Zoom lens and imaging device

Abstract

To provide a compact zoom lens that offers high optical performance, and an image capturing device.SOLUTION: A zoom lens comprises, in order from the object side, a first lens group having negative refractive power, an intermediate group consisting of one or more lens groups and having positive refractive power as a whole, a lens group Ln having negative refractive power, and a final lens group having negative refractive power, and is configured such that distances between adjacent lens groups change while zooming or focusing, and that given conditional expressions are satisfied. An image capturing device equipped with such zoom lens is also provided herein.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a zoom lens and an imaging device, and more particularly to a zoom lens and an imaging device suitable for a small imaging device using a solid-state imaging device or the like.

[0002] In recent years, imaging devices using solid-state imaging devices such as digital still cameras and digital video cameras have become widespread. Along with this, the optical system has been improved in performance and miniaturized, and small imaging device systems have been rapidly spreading. However, it has been difficult to miniaturize the optical system while maintaining high optical performance for zoom lenses used in surveillance cameras, video cameras, digital still cameras, single-lens reflex cameras, mirrorless single-lens cameras, etc., which require a short and small optical system.

[0003] Therefore, Patent Document 1 proposes a zoom lens having a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens group having a negative refractive power in order from the object side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the zoom lens having the negative-positive-negative-negative refractive power arrangement of Patent Document 1, since the negative refractive power of the first lens group is weaker than the positive refractive power of the second lens group, it is necessary to arrange the lens with the largest lens diameter on the object side within the first lens group, and there is a problem that the miniaturization of the optical system in the radial direction is insufficient.

[0006] An object of the present invention is to provide a zoom lens and an imaging device that are smaller and have higher optical performance.

Means for Solving the Problem

[0007] As a result of intensive research to solve the above problems, the inventors have arrived at the following invention.

[0008] The zoom lens according to the present invention is composed of, in order from the object side, a first lens group having a negative refractive power, an intermediate group composed of one or more lens groups and having a positive refractive power as a whole, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power. The intermediate group includes a lens group LpMax. The lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group, and is a zoom lens that performs zooming or focusing by changing the interval between adjacent lens groups, and is characterized by satisfying the following conditional expression. 0.05 ≦ |f1| / |fpMax| ≦ 0.80 ···(1) However, f1: Focal length of the first lens group fpMax: Focal length of the lens group LpMax

[0009] The zoom lens according to the present invention is composed of, in order from the object side, a first lens group having a negative refractive power, an intermediate group composed of one or more lens groups and having a positive refractive power as a whole, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power. The intermediate group includes a lens group LpMax. The lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group, and is a zoom lens that performs zooming or focusing by changing the interval between adjacent lens groups, and is characterized by satisfying the following conditional expression. βpw ≦ -0.58 ···(2) However, βpw: Composite lateral magnification of the intermediate group at infinity focus at the wide-angle end

[0010] In order to solve the above problems, the imaging device according to the present invention is characterized by including the above-described zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal on the image side of the zoom lens.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a zoom lens and an imaging device that are smaller in size and have high optical performance over the entire zoom range.

Brief Description of the Drawings

[0012]

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Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments of the zoom lens and the imaging device according to the present invention will be described. However, the zoom lens and the imaging device described below are one aspect 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 aspects.

[0014] 1. Zoom Lens 1-1. Optical Configuration of Zoom Lens The zoom lens according to this embodiment includes, in order from the object side, a first lens group having a negative refractive power, an intermediate group composed of one or more lens groups and having a positive refractive power as a whole, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power. The intermediate group includes a lens group LpMax, and the lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group. And the zoom lens is configured to perform zooming or focusing by changing the distance between adjacent lens groups.

[0015] By arranging a negative refractive power in the first lens group and a positive refractive power in the intermediate group, the zoom lens has a light divergence effect on the object side and a light convergence effect on the image side. In this way, by adopting a so-called retrofocus configuration in the optical configuration of the zoom lens, the angle of view at the wide-angle end can be widened without increasing the size of the zoom lens. That is, the zoom lens has a power (refractive power) arrangement suitable for a wide-angle zoom lens.

[0016] Also, in order to shorten the overall optical length of the zoom lens according to this embodiment, it is preferable to adopt a so-called telephoto type refractive power arrangement. That is, it is preferable to arrange a lens group having a positive refractive power on the object side and a lens group having a negative refractive power on the image side. In the zoom lens, on the image side of the first lens group, in order from the object side, there are provided an intermediate group having a positive refractive power as a whole, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power. By adopting such a refractive power arrangement, the power arrangement on the image side of the first lens group can be made more telephoto-like. That is, the zoom lens can shorten the length on the optical axis from the intermediate group to the final lens group compared to the combined focal length from the intermediate group to the final lens group, and can shorten the overall optical length of the zoom lens.

[0017] Hereinafter, the optical configuration and the like of each lens group will be described.

[0018] (1) First lens group As described above, the first lens group is arranged closest to the object side among the plurality of lens groups constituting the zoom lens. As long as it has a negative refractive power, its specific lens configuration is not particularly limited. Further, the first lens group preferably has a lens L1p having a positive refractive power on the most image side within the group. This is because if this lens L1p or the lens surface on its image side satisfies a predetermined conditional expression described later, the lens diameter of the lens arranged closest to the object side within the group can be made smaller.

[0019] (2) Intermediate group The intermediate group is arranged on the image side of the first lens group described above. As long as it is composed of one or more lens groups and has a positive refractive power as a whole, its specific lens group and the configuration of the lenses within each group are not particularly limited. The intermediate group only needs to include at least one lens group having a positive refractive power within the group. It may have two or more lens groups having a positive refractive power, or may have one or more lens groups having a positive refractive power and one or more lens groups having a negative refractive power respectively. In the present invention, the lens group having the strongest positive refractive power among the lens groups included in the intermediate group is referred to as the lens group LpMax.

[0020] (3) Lens group Ln The lens group Ln is arranged on the image side of the intermediate group described above. As long as it has a negative refractive power, its specific lens configuration is not particularly limited. Further, it is preferable for the lens group Ln to be a single lens having a negative refractive power in terms of operating the operation of the lens group Ln at high speed. And it is preferable for the lens arranged on the most image side within the group to be a meniscus lens in terms of correcting field curvature.

[0021] (4) Final lens group The final lens group is arranged on the most image side among the plurality of lens groups constituting the zoom lens. As long as it has a negative refractive power, its specific lens configuration is not particularly limited. Further, it is preferable for the final lens group to be two lenses, namely a lens having a positive refractive power and a lens having a negative refractive power in order from the object side, in terms of miniaturizing the optical system.

[0022] (5) Focus group In the zoom lens, the presence or absence of a focus group is not particularly limited. When a focus group is provided in the zoom lens, at least one of the lenses constituting the lens is used as the focus group, and when focusing, the focus group can be moved in the optical axis direction to focus on the subject. In the zoom lens, the position and refractive power of the lens used as the focus group are not particularly limited.

[0023] (6) Vibration-proof group In the zoom lens, the presence or absence of a vibration-proof group is not particularly limited. When a vibration-proof group is provided in the zoom lens, at least one of the lenses constituting the zoom lens is used as the vibration-proof group, and when the vibration-proof group is moved in a direction substantially orthogonal to the optical axis to perform image shift (so-called shake correction), the entire zoom lens unit including the lens barrel can be downsized, which is preferable for downsizing the optical system. Note that the zoom lens unit includes, in addition to the zoom lens, a drive mechanism (zoom drive mechanism) for relatively moving each lens group during zooming, a drive mechanism (focus drive mechanism) for moving the focus group in the optical axis direction during focusing, and a lens barrel for housing these.

[0024] (7) Aperture stop In the zoom lens, the position of the aperture stop is not particularly limited. However, the aperture stop here refers to the aperture stop that defines the light beam diameter of the zoom lens, that is, the aperture stop that defines the F-number of the zoom lens.

[0025] In the zoom lens, it is preferable to arrange the aperture stop on the image side of the first lens group for downsizing the aperture unit, and it is more preferable to arrange it in the intermediate group for further downsizing.

[0026] (8) Lens group configuration The number of lens groups constituting the zoom lens is not particularly limited. For example, a zoom lens having a five-group configuration including a first lens group having a negative refractive power, an intermediate group composed of a second lens group having a positive refractive power and a third lens group having a positive refractive power, a lens group Ln composed of a fourth lens group having a negative refractive power, and a final lens group composed of a fifth lens group having a negative refractive power; a zoom lens having a six-group configuration including a first lens group having a negative refractive power, an intermediate group composed of a second lens group having a positive refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power and having a positive refractive power as a whole, a lens group Ln composed of a fifth lens group having a negative refractive power, and a final lens group composed of a sixth lens group having a negative refractive power. Various configurations of lens groups can be adopted. That is, as long as the configuration includes, in order from the object side, a first lens group having a negative refractive power, an intermediate group having a positive refractive power, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power, the specific lens group configuration of the zoom lens is not particularly limited.

