JP2015079238A - Zoom lens and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens that has a sufficient zooming rate, can provide high optical performance, and may be made even smaller and lighter.SOLUTION: A zoom lens comprises lens groups G1 to G4 that are respectively negative, positive, negative and positive. The first lens group G1 includes at least two negative lenses L1, L2 and a single positive lens L3. The second lens group G2 has a function of image-shaking correction by moving at least some lens L6 in a surface that crosses an optical axis. The third lens group G comprises a single negative lens L7.

Description

  The present invention relates to a zoom lens and an imaging apparatus.

  Conventionally, a negative lead type zoom lens preceded by a lens group having a negative refractive power as a whole is widely used because it is relatively easy to widen the angle of view and is advantageous for downsizing the front lens diameter. ing.

  Such a negative lead type zoom lens is required to have high optical performance during zooming from the wide-angle end to the telephoto end. For this reason, various zoom lenses having a multi-group configuration have been developed.

  Among them, in order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, and a third lens group having a negative refractive power as a whole, A zoom lens including a fourth lens group having a positive refractive power as a whole is known (see, for example, Patent Documents 1 to 4).

  Specifically, in Patent Document 1 below, in the above-described four-group zoom lens including the negative, positive, negative, and positive lens groups, the first lens is used for zooming from the wide angle end to the telephoto end. The second lens group and the second lens group move toward the object side so that the mutual air gap becomes narrow, and the second lens group and the third lens group move so that the mutual air gap increases, and the third lens group and the second lens group A zoom lens having a configuration in which the four lens groups move so that the air gap between them is narrowed, the third lens group and the fourth lens group are each composed of one lens, and has an aspherical surface is disclosed. Yes.

  In Patent Document 2 below, in the four-group zoom lens composed of the above-described negative, positive, negative, and positive lens groups, the first lens group has an image plane at the time of zooming from the wide-angle end to the telephoto end. A zoom lens is disclosed that moves along a convex locus to the side, the third lens group is composed of a single negative lens, and defines the material and shape of the third lens group. Further, Patent Document 2 discloses a zoom lens configured to move the third lens group in a direction substantially perpendicular to the optical axis as an image shake correction mechanism (camera shake correction mechanism) that corrects image shake due to camera shake or the like. Yes.

  In the following Patent Document 3 and Patent Document 4, in the four-group zoom lens composed of the above-described negative, positive, negative, and positive lens groups, a lens disposed closest to the image plane of the second lens group is light-transmitted. A function of correcting image blur by moving in a direction substantially perpendicular to the axis, a configuration in which the third lens group has a focusing function from an object at infinity to a close object, A zoom lens having a configuration in which the power and thickness of the three lens groups are defined and the lateral magnification of the lens located closest to the image plane of the second lens group is defined.

JP 2001-116992 A JP 2006-208889 A JP 2012-133229 A JP 2013-015778 A

  However, the zoom lens disclosed in Patent Document 1 has a certain degree of optical performance while simplifying its configuration, but has a drawback that it is difficult to secure a lens that corrects image blur. Further, since the refractive power of the third lens group and the fourth lens group is weak, the arrangement of the telephoto type refractive power between the second lens group and the third lens group at the telephoto end is particularly weakened, and the total lens length is shortened. Is difficult.

  On the other hand, in the zoom lens disclosed in Patent Document 2, although the third lens group has an image blur correction function, focusing (referred to as focusing) from an object at infinity to a close object is performed. Since the third lens group is also used for image blur correction, it is difficult to reduce the size of the apparatus. Further, when focusing is performed by moving the fourth lens group in the optical axis direction, it is difficult to shorten the entire lens length by increasing the amount of movement of the fourth lens group.

  On the other hand, in the zoom lenses disclosed in Patent Document 3 and Patent Document 4, the lens located closest to the image side in the second lens group is provided with an image blur correction function so that an object from an infinite object to a close object can be obtained. Focusing is performed by the third lens group. In this case, the movement amount of the fourth lens group can be suppressed and the total lens length can be shortened. However, since the final lens group is fixed, particularly when a large image sensor is used, the final lens group is increased in size, and as a result, it is difficult to reduce the weight of the zoom lens.

  One of the aspects of the present invention has been proposed in view of such a conventional situation, and has an adequate zoom ratio, and image plane fluctuations accompanying zooming and aberrations that occur during image blur correction. It is an object of the present invention to provide a zoom lens and an imaging apparatus that can obtain high optical performance by properly correcting the above and reduce the total optical length, and can be further reduced in size and weight. I will.

[1] The zoom lens according to the first aspect of the present invention includes, in order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, and a whole A third lens group having a negative refractive power as a whole and a fourth lens group having a positive refractive power as a whole, and an air gap between the lens groups at the time of zooming from the wide-angle end to the telephoto end. It is a zoom lens that changes The first lens group includes at least two negative lenses and one positive lens. The second lens group has a function of correcting image blur by moving at least a part of the lens within a plane intersecting the optical axis. The third lens group is composed of one negative lens.

[2] In the zoom lens according to the above [1], the amount of movement in the optical axis direction of the second lens group upon zooming from the wide-angle end to the telephoto end and M _2, the telephoto end from the wide-angle end the amount of movement in the optical axis direction of the fourth lens group during zooming into and M _4, a composite focal length of the fourth lens group and f _4, a focal length of the entire system at the telephoto end f when the _{t, 0.05 <M 4 / M} 2 <1.0, 0.8 < may be configured to satisfy the relation _{f 4} / _f t <5.0.

[3] In the zoom lens according to [1] or [2], the lens located closest to the image plane among the plurality of lenses constituting the second lens group is moved within a plane intersecting the optical axis. The image blur may be corrected by causing the image blur to be corrected.

[4] In the zoom lens according to [1] or [2], the third lens from the object side among the plurality of lenses constituting the second lens group is within a plane intersecting the optical axis. The image blur may be corrected by moving the image.

[5] In the zoom lens according to any one of [1] to [4], the negative lens included in the third lens group is a biconcave lens in which both surfaces are concave, and at least 1 The surface may be an aspherical surface.

[6] In the zoom lens according to any one of [1] to [5], the fourth lens group includes a single positive lens, and the positive lens included in the fourth lens group includes Further, it may be a meniscus lens having a convex image surface side and at least one surface being an aspherical surface.

[7] In the zoom lens according to the above [6], the paraxial curvature radius of the object side of the fourth lens group and r _41, the focal length of the fourth lens group when the f _4, -10 The structure may satisfy the relationship of 0.0 <r ₄₁ / f ₄ <0.0.

[8] In the zoom lens according to [6], the refractive index with respect to the d-line of the negative lens constituting the third lens group is nd _3, and the refraction with respect to the d-line of the positive lens constituting the fourth lens group. When the ratio is nd ₄ , a configuration satisfying the relationship of 1.65 <nd ₃ , 0.005 <nd ₃ -nd ₄ may be used.

[9] In the zoom lens according to any one of [1] to [8], an amount of movement of the second lens group in the optical axis direction upon zooming from the wide-angle end to the telephoto end is set. M ₂ , the amount of movement of the third lens group in the optical axis direction during zooming from the wide-angle end to the telephoto end is M ₃ , the focal length of the third lens group is f ₃ , and the telephoto end the focal length of the entire system is taken as _{f t, 0.55 <M 3 /} M 2 <1.0, 0.1 < at _{| f 3 / f t | <} 0.8 relationship configuration which satisfies the There may be.

[10] In the zoom lens according to the above [9], the paraxial curvature radius of the object side of the third lens group and r _31, the paraxial curvature radius of the image side of the third lens group and r ₃₂ In this case, a configuration satisfying the relationship of 0.3 <(r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ ) <1.0 may be adopted.

