Zoom lens, and imaging apparatus 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 are required to have high optical performance, and to be small and lightweight. In order 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, in order to make a zoom lens compact, it is effective to adopt a telephoto type power arrangement at the telephoto end and to strengthen the positive refractive power on the object side and the negative refractive power on the image side. However, if the refractive power of each lens group is strengthened, the fluctuation of various aberrations accompanying zooming becomes large, and it becomes difficult to satisfactorily correct various aberrations with a small number of lenses. Therefore, in order to achieve both compactness and light weight of a 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 having high optical performance over the entire zoom range, and an imaging device and an imaging system having the same. [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 with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with 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. is a variable-lens zoom lens, in which, during focusing, one lens group arranged closer to the image side than the fourth lens group moves, and the first to fourth lens groups are 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, wherein the distance on the optical axis from the lens surface closest to the object side of the first lens group 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 The present invention is characterized in that the following conditional expression is satisfied: Effect of the Invention

[0007] According to the present invention, it is possible to provide a small, lightweight zoom lens having high optical performance over the entire zoom range, and an imaging device and an imaging system having the same. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a zoom lens of a first embodiment at a wide-angle end. [Diagram 2] 3A and 3B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 1. [Diagram 3] FIG. 11 is a cross-sectional view of a zoom lens at a wide-angle end according to a second embodiment. [Figure 4] 13A and 13B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 2. [Diagram 5]FIG. 11 is a cross-sectional view of a zoom lens at a wide-angle end according to a third embodiment. [Figure 6] 13A and 13B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 3. [Figure 7] FIG. 11 is a cross-sectional view of a zoom lens at a wide-angle end according to a fourth embodiment. [Figure 8] 13A and 13B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 4. [Figure 9] FIG. 13 is a cross-sectional view of a zoom lens at a wide-angle end according to a fifth embodiment. [Figure 10] 13A and 13B are longitudinal aberration diagrams at the wide-angle end and the telephoto end of the zoom lens of Example 5. [Figure 11] FIG. 13 is a cross-sectional view of a zoom lens of a sixth embodiment at a wide-angle end. [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 PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same reference numerals are given to the same members, and duplicated 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 when focused on infinity at the wide-angle end (infinity focused state). The zoom lenses of the examples are used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide 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 to have multiple lens groups. In this specification, a lens group is a group of lenses that move or stand still 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 the lens group may be configured of 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 denotes 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 is an aperture stop. IP is an image plane, and when the zoom lens of each embodiment is used as the photographing optical system of a digital still camera or digital video camera, the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed thereon. When the zoom lens of each embodiment is used as the photographing optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is disposed on the image plane IP.

[0015] In the zoom lens of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group moves in the direction of the solid arrow. 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 that it can move in the optical axis direction due to the mechanism. In addition, in the zoom lens of each embodiment, when focusing from infinity to a close distance, each lens group moves in the direction of the dotted arrow.

[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 when focused on an object at infinity at the wide-angle end, respectively. 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 when focused on an object at infinity at the telephoto end, respectively.

[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 imaging angle (°).

[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 group L1 moves, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, and the distance between the third lens group L3 and the fourth lens group L4 decreases. 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 group L2 does not move during zooming. This reduces the amount of relative decentering error between the first lens group L1 and the second lens group L2, making it possible to suppress deterioration of optical performance.

[0020] In such a configuration, the movement amount of the fourth lens group L4 becomes large during zooming from the wide-angle end to the telephoto end, so it is important to appropriately set the lens configuration of the fourth lens group L4 in order to suppress the fluctuation of various aberrations. The fourth lens group L4 is composed of a positive lens (first lens) Gp and a lens (second lens) Ga with positive or negative refractive power, arranged in this order from the object side to the image side. That is, in the zoom lens of each embodiment, the fluctuation of 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 is 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 formula (1) specifies the overall length of the zoom lens at the telephoto end and the focal length of the zoom lens at the telephoto end. By setting these conditions appropriately, it becomes easy to make the zoom lens compact. If the lower limit of conditional formula (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, which is undesirable as it becomes difficult to suppress the fluctuation of various aberrations that accompany zooming. If the upper limit of conditional formula (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 undesirable as it becomes difficult to make the zoom lens compact.

[0024] Conditional formula (2) specifies the refractive index of the lens Ga. Generally, the higher the refractive index of a lens, the higher its specific gravity. If the refractive index of the lens Ga is lowered below the lower limit of conditional formula (2), the curvature of the lens surface becomes stronger 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 accompany zooming. If the refractive index of the lens Ga is higher than the upper limit of conditional formula (2), the specific gravity of the lens Ga becomes larger, which is undesirable because it becomes difficult to reduce the weight of the zoom lens.

