Zoom lens and image capturing device

Abstract

To provide a high-performance zoom lens which offers a large aperture ratio, and yet is compact as a whole and well corrected for aberrations, and an image capturing device.SOLUTION: A zoom lens provided herein comprises a front group having negative refractive power as a whole and a rear group having positive refractive power as a whole, is configured such that five or less lens groups move to change distances therebetween when zooming from the wide-angle end to the telephoto end, and has specific optical characteristics represented by specific expressions.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a zoom lens and an image pickup apparatus. [Background technology]

[0002] Imaging devices using solid-state imaging elements, such as digital still cameras and digital video cameras, are widely used. Examples of such imaging devices include digital still cameras, digital video cameras, broadcast cameras, security cameras, and vehicle-mounted cameras. In any imaging device, there is a strong market demand for zoom lenses that have a large aperture ratio, a small optical system, and high optical performance.

[0003] As an optical configuration of a zoom lens, for example, a positive lead type configuration is known, which has a lens group with positive refractive power closest to the object. In a positive lead type zoom lens, a strong negative refractive power is generally placed in the second lens group, which is the second from the object side, and a large magnification change load is placed on the second lens group, making it easy to realize a high magnification change. In such a positive lead type zoom lens, the tendency for telephoto is strong, so the total optical length can be shortened compared to the focal length.

[0004] Known zoom lenses include those having lens groups with, in order from the object side, positive, negative, positive, negative, positive refractive powers, with the fourth lens group serving as a focus group (see, for example, Patent Document 1).Also known zoom lenses include those having lens groups with, in order from the object side, positive, negative, positive, negative, positive refractive powers, with the second lens group serving as a focus group (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 092295 [Patent Document 2] JP 2019-138941 A Summary of the Invention [Problem to be solved by the invention]

[0006] Here, in order to obtain a zoom lens with a small F-number and high optical performance, it is necessary to satisfactorily correct various aberrations that occur due to a large aperture ratio. Therefore, in a zoom lens with a small F-number, it is difficult to arrange a strong refractive power in each lens group compared to a zoom lens with a large F-number, and the optical system is likely to become large. In addition, in order to obtain a zoom lens with a small F-number, it is preferable to arrange a lens group with a strong positive refractive power on the image surface side, that is, at the rear of the optical system. However, if a lens group with a strong positive refractive power is arranged at the rear of the optical system, it becomes difficult to obtain a zoom lens with a strong telephoto tendency, and it becomes difficult to shorten the total optical length. Thus, in order to realize a zoom lens that has a large aperture ratio, high optical performance, and is compact, it is necessary to appropriately set the power arrangement of each lens group, the imaging magnification, the lens configuration, the distance that each lens group moves with the magnification change, etc.

[0007] In the zoom lens described in Patent Document 1, the back focus is long, and the optical system cannot be made compact.

[0008] In the zoom lens described in Patent Document 2, the second lens group is not suitable for rapid focusing because it has a large number of lenses and is heavy. In addition, because the second lens group is heavy, the drive mechanism for moving the second lens group during focusing becomes large. This leads to a problem of an increase in the diameter of the lens barrel.

[0009] An object of one aspect of the present invention is to provide a high-performance zoom lens and imaging apparatus that has a large aperture ratio, is small overall, and has excellent correction of various aberrations. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, a zoom lens according to one aspect of the present invention is a zoom lens having a plurality of lens groups, When the lens group arranged closer to the object side than the widest air gap between the lens groups at the wide-angle end is defined as the front group, and the lens group arranged closer to the image plane side than the air gap is defined as the rear group, the front group is composed of, in order from the object side, a lens group P having positive refractive power, and an intermediate group M1 including one or more lens groups and having negative refractive power as a whole, and has negative refractive power as a whole; the rear group is composed of, in order from the object side, a middle group M2 including one or more lens groups and having positive refractive power as a whole, a lens group F having negative refractive power as a whole, and a rear group R including one or more lens groups and having positive refractive power as a whole; When zooming from the wide-angle end to the telephoto end, The spacing between adjacent lens groups changes, The number of lens groups that move to change the spacing between adjacent lens groups is five or less, The lens group P moves toward the object side, At least one lens group having a negative refractive power among the lens groups included in the intermediate group M1 moves gradually toward the image surface side, and At least one lens group having a positive refractive power among the lens groups included in the intermediate group M2 moves along a locus that is convex toward the image surface side, During focusing, the lens group F moves along the optical axis of the zoom lens, The following formula is satisfied: 0.5≦bfw / Yw≦1.4 (1) 0.5≦fp / ft≦1.5 (2) -0.9≦fm1 / fw≦-0.15 (3) however, bfw: back focus of the optical system of the zoom lens at the wide-angle end Yw: Maximum image height at the wide-angle end fp: focal length of the lens group P ft: focal length of the optical system of the zoom lens at the telephoto end fm1: composite focal length of the intermediate group M1 at the wide-angle end fw: focal length of the optical system of the zoom lens at the wide-angle end

[0011] In order to solve the above-mentioned problem, an imaging device according to one aspect of the present invention includes the zoom lens and an imaging element on the image plane side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal. Effect of the Invention

[0012] According to one aspect of the present invention, it is possible to provide a high-performance zoom lens and an imaging device that are small overall and in which various aberrations are well corrected. [Brief description of the drawings]

[0013] [Figure 1] 1 is a lens sectional view illustrating a schematic optical configuration of a zoom lens at a wide-angle end according to a first embodiment. [Diagram 2] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 1 when focused on an object at infinity in the wide-angle end state. [Diagram 3] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration when the zoom lens of Example 1 is in an intermediate focal length state and focused on an object at infinity. [Figure 4] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 1 when focused on an object at infinity in the telephoto end state. [Diagram 5] FIG. 11 is a lens sectional view illustrating an optical configuration of a zoom lens at a wide-angle end according to a second embodiment. [Figure 6] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 2 when focused on an object at infinity in the wide-angle end state. [Figure 7] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 2 when focused on infinity in an intermediate focal length state. [Figure 8] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 2 when focused on an object at infinity in the telephoto end state. [Figure 9] FIG. 11 is a lens sectional view illustrating an optical configuration of a zoom lens at a wide-angle end according to a third embodiment. [Figure 10] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on an object at infinity in the wide-angle end state. [Figure 11] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 3 when focused on an object at infinity in an intermediate focal length state. [Figure 12] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 3 when focused on an object at infinity in the telephoto end state. [Figure 13] FIG. 11 is a lens sectional view illustrating an optical configuration of a zoom lens at a wide-angle end according to a fourth embodiment. [Figure 14] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity in the wide-angle end state. [Figure 15] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity in an intermediate focal length state. [Figure 16] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity in the telephoto end state. [Figure 17] 1 is a diagram illustrating an example of a configuration of an imaging device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of a zoom lens and an imaging device according to the present invention will be described. More specifically, this embodiment relates to a zoom lens and an imaging device suitable for an imaging device using a solid-state imaging element (CCD, CMOS, etc.) such as a digital still camera or a digital video camera. However, the zoom lens and imaging device described below are one aspect of the zoom lens and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following aspects.

[0015] 1. Zoom Lens 1-1.Optical configuration The optical configuration of a zoom lens according to one embodiment of the present invention will be described. The zoom lens according to this embodiment is a zoom lens having a plurality of lens groups, and is composed of a front group which is a set of two or more lens groups arranged closer to the object side than the widest air space between the lens groups at the wide-angle end, and a rear group which is a set of three or more lens groups arranged closer to the image plane side than the air space. The zoom lens does not include any lens groups other than the lens groups included in the front group or the rear group, but may include an optical element that does not have substantial refractive power.

[0016] In this specification, the term "lens group" refers to a collection of one or more lenses that work together during a magnification change operation. The lenses in a lens group move while maintaining their relative positional relationship during a magnification change operation. The magnification change operation is performed by changing the spacing between the lens groups, and the spacing between lenses belonging to the same lens group does not change during the magnification change operation.

[0017] In this specification, "the widest air spacing between the lens groups at the wide-angle end" refers to the spacing between adjacent lens groups, from the vertex of the image-side lens surface of the lens closest to the image side in one lens group to the vertex of the object-side lens surface of the lens closest to the object side in the other lens group.

[0018] The optical configuration of the zoom lens will be further explained below.

[0019] (1) Front group The front group has negative refractive power as a whole and is composed of, in order from the object side, a lens group P and an intermediate group M1.

[0020] The lens group P is disposed closest to the object. The lens group P has a positive refractive power as a whole, and the specific lens configuration is not particularly limited. The lens group P may be configured to include, for example, two lenses having a positive refractive power. This configuration is preferable from the viewpoint of strengthening the positive refractive power of the lens group P. This configuration is also preferable from the viewpoint of miniaturizing the optical system of the zoom lens, since it can strengthen the telephoto tendency at the telephoto end while achieving a high zoom ratio. Note that a strong telephoto tendency means that the telephoto ratio has a smaller value.

[0021] In this specification, the term "optical system of a zoom lens" refers to an optical system including optical elements from the lens closest to the object to the lens closest to the image surface. The optical system of a zoom lens may further include optical elements outside the above range, and may or may not include an optical element that blocks light of a specific wavelength, such as a cover glass of an image sensor or an infrared cut filter. In addition, in this specification, the distance from the object-side lens surface of the lens closest to the object on the optical axis of the optical system of a zoom lens to the image surface is referred to as the "total optical length."

[0022] It is preferable that the lens group P includes at least one lens having negative refractive power. This configuration is preferable from the viewpoint of realizing a zoom lens having excellent optical performance, since it makes it easier to correct spherical aberration, chromatic aberration, and the like.

[0023] The intermediate group M1 is disposed in the front group on the image surface side of the lens group P. The intermediate group M1 may be one lens group or a collection of two or more lens groups. The intermediate group M1 includes one or more lens groups and has negative refractive power as a whole.

[0024] Among the lens groups having negative refractive power included in the intermediate group M1, the lens group having the largest negative refractive power is referred to as lens group N. The specific lens configuration of lens group N is not particularly limited.