[11] In the zoom lens according to any one of [1] to [10], the second lens group includes a second a lens having a positive refractive power and a positive refractive power in order from the object side. It may be configured to include a second b lens having a second refractive index and a second c lens having a positive refractive power.

[12] In the zoom lens according to the above [11], the focal length of the second lens group and f _2, a focal length of the entire system at the telephoto end when a f _t, 0.1 <f ₂ / A configuration that satisfies the relationship of f _t <0.8 may be adopted.

[13] In the zoom lens according to [11] or [12], the 2a lens is a biconvex lens in which both surfaces thereof are convex, and at least one surface is an aspheric surface, and the 2b lens. May be a cemented lens in which a negative lens and a positive lens are cemented in order from the object side.

In the zoom lens according to [14] wherein [13], the focal length of the 2b lens and _{f 2b,} the focal length of the entire system at the telephoto end when a _{f t, 2.0 <f 2b /} f A configuration satisfying the relationship of ₂ <20.0 may be adopted.

[15] In the zoom lens according to [13], 0.8 <f _2a / f when the focal length of the second lens is f _2a and the focal length of the second lens group is f _{2. 2} <1.8 may be satisfied.

[16] In the zoom lens according to [13], when the focal length of the second c lens is f _2c and the focal length of the second lens group is f ₂ , 2.5 <f _2c / f ₂ <5.0 may be satisfied.

[17] In the zoom lens according to [13], when the paraxial radius of curvature of the cemented surface of the cemented lens constituting the second b lens is r _2b2 and the focal length of the second b lens is f _2b. , 0.0 <r _2b2 / f _2b <0.3.

[18] In the zoom lens according to the above [13], when the paraxial curvature radius of the object side of the 2a lens and r _2a1, the paraxial curvature radius of the image side of the 2a lens was r _2a2 In addition,
A configuration satisfying the relationship of −1.0 <(r _2a1 + r _2a2 ) / (r _2a1 −r _2a2 ) <− 0.5 may be _employed .

[19] In the zoom lens according to any one of [13] to [18], the second lens b is formed by bonding a negative lens having a convex surface on the object side and a positive lens having convex surfaces on both surfaces. It may be a configuration that is a cemented lens.

[20] In the zoom lens according to any one of [11] to [19], the second c lens may be a meniscus positive lens having a convex object side.

[21] The zoom lens according to any one of [11] to [20], wherein a diaphragm is disposed between the second a lens and the second b lens.

[22] In the zoom lens according to any one of [1] to [21], the first lens group includes, in order from the object side, a negative lens having a convex surface on the object side, and concave surfaces on both surfaces. A negative lens, and a positive lens having a convex surface on the object side, and at least one surface of any one of the lenses constituting the first lens group may be an aspherical surface. Good.

[23] In the zoom lens according to the above [22], the focal length of the first lens group and f _1, the focal length of the entire system at the telephoto end when a f _t, 0.2 <| f ₁ A configuration satisfying the relationship of / f _t | <0.8 may be adopted.

[24] An imaging device according to a second aspect of the present invention provides a solid-state imaging that captures an image formed by the zoom lens according to any one of [1] to [23] and the zoom lens. An element.

  As described above, according to the aspect of the present invention, in the four-group zoom lens including the negative, positive, negative, and positive lens groups, while having a sufficient zoom ratio (for example, about 3 times), High optical performance can be obtained by satisfactorily correcting image plane fluctuations due to zooming and aberrations that occur during image blur correction, and by reducing the overall optical length, it can be further reduced in size and weight. It is possible to provide a possible zoom lens and imaging device.

It is a block diagram of the zoom lens shown as one Embodiment of this invention. FIG. 2 is a configuration diagram illustrating lens arrangements at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to the first exemplary embodiment. FIG. 4 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 1. FIG. 3 is a lateral aberration diagram at the wide-angle end in the zoom lens according to Example 1; FIG. 3 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 1; FIG. 5 is a configuration diagram illustrating lens arrangements at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to the second exemplary embodiment. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 2. FIG. 6 is a lateral aberration diagram at the wide-angle end in the zoom lens according to Example 2. FIG. 6 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 2; FIG. 6 is a configuration diagram illustrating lens arrangements at a wide-angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to Embodiment 3; FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 3. 6 is a lateral aberration diagram at a wide-angle end in the zoom lens according to Example 3. FIG. FIG. 6 is a lateral aberration diagram at a telephoto end in the zoom lens according to Example 3; FIG. 6 is a configuration diagram illustrating lens arrangements at a wide-angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to a fourth exemplary embodiment. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 4. FIG. 10 is a lateral aberration diagram at a wide-angle end in the zoom lens according to Example 4; FIG. 10 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 4; FIG. 10 is a configuration diagram illustrating a lens arrangement at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to a fifth exemplary embodiment. It is a chart. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 5. FIG. 10 is a lateral aberration diagram at the wide-angle end in the zoom lens according to Example 5. FIG. 10 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 5; FIG. 10 is a configuration diagram illustrating a lens arrangement at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in a zoom lens according to a sixth exemplary embodiment. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 6. FIG. 12 is a lateral aberration diagram at the wide-angle end in the zoom lens according to Example 6; 12 is a lateral aberration diagram at a telephoto end in a zoom lens according to Example 6; FIG. FIG. 10 is a configuration diagram illustrating a lens arrangement at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to a seventh exemplary embodiment. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens of Example 7. 10 is a lateral aberration diagram at a wide-angle end in the zoom lens according to Example 7. FIG. FIG. 10 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 7; FIG. 10 is a configuration diagram illustrating lens arrangements at a wide angle end (W), an intermediate focal position (M), and a telephoto end (T) in the zoom lens according to an eighth exemplary embodiment. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the wide-angle end (W), the intermediate focal position (M), and the telephoto end (T) in the zoom lens according to the eighth exemplary embodiment. FIG. 10 is a lateral aberration diagram at the wide-angle end in the zoom lens according to Example 8; FIG. 10 is a lateral aberration diagram at the telephoto end in the zoom lens according to Example 8;

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that the lens data and the like exemplified in the following description are merely examples, and the present invention is not necessarily limited thereto, and can be appropriately modified and implemented without changing the gist thereof.

FIG. 1 is a configuration diagram of a zoom lens shown as an embodiment of the present invention.
As shown in FIG. 1, the zoom lens according to the present embodiment is used as an imaging optical system of an imaging apparatus such as an interchangeable lens system camera, a digital still camera, a digital video camera, or a surveillance camera.

  Specifically, the zoom lens shown in FIG. 1 includes, in order from the object side, a first lens group G1 having a negative refractive power as a whole, a second lens group G2 having a positive refractive power as a whole, and a negative as a whole. The third lens group G3 having a refractive power of 4 and the fourth lens group G4 having a positive refractive power as a whole are provided. That is, this zoom lens constitutes a four-group zoom lens composed of negative, positive, negative, and positive lens groups G1 to G4.

  The first lens group G1 includes at least two negative lenses L1 and L2 and one positive lens L3. Specifically, the first lens group G1 includes, in order from the object side, a negative lens L1 having a convex surface on the object side, a negative lens L2 having concave surfaces, and a positive lens having a convex surface on the object side. L3 is arranged. In addition, at least one surface of any lens constituting the first lens group G1 is an aspherical surface.

  In the first lens group G1, at least two negative lenses L1 and L2 are arranged in order from the object side. Among them, a negative lens L1 having a convex surface on the object side and a negative lens L2 having concave surfaces on both sides are disposed. Thereby, negative refractive power can be dispersed and coma and distortion at the wide-angle end can be corrected well. In particular, it is possible to satisfactorily correct coma at the wide-angle end by using a biconcave lens as the negative lens L2 located second from the object side.

