Zoom lens and imaging apparatus
The zoom lens configuration with a stationary first lens group and optimized intermediate lens group addresses the need for a smaller, higher zoom ratio lens by enhancing aberration correction and zoom performance.
Patent Information
- Application Number
- JP2024110438
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-09
- Publication Date
- 2026-01-22
Smart Images
Figure 2026010518000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a zoom lens and an imaging device. [Background technology]
[0002] 2. Description of the Related Art Conventionally, a zoom lens has been known that is made up of lens groups having, in order from the object side to the image side, negative, positive, negative, positive, negative, and positive refractive powers. Summary of the Invention [Problem to be solved by the invention]
[0003] There is a demand for a zoom lens that is smaller than conventional ones and has a higher zoom ratio. [Means for solving the problem]
[0004] One aspect of the present invention provides a zoom lens comprising, 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, an intermediate lens group, and a rear lens group, wherein the intermediate lens group comprises, in order from the object side to the image side, a third lens group having negative refractive power and a fourth lens group having positive refractive power, and the rear lens group comprises, in order from the object side to the image side, a fifth lens group having negative refractive power and a sixth lens group having positive refractive power, or comprises the fifth lens group having negative refractive power, and during zooming from the wide-angle end to the telephoto end, the first lens group remains stationary and the spacing between adjacent lens groups changes, and the intermediate lens group has five or more lenses, and satisfies a predetermined conditional expression.
[0005] Other objects and features of the present invention are illustrated in the following examples. [Brief explanation of the drawings]
[0006] [Figure 1] FIG. 1 is a cross-sectional view of a zoom lens at a wide-angle end in a first embodiment. [Figure 2] 3A to 3C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 1. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end in a second embodiment. [Figure 4] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 2. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 3. [Figure 6] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 3. [Figure 7] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 4. [Figure 8] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 4. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end in Example 5. [Figure 10] 10A to 10C are aberration diagrams of the zoom lens at the wide-angle end, at the intermediate zoom position, and at the telephoto end in Example 5. [Figure 11] FIG. 1 is a diagram illustrating the configuration of an imaging device equipped with a zoom lens in each embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0008] The zoom lens L0 in each embodiment is a zoom lens used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and vehicle-mounted cameras.
[0009] 1, 3, 5, 7, and 9 are cross-sectional views of the zoom lens L0 of Examples 1 to 5 at the wide-angle end when focusing on infinity. In each cross-sectional view, the left side is the object side and the right side is the image side. The zoom lens L0 of each Example may be used as a projection lens for a projector or the like. In this case, the left side is the screen side (enlargement side) and the right side is the projected image side (reduction side).
[0010] In each cross-sectional view, L1 is the first lens group, L2 is the second lens group, L3 is the third lens group, L4 is the fourth lens group, L5 is the fifth lens group, and L6 is the sixth lens group. When changing magnification (zooming) from the wide-angle end to the telephoto end, each lens group moves as shown by the arrows in each diagram. The solid and dotted arrows indicate the movement trajectories when focusing on an object at infinity and a close distance, respectively.
[0011] In each cross-sectional view, P denotes a glass block such as a CCD faceplate or low-pass filter. I denotes an image plane. When the zoom lens L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera, the imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed on the image plane I. When the zoom lens L0 of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is placed on the image plane I.
[0012] In each cross-sectional view, SP denotes an aperture stop. The aperture stop SP forms part of the third lens unit L3. During zooming, the aperture stop P moves together with the third lens unit L3. The aperture diameter of the aperture stop SP may be constant during zooming, or may be changed during zooming. By changing the diameter of the aperture stop SP, it is possible to cut out underline coma flare caused by off-axial light beams that occurs significantly at the telephoto end, thereby achieving better optical performance.
[0013] The zoom lens L0 in each embodiment is composed of, in order from the object side to the image side, a first lens group L1 having negative refractive power, a second lens group L2 having positive refractive power, an intermediate lens group, and a rear lens group, and has a configuration suitable for use as a wide-angle zoom lens.
[0014] The intermediate lens group has a lens group with positive refractive power closest to the image side. The intermediate lens group is composed of a lens group with negative refractive power and a lens group with positive refractive power, or is composed of a lens group with positive refractive power. This configuration makes it possible to correct image plane fluctuations during zooming and suppress fluctuations in various aberrations.
[0015] The rear lens group has a lens group with negative refractive power closest to the object. The rear lens group is composed of a lens group with negative refractive power and a lens group with positive refractive power, or is composed of a lens group with negative refractive power. This configuration allows the second lens group L2 and the intermediate lens group to move together during zooming, making it possible to efficiently achieve a large zoom ratio.
[0016] During zooming from the wide-angle end to the telephoto end, the first lens group is immobile (fixed), and the heavy first lens group L1 is not moved.
[0017] The intermediate lens group has five or more lenses, and can suppress fluctuations in various aberrations, particularly spherical aberration and coma, that occur during zooming.