[0027] 1-2. Operation (1) Operation during zooming When the zoom lens zooms from the wide-angle end to the telephoto end, the interval between adjacent lens groups changes.

[0028] When the zoom lens zooms from the wide-angle end to the telephoto end, it is only necessary that the air interval between adjacent lens groups changes, and the increase or decrease of the air interval of each lens group is not particularly limited. Also, when zooming, all the lens groups constituting the zoom lens may be moved in the optical axis direction, or some of the lens groups may be fixed in the optical axis direction and the remaining lens groups may be moved in the optical axis direction. The presence or absence of movement and the direction of movement of each individual lens group are not particularly limited.

[0029] (2) Operation during focusing When a focus group is provided in the zoom lens, the position, refractive power, moving direction, etc. of the focus group are not particularly limited. However, when using the lens group Ln as the focus group and focusing from infinity to a nearby object, it is preferable to move the lens group Ln toward the image side for focusing. The lens group Ln is arranged on the image side of the intermediate group, and since the variation in the light incident angle is small, the variation in the angle of view during focusing can be suppressed.

[0030] 1-3. Conditional expression The zoom lens of the present invention preferably adopts the above-described configuration and satisfies either conditional expression (1) or conditional expression (2) described below.

[0031] 1-3-1. Conditional expression (1) 0.05 ≦ |f1| / |fpMax| ≦ 0.80 ···(1) However, f1: Focal length of the first lens group fpMax: Focal length of the lens group LpMax

[0032] The above conditional expression (1) is an expression for defining the ratio between the focal length of the first lens group and the focal length of the lens group LpMax having the strongest positive refractive power among the lens groups included in the intermediate group. By satisfying conditional expression (1), the angle of view can be widened at the wide-angle end, and the aberration variation during zooming can be suppressed. That is, by satisfying the above conditional expression (1), a zoom lens with a wide angle of view at the wide-angle end and high optical performance can be realized.

[0033] On the other hand, if the value of the conditional expression (1) is less than the lower limit value, the power of the first lens group becomes too strong relative to the power of the intermediate group, making it difficult to correct coma aberration and distortion aberration, and it becomes difficult to realize a zoom lens with high optical performance, which is not preferable. On the contrary, if the value of the conditional expression (1) exceeds the upper limit value, the power of the first lens group becomes too weak relative to the power of the intermediate group, which is not preferable. That is, in order to achieve a wide-angle effect at the wide-angle end, it is necessary to arrange the lens with the largest lens diameter on the object side among the lenses constituting the first lens group, and it becomes difficult to achieve miniaturization in the radial direction, which is not preferable.

[0034] In order to obtain these effects, the lower limit value of the conditional expression (1) is more preferably 0.10, further preferably 0.15, and still more preferably 0.20. Also, the upper limit value of the conditional expression (1) is more preferably 0.75, further preferably 0.70, and still more preferably 0.65.

[0035] 1-3-2. Conditional Expression (2) βpw ≦ -0.58 ···(2) However, βpw: The combined lateral magnification of the intermediate group at infinity focus at the wide-angle end

[0036] The above conditional expression (2) is an equation for defining the combined lateral magnification of the intermediate group at infinity focus at the wide-angle end. By satisfying the conditional expression (2), the power of the first lens group can be strengthened, and the angle of view can be widened while miniaturizing the first lens group in the radial direction at the wide-angle end. Therefore, the aberration variation during zooming can be suppressed. That is, a zoom lens with a wide angle of view, small size, and high optical performance can be realized.

[0037] On the other hand, if the value of the conditional expression (2) exceeds the upper limit value, the power of the first lens group cannot be increased. To achieve a wider angle of view at the wide-angle end, it is necessary to arrange the lens with the largest lens diameter among the lenses constituting the first lens group on the object side, making it difficult to achieve miniaturization in the radial direction, which is not preferable.

[0038] To obtain these effects, the upper limit value of the conditional expression (2) is more preferably -0.60, even more preferably -0.62, still more preferably -0.64, and yet more preferably -0.66.

[0039] The zoom lens of the present invention preferably satisfies either the above-described conditional expression (1) or conditional expression (2), and at least one of the following conditional expressions.

[0040] 1-3-3. Conditional Expression (3) -1.50 ≦ f1 / fw ≦ -0.05 ···(3) However, f1: Focal length of the first lens group fw: Focal length of the zoom lens at infinity focus at the wide-angle end

[0041] The above conditional expression (3) is an expression for defining the focal length of the first lens group. By satisfying the conditional expression (3), the angle of view can be widened at the wide-angle end, and the aberration variation during zooming can be suppressed. That is, a zoom lens with a wide angle of view at the wide-angle end and high optical performance can be realized.

[0042] On the other hand, if the value of the conditional expression (3) is less than the lower limit value, to achieve a wider angle of view at the wide-angle end, it is necessary to arrange the lens with the largest lens diameter among the lenses constituting the first lens group on the object side, making it difficult to achieve miniaturization in the radial direction. On the other hand, if the value of the conditional expression (3) exceeds the upper limit value, the power of the first lens group becomes too strong, making it difficult to correct coma aberration and distortion aberration, and it becomes difficult to realize a zoom lens with high optical performance.

[0043] In order to obtain these effects, the lower limit value of conditional expression (3) is more preferably -1.45, even more preferably -1.40, still more preferably -1.35, yet more preferably -1.30, and even yet more preferably -1.25. Further, the upper limit value of conditional expression (3) is more preferably -0.10, even more preferably -0.15, and still more preferably -0.20.

[0044] 1-3-4. Conditional Expression (4) -4.0 ≦ fn / fpMax ≦ -1.5 ···(4) However, fn: Focal length of lens group Ln fpMax: Focal length of lens group LpMax

[0045] The above conditional expression (4) is an expression for defining the ratio between the focal length of lens group Ln and the focal length of lens group LpMax. By satisfying conditional expression (4), high telephoto conversion of the optical system (the optical system composed of the intermediate group, lens group Ln, and the final lens group) on the image side with respect to the first lens group becomes possible, and shortening of the overall optical length can be realized.

[0046] On the other hand, when the numerical value of conditional expression (4) is less than the lower limit value, the power of lens group Ln becomes too strong, making it difficult to correct distortion aberration and coma aberration, which is not preferable. Also, when the power of lens group Ln becomes too strong, the height of peripheral rays passing through the final lens group arranged on the image side with respect to lens group Ln increases, and it becomes necessary to arrange a lens with the largest lens diameter on the most image side of the final lens group, making it difficult to achieve miniaturization in the radial direction, which is not preferable. On the other hand, when the numerical value of conditional expression (4) exceeds the upper limit value, the overall length of the optical system becomes long, and miniaturization of the zoom lens cannot be achieved, which is not preferable.

[0047] In order to obtain these effects, the lower limit value of conditional expression (4) is more preferably -3.9, even more preferably -3.8, still more preferably -3.7, and yet more preferably -3.6. Also, the upper limit value of conditional expression (4) is more preferably -1.6, even more preferably -1.7, and still more preferably -1.8.

[0048] 1-3-5. Conditional expression (5) 0.05 ≦ frt / ft ≦ 1.50 ···(5) However, frt: The combined focal length from the intermediate lens group to the final lens group at infinity focus at the telephoto end ft: The focal length of the zoom lens at infinity focus at the telephoto end

[0049] The above conditional expression (5) is an equation for defining the combined focal length from the intermediate lens group to the final lens group at infinity focus at the telephoto end. By satisfying conditional expression (5), it is possible to achieve both miniaturization of the zoom lens and high optical performance.

[0050] On the other hand, if the numerical value of conditional expression (5) is less than the lower limit value, it is not preferable because it becomes difficult to correct distortion aberration, coma aberration, and spherical aberration. On the other hand, if the numerical value of conditional expression (5) exceeds the upper limit value, it is necessary to increase the aperture of the most object-side lens in the first lens group, and it is not possible to miniaturize the zoom lens, which is not preferable.

[0051] In order to obtain these effects, the lower limit value of conditional expression (5) is more preferably 0.10, even more preferably 0.15, and still more preferably 0.20. Also, the upper limit value of conditional expression (5) is more preferably 1.45, even more preferably 1.40, and still more preferably 1.35.

[0052] 1-3-6. Conditional expression (6) 1.00≦ βn1≦5.00 ·····(6) However, βn1: Lateral magnification of the lens group Ln at infinity focus at the wide-angle end

[0053] The above conditional expression (6) is an expression for defining the lateral magnification of the lens group Ln at infinity focus at the wide-angle end. By satisfying the conditional expression (6), it is possible to achieve high performance of the optical performance throughout the zoom range and to shorten the overall optical length.