  In the first lens group G1, a positive lens L3 having a convex surface on the object side is disposed after the two negative lenses L1 and L2 (image side). As a result, it is possible to satisfactorily correct chromatic aberration that occurs in the first lens group G1 and spherical aberration at the telephoto end.

  In the first lens group G1, at least one surface of any one of the lenses L1, L2, and L3 constituting the first lens group G1 is an aspherical surface. This makes it possible to satisfactorily correct field curvature at the wide-angle end and spherical aberration at the telephoto end. At this time, when the aspherical surface is provided on the most object side negative lens L1, the above-described effect can be most obtained. On the other hand, if the negative lens L2 located second from the object side is provided with an aspheric surface, the outer diameter of the negative lens L2 can be reduced.

  In the second lens group G2, a second a lens L4 having a positive refractive power, a second b lens L5 having a positive refractive power, and a second c lens L6 having a positive refractive power are arranged in order from the object side. It is a configuration.

  The second lens group G2 is a main lens group for performing zooming. The second lens group G2 is required to have a strong positive refractive power in order to shorten the total lens length. In response to such a demand, in the second lens group G2, the three lenses L4 to L6 have positive refracting power with the air gap as a boundary, thereby dispersing strong positive refracting power. In the zoom lens according to the present embodiment, by adopting such a configuration, it is possible to further correct the spherical aberration and further reduce the total length of the lens.

  The second a lens L4 is a biconvex lens whose both surfaces are convex, and at least one surface is an aspherical surface. The second b lens L5 includes a cemented lens in which a negative lens L5a and a positive lens L5b are cemented in order from the object side. The second c lens L6 is a positive lens having a convex surface on the object side.

  In general, in a four-group zoom lens composed of negative, positive, negative, and positive lens groups, the axial ray bundle is the largest on the object side of the second lens group G2, so that it is disposed on the most object side. In the second a lens L4, spherical aberration is likely to occur. Therefore, spherical aberration can be favorably corrected by making at least one surface of the second a lens L4 an aspherical surface. Moreover, size reduction can be achieved by making the 2a lens L4 into a biconvex lens.

  In the second b lens L5, the chromatic aberration generated in the second a lens L4 can be satisfactorily suppressed by disposing the negative lens L5a on the object side. In addition, spherical aberration is satisfactorily corrected by the cemented surface of the negative lens L5a and the positive lens L5b constituting the cemented lens.

  In the second b lens L5, it is preferable to dispose a meniscus negative lens L5a having a convex surface on the object side. Thereby, the space | interval required in order to arrange | position the aperture stop SP arrange | positioned between the 2a lens L4 and the 2b lens L5 can be suppressed to the minimum. Further, in the positive lens L5b, it is preferable to use a glass material having high anomalous dispersion in order to satisfactorily suppress chromatic aberration. However, a glass material with high anomalous dispersion has a high refractive index, which is disadvantageous from the viewpoint of miniaturization. For this reason, the positive lens L5b constituting the 2b lens group is a biconvex lens in which both surfaces are convex, thereby effectively ensuring positive refractive power and miniaturization. By adopting such a configuration, the entire length of the second lens group G2 can be suppressed. For example, when the lens barrel is retracted and compact storage is performed, the retracted thickness can be reduced.

  As the second c lens L6, it is preferable to use a positive lens having a convex surface on the object side. Further, by making the second c lens L6 a meniscus lens having a convex on the object side, the image blur is corrected when the second c lens L6 has a function of correcting the image blur while reducing the weight. The mechanism (image blur correction mechanism) can be downsized.

  The third lens group G3 includes one negative lens L7. Further, the negative lens L7 is a biconcave lens in which both surfaces are concave, and at least one surface is an aspherical surface.

  In the zoom lens according to the present embodiment, the third lens group G3 is configured by one negative lens L7, so that the weight can be reduced. In particular, in the zoom lens according to the present embodiment, since the third lens group G3 has a focusing function, the lens driving mechanism can be reduced in size by reducing the weight of the third lens group G3. .

  In the third lens group G3, by setting at least one surface of the negative lens L7 as an aspherical surface, various aberrations due to fluctuations during zooming and focusing, particularly coma, can be corrected well. Further, by making the negative lens L7 a biconcave lens, negative refractive power is dispersed on the object side and the image side. Thereby, it is possible to suppress field curvature and coma deterioration due to decentration.

  The fourth lens group G4 includes one positive lens L8. The positive lens L8 is a meniscus lens having a convex surface on the image surface side, and at least one surface is an aspherical surface.

    In the zoom lens according to the present embodiment, the fourth lens group G4 is configured by one positive lens L8, so that the weight can be reduced. In the fourth lens group G4, by making at least one surface of the positive lens L8 an aspherical surface, it is possible to satisfactorily correct field curvature at the time of zooming from the wide angle end to the telephoto end. Furthermore, the positive lens L8 is preferably a meniscus lens having a convex surface on the image side. As a result, for example, when the light beam reflected by the imaging surface of the solid-state image sensor or the optical filter enters the positive lens L8, the light beam reflected by the positive lens L8 is incident again on the imaging surface of the solid-state image sensor. Ghosting and the like can be suppressed.

  An aperture stop SP is disposed between the second a lens L4 and the second b lens L5 constituting the second lens group G2. The aperture stop SP limits the diameter (light quantity) of the light beam incident from the object side to the image plane IP side.

  In the zoom lens according to the present embodiment, the negative first lens group G1 and the negative third lens group G3 are disposed with the aperture stop SP interposed therebetween, so that it becomes easy to correct off-axis aberrations. Further, the total optical length of the telephoto end can be shortened by the telephoto effect by the negative third lens group G3 at the telephoto end.

  An optical block G is disposed between the fourth lens group G4 and the image plane IP. The optical block G corresponds to an optical filter, a face plate, a crystal low-pass filter, an infrared cut filter, or the like.

  In an imaging apparatus including the zoom lens according to the present embodiment and a solid-state imaging element, the image plane IP corresponds to the imaging plane of the solid-state imaging element. As the solid-state imaging device, for example, a photoelectric conversion device such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor device (CMOS) sensor can be used.

  In the imaging apparatus, light incident from the object side of the zoom lens according to the present embodiment finally forms an image on the imaging surface of the solid-state imaging device. Then, the light received by the solid-state imaging device is photoelectrically converted and output as an electrical signal, and a digital image corresponding to the image of the subject is generated. The digital image can be recorded on a recording medium such as an HDD (Hard Disk Drive), a memory card, an optical disk, or a magnetic tape. When the imaging device is a silver salt film camera, the image plane IP corresponds to the film plane.

  In the zoom lens of the present embodiment, the air gap is changed between the lens groups G1 to G4 during zooming from the wide-angle end to the telephoto end. That is, the air gap between the first lens group G1 and the second lens group G2, the air gap between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group. Each of the lens groups G1 to G4 is moved in the optical axis direction so that all the air gaps with G4 change.

  Specifically, at the time of zooming from the wide-angle end to the telephoto end, the first lens group G1 moves so as to draw a locus that is convex toward the image plane side, as indicated by an arrow a in FIG. The second lens group G2 and the third lens group G3 move from the image plane side to the object side, respectively, as indicated by arrows b and arrows c1 and c2 in FIG. The fourth lens group G4 moves from the image plane side to the object side as indicated by an arrow d in FIG.

  In the zoom lens of the present embodiment, the third lens group G3 moves from the object side to the image plane side when performing focusing (focusing) from an object at infinity to an object at a short distance. Note that an arrow c1 indicated by a solid line and an arrow c2 indicated by a broken line in FIG. 1 indicate image planes accompanying zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory for correcting the fluctuation is shown.

  In the zoom lens according to the present embodiment, as indicated by an arrow e in FIG. 1, the second c lens L6 is moved in a plane intersecting (preferably orthogonal) with the optical axis. As a result, the image formed on the image plane IP can be shifted in the direction perpendicular to the optical axis, and image blur caused by vibration such as camera shake can be optically corrected.

