Zoom lens and image pickup apparatus having the same

Abstract

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

Description

[Technical Field]

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

[0002] Wide-angle lenses are widely used for landscape photography, astronomical photography, etc. Wide-angle lenses are required to achieve high optical performance while widening the angle of view.

[0003] Patent Document 1 discloses a zoom lens that has a wide angle of view and high performance by employing a plurality of negative lenses in the first lens group to gently bend off-axis rays. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-203734 Summary of the Invention [Problem to be solved by the invention]

[0005] In the zoom lens described in Patent Document 1, because the aperture angle of the first lens is large, unwanted light reflected obliquely from the object-side lens surface of the second lens is reflected from the image-side lens surface of the first lens and can reach the image plane. If such unwanted light reaches the image plane, it can undesirably cause ghosts on the photograph.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a zoom lens that has high optical performance and is capable of reducing the occurrence of ghosts. [Means for solving the problem]

[0007] A zoom lens of the present invention has two or more lens groups arranged in order from the object side to the image side: a first lens group with negative refractive power and a second lens group with positive refractive power, wherein the first lens group moves during zooming and the spacing between adjacent lens groups changes; wherein, of the negative lenses included in the first lens group, negative lens A arranged closest to the object side has a refractive index of 1.89 or more; the first lens group has lens B arranged adjacent to the image side of negative lens A and a biconvex lens; and wherein, when the radius of curvature of the image side lens surface of negative lens A is Ra, the radius of curvature of the object side lens surface of lens B is Rb, the air spacing between negative lens A and lens B is Da, and the air spacing between lens B and the lens arranged adjacent to the image side of lens B is Db, 2.0 <Ra / Da<100 10 <Rb / Db<100 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a zoom lens that has high optical performance and can reduce the occurrence of ghosts. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a lens cross-sectional view of a zoom lens according to a first embodiment. [Figure 2] 3A to 3C are aberration diagrams of the zoom lens of Example 1. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens according to a second embodiment. [Figure 4] 10A to 10C are aberration diagrams of the zoom lens of Example 2. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens according to a third embodiment. [Figure 6] 10A to 10C are aberration diagrams of the zoom lens of Example 3. [Figure 7] FIG. 10 is a cross-sectional view of a zoom lens according to a fourth embodiment. [Figure 8] 10A to 10C are aberration diagrams of the zoom lens of Example 4. [Figure 9]FIG. 10 is a cross-sectional view of a zoom lens according to a fifth embodiment. [Figure 10] 10A to 10C are aberration diagrams of the zoom lens of Example 5. [Figure 11] FIG. 10 is a cross-sectional view of a zoom lens according to a sixth embodiment. [Figure 12] 10A to 10C are aberration diagrams of the zoom lens of Example 6. [Figure 13] FIG. 1 is a schematic diagram showing an imaging device. [Figure 14] FIG. 2 is a schematic diagram showing the optical path of unwanted light. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a zoom lens and an image pickup apparatus having the same according to the present invention will be described with reference to the accompanying drawings.

[0011] 1, 3, 5, 7, 9, and 11 are cross-sectional views of the zoom lens L0 of Examples 1 to 6, respectively. The zoom lens L0 of each Example is a zoom lens used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras using silver halide film, surveillance cameras, and vehicle-mounted cameras.

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

[0013] The zoom lens L0 of each embodiment has two or more lens groups arranged in order from the object side to the image side: a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, and so on. In each cross-sectional view, Li represents the i-th lens group counting from the object side (i is a natural number). In this specification, a lens group refers to a group of lenses that move or remain stationary as a unit during zooming. In other words, the spacing between adjacent lens groups changes during zooming. Each lens group may be composed of a single lens or multiple lenses. Each lens group may also include an aperture stop.

[0014] The arrows shown in each lens cross section indicate the movement locus during zooming from the wide-angle end to the telephoto end, and the movement locus during focusing from infinity to a close distance.