[0025] The intermediate group M1 is not particularly limited in other configurations as long as it has a negative refractive power as a whole. For example, the intermediate group M1 may have one or more lens groups having positive or negative refractive power in addition to the lens group N. This configuration is preferable from the viewpoint of realizing a zoom lens having excellent optical performance, since it is easy to correct the curvature of field and spherical aberration caused by magnification change. In addition, it is preferable that the intermediate group M1 has a convex lens closest to the object side. This configuration is preferable from the viewpoint of realizing a zoom lens with a small barrel diameter, since it is possible to lower the ray height of the outermost ray of the axial light beam incident on the intermediate group M2 and the aperture stop described later.

[0026] The front group may be substantially composed of only the lens group P and the intermediate group M1. In the case where the front group further includes a lens group other than those mentioned above, that lens group is included in the intermediate group M1.

[0027] (2) Rear group The rear group has positive refractive power as a whole and is composed of, from the object side, an intermediate group M2, a lens group F, and a rear group R.

[0028] The intermediate group M2 is disposed closest to the object in the rear group. The intermediate group M2 may be one lens group or a collection of two or more lens groups. The intermediate group M2 is composed of one or more lens groups and has positive refractive power as a whole. The lens configuration or lens group configuration of the intermediate group M2 may be appropriately determined within a range in which the intermediate group M2 has positive refractive power as a whole.

[0029] It is preferable that the intermediate group M2 has a convex lens closest to the object side. This configuration is preferable from the viewpoint of realizing a compact zoom lens, since it is easy to shorten the total optical length. This configuration is also preferable from the viewpoint of miniaturizing the focus unit, since it is easy to lower the height of the outermost rays of the axial light beam and the peripheral light beam incident on the lens group F.

[0030] It is preferable that the image-side lens surface of the lens closest to the image side in the intermediate group M2 be convex toward the image side. This configuration is preferable from the viewpoint of realizing a bright zoom lens with a small F-number.

[0031] From the viewpoint of miniaturization of the vibration-proof drive mechanism, it is preferable that the intermediate group M2 has a vibration-proof group V with negative refractive power that moves in a direction perpendicular to the optical axis. The vibration-proof group V may be composed of a plurality of lenses, but it is preferable that the vibration-proof group V is composed of one single lens or one cemented lens. This configuration is preferable from the viewpoint of miniaturization and weight reduction of the vibration-proof group V.

[0032] When the intermediate group M2 has the vibration isolation group V, it may include one or more lenses on the object side of the vibration isolation group V and on the image side of the vibration isolation group V. In this case, it is preferable that the one or more lenses arranged on the object side of the vibration isolation group V in the intermediate group M2 have positive refractive power as a whole, and that the one or more lenses arranged on the image side of the vibration isolation group V in the intermediate group M2 have positive refractive power as a whole. This configuration is preferable from the viewpoint of making the vibration isolation group compact.

[0033] The lens group F is a lens group in the rear group that is disposed on the image surface side of the middle group M2. The lens group F has negative refractive power as a whole.

[0034] The lens group F has a negative refractive power as a whole, and the specific lens configuration is not particularly limited. More preferably, it has at least one lens having a positive refractive power and at least one lens having a negative refractive power. This configuration is preferable from the viewpoint of obtaining a high-performance zoom lens in which various aberrations such as spherical aberration and chromatic aberration are well corrected over the entire object distance.

[0035] It is particularly preferable that the lens group F be composed only of a cemented lens formed by cementing together one lens having positive refractive power and one lens having negative refractive power, from the viewpoint of realizing high-speed autofocusing by reducing the weight of the focus group.

[0036] Lens group F is disposed closer to the image plane than intermediate group M2, and is disposed relatively farther back in the optical system of the zoom lens. This configuration is preferable from the viewpoints of reducing the lens diameter of lens group F and reducing the weight of lens group F, because a light beam converged by intermediate group M2 from the object side is incident on lens group F.

[0037] The rear group R is disposed closer to the image plane side than the lens group F in the rear group. The rear group R has at least one lens group, and more specifically, may be one lens group or a collection of two or more lens groups. The total refractive power of the rear group R is not particularly limited. For example, the rear group R may be configured to have a positive refractive power as a whole. This configuration is preferable from the viewpoint of reducing the F-number of the optical system of the zoom lens. On the other hand, the rear group R may be configured to have a negative refractive power as a whole. This configuration is preferable from the viewpoint of shortening the total optical length at the telephoto end, since it becomes easier to obtain a zoom lens with a stronger telephoto tendency at the telephoto end.

[0038] The rear group R may include two or more lens groups as long as the effects of this embodiment can be obtained. From the viewpoint of shortening the total optical length, the rear group R may be one lens group. From the viewpoint of effectively correcting field curvature over the entire zoom range, the rear group R may include two or more lens groups.

[0039] (3) Aperture diaphragm The zoom lens may include an aperture stop. The aperture stop may be disposed adjacent to the intermediate group M2 on the object side of the intermediate group M2, or may be disposed inside the intermediate group M2. A configuration in which the aperture stop is disposed adjacent to the object side of the intermediate group M2 allows the entrance pupil position to be disposed closer to the object side than a configuration in which the aperture stop is disposed inside the intermediate group M2. This is preferable in that it is easy to reduce the diameter of the peripheral light beam passing through the lens group P at the telephoto end, and it is easy to reduce the diameter of the front lens. The front lens is the lens disposed closest to the object side among the lenses included in the optical system of the zoom lens.

[0040] The aperture stop may be disposed inside the intermediate group M2. This configuration is preferable from the viewpoint of making the aperture mechanism compact, since the aperture diameter can be made small by the convergence action of the positive refractive power of the intermediate group M2.

[0041] 1-2.Operation (1)Zooming A zoom lens changes magnification by changing the air space on the optical axis between adjacent lens groups when zooming from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end. In particular, when zooming from the wide-angle end to the telephoto end, the air space between the front and rear groups, i.e., the air space between the middle group M1 and the middle group M2, is changed so as to decrease.

[0042] During zooming, the number of lens groups that move to change the spacing between adjacent lens groups is 5 or less. Keeping the number of lens groups that move during zooming within this range is preferable from the perspective of reducing the diameter of the lens barrel, since it allows the mechanism for moving the lens groups to be simplified.

[0043] When zooming from the wide-angle end to the telephoto end, the lens group P moves toward the object side. This movement is preferable from the viewpoint of realizing a compact zoom lens with a short overall optical length at the wide-angle end. Note that the movement of the lens group P during zooming is not particularly limited. For example, when zooming from the wide-angle end to the telephoto end, the lens group P may move gradually toward the object side. In this specification, "moving gradually" refers to a state in which the lens group moves in one direction. Gradual movement is also referred to as monotonic movement in this technical field.

[0044] During zooming from the wide-angle end to the telephoto end, at least one lens group having negative refractive power among the lens groups included in the middle group M1 moves gradually toward the image plane. This operation is preferable from the viewpoint of realizing a zoom lens with a small lens barrel diameter, since it is possible to lower the height of the outermost ray of the axial light beam incident on the middle group M2 and the aperture stop. This operation is also preferable from the viewpoint of shortening the overall optical length at the telephoto end, since it is easy to reduce the telephoto ratio.

[0045] During zooming from the wide-angle end to the telephoto end, at least one lens group having positive refractive power among the lens groups included in the middle group M2 moves along a locus that is convex toward the image surface side. That is, during zooming from the wide-angle end to the telephoto end, the lens group moves toward the image surface side and then toward the object side. Also, during zooming from the telephoto end to the wide-angle end, the lens group moves toward the image surface side and then further toward the object side. This operation is preferable from the viewpoint of obtaining a zoom lens with high optical performance, since it is easy to satisfactorily correct the curvature of field in the entire zoom range.

[0046] During zooming from the wide-angle end to the telephoto end, it is preferable for the lens group F to move along a locus that is convex toward the image surface. This operation is preferable because it can suppress fluctuations in the focal plane that accompany zooming, and it also makes it easy to effectively correct curvature of field over the entire zoom range.

[0047] It is preferable that the rear group R does not move during zooming. In a zoom lens, by making the rear group R, which is disposed closest to the image plane, a fixed group, it becomes easy to make the image plane side of the lens barrel have a sealed structure or the like, which is preferable from the viewpoint of dustproof and waterproof structures. Furthermore, by making the rear group R a fixed group, a cam structure for moving the rear group R is not necessary, and a simple lens barrel structure can be achieved, which is preferable from the viewpoint of miniaturizing the lens barrel and improving manufacturability.

[0048] (2) Focusing When the zoom lens focuses, the lens group F moves along the optical axis of the zoom lens. By using the lens group F as the focus group, high-speed autofocus can be achieved, which is preferable from the viewpoint of reducing the load on the focus drive system. In addition, by using the lens group F as the focus group, the fluctuation of the angle of view accompanying the movement of the focus group can be suppressed. Therefore, not only when the contrast AF method is adopted, but also when the image plane phase difference AF method is adopted, a zoom lens suitable for video shooting using a tracking AF function can be obtained. Note that, since the lateral magnification of the lens group F is a value greater than 1, the lens group F moves toward the image plane side when focusing from infinity to a close object.

[0049] When focusing the zoom lens, in addition to the lens group F, a lens group other than the lens group F or a part of the lens group may move. For example, a so-called floating focus method may be adopted. This configuration is preferable from the viewpoint of obtaining a high-performance zoom lens, since it facilitates aberration correction for close-distance objects. On the other hand, from the viewpoint of reducing the size and weight of the lens barrel, it is particularly preferable that only the lens group F moves in the zoom lens when focusing.

[0050] 1-3.Formula It is desirable for the zoom lens to employ the above-mentioned configuration and to satisfy at least one of the following expressions.

[0051] 1-3-1.Formula (1) 0.5≦bfw / Yw≦1.4 (1) however, bfw: Back focus of the optical system of a zoom lens at the wide-angle end Yw: Maximum image height at the wide-angle end

[0052] Equation (1) is an equation for appropriately defining the ratio between the back focus of the optical system of the zoom lens at the wide-angle end and the maximum image height of the zoom lens at the wide-angle end. Here, if the optical system of the zoom lens includes a cover glass, the back focus bfw is calculated with the cover glass thickness as the air equivalent distance. Satisfying equation (1) is preferable from the viewpoint of miniaturizing the overall length, since the back focus of the zoom lens at the wide-angle end is shortened.

