Zoom lens and image capturing device

Abstract

To provide a compact, light-weight zoom lens which offers high optical performance, and to provide an image capturing device.SOLUTION: In order to clear the above problem, a zoom lens of the present invention comprises a positive first lens group G1 and a rear group comprising at least one positive lens group Gp (G4, G5) in order from the object side, and is configured to change air gap distances between adjacent lens groups for zooming. The first lens group G1 has a positive lens L1p1 (L2), where the first lens group G1 may comprise two or less positive lenses, and the lens group Gp (G4) has a lens Lpn (L12) having negative refractive power. The zoom lens satisfies predetermined conditional expressions. An image capturing device of the present invention is equipped with such zoom lens.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 an imaging optical system of an imaging device using a solid-state imaging element or the like. [Background technology]

[0002] In recent years, imaging devices using solid-state imaging elements, such as digital still cameras and digital video cameras, have become widespread. Accordingly, the optical systems of these imaging devices have become more compact and more powerful, and compact imaging device systems have become widespread. Furthermore, there is a particularly strong demand for compactness as well as high performance of the optical system in telephoto zoom lenses with long focal lengths.

[0003] Therefore, Patent Document 1 proposes a zoom lens with a zoom ratio of about 4, a focal length at the telephoto end of about 600 mm when converted into a 35 mm format, and an F-number of about 6.3. This zoom lens achieves a telephoto effect, i.e., a longer focal length than conventional lenses, while also being compact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-126850 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the zoom lens disclosed in Patent Document 1 realizes high optical performance by forming the first lens group using a positive lens made of a glass material having anomalous dispersion. However, the zoom lens disclosed in Patent Document 1 is not sufficient in terms of reducing the size and weight of the entire zoom lens unit. In a telephoto zoom lens, the diameter of the lenses forming the first lens group is large, and the positive lenses are thick. In addition, glass materials having anomalous dispersion are expensive and have a large specific gravity. Therefore, if a positive lens having anomalous dispersion is arranged in the first lens group, the cost increases and the lens becomes heavy. Furthermore, if the first lens group becomes heavy, the driving mechanism for moving the first lens group along the optical axis during magnification change also becomes large, and the entire zoom lens unit also becomes large and heavy.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a zoom lens and an image pickup apparatus that are small, lightweight, and have high optical performance. [Means for solving the problem]

[0007] In order to achieve the above object, a zoom lens according to the present invention is composed of, in order from the object side, a first lens group having positive refractive power and a rear group including at least one lens group Gp having positive refractive power, and changes the air space between adjacent lens groups to vary the magnification, the first lens group has a lens L1p1 having positive refractive power, and the number of lenses having positive refractive power included in the first lens group is two or less, and the lens group Gp has a lens Lpn having negative refractive power, the rear group has a lens having a positive refractive power located closest to the object, a focus group which is one of the lens groups constituting the rear group or a part thereof; the rear group includes at least one lens Lnr having negative refractive power, the rear group has a vibration reduction group that corrects image blur by moving in a direction perpendicular to the optical axis, The number of focus groups is only one, It is characterized in that the following conditional expression is satisfied. 3.50 < ft / fnot / Y < 9.00 (1) 63.0 < νdL1p1 < 76.0 (2) 38.0 < νdLpn < 65.0 (3) 1.91082 ≦ NdLnr < 2.20 (10) 1.80 < BFw / (fw×tanωw) < 3.20 ····(11) however, ft: focal length of the zoom lens at the telephoto end fnot: F-number of the zoom lens at the telephoto end Y: Maximum image height of the zoom lens νdL1p1: Abbe number at the d line of the lens L1p1 νdLpn: Abbe number at d line of the lens Lpn NdLnr: refractive index at d line of the lens Lnr BFw: The air equivalent length of the zoom lens at the wide-angle end from the lens surface closest to the image plane to the image plane fw: focal length of the zoom lens at the wide-angle end ωw: Half angle of view of the most off-axis chief ray of the zoom lens when focused at infinity at the wide-angle end In order to solve the above problems, a zoom lens according to the present invention is composed of, in order from the object side, a first lens group having positive refractive power and a rear group including at least one lens group Gp having positive refractive power, and the magnification is changed by changing the air space between adjacent lens groups, the first lens group includes a lens L1p1 having positive refractive power, and the first lens group includes two or less lenses having positive refractive power, the lens group Gp is ​​disposed closest to the object side among the lens groups having positive refractive power included in the rear group, The lens group Gp includes a lens Lpn having a negative refractive power, the rear group has a lens having a positive refractive power located closest to the object, the rear group includes at least one lens Lnr having negative refractive power, the rear group has a vibration reduction group that corrects image blur by moving in a direction perpendicular to the optical axis, It is characterized in that the following conditional expression is satisfied. 63.0 < νdL1p1 < 76.0 (2) 38.0 < νdLpn < 65.0 (3) 1.91082 ≦ NdLnr < 2.20 (10) however, ft: focal length of the zoom lens at the telephoto end fnot: F-number of the zoom lens at the telephoto end Y: Maximum image height of the zoom lens νdL1p1: Abbe number at the d line of the lens L1p1 νdLpn: Abbe number at d line of the lens Lpn NdLnr: refractive index at d line of the lens Lnr

[0008] In order to solve the above problem, the imaging device of the present invention is characterized in that it includes the above zoom lens and an imaging element on the image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal. Effect of the Invention

[0009] According to the present invention, it is possible to provide a zoom lens and an imaging device that are small, lightweight, and have high optical performance. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention at the wide-angle end when focused on infinity. [Diagram 2] 4A to 4C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 1 when focused on an object at infinity at the wide-angle end. [Diagram 3] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration when the zoom lens of Example 1 is in an intermediate focal length state and focused on an object at infinity. [Figure 4]3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 1 when focused on an object at infinity at the telephoto end. [Diagram 5] FIG. 11 is a cross-sectional view of a zoom lens according to a second embodiment of the present invention at the wide-angle end when focused on infinity. [Figure 6] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 2 when focused on an object at infinity at the wide-angle end. [Figure 7] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration when the zoom lens of Example 2 is in an intermediate focal length state and focused on an object at infinity. [Figure 8] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 2 when focused on an object at infinity at the telephoto end. [Figure 9] FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention at the wide-angle end when focused on infinity. [Figure 10] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 3 when focused on an object at infinity at the wide-angle end. [Figure 11] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 3 when focused on an object at infinity in an intermediate focal length state. [Figure 12] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 3 when focused on an object at infinity at the telephoto end. [Figure 13] FIG. 11 is a cross-sectional view of a zoom lens according to a fourth embodiment of the present invention at the wide-angle end when focused on infinity. [Figure 14] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity at the wide-angle end. [Figure 15] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity in an intermediate focal length state. [Figure 16] 11A to 11C are diagrams illustrating spherical aberration, astigmatism, and distortion aberration of the zoom lens of Example 4 when focused on an object at infinity at the telephoto end. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment 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.

[0012] 1. Zoom Lens 1-1.Optical structure of zoom lenses The zoom lens of the present embodiment is composed of, in order from the object side, a first lens group having a positive refractive power and a rear group. By adopting a power arrangement in which a positive refractive power is arranged at the most object side of the zoom lens, the maximum height of the axial light beam can be suppressed, and thus the zoom lens can be easily made compact in the radial direction. In particular, since the lenses constituting the first lens group can be easily made compact in the radial direction, the volume of the lenses constituting the first lens group can be reduced. In a telephoto zoom lens with a long focal length, the diameter of the lenses constituting the first lens group is larger than the diameter of the lenses constituting the other lens groups. By making the first lens group compact in the radial direction, the effect of making the zoom lens compact and lightweight as a whole is increased. In particular, when this power arrangement is adopted in a zoom lens configured so that the entrance pupil diameter of the zoom lens at the telephoto end is larger than 80 mm while including a focal length longer than 100 mm in 35 mm format in the zoom range, the effect is remarkable.

[0013] Furthermore, in this zoom lens, the diameter of the light beam incident on the rear group is smaller than that of the light beam incident on the first lens group. Therefore, when the focus group or the vibration-proof group is arranged in the rear group, the focus group or the vibration-proof group can be made smaller and lighter than when the focus group or the vibration-proof group is arranged in the first lens group. The optical configuration of each lens group will be described below. Note that the zoom lens may be substantially composed of the first lens group and the rear group. That is, in addition to the lens groups described below, optical elements that have no refractive power or have very small refractive power may be arranged. Examples of such optical elements include various filters such as a protective filter for protecting the lens from dirt and scratches, an ND filter used to reduce the amount of incident light, and a PL filter for adjusting color.

[0014] (1) First lens group In the zoom lens, the first lens group is disposed closest to the object side. There are no particular limitations on the specific lens configuration of the first lens group, so long as the first lens group has positive refractive power as a whole.

[0015] Since the first lens group has a positive refractive power as a whole, the first lens group has at least one lens having a positive refractive power. That is, the lens having a positive refractive power included in the first lens group may be only this lens L1p1. However, in order to satisfactorily correct chromatic aberration and spherical aberration at the telephoto end, it is preferable that the first lens group includes a lens L1p2 having a positive refractive power in addition to the lens L1p1. By increasing the number of lenses having a positive refractive power included in the first lens group, it is possible to obtain a zoom lens with high optical performance by suppressing the occurrence of spherical aberration and the like by adjusting the shape of each surface while arranging a strong positive refractive power in the first lens group. However, the first lens group is composed of a lens with the largest diameter in the zoom lens. Therefore, if the number of lenses constituting the first lens group increases, the zoom lens becomes heavy. Therefore, from the viewpoint of improving the performance of the zoom lens while suppressing an increase in the weight of the zoom lens, the number of lenses having positive refractive power included in the first lens group in the zoom lens is set to two or less.

[0016] Furthermore, it is preferable for the first lens group to have at least one lens L1n having negative refractive power in order to correct chromatic aberration and improve image surface quality.

