047] 0.002<|fGp / fGa|<0.450 (3a) 1.00 <SGa<3.90 (4a) 0.4 <ML4 / ML1<2.5 (5a) -0.70 <fL2 / fL1<-0.23 (6a) 0.08 <fL4 / ft<0.40 (7a) 0.15 <fL4 / fL1<0.60 (8a) 0.10 <fL4 / fL3<0.90 (9a) 58<νdGp<90 (10a) 58<νdL1Pave.<90 (11a) 58<νdL3Pave.<90 (12a) It is more preferable that the numerical ranges of the conditional expressions (3) to (12) be the numerical ranges of the following conditional expressions (3b) to (12b).

[0048] 0.004<|fGp / fGa|<0.430 (3b) 1.00 <SGa<3.80 (4b) 0.5 <ML4 / ML1<2.3 (5b) -0.60 <fL2 / fL1<-0.25 (6b) 0.10 <fL4 / ft<0.30 (7b) 0.20 <fL4 / fL1<0.50 (8b) 0.15 <fL4 / fL3<0.80 (9b) 60<νdGp<85 (10b) 60<νdL1Pave.<85 (11b) 60<νdL3Pave.<85 (12b) Next, the zoom lens of each embodiment will be described in detail.

[0049] The zoom lenses of Examples 1 and 2 are made up of a first lens unit L1 to a fifth lens unit L5, which are arranged in order from the object side to the image side and have positive, negative, positive, positive, negative refractive powers.

[0050] The zoom lens of the third embodiment is made up of a first lens unit L1 to a sixth lens unit L6, which are arranged in order from the object side to the image side and have positive, negative, positive, positive, positive, negative refractive powers.

[0051] The zoom lens of Example 4 is made up of a first lens unit L1 to a sixth lens unit L6, which are arranged in order from the object side to the image side and have positive, negative, positive, positive, negative, and positive refractive powers.

[0052] The zoom lens of the fifth embodiment is made up of a first lens unit L1 to a sixth lens unit L6, which are arranged in order from the object side to the image side and have positive, negative, positive, positive, negative, negative refractive powers.

[0053] The zoom lens of Example 6 is made up of a first lens unit L1 to a seventh lens unit L7, arranged in order from the object side to the image side, having positive, negative, positive, positive, negative, positive, negative refractive powers.

[0054] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below.

[0055] 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:

[0056] 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. "Lens group" is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens.