[0053] When bfw / Yw is below the lower limit in formula (1), the back focus of the zoom lens at the wide-angle end becomes too short, and the inclination angle of the incident angle to the imaging surface with respect to the optical axis becomes too large. Here, a condenser lens such as an on-chip microlens for efficiently receiving the incident angle is provided for each pixel on the imaging surface of the image sensor, and the light receiving angle of the on-chip microlens is limited within a predetermined range. Therefore, if the exit angle from the zoom lens becomes too large, there is a problem that the peripheral light reduction (shading) due to the mismatch with the on-chip microlens becomes large. On the other hand, when bfw / Yw exceeds the upper limit in formula (1), the back focus of the zoom lens at the wide-angle end becomes too long, and it may be difficult to reduce the overall length of the zoom lens.

[0054] From the viewpoint of reducing the overall length, bfw / Yw is preferably 0.55 or more, more preferably 0.60 or more, even more preferably 0.65 or more, and even more preferably 0.70 or more. Also, from the viewpoint of reducing the overall length of the zoom lens, bfw / Yw is preferably 1.35 or less, more preferably 1.3 or less, and even more preferably 1.25 or less.

[0055] 1-3-2.Formula (2) 0.5≦fp / ft≦1.5 (2) fp: focal length of lens group P ft: focal length of the zoom lens optical system at the telephoto end

[0056] Equation (2) is an equation for appropriately defining the ratio between the focal length of the optical system of the zoom lens at the telephoto end and the focal length of the lens group P. Satisfying equation (2) is preferable from the viewpoint of realizing a compact zoom lens with a small telephoto ratio, since the focal length of the lens group P falls within an appropriate range with respect to the focal length of the optical system of the zoom lens at the telephoto end. Furthermore, satisfying equation (2) is preferable from the viewpoint of realizing a zoom lens with high optical performance, since the focal length of the lens group P falls within an appropriate range, allowing for better correction of spherical aberration and axial chromatic aberration.

[0057] When fp / ft falls below the lower limit in formula (2), the refractive power of the lens group P may become too strong for the focal length of the optical system of the zoom lens at the telephoto end. In this case, it may be difficult to satisfactorily correct spherical aberration and axial chromatic aberration, and it may be difficult to realize a zoom lens with high optical performance. On the other hand, when fp / ft exceeds the upper limit in formula (2), the refractive power of the lens group P may become too weak for the focal length of the optical system of the zoom lens at the telephoto end. In this case, the total optical length at the telephoto end becomes long, and it may be difficult to realize a compact zoom lens with a small telephoto ratio.

[0058] From the viewpoint of satisfactorily correcting spherical aberration and axial chromatic aberration, fp / ft is preferably 1.3 or less, more preferably 1.2 or less, even more preferably 1.1 or less, and even more preferably 1.0 or less. Also, from the viewpoint of realizing a compact zoom lens with a small telephoto ratio, fp / ft is preferably 0.55 or more, more preferably 0.60 or more, even more preferably 0.65 or more, and even more preferably 0.70 or more.

[0059] 1-3-3.Formula (3) -0.9≦fm1 / fw≦-0.15 (3) fm1: composite focal length of the intermediate group M1 at the wide-angle end fw: focal length of the optical system of the zoom lens at the wide-angle end

[0060] Equation (3) is an equation for appropriately defining the ratio between the focal length of the optical system of the zoom lens at the wide-angle end and the composite focal length of the middle group M1 at the wide-angle end. By satisfying equation (3), the composite focal length of the middle group M1 at the wide-angle end falls within an appropriate range relative to the focal length of the optical system of the zoom lens at the wide-angle end, making it possible to more effectively correct the curvature of field that is likely to occur at the wide-angle end. This is therefore preferable from the viewpoint of realizing a zoom lens with high optical performance over the entire zoom range. In this specification, the "composite focal length" of a lens group refers to the focal length of the entire lens group including one or more lenses.

[0061] When fm1 / fw is below the lower limit in formula (3), the refractive power of the entire intermediate group M1 at the wide-angle end becomes small relative to the focal length of the optical system of the zoom lens at the wide-angle end. In this case, it becomes difficult to reduce the telephoto ratio, which may make it difficult to obtain a compact zoom lens with a short overall optical length. On the other hand, when fm1 / fw is above the upper limit in formula (3), the refractive power of the entire intermediate group M1 at the wide-angle end becomes large relative to the focal length of the optical system of the zoom lens at the wide-angle end. In this case, curvature of field is likely to occur at the wide-angle end, which may make it difficult to realize a zoom lens with high optical performance over the entire zoom range.

[0062] From the viewpoint of achieving a zoom lens with high optical performance by satisfactorily correcting the curvature of field, fm1 / fw is preferably -0.20 or less, more preferably -0.25 or less, even more preferably -0.30 or less, and even more preferably -0.35 or less. Also, from the viewpoint of achieving a compact zoom lens with a short overall optical length, fm1 / fw is preferably -0.85 or more, more preferably -0.80 or more, even more preferably -0.75 or more, and even more preferably -0.70 or more.

[0063] 1-3-4.Formula (4) 0.05≦Dm / Tw≦0.20 (4) Dm: the distance on the optical axis between the intermediate group M1 and the intermediate group M2 at the wide-angle end Tw: Total optical length at the wide-angle end

[0064] Equation (4) is an equation for appropriately defining the ratio between the total optical length at the wide-angle end and the distance on the optical axis between the middle group M1 and the middle group M2 at the wide-angle end. Here, when the optical system of the zoom lens includes a cover glass, the total optical length Tw is calculated as the air-equivalent distance for the thickness of the cover glass. Satisfying equation (4) is preferable from the viewpoint of realizing a zoom lens with a short total length at the wide-angle end, because the distance on the optical axis between the middle group M1 and the middle group M2 at the wide-angle end falls within an appropriate range with respect to the total optical length at the wide-angle end.

[0065] When Dm / Tw is below the lower limit in formula (4), the distance on the optical axis between the middle group M1 and the middle group M2 at the wide-angle end may become too short compared to the total optical length at the wide-angle end. In this case, it becomes difficult to ensure a sufficient amount of movement of the middle group M1 accompanying zooming, so it becomes necessary to increase the space in which the lens group P can move in order to ensure a desired zoom ratio. As a result, the total optical length at the telephoto end becomes long, so it may be difficult to obtain a small-sized zoom lens with a small telephoto ratio. When Dm / Tw exceeds the upper limit in formula (4), the distance on the optical axis between the middle group M1 and the middle group M2 at the wide-angle end becomes long compared to the total optical length at the wide-angle end, so it may be difficult to obtain a zoom lens with a short total length at the wide-angle end. In addition, when Dm / Tw exceeds the upper limit in formula (4), the ray height of the outermost ray of the axial light beam incident on the middle group M2 and the aperture stop tends to become large, so it may be difficult to reduce the lens barrel diameter.

[0066] From the viewpoint of compactness, Dm / Tw is preferably 0.195 or less, more preferably 0.19 or less, even more preferably 1.85 or less, and even more preferably 0.18 or less. Also, from the viewpoint of a compact zoom lens with a small telephoto ratio, Dm / Tw is preferably 0.06 or more, more preferably 0.07 or more, even more preferably 0.08 or more, and even more preferably 0.09 or more.

[0067] 1-3-5.Formula (5) 0.5≦|Xp| / |Xn|≦2.0···(5) Xp: the distance on the optical axis between the position of the lens group P at the wide-angle end and the position of the lens group P at the telephoto end Xn: the distance on the optical axis between the position of lens group N at the wide-angle end and the position of lens group N at the telephoto end

[0068] Equation (5) is an equation for appropriately defining the ratio between the distance on the optical axis between the position of lens group N at the wide-angle end and the position of lens group N at the telephoto end, and the distance on the optical axis between the position of lens group P at the wide-angle end and the position of lens group P at the telephoto end. In other words, equation (5) defines the relationship between the distances that lens group N and lens group P move from the wide-angle end to the telephoto end during zooming.

[0069] Satisfying expression (5) brings the ratio of the distance traveled by lens group P during zooming to the distance traveled by lens group N within an appropriate range, which is preferable from the standpoint of realizing a compact zoom lens with a short overall length at the telephoto end and a small lens barrel diameter.

[0070] When |Xp| / |Xn| is below the lower limit in formula (5), the distance that the lens group P moves during zooming may become too small relative to the distance that the lens group N moves during zooming. In this case, it is necessary to increase the distance that the lens group N moves in order to obtain a desired zoom ratio. In order to increase the distance that the lens group N moves, it is necessary to increase the air gap on the optical axis between the middle group M1 and the middle group M2 at the wide-angle end. As a result, the total optical length at the wide-angle end becomes long, and it may be difficult to obtain a zoom lens with a short total length. When |Xp| / |Xn| is above the upper limit in formula (5), the distance that the lens group P moves during zooming may become too large relative to the distance that the lens group N moves during zooming. In this case, it is difficult to shorten the total optical length at the telephoto end, and it may be difficult to obtain a small zoom lens with a small telephoto ratio.

[0071] From the viewpoint of obtaining a compact zoom lens with a small telephoto ratio, |Xp| / |Xn| is preferably 1.9 or less, more preferably 1.8 or less, even more preferably 1.7 or less, and even more preferably 1.5 or less. Also, from the viewpoint of obtaining a zoom lens with a short overall length, |Xp| / |Xn| is preferably 0.55 or more, more preferably 0.60 or more, even more preferably 0.65 or more, and even more preferably 0.70 or more.

[0072] 1-3-6.Formula (6) 1.5≦|{1-(βft) 2}×(βrt) 2 |≦9.5···(6) βft: Lateral magnification of lens group F at the telephoto end when focused on infinity βrt: The lateral magnification of the rear group R at the telephoto end when focused at infinity

[0073] Equation (6) represents the ratio of the distance the focal plane moves to the distance the lens group F moves, and is used to set within an appropriate range the position sensitivity of the lens group F. Satisfying equation (6) is preferable from the standpoint of optimizing the driving accuracy during focusing and the distance moved during focusing.