[0017] For these reasons, it is more preferable to configure the first lens group with a total of three lenses, namely, one lens L1n having negative refractive power and two lenses (lenses L1p1 and L1p2) having positive refractive power, in order to realize a high-performance zoom lens while suppressing increases in cost and weight.

[0018] Furthermore, when the first lens group includes a lens L1n having a negative refractive power, it is preferable that the lens L1n is cemented with the lens L1p1 or lens L1p2. By cementing the lens L1n having a negative refractive power and a lens having a positive refractive power (lens L1p1 or lens L1p2), various manufacturing errors such as decentering errors and errors in the air gap between single lenses can be reduced compared to the case where these lenses are arranged with an air gap between them. Therefore, it is possible to reduce the deterioration of optical performance caused by manufacturing errors, and to reduce the variation in performance between products. Therefore, by cementing the lens L1n having a negative refractive power and a lens having a positive refractive power (lens L1p1 or lens L1p2), it is possible to manufacture a zoom lens with high optical performance with a high yield.

[0019] However, if there is a difference in the linear expansion coefficient of the glass materials of the lenses to be cemented together, the manner of shape change due to expansion or contraction of the glass materials caused by changes in the ambient temperature will differ, and stress will be applied to the cemented surface. The larger the diameter of the lenses constituting the cemented lens, the greater the stress applied to this cemented surface due to the difference in the linear expansion coefficient of the glass materials, and the greater the defects such as cracking or breaking of the cemented lens will occur at the cemented surface. If the difference in the linear expansion coefficients of the lenses constituting the cemented lens is large, the larger the diameter of the cemented lens, the more likely this phenomenon will occur. That is, since the diameter of the lenses constituting the first lens group is larger than that of the other lens groups, the cemented lens arranged in the first lens group is more likely to cause this phenomenon than the other lens groups. Therefore, when the rate of change in the length of a sample when the temperature is changed under a constant pressure (1 atm) is defined as the linear expansion coefficient, and the average rate of change in the length of the sample in the temperature range of -30°C to 70°C is defined as the average linear expansion coefficient α, it is preferable that the difference between the average linear expansion coefficient α1p of the lens having positive refractive power constituting the cemented lens in the first lens group and the average linear expansion coefficient α1n of the lens L1n having negative refractive power is small. More specifically, 0<α1p-α1n<50×10 -7 / ° C. When this condition is satisfied, when the lens L1n having negative refractive power arranged in the first lens group is cemented to the lens L1p1 or lens L1p2 having positive refractive power, cracking of the cemented lens due to changes in the atmospheric temperature can be suppressed, which is preferable.

[0020] Furthermore, from the viewpoint of chromatic aberration correction, it is preferable that the Abbe number at the d-line of the lens L1n having negative refractive power included in the first lens group is smaller than 45, and that the Abbe number at the d-line of at least one of the lenses (lens L1p1 or lens L1p2) among the lenses having positive refractive power included in the first lens group is larger than 65. When these conditions are satisfied, it is possible to realize a zoom lens in which chromatic aberration is well corrected even at the telephoto end.

[0021] In addition, it is preferable in terms of chromatic aberration correction that at least one of the lenses having positive refractive power included in the first lens group (lens L1p1 or lens L1p2) is made of a glass material having high anomalous dispersion. In particular, it is preferable that at least one of the lenses having positive refractive power included in the first lens group (lens L1p1 or lens L1p2) has an anomalous dispersion (ΔPgF) larger than 0.015, more preferably larger than 0.019, and even more preferably larger than 0.025. The anomalous dispersion (ΔPgF) refers to the deviation of the partial dispersion ratio from a reference line when a straight line passing through the partial dispersion ratios and the coordinates of νd of C7 (partial dispersion ratio: 0.5393, νd: 60.49) and F2 (partial dispersion ratio: 0.5829, νd: 36.30) is used as the reference line.

[0022] Since glass materials with high anomalous dispersion have a relatively high specific gravity, when the first lens group includes two lenses having positive refractive power (lens L1p1, lens L1p2), it is preferable in terms of achieving high performance and lightweight of the zoom lens that one of the lenses is made of a glass material with high anomalous dispersion and the other lens is made of a glass material with a large Abbe number and a low specific gravity.

[0023] (2) Rear group The rear group is a collective term for a plurality of lens groups arranged closer to the image side than the first lens group. The rear group includes a lens group Gp having a positive refractive power. The rear group is not particularly limited to other lens group configurations as long as it includes a lens group Gp having a positive refractive power. For example, the rear group may have two or more lens groups having a positive refractive power, or may have one or more lens groups having a negative refractive power. In addition, if the refractive power of the rear group is negative overall at the telephoto end, the refractive power arrangement has a strong telephoto tendency. Therefore, the effect of shortening the optical total length of the zoom lens at the telephoto end compared to the focal length is large, which is preferable in terms of miniaturizing the zoom lens. However, the refractive power of the entire rear group at the telephoto end may be negative or positive, and the sign of the refractive power of the entire rear group is not particularly limited. In addition, a strong telephoto tendency means that the telephoto ratio (L / f, L means the optical total length, and f means the focal length) is small.

[0024] (a) Object-side group Rfn and image-side group Rrp It is preferable that the rear group comprises an object-side group Rfn including at least one lens group and having negative refractive power overall on the object side of the largest air space at the wide-angle end, and an image-side group Rrp including at least one lens group and having positive refractive power overall on the image side of the largest air space at the wide-angle end. By adopting a refractive power arrangement in which the object-side group Rfn having negative refractive power overall is arranged on the object side of the largest air space at the wide-angle end in the rear group, and the image-side group Rrp having positive refractive power overall is arranged on the image side thereof, a large composite lateral magnification by the object-side group Rfn can be ensured, which is effective in lengthening the focal length of the zoom lens at the telephoto end.

[0025] In this case, the lens group configuration of the object side group Rfn in the rear group is not particularly limited. The object side group Rfn may have, for example, two or more lens groups having negative refractive power, or one or more lens groups having positive refractive power. The lens group configuration of the image side group Rrp in the rear group is also not particularly limited, but it is preferable that it includes at least one lens group having positive refractive power.

[0026] (b) Lens group Gp The arrangement of the lens group Gp having positive refractive power within the rear group is not particularly limited as long as it is arranged within the rear group. For example, when the rear group is composed of the object side group Rfn having negative refractive power and the image side group Rrp having positive refractive power, it is preferable that the lens group Gp having positive refractive power is arranged in the image side group Rrp.

[0027] Moreover, it is preferable that the lens group Gp having positive refractive power has at least one lens Lpn having negative refractive power. If the lenses constituting the first lens group are made of a glass material with a low specific gravity in order to reduce the weight of the first lens group, chromatic aberration cannot be sufficiently corrected in the first lens group. Therefore, it is necessary to correct the chromatic aberration generated in the first lens group in the rear group. Therefore, by arranging the lens Lpn having negative refractive power in the lens group Gp having positive refractive power arranged in the rear group, the axial chromatic aberration can be well corrected, which is preferable in terms of improving the performance of the zoom lens.

[0028] (c) Lens group having negative refractive power Moreover, it is preferable that the rear group includes a lens group having a negative refractive power. During magnification change, it is preferable to move the lens group having a negative refractive power arranged in the rear group toward the image side, since this can increase the focal length of the zoom lens at the telephoto end. However, when there are a plurality of lens groups having a negative refractive power arranged in the rear group, it is sufficient to move at least one of the lens groups toward the image side. Moreover, it is preferable that the lens group having a negative refractive power that is moved toward the image side is the object side group Rfn. By moving the lens group having a negative refractive power arranged in the rear group toward the image side, it is possible to increase the lateral magnification of the lens group having a negative refractive power at the telephoto end. Therefore, it is possible to increase the focal length of the zoom lens at the telephoto end while maintaining the zoom lens small.

[0029] In order to improve the image surface quality at intermediate focal lengths, it is preferable to move the lens group having negative refractive power arranged in the rear group along a locus convex toward the image side. If there are multiple lens groups having negative refractive power arranged in the rear group, it is sufficient to move at least one of the lens groups toward the image side.

[0030] Furthermore, among the lens groups having negative refractive power included in the rear group, the lens group having negative refractive power and arranged closest to the image side is designated as negative lens group n. It is preferable that negative lens group n is a lens group different from lens group R, which will be described next, and therefore, it is preferable that negative lens group n is arranged closer to the object side than lens group R.

[0031] (d) Lens group R Here, the lens group arranged closest to the image side in the rear group is referred to as lens group R. Lens group R may be the lens group Gp having the above-mentioned positive refractive power, or may be a lens group having a positive refractive power other than lens group Gp. Lens group R may also be a lens group having a negative refractive power.

[0032] In order to reduce the size of the zoom lens in the overall optical length direction at the telephoto end, it is preferable that the lens group R has a negative refractive power. By adopting a telephoto type refractive power arrangement in which a positive refractive power is arranged on the object side and a negative refractive power is arranged on the image side, the overall optical length of the zoom lens at the telephoto end can be made shorter compared to the focal length. If the lens group R has a negative refractive power, a refractive power arrangement that has a strong tendency toward the telephoto type can be adopted, which is preferable in terms of reducing the size of the zoom lens at the telephoto end.

[0033] (e) Other The zoom lens preferably has a lens group having negative refractive power on the object side of the lens group R. When the lens group R has negative refractive power, by disposing a lens group having negative refractive power on the object side of the lens group R, it is possible to achieve a refractive power arrangement that has a stronger tendency toward a telephoto type, which is preferable in terms of making the zoom lens more compact at the telephoto end.

[0034] In order to further improve the performance of the zoom lens, it is preferable that the rear group has at least one lens Lnr having negative refractive power. By disposing the lens Lnr having negative refractive power in the rear group, it is possible to improve the image surface characteristics and reduce chromatic aberration.

[0035] Furthermore, it is preferable that the rear group has at least one lens Lrp having a positive refractive power. As will be described later, it is more preferable that the lens Lrp is made of a glass material having high anomalous dispersion.