[0018] Here, the amount of movement of the second lens unit L2 from the wide-angle end to the telephoto end is m2, and the amount of movement of the third lens unit L3 from the wide-angle end to the telephoto end is m3, and the sign of the amount of movement is positive when the lens unit is located closer to the image at the telephoto end than at the wide-angle end. In this case, in each embodiment, it is preferable to satisfy the following conditional expression (1):
[0019] 0.60 <m2 / m3<2.10 ···(1) Conditional formula (1) defines the ratio of the movement amount of the second lens unit L2 to the movement amount of the third lens unit L3 from the wide-angle end to the telephoto end. Exceeding the upper limit of conditional formula (1) is undesirable because it becomes difficult to suppress fluctuations in various aberrations, particularly spherical aberration and coma, that occur during zooming. On the other hand, falling below the lower limit of conditional formula (1) is undesirable because it becomes difficult to efficiently achieve a desired zoom ratio.
[0020] More preferably, the upper limit of conditional expression (1) is set to 2.00, 1.92, 1.84, 1.76, 1.64, 1.56, or 1.50, and more preferably, the lower limit of conditional expression (1) is set to 0.62, 0.64, 0.66, 0.69, or 0.72.
[0021] Here, the maximum Abbe number, based on the d-line, of the negative lenses in the lens group having positive refractive power included in the intermediate lens group (third lens group L3 (FIGS. 7 and 9) or fourth lens group L4 (FIGS. 1, 3, and 5)) is denoted by νm. In this case, in each embodiment, it is preferable to satisfy the following conditional expression (2):
[0022] 28.0<νm (2) Conditional formula (2) defines the maximum Abbe number, based on the d-line, of the negative lenses in the lens group with positive refractive power included in the intermediate lens group. If the lower limit of conditional formula (2) is not met, it becomes difficult to correct both the chromatic aberration at the wide-angle end and the axial chromatic aberration at the telephoto end, which is undesirable.
[0023] More preferably, the lower limit of conditional expression (2) is set to 29.0, 30.0, 31.0, 32.0, or 33.0, and the upper limit of conditional expression (2) is set to 95.0, 92.0, 89.0, 85.0, or 82.0.
[0024] In each embodiment, it is preferable that the first lens unit L1 has three or more lenses, which makes it possible to effectively correct curvature of field at the wide-angle end and spherical aberration at the telephoto end.
[0025] In each embodiment, when the focal length of the lens unit having negative refractive power included in the rear lens unit is fr and the focal length of the first lens unit L1 is f1, it is preferable to satisfy the following conditional expression (3).
[0026] 1.50 <fr / f1<6.00 ···(3) Conditional expression (3) defines the ratio between the focal length of the lens group having negative refractive power included in the rear lens group and the focal length of the first lens group L1. Exceeding the upper limit of conditional expression (3) tends to increase the distance from the object side surface of the rear lens group to the image plane, which is undesirable from the viewpoint of shortening the overall length. On the other hand, falling below the lower limit of conditional expression (3), the refractive power of the lens group having positive refractive power adjacent to the lens group having negative refractive power included in the rear lens group tends to become stronger in order to maintain the focal length of the entire zoom lens L0. As a result, it becomes difficult to suppress fluctuations in field curvature and chromatic aberration of magnification that occur during zooming, which is undesirable.
[0027] More preferably, the upper limit of conditional expression (3) is set to 5.95, 5.91, 5.85, 5.77, 5.71, or 5.65, and more preferably, the lower limit of conditional expression (3) is set to 1.53, 1.55, 1.57, 1.59, 1.61, or 1.63.
[0028] In each embodiment, when the focal length of the second lens unit L2 is f2, it is preferable to satisfy the following conditional expression.
[0029] -0.90 <f1 / f2<-0.45 ···(4) Conditional expression (4) defines the ratio between the focal length of the first lens unit L1 and the focal length of the second lens unit L2. Exceeding the upper limit of conditional expression (4) is undesirable because it becomes difficult to correct curvature of field at the wide-angle end and spherical aberration at the telephoto end. On the other hand, falling below the lower limit of conditional expression (4) is undesirable because it tends to increase the diameter of the front lens element.
[0030] More preferably, the upper limit of conditional expression (4) is set to −0.46, −0.47, or −0.48, and more preferably, the lower limit of conditional expression (4) is set to −0.89, −0.88, −0.87, −0.86, −0.85, or −0.84.
[0031] In each embodiment, when the zoom ratio is z, it is preferable to satisfy the following conditional expression (5).
[0032] 1.80 <z<5.00 ···(5) Conditional expression (5) defines the zoom ratio. Exceeding the upper limit of conditional expression (5) is undesirable because it becomes difficult to correct various aberrations while maintaining a compact size. On the other hand, falling below the lower limit of conditional expression (5) is undesirable within the scope of application of each embodiment.