[0074] |{1-(βft) 2}×(βrt) 2 If | falls below the lower limit in formula (6), the distance that the lens group F moves during focusing increases, which may lead to an increase in the size of the focus actuator that drives it. In this case, it may be difficult to realize a compact zoom lens. |{1-(βft) 2}×(βrt) 2 If | exceeds the upper limit in the formula (6), the position sensitivity of the lens group F becomes too large, and the required driving accuracy for focusing becomes high, which may make it difficult to improve the focusing accuracy.

[0075] From the viewpoint of improving focusing accuracy, |{1-(βft) 2}×(βrt) 2 is preferably 9.0 or less, more preferably 8.5 or less, even more preferably 8.0 or less, and even more preferably 7.5 or less. From the viewpoint of miniaturization of the zoom lens, |{1-(βft) 2}×(βrt) 2 is preferably 1.7 or more, more preferably 1.9 or more, even more preferably 2.1 or more, and even more preferably 2.3 or more.

[0076] 1-3-7.Formula (7) 0.7≦fm2p / fm2≦2.0 (7) fm2p: The composite focal length of all the lenses in the intermediate group M2 located closer to the object than the image stabilization group V at the telephoto end fm2: The composite focal length of the intermediate group M2 at the telephoto end

[0077] Equation (7) is an equation for appropriately defining the ratio between the composite focal length of the intermediate group M2 at the telephoto end and the composite focal length at the telephoto end of all lenses in the intermediate group M2 arranged on the object side of the image stabilization group V. Satisfying equation (7) is preferable from the viewpoint of preventing an increase in size of the image stabilization drive mechanism, because the height of the outermost ray of the axial light beam entering the image stabilization group V becomes lower.

[0078] If fm2p / fm2 falls below the lower limit in formula (7), the refractive power of the entire lens, which is disposed on the object side of the intermediate group M2 relative to the vibration reduction group V in the intermediate group M2, at the telephoto end may become too strong relative to the composite focal length of the intermediate group M2 at the telephoto end. In this case, it may become difficult to satisfactorily correct spherical aberration and axial chromatic aberration. If fm2p / fm2 exceeds the upper limit in formula (7), it becomes difficult to lower the ray height of the outermost ray of the axial light beam incident on the vibration reduction group V, and the vibration reduction drive mechanism may become large.

[0079] From the viewpoint of miniaturization of the vibration-proof drive mechanism, fm2p / fm2 is preferably 1.9 or less, more preferably 1.8 or less, even more preferably 1.7 or less, and even more preferably 1.6 or less. Also, from the viewpoint of excellent correction of spherical aberration and axial chromatic aberration, fm2p / fm2 is preferably 0.8 or more, more preferably 0.9 or more, even more preferably 1.0 or more, and even more preferably 1.1 or more.

[0080] 1-3-8.Formula (8) -3.3≦fm2v / fm2≦-1.2 (8) fm2v: focal length of vibration-isolating group V

[0081] Equation (8) is an equation for appropriately defining the ratio between the composite focal length of the intermediate group M2 at the telephoto end and the focal length of the image stabilization group V. Satisfying equation (8) is preferable from the standpoint of suppressing aberrations that occur during image stabilization while controlling the drive width of the image stabilization group V during image stabilization within an appropriate range.

[0082] When fm2v / fm2 falls below the lower limit in formula (8), the drive width of the vibration reduction group V for blur correction becomes small, which is advantageous for miniaturizing the vibration reduction drive mechanism, but it may become difficult to correct spherical aberration and astigmatism during vibration reduction.On the other hand, when fm2v / fm2 exceeds the upper limit in formula (8), the drive width of the vibration reduction group V for blur correction becomes large, which may make it difficult to miniaturize the optical system of the zoom lens.

[0083] From the viewpoint of compactness of the zoom lens, fm2v / fm2 is preferably -1.3 or less, more preferably -1.4 or less, even more preferably -1.5 or less, and even more preferably -1.6 or less. Also, from the viewpoint of correction of spherical aberration and astigmatism during vibration reduction, fm2v / fm2 is preferably -3.2 or more, more preferably -3.0 or more, even more preferably -2.9 or more, and even more preferably -2.8 or more.

[0084] 2. Imaging device Next, an image pickup device according to an embodiment of the present invention will be described. The image pickup device includes the zoom lens according to the embodiment described above and an image sensor provided on the image plane side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

[0085] Here, the imaging element is not limited, and a solid-state imaging element such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used as the imaging element, and a silver halide film, an infrared cut filter (IRCF), etc. can also be used. The imaging device according to this embodiment is suitable for imaging devices using the above-mentioned solid-state imaging element, such as digital cameras and video cameras. In addition, the imaging device may be a lens-fixed imaging device in which a lens is fixed to a housing, or a lens-interchangeable imaging device such as a single-lens reflex camera and a mirrorless single-lens camera. In particular, the zoom lens according to this embodiment can ensure a back focus suitable for an interchangeable lens system. Therefore, it is suitable for imaging devices such as a single-lens reflex camera equipped with an optical finder, a phase difference sensor, and a reflex mirror for branching light to these.

[0086] Fig. 17 is a diagram showing a schematic example of the configuration of an imaging device according to this embodiment. As shown in Fig. 17, a mirrorless single-lens camera 1 has a body 2 and a lens barrel 3 that is detachable from the body 2. The mirrorless single-lens camera 1 is one form of an imaging device.

[0087] The lens barrel 3 has a zoom lens 30. The zoom lens 30 includes a first lens group 31, a second lens group 32, a third lens group 33, a fourth lens group 34, and a fifth lens group 35. The zoom lens 30 is configured to satisfy, for example, the above-mentioned expressions (1) to (3). An aperture stop S is disposed on the object side of the third lens group 33.

[0088] The first lens group 31 has a positive refractive power as a whole and corresponds to the lens group P described above. The second lens group 32 has a negative refractive power as a whole and corresponds to the middle group M1 described above. The third lens group 33 has a positive refractive power as a whole and corresponds to the middle group M2 described above. The fourth lens group 34 has a negative refractive power as a whole and corresponds to the lens group F described above. The fifth lens group 35 has a negative refractive power as a whole and corresponds to the rear group R described above.

[0089] The main body 2 has a CCD sensor 21 as an imaging element and a cover glass 22. The CCD sensor 21 is disposed in the main body 2 at a position where the central axis is the optical axis OA of the zoom lens 30 in the lens barrel 3 attached to the main body 2. Instead of the cover glass 22, the main body 2 may have a parallel plane plate having no substantial refractive power, such as an infrared cut filter (IRCF).

[0090] Since the mirrorless single-lens camera 1 includes the zoom lens 30, it is possible to capture high-quality images in which various aberrations are well corrected, while still being compact overall.

[0091] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention.

[0092] (summary) A zoom lens according to a first aspect of the present invention is a zoom lens having a plurality of lens groups, in which a lens group arranged closer to the object side than the widest air space between the lens groups at the wide-angle end is defined as a front group, and a lens group arranged closer to the image surface side than the air space is defined as a rear group. The front group is composed of, from the object side, a lens group P having positive refractive power, and an intermediate group M1 including one or more lens groups and having negative refractive power as a whole, and has negative refractive power as a whole. The rear group is composed of, from the object side, a middle group M2 including one or more lens groups and having positive refractive power as a whole, a lens group F having negative refractive power as a whole, and has negative refractive power as a whole. and a rear group R including a lens group, the lens group having positive refractive power overall, during zooming from the wide-angle end to the telephoto end, the interval between adjacent lens groups changes, and the number of lens groups that move so as to change the interval between adjacent lens groups is five or less, the lens group P moves toward the object side, at least one lens group having negative refractive power among the lens groups included in the intermediate group M1 moves gradually toward the image surface side, and at least one lens group having positive refractive power among the lens groups included in the intermediate group M2 moves along a locus convex toward the image surface side, and during focusing, the lens group F moves along the optical axis of the zoom lens, and the following formula is satisfied: 0.5≦bfw / Yw≦1.4 (1) 0.5≦fp / ft≦1.5 (2) -0.9≦fm1 / fw≦-0.15 (3) however, bfw: back focus of the optical system of the zoom lens at the wide-angle end Yw: Maximum image height at the wide-angle end fp: focal length of lens group P ft: focal length of the optical system of the zoom lens at the telephoto end fm1: composite focal length of the intermediate group M1 at the wide-angle end fw: focal length of the optical system of the zoom lens at the wide-angle end

[0093] The zoom lens according to the second aspect of the present invention, in accordance with the first aspect, satisfies the following formula: 0.05≦Dm / Tw≦0.20 (4) Dm: the distance on the optical axis between the intermediate group M1 and the intermediate group M2 at the wide-angle end Tw: Total optical length at the wide-angle end

[0094] The zoom lens according to Aspect 3 of the present invention satisfies the following formula when, in Aspect 1 or Aspect 2, the lens group having the largest negative refractive power among the lens groups having negative refractive power included in the intermediate group M1 is defined as lens group N: 0.5≦|Xp| / |Xn|≦2.0···(5) Xp: the distance on the optical axis between the position of the lens group P at the wide-angle end and the position of the lens group P at the telephoto end Xn: the distance on the optical axis between the position of lens group N at the wide-angle end and the position of lens group N at the telephoto end

[0095] The zoom lens according to Aspect 4 of the present invention, in any one of Aspects 1 to 3, satisfies the following formula: 1.5≦|{1-(βft) 2}×(βrt) 2 |≦9.5···(6) βft: Lateral magnification of lens group F at the telephoto end when focusing at infinity βrt: Lateral magnification of the rear group R at the telephoto end when focusing at infinity

[0096] A zoom lens according to a fifth aspect of the present invention is configured in such a way that, in any one of the first to fourth aspects, the lens unit F moves along a locus that is convex towards the image surface side during zooming from the wide-angle end to the telephoto end.

[0097] The zoom lens according to Aspect 6 of the present invention is based on any one of Aspects 1 to 5, in which the middle group M2 includes a vibration isolation group V having negative refractive power that moves in a direction perpendicular to the optical axis.