  As described above, in the four-unit zoom lens composed of the negative, positive, negative, and positive lens groups, the axial ray bundle is the largest on the object side of the second lens group G2, so that it is arranged on the most object side. In the second a lens L4, spherical aberration is likely to occur. Therefore, in order to reduce the influence of such aberration fluctuations, an image shake correction mechanism is provided that moves the second c lens L6 located closest to the image plane of the second lens group G2 in a direction substantially perpendicular to the optical axis. It is preferable to do. In this case, the aberration can be sufficiently removed by the two lenses L4 and L5 disposed on the object side of the second lens group G2, and the image blur is not affected by the various aberrations and is not affected by the second c lens L6. Correction can be performed.

In the zoom lens according to the present embodiment, the amount of movement in the optical axis direction of the second lens group G2 upon zooming from the wide-angle end to the telephoto end and M _2, during zooming from the wide angle end to the telephoto end the amount of movement in the optical axis direction of the fourth lens group G4 and M _4, a composite focal length of the fourth lens group G4 and f _4, a focal length of the entire system at the telephoto end when the f _t, the It is preferable to satisfy the following conditional expressions (1) and (2).
0.05 <M ₄ / M ₂ <1.0 (1)
0.8 <f ₄ / _ft <5.0 (2)

In the zoom lens of this embodiment, until the upper limit of the condition (1), the movement amount M ₄ of the fourth lens group G4 is longer than the movement amount M ₂ of the second lens group, the second lens group The amount of movement of the third lens group G3 disposed between G2 and the fourth lens group G4 is limited. In particular, when focusing is performed by moving the third lens group G3 in the optical axis direction, in order to ensure the amount of movement of the third lens group G3 when focusing on a close object at the telephoto end, Even at the wide-angle end, it is necessary to sufficiently widen the air gap between the third lens group G3 and the fourth lens group G3. In this case, the zoom lens cannot be reduced in size, which is not preferable.

On the other hand, in the zoom lens of this embodiment, until the lower limit of the condition (1), the movement amount M ₄ of the fourth lens group G4 becomes shorter than the moving amount M ₂ of the second lens group, lens When the mechanism for retracting the cylinder is constituted by a cam, a large difference occurs between the cam stroke of the second lens group G2 and the cam stroke of the fourth lens group G4. In this case, when the lens barrel is retracted for compact storage, the retracted thickness cannot be reduced, which is not preferable. Furthermore, if the amount of movement by which the fourth lens group G4 is moved to the object side at the telephoto end is short, the effective diameter of the fourth lens group G4 becomes large due to the influence of off-axis light beams in particular. In this case, it is not preferable because the weight increases and the cost increases as the fourth lens group G4 increases in size.

  In the zoom lens according to the present embodiment, if the positive refractive power of the fourth lens group G4 becomes weak until the upper limit value of the conditional expression (2) is exceeded, it is difficult to move the exit pupil away. In this case, having a strong gradient against incidence on the solid-state imaging device is not preferable because it leads to deterioration in image quality such as a decrease in the amount of incident light and erroneous incidence on the color filter.

  On the other hand, in the zoom lens according to the present embodiment, when the positive refractive power of the fourth lens group G4 increases until the lower limit value of the conditional expression (2) is not reached, it is difficult to correct spherical aberration at the telephoto end. Furthermore, it is not preferable because it is difficult to correct aberration variations well during zooming from the wide-angle end to the telephoto end.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expressions (1) ′ and (2) ′ are satisfied.
0.1 <M ₄ / M ₂ <0.8 (1) ′
0.9 <f ₄ / f _t <2.4 (2) ′

In the zoom lens according to the present embodiment, the refractive index with respect to the d-line (wavelength 587.56 nm) of the negative lens L7 constituting the third lens group G is nd _3, and the d-line of the positive lens L8 constituting the fourth lens group G4. It is preferable that the following conditional expressions (3) and (4) are satisfied, where nd ₄ is the refractive index with respect to.
1.65 <nd ₃ (3)
0.005 <nd ₃ −nd ₄ (4)

In the zoom lens of this embodiment, until the lower limit of the condition (3), lowering the refractive index nd ₃ of the negative lens L7 constituting the third lens group G3, to reduce the size of the entire lens system Becomes difficult. In particular, in order to increase the effect of telephoto arrangement at the telephoto end, it is necessary to increase the negative refractive power of the third lens group G3. However, when the refractive power of the lens material is low, the curvature of the lens surface becomes strong. As a result, coma aberration and field curvature deterioration due to decentration increase, which is not preferable. Further, if the curvature of the lens surface is increased, the thickness in the direction of the optical axis off the axis increases, which is disadvantageous for reducing the size and weight of the entire lens system.

In the zoom lens according to the present embodiment, when the refractive index nd ₄ of the positive lens L8 constituting the fourth lens group G4 is increased until the lower limit value of the conditional expression (4) is not reached, the fourth lens group G4 has the most image plane. Since the lens group is close to the lens group, the lens diameter of the positive lens L8 constituting the fourth lens group G4 is larger than that of the third lens group G4. End up. Further, since a material having a high refractive power has a high melting point and many hard materials, it is not preferable because it is relatively difficult to manufacture the positive lens L8 having a large lens diameter. Further, if the positive refractive power of the fourth lens group G4 is increased, the curvature of the lens surface becomes loose and the above-described ghost suppression effect is weakened, which is not preferable.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expressions (3) ′ and (4) ′ are satisfied.
1.70 <nd ₃ (3) ′
0.01 <nd ₃ −nd ₄ <0.2 (4) ′

In the zoom lens according to the present embodiment, the amount of movement in the optical axis direction of the second lens group G2 upon zooming from the wide-angle end to the telephoto end and M _2, during zooming from the wide angle end to the telephoto end the amount of movement in the optical axis direction of the third lens group G3 and M _3, the focal length of the third lens group G3 and f _3, the focal length of the entire system at the telephoto end when the f _t, the following It is preferable to satisfy the relationship of conditional expressions (5) and (6).
0.55 <M ₃ / M ₂ <1.0 (5)
0.1 <| f ₃ / f _t | <0.8 (6)

In the zoom lens of this embodiment, until the upper limit of the condition (5), the movement amount M ₃ of the third lens group G3 becomes longer than the movement amount M ₂ of the second lens group, a negative refractive power The third lens group G3 having a negative power decreases the zooming action of the second lens group G2 having a positive refractive power, which is the main zooming group. In this case, it is difficult to ensure a high zoom ratio, which is not preferable.

On the other hand, in the zoom lens of this embodiment, until the lower limit of the condition (5), the movement amount M ₃ of the third lens group G3 becomes shorter than the movement amount M ₂ of the second lens group, the telephoto end Therefore, the air gap between the second lens group G2 and the third lens group G3 becomes too large. In this case, the arrangement of the refracting power of the telephoto type constituted by the second lens group G2 and the third lens group G becomes too strong, and it becomes difficult to secure the necessary back focus, which is not preferable. Furthermore, when the mechanism for retracting the lens barrel is constituted by a cam, a large difference occurs between the cam stroke of the second lens group G2 and the cam stroke of the third lens group G3. In this case, when the lens barrel is retracted for compact storage, the retracted thickness cannot be reduced, which is not preferable.

  In the zoom lens according to the present embodiment, when the negative refractive power of the third lens group G3 becomes weak until the upper limit value of the conditional expression (6) is exceeded, the second lens group G2 and the third lens group G3 are configured. This is not preferable because the arrangement of the refractive power of the telephoto type is weakened and it is difficult to shorten the total lens length. Further, when focusing is performed by the third lens group G3, the movement amount of the third lens group G3 becomes long, and as a result, the entire lens length becomes long, which is not preferable.