[0033] More preferably, the upper limit of conditional expression (5) is set to 4.92, 4.85, 4.73, 4.60, 4.45, 4.21, 4.09, or 3.95, and more preferably, the lower limit of conditional expression (5) is set to 1.83, 1.87, 1.90, 1.92, 1.95, or 1.98.
[0034] In each embodiment, when the smallest Abbe number of the positive lens in the second lens unit L2 with reference to the d-line is ν2, it is preferable to satisfy the following conditional expression (6).
[0035] 25.0<ν2<53.0 (6) Conditional formula (6) defines the minimum Abbe number of the positive lens in the second lens group L2, based on the d-line. Exceeding the upper limit of conditional formula (6) is undesirable because it becomes difficult to correct chromatic aberration at the wide-angle end. On the other hand, falling below the lower limit of conditional formula (6) is undesirable because the Abbe number of the negative lens in the second lens group L2 also becomes small, and the lens tends to be made of a material with low transmittance on the short wavelength side.
[0036] More preferably, the upper limit of conditional expression (6) is set to 52.7, 52.1, 51.5, 50.9, 50.3, or 49.8, and the lower limit of conditional expression (6) is set to 25.5, 26.0, 26.5, 27.0, 27.5, 28.0, 28.5, 29.0, or 29.5.
[0037] In each embodiment, the second lens unit L2 preferably has three or more lenses. By having the second lens unit L2 have three or more lenses, it becomes possible to effectively correct spherical aberration and curvature of field on the telephoto side.
[0038] In each embodiment, it is preferable to satisfy the following conditional expression (7), where L is the total optical length of the zoom lens L0 and ft is the focal length of the entire system of the zoom lens L0 at the telephoto end. Note that the total optical length L is the total length of the zoom lens L0 plus the back focus. If a glass block or the like is present in the back focus, the increase in the back focus due to the glass block or the like is also added.
[0039] 2.00 <L / ft<6.00 ···(7) Conditional expression (7) defines the ratio between the total optical length and the focal length at the telephoto end. Exceeding the upper limit of conditional expression (7) is undesirable because the total optical length becomes too long. On the other hand, falling below the lower limit of conditional expression (7) is undesirable because it becomes difficult to correct spherical aberration and field curvature, especially at the telephoto end.
[0040] More preferably, the upper limit of conditional expression (7) is set to 5.95, 5.90, 5.85, 5.80, 5.75, 5.70, or 5.65, and more preferably, the lower limit of conditional expression (7) is set to 2.15, 2.23, 2.37, 2.55, 2.73, 2.81, or 2.85.
[0041] In each embodiment, it is preferable to satisfy the following conditional expression (8).
[0042] -7.50 <L / m2<-3.00 ···(8) Conditional expression (8) defines the ratio between the total optical length and the amount of movement of the second lens unit L2 from the wide-angle end to the telephoto end. Exceeding the upper limit of conditional expression (8) is undesirable because it limits the amount of movement of the lens units other than the second lens unit L2 during zooming, making it difficult to suppress fluctuations in spherical aberration and field curvature that accompany zooming. On the other hand, falling below the lower limit of conditional expression (8) is undesirable because it increases the total optical length.
[0043] More preferably, the upper limit of conditional expression (8) is set to −3.05, −3.12, −3.18, −3.27, −3.30, or −3.34, and the lower limit of conditional expression (8) is set to −7.39, −7.25, −7.12, −6.98, −6.81, −6.89, or −6.80.
[0044] In each embodiment, when the focal length of the entire zoom lens system L0 at the wide-angle end is represented by fw, it is preferable to satisfy the following conditional expression (9):
[0045] -2.50 <f1 / fw<-1.30 ···(9) Conditional formula (9) defines the ratio between the focal length of the first lens unit L1 and the focal length of the zoom lens L0 at the wide-angle end. If the upper limit of conditional formula (9) is exceeded, the curvature of the lenses in the first lens unit L1 tends to become strong. To weaken the lens curvature, the number of lenses must be increased. In either case, the weight of the lens increases, which is undesirable. On the other hand, if the lower limit of conditional formula (9) is exceeded, the amount of movement of the second lens unit L2 tends to increase in order to maintain the zoom ratio, which leads to an increase in the overall length, which is undesirable.
[0046] More preferably, the upper limit of conditional expression (9) is set to −1.31, −1.32, −1.33, −1.34, −1.35, −1.36, −1.37, −1.38, or −1.39, and more preferably, the lower limit of conditional expression (9) is set to −2.42, −2.36, −2.28, −2.20, −2.14, −2.10, or −2.06.