[0054] On the other hand, when the numerical value of the conditional expression (6) is less than the lower limit value, the movement amount of the lens group Ln during zooming from the wide-angle end to the telephoto end becomes too large, so the overall length of the optical system becomes long, and it is not possible to achieve miniaturization of the zoom lens, which is not preferable. On the other hand, when the numerical value of the conditional expression (6) exceeds the upper limit value, the lateral magnification of the lens group Ln becomes too high, so it becomes difficult to correct distortion aberration and field curvature, which is not preferable.

[0055] In order to obtain these effects, the lower limit value of the conditional expression (6) is more preferably 1.10, further preferably 1.20, and still more preferably 1.30. Also, the upper limit value of the conditional expression (6) is more preferably 4.90, further preferably 4.80, and still more preferably 4.70.

[0056] 1-3-7. Conditional expression (7) 1.00 ≦ βn12 ≦ 5.00 ···(7) However, βn12: Composite lateral magnification of the lens group Ln and the final lens group at infinity focus at the wide-angle end

[0057] The above conditional expression (7) is an expression for defining the composite lateral magnification of the lens group Ln and the final lens group at infinity focus at the wide-angle end. By satisfying the conditional expression (7), it is possible to achieve high performance of the optical performance throughout the zoom range and to shorten the overall optical length.

[0058] On the other hand, when the numerical value of the conditional expression (7) is less than the lower limit value, the moving amounts of the lens group Ln and the final lens group during zooming from the wide-angle end to the telephoto end become too large, so the overall length of the optical system becomes long, and it is not possible to miniaturize the zoom lens, which is not preferable. On the other hand, when the numerical value of the conditional expression (7) exceeds the upper limit value, the combined lateral magnification of the lens group Ln and the final lens group becomes too high, making it difficult to correct distortion and field curvature, which is not preferable.

[0059] In order to obtain these effects, it is more preferable that the lower limit value of the conditional expression (7) is 1.10, further preferably 1.20, and still more preferably 1.30. Also, it is more preferable that the upper limit value of the conditional expression (7) is 4.90, further preferably 4.80, and still more preferably 4.70.

[0060] 1-3-8. Conditional Expression (8) When focusing from infinity to a close object by moving the lens group Ln in the optical axis direction, it is preferable to satisfy the following conditional expression. 0.60 ≦ |{1-(βn1×βn1)}×(βn2×βn2)| ≦ 15.0 ···(8) However, βn1: Lateral magnification of the lens group Ln at infinity focus at the wide-angle end βn2: Lateral magnification of the final lens group at infinity focus at the wide-angle end

[0061] The above conditional expression (8) is an expression for defining the absolute value of the focus sensitivity of the lens group Ln that moves on the optical axis during focusing, that is, the amount of image plane movement when the lens group Ln moves by a unit amount. By satisfying the conditional expression (8), it is possible to shorten the moving amount of the focus group (lens group Ln) during focusing from infinity to the closest distance (close object), and a zoom lens with a short overall optical length can be realized.

[0062] On the other hand, if the value of the conditional expression (8) is less than the lower limit value, the moving amount of the lens group Ln when focusing from an infinite object to a close object increases, making it difficult to reduce the overall optical length, which is not preferable. On the contrary, if the value of the conditional expression (8) exceeds the upper limit value, the moving amount of the lens group Ln for correcting the deviation of the focus position becomes too small, requiring high-precision control, which is not preferable.

[0063] To obtain these effects, the lower limit value of the conditional expression (8) is more preferably 0.65, and even more preferably 0.70. Also, the upper limit value of the conditional expression (8) is more preferably 14.0, even more preferably 13.0, and still more preferably 12.0.

[0064] 1-3-9. Conditional Expression (9) 1.00 ≦ |CrG1r / fw| ···(9) However, CrG1r: Radius of curvature of the most image-side lens surface in the first lens group fw: Focal length of the zoom lens at infinity focus at the wide-angle end

[0065] The above conditional expression (9) is an equation for defining the radius of curvature of the most image-side lens surface in the first lens group. By satisfying the conditional expression (9), it is easy to correct spherical aberration and field curvature, and it is possible to achieve miniaturization while realizing high performance.

[0066] On the other hand, if the value of the conditional expression (9) is less than the lower limit value, the field curvature becomes overcorrected, and it becomes necessary to increase the aperture of the most object-side lens in the first lens group, making it impossible to reduce the size of the zoom lens, which is not preferable.

[0067] To obtain these effects, the lower limit value of the conditional expression (9) is more preferably 1.50, even more preferably 2.00, still more preferably 2.50, even still more preferably 3.00, and even more preferably 3.50.

[0068] 1-3-10. Conditional expression (10) 0.65 ≦ (fw×tanω) / BFw ≦ 2.30 ···(10) However,[[]] fw: Focal length of the zoom lens at infinity focus at the wide-angle end ω: Half angle of view of the zoom lens at infinity focus at the wide-angle end BFw: Distance on the optical axis between the most image-side lens surface and the image plane of the zoom lens at infinity focus at the wide-angle end

[0069] The above conditional expression (10) is an expression for defining the ratio between the angle of view at the wide-angle end and the distance between the most image-side lens surface and the image plane (optical system back focus) of the zoom lens at the wide-angle end. By satisfying the conditional expression (10), high performance of the optical performance across the entire zoom range can be achieved, and shortening of the overall optical length can be achieved.

[0070] When the value of the conditional expression (10) is less than the lower limit, it is not preferable because it is necessary to increase the incident angle of off-axis rays to the image plane. That is, it becomes necessary to reduce the focal length of the final lens group, making it difficult to correct coma aberration and distortion aberration, which is not preferable. Or, it becomes necessary to increase the lens diameter of the final lens group, making it impossible to miniaturize the zoom lens, which is not preferable. When the value of the conditional expression (10) exceeds the upper limit, the overall length of the optical system becomes long, making it impossible to miniaturize the zoom lens, which is not preferable.

[0071] In order to obtain these effects, it is more preferable that the lower limit value of the conditional expression (10) is 0.70, further preferably 0.75, still more preferably 0.80, even more preferably 0.85, and even further preferably 0.90. Also, it is more preferable that the upper limit value of the conditional expression (10) is 2.20, further preferably 2.10, still more preferably 2.00, even more preferably 1.90, and even further preferably 1.80.

[0072] 1-3-11. Conditional expression (11) The zoom lens of the present invention has at least one lens LpMp having a positive refractive power in the lens group LpMax, and preferably satisfies the following conditional expression. 45.0 ≦ νdLpMp ≦ 98.0 ···(11) However, νdLpMp: Abbe number of the lens LpMp at the d line

[0073] The above conditional expression (11) is an expression for defining the Abbe number at the d line of the lens LpMp included in the lens group LpMax. By satisfying the conditional expression (11), it is easy to correct the axial chromatic aberration and the spherical aberration, and it is possible to miniaturize while realizing high performance.

[0074] When the numerical value of the conditional expression (11) is less than the lower limit value, it is not preferable because it becomes difficult to correct the axial chromatic aberration. When the numerical value of the conditional expression (11) exceeds the upper limit, the lens becomes expensive, which is not preferable in terms of cost reduction.

[0075] In order to obtain these effects, the lower limit value of the conditional expression (11) is more preferably 50.0, further preferably 55.0, and still more preferably 60.0. Also, the upper limit value of the conditional expression (11) is more preferably 95.0, further preferably 90.0, and still more preferably 85.0.

[0076] 1-3-12. Conditional expression (12) The zoom lens of the present invention has at least one lens L1p having a positive refractive power in the first lens group, and preferably satisfies the following conditional expression. 20.0 ≦ νdL1p ≦ 50.0 ···(12) However, νdL1p: Abbe number of the lens L1p at the d line

[0077] The above conditional expression (12) is an expression for defining the Abbe number of the lens L1p having a positive refractive power included in the first lens group. In a lens group having a negative refractive power, it is common to correct the chromatic aberration of magnification by using a high-dispersion glass for the lens having a positive refractive power and a low-dispersion glass for the lens having a negative refractive power. However, since a high-dispersion glass with a numerical value of the above conditional expression (12) less than the lower limit value is expensive, it is not preferable in terms of cost reduction. Also, when the numerical value of the above conditional expression (12) exceeds the upper limit, it is not preferable because it becomes difficult to correct the chromatic aberration of magnification even if a low-dispersion glass is used for the lens having a negative refractive power. That is, by satisfying the conditional expression (12) with the structure of the zoom lens, it is possible to achieve cost reduction while ensuring good image plane properties.

[0078] In obtaining these effects, it is more preferable that the lower limit value of the conditional expression (12) is 22.0, further preferably 24.0, and still more preferably 26.0. Also, it is more preferable that the upper limit value of the conditional expression (12) is 47.0, further preferably 44.0, and still more preferably 41.0.

