Zoom lens and imaging device

Abstract

The present invention addresses the problem of providing a high-performance zoom lens and an imaging device which have a large aperture ratio, are small in size as a whole, and have satisfactorily corrected aberrations. The objective of the present invention is to provide a zoom lens comprising a front group having a negative refractive power as a whole and a rear group having a positive refractive power as a whole, the number of lens groups moving so as to change the interval when zooming from the wide-angle end to the telephoto end being five or less, and having specific optical characteristics represented by a specific formula.

Description

Technical Field

[0001] The invention relates to a zoom lens and a camera device. Background Art

[0002] Image pickup devices such as digital cameras and digital video cameras that use solid-state image pickup elements are becoming more and more popular. Examples of such image pickup devices include digital cameras, digital video cameras, broadcast cameras, surveillance cameras, and vehicle-mounted cameras. Among various image pickup devices, there is a strong market demand for zoom lenses that have a large aperture ratio, a compact optical system, and high optical performance.

[0003] As an optical structure of a zoom lens, for example, a positive-lead type structure is known in which the lens group closest to the object side has positive refractive power. In a positive-lead type zoom lens, a strong negative refractive power is generally configured for the second lens group from the object side, so that the second lens group bears a greater load of zooming, thereby making it easy to achieve high zooming. In such a positive-lead type zoom lens, the telephoto tendency becomes stronger, so the total optical length can be shortened relative to the focal length.

[0004] Among such zoom lenses, there are known zoom lenses that have lens groups with positive / negative / positive / negative / positive power in order from the object side and use the fourth lens group as a focus adjustment group (see, for example, Patent Document 1). In addition, among such zoom lenses, there are known zoom lenses that have lens groups with positive / negative / positive / negative / positive power in order from the object side and use the second lens group as a focus adjustment group (see, for example, Patent Document 2).

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: International Publication No. 2018 / 092295

[0008] Patent Document 2: Japanese Patent Application Publication No. 2019-138941 Summary of the invention

[0009] Problems to be solved by the invention

[0010] Here, in order to obtain a zoom lens with a small F value and high optical performance, it is necessary to well correct various aberrations caused by increasing the aperture ratio. Therefore, in a zoom lens with a small F value, it is difficult to configure a strong optical focal length for each lens group compared to a zoom lens with a large F value, and the optical system tends to be large-scale. In addition, in order to obtain a zoom lens with a small F value, it is preferred to configure a lens group with a strong positive optical focal length on the image side, that is, at the rear of the optical system. However, if a lens group with a strong positive optical focal length is configured at the rear of the optical system, it is difficult to obtain a zoom lens with a strong telephoto tendency and it is difficult to shorten the total optical length. In this way, in order to realize a zoom lens with a larger aperture ratio, high optical performance and a smaller size, it is necessary to appropriately set the optical focal length configuration of each lens group, the imaging magnification, the lens structure, the distance moved by each lens group accompanying the magnification change, etc.

[0011] In the zoom lens described in Patent Document 1, the back focus is long, and it is impossible to achieve miniaturization of the optical system.

[0012] In the zoom lens described in Patent Document 2, in focusing based on the second lens group, since the number of lenses is large and heavy, it is not suitable for rapid focusing. In addition, since the weight of the second lens group is large, the driving mechanism for moving the second lens group during focusing is large. Therefore, there is a problem of enlarging the diameter of the lens barrel.

[0013] An object of one embodiment of the present invention is to provide a high-performance zoom lens and an imaging device that have a large aperture ratio, are compact as a whole, and have various aberrations corrected well.

[0014] Means for solving problems

[0015] In order to solve the above-mentioned problems, a zoom lens according to one embodiment of the present invention includes a plurality of lens groups, wherein:

[0016] When the lens group disposed on the object side relative to the widest air gap between the lens groups at the wide-angle end is the front group, and the lens group disposed on the image plane side relative to the air gap is the rear group,

[0017] The front group is composed of 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, in order from the object side, and has negative refractive power as a whole.

[0018] The rear group is composed of, from the object side, an intermediate group M2 including one or more lens groups and having positive optical power as a whole, a lens group F having negative optical power as a whole, and a rear group R including one or more lens groups and having positive optical power as a whole.

[0019] When zooming from wide angle to telephoto,

[0020] The spacing between adjacent lens groups changes.

[0021] The number of lens groups that are moved so as to change the intervals between adjacent lens groups is 5 or less,

[0022] The lens group P moves toward the object side.

[0023] At least one lens group having negative refractive power among the lens groups included in the middle group M1 is gradually moved toward the image plane side, and,

[0024] At least one lens group having positive refractive power among the lens groups included in the intermediate group M2 moves along a trajectory that is convex toward the image plane.

[0025] When focusing, the lens group F moves along the optical axis of the zoom lens.

[0026] The zoom lens satisfies the following equation:

[0027] 0.5≤bfw / Yw≤1.4···(1)

[0028] 0.5≤fp / ft≤1.5···(2)

[0029] -0.9≤fm1 / fw≤-0.15···(3)

[0030] in,

[0031] bfw: the back focal length of the optical system of the zoom lens at the wide-angle end

[0032] Yw: Maximum image height at wide angle end

[0033] fp: focal length of the lens group P

[0034] ft: focal length of the optical system of the zoom lens at the telephoto end

[0035] fm1: composite focal length of the middle group M1 at the wide-angle end

[0036] fw: focal length of the optical system of the zoom lens at the wide-angle end.

[0037] In order to solve the above-mentioned problems, an imaging device according to one aspect of the present invention includes: the zoom lens; and an imaging element that converts an optical image formed by the zoom lens into an electrical signal on an image plane side of the zoom lens.

[0038] Effects of the Invention

[0039] According to one aspect of the present invention, it is possible to provide a zoom lens and an imaging device that are compact as a whole and have high performance in which various aberrations are well corrected. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a lens cross-sectional view schematically showing the optical structure of the zoom lens according to Example 1 at the wide-angle end.

[0041] Figure 2 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 1 is in the wide-angle end state and focused at infinity.

[0042] Figure 3 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 1 is in a state of intermediate focal length and focused at infinity.

[0043] Figure 4 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 1 is in the telephoto end state and focusing at infinity.

[0044] Figure 5 This is a lens cross-sectional view schematically showing the optical structure of the zoom lens according to Example 2 at the wide-angle end.

[0045] Figure 6 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 2 is in the wide-angle end state and focused at infinity.

[0046] Figure 7 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens of Example 2 is in a state of intermediate focal length and focused at infinity.

[0047] Figure 8 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 2 is in the telephoto end state and focused at infinity.

[0048] Fig. 9 This is a lens cross-sectional view schematically showing the optical structure of the zoom lens of Example 3 at the wide-angle end.

[0049] Fig.10 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 3 is in the wide-angle end state and focused at infinity.

[0050] Fig.11 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 3 is in a state of intermediate focal length and is focused at infinity.

[0051] Fig.12 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 3 is in the telephoto end state and is focused at infinity.

[0052] Fig.13This is a lens cross-sectional view schematically showing the optical structure of the zoom lens of Example 4 at the wide-angle end.

[0053] Fig.14 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 4 is in the wide-angle end state and focused at infinity.

[0054] Fig.15 The diagrams are spherical aberration diagrams, astigmatism diagrams, and distortion diagrams of the zoom lens of Example 4 at an intermediate focal length when focusing at infinity.

[0055] Fig.16 These are diagrams showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 4 is in the telephoto end state and focused at infinity.

[0056] Fig.17 It is a diagram schematically showing an example of the configuration of an imaging device according to an embodiment of the present invention.

[0057] Description of Reference Numerals

[0058] 1 Mirrorless Single-lens Camera

[0059] 2 Main body

[0060] 3. Lens tube

[0061] 21. IP CCD sensor

[0062] 22 Protective glass

[0063] 30 Zoom lens

[0064] 31. P lens group P

[0065] 32. M1 intermediate group M1

[0066] 33. M2 intermediate group M2

[0067] 34. F lens group F

[0068] 35.R rear group R

[0069] CG protection glass

[0070] G1~G7 lens group

[0071] OA optical axis

[0072] S (opening) aperture DETAILED DESCRIPTION

[0073] The following describes an embodiment of a zoom lens and an imaging device according to the present invention. More specifically, the present embodiment relates to a zoom lens and an imaging device suitable for an imaging device using a solid-state imaging element (CCD or CMOS, etc.) such as a digital camera or a digital video camera. The zoom lens and the imaging device described below are one embodiment of the zoom lens and the imaging device according to the present invention, and the zoom lens and the imaging device according to the present invention are not limited to the following embodiment.