[0047] Here, the distance on the optical axis OA between the first lens unit L1 and the second lens unit L2 at the telephoto end is D1t, and the distance on the optical axis OA between the first lens unit L1 and the second lens unit L2 at the wide-angle end is D1w. In this case, in each embodiment, it is preferable to satisfy the following conditional expression (10):
[0048] 0.00 <D1t / D1w<0.40 ···(10) Conditional expression (10) defines the ratio of the axial distance between the first lens group L1 and the second lens group L2 at the telephoto end to the axial distance between the first lens group L1 and the second lens group L2 at the wide-angle end. Exceeding the upper limit of conditional expression (10) is undesirable because it makes it difficult to efficiently achieve a high zoom ratio with the second lens group L2. On the other hand, falling below the lower limit of conditional expression (10) is undesirable because the lenses and holding members of the first lens group L1 and the second lens group L2 interfere with each other at the telephoto end.
[0049] More preferably, the upper limit of conditional expression (10) is set to 0.39, 0.38, 0.37, 0.36, 0.35, or 0.34, and more preferably, the lower limit of conditional expression (10) is set to 0.003, 0.005, 0.007, 0.010, or 0.012.
[0050] In each embodiment, by having the respective configurations as described above or by satisfying at least one of the conditional expressions, it is possible to obtain, for example, a compact, high-magnification, high-image-quality, wide-angle zoom lens. Furthermore, by arbitrarily combining a plurality of conditional expressions, the effects of each embodiment can be further enhanced.
[0051] The zoom lens L0 of Examples 1 to 3 (FIGS. 1, 3, and 5) comprises, in order from the object side to the image side, a first lens group L1 having negative refractive power, a second lens group L2 having positive refractive power, an intermediate lens group, and a rear lens group. The intermediate lens group comprises, in order from the object side to the image side, a third lens group L3 having negative refractive power and a fourth lens group L4 having positive refractive power. The rear lens group comprises, in order from the object side to the image side, a fifth lens group L5 having negative refractive power and a sixth lens group L6 having positive refractive power, or comprises the fifth lens group L5 having negative refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes.
[0052] The zoom lens L0 of Examples 4 and 5 (FIGS. 7 and 9) comprises, in order from the object side to the image side, a first lens group L1 having negative refractive power, a second lens group L2 having positive refractive power, an intermediate lens group, and a rear lens group. The intermediate lens group comprises a third lens group L3 having positive refractive power. The rear lens group comprises, in order from the object side to the image side, a fourth lens group L4 having negative refractive power and a fifth lens group L5 having positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes.
[0053] The zoom lens L0 of Examples 1 and 2 is composed of, in order from the object side to the image side, a first lens group L1, a second lens group L2, a third lens group L3, a fourth lens group L4, a fifth lens group L5, and a sixth lens group L6. The third lens group L3 and the fourth lens group L4 form an intermediate lens group. The fifth lens group L5 and the sixth lens group L6 form a rear lens group.
[0054] The zoom lens L0 of Example 3 is composed of, in order from the object side to the image side, a first lens group L1, a second lens group L2, a third lens group L3, a fourth lens group L4, and a fifth lens group L5. The third lens group L3 and the fourth lens group L4 form an intermediate lens group. The fifth lens group L5 forms a rear lens group.
[0055] The zoom lens L0 of Examples 4 and 5 is composed of, in order from the object side to the image side, a first lens group L1, a second lens group L2, a third lens group L3, a fourth lens group L4, and a fifth lens group L5. The third lens group L3 constitutes an intermediate lens group. The fourth lens group L4 and the fifth lens group L5 constitute a rear lens group.
[0056] 2, 4, 6, 8, and 10 are aberration diagrams of the zoom lens in Examples 1 to 5 when focused on infinity at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end, respectively.
[0057] In the spherical aberration diagram, Fno is the F-number, the solid line shows the amount of spherical aberration for the d-line (wavelength 587.6 nm), and the dashed line shows the amount of spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line shows the amount of aberration on the sagittal image plane, and the dashed line 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 lateral chromatic aberration for the g-line is shown. ω is the half angle of view (°).
[0058] Numerical Examples 1 to 5 corresponding to Examples 1 to 5, respectively, are shown below. In each numerical example, ri is the radius of curvature of the ith surface, in order from the object side, di is the distance between the ith surface and the (i+1)th surface (lens thickness or air distance), and ndi and νdi are the refractive index and Abbe number of the material of the ith lens at the d-line, respectively. Note that the Abbe number νd of a certain material is given by: where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines, respectively. νd=(Nd-1) / (NF-NC) It is expressed as:
[0059] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values when the zoom lens of each example is focused at infinity. BF (back focus) is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane expressed as an air-equivalent length, and is a value that does not include the glass block. The total lens length is the length from the surface (lens surface) of the zoom lens closest to the object to the image plane. The lens group is not limited to being composed of multiple lenses, and may be composed of a single lens.