[0079] 1-3-13. Conditional Expression (13) The zoom lens of the present invention has at least one lens L1p having a positive refractive power in the first lens group, and preferably satisfies the following conditional expression. 1.70 ≦ NdL1p ≦ 2.20 ···(13) However, NdL1p: Refractive index of the lens L1p at the d line

[0080] The above conditional expression (13) is an expression for defining the refractive index of the lens L1p having a positive refractive power included in the first lens group at the d-line. In a lens group having a negative refractive power, it is common to correct the Petzval sum by using a high refractive index glass for the lens having a positive refractive power and a low refractive index glass for the lens having a negative refractive power. Here, if the numerical value of the above conditional expression (13) is less than the lower limit value, it is not preferable because it becomes difficult to correct the image plane property. Further, a high refractive index glass having a refractive index such that the numerical value of the conditional expression (13) exceeds the upper limit is expensive, so it is not preferable in terms of cost reduction. That is, by satisfying the conditional expression (13), it is possible to achieve cost reduction while ensuring good image plane property.

[0081] In obtaining these effects, the lower limit value of the conditional expression (13) is more preferably 1.75, further preferably 1.80, and still more preferably 1.85. Also, the upper limit value of the conditional expression (13) is more preferably 2.15, further preferably 2.10, and still more preferably 2.05.

[0082] 1-3-14. Conditional Expression (14) |BFt - BFw| / TLw ≤ 0.30 ···(14) However, BFt: The distance on the optical axis between the most image-side lens surface of the zoom lens and the image plane at infinity focus at the telephoto end BFw: The distance on the optical axis between the most image-side lens surface of the zoom lens and the image plane at infinity focus at the wide-angle end TLw: The overall optical length of the zoom lens at infinity focus at the wide-angle end

[0083] The above conditional expression (14) is an expression for defining the amount of movement of the final lens group toward the object side when zooming from the wide-angle end to the telephoto end. By satisfying the conditional expression (14), the refractive power of the final lens group is appropriate, and the amount of movement during zooming is within an appropriate range. Therefore, while ensuring a predetermined zoom ratio, it is possible to shorten the overall optical length at the telephoto end.

[0084] On the other hand, when the numerical value of the conditional expression (14) exceeds the upper limit value, the above-described moving amount of the final lens group during zooming (the moving amount of the final lens group toward the object side when zooming from the wide-angle end to the telephoto end) increases. In this case, when the lens barrel has a nested structure in which the inner barrel portion is housed in the outer barrel portion, if the lens barrel length is designed in accordance with the overall optical length at the wide-angle end, the structure of the lens barrel becomes complicated, such as the need to double the inner barrel portion and house it in the outer barrel portion, and the outer diameter of the lens barrel also increases (the product becomes larger), which is not preferable.

[0085] In order to obtain these effects, the upper limit value of the conditional expression (14) is more preferably 0.27, further preferably 0.24, still more preferably 0.21, and even more preferably 0.18.

[0086] 2. Imaging Device Next, the imaging device according to the present invention will be described. The imaging device according to the present invention is characterized by including the zoom lens according to the present invention described above, and an imaging element that converts the optical image formed by the zoom lens into an electrical signal on the image side of the zoom lens.

[0087] Here, there is no particular limitation on the imaging element or the like, and solid-state imaging elements such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The imaging device according to the present invention is suitable for imaging devices using these solid-state imaging elements such as digital cameras and video cameras. Further, the imaging device may be a lens-fixed imaging device in which the lens is fixed to the housing, or of course, may be an interchangeable-lens imaging device such as a single-lens reflex camera or a mirrorless single-lens camera.

[0088] When the imaging device preferably has an image processing unit that electrically processes the captured image data acquired by the image sensor to change the shape of the captured image, an image correction data holding unit that holds image correction data, an image correction program, etc. used for processing the captured image data in the image processing unit, and the like. When the zoom lens is miniaturized, distortion (aberration) is likely to occur in the shape of the captured image formed on the imaging surface. At this time, it is preferable to previously hold distortion correction data for correcting the distortion of the captured image shape in the image correction data holding unit, and in the above-described image processing unit, use the distortion correction data held in the image correction data holding unit to correct the distortion of the captured image shape. With such an imaging device, since the negative refractive power of the lens disposed closest to the image side within the zoom lens can be increased, the diameter of the lens disposed closest to the image side of the zoom lens can be miniaturized. That is, according to the imaging device, further miniaturization of the zoom lens can be achieved, a beautiful captured image can be obtained, and the entire imaging device can be miniaturized.

[0089] Next, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples.

Examples

[0090] (1) Optical configuration of the zoom lens FIG. 1 is a cross-sectional view showing the lens configuration at infinity focus at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 1 of the present invention. Note that “IP” shown in FIG. 1 is the imaging surface (image plane), specifically, the imaging surface of a solid-state image sensor such as a CCD sensor or a CMOS sensor, or the film surface of a silver halide film, etc. Further, on the object side of the imaging surface IP, a parallel plate having substantially no refractive power such as a cover glass “CG” is provided. Since these points are the same in each lens cross-sectional view shown in other embodiments, the description will be omitted below.

[0091] The zoom lens of Example 1 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a negative refractive power. The aperture stop S is disposed adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2 and the third lens group G3, and the lens group Ln corresponds to the fourth lens group G4.

[0092] Hereinafter, the configurations of the respective lens groups will be described. The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L101 with a convex object side, a negative meniscus lens L102 with a convex object side, a biconcave lens L103, and a positive meniscus lens L104 with a convex object side. Incidentally, each lens surface on the image side of the lens L102 and the lens L104 is a so-called compound aspherical surface in which an aspherical film is attached to the glass surface. Further, the lens L104 corresponds to the lens "L1p" in the present invention, and the lens surface on the image side of the lens L104 corresponds to the lens surface "CrG1r" in the present invention.

[0093] The second lens group G2 is composed of a cemented lens in which a negative meniscus lens L105 with a convex object side and a biconvex lens L106 are cemented together.

[0094] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a cemented lens in which a biconvex lens L107 and a biconcave lens L108 are cemented together, a cemented lens in which a negative meniscus lens L109 with a convex object side and a positive meniscus lens L110 with a convex object side are cemented together, and a biconvex lens L111. Incidentally, both surfaces of the lens L111 are aspherical surfaces. Further, the third lens group G3 corresponds to the lens group "LpMax" in the present invention, and the lens L111 corresponds to the lens "LpMp" in the present invention.

[0095] The fourth lens group G4 is composed of a negative meniscus lens L112 with a convex object side.

[0096] The fifth lens group G5 is composed of a biconvex lens L113 and a biconcave lens L114 in order from the object side. Both surfaces of the lens L113 are aspherical.

[0097] In the zoom lens of Example 1, when zooming from the wide-angle end to the telephoto end, after the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, the second lens group G2 moves toward the object side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side.

[0098] Also, when focusing from an infinite object to a close object, the fourth lens group G4 moves from the object side toward the image side along the optical axis in the zoom lens.

[0099] In the zoom lens, by using the lens L111 included in the third lens group G3 as an anti-shake group and moving the anti-shake group in a direction perpendicular to the optical axis, shake correction can be performed.

[0100] (2) Numerical Examples Next, numerical examples applying the specific numerical values of the zoom lens will be described. In the following tables, the unit of length is all "mm", and the unit of the angle of view is all "°". Table 1 shows the surface data of the zoom lens. In Table 1, "surface number" is the order of the lens surfaces counted from the object side, "R" is the radius of curvature of the lens surface, "D" is the interval on the optical axis of the lens surface, "Nd" is the refractive index with respect to the d-line (wavelength λ = 587.6 nm), and "ABV" is the Abbe number with respect to the d-line. Also, "ASP" displayed in the column next to the surface number indicates that the lens surface is aspherical, and "S" represents the aperture stop. Further, in the column of the interval on the optical axis of the lens surface, the notations such as "D(10)", "D(13)" mean that the interval on the optical axis of the lens surface is a variable interval that changes during zooming or focusing. Also, "∞ (infinity)" of the radius of curvature means a plane. The 29th and 30th surfaces in Table 1 are the surface data of the cover glass (CG).

[0101] Table 2 is the origin table of the zoom lens. The origin table shows the focal length "f", F-number "Fno.", half field angle "ω", image height "Y", overall optical length "TL" of the zoom lens at infinity focus, and the variable intervals on the optical axis of the zoom lens during zooming and focusing. However, Table 2 shows the respective values at the wide-angle end, intermediate focal length state, and telephoto end in order from the left.

[0102] Table 3 shows the surface numbers of the lenses included in each lens group constituting the zoom lens and the focal lengths of each lens group.

[0103] Table 4 shows the aspherical coefficients of each aspherical surface. The aspherical coefficients are the values when each aspherical shape is defined by the following formula.