[0098] A zoom lens according to aspect 7 of the present invention is configured such that, in aspect 6, the intermediate group M2 includes one or more lenses on the object side of the vibration reduction group V and one or more lenses on the image side of the vibration reduction group V, the lenses in the intermediate group M2 located on the object side of the vibration reduction group V have positive refractive power as a whole, and the lenses in the intermediate group M2 located on the image side of the vibration reduction group V have positive refractive power as a whole.

[0099] The zoom lens according to aspect 8 of the present invention, in accordance with aspect 7, satisfies the following formula: 0.7≦fm2p / fm2≦2.0 (7) fm2p: The composite focal length of all the lenses in the intermediate group M2 located closer to the object than the image stabilization group V at the telephoto end fm2: The composite focal length of the intermediate group M2 at the telephoto end

[0100] The zoom lens according to Aspect 9 of the present invention, in accordance with Aspect 7 or Aspect 8, satisfies the following formula: -3.3≦fm2v / fm2≦-1.2 (8) fm2v: focal length of vibration-isolating group V fm2: The composite focal length of the intermediate group M2 at the telephoto end

[0101] The zoom lens according to Aspect 10 of the present invention is configured in such a way that, in any one of Aspects 1 to 9, the middle group M1 has a convex lens closest to the object side.

[0102] The zoom lens according to embodiment 11 of the present invention is any one of embodiments 1 to 10 in that the rear group R does not move during zooming.

[0103] The zoom lens according to Aspect 12 of the present invention is based on any one of Aspects 1 to 11, in which the lens group F has at least one lens having positive refractive power and at least one lens having negative refractive power.

[0104] An imaging device according to a thirteenth aspect of the present invention includes the zoom lens according to any one of aspects 1 to twelfth, and an imaging element on the image plane side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal. EXAMPLES

[0105] An embodiment of the present invention will be described below. In the following tables, unless otherwise specified, all units of length are "mm", all units of angle of view are "°", and "E+a" is "×10 a ".

[0106] [Example 1] FIG. 1 is a diagram showing an optical configuration of the zoom lens of Example 1 at the wide-angle end during infinity focusing. The zoom lens of Example 1 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with negative refractive power. The first lens group G1 and the second lens group G2 correspond to the front group described above, and the third lens group G3, the fourth lens group G4, and the fifth lens group G5 correspond to the rear group described above. The first lens group G1 corresponds to the lens group P described above. The second lens group G2 corresponds to the intermediate group M1 described above. Moreover, the second lens group G2 corresponds to the lens group N described above. The third lens group G3 corresponds to the intermediate group M2 described above. The fourth lens group G4 corresponds to the lens group F described above. The fifth lens group G5 corresponds to the rear group R described above.

[0107] 1 indicates a CCD sensor. A cover glass CG is disposed between the fifth lens group G5 and the CCD sensor IP. These points are the same as those in the diagrams that show the optical configurations of the other embodiments, and therefore will not be described below.

[0108] In the first embodiment, the zoom lens performs zooming by changing the air gap between adjacent lens groups on the optical axis. The same applies to the following embodiments.

[0109] The arrows in Fig. 1 indicate the direction and manner of movement of each lens group during zooming from the wide-angle end to the telephoto end. As shown in Fig. 1, during zooming from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the object side, the second lens group G2 gradually moves toward the image surface side, the third lens group G3 moves along a convex trajectory toward the image surface side, and the fourth lens group G4 moves along a convex trajectory toward the image surface side. The fifth lens group G5 does not move.

[0110] The zoom lens performs focusing from an object at infinity to an object at a close distance by moving the fourth lens group G4 toward the image plane side.

[0111] The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0112] The configuration of each lens group will be explained below. The first lens group G1 is composed of, from the object side, a cemented lens of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side. The negative mechanical lens is a lens with negative refractive power, and the positive mechanical lens is a lens with positive refractive power.

[0113] The second lens group G2 is composed of, in order from the object side, a positive meniscus lens L4 with a convex surface facing the object side, a negative meniscus lens L5 with a convex surface facing the object side, a negative meniscus lens L6 with a convex surface facing the object side, a positive meniscus lens L7 with a convex surface facing the object side, and a negative meniscus lens L8 with a concave surface facing the object side.

[0114] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L9 with a convex surface facing the object side, a cemented lens of a negative meniscus lens L10 with a convex surface facing the object side and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens of a biconcave lens L12 and a positive meniscus lens L13 with a convex surface facing the object side, a cemented lens of a biconvex lens L14 and a biconcave lens L15, and a biconvex lens L16. The biconvex lens L16 is a glass molded aspheric lens with aspheric surfaces on both sides. Here, the cemented lens of the biconcave lens L12 and the positive meniscus lens L13 corresponds to the vibration isolation group V described above.

[0115] The fourth lens group G4 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0116] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L19 and a negative meniscus lens L20 with its concave surface facing the object side. The negative meniscus lens L20 is a composite resin type aspherical lens with a composite resin film molded into an aspherical shape attached to the object side surface.

[0117] Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. Table 1 shows surface data of the zoom lens.

[0118] In the surface data table for the embodiments of the present invention, "No." indicates the order of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the distance on the optical axis of the lens surface, and "Nd" indicates the refractive index for the d-line (wavelength λ=587.56 nm). "νd" indicates the Abbe number for the d-line (wavelength λ=587.56 nm), and "ASPH" displayed in the column next to the surface number indicates that the lens surface is aspheric. Furthermore, indications such as "d(0)" and "d(5)" in the "d" column indicate that the distance on the optical axis of the lens surface is a variable distance that changes during zooming or focusing.

[0119] In Table 1, Nos. 1 to 5 are surface numbers of the first lens group G1. Nos. 6 to 15 are surface numbers of the second lens group G2. Nos. 16 to 29 are surface numbers of the third lens group G3. Nos. 30 to 32 are surface numbers of the fourth lens group G4. Nos. 33 to 37 are surface numbers of the fifth lens group G5. Nos. 38 and 39 are surface numbers of the cover glass CG.

[0120] [Table 1] No. rd nd νd Object plane ∞ d(0) 1 155.5198 1.5000 1.80610 33.27 2 83.6531 7.1965 1.49700 81.61 3 -1844.7834 0.2000 4 73.3988 6.9834 1.43700 95.10 5 461.0825 d(5) 6 47.5905 4.6723 1.85883 30.00 7 579.8823 0.7769 8 195.9849 1.2000 1.75500 52.32 9 23.4952 5.8813 10 952.5687 1.0000 1.72916 54.67 11 54.2303 0.2000 12 33.1087 3.6676 1.84666 23.78 13 92.4947 3.7917 14 -42.6220 1.0000 2.00069 25.46 15 -206.1433 d(15) 16 S∞ 1.0000 17 38.5110 4.9076 1.74330 49.22 18 745.9337 0.9873 19 44.9383 1.0000 2.00069 25.46 20 20.7729 6.9899 1.59282 68.62 21 320.7119 3.1443 22 -110.5390 0.9000 1.61266 44.46 23 26.1970 3.2065 1.85451 25.15 24 46.4599 1.3500 25 43.7334 8.0145 1.59282 68.62 26 -23.4024 1.1000 1.87070 40.73 27 876.6337 1.5574 28 ASPH 68.9746 4.7794 1.85108 40.12 29 ASPH -46.2047 d(29) 30 1529.6006 2.3821 1.92286 20.88 31 -77.7371 0.8000 1.72916 54.67 32 31.7386 d(32) 33 ASPH 107.0583 4.9111 1.58313 59.46 34 ASPH -62.3810 15.4427 35 ASPH -22.0000 0.2000 1.53610 41.21 36 -24.0197 1.7000 1.90366 31.31 37 -49.6800 d(37) 38 ∞ 2.5000 1.51680 64.20 39∞1.0000 Image plane ∞

[0121] Table 2 shows the specifications of the zoom lens of Example 1. In the specifications, "f" represents the focal length of the zoom lens during infinity focusing, "Fno" represents the F-number, "ω" represents the half angle of view, and "Y" represents the maximum image height.

[0122] [Table 2] Wide-angle end Mid-range Telephoto end f 72.0664 120.0114 174.6514 F No. 2.9104 2.9109 2.9103 ω 16.3157 9.7406 6.7314 Y 21.6330 21.6330 21.6330

[0123] Table 3 shows the distances of each variable interval for an object at infinity. In the table, the unit of distance is mm. Table 4 shows the distances of each variable interval for a shooting distance of 850 mm. In the table, the unit of distance is mm.

[0124] [Table 3] Wide-angle end Mid-range Telephoto end d(0) ∞ ∞ ∞ d(5) 2.0014 35.8998 53.1842 d(15) 27.1298 12.8263 2.0000 d(29) 5.1074 5.4809 2.4998 d(32) 14.5385 11.6183 16.9614 d(37) 17.2805 17.2805 17.2805

[0125] [Table 4] Wide-angle end Mid-range Telephoto end d(0) 678.0000 660.9517 652.1316 d(5) 2.0014 35.8998 53.1842 d(15) 27.1298 12.8263 2.0000 d(29) 7.3781 11.9435 15.1740 d(32) 12.2679 5.1557 4.2873 d(37) 17.2805 17.2805 17.2805

[0126] Table 5 shows the focal length of each lens group constituting the zoom lens of Example 1. In the table, the unit of distance is mm.

[0127] [Table 5] Group number Focal length G1 148.1010 G2 -40.9089 G3 35.8420 G4 -50.4269 G5 -727.7090

[0128] Table 6 shows the aspheric coefficients of the aspheric surfaces in the zoom lens of Example 1. The aspheric coefficients in this table are values ​​when each aspheric shape is defined by the following formula (1).

[0129]

number

[0130] In the above formula, "X" is the amount of displacement of the aspheric surface in the optical axis direction from a reference plane perpendicular to the optical axis, "H" is the height (distance) from the optical axis to the aspheric surface in the direction perpendicular to the optical axis, "r" is the paraxial radius of curvature of the lens surface, "k" is the conic constant (conic coefficient), and "An" (n is an integer) is the n-th order aspheric coefficient.