  On the other hand, in the zoom lens according to the present embodiment, when the negative refractive power of the third lens group G3 increases until the lower limit of conditional expression (6) is not reached, deterioration of coma aberration and field curvature due to decentration increases. Therefore, it is not preferable.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expressions (5) ′ and (6) ′ are satisfied.
0.6 <M ₃ / M ₂ <1.0 (5) ′
0.25 <| f ₃ / f _t | <0.6 (6) ′

In the zoom lens according to the present embodiment, the focal length of the second lens group G2 and f _2, a focal length of the entire system at the telephoto end when a f _t, to satisfy the relation of the following conditional expressions (7) preferable.
_{0.1 <f 2 / f t <} 0.8 ... (7)

  In the zoom lens according to the present embodiment, when the positive refractive power of the second lens group G2 becomes weak until the upper limit value of the conditional expression (7) is exceeded, the second lens group G2 and the third lens group G3 are configured. This is not preferable because the arrangement of the refractive power of the telephoto type is weakened and it is difficult to shorten the total lens length.

  On the other hand, in the zoom lens according to the present embodiment, when the positive refractive power of the second lens group G2 becomes strong until the lower limit of the conditional expression (7) is not reached, it is difficult to correct spherical aberration particularly at the telephoto end. This is not preferable.

In the zoom lens according to the present embodiment, it is more preferable to satisfy the following conditional expression (7) ′.
_{0.25 <f 2 / f t <} 0.5 ... (7) '

In the zoom lens according to the present embodiment, the focal length of the 2b lens L5 and f _2b, the focal length of the second lens group G2 when the f _2, it is preferable to satisfy the relation of the following conditional expression (8) .
2.0 <f _2b / f ₂ <20.0 (8)

  In the zoom lens according to the present embodiment, if the positive refractive power of the second b lens L5 becomes weak until the upper limit value of the conditional expression (8) is exceeded, the positive refraction necessary for the entire lens constituting the second lens group G2 is reduced. In order to secure the force, it becomes necessary to increase the positive refractive power of the second a lens L4 in particular. In this case, the coma aberration and the field curvature deterioration due to the decentering of the second lens L4 become large, which is not preferable.

  On the other hand, in the zoom lens according to the present embodiment, if the positive refractive power of the second b lens L5 increases until it falls below the lower limit value of the conditional expression (8), it is difficult to correct spherical aberration with the second b lens L5. It is not preferable.

In the zoom lens according to the present embodiment, it is more preferable that the relationship of the following conditional expression (8) ′ is satisfied.
3.5 <f _2b / f ₂ <15.0 (8) ′

In the zoom lens according to the present embodiment, the focal length of the first lens group G1 and f _1, the focal length of the entire system at the telephoto end when a f _t, to satisfy the relation of the following conditional expression (9) preferable.
0.2 <| f ₁ / f _t | <0.8 (9)

  In the zoom lens of the present embodiment, when the negative refractive power of the first lens group G1 is weakened until the upper limit value of the conditional expression (9) is exceeded, the lenses of the lenses L1 to L3 constituting the first lens group G1. The diameter increases and the thickness also increases. In this case, the zoom lens of the present embodiment is undesirably large.

  On the other hand, in the zoom lens according to the present embodiment, when the negative refractive power of the first lens group G1 is increased until the lower limit value of the conditional expression (9) is not reached, correction of coma aberration and field curvature at the wide-angle end is performed. Is not preferable because it becomes difficult.

In the zoom lens according to the present embodiment, it is more preferable to satisfy the following conditional expression (9) ′.
0.4 <| f ₁ / f _t | <0.55 (9) ′

In the zoom lens of this embodiment, the paraxial curvature radius of the object side of the fourth lens group G4 and r _41, the focal length of the fourth lens group G4 when the f _4, relationship of the following conditional expressions (10) Is preferably satisfied.
-10.0 <r ₄₁ / f ₄ <0.0 (10)

In the zoom lens of this embodiment, until the upper limit of the condition (10), when the paraxial curvature radius r ₄₁ of the object side in the fourth lens group G4 is reduced, because the correct curvature of field becomes difficult It is not preferable.

On the other hand, in the zoom lens according to the present embodiment, when the paraxial radius of curvature r ₄₁ on the object side of the fourth lens group G4 increases until it falls below the lower limit value of the conditional expression (10), for example, the imaging surface of the solid-state imaging device or When a light beam reflected by an optical filter or the like enters the fourth lens group G4, it suppresses a ghost or the like generated when the light beam reflected by the fourth lens group G4 enters the imaging surface of the solid-state imaging device again. Is not preferable because it becomes difficult.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expression (10) ′ is satisfied.
−6.5 <r ₄₁ / f ₄ <−0.2 (10) ′

In the zoom lens of this embodiment, the paraxial curvature radius of the object side of the third lens group G3 and r _31, the paraxial curvature radius of the image side of the third lens group G3 when the r _32, the following conditions It is preferable to satisfy the relationship of Formula (11).
0.3 <(r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ ) <1.0 (11)

In the zoom lens of this embodiment, until the upper limit of the condition (11), the paraxial curvature radius r ₃₁ of the object side of the third lens group G3 increases, or the image plane of the third lens group G3 When the paraxial radius of curvature r ₃₂ on the side becomes small, the shape of the biconcave lens cannot be maintained, so that the negative refractive power of the third lens group G3 cannot be distributed to the object side and the image plane side, which is caused by decentration. This is not preferable because the curvature of field and the coma are greatly deteriorated.

On the other hand, in the zoom lens of this embodiment, until the lower limit of the condition (11), when the paraxial curvature radius r ₃₁ of the object side of the third lens group G3 decreases, before the third lens group G3 ( Since it is necessary to ensure a large air gap from the second c lens L6 arranged on the object side), it is not preferable from the viewpoint of miniaturization. Further, to below the lower limit of the condition (11), the image surface side of the paraxial curvature radius r ₃₂ of the third lens group G3 increases, diverging effect on the image plane side of the third lens group G3 is not This is not sufficient from the viewpoint of miniaturization because it is sufficient and the entire length needs to be increased when a desired image height is secured.

In the zoom lens according to the present embodiment, it is more preferable that the relationship of the following conditional expression (11) ′ is satisfied.
0.5 <(r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ ) <0.95 (11) ′

In the zoom lens according to the present embodiment, the focal length of the 2a lens L4 and f _2a, the focal length of the second lens group G2 when the f _2, it is preferable to satisfy the relation of the following conditional expression (12) .
0.8 <f _2a / f ₂ <1.8 (12)

  In the zoom lens of the present embodiment, if the positive refractive power of the second a lens L4 is weakened until the upper limit of the conditional expression (12) is exceeded, the convergence effect of the incident light beam is weakened, and the second a lens L4 This is not preferable because the diameter of the aperture stop SP arranged on the (image plane side) becomes large and it is difficult to reduce the size.

  On the other hand, in the zoom lens according to the present embodiment, if the positive refractive power of the second a lens L4 is increased until the lower limit of the conditional expression (12) is not reached, it is difficult to correct spherical aberration, which is not preferable.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expression (12) ′ is satisfied.
1.0 <f _2a / f ₂ <1.5 (12) ′

In the zoom lens according to the present embodiment, the focal length of the 2c lens L6 and f _2c, the focal length of the second lens group G2 when the f _2, it is preferable to satisfy the relation of the following conditional expression (13) .
2.5 <f _2c / f ₂ <5.0 (13)

  In the zoom lens according to the present embodiment, when the positive refractive power of the second c lens L6 is weakened until the upper limit value of the conditional expression (13) is exceeded, the amount of movement at the time of image blur correction increases, and the image blur correction mechanism operates. Since it enlarges, it is not preferable from a viewpoint of size reduction.