[0036] Here, in a telephoto zoom lens with a long focal length, the pupil diameter becomes large. Usually, an ND filter, a PL filter, etc. are arranged closest to the object side of the optical system. However, in a telephoto zoom lens with a focal length of more than 500 mm at the telephoto end in 35 mm format, for example, the diameter of the first lens group becomes large, and there are cases where a commercially available filter corresponding to such a diameter does not exist. It is preferable that the zoom lens unit is configured so that such a filter can be inserted into the rear group. In this case, it is preferable that the filter is fixed with respect to the image plane during zooming.

[0037] (3) Focus groups In the zoom lens, the presence or absence of a focus group is not particularly limited. When focusing, at least one lens in the zoom lens is moved in the optical axis direction, and the position and refractive power of the lens are not particularly limited.

[0038] Although the first lens group or a part thereof may be the focus group, it is more preferable to use one of the lens groups constituting the rear group or a part thereof as the focus group. The lens groups constituting the rear group have a smaller diameter than the first lens group, which is preferable in terms of making the focus group smaller and lighter. Furthermore, by making the focus group smaller and lighter, it is possible to make the drive mechanism for moving the focus group in the optical axis direction when focusing (hereinafter referred to as the focus drive mechanism) smaller and lighter. Therefore, it is preferable to make the entire zoom lens unit smaller, including the lens barrel portion of the zoom lens. Note that the zoom lens unit includes, in addition to the focus drive mechanism, a zoom drive mechanism for relatively moving each lens group when changing magnification, and a lens barrel that houses these.

[0039] Moreover, in order to suppress aberration fluctuations that occur when focusing on a close subject, it is preferable that the focus group be made up of a plurality of lenses.

[0040] Furthermore, it is preferable that the focus group is composed of one single lens unit. Here, the single lens unit refers to a lens unit such as one single lens or a cemented lens in which multiple single lenses are integrated without any air gap. In other words, even if the single lens unit has multiple optical surfaces, only the most object-side surface and the most image-side surface are in contact with air, and the other surfaces are not in contact with air. In addition, in this specification, the single lens may be either a spherical lens or an aspherical lens. In addition, the aspherical lens also includes a so-called composite aspherical lens having an aspherical film attached to its surface.

[0041] When the focus group is configured from the single lens unit, the focus group does not include an air gap. Therefore, compared to a configuration in which a plurality of single lenses are arranged with an air gap therebetween, the focus group can be made smaller and lighter by configuring the focus group from a single lens unit. As a result, the focus drive mechanism can be made even smaller and lighter, and the entire zoom lens unit can be made smaller and lighter.

[0042] Furthermore, by configuring the focus group from the single lens unit, various manufacturing errors such as decentering errors and errors in the air gap between the single lenses can be reduced compared to a configuration in which the focus group is configured with multiple single lenses with air gaps between them. This makes it possible to reduce the degradation of optical performance caused by manufacturing errors, and to reduce the variation in performance between products. This makes it possible to manufacture zoom lenses with high optical performance with a good yield.

[0043] The focus group may have a positive refractive power or a negative refractive power. When the focus group has a negative refractive power, the lateral magnification of the focus group can be increased compared to when the focus group has a positive refractive power, so that the focus sensitivity is increased and the focus movement amount can be reduced, which is preferable in terms of miniaturizing the zoom lens. The direction of movement of the focus group during focusing is not particularly limited, but when the focus group has a negative refractive power, it is preferable to move the focus group toward the image side when focusing from infinity to a close subject. In particular, it is more preferable that the focus group is the negative lens group n described above.

[0044] The lens surfaces included in the focus group may be spherical or may include aspheric surfaces. If the lens surfaces included in the focus group are spherical, it is preferable because it is possible to reduce costs. On the other hand, if at least one of the lens surfaces included in the focus group is aspheric, it is possible to configure a focus group with less aberration fluctuation during focusing with a small number of lenses, and the entire zoom lens unit including the focus drive mechanism can be made smaller. In this case, it is preferable that the aspheric surface has a shape that weakens the refractive power required from a paraxial spherical surface defined by the paraxial radius of curvature. By arranging an aspheric surface with such a shape in the focus group, it is possible to correct spherical aberration, coma aberration, and field curvature during focusing, and therefore it is possible to realize a zoom lens with higher optical performance over the entire focusing range.

[0045] Furthermore, when a focus group is provided in the rear group, it is preferable that the focus group is disposed closer to the object side than the lens group R, which is disposed closest to the image side. A flexible board or the like on which a control circuit or the like for electrically connecting the zoom lens to the imaging device body is mounted is disposed closest to the image side of the zoom lens. Therefore, when the lens group R or a part of it is used as the focus group, it is difficult to secure a space in the lens barrel for arranging various mechanical members constituting the focus drive mechanism, and it becomes necessary to increase the diameter of the lens barrel, making it difficult to configure the zoom lens compact. By arranging the focus group closer to the object side than the lens group R, it becomes easier to secure a space for arranging various mechanical members constituting the focus drive mechanism, and it is possible to reduce the diameter of the lens barrel of the zoom lens, thereby enabling the entire zoom lens unit to be compact.

[0046] When a focus group is provided in the rear group, it is preferable that the focus group is disposed on the image side of the lens group having positive refractive power. By disposing the focus group on the image side of the lens group having positive refractive power, the light beam converged by the lens group having positive refractive power can be made incident on the focus group, so that the diameter of the focus group can be made small. In addition, by making the diameter of the focus group small, the focus can be made lighter, which is preferable because it allows the entire zoom lens unit to be made smaller.

[0047] In the zoom lens, the lens groups or a part of the lens groups may be used as the focus group. That is, focusing may be performed by a floating method. By adopting the floating method, spherical aberration and image surface characteristics at close focusing can be improved, which is preferable in terms of high performance.

[0048] (4) Aperture diaphragm In the zoom lens, the location of the aperture diaphragm is not particularly limited, but it is preferable to place the aperture diaphragm in the rear group in order to reduce the size of the diaphragm unit. However, the aperture diaphragm referred to here is the diaphragm that determines the axial light beam diameter of the zoom lens, i.e., the F-number of the zoom lens.

[0049] The aperture unit refers to an aperture diaphragm, and mechanical members and a control board for controlling the operation of the aperture diaphragm. In this zoom lens, a light beam converged by the first lens group having a positive refractive power enters the rear group. Therefore, the diameter of the light beam incident on the rear group is smaller than that of the first lens group. Therefore, by arranging the aperture diaphragm in the rear group, the aperture diameter can be reduced. Furthermore, if the aperture diaphragm is arranged on the image side of the lens group Gp having a positive refractive power in the rear group, the lens group Gp can further converge the incident light beam, which is preferable in terms of reducing the diameter of the aperture diaphragm and reducing the size of the aperture unit.

[0050] Furthermore, when the lens group R, which is located closest to the image side in the rear group, is fixed relative to the image plane during zooming, it is preferable to provide an aperture diaphragm on the object side of the lens group R or within the lens group R. When the lens group R is fixed relative to the image plane during zooming, there is no change in the magnification of the lens group R, so there is no need to change the aperture diameter of the aperture diaphragm during zooming. This allows the F-number of the zoom lens to be constant during zooming.

[0051] (5) Anti-vibration group In the zoom lens, the presence or absence of an anti-vibration group is not particularly limited. For example, at least one of the lenses constituting the zoom lens may be decentered by moving it in a direction substantially perpendicular to the optical axis to correct image blur caused by camera shake or the like.

[0052] When providing such an anti-vibration group in the zoom lens, the location of the anti-vibration group is not particularly limited, but providing the anti-vibration group in the rear group is preferable in order to reduce the diameter of the anti-vibration group. The diameter of the light beam incident on the rear group is smaller than the diameter of the light beam incident on the front group. Therefore, by providing the anti-vibration group in the rear group, it is possible to reduce the size and weight of the anti-vibration group compared to when the anti-vibration group is provided in the front group.

[0053] It is also preferable that the vibration-reduction group is disposed closer to the image side than the aperture stop. Since the fluctuation in the height of the light ray during magnification is small on the image side of the aperture stop, the fluctuation in aberration during magnification is also small. Therefore, the fluctuation in aberration during vibration reduction can be reduced, and high optical performance can be maintained even during vibration reduction. Furthermore, by disposing the vibration-reduction group closer to the image side than the aperture stop, the amount of movement of the vibration-reduction group when correcting image blur by the vibration-reduction group can be reduced. Therefore, the vibration-reduction unit can be made more compact, and the entire zoom lens unit can be made more compact.

[0054] The vibration isolation group may have a positive refractive power or a negative refractive power, and the sign of the refractive power arranged in the vibration isolation group is not particularly limited. When the vibration isolation group has a negative refractive power, the amount of movement of the vibration isolation group during image blur correction can be reduced, which is preferable in terms of miniaturizing the entire zoom lens unit.

[0055] The number of lenses constituting the vibration-reduction group is not particularly limited. If the vibration-reduction group is composed of a plurality of lenses, it is preferable in terms of suppressing aberration fluctuations during vibration reduction. In this case, it is preferable that the vibration-reduction group has at least one lens having negative refractive power and at least one lens having positive refractive power. By having the vibration-reduction group have at least one lens having negative refractive power and at least one lens having positive refractive power, it is possible to suppress the occurrence of chromatic aberration during vibration reduction, and a zoom lens with higher optical performance can be realized.

[0056] It is more preferable that the vibration isolation group is composed of one lens having a negative refractive power and one lens having a positive refractive power. By constructing the vibration isolation group from only two lenses, it is possible to reduce the size and weight of the vibration isolation group, the size of the vibration isolation unit, and the size of the entire zoom lens unit.

[0057] When the vibration-proof group is composed of one lens having a negative refractive power and one lens having a positive refractive power, it is preferable that these two lenses are cemented together. That is, it is preferable that the vibration-proof group is composed of a single lens unit in which a lens having a negative refractive power and a lens having a positive refractive power are cemented together. By constructing the vibration-proof group from one single lens unit, it is possible to achieve a smaller size than a configuration in which a lens having a negative refractive power and a lens having a positive refractive power are arranged with an air gap between them, and it is also possible to reduce various manufacturing errors such as decentering errors and air gap errors between single lenses. Therefore, it is possible to reduce the deterioration of optical performance caused by manufacturing errors, and it is possible to reduce the variation in performance between products. Therefore, it is possible to manufacture zoom lenses with high optical performance with a high yield.