[0104] X(Y)=CY 2 / [1+{1-(1+Κ)·C 2 Y 2} 1 / 2 +A4·Y 4 +A6·Y 6 +A8·Y 8 +A 10 ·Y 10

[0105] However, in Table 4, "E-a" indicates "×10 -a ". Also, in the above formula, "X" is the displacement amount from the reference plane in the optical axis direction, "C" is the curvature at the surface vertex, "Y" is the height from the optical axis in the direction perpendicular to the optical axis, "Κ" is the conic coefficient, and "A n " is the aspherical coefficient of the nth order.

[0106] Also, Table 21 shows the values of conditional expressions (1) to (14) and the respective values used in the calculations of conditional expressions (1) to (14).

[0107] Since the matters related to the above-described tables are the same in the respective tables shown in other embodiments, the description will be omitted below.

[0108] [Table 1] Surface number R D Nd ABV Object plane ∞ ∞ 1 51.4464 2.0000 1.89085 36.41 2 20.0000 5.7196 3 47.2371 1.5000 1.72916 54.67 4 23.5686 0.2000 1.53610 41.21 5 ASP 19.7552 6.4678 6 -206.9428 1.5000 1.72916 54.67 7 23.0858 1.9587 8 26.8465 4.0557 1.85764 22.33 9 121.5647 0.2000 1.53610 41.21 10 ASP 105.4586 D(10) 11 29.2922 1.0000 1.92108 22.20 12 16.8467 4.9210 1.64109 33.36 13 -216.9562 D(13) 14 S ∞ 2.0000 15 59.2608 4.0417 1.54697 68.55 16 -17.6603 1.0000 1.71375 55.52 17 69.4793 0.1016 18 20.2723 1.0000 1.80899 42.96 19 13.2943 3.8193 1.51650 70.18 20 51.7432 4.1444 21 ASP 34.3114 6.1621 1.48556 80.01 22 ASP -18.9780 D(22) 23 32.3936 1.0000 1.68811 57.08 24 19.0779 D(24) 25 ASP 23.9793 8.9358 1.49700 81.61 26 ASP -18.9694 0.1000 27 -34.6849 1.2000 1.73979 49.98 28 22.9171 D(28) 29 ∞ 2.5000 1.51680 64.20 30 ∞ 1.0000

[0109] [Table 2] Wide-angle end Intermediate focal length Telephoto end f 15.45 21.84 29.11 Fno. 2.88 3.60 4.12 ω 56.70 45.52 36.98 Y 19.97 20.64 21.23 TL 120.00 117.10 119.65 D(10) 10.1655 5.7974 3.1563 D(13) 16.3597 7.5636 2.1111 D(22) 6.1150 3.5611 2.4945 D(24) 3.4600 6.0138 7.0805 D(28) 17.3722 27.6314 38.2786

[0110] [Table 3] Group Surface number Focal length G1 1-10 -16.25 G2 11-13 55.96 G3 14-22 28.71 G4 23-24 -69.58 G5 25-28 -400.00

[0111] [Table 4] Surface number K A4 A6 A8 A10 5 0.00000E+00 -2.23462E-05 -4.09357E-08 -8.91357E-11 0.00000E+00 10 0.00000E+00 4.48229E-06 6.87070E-09 -5.54223E-11 0.00000E+00 21 0.00000E+00 -2.17920E-05 -5.42256E-09 1.86040E-10 0.00000E+00 22 0.00000E+00 3.69697E-05 -7.19257E-08 2.55987E-10 0.00000E+00 25 0.00000E+00 1.97160E-05 -5.15489E-08 3.03503E-10 -5.84468E-13 26 0.00000E+00 5.13298E-05 -3.64861E-08 2.43868E-10 -2.67122E-13

[0112] Figures 2 to 4 respectively show the longitudinal aberration diagrams at the wide-angle end, intermediate focal length state, and telephoto end of the zoom lens of Example 1 when focused at infinity. The longitudinal aberration diagrams shown in each figure are, in order from the left side towards the drawing surface, spherical aberration (mm), astigmatism (mm), and distortion (%) respectively. In the figure representing spherical aberration, the vertical axis is the ratio to the open F value, the horizontal axis takes defocus, the solid line represents the spherical aberration at the d line (wavelength λ = 587.6 nm), the dashed line represents the spherical aberration at the F line (wavelength λ = 486.1 nm), and the dotted line represents the spherical aberration at the C line (wavelength λ = 656.3 nm). In the figure representing astigmatism, the vertical axis is the semi-field angle, the horizontal axis takes defocus, the dash-dotted line represents the sagittal image plane (S) with respect to the d line, and the solid line represents the meridional image plane (M) with respect to the d line. In the figure representing distortion, the vertical axis is the semi-field angle, the horizontal axis takes %, and represents the distortion. Matters regarding these longitudinal aberration diagrams are the same as those in the longitudinal aberration diagrams shown in other embodiments, so the description will be omitted below.

Example

[0113] (1) Optical configuration of the zoom lens FIG. 5 is a cross-sectional view showing the lens configurations at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 2 of the present invention when focused at infinity. The zoom lens includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a negative refractive power. The aperture stop S is disposed adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2 and the third lens group G3, and the lens group Ln corresponds to the fourth lens group G4.

[0114] Hereinafter, the configurations of the respective lens groups will be described. The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L201 with a convex shape on the object side, a negative meniscus lens L202 with a convex shape on the object side, a negative meniscus lens L203 with a convex shape on the object side, and a positive meniscus lens L204 with a convex shape on the object side. Note that each lens surface on the image side of the lens L202 and the lens L204 is an aspherical surface. Further, the lens L204 corresponds to the lens "L1p" in the present invention, and the lens surface on the image side of the lens L204 corresponds to the lens surface "CrG1r" in the present invention.

[0115] The second lens group G2 is composed of a cemented lens in which a negative meniscus lens L205 with a convex shape on the object side and a biconvex lens L206 are cemented together.

[0116] The third lens group G3 is composed of, in order from the object side, the aperture stop S, a cemented lens in which a biconvex lens L207 and a biconcave lens L208 are cemented together, a cemented lens in which a negative meniscus lens L209 with a convex shape on the object side and a positive meniscus lens L210 with a convex shape on the object side are cemented together, and a biconvex lens L211. Note that both surfaces of the lens L211 are aspherical surfaces. Further, the third lens group G3 corresponds to the lens group "LpMax" in the present invention, and the lens L211 corresponds to the lens "LpMp" in the present invention.

[0117] The fourth lens group G4 is composed of a negative meniscus lens L212 with a convex shape on the object side.

[0118] The fifth lens group G5 is composed of a biconvex lens L213 and a biconcave lens L214 in order from the object side. Both surfaces of the lens L213 are aspherical surfaces.

[0119] When the zoom lens of Example 2 changes from the wide-angle end to the telephoto end, the first lens group G1 moves toward the image side and then toward the object side with respect to the image plane, the second lens group G2 moves toward the image side and then toward the object side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side.

[0120] Also, when the zoom lens focuses from an infinite object to a close object, the fourth lens group G4 moves from the object side toward the image side along the optical axis.

[0121] The zoom lens can perform shake correction by using the lens L211 included in the third lens group G3 as an anti-shake group and moving the anti-shake group in a direction perpendicular to the optical axis.

[0122] (2) Numerical Examples Next, numerical examples applying specific numerical values of the zoom lens will be described. Table 5 shows the surface data of the zoom lens. Table 6 is the origin table of the zoom lens. Table 7 shows the surface numbers of the lenses included in each lens group constituting the zoom lens and the focal lengths of each lens group. Table 8 shows the aspherical coefficients of each aspherical surface. Also, FIGS. 6 to 8 respectively show the longitudinal aberration diagrams at the wide-angle end, the intermediate focal length state, and the telephoto end of the zoom lens when focused at infinity. And Table 21 shows the values of conditional expressions (1) to (14) and the respective values used in the calculation of conditional expressions (1) to (14).