[0074] 1. Zoom lens

[0075] 1-1. Optical structure

[0076] The optical structure of a zoom lens according to an embodiment of the present invention is described. The zoom lens according to this embodiment has a plurality of lens groups, which are composed of a front group, which is a set of two or more lens groups arranged on the object side than the air space between the widest lens groups at the wide-angle end, and a rear group, which is a set of three or more lens groups arranged on the image side than the air space. The zoom lens does not include lens groups other than the lens groups included in the front group or the rear group, but may include optical elements that do not have substantial optical power.

[0077] In addition, in this specification, "lens group" means a collection of more than one lens that are linked in the zooming action. The lenses in the lens group move in the zooming action while maintaining the relative positional relationship. The zooming action is performed by changing the interval between the lens groups, and the interval between the lenses belonging to the same lens group does not change in the zooming action.

[0078] In this specification, "the widest air gap between lens groups at the wide-angle end" means, with respect to adjacent lens groups, the gap from the vertex of the image-side lens surface of the lens closest to the image plane included in one lens group to the vertex of the object-side lens surface of the lens closest to the object side included in the other lens group.

[0079] The optical structure of the zoom lens is further described below.

[0080] (1) Front group

[0081] The front group has negative refractive power as a whole. The front group is composed of lens group P and middle group M1 in order from the object side.

[0082] The lens group P is arranged closest to the object side. The lens group P has positive optical power as a whole, and its specific lens structure is not particularly limited. The lens group P can be configured to include two lenses with positive optical power, for example. This structure is preferred from the viewpoint of strengthening the positive optical power in the lens group P. In addition, this structure can achieve a high zoom ratio and strengthen the telephoto tendency at the telephoto end, and is therefore preferred from the viewpoint of miniaturizing the optical system of the zoom lens. In addition, a strong telephoto tendency means that the value of the telephoto ratio shows a smaller value.

[0083] In this specification, the "optical system of the zoom lens" means an optical system including optical elements from the lens closest to the object side to the lens closest to the image plane side. The optical system of the zoom lens may also include optical elements outside the above range, for example, a protective glass that may or may not include an imaging element, or an optical element that cuts off a specific wavelength of light such as an infrared cut filter. In addition, in this specification, the distance from the object side lens surface of the lens closest to the object side on the optical axis of the optical system of the zoom lens to the image plane is referred to as the "total optical length".

[0084] The lens group P preferably includes at least one lens having negative refractive power. This structure is preferred from the viewpoint of realizing a zoom lens having excellent optical performance because it is easy to correct spherical aberration, chromatic aberration, etc.

[0085] The middle group M1 is arranged on the image surface side of the lens group P in the front group. The middle group M1 may be one lens group or a collection of two or more lens groups. The middle group M1 includes one or more lens groups and has negative refractive power as a whole.

[0086] Among the lens groups having negative refractive power included in the middle group M1 , the lens group having the largest negative refractive power is referred to as a lens group N. The specific lens structure of the lens group N is not particularly limited.

[0087] As long as the middle group M1 has negative optical power as a whole, other structures are not particularly limited. For example, in addition to the lens group N, the middle group M1 may also have one or more lens groups with positive or negative optical power. This structure is easy to correct the field curvature and spherical aberration associated with zooming, and is therefore preferred from the perspective of realizing a zoom lens with excellent optical performance. In addition, it is preferred to have a convex lens on the object side of the middle group M1. This structure can reduce the light height of the outermost light of the axial light beam incident on the middle group M2 and the aperture stop described later, and is therefore preferred from the perspective of realizing a zoom lens with a small barrel diameter.

[0088] The front group may be substantially composed of only the lens group P and the intermediate group M1. When the front group further includes a lens group other than the above, the lens group is included in the intermediate group M1.

[0089] (2) Rear group

[0090] The rear group has positive refractive power as a whole. The rear group is composed of the middle group M2, the lens group F and the rear group R in order from the object side.

[0091] The middle group M2 is arranged on the object side of the rear group. The middle group M2 may be a single lens group or a collection of two or more lens groups. The middle group M2 is composed of one or more lens groups and has positive optical power as a whole. The lens structure or lens group structure of the middle group M2 may be appropriately determined within the range in which the middle group M2 has positive optical power as a whole.

[0092] The middle group M2 preferably has a convex lens on the object side. This structure is easy to shorten the total optical length, so it is preferred from the perspective of realizing a small zoom lens. In addition, this structure is easy to reduce the light height of the outermost light of the axial light beam and the peripheral light beam incident on the lens group F, so it is preferred from the perspective of miniaturizing the focusing unit.

[0093] The image-side lens surface of the lens closest to the image plane of the middle group M2 is preferably convex toward the image plane side. This structure is preferable from the viewpoint of realizing a zoom lens with a small F value and a bright brightness.

[0094] The intermediate group M2 moves in a direction orthogonal to the optical axis, and from the perspective of miniaturizing the anti-vibration drive mechanism, an anti-vibration group V having a negative optical power is preferred. The anti-vibration group V may also be composed of multiple lenses, but it is preferred that the anti-vibration group V is composed of a single lens or a cemented lens. This structure is preferred from the perspective of achieving lightweight and miniaturization of the anti-vibration group V.

[0095] When the intermediate group M2 includes the anti-vibration group V, it may include one or more lenses on the object side and the image side of the anti-vibration group V. In this case, it is preferred that the one or more lenses arranged on the object side of the anti-vibration group V in the intermediate group M2 have positive refractive power as a whole, and the one or more lenses arranged on the image side of the anti-vibration group V in the intermediate group M2 have positive refractive power as a whole. This structure is preferred from the viewpoint of miniaturizing the anti-vibration group.

[0096] The lens group F is a lens group disposed on the image plane side of the middle group M2 in the rear group. The lens group F has negative refractive power as a whole.

[0097] The lens group F has negative power as a whole, and its specific lens structure is not particularly limited. It is more preferred to have at least one lens with positive power and at least one lens with negative power. This structure is preferred from the perspective of obtaining a high-performance zoom lens that well corrects various aberrations such as spherical aberration and chromatic aberration at the object distance as a whole.

[0098] The lens group F is particularly preferably composed of only a cemented lens formed by cementing one lens having positive refractive power and one lens having negative refractive power. This structure is preferred from the viewpoint of achieving high-speed autofocusing by reducing the weight of the focus group.

[0099] The lens group F is arranged on the image plane side relative to the intermediate group M2 and is arranged relatively backward in the optical system of the zoom lens. This structure allows the light beam converged by the intermediate group M2 from the object side to be incident on the lens group F, and is therefore preferred from the perspective of reducing the lens diameter of the lens group F and making the lens group F lighter.

[0100] The rear group R is arranged on the image plane side of the lens group F in the rear group. The rear group R has at least one lens group, and more specifically, it can be a collection of one lens group or two or more lens groups. The overall optical focal length of the rear group R is not particularly limited. For example, the rear group R can also be configured to have a positive optical focal length as a whole. This structure is preferred from the viewpoint of reducing the F value of the optical system of the zoom lens. On the other hand, the rear group R can also be configured to have a negative optical focal length as a whole. This structure makes it easy to obtain a zoom lens with a stronger telephoto tendency at the telephoto end, and is therefore preferred from the viewpoint of shortening the total optical length at the telephoto end.

[0101] In the range where the effect of the present embodiment can be obtained, the rear group R may include two or more lens groups. From the viewpoint of shortening the total optical length, the rear group R may be one lens group. From the viewpoint of correcting the field curvature well in the entire zoom range, the rear group R may include two or more lens groups.

[0102] (3) Aperture stop

[0103] The zoom lens may also include an aperture stop. The aperture stop may be arranged adjacent to the intermediate group M2 on the object side of the intermediate group M2, or may be arranged inside the intermediate group M2. The structure in which the aperture stop is arranged adjacent to the object side of the intermediate group M2 enables the entrance pupil position to be arranged closer to the object side than when the aperture stop is arranged inside the intermediate group M2. Therefore, it is easy to reduce the diameter of the peripheral light beam passing through the lens group P at the telephoto end, which is preferred from the viewpoint of easily miniaturizing the diameter of the front lens. In addition, the front lens is the lens that is arranged closest to the object side among the lenses included in the optical system of the zoom lens.