[0057] If the optical surface is aspherical, an asterisk (*) is added to the right of the surface number. The aspherical shape is expressed as follows: X is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of each order. X=(h 2 / R) / [1+{1-(1+K)(h / R) 2} 1 / 2 +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means. [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 103.753 4.61 1.48749 70.2 2∞0.15 3 156.943 1.90 1.61340 44.3 4 53.406 5.96 1.49700 81.5 5 380.919 (variable) 6 -101.313 1.00 1.77250 49.6 7 28.984 2.85 2.05090 26.9 8 55.746 (variable) 9 (Aperture) ∞ 0.60 10 29.396 5.49 1.48749 70.2 11 -59.441 5.76 12 -31.194 1.30 2.00100 29.1 13 -75.081 (variable) 14 415.256 3.50 1.48749 70.2 15 -30.719 6.37 16* 49.641 3.00 1.53110 55.9 17* 47.793 (variable) 18 -992.387 2.22 1.84666 23.9 19 -42.688 0.95 1.80400 46.5 20 39.970 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-4.71184e-005 A 6=-1.69647e-007 A 8= 6.47160e-010 A10=-6.68961e-012 A12= 3.22858e-014 Page 17 K = 0.00000e+000 A 4=-4.13756e-005 A 6=-1.60763e-007 A 8= 6.71955e-010 A10=-4.98484e-012 A12= 2.62649e-014 Various data Zoom ratio 3.87 Wide-angle Mid-range Telephoto Focal length 100.31 200.00 388.00 F-number 5.77 7.17 8.24 Half angle of view (degrees) 12.17 6.17 3.19 Image height 21.64 21.64 21.64 Lens total length 182.61 225.42 258.53 BF 48.26 75.67 110.31 d 5 16.89 59.69 92.80 d 8 41.71 26.23 3.60 d13 11.14 6.27 4.09 d17 18.95 11.89 2.07 d20 48.26 75.67 110.31 Zoom lens group data Group starting plane focal length 1 1 192.87 2 6 -59.32 3 9 107.44 4 14 58.11 5 18 -50.03 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 126.501 4.61 1.48749 70.2 2∞0.15 3 207.173 1.90 1.61340 44.3 4 61.597 5.96 1.49700 81.5 5 4918.524 (variable) 6 -94.203 1.00 1.77250 49.6 7 29.921 2.85 2.05090 26.9 8 60.023 (variable) 9 (Aperture) ∞ 0.60 10 33.734 5.49 1.48749 70.2 11 -58.883 5.76 12 -33.258 1.30 2.00100 29.1 13 -79.851 (variable) 14 1506.449 3.50 1.59282 68.6 15 -37.554 8.00 16* 31.917 3.00 1.69680 55.5 17* 28.523 (variable) 18 194.129 2.22 1.92286 20.9 19 -170.453 0.95 1.80400 46.5 20 42.279 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-2.99799e-005 A 6=-8.79741e-008 A 8= 2.94045e-011 A10=-2.46494e-013 A12= 2.58866e-015 Page 17 K = 0.00000e+000 A 4=-2.99930e-005 A 6=-1.00834e-007 A 8= 1.23547e-010 A10=-6.70110e-013 A12= 5.83244e-015 Various data Zoom ratio 3.50 Wide-angle Mid-range Telephoto Focal length 100.00 187.86 350.00 F-number 5.77 7.05 8.24 Half angle of view (degrees) 12.21 6.57 3.54 Image height 21.64 21.64 21.64 Lens length 191.67 234.47 267.58 BF 53.64 82.65 117.62 d 5 16.89 59.69 92.80 d 8 41.71 26.23 3.60 d13 11.14 6.27 4.09 d17 21.00 12.34 2.17 d20 53.64 82.65 117.62 Zoom lens group data Group starting plane focal length 1 1 207.06 2 6 -60.92 3 9 126.02 4 14 64.83 5 18 -74.57 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 72.901 5.00 1.48749 70.2 2 -5116.308 0.15 3 96.485 1.90 1.80610 40.7 4 38.718 5.96 1.59410 60.5 5 151.108 (variable) 6 -138.145 1.00 1.75500 52.3 7 25.532 2.85 2.05090 26.9 8 44.316 (variable) 9 (Aperture) ∞ 0.60 10 40.918 3.54 1.59410 60.5 11 -110.268 5.49 12 -40.305 1.30 2.00069 25.5 13 -86.998 (variable) 14 -32.977 2.71 1.59410 60.5 15 -19.917 0.36 16* -28.313 2.50 1.68040 18.1 17* -28.575 (variable) 18 43.490 1.00 1.84666 23.8 19 34.968 2.47 1.49700 81.5 20 73.461 (variable) 21 1108.890 3.10 1.92119 24.0 22 -60.469 0.95 1.83481 42.7 23 47.468 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-6.21812e-005 A 6=-6.99576e-008 A 8=-9.13103e-011 A10=-2.47166e-012 A12= 1.49716e-014 Page 17 K = 0.00000e+000 A 4=-4.63866e-005 A 6=-2.29469e-008 A 8=-7.19123e-011 A10=-7.36741e-013 A12= 5.69474e-015 Various data Zoom ratio 4.29 Wide-angle Mid-range Telephoto Focal length 70.00 149.64 300.00 F-number 4.20 6.04 7.20 Half angle of view (degrees) 17.17 8.23 ​​4.12 Image height 21.64 21.64 21.64 Lens total length 170.19 199.65 232.45 BF 23.56 62.47 105.22 d 5 4.56 34.02 66.82 d 8 41.56 24.34 5.16 d13 19.67 11.78 3.01 d17 1.00 4.23 7.82 d20 38.95 21.92 3.52 d23 23.56 62.47 105.22 Zoom lens group data Group starting plane focal length 1 1 165.49 2 6 -57.39 3 9 120.57 4 14 77.38 5 18 334.80 6 21 -65.42 