[0015] In each lens cross-sectional view, SP denotes an aperture stop. IP denotes an image plane, where 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 in a digital still camera or digital video camera. When the zoom lens of each embodiment is used as a photographic zoom lens for a silver halide film camera, a photosensitive surface equivalent to the film surface is placed on the image plane IP.

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

[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, S shows the amount of aberration on the sagittal image plane, and M shows the amount of aberration 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 of magnification 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] In the zoom lenses of each embodiment, the refractive power of the first lens unit L1 is made negative, thereby moving the entrance pupil closer to the object and reducing the diameter of the front lens (the lens located closest to the object). Furthermore, the refractive power of the second lens unit L2 is made positive, thereby converging on-axis marginal rays diverged by the first lens unit L1 and reducing the diameters of the second lens unit L2 and subsequent lens units. Furthermore, by providing two or more lens units on the image side of the positive second lens unit L2 and moving the first lens unit L1 during zooming, aberrations are effectively corrected over a wide zoom range.

[0020] Furthermore, in the zoom lens L0 of each embodiment, the refractive index of the negative lens A, which is the negative lens closest to the object side among the negative lenses in the first lens unit L1, is set to 1.89 or more. In addition, the lens is configured to satisfy the following conditional expressions: where Ra is the radius of curvature of the image-side lens surface of negative lens A. Rb is the radius of curvature of the object-side lens surface of lens B, which is arranged adjacent to the image side of negative lens A. Da is the air spacing between negative lens A and lens B. Db is the air spacing between lens B and the lens arranged adjacent to the image side of lens B. 2.0 <Ra / Da<100 (1) 10 <Rb / Db<100 (2) In wide-angle lenses, the diameter of the first lens, which is located closest to the object in the first lens group, tends to be large, and the aperture angle tends to be large. In this case, as shown in Figure 14, light reflected from the object-side lens surface of the second lens, which is located on the image side of the first lens, may be further reflected from the image-side lens surface of the first lens, forming an optical path that reaches the image plane. In this case, because both the first and second reflections are oblique reflections with respect to the lens surface, the reflection intensity is relatively high, making it easy for ghosts to become noticeable.

[0021] Therefore, in the zoom lens L0 of each embodiment, the refractive index of the negative lens A is set to 1.89, thereby providing the necessary refractive power to the negative lens A while relaxing the open angle. Also, by relaxing the curvature of the image-side lens surface of the negative lens A and the curvature of the object-side lens surface of lens B within a range that satisfies conditional expressions (1) and (2), off-axial light rays are reflected at an angle close to perpendicular to the lens surface, thereby suppressing the intensity of ghosts. Note that exceeding the upper limits of conditional expressions (1) and (2) is not preferable because it becomes difficult to provide the necessary refractive power to the negative lens A and lens B.

[0022] With the above configuration, it is possible to realize a zoom lens that has high optical performance and can reduce the occurrence of ghosts.

[0023] It is preferable that at least one of the upper limit and lower limit of the numerical range of either conditional expression (1) or (2) satisfies the range of the following conditional expression (1a) or (2a). 2.3 <Ra / Da<50 (1a) 11 <Rb / Db<50 (2a) It is even more preferable that at least one of the upper limit value or the lower limit value of the numerical range of either conditional formula (1) or (2) is set to the range of the following conditional formula (1b). 2.6 <Ra / Da<10 (1b) 11.5 <Rb / Db<30 (2b) By setting the refractive index of the negative lens A to a value greater than 1.89, it is possible to make the open angle of the negative lens A more favorable from the viewpoint of reducing ghosts.

[0024] Next, a preferred configuration of the zoom lens L0 in each embodiment will be described.

[0025] It is preferable that lens B, which is arranged adjacent to the image side of negative lens A, is a negative lens. With this configuration, a negative lens is arranged continuously with negative lens A, making it possible to gently bend off-axis rays. This makes it possible to effectively reduce astigmatism and field curvature, particularly at the wide-angle end.