[0104] The aperture stop may be disposed inside the intermediate group M2. This configuration is preferred from the viewpoint of miniaturizing the stop mechanism because the stop diameter can be reduced by the convergence effect of the positive refractive power of the intermediate group M2.

[0105] 1-2. Action

[0106] (1) Zoom

[0107] When zooming from the wide-angle end to the telephoto end or from the telephoto end to the wide-angle end, the zoom lens changes magnification by changing the air interval between adjacent lens groups on the optical axis. In particular, when zooming from the wide-angle end to the telephoto end, the air interval between the front group and the rear group, that is, the air interval between the middle group M1 and the middle group M2, is changed in a decreasing manner.

[0108] When zooming, the number of lens groups that move to change the interval between adjacent lens groups is 5 or less. When the number of lens groups that move when zooming is within this range, the mechanism for moving the lens groups can be simplified, which is preferable from the perspective of miniaturizing the diameter of the lens barrel.

[0109] When zooming from the wide-angle end to the telephoto end, the lens group P moves toward the object side. This action is preferred from the perspective of realizing a compact zoom lens with a short total optical length at the wide-angle end. In addition, when zooming, the action of the lens group P is not particularly limited. For example, when zooming from the wide-angle end to the telephoto end, the lens group P may also move gradually toward the object side. In this specification, "gradual movement" refers to a situation where the lens group moves in one direction. Gradual movement is also referred to as monotonic movement in the technical field.

[0110] When zooming from the wide-angle end to the telephoto end, at least one lens group with negative optical power among the lens groups included in the middle group M1 gradually moves toward the image plane. This action can reduce the light height of the outermost light of the axial light beam incident on the middle group M2 and the aperture stop, so it is preferred from the perspective of realizing a zoom lens with a small lens barrel diameter. In addition, this action is easy to reduce the telephoto ratio, so it is preferred from the perspective of shortening the total optical length at the telephoto end.

[0111] When zooming from the wide-angle end to the telephoto end, at least one lens group having positive optical power among the lens groups included in the middle group M2 moves in a convex trajectory toward the image plane side. That is, when zooming from the wide-angle end to the telephoto end, the lens group moves toward the object side after moving toward the image plane side. In addition, when zooming from the telephoto end to the wide-angle end, the lens group moves toward the image plane side and then further moves toward the object side. This action makes it easy to correct the field curvature well in the entire zoom range, and is therefore preferred from the perspective of obtaining a zoom lens with high optical performance.

[0112] When zooming from the wide angle end to the telephoto end, the lens group F preferably moves in a trajectory that is convex toward the image plane. This operation is preferred because it can suppress the change of the focused image plane accompanying the zooming and it is easy to correct the field curvature well in the entire zoom range.

[0113] The rear group R preferably does not move during zooming. In a zoom lens, by making the rear group R disposed closest to the image plane side as a fixed group, it is easy to make the image plane side of the lens barrel into a sealed structure, etc., and thus it is preferred from the viewpoint of a dustproof structure and a waterproof structure. In addition, by making the rear group R as a fixed group, there is no need for a cam structure for moving the rear group R, and the lens barrel structure can be simplified, and thus it is preferred from the viewpoint of achieving miniaturization of the lens barrel and improving manufacturability.

[0114] (2) Focusing

[0115] When focusing the zoom lens, lens group F moves along the optical axis of the zoom lens. By using lens group F as a focusing group, high-speed automatic focusing can be achieved, so it is preferred from the perspective of reducing the load of the focusing drive system. In addition, by using lens group F as a focusing group, the change of the field angle associated with the movement of the focusing group can be suppressed. Therefore, not only in the case of using the contrast AF method, but also in the case of using the image plane phase difference AF method, a zoom lens suitable for dynamic image shooting, etc., can be obtained, wherein the dynamic image shooting uses a tracking AF function. In addition, the lateral magnification of lens group F takes a value greater than 1, so lens group F moves toward the image plane side when focusing from infinity to a close object.

[0116] When focusing the zoom lens, in addition to the lens group F, a lens group different from the lens group F or a part of the lens group may also move. For example, a so-called floating focusing method may be adopted. This structure is easy to correct aberrations at close objects, and is therefore preferred from the perspective of obtaining a high-performance zoom lens. On the other hand, from the perspective of achieving miniaturization and lightness of the lens barrel, it is particularly preferred that only the lens group F moves during focusing in the zoom lens.

[0117] 1-3. Numerical expressions

[0118] The zoom lens preferably has the above-described configuration and satisfies at least one of the following mathematical expressions.

[0119] 1-3-1. Formula (1)

[0120] 0.5≤bfw / Yw≤1.4···(1)

[0121] in,

[0122] bfw: The back focal length of the optical system of the zoom lens at the wide-angle end

[0123] Yw: Maximum image height at wide angle end

[0124] Formula (1) is a mathematical formula for appropriately defining the ratio of the back focus of the optical system of the zoom lens at the wide-angle end to the maximum image height of the zoom lens at the wide-angle end. Here, when the optical system of the zoom lens includes a cover glass, the back focus bfw is calculated using the cover glass thickness as the air conversion distance. When formula (1) is satisfied, the back focus of the zoom lens at the wide-angle end becomes short, which is preferable from the perspective of achieving miniaturization of the overall length.

[0125] If bfw / Yw is lower than the lower limit in formula (1), the back focus of the zoom lens at the wide-angle end is too short, and the angle of incidence on the imaging surface is too large relative to the inclination angle of the optical axis. Here, on the imaging surface of the imaging element, a focusing lens such as an on-chip microlens is provided in each pixel for effectively receiving light at the incident angle, and the light receiving angle of the on-chip microlens is limited to a specified range. Therefore, if the emission angle from the zoom lens is too large, there is a problem of increased peripheral shading due to mismatching with the on-chip microlens. On the other hand, if bfw / Yw exceeds the upper limit in formula (1), the back focus of the zoom lens at the wide-angle end is too long, and it is sometimes difficult to achieve miniaturization of the overall length of the zoom lens.

[0126] From the viewpoint of miniaturization of the overall length, bfw / Yw is preferably 0.55 or more, more preferably 0.60 or more, further preferably 0.65 or more, further preferably 0.70 or more. In addition, from the viewpoint of miniaturization of the overall length of the zoom lens, bfw / Yw is preferably 1.35 or less, more preferably 1.3 or less, further preferably 1.25 or less.

[0127] 1-3-2. Formula (2)

[0128] 0.5≤fp / ft≤1.5···(2)

[0129] fp: focal length of lens group P

[0130] ft: Focal length of the optical system of the zoom lens at the telephoto end

[0131] Formula (2) is a mathematical formula for appropriately defining the ratio of the focal length of the optical system of the zoom lens at the telephoto end to the focal length of the lens group P. When formula (2) is satisfied, the focal length of the lens group P is within an appropriate range relative to the focal length of the optical system of the zoom lens at the telephoto end, and is therefore preferred from the perspective of realizing a small zoom lens with a small telephoto ratio. In addition, when formula (2) is satisfied, the focal length of the lens group P is within an appropriate range, and thus spherical aberration or axial chromatic aberration can be better corrected, and is preferred from the perspective of realizing a zoom lens with good optical performance.

[0132] If fp / ft is lower than the lower limit in formula (2), the focal power of lens group P is sometimes too strong relative to the focal length of the optical system of the zoom lens at the telephoto end. In this case, it is difficult to correct spherical aberration and axial chromatic aberration well, and it is sometimes difficult to achieve a zoom lens with high optical performance. On the other hand, if fp / ft exceeds the upper limit in formula (2), the focal power of lens group P is sometimes too weak relative to 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 longer, and it is sometimes difficult to achieve a small zoom lens with a small telephoto ratio.

[0133] From the viewpoint of correcting spherical aberration and axial chromatic aberration well, fp / ft is preferably 1.3 or less, more preferably 1.2 or less, further preferably 1.1 or less, and further preferably 1.0 or less. In addition, 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, further preferably 0.65 or more, and further preferably 0.70 or more.