[0060] (Numerical Example 1) Unit: mm Surface Data Surface number rd nd νd 1 77.069 1.72 1.89190 37.1 2 21.030 11.22 3 -48.639 1.30 1.49700 81.5 4 44.331 2.60 5 696.119 1.23 1.49700 81.5 6 35.156 6.80 1.90525 35.0 7 -56.309 1.26 8 -36.045 1.21 1.49700 81.5 9 86.697 (variable) 10 40.792 3.10 1.85025 30.1 11 -72.074 1.65 12 -78.527 0.82 1.96300 24.1 13 33.705 2.83 1.49700 81.5 14 -128.225 0.17 15 32.427 3.31 1.49700 81.5 16 -69.058 (variable) 17 -28.819 0.77 1.68893 31.1 18 69.010 1.55 1.95906 17.5 19 -281.734 2.00 20 (Aperture) ∞ (Variable) 21 18.639 4.58 1.49700 81.5 22 -54.719 1.32 23 62.529 1.13 1.49700 81.5 24 13.938 2.20 25 21.393 5.55 1.49700 81.5 26 -12.870 1.05 1.80440 39.6 27 -43.496 (variable) 28 -21.222 0.69 1.51633 64.1 29 87.617 0.89 1.95906 17.5 30 237.770 (variable) 31 43.986 3.27 1.49700 81.5 32 -74.149 7.60 33 ∞ 1.20 1.51633 64.1 34∞1.00 Image plane ∞ Various data Zoom ratio 3.90 Wide-angle Mid-range Telephoto Focal length 11.42 22.06 44.54 F-number 2.06 3.11 5.15 Half angle of view 57.50 27.80 13.70 Image height 10.75 10.75 10.75 Lens length 127.47 127.47 127.47 BF 9.39 9.39 9.39 d 9 38.73 19.62 0.50 d16 2.77 6.20 5.16 d20 3.61 4.36 2.00 d27 6.30 4.33 20.21 d30 2.47 19.37 26.02 Zoom lens group data Group starting plane focal length 1 1 -21.56 2 10 31.72 3 17 -60.78 4 21 37.09 5 28 -42.85 6 31 56.07 (Numerical Example 2) Unit: mm Surface Data Surface number rd nd νd 1 64.891 1.57 1.95375 32.3 2 17.472 7.39 3 112.945 1.18 1.49700 81.5 4 37.872 3.09 5 -260.640 1.12 1.49700 81.5 6 64.456 4.28 7 -35.332 1.15 1.49700 81.5 8 57.741 4.16 1.90525 35.0 9 -73.504 (variable) 10 60.130 1.49 1.92286 18.9 11 26.581 3.48 1.77250 49.6 12 -120.332 0.17 13 49.368 1.44 1.49700 81.5 14 171.311 0.17 15 34.892 3.16 1.49700 81.5 16 -63.687 (variable) 17 -30.772 0.67 1.77250 49.6 18 38.251 1.61 19 -49.272 0.69 1.89190 37.1 20 27.957 3.50 1.89286 20.4 21 -35.677 2.00 22 (Aperture) ∞ (Variable) 23 32.248 3.57 1.49700 81.5 24 -30.453 0.17 25 61.893 0.66 1.63980 34.5 26 15.683 3.22 1.49700 81.5 27 225.726 0.17 28 44.707 3.74 1.49700 81.5 29 -19.332 0.67 1.80518 25.4 30 -73.734 (variable) 31 -154.790 3.04 1.76182 26.5 32 -17.499 0.71 1.83481 42.7 33 37.640 (variable) 34 31.340 3.75 1.89190 37.1 35 -317.571 0.99 1.89286 20.4 36 27.614 3.76 1.62299 58.2 37 -886.820 7.60 38 ∞ 1.20 1.51633 64.1 39∞1.00 Image plane ∞ Various data Zoom ratio 3.00 Wide-angle Mid-range Telephoto Focal length 10.72 18.88 32.16 F-number 2.06 2.98 4.04 Half angle of view 58.00 32.10 18.80 Image height 10.75 10.75 10.75 Lens total length 127.46 127.46 127.46 BF 9.39 9.39 9.39 d 9 30.43 16.50 2.57 d16 4.76 6.84 9.30 d22 8.98 5.29 2.00 d30 4.73 2.35 6.57 d33 2.41 20.34 30.88 Zoom lens group data Group starting plane focal length 1 1 -19.15 2 10 23.23 3 17 -29.11 4 23 27.61 5 31 -31.67 6 34 50.00 (Numerical Example 3) Unit: mm Surface Data Surface number rd nd νd 1 127.165 1.72 1.83481 42.7 2 20.031 8.32 3 830.702 2.26 1.49700 81.5 4 44.366 10.85 5 -30.441 1.22 1.49700 81.5 6 197.521 3.54 1.90366 31.3 7 -57.252 (variable) 8 38.076 2.00 1.76200 40.1 9 189.284 8.23 10 92.271 0.81 1.85478 24.8 11 26.557 2.88 1.49700 81.5 12 -942.768 0.17 13 36.907 3.57 1.49700 81.5 14 -77.778 (variable) 15 -28.462 0.76 1.77250 49.6 16 41.590 1.99 2.00100 29.1 17 -371.781 2.00 18 (Aperture) ∞ (Variable) 19 18.913 4.96 1.49700 81.5 20 -56.005 2.09 21 58.961 0.62 1.77250 49.6 22 16.659 0.97 