[0058] In addition, when the zoom lens is provided with an anti-vibration group, the lens surfaces included in the anti-vibration group may be spherical or may include aspheric surfaces. It is preferable in terms of reducing costs if all the lens surfaces included in the anti-vibration group are spherical.

[0059] On the other hand, if at least one of the lens surfaces included in the vibration-proof group is aspheric, it becomes easy to satisfy the optical performance required for the zoom lens even when the vibration-proof group is configured with a small number of lenses. Therefore, it is possible to configure the vibration-proof group with a small number of lenses, so that the vibration-proof group can be made smaller and lighter. In this case, it is preferable that the aspheric surface has a shape that weakens the refractive power required from the paraxial sphere defined by the paraxial curvature radius. By disposing an aspheric surface of such a shape in the vibration-proof group, coma aberration and one-sided blur during decentering can be corrected, so that a zoom lens with higher optical performance can be realized.

[0060] The vibration-proof group is preferably a lens group or a part thereof that is fixed in the optical axis direction relative to the image plane during zooming. In order to move the vibration-proof group in a direction perpendicular to the optical axis during vibration-proofing, a flexible board on which mechanical members for driving the vibration-proof group and electronic circuits for controlling the same are mounted is provided. If the vibration-proof group moves in the optical axis direction during zooming, it is difficult to secure space for accommodating the flexible board, etc., and it becomes difficult to achieve a compact size of the entire zoom lens unit. In addition, if the flexible board is bent and arranged inside the lens barrel, the vibration-proof group may become decentered due to a reaction force from the flexible board, which is undesirable because it may deteriorate the optical performance of the zoom lens.

[0061] In the rear group, when the lens group R arranged closest to the image has negative refractive power, it is preferable that the lens group R or a part of it is used as an image stabilization group. As described above, when the lens group R has negative refractive power, the zoom lens has a refractive power arrangement that tends to be a telephoto type, and the diameter of the lens group R can be reduced. Therefore, if the image stabilization group is arranged in the lens group R, the image stabilization group can be made smaller and lighter, making it easier to reduce the size of the image stabilization unit.

[0062] When a part of the lens group R is used as the vibration reduction group, it is preferable that at least one lens is arranged on the image side of the vibration reduction lens group. Furthermore, it is preferable that the composite focal length of all the lenses arranged on the image side of the vibration reduction group is negative. By arranging a lens with a negative refractive power on the image side of the vibration reduction group, it is possible to increase the blur correction coefficient of the vibration reduction group, i.e., the amount of image plane movement per unit movement of the vibration reduction group, so that the amount of movement of the vibration reduction group during vibration reduction can be reduced, making it easier to miniaturize the vibration reduction unit.

[0063] (7) Lens group configuration The number of lens groups constituting the zoom lens is not particularly limited, but various lens group configurations can be adopted, such as a seven-group zoom lens consisting of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, and a seventh lens group having negative refractive power, with the second lens group and subsequent groups being the rear group, and a six-group zoom lens consisting of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having negative refractive power, with the second lens group and subsequent groups being the rear group. The specific lens group configuration of the zoom lens is not particularly limited as long as it is configured to include a first lens group having positive refractive power and a rear group in order from the object side.

[0064] 1-2. Operation when changing magnification In the zoom lens, the air space between adjacent lens groups is changed when changing magnification from the wide-angle end to the telephoto end. Also, it is preferable that the air space between the lens groups is changed so that the space between the first lens group and the rear group increases when changing magnification from the wide-angle end to the telephoto end.

[0065] The rear group has at least one lens group Gp having a positive refractive power, and may have other lens groups. When the rear group includes a plurality of lens groups, the air gap between adjacent lens groups in the rear group also changes. When the magnification is changed from the wide-angle end to the telephoto end, it is sufficient that the air gap between adjacent lens groups changes, and the increase or decrease in the air gap between each lens group is not particularly limited. In order to obtain a high magnification ratio, it is preferable that the air gap between the first lens group and the lens group arranged closest to the object in the rear group increases, but the increase or decrease in the air gap between the other lens groups is not particularly limited. In addition, when the magnification is changed, all of 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, and the presence or absence of movement of each lens group and the direction of movement are not particularly limited.

[0066] In the case of a large zoom lens with a long focal length, such as an entrance pupil diameter exceeding 80 mm, the weight of the first lens group exceeds several hundred grams. In order to move such a heavy lens group to a predetermined position with high precision during magnification change, the load applied to the mechanical members for driving the first lens group is large, and the mechanical structure for controlling the operation of the zoom lens during magnification change is also large. Therefore, in order to reduce the size and weight of the entire zoom lens unit, it is preferable to fix the first lens group, which is disposed closest to the object side in the zoom lens, in the optical axis direction relative to the image plane during magnification change. Furthermore, if the first lens group is fixed relative to the image plane, the movement of the center of gravity is also reduced, making it easier to suppress image blur during image capture.

[0067] Furthermore, by fixing the first lens group in the optical axis direction relative to the image plane during zooming, there is no change in the length of the lens barrel, which makes it easier to make at least the object side of the lens barrel watertight, and this is preferable because it makes it easier to prevent dust and moisture from entering the lens barrel from the object side.

[0068] Furthermore, by fixing the lens group R, which is located closest to the image side in the rear group, in the optical axis direction relative to the image plane during magnification change, it becomes easy to make the image side of the lens barrel watertight, which is preferable because it makes it easier to prevent dust and moisture from entering the lens barrel from the image side. In addition, by making the lens group R a fixed group, the diameter of the lens barrel can be made smaller, as described above.

[0069] 1-3.Conditional Expressions In the zoom lens, it is preferable that the above-mentioned configuration is adopted and that one or more of the following conditional expressions are satisfied.

[0070] 1-3-1.Conditional expression (1) 3.50 < ft / fnot / Y < 9.00 (1) however, ft: focal length of the zoom lens at the telephoto end fnot: F-number of the zoom lens at the telephoto end Y: Maximum image height of the zoom lens

[0071] The above conditional formula (1) defines the size of the entrance pupil diameter. By satisfying conditional formula (1), the entrance pupil diameter becomes appropriate. Therefore, while achieving a telephoto zoom of the zoom lens, it is possible to prevent the diameter of the first lens group from becoming large, and to reduce the weight of the zoom lens.

[0072] On the other hand, if the numerical value of conditional formula (1) is equal to or greater than the upper limit, the entrance pupil diameter becomes too large. The diameter of the lenses constituting the first lens group is larger than the entrance pupil diameter. This makes it difficult to reduce the weight of the first lens group, which is undesirable. On the other hand, if the numerical value of conditional formula (1) is equal to or less than the lower limit, it makes it difficult to achieve a telephoto zoom lens, which is undesirable.

[0073] In order to obtain the above effects, the lower limit of conditional formula (1) is more preferably 3.90, even more preferably 4.20, even more preferably 4.50, and even more preferably 4.70, while the upper limit of conditional formula (1) is more preferably 8.00, even more preferably 7.50, even more preferably 7.00, and even more preferably 6.50.

[0074] 1-3-2.Conditional expression (2) 63.0 < νdL1p1 < 76.0 (2) however, νdL1p1: Abbe number at the d line of lens L1p1

[0075] The above conditional expression (2) defines the Abbe number at the d-line of the lens L1p1 having positive refractive power included in the first lens group. By satisfying conditional expression (2), chromatic aberration can be corrected well, and a zoom lens with high optical performance can be realized while reducing the weight of the zoom lens.

[0076] On the other hand, when the value of conditional formula (2) is equal to or greater than the upper limit, the Abbe number at the d-line of lens L1p1 becomes large. Glass materials with large Abbe numbers tend to have large specific gravity. In addition, the first lens group is composed of lenses with a larger diameter than the other lens groups. For the same diameter, a lens with positive refractive power is heavier than a lens with negative refractive power by the amount of its thickness. Therefore, when the value of conditional formula (2) is equal to or greater than the upper limit, it becomes difficult to reduce the weight of the first lens group, which is undesirable. On the other hand, when the value of conditional formula (2) is equal to or less than the lower limit, it becomes difficult to correct chromatic aberration at the telephoto end, which is undesirable in that it becomes difficult to realize a zoom lens with high optical performance.

[0077] In order to obtain the above-mentioned effects, the lower limit of conditional formula (2) is more preferably 64.0, even more preferably 66.0, and even more preferably 68.0.The upper limit of conditional formula (2) is more preferably 74.0, even more preferably 72.0, and even more preferably 71.0.

[0078] 1-3-3.Conditional expression (3) 32.0 < νdLpn < 65.0 (3) however, νdLpn: Abbe number at the d line of lens Lpn

[0079] The above conditional formula (3) is a formula that defines the Abbe number at the d-line of the lens Lpn having negative refractive power included in the lens group Gp. If the lenses constituting the first lens group are made of a glass material with a low specific gravity in order to reduce the weight of the first lens group, the chromatic aberration occurring in the first lens group will be undercorrected. Therefore, it is necessary to correct the chromatic aberration that cannot be sufficiently corrected in the first lens group in the rear group. In order to reduce the weight of the first lens group, it is effective to make the lens having positive refractive power included in the first lens group from a glass material with a low specific gravity. In this case, by making the lens Lpn having negative refractive power arranged in the lens group Gp having positive refractive power in the rear group from a glass material that satisfies the above conditional formula (3), it is possible to satisfactorily correct the longitudinal chromatic aberration, and to realize a zoom lens with high optical performance and reduced weight.