[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 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 further preferable that the numerical ranges of the conditional expressions (1) and (2) be 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, a description will be given of configurations that are preferably satisfied in the zoom lens of each embodiment.

[0029] It is preferable that the first lens unit L1 with positive refractive power, which is closest to the object, moves toward the object during zooming from the wide-angle end to the telephoto end, thereby making it possible to shorten the overall length of the zoom lens at the wide-angle end and to make the zoom lens more compact.

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

[0032] The lens group arranged on the image side of the aperture diaphragm SP tends to have a small effective diameter of the light beam. Therefore, if the lens group arranged on the image side of the aperture diaphragm SP is used as the focusing lens group, the holding mechanism and the driving mechanism can be simplified and the zoom lens can be easily made compact. Furthermore, if the focusing lens group is composed of two or less lenses, the focusing lens group can be easily made lighter. In addition, since the magnification change is relatively small on the image side of the aperture diaphragm SP, the change in image magnification can be reduced 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 reduced, allowing video shooting to be performed appropriately.

[0033] The effect of reducing camera shake can be obtained by driving all or part of any of the lens groups in a direction perpendicular to the optical axis direction. In particular, it is preferable to use the second lens group L2, which is fixed during zooming, as the camera shake correction lens group. With this configuration, the amount of movement of the camera shake correction lens group can be reduced and compactness can be easily achieved.

[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 of the positive lens Gp for the d line. νdL1Pave. is the average value of the Abbe numbers of the positive lenses included in the first lens group L1 for the d line. 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 formula (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 is increased below the lower limit of conditional formula (3), the refractive power of the lens Ga is weakened, which is undesirable because it becomes difficult to suppress the fluctuation of various aberrations such as spherical aberration and curvature of field that accompany zooming. If the focal length of the lens Ga is decreased above the upper limit of conditional formula (3), the refractive power of the fourth lens group L4 is weakened, which is undesirable because the amount of movement of the fourth lens group L4 that accompanies zooming becomes long.

[0037] Conditional formula (4) specifies the specific gravity of the lens Ga. Generally, as the specific gravity of a lens increases, the refractive index increases. 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 accompany zooming. If the specific gravity of the lens Ga increases above the upper limit of conditional formula (4), it is undesirable because it becomes difficult to reduce the weight of the zoom lens.

[0038] Conditional formula (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 amount of movement of the fourth lens group L4 falls below the lower limit of conditional formula (5) and becomes small, it becomes difficult to achieve a high zoom ratio, which is undesirable. If the amount of movement of the fourth lens group L4 exceeds the upper limit of conditional formula (5) and becomes large, it becomes difficult to make the zoom lens compact, which is undesirable.

[0039] Conditional formula (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 is long below the lower limit of conditional formula (6), the amount of movement of the first lens group L1 during zooming from the wide-angle end to the telephoto end becomes large, which is undesirable as it makes it difficult to reduce the size of the zoom lens. If the focal length of the first lens group L1 is short above the upper limit of conditional formula (6), it is undesirable as it makes it difficult to correct spherical aberration generated in the first lens group L1.

[0040] Conditional expression (7) defines the focal length of the zoom lens at the telephoto end and the focal length of the fourth lens group L4. If the focal length of the fourth lens group L4 is shortened below the lower limit of conditional expression (7), it is undesirable because it becomes difficult to suppress the fluctuation of various aberrations such as spherical aberration and curvature of field that accompanies zooming. If the focal length of the zoom lens at the telephoto end is shortened above the upper limit of conditional expression (7), it is undesirable because it becomes difficult to achieve a high zoom ratio.

[0041] Conditional formula (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 is shortened below the lower limit of conditional formula (8), it is difficult to suppress the fluctuation of various aberrations such as spherical aberration and curvature of field that accompany zooming, which is undesirable. If the focal length of the fourth lens group L4 is lengthened above the upper limit of conditional formula (8), the refractive power of the fourth lens group L4 is weakened, and the amount of movement of the fourth lens group L4 that accompanies zooming is increased, which is undesirable.