[0134] 1-3-3. Formula (3)

[0135] -0.9≤fm1 / fw≤-0.15···(3)

[0136] fm1: composite focal length of the middle group M1 at the wide-angle end

[0137] fw: focal length of the optical system of the zoom lens at the wide-angle end

[0138] Formula (3) is a mathematical formula that appropriately specifies the ratio of the focal length of the optical system of the zoom lens at the wide-angle end to the composite focal length of the intermediate group M1 at the wide-angle end. By satisfying Formula (3), the composite focal length of the intermediate group M1 at the wide-angle end is within an appropriate range relative to the focal length of the optical system of the zoom lens at the wide-angle end, and the field curvature that is easily generated at the wide-angle end can be better corrected. Therefore, it is preferred from the perspective of realizing a zoom lens with good optical performance in 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.

[0139] If fm1 / fw is lower than the lower limit in formula (3), the optical power of the middle group M1 at the wide-angle end as a whole becomes smaller relative to the focal length of the optical system of the zoom lens at the wide-angle end. In this case, it is difficult to reduce the telephoto ratio, so it is sometimes difficult to obtain a small zoom lens with a short total optical length. On the other hand, if fm1 / fw exceeds the upper limit in formula (3), the optical power of the middle group M1 at the wide-angle end as a whole becomes larger relative to the focal length of the optical system of the zoom lens at the wide-angle end. In this case, field curvature is easily generated at the wide-angle end, and it is sometimes difficult to achieve a zoom lens with high optical performance in the entire zoom range.

[0140] From the viewpoint of realizing a zoom lens with high optical performance and well corrected curvature of field, fm1 / fw is preferably -0.20 or less, more preferably -0.25 or less, further preferably -0.30 or less, and further preferably -0.35 or less. From the viewpoint of realizing a compact zoom lens with a short total optical length, fm1 / fw is preferably -0.85 or more, more preferably -0.80 or more, further preferably -0.75 or more, and further preferably -0.70 or more.

[0141] 1-3-4. Formula (4)

[0142] 0.05≤Dm / Tw≤0.20···(4)

[0143] Dm: The distance between the middle group M1 and the middle group M2 on the optical axis at the wide-angle end

[0144] Tw: Total optical length at wide angle end

[0145] Formula (4) is a mathematical formula for appropriately defining the ratio of the total optical length at the wide-angle end to the distance on the optical axis between the intermediate group M1 and the intermediate 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 using the thickness of the cover glass as the air-converted distance. When formula (4) is satisfied, the distance on the optical axis between the intermediate group M1 and the intermediate group M2 at the wide-angle end is within an appropriate range relative to the total optical length at the wide-angle end, and is therefore preferred from the perspective of realizing a zoom lens with a short total length at the wide-angle end.

[0146] If Dm / Tw is lower than the lower limit in formula (4), the distance between the middle group M1 and the middle group M2 on the optical axis at the wide-angle end is sometimes too short relative to the total optical length at the wide-angle end. In this case, it is difficult to fully ensure the movement of the middle group M1 accompanying zooming, so in order to ensure the desired zoom ratio, it is necessary to increase the space in which the lens group P can move. As a result, the total optical length at the telephoto end becomes longer, so it is sometimes difficult to obtain a small zoom lens with a small telephoto ratio. If Dm / Tw exceeds the upper limit in formula (4), the distance between the middle group M1 and the middle group M2 on the optical axis at the wide-angle end becomes longer relative to the total optical length at the wide-angle end, and it is sometimes difficult to obtain a zoom lens with a short total length at the wide-angle end. In addition, if Dm / Tw exceeds the upper limit in formula (4), the light height of the outermost light of the axial light beam incident on the middle group M2 and the aperture stop tends to become larger, and it is sometimes difficult to reduce the diameter of the lens barrel.

[0147] From the viewpoint of miniaturization, Dm / Tw is preferably 0.195 or less, more preferably 0.19 or less, further preferably 1.85 or less, further preferably 0.18 or less. In addition, 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, further preferably 0.08 or more, further preferably 0.09 or more.

[0148] 1-3-5. Formula (5)

[0149] 0.5≤|Xp| / |Xn|≤2.0···(5)

[0150] 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

[0151] 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

[0152] Formula (5) is a mathematical formula for appropriately defining the ratio of 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, and 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. That is, Formula (5) defines the relationship between the distances that the lens group N and the lens group P move from the wide angle end to the telephoto end when zooming.

[0153] When equation (5) is satisfied, the ratio of the distances moved by lens group P and lens group N during zooming is within an appropriate range, which is preferable from the perspective of realizing a compact zoom lens having a short total length and a small barrel diameter at the telephoto end.

[0154] If |Xp| / |Xn| is lower than the lower limit in formula (5), the distance that lens group P moves when zooming is sometimes too small relative to the distance that lens group N moves when zooming. In this case, in order to obtain the desired zoom ratio, it is necessary to increase the distance that lens group N moves. In order to increase the distance that lens group N moves, it is necessary to increase the air gap between intermediate group M1 and intermediate group M2 on the optical axis at the wide-angle end. As a result, the total optical length at the wide-angle end becomes longer, and sometimes it is difficult to obtain a zoom lens with a short total length. If |Xp| / |Xn| exceeds the upper limit in formula (5), the distance that lens group P moves when zooming is sometimes too large relative to the distance that lens group N moves when zooming. In this case, it is difficult to shorten the total optical length at the telephoto end, and therefore it is sometimes difficult to obtain a small zoom lens with a small telephoto ratio.

[0155] 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, further preferably 1.7 or less, and further preferably 1.5 or less. From the viewpoint of obtaining a zoom lens with a short total length, |Xp| / |Xn| is preferably 0.55 or more, more preferably 0.60 or more, further preferably 0.65 or more, and further preferably 0.70 or more.

[0156] 1-3-6. Formula (6)

[0157] 1.5≤|{1-(βft) 2}×(βrt) 2 |≤9.5···(6)

[0158] βft: lateral magnification of lens group F at the telephoto end when focusing at infinity

[0159] βrt: Horizontal magnification of the rear group R at the telephoto end when focusing at infinity

[0160] Formula (6) represents the ratio of the distance moved by the focus plane to the distance moved by the lens group F, and is a formula for setting the position sensitivity of the lens group F within an appropriate range. When formula (6) is satisfied, it is preferable from the viewpoint of making the driving accuracy during focusing appropriate and making the distance moved during focusing appropriate.

[0161] If |{1-(βft) 2}×(βrt) 2 | is lower than the lower limit in equation (6), the distance that lens group F moves during focusing increases, which sometimes leads to an increase in the size of the focus actuator used to drive it. In this case, it is difficult to realize a small zoom lens. 2}×(βrt) 2 If the upper limit of formula (6) is exceeded, the position sensitivity of lens group F becomes too large, the required driving accuracy of focusing becomes high, and it is sometimes difficult to improve the focusing accuracy.

[0162] From the perspective of improving focusing accuracy, |{1-(βft) 2}×(βrt) 2 | is preferably 9.0 or less, more preferably 8.5 or less, further preferably 8.0 or less, further preferably 7.5 or less. In addition, from the perspective of miniaturization of the zoom lens, |{1-(βft) 2}×(βrt) 2 | It is preferably 1.7 or more, more preferably 1.9 or more, further preferably 2.1 or more, and further preferably 2.3 or more.

[0163] 1-3-7. Formula (7)

[0164] 0.7≤fm2p / fm2≤2.0···(7)

[0165] fm2p: The combined focal length of all the lenses in the middle group M2 that are arranged on the object side relative to the anti-vibration group V at the telephoto end

[0166] fm2: composite focal length of the middle group M2 at the telephoto end

[0167] Formula (7) is a numerical formula for appropriately defining the ratio of the composite focal length of the intermediate group M2 at the telephoto end to the composite focal length at the telephoto end of all the lenses in the intermediate group M2 arranged on the object side relative to the anti-vibration group V. When formula (7) is satisfied, the light height of the outermost light of the axial light beam incident on the anti-vibration group V becomes low, which is preferable from the viewpoint of suppressing the enlargement of the anti-vibration drive mechanism.

[0168] If fm2p / fm2 is lower than the lower limit in formula (7), the optical power of the entire lens arranged on the object side of the anti-vibration group V in the intermediate group M2 at the telephoto end may be too strong relative to the synthetic focal length of the intermediate group M2 at the telephoto end. In this case, it may be difficult to properly correct spherical aberration or axial chromatic aberration. If fm2p / fm2 exceeds the upper limit in formula (7), it is difficult to reduce the light height of the outermost light of the axial light beam incident on the anti-vibration group V, which may lead to an increase in the size of the anti-vibration drive mechanism.