[0080] In contrast, when the numerical value of conditional formula (3) is equal to or greater than the upper limit, the Abbe number of the lens Lpn at the d-line becomes large. In that case, the correction of axial chromatic aberration becomes insufficient. On the other hand, when the numerical value of conditional formula (3) is equal to or less than the lower limit, the Abbe number of the lens Lpn at the d-line becomes small. In that case, the correction of chromatic aberration at the telephoto end becomes excessive. Therefore, in either case, it becomes difficult to realize a zoom lens with high optical performance, which is undesirable.

[0081] In order to obtain the above effects, the lower limit of conditional formula (3) is more preferably 33.0, even more preferably 35.0, even more preferably 37.0, and even more preferably 38.0, while the upper limit of conditional formula (3) is more preferably 62.0, even more preferably 59.0, even more preferably 56.0, even more preferably 55.0, and even more preferably 54.0.

[0082] 1-3-4.Conditional expression (4) 0.25 < f1 / ft < 0.65 (4) however, f1: focal length of the first lens group

[0083] Conditional expression (4) is an expression for defining the ratio between the focal length of the first lens group and the focal length of the zoom lens at the telephoto end. By satisfying conditional expression (4), the refractive power of the first lens group falls within an appropriate range, making it easier to realize a zoom lens that has high optical performance and is compact.

[0084] On the other hand, if the value of conditional formula (4) is below the lower limit, the refractive power of the first lens group becomes too large, resulting in large spherical aberration and curvature of field at the telephoto end, and in order to correct this, it is necessary to increase the number of lenses for aberration correction, which is undesirable because it becomes difficult to realize a zoom lens that has high optical performance and is small and lightweight. Also, if the value of conditional formula (4) is above the upper limit, the refractive power of the first lens group becomes too small. Therefore, it becomes difficult to shorten the overall optical length of the zoom lens at the telephoto end, which is undesirable because it becomes difficult to miniaturize the zoom lens.

[0085] In order to obtain the above effects, the lower limit of conditional formula (4) is more preferably 0.26, even more preferably 0.27, even more preferably 0.28, even more preferably 0.29, and even more preferably 0.30. The upper limit of conditional formula (4) is more preferably 0.60, even more preferably 0.56, even more preferably 0.52, even more preferably 0.48, and even more preferably 0.45.

[0086] 1-3-5.Conditional expression (5) 1.20 < βRT < 2.50 (5) however, βRT: Lateral magnification of lens group R at the telephoto end

[0087] Conditional formula (5) is a formula for defining the lateral magnification of the lens unit R located closest to the image side in the rear group. By satisfying conditional formula (5), a refractive power arrangement with a strong telephoto tendency can be achieved, and the overall optical length of the zoom lens at the telephoto end can be made shorter than the focal length, making it easier to reduce the size of the zoom lens.

[0088] On the other hand, when the value of conditional formula (5) is equal to or less than the lower limit, the lateral magnification of the lens group R becomes small and the tendency to telephoto becomes weak, making it difficult to shorten the total optical length at the telephoto end compared to the focal length, and making it difficult to miniaturize the zoom lens, which is undesirable. On the other hand, when the value of conditional formula (5) is equal to or greater than the upper limit, the lateral magnification of the lens group R becomes large and the effect of magnifying various aberrations also becomes large. As a result, it becomes difficult to correct aberrations at the telephoto end, and in order to realize a zoom lens with high optical performance, it is necessary to increase the number of lenses for aberration correction. As a result, it becomes difficult to realize a zoom lens with high optical performance that is small and lightweight, which is undesirable.

[0089] In order to obtain the above-mentioned effects, the lower limit of conditional formula (5) is more preferably 1.25, even more preferably 1.30, even more preferably 1.35, even more preferably 1.40, and even more preferably 1.45. The upper limit of conditional formula (5) is more preferably 2.45, even more preferably 2.40, even more preferably 2.35, even more preferably 2.30, and even more preferably 2.20.

[0090] 1-3-6.Conditional expression (6) 2.50 < βnRT < 6.00 (6) however, βnRT: The composite lateral magnification at the telephoto end from the negative lens unit n to the lens unit R

[0091] Conditional formula (6) is a formula for defining the composite lateral magnification at the telephoto end of the lens located on the image side from the negative lens group n. As described above, the negative lens group n refers to the lens group having negative refractive power that is located closest to the image side among the lens groups having negative refractive power included in the rear group. By satisfying conditional formula (6), a refractive power arrangement with a stronger telephoto tendency is obtained, and the total optical length at the telephoto end can be made shorter compared to the focal length, making it easier to miniaturize the zoom lens.

[0092] On the other hand, if the value of conditional formula (6) is equal to or less than the lower limit, the composite lateral magnification at the telephoto end by the lens groups arranged after the negative lens group n becomes small, and the telephoto tendency weakens, making it difficult to shorten the total optical length at the telephoto end compared to the focal length, and making it difficult to miniaturize the zoom lens, which is undesirable. Also, if the value of conditional formula (6) is equal to or greater than the upper limit, the composite lateral magnification at the telephoto end by the lens groups arranged after the negative lens group n becomes large, and the magnification effect of various aberrations also becomes large. Therefore, it becomes difficult to correct aberrations at the telephoto end, and in order to realize a zoom lens with high optical performance, it is necessary to increase the number of lenses for aberration correction. Therefore, it becomes difficult to realize a zoom lens with high optical performance and a small and lightweight design, which is undesirable.

[0093] In order to obtain the above effects, the lower limit of conditional formula (6) is more preferably 2.55, even more preferably 2.60, even more preferably 2.65, even more preferably 2.70, and even more preferably 2.75. The upper limit of conditional formula (5) is more preferably 5.80, even more preferably 5.50, even more preferably 5.20, even more preferably 5.00, and even more preferably 4.70.

[0094] 1-3-7.Conditional Expression (7) 1.79 < NdL1n < 1.92 (7) however, NdL1n: Refractive index at the d line of lens L1n

[0095] Conditional formula (7) is a formula for defining the refractive index at the d-line of the lens L1n having negative refractive power included in the first lens group. In the lens group having positive refractive power, it is common to correct the Petzval sum by making the lens having negative refractive power made of a high refractive index glass material and the lens having positive refractive power made of a low refractive index glass material. However, since high refractive index glass material is expensive, if the refractive index of the lens L1n is too high, it becomes difficult to configure the zoom lens at low cost. In addition, since high refractive index glass material has a large specific gravity, it is not preferable in terms of reducing the weight of the zoom lens. By satisfying conditional formula (7), it is possible to reduce the cost and weight of the zoom lens while ensuring good image surface quality.

[0096] On the other hand, if the value of conditional expression (7) is equal to or less than the lower limit, the refractive index of lens L1n becomes small, which is undesirable as it makes it difficult to correct the image plane. Also, if the value of conditional expression (7) is equal to or greater than the upper limit, the refractive index of lens L1n becomes large. Glass materials with high refractive indices tend to be expensive and have a high specific gravity. Therefore, if the value of conditional expression (7) is equal to or greater than the upper limit, it is undesirable in terms of reducing the cost and weight of the zoom lens.

[0097] When the first lens group includes a plurality of lenses L1n having negative refractive power, it is sufficient that one of them satisfies conditional expression (7). Any of the lenses L1n having negative refractive power included in the first lens group may satisfy conditional expression (7), but in order to better correct lateral chromatic aberration, it is preferable that the lens L1n arranged closest to the object in the first lens group satisfies conditional expression (7).

[0098] In order to obtain the above-mentioned effect, it is more preferable that the lower limit value of conditional expression (7) be 1.80, and the upper limit value of conditional expression (7) be 1.91.

[0099] 1-3-8.Conditional expression (8) 0.010 < ΔPgFLrp < 0.070 (8) however, ΔPgFLrp: Anomalous dispersion of the lens with the largest anomalous dispersion among the lenses Lrp with positive refractive power included in the rear group. Here, anomalous dispersion refers to the deviation of the partial dispersion ratio from the reference line when the line passing through the partial dispersion ratios and the coordinates of νd of C7 (partial dispersion ratio: 0.5393, νd: 60.49) and F2 (partial dispersion ratio: 0.5829, νd: 36.30) is used as the reference line.

[0100] Conditional formula (8) is a formula for defining the anomalous dispersion of the lens Lrp when the rear group includes at least one lens Lrp having a positive refractive power. In general, chromatic aberration is corrected by making the lens having a negative refractive power made of a high-dispersion glass material and the lens having a positive refractive power made of a low-dispersion glass material. However, in the case of high-dispersion glass material, the refractive index changes in a positive quadratic curve from short wavelengths to long wavelengths in the wide visible range, whereas in the case of low-dispersion glass material, the refractive index changes linearly, so that it is difficult to correct chromatic aberration adequately in all wavelength ranges even if these two lenses are combined. On the other hand, in the case of a lens made of a glass material having positive anomalous dispersion, the refractive index changes in a positive quadratic curve from short wavelengths to long wavelengths, similar to that of a high-dispersion glass material. Therefore, if the lens having a positive refractive power is made of a glass material having positive anomalous dispersion, it becomes easy to correct chromatic aberration adequately even in the long wavelength range. Therefore, by satisfying conditional expression (8), chromatic aberration of the zoom lens from the wide-angle end to the telephoto end can be corrected more satisfactorily, making it easier to realize a zoom lens having high optical performance over the entire magnification range.

[0101] On the other hand, if the value of conditional formula (8) is equal to or less than the lower limit, the anomalous dispersion of the lens Lrp becomes small, which makes it difficult to properly correct chromatic aberration over the entire wide visible range, which is not preferable. Also, if the value of conditional formula (8) is equal to or greater than the upper limit, the anomalous dispersion of the lens Lrp becomes large, which is preferable in terms of correcting chromatic aberration, but is not preferable in terms of reducing the cost of the zoom lens, since glass materials with high anomalous dispersion are generally expensive.

[0102] In order to obtain the above-mentioned effects, the lower limit of conditional formula (8) is preferably 0.015, more preferably 0.019, even more preferably 0.022, even more preferably 0.025, and even more preferably 0.027. The upper limit of conditional formula (8) is preferably 0.065, and even more preferably 0.060.