  On the other hand, in the zoom lens according to the present embodiment, when the positive refractive power of the second c lens L6 increases until it falls below the lower limit value of the conditional expression (13), decentration coma and curvature of field are corrected at the time of image blur correction. This is not preferable because it becomes difficult.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expression (13) ′ is satisfied.
3.0 <f _2c / f ₂ <4.2 (13) ′

In the zoom lens according to the present embodiment, when the paraxial curvature radius of the cemented surface of the cemented lens constituting the second b lens L5 is r _2b2 and the focal length of the second b lens L5 is f _2b , the following conditional expression (14 ) Is preferably satisfied.
0.0 <r _2b2 / f _2b <0.3 (14)

In the zoom lens of the present embodiment, it is difficult to correct spherical aberration when the paraxial radius of curvature _r2b2 of the cemented surface of the cemented lens constituting the second b lens L5 becomes smaller until the upper limit value of the conditional expression (14) is exceeded. Therefore, it is not preferable.

On the other hand, in the zoom lens of the present embodiment, when the paraxial radius of curvature _r2b2 of the cemented surface of the cemented lens constituting the second b lens L5 increases until the lower limit of the conditional expression (14) is not reached, the second a lens L4. Since it is difficult to increase the positive refractive power, it is not preferable from the viewpoint of miniaturization.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expression (14) ′ is satisfied.
0.05 <r _2b2 / f _2b <0.18 (14) ′

In the zoom lens of this embodiment, the paraxial curvature radius of the object side of the 2a lens L4 and r _2a1, the paraxial curvature radius of the image side of the 2a lens L4 when the r _2a2, the following conditional expression ( It is preferable to satisfy the relationship 15).
−1.0 <(r _2a1 + r _2a2 ) / (r _2a1 −r _2a2 ) <− 0.5 (15)

In the zoom lens of the present embodiment, when the paraxial curvature radius _r2a1 on the object side of the second a lens L4 increases until the upper limit value of the conditional expression (15) is exceeded, the converging action on the object side becomes insufficient, This is not preferable because it is difficult to reduce the size of the lens disposed behind (image plane side) the second a lens L4. Further, if the paraxial curvature radius _r2a2 on the image plane side of the second a lens L4 is reduced until the upper limit value of the conditional expression (15) is exceeded, it is difficult to correct curvature of field generated on the image plane side. It is not preferable.

On the other hand, in the zoom lens according to the present embodiment, the paraxial radius of curvature _r2a1 on the object side of the second a lens L4 is reduced until the lower limit of the conditional expression (15) is not reached, or the image plane of the second a lens L4. If the paraxial curvature radius r _2a2 on the side increases, the shape of the biconvex lens cannot be maintained, so that the positive refractive power of the second a lens L4 cannot be distributed to the object side and the image plane side, and the image due to decentration is lost. This is not preferable because the surface curvature and coma aberration are greatly deteriorated.

In the zoom lens according to the present embodiment, it is more preferable that the following conditional expression (15) ′ is satisfied.
−0.98 <(r _2a1 + r _2a2 ) / (r _2a1 −r _2a2 ) <− 0.7 (15) ′

  In the zoom lens according to the present embodiment that satisfies the above-described conditions, downsizing is realized while maintaining good optical performance during zooming, focusing, and image blur correction. That is, according to the present embodiment, while having a sufficient zoom ratio (for example, about 3 times), it is possible to satisfactorily correct the image plane variation caused by zooming and the aberration generated at the time of image blur correction. It is possible to provide a zoom lens and an imaging device that can achieve optical performance and can be further reduced in size and weight by shortening the total optical length.

Note that the present invention is not necessarily limited to the zoom lens of the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the zoom lens of the above embodiment, a lens group having a refractive power, a converter lens group, or the like can be disposed on the object side of the first lens group G1 as necessary.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

(Example 1)
The configuration of the zoom lens based on the design data of Example 1 is shown in FIG. 2, (W) shows the lens arrangement at the wide-angle end, (T) shows the lens arrangement at the intermediate focal position, and (T) shows the lens arrangement at the telephoto end.

  The zoom lens of Example 1 shown in FIG. 2 has a lens configuration similar to that of the zoom lens shown in FIG. 1 and is a lens for zooming and focusing and image blur correction similar to those of the zoom lens shown in FIG. Perform the action. Therefore, in FIG. 2, the same reference numerals are given to the same parts as the zoom lens shown in FIG. 1, and the movement locus of each lens is indicated by the same arrow.

  The design data of the zoom lens of Example 1 is as shown in Tables 1A to 1E below.

It should be noted that the surface number “i” (i represents a natural number) shown in Table 1A is the lens surface of the lens closest to the object side among the lenses constituting the zoom lens, and is on the image surface side. The number of the lens surface which increases sequentially as it goes is shown.
Also, among the lenses “GjRk (j represents a natural number, k represents 1 or 2)” shown in Table 1A, G represents a lens located closest to the object among the lenses constituting the zoom lens. As the second, the numbers of the lenses that sequentially increase toward the image plane side are shown. On the other hand, R indicates that the lens surface on the object side of each lens is 1, and the lens surface on the image plane side is 2. “Aperture” and “optical block (plane)” are also described together.
In addition, “r” shown in Table 1A is a curvature radius [mm] of the lens surface corresponding to each surface number (however, a surface where the value of R is ∞ indicates that the surface is a plane). Is shown.
Further, “d” shown in Table 1A indicates the axial upper surface distance [mm] between the i-th lens surface and the i + 1-th lens surface from the object side, and when variable, the wide-angle end, the intermediate focal position, The shaft upper surface distance [mm] at the telephoto end is shown separately.
“Nd” shown in Table 1A indicates the refractive index of each lens.
In addition, “νd” shown in Table 1A indicates the Abbe number of each lens.

  Table 1B shows the zoom ratio, “focal length” [mm], “F number (Fno)” and “half angle of view (ω)” [° at the wide-angle end, intermediate focal position, and telephoto end. ], “Image height” [mm], “lens total length” [mm], and “back focus (BF)” [mm]. The total lens length is a value obtained by adding back focus (BF) to the distance from the lens front surface to the lens final surface. Further, the back focus (BF) is a value obtained by converting the distance from the last lens surface to the paraxial image surface into air.

Table 1C shows the surface numbers of aspherical lenses and their aspherical coefficients. The aspherical surface can be expressed by the following aspherical formula X with the displacement in the optical axis direction at the position of the height H from the optical axis as a reference. “R” represents a radius of curvature, “K” represents a conic constant, and “A ₄ , A ₆ , A ₈ , A ₁₀ ” represents an aspheric coefficient. Note that the notation “E ± m” (m represents an integer) in the numerical value of the aspheric coefficient means “× 10 ^{± m} ”.

Table 1D includes (1) “M ₄ / M ₂ ”, (2) “f ₄ / _ft ”, (3) “nd ₃ ”, (4) “nd ₃ -nd ₄ ”, (5) “ M ₃ / M ₂ ”, (6)“ | f ₃ / f _t | ”, (7)“ f ₂ / f _t ”, (8)“ f _2b / f ₂ ”, (9)“ | f ₁ / f _t | ”, (10)“ r ₄₁ / f ₄ ”, (11)“ (r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ ) ”, (12)“ f _2a / f ₂ ”, (13) _"f 2c / _{f 2"} shows (14) _"r 2b2 / _{f 2"} (15) _{"(r 2a1 + r 2a2) /} (r 2a1 -r 2a2) " the conditional expressions.

  Table 1E shows the amount of movement [mm] in the direction perpendicular to the optical axis of the second c lens at the time of image blur correction at the wide-angle end, and the optical axis of the second c lens at the time of image blur correction at the telephoto end. The amount of movement [mm] in any direction.

  FIG. 3 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 1 configured as described above.