23 31.801 1.53 1.49700 81.5 24 382.942 0.17 25 23.339 4.37 1.49700 81.5 26 -13.617 0.60 1.79952 42.2 27 -41.677 (variable) 28 -41.785 2.07 1.72825 28.5 29 -17.398 0.68 1.77250 49.6 30 220.037 (variable) 31 ∞ 1.20 1.51633 64.1 32∞1.00 Image plane ∞ Various data Zoom ratio 3.00 Wide-angle Mid-range Telephoto Focal length 11.43 20.39 34.30 F-number 2.06 3.08 4.17 Half angle of view 57.30 30.20 17.80 Image height 10.75 10.75 10.75 Lens length 125.77 125.77 125.77 BF 9.75 24.83 36.97 d 7 33.74 17.12 0.50 d14 2.82 9.59 13.74 d18 2.35 3.49 2.00 d27 8.72 2.35 4.17 d30 7.96 23.04 35.18 Zoom lens group data Group starting plane focal length 1 1 -23.34 2 8 34.76 3 15 -53.19 4 19 29.78 5 28 -42.31 (Numerical Example 4) Unit: mm Surface Data Surface number rd nd νd 1 64.598 3.00 1.89190 37.1 2 18.941 10.94 3 -51.563 1.23 1.49700 81.5 4 37.848 3.23 5 -280.533 1.15 1.49700 81.5 6 30.201 6.66 1.90525 35.0 7 -58.323 1.52 8 -33.293 1.97 1.49700 81.5 9 101.119 (variable) 10 42.055 2.67 1.85025 30.1 11 -99.059 2.72 12 -111.823 0.79 1.96300 24.1 13 31.118 4.49 1.49700 81.5 14 -68.237 0.17 15 33.736 2.83 1.49700 81.5 16 -109.048 (variable) 17 -31.304 1.34 1.68893 31.1 18 54.316 2.22 1.95906 17.5 19 -2841.675 2.00 20 (Aperture) ∞ 3.64 21 20.142 4.48 1.49700 81.5 22 -57.018 1.50 23 34.656 1.20 1.49700 81.5 24 14.600 2.54 25 23.228 5.57 1.49700 81.5 26 -13.753 1.02 1.80440 39.6 27 -50.244 (variable) 28 -22.830 0.69 1.51633 64.1 29 100.859 1.12 1.95906 17.5 30 245.545 (variable) 31 55.765 4.27 1.49700 81.5 32 -41.722 8.47 33 ∞ 1.20 1.51633 64.1 34∞1.00 Image plane ∞ Various data Zoom ratio 2.00 Wide-angle Mid-range Telephoto Focal length 11.34 16.07 22.69 F-number 2.06 2.55 3.09 Half angle of view 57.20 38.80 27.30 Image height 10.75 10.75 10.75 Lens length 127.40 127.40 127.40 BF 10.26 10.26 10.26 d 9 30.53 20.42 10.30 d16 2.91 6.30 6.09 d27 6.27 5.71 9.65 d30 2.47 9.75 16.14 Zoom lens group data Group starting plane focal length 1 1 -19.11 2 10 33.07 3 17 59.02 4 28 -45.11 5 31 48.73 (Numerical Example 5) Unit: mm Surface Data Surface number rd nd νd 1 115.669 1.71 1.69680 55.5 2 19.847 9.83 3 -75.994 1.44 1.43700 95.1 4 34.947 3.43 5 -431.817 2.00 1.43700 95.1 6 20.749 9.46 1.67300 38.3 7 -65.120 1.95 8 -34.184 1.76 1.43700 95.1 9 38.148 (variable) 10 56.551 3.40 1.90525 35.0 11 -87.571 2.00 12 -46.935 1.13 1.76182 26.5 13 33.701 3.78 1.45650 90.3 14 -51.938 1.66 15 38.129 3.28 1.59522 67.7 16 -78.378 (variable) 17 -31.175 0.61 1.64769 33.8 18 89.899 1.20 1.95906 17.5 19 -116.225 2.00 20 (Aperture) ∞ 2.00 21 51.054 3.18 1.43700 95.1 22 -61.645 2.76 23 44.579 1.05 1.78880 28.4 24 18.854 0.36 25 19.721 2.74 1.45650 90.3 26 -59.805 (variable) 27 -20.055 0.73 1.64769 33.8 28 52.490 2.16 2.05090 26.9 29 -82.458 (variable) 30 30.744 5.44 1.55397 71.8 31 -124.044 7.60 32 ∞ 1.20 1.51633 64.1 33∞1.00 Image plane ∞ Various data Zoom ratio 2.00 Wide-angle Mid-range Telephoto Focal length 11.44 15.77 22.88 F-number 2.88 3.39 4.12 Half angle of view 57.50 40.30 27.40 Image height 10.75 10.75 10.75 Lens length 126.32 126.32 126.32 BF 9.39 9.39 9.39 d 9 21.48 12.13 2.78 d16 9.30 8.24 2.39 d26 9.57 12.76 24.44 d29 5.50 12.72 16.25 Zoom lens group data Group starting plane focal length 1 1 -16.02 2 10 32.25 3 17 67.96 4 27 -88.92 5 30 45.04 Table 1 shows the relationship between the above-mentioned conditional expressions and the respective numerical examples.