[0026] It is also preferable that the first lens unit L1 be composed of three negative lenses and a positive lens arranged in that order from the object side to the image side. By arranging three negative lenses in succession, it is possible to further reduce astigmatism and curvature of field at the wide-angle end. Furthermore, by arranging a positive lens closest to the image side, it is possible to further reduce chromatic aberration of magnification, especially at the wide-angle end. Next, the conditional expressions that are preferably satisfied in the zoom lens L0 of each embodiment will be described.

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

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

[0029] If the lower limit of conditional expression (3) is not reached, the open angle required to provide the desired refractive power to lens B becomes large, which is undesirable because reflections on the object-side lens surface of lens B in particular become problematic.

[0030] Conditional expression (4) represents the ratio of the distance from the image-side lens surface of negative lens A at the wide-angle end to the aperture stop SP to the focal length of the entire system at the wide-angle end. If the upper limit is exceeded, the distance from the image-side lens surface of negative lens A at the wide-angle end to the aperture stop SP will be too long, making negative lens A likely to become large. If the lower limit is not reached, it will be difficult to sufficiently suppress the intensity of ghosts caused by unwanted light reflected between negative lens A and lens B.

[0031] Conditional expression (5) represents the ratio of the distance from the image-side lens surface of lens B at the wide-angle end to the aperture stop SP to the focal length of the entire system at the wide-angle end. If the upper limit is exceeded, the distance from the image-side lens surface of lens B at the wide-angle end to the aperture stop SP will be too long, making lens B likely to become large. If the lower limit is not reached, it will be difficult to sufficiently suppress the intensity of ghosts caused by unwanted light reflected between negative lens A and lens B.

[0032] Conditional expression (6) represents the ratio of the distance from the lens surface closest to the object in the first lens group L1 to the lens surface closest to the image to the distance from the lens surface closest to the object in the entire system to the paraxial image plane at the wide-angle end. If the upper limit is exceeded, the distance from the lens surface closest to the object in the first lens group L1 to the lens surface closest to the image becomes too long, resulting in a long distance from the aperture stop SP to the first lens (the lens positioned closest to the object). This results in a large first lens. If the lower limit is not exceeded, the distance from the lens surface closest to the object in the entire system to the paraxial image plane at the wide-angle end becomes too long, resulting in a large zoom lens L0.

[0033] Conditional expression (7) expresses the distortion rate at the wide-angle end. The ideal image height y0 is calculated by f × tan θ, where f is the focal length of the entire system at the wide-angle end, and θ is the angle (half angle of view) between the optical axis and the ray of light incident from the object side corresponding to the maximum real image height y and the entire system's closest point. The real image height y can be determined by the maximum radius of the image circle of the zoom lens L0. If the upper limit is exceeded, the refractive power of the first lens unit L1 must be reduced to reduce the absolute value of the distortion rate. This increases the distance from the lens surface closest to the object to the image plane IP, making the zoom lens L0 more bulky. If the lower limit is exceeded, the absolute value of the distortion rate becomes too large, significantly compressing the peripheral areas of the image, making it difficult to obtain images of sufficiently high image quality.

[0034] Conditional expression (8) represents the ratio of the focal length of the first lens unit L1 to the focal length of the entire system at the wide-angle end. If the upper limit is exceeded, the absolute value of the focal length of the first lens unit L1 becomes too short, resulting in excessively strong refractive power, which undesirably increases astigmatism, curvature of field, and chromatic aberration of magnification at the wide-angle end. If the lower limit is exceeded, the absolute value of the focal length of the first lens unit L1 becomes too long, which increases the distance from the lens surface closest to the object to the image plane IP and results in an increase in size.

[0035] Conditional expression (9) represents the ratio of the focal length of negative lens A to the focal length of the entire system at the wide-angle end. If the upper limit is exceeded, the absolute value of the focal length of negative lens A becomes too short, and the refractive power becomes too strong, resulting in large chromatic aberration of magnification, particularly at the wide-angle end. If the lower limit is not reached, the absolute value of the focal length of negative lens A becomes too long, and the distance from the lens surface closest to the object to the image plane IP becomes long, resulting in a large diameter of negative lens A.