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 137.194 3.32 1.48749 70.2 2 556.213 0.15 3 169.321 1.90 1.61340 44.3 4 59.780 7.39 1.49700 81.5 5 -492.395 (variable) 6 -250.411 1.00 1.75500 52.3 7 25.858 2.85 2.05090 26.9 8 43.298 (variable) 9 (Aperture) ∞ 0.60 10 31.879 4.94 1.49700 81.5 11 131.830 9.29 12 -30.439 1.30 2.00069 25.5 13 -43.792 (variable) 14 35.880 4.30 1.49700 81.5 15 -37.877 8.00 16* -26.275 2.50 1.68040 18.1 17* -29.773 (variable) 18 -176.955 2.56 2.00069 25.5 19 -29.993 0.95 1.83481 42.7 20 32.008 (variable) 21 44.117 4.00 1.48749 70.2 22 78.183 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-5.75946e-005 A 6= 5.33432e-008 A 8= 7.02179e-010 A10=-4.69444e-012 A12= 1.53060e-014 Page 17 K = 0.00000e+000 A 4=-4.17692e-005 A 6= 6.39652e-008 A 8= 6.52144e-010 A10=-5.41304e-012 A12= 1.71572e-014 Various data Zoom ratio 3.50 Wide-angle Mid-range Telephoto Focal length 100.01 181.05 350.01 F-number 5.80 7.02 8.00 Half angle of view (degrees) 12.21 6.81 3.54 Image height 21.64 21.64 21.64 Lens total length 199.48 233.16 270.66 BF 48.68 44.50 39.84 d 5 20.44 54.13 91.63 d 8 36.85 20.92 3.19 d13 17.18 11.36 4.88 d17 11.26 8.69 1.00 d20 10.00 38.50 75.05 d22 48.68 44.50 39.84 Zoom lens group data Group starting plane focal length 1 1 187.56 2 6 -64.18 3 9 259.39 4 14 41.78 5 18 -37.94 6 21 200.00 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 94.097 6.08 1.59349 67.0 2 279.844 0.15 3 132.657 1.90 1.80400 46.5 4 64.446 9.51 1.43875 94.7 5 -9355.982 (variable) 6 -511.756 1.00 1.80400 46.5 7 36.945 2.85 1.80000 29.8 8 118.549 (variable) 9 (Aperture) ∞ 0.60 10 32.947 3.11 1.49700 81.5 11 157.122 2.93 12 -116.586 1.30 2.05090 26.9 13 2998.496 (variable) 14 175.192 2.66 1.49700 81.5 15 -59.566 0.15 16* -66.478 2.50 1.58313 59.4 17* -44.684 (variable) 18 460.969 2.24 1.63980 34.5 19 -38.414 0.95 1.61997 63.9 20 38.098 (variable) 21 -69.822 1.50 1.49700 81.5 22 -437.675 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-1.63197e-005 A 6= 7.60315e-009 A 8= 1.56026e-010 A10=-1.35273e-012 A12= 4.84046e-015 Page 17 K = 0.00000e+000 A 4=-1.03566e-005 A 6= 9.98871e-009 A 8= 1.56578e-010 A10=-1.46972e-012 A12= 5.23392e-015 Various data Zoom ratio 2.40 Wide-angle Mid-range Telephoto Focal length 250.00 415.97 600.00 F-number 7.49 9.70 11.33 Half angle of view (degrees) 4.95 2.98 2.07 Image height 21.64 21.64 21.64 Lens total length 301.60 319.38 339.18 BF 70.61 115.58 165.65 d 5 65.65 83.44 103.23 d 8 81.92 44.37 2.56 d13 14.00 11.84 9.43 d17 20.00 10.15 1.00 d20 10.00 14.59 17.89 d22 70.61 115.58 165.65 Zoom lens group data Group starting plane focal length 1 1 211.63 2 6 -118.32 3 9 304.85 4 14 65.20 5 18 -69.83 6 21 -167.38 [Numerical Example 6] Unit: mm Surface Data Surface number rd nd νd 1 145.510 3.89 1.48749 70.2 2 -1020.025 0.15 3 149.327 1.90 1.61340 44.3 4 56.290 5.86 1.49700 81.5 5 880.084 (variable) 6 -333.123 1.00 1.75500 52.3 7 25.217 2.85 2.00100 29.1 8 45.684 (variable) 9 (Aperture) ∞ 0.60 10 31.054 3.08 1.49700 81.5 11 242.551 4.66 12 -33.419 1.30 2.00069 25.5 13 -50.662 (variable) 14 90.524 3.54 1.49700 81.5 15 -35.033 7.01 16* -67.638 2.50 1.53110 55.9 17* -132.220 (variable) 18 -1708.601 2.01 2.00069 25.5 19 -52.544 0.95 1.83481 42.7 20 41.556 (variable) 21 45.134 6.21 1.48749 70.2 22 -127.650 (variable) 23 -91.087 1.50 1.49700 81.5 24 70.863 (variable) Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4=-2.55278e-005 A 6=-4.49567e-008 A 8= 1.37496e-009 A10=-1.47479e-011 A12= 5.36458e-014 Page 17 K = 0.00000e+000 A 4=-1.50978e-005 A 6=-4.65186e-008 A 8= 1.71815e-009 A10=-1.92636e-011 A12= 7.55778e-014 Various data Zoom ratio 3.50 Wide-angle Mid-range Telephoto Focal length 100.00 188.15 350.00 F-number 5.80 7.27 8.00 Half angle of view (degrees) 12.21 6.56 3.54 Image height 21.64 21.64 21.64 Lens total length 204.59 235.89 270.72 BF 29.91 40.16 51.57 d 5 22.98 54.27 89.11 d 8 47.93 27.61 4.98 d13 15.63 8.71 1.00 d17 19.98 13.77 1.00 d20 9.32 36.48 72.56 d22 9.83 5.88 1.48 d24 29.91 40.16 51.57 Zoom lens group data Group starting plane focal length 1 1 187.87 2 6 -70.40 3 9 199.99 4 14 61.93 5 18 -57.14 6 21 69.21 7 23 -79.95 The various values ​​in each numerical example are summarized in Table 1 below.