[0123] [Table 5] Surface Number R D Nd ABV Object Plane ∞ ∞ 1 49.9199 2.0000 1.78436 45.77 2 20.0000 4.8247 3 36.9299 1.5000 1.72916 54.67 4 17.7030 0.2000 1.53610 41.21 5 ASP 17.1820 6.4517 6 100.7210 1.5000 1.72916 54.67 7 20.4815 2.6125 8 28.3348 4.6408 1.71736 29.50 9 115.4139 0.2000 1.53610 41.21 10 ASP 52.1147 D(10) 11 33.8489 1.0000 1.91970 23.36 12 14.8237 6.1699 1.72405 27.25 13 -210.0707 D(13) 14 S ∞ 2.0000 15 24.3756 4.8951 1.53845 72.92 16 -28.4241 1.0000 1.70018 56.32 17 55.9270 2.7897 18 25.6060 1.0000 1.77131 47.50 19 13.9069 3.6869 1.49700 81.61 20 54.8489 3.2852 21 ASP 26.7652 5.8021 1.49710 81.56 22 ASP -23.9208 D(22) 23 34.3910 1.0000 1.69680 55.46 24 17.8455 D(24) 25 ASP 24.0464 8.1846 1.49710 81.56 26 ASP -19.4330 0.1000 27 -34.7778 1.2000 1.72604 54.84 28 23.4576 D(28) 29 ∞ 2.5000 1.51680 64.20 30 ∞ 1.0000

[0124] [Table 6] Wide-angle end Medium focal length Telephoto end f 15.46 21.85 29.10 Fno. 2.89 3.61 4.12 ω 56.72 45.30 36.73 Y 19.97 20.64 21.23 TL 120.62 117.02 118.06 D(10) 4.2008 2.8886 2.0000 D(13) 21.2547 9.7141 2.1000 D(22) 5.0787 3.1436 2.4987 D(24) 3.4065 5.3416 5.9865 D(28) 17.1402 26.3913 35.9284

[0125] [Table 7] Group Surface number Focal length G1 1-10 -14.84 G2 11-13 57.53 G3 14-22 26.30 G4 23-24 -54.59 G5 25-28 -541.46

[0126] [Table 8] Surface number K A4 A6 A8 A10 5 0.00000E+00 -7.13353E-06 -2.73137E-08 -1.73885E-11 0.00000E+00 10 0.00000E+00 -2.16483E-05 -3.23519E-08 -1.69294E-10 0.00000E+00 21 0.00000E+00 -1.84352E-05 2.43101E-08 8.28668E-11 0.00000E+00 22 0.00000E+00 3.13539E-05 -5.21245E-08 1.08634E-10 0.00000E+00 25 0.00000E+00 1.44636E-05 -3.13467E-08 3.20638E-10 -9.57521E-13 26 0.00000E+00 4.11894E-05 -1.81690E-08 2.54212E-10 -6.03157E-13

Example

[0127] (1) Optical configuration of the zoom lens FIG. 9 is a cross-sectional view showing the lens configurations at infinity focus at the wide-angle end and the telephoto end of the zoom lens according to Example 3 of the present invention. The zoom lens includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed within the second lens group G2. In this embodiment, the intermediate group corresponds to the second lens group G2, and the lens group Ln corresponds to the third lens group G3, respectively.

[0128] Hereinafter, the configurations of the respective lens groups will be described. The first lens group G1 includes, in order from the object side, a negative meniscus lens L301 with a convex shape on the object side, a negative meniscus lens L302 with a convex shape on the object side, a biconcave lens L303, and a biconvex lens L304. Note that each lens surface on the image side of the lens L302 and the lens L304 is an aspherical surface. Also, the lens L304 corresponds to the lens "L1p" in the present invention, and the lens surface on the image side of the lens L304 corresponds to the lens surface "CrG1r" in the present invention, respectively.

[0129] The second lens group G2 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L305 with a convex shape on the object side and a biconvex lens L306 are cemented together, an aperture stop S, a cemented lens in which a biconcave lens L307 and a biconvex lens L308 are cemented together, a positive meniscus lens L309 with a convex shape on the object side, and a biconvex lens L310. Note that both surfaces of the lens L310 are aspherical surfaces. Also, the second lens group G2 corresponds to the lens group "LpMax" in the present invention, and the lens L310 corresponds to the lens "LpMp" in the present invention.

[0130] The third lens group G3 is composed of a negative meniscus lens L311 with a concave shape on the object side.

[0131] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L312 and a biconcave lens L313. Both surfaces of the lens L312 are aspherical surfaces.

[0132] When the zoom lens of Example 3 is zoomed from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side after moving toward the image side with respect to the image plane, the second lens group G2 moves toward the object side, the third lens group G3 moves toward the object side, and the fourth lens group G4 moves toward the object side.

[0133] Also, when the zoom lens focuses from an infinite object to a close object, the third lens group G3 moves from the object side toward the image side along the optical axis.

[0134] The zoom lens can perform shake correction by moving the lens L310 included in the second lens group G2 as an anti-shake group in a direction perpendicular to the optical axis.

[0135] (2) Numerical Example Next, a numerical example applying the specific numerical values of the zoom lens will be described. Table 9 shows the surface data of the zoom lens. Table 10 is the origin table of the zoom lens. Table 11 shows the surface numbers of the lenses included in each lens group constituting the zoom lens and the focal lengths of each lens group. Table 12 shows the aspherical coefficients of each aspherical surface. Also, FIGS. 10 to 12 respectively show the longitudinal aberration diagrams at infinity focus at the wide-angle end, the intermediate focal length state, and the telephoto end of the zoom lens. And Table 21 shows the values of conditional expressions (1) to (14) and the respective values used in the calculations of conditional expressions (1) to (14).

[0136] [Table 9] Surface number R D Nd ABV Object surface ∞ ∞ 1 45.9665 2.0000 1.91082 35.25 2 20.0000 4.6653 3 35.8656 1.5000 1.72916 54.67 4 19.1538 0.2000 1.53610 41.21 5 ASP 16.9422 7.5065 6 -78.2089 1.5000 1.72916 54.67 7 25.2371 2.0427 8 37.1407 4.9633 1.71736 29.50 9 -62.4250 0.2000 1.53610 41.21 10 ASP -94.7173 D(10) 11 20.0044 1.0000 1.91082 35.25 12 15.5086 4.4513 1.68046 33.39 13 -312.6741 2.1000 14 S ∞ 2.5110 15 -63.1697 1.0000 1.91082 35.25 16 11.7699 4.3762 1.63416 61.14 17 629.8056 0.1000 18 22.9325 2.6332 1.49700 81.61 19 78.5401 4.6758 20 ASP 36.8447 4.2746 1.49710 81.56 21 ASP -22.3539 D(21) 22 -65.7587 1.0000 1.72916 54.67 23 -672.0766 D(23) 24 ASP 48.6211 5.2314 1.49710 81.56 25 ASP -18.8806 0.1182 26 -44.4585 1.2000 1.72916 54.67 27 30.8496 D(27) 28 ∞ 2.5000 1.51680 64.20 29 ∞ 1.0000

[0137] [Table 10] Wide-angle end Intermediate focal length Telephoto end f 15.45 21.85 29.11 Fno. 2.88 3.61 4.12 ω 56.68 43.76 34.79 Y 19.97 20.64 21.23 TL 120.00 115.76 115.50 D(10) 22.4143 10.0680 2.0000 D(21) 3.0925 7.4275 14.3355 D(23) 8.9418 8.9357 6.0656 D(27) 22.8019 26.5746 30.3516

[0138] [Table 11] Group Surface number Focal length G1 1-10 -17.97 G2 11-21 27.92 G4 22 - 23 - 100.04 G5 24 - 27 - 400.00

[0139] [Table 12] Surface number K A4 A6 A8 A10 5 0.00000E+00 - 2.38163E - 05 - 4.78409E - 08 - 1.47334E - 10 0.00000E+00 10 0.00000E+00 - 6.06540E - 06 6.24989E - 10 - 1.49920E - 10 0.00000E+00 20 0.00000E+00 - 3.54582E - 05 - 1.04141E - 07 - 7.27066E - 11 0.00000E+00 21 0.00000E+00 - 5.56397E - 06 - 1.05803E - 07 - 4.01537E - 10 0.00000E+00 24 0.00000E+00 - 3.56136E - 05 1.23145E - 07 - 2.04005E - 09 6.67569E - 12 25 0.00000E+00 3.07376E - 05 1.28930E - 07 - 1.98340E - 09 6.50202E - 12

Example

[0140] (1) Optical configuration of the zoom lens Figure 13 is a cross - sectional view showing the lens configurations at infinity focus at the wide - angle end and telephoto end of the zoom lens according to Example 4 of the present invention. The zoom lens includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a sixth lens group G6 having a negative refractive power. The aperture stop S is disposed adjacent to the object side of the third lens group G3. In this example, the intermediate group is composed of the second lens group G2, the third lens group G3, and the fourth lens group G4, and the lens group Ln corresponds to the fifth lens group G5.

[0141] The configurations of the respective lens groups will be described below. The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L401 with a convex shape on the object side, a negative meniscus lens L402 with a convex shape on the object side, a biconcave lens L403, and a positive meniscus lens L404 with a convex shape on the object side. Note that each lens surface on the image side of the lens L402 and the lens L404 is an aspherical surface. Further, the lens L404 corresponds to the lens "L1p" in the present invention, and the lens surface on the image side of the lens L404 corresponds to the lens surface "CrG1r" in the present invention, respectively.

[0142] The second lens group G2 is composed of a cemented lens in which a negative meniscus lens L405 with a convex shape on the object side and a biconvex lens L406 are cemented together.