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

[0037] Condition (11) defines the zoom ratio. If the upper limit is exceeded, the amount of movement of each lens group tends to increase, and the zoom lens L0 tends to become larger in size in order to secure space for the movement. If the lower limit is not reached, the zoom ratio becomes too small, making it difficult for the zoom lens to function satisfactorily.

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

[0039] [Example 1] The zoom lens L0 of Example 1 is composed of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with positive refractive power. By alternating the lens groups with negative refractive power and positive refractive power, lateral color and axial chromatic aberration are appropriately corrected. Furthermore, by making the fifth lens group L5 positive, a wide angle of view is achieved while ensuring a sufficient back focus, and ghosting caused by unwanted light reflected between the image plane IP (or a low-pass filter or IR cut filter that may be arranged on the object side thereof) and the fifth lens group L5 can be suppressed. Furthermore, the third lens group L3 is configured to move during focusing, and the object side of the third lens group L3 has a concentric shape, with a concave surface relative to the aperture stop SP. As a result, even when the third lens unit L3 moves during focusing, fluctuations in field curvature and astigmatism are suppressed, enabling high performance across the entire image field. Furthermore, by configuring the third lens unit L3 with two lenses, a positive lens and a negative lens, it is possible to suppress fluctuations in lateral chromatic aberration and axial chromatic aberration even when the third lens unit L3 moves in the optical axis direction.

[0040] In addition, the first lens group is designed to move monotonically toward the image side during zooming from the wide-angle end to the telephoto end, which increases the absolute value of the focal length of the first lens group (weakens the refractive power) and improves the performance of the zoom lens L0.

[0041] [Example 2] In Example 2, the third lens unit L3, which is the focusing unit, is configured with one negative lens, unlike Example 1. This makes it possible to reduce the size of the third lens unit L3, which moves during focusing.

[0042] [Example 3] The zoom lens L0 of Example 3 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with negative refractive power, a second lens unit L2 with positive refractive power, a third lens unit L3 with negative refractive power, a fourth lens unit L4 with negative refractive power, and a fifth lens unit L5 with positive refractive power. By making the fourth lens unit L4 have negative refractive power, chromatic aberration of magnification that occurs in the fifth lens unit L5 with positive refractive power can be effectively corrected. In addition, by locating a positive lens closest to the object side, negative distortion that occurs in the first lens unit L1 is reduced, and by suppressing distortion, compression at the periphery of the image is suppressed, thereby improving resolution.

[0043] In addition, by cementing the fourth and fifth lenses together, the intensity of unwanted light reflected between the fourth and fifth lenses is reduced, suppressing ghosting.

[0044] Furthermore, by moving the fifth lens unit L5 toward the object side toward the telephoto end, it is possible to position the fifth lens unit L5 at a position where the height of off-axial rays is low at the telephoto end, thereby reducing the diameter.

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

[0046] [Example 5] The zoom lens L0 of Example 5 is composed of, arranged in order from the object side to the image side, a first lens unit L1 with negative refractive power, a second lens unit L2 with positive refractive power, a third lens unit L3 with negative refractive power, a fourth lens unit L4 with positive refractive power, and a fifth lens unit L5 with negative refractive power. By making the fourth lens unit L4 positive and the fifth lens unit L5 negative refractive power, the position of the combined front principal point of the fourth lens unit L4 and the fifth lens unit L5 can be moved toward the object side, shortening the back focal length and enabling the zoom lens L0 to be made more compact.

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

[0048] The zoom lens L0 of each of the above-described embodiments may be used in an imaging device having an image processing function for correcting aberrations (distortion aberration and chromatic aberration of magnification).

[0049] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below.