[0061] [Table 1]
[0062] Next, with reference to FIG. 11, an imaging device (surveillance camera) using the zoom lens of each embodiment as an imaging optical system will be described. FIG. 11 is a configuration diagram of the imaging device of each embodiment. In FIG. 11, 16 is an imaging optical system configured with any of the zoom lenses of Embodiments 1 to 5. In FIG. 11(B), 15 is a dome cover (protective cover) that protects the imaging optical system 16. The dome cover 15 is molded with a thickness of about several millimeters from a plastic material such as polymethyl methacrylate (PMMA) or polycarbonate (PC). Therefore, when an imaging device is designed to be equipped with a dome cover, the influence of the dome cover 15 (focal length and material) can be taken into consideration in the design, and various aberrations can be corrected.
[0063] In Figures 11(A) and 11(B), 11a and 11b denote surveillance camera bodies. Figure 11(B) shows an example in which surveillance camera body 11b is fitted with a dome cover 15 and attached to a ceiling. Surveillance camera body 11b is installed on the ceiling with dome cover 15 facing downward. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into surveillance camera bodies 11a and 11b and receives an image (subject image) formed by imaging optical system 16. Reference numeral 13 denotes a memory that records information corresponding to the subject image photoelectrically converted by imaging element 12. Reference numeral 14 denotes a network cable for transferring the subject image photoelectrically converted by imaging element 12. Note that the zoom lenses of the respective embodiments are not limited to surveillance cameras and can also be used in other imaging devices such as video cameras and digital cameras.
[0064] Furthermore, the imaging device of each embodiment may include a circuit for electrically correcting either or both of distortion and lateral chromatic aberration, along with the zoom lens of any of Embodiments 1 to 5. A configuration that can tolerate distortion and other aberrations of the zoom lens allows the number of lenses in the entire zoom lens to be reduced, facilitating miniaturization. Furthermore, electrically correcting lateral chromatic aberration reduces color bleeding in captured images, facilitating improved resolution.
[0065] According to each embodiment, for example, it is possible to provide a compact, high-magnification, high-image-quality, wide-angle zoom lens and an imaging device.
[0066] The disclosure of each embodiment includes the following configuration. (Configuration 1) A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises, in order from the object side to the image side, a third lens group having negative refractive power and a fourth lens group having positive refractive power; the rear lens group consists, in order from the object side to the image side, of a fifth lens group having negative refractive power and a sixth lens group having positive refractive power, or of the fifth lens group having negative refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and νm be the maximum Abbe number of the negative lenses in the fourth lens group referenced to the d-line. The sign of the amount of movement is positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, 0.60 <m2 / m3<2.10 28.0<νm A zoom lens characterized by satisfying the following conditional expressions: (Configuration 2) A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises a third lens group having positive refractive power, the rear lens group comprises, in order from the object side to the image side, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and νm be the maximum Abbe number of the negative lenses in the third lens group referenced to the d-line. The sign of the amount of movement is positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, 0.60 <m2 / m3<2.10 28.0<νm A zoom lens characterized by satisfying the following conditional expressions: (Configuration 3) 3. The zoom lens according to configuration 1 or 2, wherein the first lens group has three or more lenses. (Configuration 4) When the focal length of the lens group having negative refractive power included in the rear lens group is fr and the focal length of the first lens group is f1, 1.50 <fr / f1<6.00 4. The zoom lens according to any one of the configurations 1 to 3, wherein the following condition is satisfied: (Configuration 5) When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, -0.90 <f1 / f2<-0.45 5. The zoom lens according to any one of the first to fourth aspects, wherein the following condition is satisfied: (Configuration 6) When the zoom ratio is z, 1.80 <z<5.00 6. A zoom lens according to any one of configurations 1 to 5, wherein the following condition is satisfied: (Configuration 7) When the smallest Abbe number of the positive lenses in the second lens group based on the d-line is ν2, 25.0<ν2<53.0 7. The zoom lens according to any one of configurations 1 to 6, wherein the following condition is satisfied: (Configuration 8) 8. A zoom lens according to any one of configurations 1 to 7, wherein the second lens group has three or more lenses. (Configuration 9) When the total optical length of the zoom lens is L and the focal length of the zoom lens at the telephoto end is ft, 2.00 <L / ft<6.00 9. A zoom lens according to any one of configurations 1 to 8, wherein the following condition is satisfied: (Configuration 10) When the total optical length of the zoom lens is L, -7.50 <L / m2<-3.00 10. The zoom lens according to any one of configurations 1 to 9, wherein the following condition is satisfied: (Configuration 11) When the focal length of the zoom lens at the wide-angle end is fw, -2.50 <f1 / fw<-1.30 11. The zoom lens according to any one of configurations 1 to 10, wherein the following condition is satisfied: (Configuration 12) When the distance on the optical axis between the first lens group and the second lens group at the telephoto end is D1t and the distance on the optical axis between the first lens group and the second lens group at the wide-angle end is D1w, 0.00 <D1t / D1w<0.40 12. A zoom lens according to any one of configurations 1 to 11, characterized in that the following conditional expression is satisfied: (Configuration 