[0169] From the viewpoint of miniaturization of the anti-vibration drive mechanism, fm2p / fm2 is preferably 1.9 or less, more preferably 1.8 or less, further preferably 1.7 or less, further preferably 1.6 or less. In addition, from the viewpoint of good correction of spherical aberration or axial chromatic aberration, fm2p / fm2 is preferably 0.8 or more, more preferably 0.9 or more, further preferably 1.0 or more, further preferably 1.1 or more.

[0170] 1-3-8. Formula (8)

[0171] -3.3≤fm2v / fm2≤-1.2···(8)

[0172] fm2v: Focal length of anti-vibration group V

[0173] Formula (8) is a mathematical formula for appropriately defining the ratio of the composite focal length of the intermediate group M2 at the telephoto end to the focal length of the anti-vibration group V. When formula (8) is satisfied, it is preferable from the viewpoint of controlling the drive amplitude of the anti-vibration group V during anti-vibration to be within an appropriate range and suppressing aberrations generated during anti-vibration.

[0174] If fm2v / fm2 is lower than the lower limit in formula (8), the drive amplitude of the anti-vibration group V for anti-vibration correction becomes smaller, which is conducive to miniaturization of the anti-vibration drive mechanism, but it is sometimes difficult to correct spherical aberration and astigmatism during anti-vibration. On the other hand, if fm2v / fm2 exceeds the upper limit in formula (8), the drive amplitude of the anti-vibration group V for anti-vibration correction becomes larger, which leads to the enlargement of the anti-vibration drive mechanism, and it is sometimes difficult to achieve miniaturization of the optical system of the zoom lens.

[0175] From the viewpoint of miniaturization of the zoom lens, fm2v / fm2 is preferably -1.3 or less, more preferably -1.4 or less, further preferably -1.5 or less, further preferably -1.6 or less. In addition, from the viewpoint of correcting spherical aberration and astigmatism during vibration prevention, fm2v / fm2 is preferably -3.2 or more, more preferably -3.0 or more, further preferably -2.9 or more, further preferably -2.8 or more.

[0176] 2. Camera device

[0177] Next, an imaging device according to an embodiment of the present invention is described. The imaging device includes the zoom lens according to the present embodiment described above, and an imaging element provided on the image plane side of the zoom lens and converting an optical image formed by the zoom lens into an electrical signal.

[0178] Here, the imaging element is not limited. Among the imaging elements, solid-state imaging elements such as CCD (Charge Coupled Device) sensors and CMOS (Complementary Metal Oxide Semiconductor) sensors can be used, and silver halide films, infrared cut filters (IRCF), etc. can also be used. The imaging device involved in this embodiment is suitable for imaging devices such as digital cameras and video cameras that use the above-mentioned solid-state imaging elements. In addition, the imaging device can be a fixed-lens imaging device in which the lens (lens) is fixed to the housing, or a replaceable lens imaging device such as a single-lens reflex camera and a mirrorless single-lens camera. In particular, the zoom lens involved in this embodiment can ensure a back focus suitable for a replaceable lens system. Therefore, it is suitable for imaging devices such as single-lens reflex cameras that have an optical viewfinder, a phase difference sensor, and a reflector for branching light to these components.

[0179] Fig.17 Schematically shows an example of the structure of the imaging device according to the present embodiment. Fig.17 As shown, the mirrorless single-lens camera 1 includes a main body 2 and a lens barrel 3 that is attachable to and detachable from the main body 2. The mirrorless single-lens camera 1 is one form of an imaging device.

[0180] 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 the above equations (1) to (3), for example. In addition, a stop S is arranged on the object side of the third lens group 33.

[0181] The first lens group 31 has a positive optical power as a whole, and is equivalent to the above-mentioned lens group P. The second lens group 32 has a negative optical power as a whole, and is equivalent to the above-mentioned intermediate group M1. The third lens group 33 has a positive optical power as a whole, and is equivalent to the above-mentioned intermediate group M2. The fourth lens group 34 has a negative optical power as a whole, and is equivalent to the above-mentioned lens group F. The fifth lens group 35 has a negative optical power as a whole, and is equivalent to the above-mentioned rear group R.

[0182] The main body 2 has a CCD sensor 21 as an imaging element and a protective glass 22. The CCD sensor 21 is arranged in a position in the main body 2 such that the optical axis OA of the zoom lens 30 installed in the lens barrel 3 of the main body 2 becomes the central axis. The main body 2 may also have a parallel plane plate having no substantial optical power, such as an infrared cut filter (IRCF), instead of the protective glass 22.

[0183] Since the mirrorless single-lens camera 1 includes the zoom lens 30 , it is possible to be compact as a whole and to capture a high-quality image in which various aberrations are well corrected.

[0184] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0185] (Summary)

[0186] The zoom lens according to the first aspect of the present invention has a plurality of lens groups, wherein, when a lens group disposed on the object side relative to the widest air gap between lens groups at a wide-angle end is a front group, and a lens group disposed on the image plane side relative to the air gap is a rear group, the front group is composed, in order from the object side, of a lens group P having positive power and an intermediate group M1 including one or more lens groups and having negative power as a whole, and having negative power as a whole, and the rear group is composed, in order from the object side, of an intermediate group M2 including one or more lens groups and having positive power as a whole, a lens group F having negative power as a whole, and an intermediate group M3 including one or more lens groups and having positive power as a whole. The zoom lens is composed of a rear group R of more than one lens group, and has positive optical power as a whole. When zooming from the wide-angle end to the telephoto end, the intervals between adjacent lens groups change, and the number of lens groups that move in a manner that changes the intervals between adjacent lens groups is less than 5, the lens group P moves toward the object side, at least one lens group with negative optical power among the lens groups included in the middle group M1 gradually moves toward the image plane side, and at least one lens group with positive optical power among the lens groups included in the middle group M2 moves in a convex trajectory toward the image plane side. When focusing, the lens group F moves along the optical axis of the zoom lens, and the zoom lens satisfies the following formula:

[0187] 0.5≤bfw / Yw≤1.4···(1)

[0188] 0.5≤fp / ft≤1.5···(2)

[0189] -0.9≤fm1 / fw≤-0.15···(3)

[0190] in,

[0191] bfw: the back focal length of the optical system of the zoom lens at the wide-angle end

[0192] Yw: Maximum image height at wide angle end

[0193] fp: focal length of lens group P

[0194] ft: focal length of the optical system of the zoom lens at the telephoto end

[0195] fm1: composite focal length of the middle group M1 at the wide-angle end

[0196] fw: focal length of the optical system of the zoom lens at the wide-angle end.

[0197] The zoom lens according to aspect 2 of the present invention satisfies the following equation in aspect 1:

[0198] 0.05≤Dm / Tw≤0.20···(4)

[0199] Dm: The distance between the middle group M1 and the middle group M2 on the optical axis at the wide-angle end

[0200] Tw: Total optical length at the wide-angle end.

[0201] The zoom lens according to aspect 3 of the present invention satisfies the following formula in aspect 1 or aspect 2 when the lens group having the largest negative refractive power among the lens groups having negative refractive power included in the middle group M1 is used as the lens group N:

[0202] 0.5≤|Xp| / |Xn|≤2.0···(5)

[0203] 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

[0204] 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.

[0205] The zoom lens according to aspect 4 of the present invention satisfies the following formula in any one of aspects 1 to 3:

[0206] 1.5≤|{1-(βft) 2}×(βrt) 2 |≤9.5···(6)

[0207] βft: lateral magnification of lens group F at the telephoto end when focusing at infinity

[0208] βrt: Horizontal magnification of the rear group R at the telephoto end when focusing at infinity.

[0209] The zoom lens according to aspect 5 of the present invention is any one of aspects 1 to 4, wherein the lens group F moves along a locus that is convex toward the image plane when zooming from the wide-angle end to the telephoto end.

[0210] The zoom lens according to aspect 6 of the present invention is one of aspects 1 to 5, wherein the intermediate group M2 includes an anti-vibration group V that moves in a direction orthogonal to the optical axis and has negative refractive power.

[0211] The zoom lens involved in mode 7 of the present invention is in mode 6, wherein the intermediate group M2 includes one or more lenses on the object side and the image plane side relative to the anti-vibration group V, respectively, and the lenses arranged on the object side relative to the anti-vibration group V in the intermediate group M2 have positive optical focal length as a whole, and the lenses arranged on the image plane side relative to the anti-vibration group V in the intermediate group M2 have positive optical focal length as a whole.