[0143] The third lens group G3 is composed of, in order from the object side, a diaphragm S, a cemented lens in which a biconvex lens L407 and a biconcave lens L408 are cemented together, and a cemented lens in which a negative meniscus lens L409 with a convex shape on the object side and a positive meniscus lens L410 with a convex shape on the object side are cemented together.

[0144] The fourth lens group G4 is composed of a biconvex lens L411. Both surfaces of the lens L411 are aspherical surfaces. Further, the fourth lens group G4 corresponds to the lens group "LpMax" in the present invention, and the lens L411 corresponds to the lens "LpMp" in the present invention, respectively.

[0145] The fifth lens group G5 is composed of a negative meniscus lens L412 with a convex shape on the object side.

[0146] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L413 and a biconcave lens L414. Both surfaces of the lens L413 are aspherical surfaces.

[0147] In the zoom lens of Example 4, when zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the object side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 moves toward the object side.

[0148] Also, when focusing from an infinite object to a close object, the fifth lens group G5 moves from the object side toward the image side along the optical axis in the zoom lens.

[0149] In the zoom lens, by using L411 constituting the fourth lens group G4 as an anti-shake group and moving the anti-shake group in a direction perpendicular to the optical axis, shake correction can be performed.

[0150] (2) Numerical Example Next, a numerical example applying the specific numerical values of the zoom lens will be described. Table 13 shows the surface data of the zoom lens. Table 14 is the origin table of the zoom lens. Table 15 shows the surface numbers of the lenses included in each lens group constituting the zoom lens and the focal lengths of each lens group. Table 16 shows the aspherical coefficients of each aspherical surface. Further, FIGS. 14 to 16 respectively show the longitudinal aberration diagrams at the wide-angle end, the intermediate focal length state, and the telephoto end of the zoom lens when focused at infinity. And Table 21 shows the values of conditional expressions (1) to (14) and the respective values used in the calculations of conditional expressions (1) to (14).

[0151] [Table 13] Surface Number R D Nd ABV Object Plane ∞ ∞ 1 42.8582 2.0000 1.91082 35.25 2 20.0000 5.9132 3 57.1247 1.5000 1.73647 53.21 4 24.1922 0.2000 1.53610 41.21 5 ASP 20.5048 6.9517 6 -106.4452 1.5000 1.73014 54.47 7 23.2844 1.9588 8 25.9803 3.7932 1.85056 24.21 9 134.1277 0.2000 1.53610 41.21 10 ASP 123.9146 D(10) 11 27.7803 1.0000 1.91733 25.65 12 16.0429 4.1181 1.64065 33.41 13 -950.9894 D(13) 14 S ∞ 2.8785 15 43.3018 4.0046 1.54824 71.30 16 -20.4613 1.0000 1.71210 53.95 17 42.4758 0.2273 18 23.8726 1.0000 1.80697 38.92 19 15.7558 3.8401 1.51721 76.95 20 355.5760 D(20) 21 ASP 27.4262 7.0734 1.48614 82.92 22 ASP -21.2352 D(22) 23 38.1860 1.0000 1.68905 57.02 24 18.4614 D(24) 25 ASP 25.2455 9.4359 1.50250 76.18 26 ASP -17.1401 0.1150 27 -27.1371 1.2000 1.72791 54.74 28 25.1493 D(28) 29 ∞ 2.5000 1.51680 64.20 30 ∞ 1.0000

[0152] [Table 14] Wide-angle end Middle focal length Telephoto end f 15.45 21.85 29.10 Fno. 2.88 3.61 4.14 ω 56.69 45.61 36.70 Y 19.97 20.64 21.23 TL 120.00 120.00 120.00 D(10) 9.2631 5.9048 2.3457 D(13) 15.3884 8.8201 4.7874 D(20) 5.8497 4.3952 3.1279 D(22) 4.9839 2.1108 2.7002 D(24) 3.0300 7.0471 5.5293 D(28) 17.0751 27.3122 37.0998

[0153] [Table 15] Group Surface Number Focal Length G1 1-10 -16.41 G2 11-13 59.86 G3 14-20 401.05 G4 21-22 25.85 G5 23-24 -52.97 G6 25-28 -400.00

[0154] [Table 16] Surface Number K A4 A6 A8 A10 5 0.00000E+00 -2.15513E-05 -3.54019E-08 -1.03182E-10 0.00000E+00 10 0.00000E+00 8.64701E-06 6.06914E-09 -3.21414E-12 0.00000E+00 21 0.00000E+00 -1.79955E-05 5.40156E-09 1.53060E-10 0.00000E+00 22 0.00000E+00 4.21377E-05 -8.37172E-08 4.00374E-10 0.00000E+00 25 0.00000E+00 1.97469E-05 -6.09841E-08 3.24007E-10 -1.67902E-13 26 0.00000E+00 5.31544E-05 -1.54076E-08 2.14204E-10 6.55586E-13

Example

[0155] (1) Optical configuration of the zoom lens FIG. 17 is a cross-sectional view showing the lens configurations at infinity focus at the wide-angle end and the telephoto end of the zoom lens according to Example 5 of the present invention. The zoom lens includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a sixth lens group G6 having a negative refractive power. The aperture stop S is disposed adjacent to the object side of the third lens group G3. In this embodiment, the intermediate group is composed of the second lens group G2, the third lens group G3, and the fourth lens group G4, and the lens group Ln corresponds to the fifth lens group G5.

[0156] Hereinafter, the configurations of each lens group will be described. The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L501 with a convex object side, a negative meniscus lens L502 with a convex object side, a biconcave lens L503, and a biconvex lens L504. Note that each lens surface on the image side of the lens L502 and the lens L504 is an aspherical surface. Further, the lens L504 corresponds to the lens "L1p" in the present invention, and the lens surface on the image side of the lens L504 corresponds to the lens surface "CrG1r" in the present invention.

[0157] The second lens group G2 is composed of a cemented lens in which a negative meniscus lens L505 with a convex object side and a biconvex lens L506 are cemented together.

[0158] The third lens group G3 is composed of, in order from the object side, a diaphragm S, a negative meniscus lens L507 with a concave shape on the object side, and a cemented lens in which a biconvex lens L508 and a biconcave lens L509 are cemented together.

[0159] The fourth lens group G4 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L510 with a convex shape on the object side and a positive meniscus lens L511 with a convex shape on the object side are cemented together, and a biconvex lens L512. Both surfaces of the lens L512 are aspherical surfaces. Further, the fourth lens group G4 corresponds to the lens group "LpMax" in the present invention, and the lens L512 corresponds to the lens "LpMp" in the present invention.

[0160] The fifth lens group G5 is composed of a negative meniscus lens L513 with a convex shape on the object side.

[0161] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L514 and a biconcave lens L515. Both surfaces of the lens L515 are aspherical surfaces.

[0162] When the zoom lens of Example 5 is zoomed from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side after moving toward the image side with respect to the image plane, the second lens group G2 moves toward the object side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 moves toward the object side.

[0163] Further, when the zoom lens focuses from an infinite object to a close object, the fifth lens group G5 moves from the object side toward the image side along the optical axis.

[0164] The zoom lens can perform shake correction by moving the anti-shake group, which is the lens L512 included in the fourth lens group G4, in a direction perpendicular to the optical axis.

[0165] (2) Numerical Examples Next, a numerical example applying the specific numerical values of the zoom lens will be described. Table 17 shows the surface data of the zoom lens. Table 18 is the origin table of the zoom lens. Table 19 shows the surface numbers of the lenses included in each lens group constituting the zoom lens and the focal lengths of each lens group. Table 20 shows the aspherical coefficients of each aspherical surface. Also, FIGS. 18 to 20 respectively show the longitudinal aberration diagrams at the wide-angle end, the intermediate focal length state, and the telephoto end of the zoom lens of Example 5 when focused at infinity. And Table 21 shows the values of conditional expressions (1) to (14) and the respective values used in the calculations of conditional expressions (1) to (14).