13) A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises, in order from the object side to the image side, a third lens group having negative refractive power and a fourth lens group having positive refractive power; the rear lens group consists, in order from the object side to the image side, of a fifth lens group having negative refractive power and a sixth lens group having positive refractive power, or of the fifth lens group having negative refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and the sign of the amount of movement be positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, then: 0.60 <m2 / m3<2.10 A zoom lens characterized by satisfying the following conditional expressions: (Configuration 14) A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises a third lens group having positive refractive power, the rear lens group comprises, in order from the object side to the image side, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and the sign of the amount of movement be positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, then: 0.60 <m2 / m3<2.10 A zoom lens characterized by satisfying the following conditional expressions: (Configuration 15) 15. An imaging device comprising the zoom lens according to any one of configurations 1 to 14, and an imaging element that receives an image formed by the zoom lens.
[0067] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]
[0068] 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 comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises, in order from the object side to the image side, a third lens group having negative refractive power and a fourth lens group having positive refractive power; the rear lens group consists, in order from the object side to the image side, of a fifth lens group having negative refractive power and a sixth lens group having positive refractive power, or of the fifth lens group having negative refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and νm be the maximum Abbe number of the negative lenses in the fourth lens group based on the d-line. The sign of the amount of movement is positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, 0.60<m2 / m3<2.10 28.0<νm A zoom lens characterized by satisfying the following conditional expressions:
2. A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group is a third lens group having a positive refractive power, the rear lens group comprises, in order from the object side to the image side, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and νm be the maximum Abbe number of the negative lenses in the third lens group referenced to the d-line. The sign of the amount of movement is positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, 0.60<m2 / m3<2.10 28.0<νm A zoom lens characterized by satisfying the following conditional expressions:
3. 3. The zoom lens according to claim 1, wherein the first lens group includes three or more lenses.
4. When the focal length of the lens group having negative refractive power included in the rear lens group is fr and the focal length of the first lens group is f1, 1.50<fr / f1<6.00 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
5. When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, -0.90<f1 / f2<-0.45 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
6. When the zoom ratio is z, 1.80<z<5.00 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
7. When the smallest Abbe number of the positive lenses in the second lens group based on the d-line is ν2, 25.0<ν2<53.0 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
8. 3. The zoom lens according to claim 1, wherein the second lens group includes three or more lenses.
9. When the total optical length of the zoom lens is L and the focal length of the zoom lens at the telephoto end is ft, 2.00<L / ft<6.00 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
10. When the total optical length of the zoom lens is L, -7.50<L / m2<-3.00 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
11. When the focal length of the zoom lens at the wide-angle end is fw, -2.50<f1 / fw<-1.30 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
12. When the distance on the optical axis between the first lens group and the second lens group at the telephoto end is D1t and the distance on the optical axis between the first lens group and the second lens group at the wide-angle end is D1w, 0.00<D1t / D1w<0.40 3. The zoom lens according to claim 1, wherein the following condition is satisfied:
13. A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group comprises, in order from the object side to the image side, a third lens group having negative refractive power and a fourth lens group having positive refractive power; the rear lens group consists, in order from the object side to the image side, of a fifth lens group having negative refractive power and a sixth lens group having positive refractive power, or of the fifth lens group having negative refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and the sign of the amount of movement be positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, and 0.60<m2 / m3<2.10 A zoom lens characterized by satisfying the following conditional expressions:
14. A zoom lens comprising, 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, an intermediate lens group, and a rear lens group, the intermediate lens group is a third lens group having a positive refractive power, the rear lens group comprises, in order from the object side to the image side, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power; During zooming from the wide-angle end to the telephoto end, the first lens group remains stationary, and the spacing between adjacent lens groups changes. the intermediate lens group has five or more lenses, Let m2 be the amount of movement of the second lens group from the wide-angle end to the telephoto end, m3 be the amount of movement of the third lens group from the wide-angle end to the telephoto end, and the sign of the amount of movement be positive when the lens group is located closer to the image at the telephoto end than at the wide-angle end, and 0.60<m2 / m3<2.10 A zoom lens characterized by satisfying the following conditional expressions:
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.