[0131] [Table 6] No. k A4 A6 28 0.0000 -6.97969E-06 -2.19527E-09 29 0.0000 2.77578E-07 -6.55276E-09 33 0.0000 7.58265E-06 -7.72695E-09 34 0.0000 4.65516E-06 -1.27998E-08 35 0.0000 1.14513E-05 1.27410E-09 No. A8 A10 A12 28 1.07027E-11 -4.77707E-14 0.00000E+00 29 9.34354E-12 -4.50201E-14 0.00000E+00 33 8.97112E-11 -1.49928E-13 0.00000E+00 34 1.10482E-10 -2.02070E-13 0.00000E+00 35 6.82309E-11 -1.12878E-13 0.00000E+00

[0132] 2, 3, and 4 are diagrams showing longitudinal aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at the intermediate distance state, and at the telephoto end during infinity focusing, respectively. The longitudinal aberration diagrams shown in each diagram are, from the left side of the drawing, spherical aberration (mm), astigmatism (mm), and distortion aberration (%), respectively. The same is true for the other examples.

[0133] In the graph showing spherical aberration, the vertical axis is F-number and the horizontal axis is defocus. In the graph showing spherical aberration, the solid line shows spherical aberration at the d-line (wavelength λ=587.56 nm), the chain line shows spherical aberration at the g-line (wavelength λ=435.84 nm), and the dashed line shows spherical aberration at the C-line (wavelength λ=656.28 nm).

[0134] In the diagram showing astigmatism, the vertical axis represents the half angle of view, and the horizontal axis represents the defocus. In the diagram showing astigmatism, the solid line represents the sagittal image plane (ds) for the d-line, and the dashed line represents the meridional image plane (dm) for the d-line.

[0135] In the diagram showing distortion, the vertical axis represents the half angle of view, and the horizontal axis represents %.

[0136] [Example 2] FIG. 5 is a diagram showing an optical configuration of the zoom lens of Example 2 at the wide-angle end during infinity focusing. The zoom lens of Example 2 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The first lens group G1, the second lens group G2, and the third lens group G3 correspond to the front group described above, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the rear group described above. The first lens group G1 corresponds to the lens group P described above. The second lens group G2 and the third lens group G3 correspond to the intermediate group M1 described above. The third lens group G3 corresponds to the lens group N described above. The fourth lens group G4 corresponds to the intermediate group M2 described above. The fifth lens group G5 corresponds to the above-mentioned lens group F. The sixth lens group G6 corresponds to the above-mentioned rear group R.

[0137] The arrows in Fig. 5 indicate the direction and manner of movement of each lens group during zooming from the wide-angle end to the telephoto end. As shown in Fig. 5, during zooming from the wide-angle end to the telephoto end, the first lens group G1 moves gradually toward the object side, the second lens group G2 moves gradually toward the image surface side, the third lens group G3 moves gradually toward the image surface side, the fourth lens group G4 moves along a convex locus toward the image surface side, and the fifth lens group G5 moves along a convex locus toward the image surface side. The sixth lens group G6 does not move.

[0138] The zoom lens performs focusing from an object at infinity to an object at a close distance by moving the fifth lens group G5 toward the image plane side.

[0139] The aperture stop S is disposed adjacent to the object side of the fourth lens group G4.

[0140] The configuration of each lens group will be described below. The first lens group G1 is composed of, from the object side, a cemented lens of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0141] The second lens group G2 is composed of, in order from the object side, a biconvex lens L4, a biconcave lens L5, a biconcave lens L6, and a positive meniscus lens L7 with its convex surface facing the object side.

[0142] The third lens group G3 is composed of a negative meniscus lens L8 with its concave surface facing the object side.

[0143] The fourth lens group G4 is composed of, in order from the object side, a positive meniscus lens L9 with a convex surface facing the object side, a positive meniscus lens L10 with a convex surface facing the object side, a cemented lens in which three lenses, a negative meniscus lens L11 with a convex surface facing the object side, a biconvex lens L12 and a biconcave lens L13, are cemented together, a cemented lens in which a positive meniscus lens L14 with a concave surface facing the object side and a biconcave lens L15 are cemented together, and a biconvex lens L16. The biconvex lens L16 is a glass molded aspheric lens with aspheric shapes on both sides. Here, the cemented lens of the positive meniscus lens L14 and the biconcave lens L15 corresponds to the vibration isolation group V described above.

[0144] The fifth lens group G5 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0145] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L19, a plano-concave lens L20 with its concave surface facing the image side, and a negative meniscus lens L21 with its concave surface facing the object side. The plano-concave lens L20 is a glass molded aspherical lens with aspherical shapes on both sides.

[0146] Next, a numerical example to which specific numerical values ​​of the zoom lens are applied will be described. Table 8 shows surface data of the zoom lens. In Table 8, Nos. 1 to 5 are surface numbers of the first lens group G1. Nos. 6 to 13 are surface numbers of the second lens group G2. Nos. 14 to 15 are surface numbers of the third lens group G3. Nos. 16 to 29 are surface numbers of the fourth lens group G4. Nos. 30 to 32 are surface numbers of the fourth lens group G4. Nos. 33 to 38 are surface numbers of the fourth lens group G4. Nos. 39 and 40 are surface numbers of the cover glass CG.

[0147] [Table 7] No. rd nd νd Object plane∞ d(0) 1 155.3859 1.5000 1.80610 33.27 2 87.9098 7.0000 1.43700 95.10 3 -19712.1002 0.2000 4 88.8134 6.6136 1.49700 81.61 5 1742.4292 d(5) 6 80.2347 3.8385 1.80610 33.27 7 -299.2285 0.2000 8 -1602.0549 1.1000 1.77250 49.60 9 31.8602 4.7478 10 -244.3384 1.0000 1.61800 63.39 11 100.0350 0.2000 12 46.2756 3.3797 1.84666 23.78 13 150.3166 d(13) 14 -44.2237 0.9000 1.87070 40.73 15 -211.5283 d(15) 16 S ∞ 1.0000 17 39.6505 4.5135 1.72916 54.67 18 129.0097 0.2000 19 33.5180 4.8373 1.49700 81.61 20 104.6825 1.2695 21 40.3280 1.2000 1.87070 40.73 22 17.7268 10.8384 1.61800 63.39 23 -52.1009 1.2000 1.92119 23.96 24 70.7502 4.3238 25 -107.9119 3.0681 1.91082 35.25 26 -34.5861 0.8000 1.69680 55.46 27 71.1489 0.5000 28 ASPH 30.8183 4.8708 1.85108 40.12 29 ASPH -108.9359 d(29) 30 371.2133 3.2535 1.92286 20.88 31 -37.0546 0.8000 1.83400 37.34 32 26.9939 d(32) 33 49.3332 5.2127 1.61772 49.81 34 -70.0042 3.2154 35 ASPH ∞ 1.6000 1.58313 59.38 36 ASPH 65.2278 6.6156 37 -24.1077 1.3000 1.92286 20.88 38 -34.8422 d(38) 39 ∞ 2.5000 1.51680 64.20 40∞1.0000 Image plane ∞

[0148] Table 8 shows the specifications of the zoom lens of the second embodiment.

[0149] [Table 8] Wide-angle end Mid-range Telephoto end f 72.0441 119.9950 174.6307 F No. 2.9098 2.9097 2.9108 ω 16.5054 9.7412 6.7336 Y 21.6330 21.6330 21.6330

[0150] Table 9 shows the distances of each variable interval for an object at infinity. Table 10 shows the distances of each variable interval for a shooting distance of 850 mm.

[0151] [Table 9] Wide-angle end Mid-range Telephoto end d(0) ∞ ∞ ∞ d(5) 2.9924 41.9190 59.8382 d(13) 7.3290 7.9924 8.4735 d(15) 27.6167 14.8554 3.0000 d(29) 3.2329 3.5018 2.5020 d(32) 12.4026 9.9675 12.7599 d(38) 23.6280 23.6280 23.6280

[0152] [Table 10] Wide-angle end Mid-range Telephoto end d(0) 678.0000 653.3375 644.9999 d(5) 2.9924 41.9190 59.8382 d(13) 5.9986 5.9094 5.7351 d(15) 28.9471 16.9384 5.7384 d(29) 4.6487 7.7427 11.3729 d(32) 10.9868 5.7266 3.8891 d(38) 23.6280 23.6280 23.6280

[0153] Table 11 shows the focal length of each lens group constituting the zoom lens of the second embodiment.

[0154] [Table 11] Group number Focal length G1 158.7770 G2 -140.1760 G3 -64.3774 G4 34.9860 G5 -38.7204 G6 234.6110

[0155] Table 12 shows the aspheric coefficients of the aspheric surface in the zoom lens of the second embodiment.

[0156] [Table 12] No. k A4 A6 28 0.5351 -9.88774E-06 -2.81003E-09 29 0.0000 5.31930E-06 -2.83356E-09 35 0.0000 1.81838E-05 -4.20016E-08 36 0.0000 1.39207E-05 -3.93743E-08 No. A8 A10 A12 28 7.79768E-12 -4.31679E-14 0.00000E+00 29 1.59763E-11 -4.15133E-14 0.00000E+00 35 2.38986E-10 -1.92096E-13 0.00000E+00 36 1.91980E-10 4.26230E-14 0.00000E+00

[0157] [Example 3] 9 is a diagram showing an optical configuration of the zoom lens of Example 3 at the wide-angle end during infinity focusing. The zoom lens of Example 3 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. The first lens group G1, the second lens group G2, and the third lens group G3 correspond to the front group described above, and the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 correspond to the rear group described above. The first lens group G1 corresponds to the lens group P described above. The second lens group G2 and the third lens group G3 correspond to the middle group M1 described above. The third lens group G3 corresponds to the lens group N described above. The fourth lens group G4 and the fifth lens group G5 correspond to the above-mentioned middle group M2. The sixth lens group G6 corresponds to the above-mentioned lens group F. The seventh lens group G7 corresponds to the above-mentioned rear group R.

[0158] The arrows in Fig. 9 indicate the direction and manner of movement of each lens group during zooming from the wide-angle end to the telephoto end. As shown in Fig. 9, during zooming from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the object side, the second lens group G2 gradually moves toward the image surface side, the third lens group G3 gradually moves toward the image surface side, the fourth lens group G4 moves along a convex locus toward the image surface side, and the sixth lens group G6 gradually moves toward the object side. The fifth lens group G5 and the seventh lens group G7 do not move.