[0103] The rear group may have at least one lens Lrp having positive refractive power. When the rear group includes one lens Lrp, it is preferable that the lens Lrp satisfies conditional expression (8). When the rear group includes multiple lenses Lrp, it is only necessary that the lens having the greatest anomalous dispersion satisfies conditional expression (8). The rear group may also include multiple lenses that satisfy conditional expression (8). If the rear group includes multiple lenses having positive refractive power and that satisfy conditional expression (8), chromatic aberration can be corrected more effectively, and a zoom lens with high optical performance can be more easily realized. In addition, when the anomalous dispersion of the lens having the largest anomalous dispersion among the lenses having negative refractive power included in the rear group is defined in the same manner as above, it is also preferable to satisfy a condition similar to the above conditional expression (8).

[0104] 1-3-9.Conditional Expression (9) 0.80 < f1 / fw < 3.00 (9) however, f1: focal length of the first lens group fw: focal length at the wide-angle end of the zoom lens

[0105] Conditional expression (9) is an expression for defining the ratio between the focal length of the first lens group and the focal length of the zoom lens at the wide-angle end. By satisfying conditional expression (9), the refractive power of the first lens group can be set within an appropriate range, making it easy to achieve a compact zoom lens at the wide-angle end and realizing a zoom lens with high optical performance.

[0106] On the other hand, when the value of conditional expression (9) is below the lower limit, the refractive power of the first lens group becomes too large, so that the amount of curvature of field at the wide-angle end increases. This leads to a decrease in optical performance at the wide-angle end, which is not preferable. On the other hand, when the value of conditional expression (9) is above the upper limit, the refractive power of the first lens group becomes too small. This leads to a long optical total length at the wide-angle end, which is not preferable in terms of size reduction.

[0107] In order to obtain the above effects, the lower limit of conditional formula (9) is more preferably 0.84, even more preferably 0.88, even more preferably 0.92, even more preferably 0.96, and even more preferably 1.00. The upper limit of conditional formula (9) is more preferably 2.80, even more preferably 2.60, even more preferably 2.40, even more preferably 2.10, and even more preferably 1.80.

[0108] 1-3-10.Conditional expression (10) 1.83 < NdLnr < 2.20 (10) however, NdLnr: Refractive index of lens Lnr at the d line

[0109] Conditional formula (10) is a formula for prescribing the refractive index at the d-line of the lens Lnr having negative refractive power included in the rear group. As described above, it is common to correct the Petzval sum by making the lens having negative refractive power from a high refractive index glass material and the lens having positive refractive power from a low refractive index glass material. However, since high refractive index glass materials are expensive, if the refractive index of the lens Lnr is too high, it becomes difficult to configure the zoom lens at low cost. In addition, since high refractive index glass materials have a large specific gravity, they are not preferable in terms of reducing the weight of the zoom lens. By satisfying conditional formula (10), it is possible to ensure good image surface characteristics and to reduce the cost and weight of the zoom lens.

[0110] On the other hand, if the value of conditional expression (10) is equal to or less than the lower limit, the refractive index of the lens Lnr becomes small, which is undesirable as it makes it difficult to correct the image plane. Also, if the value of conditional expression (10) is equal to or greater than the upper limit, the refractive index of the lens Lnr becomes large. Glass materials with high refractive indices are expensive and tend to have high specific gravity. Therefore, if the value of conditional expression (10) is equal to or greater than the upper limit, it is undesirable in terms of reducing the cost and weight of the zoom lens.

[0111] When the rear group includes multiple lenses Lnr having negative refractive power, it is sufficient that one of them satisfies conditional formula (10). Any of the lenses Lnr having negative refractive power included in the rear group may satisfy conditional formula (10).

[0112] In order to obtain the above effects, the lower limit of condition (10) should preferably be 1.86, more preferably be 1.88, and even more preferably be 1.89.The upper limit of condition (10) should preferably be 2.10, more preferably be 2.06, even more preferably be 2.01, even more preferably be 1.96, and even more preferably be 1.92.

[0113] In order to reduce the Petzval sum in a lens group having positive refractive power, the negative lens included in the lens group is required to be made of a glass material with a high refractive index. Therefore, in order to improve the image surface quality of the zoom lens, it is more preferable that the lens Lnr satisfying conditional expression (10) is included in the lens group having positive refractive power in the rear group.

[0114] 1-3-11.Conditional formula (11) 0.80 < BFw / (fw×tanωw) < 4.50 ···(11) however, BFw: The air equivalent length of the zoom lens at the wide-angle end from the lens surface closest to the image plane to the image plane fw: focal length of the zoom lens at the wide-angle end ωw: Half angle of view of the most off-axis chief ray of the zoom lens when focused at infinity at the wide-angle end

[0115] Conditional expression (11) is an expression for defining the ratio between the back focus at the wide-angle end of the zoom lens and the maximum image height on the image plane. By satisfying conditional expression (11), it is possible to realize a compact zoom lens while ensuring a back focus suitable for an interchangeable lens at the wide-angle end.

[0116] On the other hand, if the numerical value of conditional expression (11) is equal to or less than the lower limit, i.e., if the back focus becomes too short for the maximum image height, it becomes difficult to ensure a back focus suitable for an interchangeable lens at the wide-angle end, which is not preferable.Also, if the numerical value of conditional expression (11) is equal to or more than the upper limit, i.e., if the back focus becomes long for the maximum image height, it becomes difficult to achieve a compact zoom lens at the wide-angle end, which is not preferable.

[0117] In order to obtain the above-mentioned effects, the lower limit of conditional formula (11) is more preferably 0.90, even more preferably 1.50, and even more preferably 1.80.The upper limit of conditional formula (11) is more preferably 4.00, even more preferably 3.50, even more preferably 3.20, even more preferably 2.90, and even more preferably 2.80.

[0118] 1-3-12.Conditional expression (12) 0.40 < Lt / ft < 0.75 (12) however, Lt: The distance from the lens surface closest to the object to the image plane at the telephoto end of the zoom lens ft: focal length of the zoom lens at the telephoto end

[0119] Conditional expression (12) is an expression for defining the ratio between the total optical length of the zoom lens at the telephoto end and the focal length of the zoom lens at the telephoto end. By satisfying conditional expression (12), the ratio between the total optical length of the zoom lens at the telephoto end and the focal length of the zoom lens at the telephoto end becomes favorable, and it is possible to realize a zoom lens that is short in total optical length compared to the focal length, is small and lightweight, and has high optical performance.

[0120] On the other hand, if the value of conditional expression (12) is equal to or less than the lower limit, i.e., if the total optical length at the telephoto end is too short compared to the focal length, it becomes difficult to satisfactorily correct various aberrations at the telephoto end, and the optical performance deteriorates. In addition, the error sensitivity increases, and the deterioration of the optical performance caused by manufacturing errors increases, resulting in a large variation in performance between products. On the other hand, if the value of conditional expression (12) is equal to or more than the upper limit, i.e., if the total optical length at the telephoto end is long compared to the focal length, the amount of movement of each lens group during zooming increases in order to obtain a predetermined zoom ratio, which leads to an increase in the size of a zoom drive mechanism for moving each lens group along the optical axis, making it difficult to reduce the weight of the zoom lens unit.

[0121] In order to obtain the above-mentioned effects, the lower limit of conditional formula (12) should preferably be 0.42, more preferably be 0.45, even more preferably be 0.48, and even more preferably be 0.51.The upper limit of conditional formula (12) should preferably be 0.72, even more preferably be 0.70, even more preferably be 0.68, even more preferably be 0.66, and even more preferably be 0.64.

[0122] 2. Imaging device Next, an image pickup device according to the present invention will be described, which is characterized by including the zoom lens according to the present invention and an image pickup element provided on the image plane side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

[0123] Here, the imaging element is not particularly limited, 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. The imaging device may be a fixed-lens imaging device in which a lens is fixed to a housing, or may be an interchangeable-lens imaging device, such as a single-lens reflex camera or a mirrorless single-lens camera. In particular, the zoom lens according to the present invention can ensure a back focus suitable for an interchangeable lens system. Therefore, it is suitable for imaging devices such as single-lens reflex cameras equipped with an optical finder, a phase difference sensor, and a reflex mirror for branching light to these sensors.

[0124] It is more preferable that the imaging device has an image processing section that electrically processes the captured image data acquired by the imaging element to change the shape of the captured image, and an image correction data storage section that stores image correction data, image correction programs, etc., used to process the captured image data in the image processing section. When the zoom lens is made compact, the captured image shape formed on the imaging surface is easily distorted. In this case, it is preferable that the image correction data storage section stores distortion correction data for correcting the distortion of the captured image shape in advance, and the image processing section corrects the distortion of the captured image shape using the distortion correction data stored in the image correction data storage section. With such an imaging device, the zoom lens can be made even more compact, and a beautiful captured image can be obtained while the entire imaging device can be made compact.

[0125] Furthermore, in the imaging device according to the present invention, it is preferable that the image correction data storage unit stores magnification chromatic aberration correction data in advance, and the image processing unit performs magnification chromatic aberration correction of the captured image using the magnification chromatic aberration correction data stored in the image correction data storage unit. By correcting the magnification chromatic aberration, i.e., chromatic distortion aberration, by the image processing unit, it is possible to reduce the number of lenses constituting the optical system. Therefore, with such an imaging device, it is possible to further reduce the size of the zoom lens, obtain a beautiful captured image, and reduce the size of the entire imaging device.

[0126] Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. EXAMPLES

[0127] (1) Optical configuration of zoom lens FIG. 1 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 1 according to the present invention at the wide-angle end when focusing on infinity. The zoom lens is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having negative refractive power. An aperture stop S is disposed on the object side of the seventh lens group G7. In this example, the rear group is composed of the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7. The lens group Gp having positive refractive power is the fourth lens group G4. The rear group is composed of an object side group Rfn and an image side group Rrp. In this embodiment, the object side group Rfn is composed of a second lens group G2 and a third lens group G3. The image side group Rrp is composed of a fourth lens group G4, a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7.