[0212] The zoom lens according to aspect 8 of the present invention satisfies the following formula in aspect 7:

[0213] 0.7≤fm2p / fm2≤2.0···(7)

[0214] fm2p: The combined focal length of all the lenses in the middle group M2 that are arranged on the object side relative to the anti-vibration group V at the telephoto end

[0215] fm2: The composite focal length of the middle group M2 at the telephoto end.

[0216] The zoom lens according to aspect 9 of the present invention satisfies the following formula in aspect 7 or aspect 8:

[0217] -3.3≤fm2v / fm2≤-1.2···(8)

[0218] fm2v: Focal length of anti-vibration group V

[0219] fm2: The composite focal length of the middle group M2 at the telephoto end.

[0220] The zoom lens according to aspect 10 of the present invention is any one of aspects 1 to 9, wherein the intermediate group M1 includes a convex lens on the most object side.

[0221] In the zoom lens according to aspect 11 of the present invention, in any one of aspects 1 to 10, the rear group R does not move during zooming.

[0222] The zoom lens according to aspect 12 of the present invention is any one of aspects 1 to 11, wherein the lens group F includes at least one lens having positive refractive power and at least one lens having negative refractive power.

[0223] An imaging device according to aspect 13 of the present invention comprises: the zoom lens according to any one of aspects 1 to 12; and an imaging element for converting an optical image formed by the zoom lens into an electrical signal on the image plane side of the zoom lens.

[0224] [Example]

[0225] The following is a description of an embodiment of the present invention. In the following tables, unless otherwise specified, the unit of length is "mm", the unit of field angle is "°", and "E+a" means "×10 a ”.

[0226] [Example 1]

[0227] Figure 1: This is a diagram schematically showing the optical structure of the zoom lens of Example 1 at the wide-angle end when focusing at infinity. The zoom lens of Example 1 is composed of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with negative optical power, and a fifth lens group G5 with negative optical power, in order from the object side. The first lens group G1 and the second lens group G2 are equivalent to the above-mentioned front group, and the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are equivalent to the above-mentioned rear group. The first lens group G1 is equivalent to the above-mentioned lens group P. The second lens group G2 is equivalent to the above-mentioned middle group M1. In addition, the second lens group G2 is equivalent to the above-mentioned lens group N. The third lens group G3 is equivalent to the above-mentioned middle group M2. The fourth lens group G4 is equivalent to the above-mentioned lens group F. The fifth lens group G5 is equivalent to the above-mentioned rear group R.

[0228] in addition, Figure 1 The "IP" shown is a CCD sensor. In addition, a protective glass CG is arranged between the fifth lens group G5 and the CCD sensor IP. These points are also the same in the figures schematically showing the optical structures shown in other embodiments, so the description is omitted below.

[0229] In Example 1, the zoom lens performs zooming by changing the air space on the optical axis between adjacent lens groups. The same is true in the following embodiments.

[0230] Figure 1 The arrows in the figure indicate the direction and mode of movement of each lens group when zooming from the wide-angle end to the telephoto end. Figure 1 As shown, when 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 plane side, the third lens group G3 moves in a convex shape toward the image plane side, and the fourth lens group G4 moves in a convex shape toward the image plane side. The fifth lens group G5 does not move.

[0231] By moving the fourth lens group G4 toward the image plane, the zoom lens focuses from an object at infinity to an object at a close distance.

[0232] The aperture stop S is arranged adjacent to the object side of the third lens group G3.

[0233] The structure of each lens group is described below. The first lens group G1 is composed of a negative meniscus lens L1 with a convex surface facing the object side and a cemented lens of a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side, starting from the object side. In addition, the negative meniscus lens is a lens with negative optical power, and the positive meniscus lens is a lens with positive optical power.

[0234] The second lens group G2 is composed, from the object side, in sequence: a positive meniscus lens L4 with its convex surface facing the object side, a negative meniscus lens L5 with its convex surface facing the object side, a negative meniscus lens L6 with its convex surface facing the object side, a positive meniscus lens L7 with its convex surface facing the object side, and a negative meniscus lens L8 with its concave surface facing the object side.

[0235] The third lens group G3 is composed of, 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 mold-cast aspheric lens with both surfaces set to an aspheric shape. Here, the cemented lens of the biconcave lens L12 and the positive meniscus lens L13 is equivalent to the above-mentioned anti-vibration group V.

[0236] The fourth lens group G4 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0237] The fifth lens group G5 is composed of a biconvex lens L19 and a negative meniscus lens L20 with a concave surface facing the object side in order from the object side. The negative meniscus lens L20 is a composite resin type aspherical lens having a composite resin film molded into an aspherical shape attached to the object side.

[0238] Next, numerical examples of the zoom lens to which specific numerical values ​​are applied are described. Table 1 shows surface data of the zoom lens.

[0239] Furthermore, in the table of surface data in the embodiment of the present invention, "No." indicates the serial number of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the interval between the lens surfaces on the optical axis, and "Nd" indicates the refractive index corresponding to the d-line (wavelength λ = 587.56 nm). In addition, "νd" indicates the Abbe number corresponding to 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 an aspherical surface. Furthermore, the marks such as "d(0)" and "d(5)" in the "d" column mean that the interval between the lens surfaces on the optical axis is a variable interval that changes when zooming or focusing.

[0240] In Table 1, numbers 1 to 5 are the surface numbers of the first lens group G1. Numbers 6 to 15 are the surface numbers of the second lens group G2. Numbers 16 to 29 are the surface numbers of the third lens group G3. Numbers 30 to 32 are the surface numbers of the fourth lens group G4. Numbers 33 to 37 are the surface numbers of the fifth lens group G5. Numbers 38 and 39 are the surface numbers of the protective glass CG.

[0241] [Table 1]

[0242]

[0243]

[0244]

[0245] Table 2 shows the elements of the zoom lens of Example 1. In the element table, "f" represents the focal length of the zoom lens when focusing at infinity, "Fno" represents the F value, "ω" represents the half angle of view, and "Y" represents the maximum image height.

[0246] [Table 2]

[0247]

[0248]

[0249] Table 3 shows the distances of the variable intervals at an infinitely distant object. In the table, the unit of the distance is mm. Table 4 shows the distances of the variable intervals at a photographic distance of 850 mm. In the table, the unit of the distance is mm.

[0250] [Table 3]

[0251] Wide-angle end middle 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

[0252] [Table 4]

[0253] Wide-angle end middle 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

[0254] Table 5 is a table showing the focal lengths of the lens units constituting the zoom lens of Example 1. In the table, the unit of distance is mm.

[0255] [Table 5]

[0256] Group Number focal length G1 148.1010 G2 -40.9089 G3 35.8420 G4 -50.4269 G5 -727.7090

[0257] Table 6 shows the aspherical coefficients of the aspherical surface in the zoom lens of Example 1. The aspherical coefficients in this table are values ​​when the shape of each aspherical surface is defined by the following equation (1).

[0258] [Formula 1]

[0259]

[0260] In the above formula, "X" is the displacement of the aspheric surface in the direction of the optical axis relative to the 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 curvature radius of the lens surface, "k" is the cone constant (cone coefficient), and "An" (n is an integer) is the n-th order aspheric coefficient.

[0261] [Table 6]

[0262]

[0263]

[0264] in addition, Figure 2 , 3 4 are diagrams showing longitudinal aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate distance state, and the infinity focus at the telephoto end. The longitudinal aberration diagrams shown in the respective figures are spherical aberration (mm), astigmatism (mm), and distortion (%), respectively, from the left side of the drawings. The same is true for the other embodiments.

[0265] In the graph showing spherical aberration, the vertical axis is set to F value and the horizontal axis is set to defocus. In the graph showing spherical aberration, the solid line represents the spherical aberration at the d-line (wavelength λ=587.56nm), the dashed line represents the spherical aberration at the g-line (wavelength λ=435.84nm), and the dotted line represents the spherical aberration at the C-line (wavelength λ=656.28nm).

[0266] In the diagram showing astigmatism, the vertical axis represents the half field angle and the horizontal axis represents defocus. In the diagram showing astigmatism, the solid line represents the sagittal image plane (ds) corresponding to the d-line and the dotted line represents the meridional image plane (dm) corresponding to the d-line.