[0050] 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 at the d-line, and vd represents the Abbe number of the optical element. The Abbe number vd of a certain material is given by Nd, NF, NC, and Ng, respectively, when the refractive indices at the Fraunhofer d-line (587.6 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.8 nm) are Nd, NF, NC, and Ng, respectively. νd=(Nd-1) / (NF-NC) It is expressed as:

[0051] 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 a direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, A10, A12, ... are the aspherical coefficients of each order. x=(h 2 / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 ]+A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means.

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

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

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

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

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

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

[0058] [Table 1]

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

[0060] Reference numeral 12 denotes a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body and receives and photoelectrically converts the optical image formed by the lens device 11. The camera body 10 may be a so-called single-lens reflex camera that has a quick-turn mirror, or a so-called mirrorless camera that does not have a quick-turn mirror.

[0061] In this way, by applying the zoom lens L0 of the present invention to an imaging device such as a digital still camera, it is possible to obtain high-quality images with low aberration and reduced occurrence of ghosts.

[0062] 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]

[0063] L0 zoom lens L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group L5 Fifth lens group L6 6th lens group

Claims

1. A zoom lens having two or more lens groups, arranged in order from the object side to the image side, a first lens group having negative refractive power, a second lens group having positive refractive power, and the first lens group moving during zooming to change the spacing between adjacent lens groups, Among the negative lenses included in the first lens group, the negative lens A located closest to the object side has a refractive index of 1.89 or more, the first lens group includes a lens B disposed adjacent to the image side of the negative lens A, and a biconvex lens, Let Ra be the radius of curvature of the image-side lens surface of the negative lens A, Rb be the radius of curvature of the object-side lens surface of the lens B, Da be the air gap between the negative lens A and the lens B, and Db be the air gap between the lens B and the lens disposed adjacent to the image side of the lens B. 2.0<Ra / Da<100 10<Rb / Db<100 A zoom lens characterized by satisfying the following conditional expressions:

2. When the refractive index of the lens B is N dB, 1.80<NdB 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. an aperture stop; When the distance from the image-side lens surface of the negative lens A at the wide-angle end to the aperture stop is d and the focal length of the zoom lens at the wide-angle end is fw, 2.0<d / fw<15 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. having an aperture stop, When the distance from the image-side lens surface of the lens B at the wide-angle end to the aperture stop is d2 and the focal length of the zoom lens at the wide-angle end is fw, 1.5<d2 / fw<5.0 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. Let GL be the distance from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image side, and TL be the distance from the lens surface of the zoom lens closest to the object side to the image plane at the wide-angle end. 0.15<GL / TL<0.30 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the maximum real image height at the wide-angle end is y and the ideal image height of the maximum angle of view of the zoom lens at the wide-angle end is y0, -20<100×(y-y0) / y0<-8 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the first lens group is f1 and the focal length of the zoom lens at the wide-angle end is fw, -2.5<f1 / fw<-0.8 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. When the focal length of the negative lens A is fa and the focal length of the zoom lens at the wide-angle end is fw, -3.5<fa / fw<-1.5 8. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. 9. The zoom lens according to claim 1, wherein the lens B is a negative lens.

10. When the focal length of the lens B is fb and the focal length of the zoom lens at the wide-angle end is fw, -3.5<fb / fw<-0.8 10. The zoom lens according to claim 9, wherein the following condition is satisfied:

11. When the focal length of the zoom lens at the telephoto end is ft and the focal length of the zoom lens at the wide-angle end is fw, 1.2<ft / fw<2.1 11. The zoom lens according to claim 1, wherein the following condition is satisfied:

12. 12. The zoom lens according to claim 1, wherein the first lens group is made up of three negative lenses and a positive lens disposed on the image side of the three negative lenses.

13. 13. The zoom lens according to claim 1, wherein the zoom lens has a lens group with positive refractive power closest to the image side.

14. 13. The zoom lens according to claim 1, wherein the zoom lens has a lens group with negative refractive power closest to the image side.

15. 15. An imaging device comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens.

Images