[0128] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2 are cemented together, and a positive meniscus lens L3 with a convex shape toward the object side. The biconvex lens L2 is the lens L1p1 referred to in the present invention, and the positive meniscus lens L3 with a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 with a convex shape toward the object side is the lens L1n referred to in the present invention. Among the lenses with positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is the lens L3. The ΔPgF of the lens L3 is 0.0375. The average linear expansion coefficient α1n of the lens L1 is 71×10 -7 / °C, and the average linear expansion coefficient α1p of the lens L2 is 93×10 -7 / ℃.

[0129] The second lens group G2 is composed of a cemented lens in which, in order from the object side, a biconvex lens L4 and a biconcave lens L5 are cemented together.

[0130] The third lens group G3 is composed of, in order from the object side, a cemented lens in which a biconcave lens L6 and a biconvex lens L7 are cemented together, and a biconcave lens L8.

[0131] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L9, a biconvex lens L10, and a cemented lens formed by cementing a biconvex lens L11 and a biconcave lens L12. The biconcave lens L12 is the lens Lpn and also the lens Lnr referred to in the present invention. The biconvex lens L9, the biconvex lens L10, and the biconvex lens L11 are the lens Lrp referred to in the present invention, and ΔPgFLrp is 0.0375.

[0132] The fifth lens group G5 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape facing the object side and a biconvex lens L14 are cemented together. The negative meniscus lens L13 having a convex shape facing the object side is the lens Lnr referred to in the present invention.

[0133] The sixth lens group G6 is composed of a cemented lens in which a convex lens L15 and a biconcave lens L16 are cemented together.

[0134] The seventh lens group G7 is composed of, in order from the object side, an aperture stop S, a cemented lens in which a negative meniscus lens L17 having a convex shape toward the object side and a biconvex lens L18 are cemented together, a cemented lens in which a convex lens L19 and a biconcave lens L20 are cemented together, a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented together, a lens L23 which is a parallel plate having no substantial refractive power, and a cemented lens in which a biconvex lens L24 and a biconcave lens L25 are cemented together. The lens L23 is a filter such as an ND filter or a PL filter. The filter is configured so that it can be freely inserted into the zoom lens unit, and the filter is inserted from the outside of the lens barrel. The filter is an optional configuration in the zoom lens according to the present invention. In the following, in other embodiments, a filter similar to the filter is called an insert filter.

[0135] In the zoom lens of Example 1, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction relative to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the image side, the fourth lens group G4 moves to draw a convex locus toward the image side, the fifth lens group G5 is fixed in the optical axis direction, the sixth lens group G6 moves to draw a convex locus toward the image side, and the seventh lens group G7 is fixed in the optical axis direction.

[0136] Here, among the lens groups included in the rear group, if the lens group having negative refractive power is moved relative to the lens group on the object side so as to draw a convex locus toward the image side when changing magnification from the wide-angle end to the telephoto end, the image surface quality at the intermediate focal length is improved. In this embodiment, the sixth lens group G6 is moved relative to the fifth lens group G5 so as to draw a convex locus toward the image side when changing magnification from the wide-angle end to the telephoto end, thereby ensuring good image surface quality at the intermediate focal length. In this embodiment, the sixth lens group is a focus group, and when focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the image side along the optical axis.

[0137] In addition, when camera shake or the like occurs, it is preferable to correct image blur by decentering at least one lens included in the zoom lens. In this embodiment, for example, a cemented lens in which a convex lens L19 and a biconcave lens L20 included in the seventh lens group G7 are cemented together is used as an anti-vibration group, and it is preferable to shift the image when camera shake or the like occurs by moving the anti-vibration group in a direction perpendicular to the optical axis, thereby correcting image blur.

[0138] 1 indicates an image plane, specifically an imaging surface of a solid-state imaging element such as a CCD sensor or a CMOS sensor, or a film surface of a silver halide film. A parallel plate having no substantial refractive power, such as a cover glass CG, is provided on the object side of the image plane IMG. These points are the same in the lens cross-sectional views shown in the other embodiments, and therefore will not be described below.

[0139] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. Table 1 shows the surface data of the zoom lens. In Table 1, the "surface number" is the order of the lens surface counted from the object side, "r" is the radius of curvature of the lens surface, "d" is the distance on the optical axis of the lens surface, "Nd" is the refractive index for the d-line (wavelength λ=587.6 nm), "vd" is the Abbe number for the d-line, and "H" is the effective radius. In addition, "S" displayed in the column next to the surface number represents the aperture stop. Furthermore, "D6", "D16", etc., shown in the column of the distance on the optical axis of the lens surface mean that the distance on the optical axis of the lens surface is a variable distance that changes when changing the magnification or focusing. In each table, the unit of length is all "mm", and the unit of the angle of view is all "°". In addition, "0.0000" in the radius of curvature means a flat surface. In addition, the 46th and 47th surfaces in Table 1 are surface data of the insert filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

[0140] Table 2 is a specification table of the zoom lens. The specification table shows the focal length "f", F-number "Fno.", half angle of view "ω", image height "Y", and total optical length "TL" of the zoom lens when focused at infinity. However, from the left, Table 2 shows the respective values ​​at the wide-angle end, the mid-focal length state, and the telephoto end.

[0141] Table 3 shows the variable distances on the optical axis of the zoom lens when changing magnification. From the left, Table 3 shows the values ​​at the wide-angle end, the intermediate focal length state, and when focusing on infinity at the telephoto end. In the table, "INF" stands for "∞ (infinity)."

[0142] Table 4 shows the variable distance on the optical axis of the zoom lens when in focus. Table 4 also shows the values ​​when the shooting distance (imaging distance) is 2900.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance for each focal length.

[0143] Table 5 shows the focal length of each lens group that constitutes the zoom lens.

[0144] Table 21 shows the values ​​of the conditions (1) to (12) and the values ​​used in the calculations of the conditions (1) to (12).

[0145] The matters relating to these tables are the same as those in the tables shown in the other embodiments, so the explanation will be omitted below.

[0146] [Table 1] Surface number rd Nd vd H 1 522.4744 3.600 1.80610 33.27 59.057 2 186.4038 0.020 1.56732 42.84 58.374 3 186.4038 13.850 1.48749 70.24 58.374 4 -566.6007 0.380 58.350 5 136.5404 13.294 1.49700 81.61 57.741 6 733.3234 D6 57.262 7 3020.7490 4.976 1.80518 25.46 26.400 8 -113.1128 0.010 1.56732 42.84 26.183 9 -113.1128 1.970 1.72916 54.67 26.181 10 100.1107 D10 25.045 11 -322.8543 2,000 1.61396 36.64 24.783 12 83.5699 0.010 1.56732 42.84 24.766 13 83.5699 5.300 1.84389 23.02 24.766 14 -694.2165 2.826 24.721 15 -118.7271 1.980 1.80162 31.00 24.649 16 260.1413 D16 24.860 17 186.8259 7.008 1.49700 81.61 25.312 18 -103.8300 0.400 25.280 19 125.3658 5.580 1.49700 81.61 25.204 20 -313.2811 0.300 25.050 21 69.9627 8.670 1.49700 81.61 24.175 22 -115.5431 0.010 1.56732 42.84 23.749 23 -115.5431 2.055 1.84701 40.81 23.747 24 173.7470 D24 22.920 25 75.7853 1.490 1.91082 35.25 20.412 26 42.2173 0.010 1.56732 42.84 19.601 27 42.2173 7.200 1.69680 55.46 19.599 28 -3787.7656 D28 19.157 29 -325.1337 3.200 1.85230 22.25 15.467 30 -103.4591 0.010 1.56732 42.84 15.054 31 -103.4591 1.000 1.72916 54.67 15.052 32 66.3660 D32 14.352 33 S 0.0000 2.000 10.000 34 354.2484 1.043 1.90366 31.31 9.735 35 42.9990 0.010 1.56732 42.84 9.580 36 42.9990 5.123 1.63177 43.20 9.580 37 -48.4994 5.795 9.500 38 -1493.8738 3.600 1.70341 29.67 10.071 39 -43.1806 0.010 1.56732 42.84 9.967 40 -43.1806 1.010 1.72916 54.67 9.967 41 38.5434 5.348 9.836 42 84.4813 5.000 1.60403 37.79 9.735 43 -26.6873 0.010 1.56732 42.84 9.820 44 -26.6873 1.000 1.83916 39.32 9.820 45 203.1004 13.814 10.065 46 0.0000 2.000 1.51680 64.20 12.635 47 0.0000 12.514 12.882 48 51.4153 6.760 1.55740 45.41 15.719 49 -57.7421 0.010 1.56732 42.84 15.721 50 -57.7421 1.200 1.74530 48.09 15.721 51 242.6126 53.863 15.843 52 0.0000 2.000 1.51680 64.20 21.423 53 0.0000 1.000 21.563

[0147] [Table 2] f 205.426 447.698 774.302 Fno. 6.583 6.586 6.583 ω 6.008 2.752 1.586 Y 21.633 21.633 21.633 TL 415.348 415.348 415.348

[0148] [Table 3] f 205.426 447.698 774.302 Shooting distance INF INF INF D6 52.257 112.894 139.015 D10 7.479 9.827 9.196 D16 99.620 39.887 1.598 D24 10.634 7.382 20.181 D28 5.669 12.009 5.884 D32 29.429 23.088 29.214

[0149] [Table 4] f 205.426 447.698 774.302 Shooting distance 2900.00 2900.00 2900.00 D28 6.790 17.652 22.535 D32 28.308 17.445 12.562

[0150] [Table 5] Group Surface number Focal length G1 1-6 271.689 G2 7-10 -157.925 G3 11-16 -129.552 G4 17-24 76.819 G5 25-28 139.408 G6 29-32 -80.182 G7 33-51 -115.240

[0151] 2 to 4 show longitudinal aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. The longitudinal aberration diagrams shown in each diagram are, from the left side of the drawing, spherical aberration (mm), astigmatism (mm), and distortion (%), respectively. In the diagrams showing spherical aberration, the vertical axis shows the ratio to the open F-number, the horizontal axis shows defocus, the solid line shows spherical aberration at the d-line (wavelength λ=587.6 nm), the dashed and dotted line shows spherical aberration at the g-line (wavelength λ=435.8 nm), and the dotted line shows spherical aberration at the C-line (wavelength λ=656.3 nm). In the diagrams showing astigmatism, the vertical axis shows image height, the horizontal axis shows defocus, the solid line shows the sagittal image plane (ds) for the d-line, and the dotted line shows the meridional image plane (dm) for the d-line. In the diagrams showing distortion, the vertical axis represents image height and the horizontal axis represents %, and distortion is shown in %. The matters relating to these longitudinal aberration diagrams are the same as those shown in the longitudinal aberration diagrams of other embodiments, so the explanation will be omitted below.