In FIG. 3, (W) is a longitudinal aberration diagram at the wide-angle end, (M) is a longitudinal aberration diagram at the intermediate focal position, and (T) is a longitudinal aberration diagram at the telephoto end. Each longitudinal aberration diagram shows a spherical aberration diagram [mm], an astigmatism diagram [mm], and a distortion aberration diagram [%] in order from the left side.
In the spherical aberration diagram, the vertical axis represents the F number (Fno), the spherical aberration at the d-line (wavelength 587.56 nm) is indicated by a solid line, and the spherical aberration at the g-line (wavelength 435.835 nm) is indicated by a one-dot chain line.
In the astigmatism diagram, the vertical axis represents the image height (y), and shows astigmatism with respect to sagittal ray ΔS (solid line) and median ray ΔM (broken line) at each wavelength.
In the distortion diagram, the vertical axis represents the image height (y), and the distortion (distortion) at the d-line (wavelength 587.56 nm) is indicated by a solid line.

  FIGS. 4A and 4B are lateral aberration diagrams at the infinity in-focus position before decentering (normal time) and after decentering (image blur correction) of the zoom lens of Example 1. FIGS. 4A shows a lateral aberration diagram at the wide-angle end in the zoom lens of Example 1. FIG. 4B is a lateral aberration diagram at the telephoto end in the zoom lens of Example 1. FIG.

  4A and 4B, (A) is a lateral aberration diagram before decentration at an image height of 10 mm (corresponding to about 70% of the maximum image height), and (B) is an image height of 0 mm (optical axis center position). The lateral aberration before decentration, (C) is the lateral aberration before decentration at the image height of −10 mm (equivalent to about −70% of the maximum image height), and (D) is the image height at 10 mm (about 70 of the maximum image height). % Equivalent) lateral aberration after decentering, (E) lateral aberration after decentering at an image height of 0 mm (optical axis center position), and (F) an image height of −10 mm (approximately −70 of the maximum image height). % Equivalent) is a lateral aberration diagram after decentration. In each lateral aberration diagram, the horizontal axis represents the distance from the principal ray on the stop position, the solid line represents the d-line characteristic, and the broken line represents the g-line characteristic.

  The zoom lens of Example 1 satisfies the conditions of the present invention as shown in Tables 1A to 1E. In the zoom lens of Example 1, it can be seen that each aberration is well corrected as shown in FIG. 3 and FIGS. 4A and 4B.

  Specifically, the image decentering amount when the zoom lens is tilted by 0.3 ° at the wide-angle end and the telephoto end at the infinity in-focus position is as described above in the direction in which the second c lens L6 is perpendicular to the optical axis. It is equal to the amount of image eccentricity when moving in parallel by the value. As can be seen from the respective lateral aberration diagrams, the symmetry of the lateral aberration at the center position of the optical axis is good. Further, comparing the lateral aberration diagram at the image height position of 10 mm and the lateral aberration diagram at the position of −10 mm before and after decentering, it can be seen that the degree of curvature is small and the inclination of the aberration curve is almost equal. As a result, it can be seen that decentration coma and field curvature due to decentration are suppressed to a small level, and that sufficient imaging performance is obtained even in an image shake correction state.

(Example 2)
The configuration of the zoom lens based on the design data of Example 2 is shown in FIG. The zoom lens of Example 2 shown in FIG. 5 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image blur correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 5, the same reference numerals are given to the same parts as those of the zoom lens shown in FIG. 1, and the movement trajectory of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 2 is as shown in Tables 2A to 2E below. In addition, about the description method of Table 2A-Table 2E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 6 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 2 configured as described above. 7A and 7B show lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 2. FIG. In addition, about the description method of FIG.6, FIG.7A and FIG.7B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 2 satisfies the above-described conditions of the present invention as shown in Tables 2A to 2E. In the zoom lens of Example 2, it can be seen that each aberration is well corrected as shown in FIGS. 6, 7A and 7B.

(Example 3)
The configuration of the zoom lens based on the design data of Example 3 is shown in FIG. The zoom lens of Example 3 shown in FIG. 8 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image shake correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 8, the same reference numerals are given to the same parts as the zoom lens shown in FIG. 1, and the movement locus of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 3 is as shown in Tables 3A to 3E below. In addition, about the description method of Table 3A-Table 3E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 9 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 3 configured as described above. 10A and 10B show lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 3. FIG. In addition, about the description method of FIG.9, FIG.10A and FIG.10B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 3 satisfies the above-described conditions of the present invention as shown in Tables 3A to 3E. As for the zoom lens of Example 3, it can be seen that each aberration is corrected well as shown in FIGS. 9, 10A and 10B.

Example 4
The configuration of the zoom lens based on the design data of Example 4 is shown in FIG. The zoom lens of Example 4 shown in FIG. 11 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image shake correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 11, the same reference numerals are given to the same parts as the zoom lens shown in FIG. 1, and the movement locus of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 4 is as shown in Tables 4A to 4E below. In addition, about the description method of Table 4A-Table 4E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 12 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 4 configured as described above. 13A and 13B show lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 4. FIG. In addition, about the description method of FIG.12, FIG.13A and FIG.13B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 4 satisfies the above-described conditions of the present invention as shown in Tables 4A to 4E. In the zoom lens of Example 4, it can be seen that each aberration is well corrected as shown in FIGS. 12, 13A, and 13B.

(Example 5)
The configuration of the zoom lens based on the design data of Example 5 is shown in FIG. The zoom lens of Example 5 shown in FIG. 14 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image shake correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 14, the same reference numerals are given to the same parts as the zoom lens shown in FIG. 1, and the movement locus of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 5 is as shown in Tables 5A to 5E below. In addition, about the description method of Table 5A-Table 5E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 15 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 5 configured as described above. 16A and 16B show lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 5. FIG. In addition, about the description method of FIG.15, FIG.16A and FIG.16B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 5 satisfies the above-described conditions of the present invention as shown in Tables 5A to 5E. In the zoom lens of Example 5, it can be seen that each aberration is well corrected as shown in FIGS. 15, 16A, and 16B.

(Example 6)
The configuration of the zoom lens based on the design data of Example 6 is shown in FIG. The zoom lens of Example 6 shown in FIG. 17 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image blur correction as those of the zoom lens shown in FIG. The lens operation is performed. Accordingly, in FIG. 17, the same parts as those of the zoom lens shown in FIG. 1 are denoted by the same reference numerals, and the movement trajectory of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 6 is as shown in Tables 6A to 6E below. In addition, about the description method of Table 6A-Table 6E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 18 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 6 configured as described above. 19A and 19B show lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 6. FIG. In addition, about the description method of FIG.18, FIG.19A and FIG.19B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 6 satisfies the conditions of the present invention as shown in Tables 6A to 6E. In the zoom lens of Example 6, it can be seen that each aberration is well corrected as shown in FIGS. 18, 19A and 19B.

(Example 7)
The configuration of the zoom lens based on the design data of Example 7 is shown in FIG. The zoom lens of Example 7 shown in FIG. 20 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image shake correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 20, the same reference numerals are given to the same parts as the zoom lens shown in FIG. 1, and the movement trajectory of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 7 is as shown in Tables 7A to 7E below. In addition, about the description method of Table 7A-Table 7E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 21 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 7 configured as described above. 22A and 22B are lateral aberration diagrams of the zoom lens of Example 7 at the wide-angle end and the telephoto end. In addition, about the description method of FIG.21, FIG.22A and FIG.22B, it is the same as that of the case shown to FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 7 satisfies the conditions of the present invention as shown in Tables 7A to 7E. And as for the zoom lens of Example 7, as shown in FIG. 21, FIG. 22A, and FIG. 22B, it turns out that each aberration is correct | amended favorably.