[0267] In the graph showing distortion, the vertical axis represents the half angle of view, and the horizontal axis represents %.

[0268] [Example 2]

[0269] Figure 5 : This is a diagram schematically showing the optical structure of the zoom lens of Example 2 at the wide-angle end when focusing at infinity. The zoom lens of Example 2 is composed of, from the object side, a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with negative optical power, a fourth lens group G4 with positive optical power, a fifth lens group G5 with negative optical power, and a sixth lens group G6 with positive optical power. The first lens group G1, the second lens group G2, and the third lens group G3 are equivalent to the above-mentioned front group, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 are equivalent to the above-mentioned rear group. The first lens group G1 is equivalent to the above-mentioned lens group P. The second lens group G2 and the third lens group G3 are equivalent to the above-mentioned intermediate group M1. In addition, the third lens group G3 is equivalent to the above-mentioned lens group N. The fourth lens group G4 is equivalent to the above-mentioned intermediate group M2. The fifth lens group G5 is equivalent to the above-mentioned lens group F. The sixth lens group G6 corresponds to the rear group R mentioned above.

[0270] Figure 5 The arrows in the figure indicate the direction and mode of movement of each lens group when zooming from the wide-angle end to the telephoto end. Figure 5 As shown, when 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 plane side, the third lens group G3 gradually moves toward the image plane side, the fourth lens group G4 moves in a convex shape toward the image plane side, and the fifth lens group G5 moves in a convex shape toward the image plane side. The sixth lens group G6 does not move.

[0271] By moving the fifth lens group G5 toward the image plane, the zoom lens focuses from an object at infinity to an object at a close distance.

[0272] The aperture stop S is arranged adjacent to the object side of the fourth lens group G4.

[0273] The first lens group G1 is composed of, in order 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.

[0274] 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 a convex surface facing the object side.

[0275] The third lens group G3 is composed of a negative meniscus lens L8 having a concave surface facing the object side.

[0276] The fourth lens group G4 is composed of, 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 formed by cementing three lenses, namely, a negative meniscus lens L11 with a convex surface facing the object side, a biconvex lens L12 and a biconcave lens L13, a cemented lens of a positive meniscus lens L14 and a biconcave lens L15 with a concave surface facing the object side, and a biconvex lens L16. The biconvex lens L16 is a glass molded aspheric lens with both surfaces set to an aspheric shape. Here, the cemented lens of the positive meniscus lens L14 and the biconcave lens L15 is equivalent to the above-mentioned anti-vibration group V.

[0277] The fifth lens group G5 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0278] The sixth lens group G6 is composed of a biconvex lens L19, a plano-concave lens L20 with a concave surface facing the image side, and a negative meniscus lens L21 with a concave surface facing the object side in order from the object side. The plano-concave lens L20 is a glass mold aspherical lens with both surfaces made aspherical.

[0279] Next, a numerical embodiment in which specific numerical values ​​are applied to the zoom lens is described. Table 8 shows the surface data of the zoom lens. In Table 8, numbers 1 to 5 are the surface numbers of the first lens group G1. Numbers 6 to 13 are the surface numbers of the second lens group G2. Numbers 14 to 15 are the surface numbers of the third lens group G3. Numbers 16 to 29 are the surface numbers of the fourth lens group G4. Numbers 30 to 32 are the surface numbers of the fourth lens group G4. Numbers 33 to 38 are the surface numbers of the fourth lens group G4. Numbers 39 and 40 are the surface numbers of the protective glass CG.

[0280] [Table 7]

[0281]

[0282]

[0283]

[0284] Table 8 shows the elements of the zoom lens of Example 2.

[0285] [Table 8]

[0286] Wide-angle end middle Telephoto end f 72.0441 119.9950 174.6307 Fno 2.9098 2.9097 2.9108 ω 16.5054 9.7412 6.7336 Y 21.6330 21.6330 21.6330

[0287] Table 9 shows the distances of the variable intervals at an infinitely distant object. Table 10 shows the distances of the variable intervals at a photographic distance of 850 mm.

[0288] [Table 9]

[0289]

[0290]

[0291] [Table 10]

[0292] Wide-angle end middle 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

[0293] Table 11 is a table showing the focal lengths of the lens units constituting the zoom lens of Example 2.

[0294] [Table 11]

[0295] Group Number focal length G1 158.7770 G2 -140.1760 G3 -64.3774 G4 34.9860 G5 -38.7204 G6 234.6110

[0296] Table 12 shows the aspherical coefficients of the aspherical surfaces in the zoom lens of Example 2.

[0297] [Table 12]

[0298] serial number 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 serial number 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

[0299] [Example 3]

[0300] Fig. 9 : This is a diagram schematically showing the optical structure of the zoom lens of Example 3 at the wide-angle end when focusing at infinity. The zoom lens of Example 3 is composed of, from the object side, a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with negative optical power, a fourth lens group G4 with positive optical power, a fifth lens group G5 with positive optical power, a sixth lens group G6 with negative optical power, and a seventh lens group G7 with positive optical power. The first lens group G1, the second lens group G2, and the third lens group G3 are equivalent to the above-mentioned front group, and the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 are equivalent to the above-mentioned rear group. The first lens group G1 is equivalent to the above-mentioned lens group P. The second lens group G2 and the third lens group G3 are equivalent to the above-mentioned intermediate group M1. The third lens group G3 is equivalent to the above-mentioned lens group N. The fourth lens group G4 and the fifth lens group G5 are equivalent to the above-mentioned intermediate 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.

[0301] Fig. 9 The arrows in the figure indicate the direction and mode of movement of each lens group when zooming from the wide-angle end to the telephoto end. Fig. 9 As shown, when 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 plane side, the third lens group G3 gradually moves toward the image plane side, the fourth lens group G4 moves in a convex shape toward the image plane 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.

[0302] By moving the sixth lens group G6 toward the image plane, the zoom lens focuses from an object at infinity to an object at a close distance.

[0303] The aperture stop S is arranged adjacent to the object side of the fourth lens group G4.

[0304] The first lens group G1 is composed of, in order 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.

[0305] The second lens group G2 is composed of, in order from the object side, a biconvex lens L4, a concave lens L5 having a convex surface facing the object side, a biconcave lens L6, and a biconvex lens L7.

[0306] The third lens group G3 is composed of a negative meniscus lens L8 having a concave surface facing the object side.

[0307] The fourth lens group G4 is composed of 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 a convex surface facing the object side. The biconvex lens L9 is a glass molded aspheric lens with both surfaces set to an aspheric shape. Here, the cemented lens of the biconcave lens L13 and the positive meniscus lens L14 is equivalent to the above-mentioned anti-vibration group V.

[0308] 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.

[0309] The sixth lens group G6 is composed of a cemented lens of a biconvex lens L18 and a biconcave lens L19.

[0310] The seventh lens group G7 is composed of 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 in order from the object side. The negative meniscus lens L21 is a glass mold aspherical lens with both surfaces made aspherical.

[0311] In Table 13, numbers 1 to 5 are the surface numbers of the first lens group G1. Numbers 6 to 13 are the surface numbers of the second lens group G2. Numbers 14 to 15 are the surface numbers of the third lens group G3. Numbers 16 to 26 are the surface numbers of the fourth lens group G4. Numbers 27 to 31 are the surface numbers of the fifth lens group G5. Numbers 32 to 34 are the surface numbers of the sixth lens group G6. Numbers 35 to 40 are the surface numbers of the seventh lens group G7. Numbers 41 and 42 are the surface numbers of the protective glass CG.

[0312] [Table 13]

[0313]

[0314]

[0315]

[0316] Table 14 shows the elements of the zoom lens of Example 3.

[0317] [Table 14]

[0318] Wide-angle end middle Telephoto end f 72.0418 119.9846 174.6295 Fno 2.9098 2.9096 2.9105 ω 16.4071 9.8135 6.7152 Y 21.6330 21.6330 21.6330

[0319] Table 15 shows the distances of the variable intervals at an infinitely distant object. Table 16 shows the distances of the variable intervals at a photographic distance of 850 mm.

[0320] [Table 15]

[0321]

[0322]

[0323] [Table 16]

[0324] Wide-angle end middle 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

[0325] Table 17 is a table showing the focal lengths of the lens units constituting the zoom lens of Example 3.