[0159] The zoom lens performs focusing from an object at infinity to an object at a close distance by moving the sixth lens group G6 toward the image plane side.

[0160] The aperture stop S is disposed adjacent to the object side of the fourth lens group G4.

[0161] The configuration of each lens group will be described below. The first lens group G1 is composed of, from the object side, a cemented lens of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0162] The second lens group G2 is composed of, in order from the object side, a biconvex lens L4, a concave lens L5 with its convex surface facing the object side, a biconcave lens L6, and a biconvex lens L7.

[0163] The third lens group G3 is composed of a negative meniscus lens L8 with its concave surface facing the object side.

[0164] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L9, a biconvex lens L10, a cemented lens of a biconvex lens L11 and a biconcave lens L12, and a cemented lens of a biconcave lens L13 and a positive meniscus lens L14 with its convex surface facing the object side. The biconvex lens L9 is a glass molded aspheric lens with aspheric shapes on both sides. Here, the cemented lens of the biconcave lens L13 and the positive meniscus lens L14 corresponds to the vibration isolation group V described above.

[0165] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15 and a cemented lens of a biconvex lens L16 and a biconcave lens L17.

[0166] The sixth lens group G6 is composed of a cemented lens of a biconvex lens L18 and a biconcave lens L19.

[0167] The seventh lens group G7 is composed of, in order from the object side, a biconvex lens L20, a negative meniscus lens L21 with a convex surface facing the object side, and a negative meniscus lens L22 with a concave surface facing the object side. The negative meniscus lens L21 is a glass molded aspherical lens with aspherical shapes on both sides.

[0168] In Table 13, Nos. 1 to 5 are surface numbers of the first lens group G1. Nos. 6 to 13 are surface numbers of the second lens group G2. Nos. 14 to 15 are surface numbers of the third lens group G3. Nos. 16 to 26 are surface numbers of the fourth lens group G4. Nos. 27 to 31 are surface numbers of the fifth lens group G5. Nos. 32 to 34 are surface numbers of the sixth lens group G6. Nos. 35 to 40 are surface numbers of the seventh lens group G7. Nos. 41 and 42 are surface numbers of the cover glass CG.

[0169] [Table 13] No. rd nd νd Object plane ∞ d(0) 1 156.7990 1.5000 1.80610 33.27 2 82.1936 8.5000 1.43700 95.10 3 -386.1731 0.2000 4 65.5052 7.3925 1.49700 81.61 5 325.2379 d(5) 6 118.8050 3.3068 1.80610 33.27 7 -238.8145 0.2000 8 4543.2994 1.1000 1.77250 49.60 9 32.8014 5.5832 10 -75.1944 1.0000 1.61800 63.39 11 167.3735 0.2000 12 58.7908 3.8917 1.84666 23.78 13 -359.8571 d(13) 14 -38.3817 0.9000 1.87070 40.73 15 -276.3938 d(15) 16 S∞ 1.0000 17 73.6770 3.6741 1.77377 47.17 18 ASPH -265.4944 0.2000 19 113.7271 4.1828 1.72916 54.67 20 -89.9583 0.2000 21 63.4557 4.6037 1.49700 81.61 22 -96.5853 1.0000 1.92119 23.96 23 92.4759 2.7000 24 -452.4440 0.9000 1.73037 32.23 25 24.3720 4.8384 1.80518 25.46 26 72.9872 d(26) 27 198.0883 3.2572 1.91082 35.25 28 -72.2124 0.2000 29 59.0048 5.1309 1.59282 68.62 30 -41.1110 1.0000 1.90366 31.31 31 2451.2836 d(31) 32 98.9713 2.4397 1.92286 20.88 33 -368.0850 0.8000 1.91082 35.25 34 33.6233 d(34) 35 47.9002 6.8564 1.62004 36.30 36 -55.7782 0.5432 37 ASPH 5000.0000 1.6000 1.51633 64.06 38 ASPH 44.7227 8.1603 39 -22.9749 1.3000 1.87070 40.73 40 -38.7218 d(40) 41 ∞ 2.5000 1.51680 64.20 42∞1.0000 Image plane ∞

[0170] Table 14 shows the specifications of the zoom lens of the third embodiment.

[0171] [Table 14] Wide-angle end Mid-range Telephoto end f 72.0418 119.9846 174.6295 F No. 2.9098 2.9096 2.9105 ω 16.4071 9.8135 6.7152 Y 21.6330 21.6330 21.6330

[0172] Table 15 shows the distances of each variable interval for an object at infinity. Table 16 shows the distances of each variable interval for a shooting distance of 850 mm.

[0173] [Table 15] Wide-angle end Mid-range Telephoto end d(0) ∞ ∞ ∞ d(5) 1.0000 34.7009 47.3048 d(13) 7.1477 7.8730 9.1476 d(15) 19.8051 13.9775 3.0000 d(26) 12.9935 7.5267 11.4940 d(31) 8.6903 4.1608 2.5033 d(34) 11.3837 15.9131 17.5706 d(40) 19.1188 19.1188 19.1188

[0174] [Table 16] Wide-angle end Mid-range Telephoto end d(0) 678.0000 654.8683 648.0000 d(5) 1.0000 34.7009 47.3048 d(13) 5.3080 5.2064 5.0706 d(15) 21.6449 16.6441 7.0770 d(26) 12.9935 7.5267 11.4940 d(31) 10.5955 10.4743 16.1530 d(34) 9.4784 9.5996 3.9210 d(40) 19.1188 19.1188 19.1188

[0175] Table 17 shows the focal length of each lens group constituting the zoom lens of Example 3.

[0176] [Table 17] Group number Focal length G1 127.0790 G2 -135.5110 G3 -51.2799 G4 60.5976 G5 50.2493 G6 -57.7848 G7 1005.4200

[0177] Table 18 shows the aspheric coefficients of the aspheric surface in the zoom lens of the third embodiment.

[0178] [Table 18] No. k A4 A6 18 0.0000 2.05238E-06 2.45175E-11 37 0.0000 3.38115E-06 2.09052E-09 38 0.0000 1.42791E-07 2.50957E-09 No. A8 A10 A12 18 1.35807E-13 -7.14210E-17 0.00000E+00 37 4.56355E-11 3.47790E-14 0.00000E+00 38 -7.80453E-13 1.96116E-13 0.00000E+00

[0179] [Example 4] FIG. 13 is a diagram showing an optical configuration of the zoom lens of Example 4 at the wide-angle end during infinity focusing. The zoom lens of Example 4 is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, and a sixth lens group G6 with negative refractive power. The first lens group G1 and the second lens group G2 correspond to the front group described above, and the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the rear group described above. The first lens group G1 corresponds to the lens group P described above. The second lens group G2 corresponds to the intermediate group M1 described above. The second lens group G2 corresponds to the lens group N described above. The third lens group G3 corresponds to the intermediate group M2 described above. The fourth lens group G4 corresponds to the lens group F described above. The fifth lens group G5 and the sixth lens group G6 correspond to the rear group R described above.

[0180] The arrows in Fig. 13 indicate the direction and manner of movement of each lens group during zooming from the wide-angle end to the telephoto end. As shown in Fig. 13, during zooming from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the object side, the second lens group G2 gradually moves toward the image surface side, the third lens group G3 moves along a convex trajectory toward the image surface side, the fourth lens group G4 moves along a convex trajectory toward the image surface side, and the fifth lens group G5 gradually moves toward the image surface side. The sixth lens group G6 does not move.

[0181] The zoom lens performs focusing from an object at infinity to an object at a close distance by moving the fourth lens group G4 toward the image plane side.

[0182] The aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0183] The configuration of each lens group will be described below. The first lens group G1 is composed of, from the object side, a cemented lens of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0184] The second lens group G2 is composed of, in order from the object side, a biconvex lens L4, a negative meniscus lens L5 with a convex surface facing the object side, a negative meniscus lens L6 with a convex surface facing the object side, a positive meniscus lens L7 with a convex surface facing the object side, and a negative meniscus lens L8 with a concave surface facing the object side.

[0185] The third lens group G3 is composed of, in order from the object side, a biconvex lens L9, a cemented lens of a negative meniscus lens L10 with a convex surface facing the object side and a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens of a biconcave lens L12 and a positive meniscus lens L13 with a convex surface facing the object side, a cemented lens of a biconvex lens L14 and a biconcave lens L15, and a biconvex lens L16. Here, the cemented lens of the biconcave lens L12 and the positive meniscus lens L13 corresponds to the above-mentioned vibration reduction group V. The biconvex lens L16 is a glass molded aspherical lens with aspherical shapes on both sides.

[0186] The fourth lens group G4 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0187] The fifth lens group G5 is composed of a biconvex lens L19. The biconvex lens L19 is a glass molded aspheric lens having aspheric surfaces on both sides.

[0188] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L20 and a negative meniscus lens L21 with its concave surface facing the object side. The negative meniscus lens L21 is a glass molded aspheric lens with aspheric shapes on both sides.

[0189] In Table 19, Nos. 1 to 5 are surface numbers of the first lens group G1. Nos. 6 to 15 are surface numbers of the second lens group G2. Nos. 16 to 29 are surface numbers of the third lens group G3. Nos. 30 to 32 are surface numbers of the fourth lens group G4. Nos. 33 to 34 are surface numbers of the fifth lens group G5. Nos. 35 to 38 are surface numbers of the sixth lens group G6. Nos. 39 and 40 are surface numbers of the cover glass CG.