[0058] [Table 1]

[0059] [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 6. 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.

[0060] 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.

[0061] 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.

[0062] 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 may be, for example, the zoom magnification (zoom state) or the movement amount (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 operation unit may be integrated by using, for example, a touch panel.

[0063] 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]

[0064] L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group Gp positive lens (first lens) Ga lens (second lens)

Claims

1. A zoom lens comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group, which are arranged in this order from the object side to the image side, wherein, during zooming from a wide-angle end to a telephoto end, the first lens group moves, a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group decreases, a distance between the third lens group and the fourth lens group decreases, and a distance between the fourth lens group and the fifth lens group changes, During focusing, one lens group disposed closer to the image side than the fourth lens group moves, and the first to fourth lens groups remain stationary; the fourth lens group includes, in order from the object side to the image side, a first lens having a positive refractive power and a second lens having a positive or negative refractive power; When the distance on the optical axis from the lens surface of the first lens group closest to the object side at the telephoto end to the image plane is TLt, the focal length of the zoom lens at the telephoto end is ft, and the refractive index of the second lens is ndGa, 0.30<TLt / ft<0.80 1.40<ndGa<1.72 A zoom lens characterized by satisfying the following conditional expressions:

2. When the specific gravity of the second lens is SGa, 1.00<SGa<4.00 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end is ML1 and the amount of movement of the fourth lens group during zooming from the wide-angle end to the telephoto end is ML4, 0.3<ML4 / ML1<3.0 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. When the focal length of the first lens group is fL1 and the focal length of the second lens group is fL2, -0.80<fL2 / fL1<-0.20 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. When the focal length of the fourth lens group is fL4, 0.05<fL4 / ft<0.50 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 fL1 and the focal length of the fourth lens group is fL4, 0.10<fL4 / fL1<0.70 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the third lens group is fL3 and the focal length of the fourth lens group is fL4, 0.05<fL4 / fL3<1.00 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. When the Abbe number of the first lens with respect to the d-line is νdGp, 55<νdGp<99 8. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. When the average value of the Abbe number of the material of the positive lens included in the first lens group with respect to the d line is νdL1Pave., 55<νdL1Pave. <99 9. The zoom lens according to claim 1, wherein the following condition is satisfied:

10. When the average value of the Abbe numbers of the positive lenses included in the third lens group with respect to the d-line is νdL3Pave., 55<νdL3Pave. <99 10. The zoom lens according to claim 1, wherein the following condition is satisfied:

11. 11. The zoom lens according to claim 1, wherein the second lens group comprises, in order from the object side to the image side, a lens having a negative refractive power and a lens having a positive refractive power.

12. 12. The zoom lens according to claim 1, wherein the third lens group comprises, in order from the object side to the image side, a lens having a positive refractive power and a lens having a negative refractive power.

13. A zoom lens as described in any one of claims 1 to 12, characterized in that at least one of the lens surfaces of the second lens is aspherical.

14. 14. The zoom lens according to claim 1, wherein the second lens group remains stationary during zooming from the wide-angle end to the telephoto end.

15. an aperture stop; 15. The zoom lens according to claim 1, wherein a lens group disposed closer to the image side than the aperture stop moves during focusing.

16. 16. The zoom lens according to claim 1, comprising, in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group having negative refractive power.

17. 16. The zoom lens according to claim 1, comprising, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group having positive refractive power, and a sixth lens group having negative refractive power.

18. 16. The zoom lens according to claim 1, comprising, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group having negative refractive power, and a sixth lens group having positive refractive power.

19. 16. The zoom lens according to claim 1, comprising, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group having negative refractive power, and a sixth lens group having negative refractive power.

20. 16. The zoom lens according to claim 1, comprising, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group having negative refractive power, a sixth lens group having positive refractive power, and a seventh lens group having negative 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