[0326] [Table 17]

[0327]

[0328]

[0329] Table 18 shows the aspherical coefficients of the aspherical surface in the zoom lens of Example 3.

[0330] [Table 18]

[0331] serial number 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 serial number 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

[0332] [Example 4]

[0333] Fig.13 : This is a diagram schematically showing the optical structure of the zoom lens of Example 4 at the wide-angle end when focusing at infinity. The zoom lens of Example 4 is composed of, from the object side, a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with negative optical power, a fifth lens group G5 with positive optical power, and a sixth lens group G6 with negative optical power. The first lens group G1 and the second lens group G2 are equivalent to the above-mentioned front group, and the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 are equivalent to the above-mentioned rear group. The first lens group G1 is equivalent to the above-mentioned lens group P. The second lens group G2 is equivalent to the above-mentioned intermediate group M1. The second lens group G2 is equivalent to the above-mentioned lens group N. The third lens group G3 is equivalent to the above-mentioned intermediate group M2. The fourth lens group G4 is equivalent to the above-mentioned lens group F. The fifth lens group G5 and the sixth lens group G6 correspond to the rear group R described above.

[0334] Fig.13 The arrows in the figure indicate the direction and mode of movement of each lens group when zooming from the wide-angle end to the telephoto end. Fig.13 As shown, when 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 plane side, the third lens group G3 moves in a convex shape toward the image plane side, the fourth lens group G4 moves in a convex shape toward the image plane side, and the fifth lens group G5 gradually moves toward the image plane side. The sixth lens group G6 does not move.

[0335] By moving the fourth lens group G4 toward the image plane, the zoom lens focuses from an object at infinity to an object at a close distance.

[0336] The aperture stop S is arranged adjacent to the object side of the third lens group G3.

[0337] The first lens group G1 is composed of, in order 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.

[0338] The second lens group G2 is composed of, from the object side, a biconvex lens L4, a negative meniscus lens L5 with its convex surface facing the object side, a negative meniscus lens L6 with its convex surface facing the object side, a positive meniscus lens L7 with its convex surface facing the object side, and a negative meniscus lens L8 with its concave surface facing the object side.

[0339] The third lens group G3 is composed of 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 in order from the object side. Here, the cemented lens of the biconcave lens L12 and the positive meniscus lens L13 is equivalent to the above-mentioned anti-vibration group V. The biconvex lens L16 is a glass molded aspheric lens with both surfaces set to an aspheric shape.

[0340] The fourth lens group G4 is composed of a cemented lens of a biconvex lens L17 and a biconcave lens L18.

[0341] The fifth lens group G5 is composed of a biconvex lens L19. The biconvex lens L19 is a glass mold-cast aspheric lens having both surfaces formed into aspheric shapes.

[0342] The sixth lens group G6 is composed of a biconvex lens L20 and a negative meniscus lens L21 with a concave surface facing the object side in order from the object side. The negative meniscus lens L21 is a glass mold-type aspherical lens with both surfaces being aspherical.

[0343] In Table 19, numbers 1 to 5 are the surface numbers of the first lens group G1. Numbers 6 to 15 are the surface numbers of the second lens group G2. Numbers 16 to 29 are the surface numbers of the third lens group G3. Numbers 30 to 32 are the surface numbers of the fourth lens group G4. Numbers 33 to 34 are the surface numbers of the fifth lens group G5. Numbers 35 to 38 are the surface numbers of the sixth lens group G6. Numbers 39 and 40 are the surface numbers of the protective glass CG.

[0344] [Table 19]

[0345]

[0346]

[0347]

[0348] Table 20 shows the elements of the zoom lens of Example 4.

[0349] [Table 20]

[0350] Wide-angle end middle Telephoto end f 72.0452 120.0092 174.6309 Fno 2.9097 2.9103 2.9097 ω 16.4017 9.7407 6.7277 Y 21.6330 21.6330 21.6330

[0351] Table 21 shows the distances of the variable intervals at an infinitely distant object. Table 22 shows the distances of the variable intervals at a photographic distance of 850 mm.

[0352] [Table 21]

[0353] Wide-angle end middle 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

[0354] [Table 22]

[0355] Wide-angle end middle 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

[0356] Table 23 is a table showing the focal lengths of the lens units constituting the zoom lens of Example 4.

[0357] [Table 23]

[0358] Group Number focal length G1 155.8780 G2 -42.2798 G3 36.4842 G4 -54.1607 G5 150.0000 G6 -103.3940

[0359] Table 24 shows the aspherical coefficients of the aspherical surface in the zoom lens of Example 4.

[0360] [Table 24]

[0361]

[0362]

[0363] Table 25 shows the calculated values ​​based on the above-mentioned formulas in Examples 1 to 4 and the numerical values ​​used in the formulas.

[0364] [Table 25]

[0365]

[0366]

[0367] Table 26 shows the numerical values ​​used in the above formulas in Examples 1 to 4.

[0368] [Table 26]

[0369]

[0370]

Claims

1. A zoom lens having a plurality of lens groups, When the lens group disposed on the object side relative to the widest air gap between the lens groups at the wide-angle end is the front group, and the lens group disposed on the image plane side relative to the air gap is the rear group, The front group is composed of 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, in order from the object side, and has negative refractive power as a whole. The rear group is composed of, from the object side, an intermediate group M2 including one or more lens groups and having positive optical power as a whole, a lens group F having negative optical power as a whole, and a rear group R including one or more lens groups and having positive optical power as a whole. When zooming from wide angle to telephoto, The spacing between adjacent lens groups changes. The number of lens groups that are moved so as to change the intervals between adjacent lens groups is 5 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 middle group M1 is gradually moved toward the image plane side, and, At least one lens group having positive refractive power among the lens groups included in the intermediate group M2 moves along a trajectory that is convex toward the image plane. When focusing, the lens group F moves along the optical axis of the zoom lens. The zoom lens satisfies the following equation: 0.5≤bfw / Yw≤1.4···(1) 0.5≤fp / ft≤1.5···(2) -0.9≤fm1 / fw≤-0.15···(3) in, bfw: the back focal length of the optical system of the zoom lens at the wide-angle end Yw: Maximum image height at 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 middle group M1 at the wide-angle end fw: focal length of the optical system of the zoom lens at the wide-angle end.

2. The zoom lens according to claim 1, satisfying the following equation: 0.05≤Dm / Tw≤0.20···(4) Dm: The distance between the middle group M1 and the middle group M2 on the optical axis at the wide-angle end Tw: Total optical length at the wide-angle end.

3. The zoom lens according to claim 1, When the lens group having the largest negative refractive power among the lens groups having negative refractive power included in the middle group M1 is used as the lens group N, the following formula is satisfied: 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. The zoom lens according to claim 1, satisfying the following equation: 1.5≤|{1-(βft) 2 }×(βrt) 2 |≤9.5···(6) βft: lateral magnification of the 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.

5. The zoom lens according to claim 1, When zooming from the wide-angle end to the telephoto end, the lens group F moves along a locus that is convex toward the image plane.

6. The zoom lens according to claim 1, The intermediate group M2 comprises: The anti-vibration group V moves in a direction orthogonal to the optical axis and has a negative optical power.

7. The zoom lens according to claim 6, The intermediate group M2 includes one or more lenses on the object side and the image plane side of the anti-vibration group V, respectively. The lenses in the intermediate group M2 that are arranged closer to the object side than the anti-vibration group V have positive refractive power as a whole. The lenses in the middle group M2 that are arranged on the image plane side relative to the anti-vibration group V have positive refractive power as a whole.

8. The zoom lens according to claim 7, satisfying the following equation: 0.7≤fm2p / fm2≤2.0···(7) fm2p: The combined focal length of all the lenses in the intermediate group M2 arranged on the object side relative to the anti-vibration group V at the telephoto end fm2: The composite focal length of the middle group M2 at the telephoto end.

9. The zoom lens according to claim 7, satisfying the following equation: -3.3≤fm2v / fm2≤-1.2···(8) fm2v: focal length of the anti-vibration group V fm2: The composite focal length of the middle group M2 at the telephoto end.

10. The zoom lens according to claim 1, The lens group F includes at least one lens having positive refractive power and at least one lens having negative refractive power.

11. A camera device comprising: The zoom lens according to any one of claims 1 to 10; and The imaging element converts an optical image formed by the zoom lens into an electrical signal on the image plane side of the zoom lens.

Images