[0042] Conditional formula (9) defines the focal length of the third lens group L3 and the focal length of the fourth lens group L4. If the focal length of the fourth lens group L4 is shortened below the lower limit of conditional formula (9), it is difficult to suppress the fluctuation of various aberrations such as spherical aberration and curvature of field caused by zooming, which is not preferable. If the focal length of the fourth lens group L4 is lengthened above the upper limit of conditional formula (9), the refractive power of the fourth lens group L4 is weakened, and the amount of movement of the fourth lens group L4 caused by zooming is increased, which is not preferable.

[0043] Conditional formula (10) specifies 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 formula (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 exceeds the upper limit of conditional formula (10) and becomes large, it becomes difficult to correct axial chromatic aberration at the wide-angle end, which is undesirable.

[0044] Conditional expression (11) specifies the average value of the Abbe numbers of the positive lenses included in the first lens group L1 for the d-line. If the average value of the Abbe numbers of the positive lenses included in the first lens group L1 for the d-line becomes small below the lower limit of conditional expression (11), it becomes difficult to correct the axial chromatic aberration and the chromatic aberration of magnification at the telephoto end, which is not preferable. If the average value of the Abbe numbers of the positive lenses included in the first lens group L1 for the d-line becomes large above the upper limit of conditional expression (11), it becomes difficult to correct the chromatic aberration of magnification at the wide-angle end, which is not preferable.

[0045] Conditional expression (12) specifies the average value of the Abbe numbers of the positive lenses included in the third lens group L3 for the d-line. If the average value of the Abbe numbers of the positive lenses included in the third lens group L3 for the d-line becomes small below the lower limit of conditional expression (12), it becomes difficult to correct axial chromatic aberration at the telephoto end, which is not preferable. If the average value of the Abbe numbers of the positive lenses included in the third lens group L3 for the d-line becomes large above the upper limit of conditional expression (12), it becomes difficult to correct axial chromatic aberration at the wide-angle end, which is not preferable.

[0046] It is preferable that the numerical ranges of the conditional expressions (3) to (12) be 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 further 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 the first and second embodiments are composed 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, and 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 the fourth 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, 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, and negative refractive powers.

[0053] The zoom lens of the sixth embodiment 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 the first to sixth embodiments, respectively, are given 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. Additionally, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. The Abbe number νd of a certain material is given by the following, when 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 are Nd, NF, and NC, respectively: 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 surface expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the foremost lens surface (the lens surface closest to the object) to the final surface of the zoom lens 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 aspheric, a * symbol is added to the right of the surface number. The aspheric shape is expressed as follows, where X is the displacement from the apex 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 aspheric 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 aspheric coefficient is "×10± XX " It 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-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 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-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-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 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-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 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-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-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 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 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 the first to sixth embodiments. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built into the camera body and receives an optical image formed by the imaging optical system 11 and photoelectrically converts it. The camera body 10 may be a so-called single-lens reflex camera having a quick-turn mirror, or may be 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, it is possible to obtain an imaging device with a small lens. [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 blur correction. In this case, the control unit does not need to be configured integrally with the zoom lens, and the control unit may be configured separately from the zoom lens. For example, a configuration may be adopted in which a control unit (control device) that is disposed far away from a drive unit that drives each lens of the zoom lens includes a transmission unit that sends a control signal (command) for controlling the zoom lens. With such a control unit, the zoom lens can be remotely operated.

[0061] In addition, the control unit may be provided with an operation unit such as a controller or buttons for remotely operating the zoom lens, so that the zoom lens is controlled in response to a user's input to the operation unit. For example, a zoom-in button and a zoom-out button may be provided as the operation unit. In this case, the control unit may be configured to send a signal to a drive unit for the zoom lens so that the magnification of the zoom lens 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. The information related to the zoom of the zoom lens is, for example, the zoom magnification (zoom state) and 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 the operation unit may be integrated by adopting, 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 an object side to an image side, and 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 are 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; Let TLt be 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, ft be the focal length of the zoom lens at the telephoto end, and ndGa be the refractive index of the second lens, 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. Let ML1 be the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end, and ML4 be the amount of movement of the fourth lens group during zooming from the wide-angle end to the telephoto end, 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, which satisfies the following condition:

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, which satisfies the following condition:

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, which satisfies the following condition:

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, which satisfies the following condition:

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, which satisfies the following condition:

9. When the average Abbe number for the d-line of the material of the positive lenses included in the first lens group is νdL1Pave., 55<νdL1Pave. <99 9. The zoom lens according to claim 1, which satisfies the following condition:

10. When the average Abbe number 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, which satisfies the following condition:

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. 13. The zoom lens according to claim 1, wherein at least one of the lens surfaces of the first lens and the second lens is aspheric.

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 is provided, 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