[0190] [Table 19] No. rd nd νd Object plane∞ d(0) 1 171.9650 1.5000 1.80610 33.27 2 93.1291 6.8201 1.49700 81.61 3 -1483.9550 0.2000 4 80.4637 6.8272 1.43700 95.10 5 622.0322 d(5) 6 45.2633 4.9255 1.72047 34.71 7 -2246.0592 0.2000 8 218.4195 1.2000 1.75500 52.32 9 25.8982 4.5749 10 423.8887 1.0000 1.65160 58.54 11 61.1858 0.8585 12 35.3924 2.9693 1.92119 23.96 13 64.2551 4.3570 14 -43.3331 1.1000 1.90043 37.37 15 -443.4062 d(15) 16 S ∞ 1.0000 17 49.3230 4.8151 1.72916 54.67 18 -156.5041 0.2000 19 35.8156 1.0000 1.85451 25.15 20 21.2043 4.9420 1.59282 68.62 21 51.5391 4.6542 22 -124.3630 0.9000 1.65412 39.68 23 26.9786 3.0622 1.92119 23.96 24 47.4703 1.5000 25 46.6724 7.1903 1.59282 68.62 26 -24.0601 1.1000 1.91082 35.25 27 274.6914 2.5464 28 ASPH 55.2152 5.8899 1.85108 40.12 29 ASPH -46.4995 d(29) 30 142.4900 1.9607 1.92286 20.88 31 -2722.4094 0.8000 1.75500 52.32 32 29.9088 d(32) 33 ASPH 1000.0000 4.2000 1.58313 59.38 34 ASPH -95.7047 d(34) 35 833.2418 5.0000 1.58144 40.75 36 -53.6976 8.1620 37 ASPH -20.3984 1.8000 1.85108 40.12 38 ASPH -47.8222 d(38) 39 ∞ 2.5000 1.51680 64.20 40∞1.0000 Image plane ∞

[0191] Table 20 shows the specifications of the zoom lens of the fourth embodiment.

[0192] [Table 20] Wide-angle end Mid-range Telephoto end f 72.0452 120.0092 174.6309 F No. 2.9097 2.9103 2.9097 ω 16.4017 9.7407 6.7277 Y 21.6330 21.6330 21.6330

[0193] Table 21 shows the distances of each variable interval for an object at infinity. Table 22 shows the distances of each variable interval for a shooting distance of 850 mm.

[0194] [Table 21] Wide-angle end Mid-range Telephoto end d(0) ∞ ∞ ∞ d(5) 1.0000 39.4216 56.4036 d(15) 27.0392 13.7802 2.0000 d(29) 4.2380 4.8393 2.5023 d(32) 15.8160 13.8347 19.3171 d(34) 3.1299 1.2664 1.0000 d(38) 20.0217 20.0217 20.0217

[0195] [Table 22] Wide-angle end Mid-range Telephoto end d(0) 678.0000 656.0808 648.0000 d(5) 1.0000 39.4216 56.4036 d(15) 27.0392 13.7802 2.0000 d(29) 6.6076 11.6942 15.9665 d(32) 13.4464 6.9798 5.8530 d(34) 3.1299 1.2664 1.0000 d(38) 20.0217 20.0217 20.0217

[0196] Table 23 shows the focal length of each lens group constituting the zoom lens of Example 4.

[0197] [Table 23] Group number Focal length G1 155.8780 G2 -42.2798 G3 36.4842 G4 -54.1607 G5 150.0000 G6 -103.3940

[0198] Table 24 shows the aspheric coefficients of the aspheric surface in the zoom lens of the fourth embodiment.

[0199] [Table 24] No. k A4 A6 28 0.0000 -7.55407E-06 3.96744E-10 29 0.0000 1.09067E-06 -5.52850E-09 33 0.0000 1.76477E-05 -1.32309E-08 34 0.0000 1.57694E-05 -9.35953E-09 37 0.0000 4.54689E-05 -5.99527E-08 38 0.0000 2.75334E-05 -6.79104E-08 No. A8 A10 A12 28 -1.82657E-11 4.77371E-14 0.00000E+00 29 -1.25618E-11 3.79100E-14 0.00000E+00 33 1.09732E-10 -3.97701E-13 0.00000E+00 34 1.23267E-10 -5.07279E-13 0.00000E+00 37 1.64503E-10 -1.85355E-13 0.00000E+00 38 1.30590E-10 -1.61915E-13 0.00000E+00

[0200] Table 25 shows the values ​​calculated by the above-mentioned formulas and the numerical values ​​used in the formulas in Examples 1 to 4.

[0201] [Table 25] Example 1 Example 2 Example 3 Example 4 Conditional expression (1) bfw / Yw 0.921 1.215 1.006 1.048 Conditional expression (2) fp / ft 0.848 0.909 0.728 0.893 Conditional expression (3) fm1 / fw -0.568 -0.577 -0.468 -0.587 Conditional expression (4) Dm / Tw 0.164 0.167 0.122 0.164 Conditional expression (5) |Xp| / |Xn| 1.022 1.321 1.639 1.181 Conditional expression (6) {1-(βft) 2}×(βrt) 2 3.300 3.925 2.394 3.143 Conditional expression (7) fm2p / fm2 1.418 1.569 1.116 1.312 Conditional expression (8) fm2v / fm2 -1.909 -2.361 -2.667 -1.871

[0202] Table 26 shows the values ​​used in the above formulas in Examples 1 to 4.

[0203] [Table 26] Example 1 Example 2 Example 3 Example 4 bfw 19.929 26.276 21.767 22.670 fp 148.101 158.777 127.079 155.878 fm1 -40.909 -41.597 -33.729 -42.280 Dm 28.130 28.617 20.805 28.039 Tw 171.148 171.148 171.148 171.148 |Xp| 25.868 33.000 30.000 30.000 |Xn| 25.314 24.990 18.305 25.404 βft 2.485 3.068 2.196 2.261 βrt 0.799 0.683 0.791 0.874 fm2p 50.819 54.898 43.879 47.858 fm2 35.842 34.986 39.303 36.484 fm2v -68.432 -82.612 -104.820 -68.266 [Explanation of symbols]

[0204] 1. Mirrorless interchangeable-lens camera 2 Main unit 3. Telescope tube 21. IP CCD sensor 22 Coverslip 30 Zoom Lens 31. P lens group P 32, M1 Intermediate group M1 33, M2 Intermediate group M2 34, F lens group F 35, R rear group R CG cover glass G1~G7 lens group OA optical axis S (aperture) aperture

Claims

1. A zoom lens having a plurality of lens groups, When the lens group arranged closer to the object side than the widest air gap between the lens groups at the wide-angle end is defined as the front group, and the lens group arranged closer to the image plane side than the air gap is defined as the rear group, the front group is composed of, in order from the object side, a lens group P having positive refractive power, and an intermediate group M1 including one or more lens groups and having negative refractive power as a whole, and has negative refractive power as a whole; the rear group is composed of, in order from the object side, an intermediate group M2 including one or more lens groups and having positive refractive power as a whole, a lens group F having negative refractive power as a whole, and a rear group R including one or more lens groups and having positive refractive power as a whole; When zooming from the wide-angle end to the telephoto end, The spacing between adjacent lens groups changes, the number of lens groups that move to change the spacing between adjacent lens groups is five or less; The lens group P moves toward the object side, At least one lens group having a negative refractive power among the lens groups included in the intermediate group M1 moves gradually toward the image surface side, and At least one lens group having a positive refractive power among the lens groups included in the intermediate group M2 moves along a locus that is convex toward the image surface side, During focusing, the lens group F moves along the optical axis of the zoom lens, A zoom lens that satisfies the following formula: 0.5≦bfw / Yw≦1.4 (1) 0.5≦fp / ft≦1.5 (2) −0.9≦fm1 / fw≦−0.15 (3) however, bfw: back focus of the optical system of the zoom lens at the wide-angle end Yw: Maximum image height at the wide-angle end fp: focal length of the lens group P ft: focal length of the optical system of the zoom lens at the telephoto end fm1: composite focal length of the intermediate lens unit M1 at the wide-angle end fw: focal length of the optical system of the zoom lens at the wide-angle end

2. 2. The zoom lens of claim 1, wherein the following formula is satisfied: 0.05≦Dm / Tw≦0.20 (4) Dm: the distance on the optical axis between the intermediate lens unit M1 and the intermediate lens unit M2 at the wide-angle end Tw: total optical length at the wide-angle end

3. 2. The zoom lens according to claim 1, wherein the following formula is satisfied, where the lens group having the largest negative refractive power among the lens groups having negative refractive power included in the intermediate group M1 is defined as a lens group N: 0.5≦|Xp| / |Xn|≦2.0...(5) Xp: the distance on the optical axis between the position of the lens group P at the wide-angle end and the position of the lens group P at the telephoto end Xn: the distance on the optical axis between the position of the lens group N at the wide-angle end and the position of the lens group N at the telephoto end

4. 2. The zoom lens of claim 1, wherein the following formula is satisfied: 1.5≦|{1-(βft) ２ }×(βrt) ２ |≦9.5・・・(6) βft: lateral magnification of the lens group F at the telephoto end during infinity focusing βrt: lateral magnification of the rear lens group R at the telephoto end during focusing at infinity

5. 2. The zoom lens according to claim 1, wherein, during zooming from the wide-angle end to the telephoto end, the lens unit F moves along a locus that is convex toward the image surface side.

6. 2. The zoom lens of claim 1, wherein the intermediate group M2 includes a vibration isolation group V having negative refractive power that moves in a direction perpendicular to the optical axis.

7. the intermediate group M2 includes one or more lenses on the object side of the image stabilization group V and one or more lenses on the image surface side of the image stabilization group V, the lenses in the intermediate group M2 that are disposed closer to the object side than the vibration reduction group V have a positive refractive power as a whole, the lenses in the intermediate group M2 that are disposed closer to the image surface side than the vibration reduction group V have a positive refractive power as a whole; 7. The zoom lens according to claim 6.

8. 8. The zoom lens according to claim 7, which satisfies the following formula: 0.7≦fm2p / fm2≦2.0 (7) fm2p: composite focal length at the telephoto end of all lenses in the intermediate group M2 that are arranged closer to the object side than the image stabilization group V fm2: composite focal length of the intermediate group M2 at the telephoto end

9. 8. The zoom lens according to claim 7, which satisfies the following formula: −3.3≦fm2v / fm2≦−1.2 … (8) fm2v: focal length of the vibration isolation group V fm2: composite focal length of the intermediate group M2 at the telephoto end

10. 2. The zoom lens according to claim 1, wherein the lens group F comprises at least one lens having a positive refractive power and at least one lens having a negative refractive power.

11. 11. An imaging device comprising: the zoom lens according to claim 1; and an image sensor, provided on an image plane side of the zoom lens, for converting an optical image formed by the zoom lens into an electrical signal.

Images