(Example 8)
The configuration of the zoom lens based on the design data of Example 8 is shown in FIG. The zoom lens of Example 8 shown in FIG. 23 has the same lens configuration as that of the zoom lens shown in FIG. 1, and has the same zooming and focusing and image shake correction as those of the zoom lens shown in FIG. The lens operation is performed. Therefore, in FIG. 23, parts equivalent to those of the zoom lens shown in FIG. 1 are given the same reference numerals, and the movement trajectory of each lens is indicated by the same arrow.

  The design data of the zoom lens shown in Example 8 is as shown in Tables 8A to 8E below. In addition, about the description method of Table 8A-Table 8E, it is the same as that of the case of Table 1A-Table 1E.

  FIG. 24 shows longitudinal aberration diagrams (spherical aberration diagram, astigmatism diagram, distortion aberration diagram) in the zoom lens of Example 8 configured as described above. Also, lateral aberration diagrams at the wide-angle end and the telephoto end in the zoom lens of Example 8 are shown in FIGS. 25A and 25B. In addition, about the description method of FIG.24, FIG.25A and FIG.25B, it is the same as that of the case shown in FIG.3, FIG.4A and FIG.4B.

  The zoom lens of Example 8 satisfies the above-described conditions of the present invention as shown in Tables 8A to 8E. In the zoom lens of Example 8, it can be seen that each aberration is well corrected as shown in FIGS. 24, 25A and 25B.

  G1 ... 1st lens group L1-L3 ... Lens which comprises 1st lens group G2 ... 2nd lens group L4 ... 2a lens L5 ... 2b lens L5a, L5b ... Lens which comprises 2b lens L6 ... 2c lens G3 ... Third lens group L7 ... Lens constituting the third lens group G4 ... Fourth lens group L8 ... Lens constituting the fourth lens group SP ... Aperture stop G ... Optical block IP ... Image plane

Claims (24)

In order from the object side, a first lens group having a negative refractive power as a whole, a second lens group having a positive refractive power as a whole, a third lens group having a negative refractive power as a whole, and a positive as a whole A zoom lens that changes the air spacing between the lens groups upon zooming from the wide-angle end to the telephoto end.
The first lens group has at least two negative lenses and one positive lens,
The second lens group has a function of correcting image blur by moving at least a part of the lens in a plane intersecting the optical axis;
The zoom lens according to claim 3, wherein the third lens group includes one negative lens. The amount of movement in the optical axis direction of the second lens group upon zooming from the wide-angle end to the telephoto end and M _2, the light of the fourth lens group during zooming from the wide angle end to the telephoto end the amount of movement in the axial direction and M _4, a composite focal length of the fourth lens group and f _4, a focal length of the entire system at the telephoto end when a f _t,
0.05 <M ₄ / M ₂ <1.0,
_{0.8 <f 4 / f t <} 5.0
The zoom lens according to claim 1, wherein the following relationship is satisfied.   3. The image blur is corrected by moving a lens located closest to the image plane side in a plane intersecting the optical axis among a plurality of lenses constituting the second lens group. Zoom lens described in 1.   The image blur is corrected by moving a lens located third from the object side in a plane intersecting the optical axis among the plurality of lenses constituting the second lens group. The zoom lens according to 2.   5. The negative lens constituting the third lens group is a biconcave lens in which both surfaces thereof are concave, and at least one surface is an aspherical surface. Zoom lens described in 1. The fourth lens group is composed of one positive lens,
6. The positive lens constituting the fourth lens group is a meniscus lens having a convex image surface side, and at least one surface is aspherical. The zoom lens according to item. The paraxial radius of curvature of the object side of the fourth lens group and r _41, the focal length of the fourth lens group when the f _4,
-10.0 <r ₄₁ / f ₄ <0.0
The zoom lens according to claim 6, wherein the following relationship is satisfied. When the refractive index for the d-line of the negative lens constituting the third lens group is nd _3, and the refractive index for the d-line of the positive lens constituting the fourth lens group is nd ₄ ,
1.65 <nd ₃ ,
0.005 <nd ₃ -nd ₄
The zoom lens according to claim 6, wherein the following relationship is satisfied. The amount of movement in the optical axis direction of the second lens group upon zooming from the wide-angle end to the telephoto end and M _2, the light of the third lens group during zooming to the telephoto end from the wide-angle end the amount of movement in the axial direction and M _3, the focal length of the third lens group and f _3, the focal length of the entire system at the telephoto end when a f _t,
0.55 <M ₃ / M ₂ <1.0,
0.1 <| f ₃ / f _t | <0.8
The zoom lens according to claim 1, wherein the following relationship is satisfied. When the paraxial curvature radius on the object side of the third lens group is r ₃₁ and the paraxial curvature radius on the image plane side of the third lens group is r ₃₂ ,
0.3 <(r ₃₁ + r ₃₂ ) / (r ₃₁ −r ₃₂ ) <1.0
The zoom lens according to claim 9, wherein the following relationship is satisfied.   The second lens group includes, in order from the object side, a second lens having positive refractive power, a second lens having positive refractive power, and a second lens having positive refractive power. The zoom lens according to any one of claims 1 to 10. The focal length of the second lens group and f _2, a focal length of the entire system at the telephoto end when a f _{t,
0.1 <f 2 / f t <} 0.8
The zoom lens according to claim 11, wherein the following relationship is satisfied. The second a lens is a biconvex lens whose both surfaces are convex, and at least one surface is an aspheric surface,
The zoom lens according to claim 11 or 12, wherein the second b lens is a cemented lens in which a negative lens and a positive lens are cemented in order from the object side. The focal length of the 2b lens and f _2b, the focal length of the second lens group when the f _2,
2.0 <f _2b / f ₂ <20.0
The zoom lens according to claim 13, wherein the following relationship is satisfied. The focal length of the 2a lens and f _2a, the focal length of the second lens group when the f _2,
0.8 <f _2a / f ₂ <1.8
The zoom lens according to claim 13, wherein the following relationship is satisfied. The focal length of the third 2c lens and f _2c, the focal length of the second lens group when the f _2,
2.5 <f _2c / f ₂ <5.0
The zoom lens according to claim 13, wherein the following relationship is satisfied. When the paraxial radius of curvature of the cemented surface of the cemented lens constituting the second b lens is r _2b2 and the focal length of the second b lens is f _2b ,
0.0 <r _2b2 / f _2b <0.3
The zoom lens according to claim 13, wherein the following relationship is satisfied. When the paraxial curvature radius on the object side of the 2a lens is r _2a1 and the paraxial curvature radius on the image plane side of the 2a lens is r _2a2 ,
−1.0 <(r _2a1 + r _2a2 ) / (r _2a1 −r _2a2 ) <− 0.5
The zoom lens according to claim 13, wherein the following relationship is satisfied.   The said 2b lens is a cemented lens which joined the negative lens which the object side becomes convex, and the positive lens whose both surfaces become convex, The Claim 13-18 characterized by the above-mentioned. Zoom lens.   The zoom lens according to claim 11, wherein the second c lens is a positive meniscus lens having a convex surface on the object side.   The zoom lens according to any one of claims 11 to 20, wherein a stop is disposed between the second a lens and the second b lens.   The first lens group includes, in order from the object side, a negative lens having a convex surface on the object side, a negative lens having concave surfaces on both sides, and a positive lens having a convex surface on the object side, and The zoom lens according to any one of claims 1 to 21, wherein at least one surface of any lens constituting the first lens group is an aspherical surface. The focal length of the first lens group and f _1, the focal length of the entire system at the telephoto end when a f _t,
0.2 <| f ₁ / f _t | <0.8
The zoom lens according to claim 22, wherein the following relationship is satisfied. The zoom lens according to any one of claims 1 to 23;
An image pickup apparatus comprising: a solid-state image pickup device that picks up an image formed by the zoom lens.

Images