[0166] [Table 17] Surface number R D Nd ABV Object plane ∞ ∞ 1 64.4935 2.0000 1.80420 46.50 2 20.0000 5.8149 3 44.3380 1.5000 1.72916 54.67 4 21.1456 0.2000 1.53610 41.21 5 ASP 19.2295 7.5156 6 -150.7078 1.5000 1.72916 54.67 7 30.8746 2.0751 8 39.1591 4.7734 1.85883 30.00 9 -122.1827 0.2000 1.53610 41.21 10 ASP -337.0680 D(10) 11 25.7483 1.0000 1.91082 35.25 12 16.7808 3.8598 1.63680 49.15 13 -108.4616 D(13) 14 S ∞ 2.7762 15 -36.6701 1.0000 1.82332 36.47 16 -663.6925 0.1000 17 24.1845 3.9673 1.54571 51.63 18 -33.7101 1.0000 1.72916 54.67 19 119.1041 D(19) 20 29.2776 1.0000 1.83338 40.48 21 13.7692 4.4721 1.49700 81.61 22 158.7714 2.5000 23 ASP 30.8545 5.1765 1.49710 81.56 24 ASP -33.1652 D(24) 25 29.6714 1.0000 1.73357 53.78 26 20.5408 D(26) 27 21.5900 8.4030 1.53350 56.48 28 -29.7187 0.1000 29 ASP -57.0454 1.2000 1.76029 49.12 30 ASP 20.4524 D(30) 31 ∞ 2.5000 1.51680 64.20 32 ∞ 1.0000

[0167] [Table 18] Wide-angle end Middle focal length Telephoto end f 15.45 21.85 29.10 Fno. 2.88 3.60 4.12 ω 56.68 44.98 36.07 Y 19.97 20.64 21.23 TL 120.00 116.50 117.59 D(10) 20.3946 9.6191 2.0000 D(13) 4.3222 5.1184 5.3378 D(19) 5.4505 3.2882 2.5000 D(24) 2.0059 2.0030 4.6652 D(26) 3.4503 4.3535 6.1135 D(30) 17.7429 25.4839 30.3398

[0168] [Table 19] Group Surface Number Focal Length G1 1-10 -20.57 G2 11-13 40.26 G3 14-19 -100.00 G4 20-24 32.69 G5 25-26 -95.42 G6 27-30 -400.00

[0169] [Table 20] Surface Number K A4 A6 A8 A10 5 0.00000E+00 -1.33896E-05 -4.03264E-08 -4.74820E-12 0.00000E+00 10 0.00000E+00 -7.18688E-06 -4.32457E-09 -4.62078E-11 0.00000E+00 23 0.00000E+00 -1.87086E-05 4.43421E-08 1.89540E-10 0.00000E+00 24 0.00000E+00 9.14539E-06 9.72993E-09 4.52486E-11 0.00000E+00 29 0.00000E+00 -1.25529E-05 3.09804E-08 -3.76634E-10 0.00000E+00 30 0.00000E+00 3.30936E-06 4.84433E-08 -5.50774E-10 0.00000E+00

[0170] [Table 21] Example 1 Example 2 Example 3 Example 4 Example 5 Conditional Expression (1) |f1| / |fpMax| 0.57 0.56 0.64 0.63 0.63 Conditional expression (2) βpw -0.63 -0.70 -0.61 -0.62 -0.61 Conditional expression (3) f1 / fw -1.23 -0.96 -1.16 -1.06 -1.33 Conditional expression (4) fn / fpMax -2.70 -2.08 -3.58 -2.05 -2.92 Conditional expression (5) frt / ft 1.02 0.96 1.03 0.95 0.98 Conditional expression (6) βn1 1.39 1.65 1.41 1.69 1.38 Conditional expression (7) βn12 1.29 1.49 1.42 1.52 1.24 Conditional expression (8) |{1-(βn1×βn1)}×(βn2×βn2)| 0.80 1.40 1.00 1.50 0.73 Conditional expression (9) | CrG1r / fw | 1981.08 3.37 6.13 8.02 21.82 Conditional expression (10) (fw×tanω) / BFw 1.19 1.19 0.92 1.19 1.15 Conditional expression (11) νdLpMp 80.01 81.56 81.56 82.92 81.56 Conditional expression (12) νdL1p 22.33 29.50 29.50 24.21 30.00 Conditional expression (13) NdL1p 1.86 1.72 1.72 1.85 1.86 Conditional expression (14) |BFt - BFw| / TLw 0.16 0.16 0.06 0.17 0.10 frt 29.55 27.94 30.01 27.54 28.62 BFw 19.80 19.80 25.46 19.74 20.40 BFt 39.65 38.59 33.01 39.76 33.00

Industrial Applicability

[0171] According to the present invention, a zoom lens and an imaging device that are small and have high optical performance can be provided.

Explanation of Symbols

[0172] G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group CG Cover glass IP Imaging plane (image plane) S Aperture stop W Wide-angle end T Telephoto end FNo. F-number ω Half field angle

Claims

1. It is composed of, in order from the object side, a first lens group having a negative refractive power, an intermediate group composed of one or more lens groups and having a positive refractive power as a whole, a lens group Ln having a negative refractive power, and a final lens group having a negative refractive power, The intermediate group includes a lens group LpMax, The lens group LpMax has the strongest positive refractive power among the lens groups included in the intermediate group, A zoom lens that performs zooming or focusing by changing the distance between adjacent lens groups, The final lens group moves from the image side to the object side along the optical axis during zooming from the wide-angle end to the telephoto end, A zoom lens characterized by satisfying the following conditional expression. 0.05 ≦ |f1| / |fpMax| ≦ 0.65... (1) However, f1: The focal length of the first lens group fpMax: The focal length of the lens group LpMax

2. The zoom lens according to Claim 1, which satisfies the following conditional expression. -1.50 ≦ f1 / fw ≦ -0.05... (3) However, f1: The focal length of the first lens group fw: The focal length of the zoom lens at infinity focus at the wide-angle end

3. The zoom lens according to Claim 1 or Claim 2, which satisfies the following conditional expression. -4.0 ≦ fn / fpMax ≦ -1.5... (4) However, fn: The focal length of the lens group Ln fpMax: The focal length of the lens group LpMax

4. The zoom lens according to any one of Claims 1 to 3, which satisfies the following conditional expression. 0.05 ≦ frt / ft ≦ 1.50... (5) However, frt: The combined focal length from the intermediate group to the final lens group at infinity focus at the telephoto end ft: The focal length of the zoom lens at infinity focus at the telephoto end

5. The zoom lens according to any one of Claims 1 to 4, satisfying the following conditional expression. 1.00 ≦ βn1 ≦ 5.00... (6) However, βn1: The lateral magnification of the lens group Ln at infinity focus at the wide-angle end

6. The zoom lens according to any one of Claims 1 to 5, satisfying the following conditional expression. 1.00 ≦ βn12 ≦ 5.00... (7) However, βn12: The combined lateral magnification of the lens group Ln and the final lens group at infinity focus at the wide-angle end

7. The zoom lens according to any one of Claims 1 to 6, satisfying the following conditional expression when the lens group Ln moves along the optical axis when focusing from infinity to a nearby object. 0.6 ≦ |{1 - (βn1 × βn1)} × (βn2 × βn2)| ≦ 15.0... (8) However, βn1: The lateral magnification of the lens group Ln at infinity focus at the wide-angle end βn2: The lateral magnification of the final lens group at infinity focus at the wide-angle end

8. The zoom lens according to any one of Claims 1 to 7, satisfying the following conditional expression. 1.00 ≦ |CrG1r / fw|... (9) However, CrG1r: The radius of curvature of the most image-side lens surface of the first lens group fw: The focal length of the zoom lens at infinity focus at the wide-angle end

9. The zoom lens according to any one of claims 1 to 8, which satisfies the following conditional expressions. 0.65 ≦ (fw × tan ω) / BFw ≦ 2.30... (10) However, fw: The focal length of the zoom lens at infinity focus at the wide-angle end ω: The half field angle of the zoom lens at infinity focus at the wide-angle end BFw: The distance on the optical axis between the most image-side lens surface and the image surface of the zoom lens at infinity focus at the wide-angle end

10. The zoom lens according to any one of claims 1 to 9, wherein the lens group LpMax has at least one lens LpMp having a positive refractive power and satisfies the following conditional expressions. 45.0 ≦ νdLpMp ≦ 98.0... (11) However, νdLpMp: The Abbe number of the lens LpMp at the d line

11. The zoom lens according to any one of claims 1 to 10, wherein the first lens group has at least one lens L1p having a positive refractive power and satisfies the following conditional expressions. 20.0 ≦ νdL1p ≦ 50.0... (12) However, νdL1p: The Abbe number of the lens L1p at the d line

12. The zoom lens according to any one of claims 1 to 11, wherein the first lens group has at least one lens L1p having a positive refractive power and satisfies the following conditional expressions. 1.70 ≦ NdL1p ≦ 2.20... (13) However, NdL1p: The refractive index of the lens L1p at the d line

13. The zoom lens according to any one of claims 1 to 12, which satisfies the following conditional expressions. |BFT - BFw| / TLw ≤ 0.30...(14) However, BFT: The distance on the optical axis between the most image-side lens surface of the zoom lens and the image plane at infinity focus at the telephoto end BFw: The distance on the optical axis between the most image-side lens surface of the zoom lens and the image plane at infinity focus at the wide-angle end TLw: The overall optical length of the zoom lens at infinity focus at the wide-angle end

14. An imaging device comprising the zoom lens according to any one of Claims 1 to 13, and an imaging element disposed on the image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

Images