[0152] The back focus "BFw" of the zoom lens at the wide-angle end when focusing on infinity is as follows: Note that the following value does not include the cover glass (Nd=1.5168), and the back focus shown in the other examples is the same. BFw = 56.1827 (mm) EXAMPLES

[0153] (1) Optical configuration of zoom lens FIG. 5 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 2 according to the present invention at the wide-angle end when focusing on infinity. The zoom lens is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power. The aperture stop S is disposed on the object side of the sixth lens group G6. In this example, the rear group is composed of the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The lens group Gp having positive refractive power is the third lens group G3. The rear group is composed of an object side group Rfn and an image side group Rrp. In this embodiment, the object side group Rfn is composed of the second lens group G2, and the image side group Rrp is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.

[0154] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2 are cemented together, and a positive meniscus lens L3 with a convex shape toward the object side. The biconvex lens L2 is the lens L1p1 referred to in the present invention, and the positive meniscus lens L3 with a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 with a convex shape toward the object side is the lens L1n referred to in the present invention. Among the lenses with positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is the lens L3. The ΔPgF of the lens L3 is 0.0375. The average linear expansion coefficient α1n of the lens L1 is 71×10 -7 / °C, and the average linear expansion coefficient α1p of the lens L2 is 93×10 -7 / ℃.

[0155] The second lens group G2 is composed of, in order from the object side, a cemented lens in which a biconvex lens L4 and a biconcave lens L5 are cemented together, a cemented lens in which a biconcave lens L6 and a biconvex lens L7 are cemented together, and a biconcave lens L8.

[0156] The third lens group G3 is composed of, in order from the object side, a biconvex lens L9, a biconvex lens L10, and a cemented lens in which a biconvex lens L11 and a biconcave lens L12 are cemented together. The biconcave lens L12 is the lens Lpn and also the lens Lnr referred to in the present invention. The biconvex lens L9 and the biconvex lens L10 are the lens Lrp referred to in the present invention, and ΔPgFLrp of each is 0.0375.

[0157] The fourth lens group G4 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape facing the object side and a biconvex lens L14 are cemented together. The negative meniscus lens L13 having a convex shape facing the object side is the lens Lnr referred to in the present invention.

[0158] The fifth lens group G5 is composed of a cemented lens in which a convex lens L15 and a biconcave lens L16 are cemented together.

[0159] The sixth lens group G6 is composed of, in order from the object side, an aperture stop S, a cemented lens formed by cementing a negative meniscus lens L17 having a convex shape toward the object side and a biconvex lens L18, a cemented lens formed by cementing a convex lens L19 and a biconcave lens L20, a cemented lens formed by cementing a biconvex lens L21 and a biconcave lens L22, a lens L23 which is a parallel plate having no substantial refractive power, and a cemented lens formed by cementing a biconvex lens L24 and a biconcave lens L25. The lens L23 is an insert filter.

[0160] In the zoom lens of Example 2, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction relative to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves so as to draw a convex locus toward the image side, the fourth lens group G4 is fixed in the optical axis direction, the fifth lens group G5 moves so as to draw a convex locus toward the image side, and the sixth lens group G6 is fixed in the optical axis direction.

[0161] In this embodiment, the fifth lens group G5 is moved relative to the fourth lens group G4 in a manner that traces a convex path toward the image side when changing magnification from the wide-angle end to the telephoto end, thereby ensuring good image surface quality at intermediate focal lengths.

[0162] Furthermore, in this embodiment, it is preferable that a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 serves as an image vibration isolation group, and that the image is shifted when camera shake or the like occurs by moving this image vibration isolation group in a direction perpendicular to the optical axis, thereby correcting image blur.

[0163] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. Table 6 shows the surface data of the zoom lens, and Table 7 shows the specifications of the zoom lens. Note that the 46th and 47th surfaces in Table 6 are surface data of the insert filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

[0164] Table 8 shows the variable distances on the optical axis of the zoom lens when changing magnification, and Table 9 shows the variable distances on the optical axis of the zoom lens when focusing. Note that Table 9 shows values ​​when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance for each focal length.

[0165] Table 10 shows the focal length of each lens group constituting the zoom lens. Table 21 shows the values ​​of conditional expressions (1) to (12) and the values ​​used in the calculation of conditional expressions (1) to (12).

[0166] 6 to 8 show longitudinal aberration diagrams of the zoom lens of Example 2 at the wide-angle end, in the intermediate focal length state, and at the telephoto end when focusing on infinity, respectively.

[0167] Furthermore, the back focus of the zoom lens when focused at infinity at the wide-angle end is as follows: BFw = 47.6948 (mm)

[0168] [Table 6] Surface number rd Nd vd H 1 362.2289 3.100 1.80610 33.27 51.958 2 148.7380 0.020 1.56732 42.84 51.152 3 148.7380 11.943 1.48749 70.24 51.151 4 -839.0352 0.320 51.100 5 120.7253 11.492 1.49700 81.61 50.672 6 1035.1075 D6 50.403 7 1612.3555 4.355 1.80518 25.46 23.500 8 -99.7929 0.010 1.56732 42.84 23.330 9 -99.7929 1.690 1.72916 54.67 23.328 10 80.4516 5.860 22.294 11 -285.4912 1.710 1.63289 34.54 22.245 12 64.7661 0.010 1.56732 42.84 22.351 13 64.7661 4.944 1.84666 23.78 22.351 14 -401.8539 2,300 22,343 15 -94.2412 1.635 1.81681 31.34 22.321 16 254.1913 D16 22.641 17 160.3987 6.213 1.49700 81.61 24.316 18 -92.2467 0.199 24.300 19 101.0736 5.040 1.49700 81.61 24.116 20 -312.5122 0.200 23.997 21 63.5833 7.594 1.48749 70.44 22.960 22 -105.1497 0.010 1.56732 42.84 22.754 23 -105.1497 1.625 1.84441 38.49 22.752 24 167.7347 D24 21.895 25 65.5436 1.300 1.91082 35.25 20.152 26 37.1386 0.010 1.56732 42.84 19.252 27 37.1386 6.491 1.69130 58.05 19.251 28 920.1015 D28 18.970 29 -559.2891 2.610 1.84666 23.78 15.059 30 -121.5774 0.010 1.56732 42.84 14.701 31 -121.5774 1.000 1.72916 54.67 14.698 32 58.3442 D32 13.952 33 S 0.0000 1.707 10.100 34 153.8780 1.000 1.90366 31.31 9.816 35 34.1694 0.010 1.56732 42.84 9.601 36 34.1694 4.330 1.61866 39.21 9.601 37 -47.7062 5.016 9.500 38 -908.6427 3.262 1.71048 29.60 9.888 39 -38.3253 0.010 1.56732 42.84 9.808 40 -38.3253 0.830 1.72916 54.67 9.807 41 34.3612 4.757 9.682 42 91.8992 4.358 1.59300 39.20 9.784 43 -25.5977 0.010 1.56732 42.84 9.885 44 -25.5977 0.920 1.83911 39.33 9.885 45 560.4082 10.773 10.191 46 0.0000 2.000 1.51680 64.20 12.395 47 0.0000 11.904 12.664 48 43.3914 5.980 1.55911 47.43 15.730 49 -68.4700 0.010 1.56732 42.84 15.712 50 -68.4700 1.020 1.74891 48.93 15.712 51 115.5809 45.376 15.760 52 0.0000 2.000 1.51680 64.20 21.371 53 0.0000 1.000 21.540

[0169] [Table 7] f 204.385 383.887 583.896 F no. 5.704 5.705 5.706 ω 6.042 3.209 2.103 Y 21.633 21.633 21.633 TL 354.884 354.884 354.884

[0170] [Table 8] f 204.385 383.887 583.896 Photographic distance INF INF INF D6 56.409 98.944 116.672 D16 71.977 33.155 7.621 D24 7.185 3.472 11.277 D28 6.430 10.735 6.553 D32 24.426 20.120 24.302

[0171] [Table 9] f 204.385 383.887 583.896 Shooting distance 2500.00 2500.00 2500.00 D28 7.981 16.488 19.715 D32 22.874 14.368 11.140

[0172] [Table 10] Group Surface number Focal length G1 1-6 232.198 G2 7-16 -57.984 G3 17-24 66.335 G4 25-28 136.607 G5 29-32 -76.491 G6 33-51 -100.196 EXAMPLES

[0173] (1) Optical configuration of zoom lens 9 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 3 according to the present invention at the wide-angle end when focusing on infinity. The zoom lens is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power. The aperture stop S is disposed on the object side of the sixth lens group G6. In this example, the rear group is composed of the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The lens group Gp having positive refractive power is the third lens group G3. The rear group is composed of an object side group Rfn and an image side group Rrp. In this embodiment, the object side group Rfn is composed of the second lens group G2, and the image side group Rrp is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6.

[0174] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2 are cemented together, and a positive meniscus lens L3 with a convex shape toward the object side. The biconvex lens L2 is the lens L1p1 referred to in the present invention, and the positive meniscus lens L3 with a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 with a convex shape toward the object side is the lens L1n referred to in the present invention. Among the lenses with positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is the lens L3. The ΔPgF of the lens L3 is 0.0375. The average linear expansion coefficient α1n of the lens L1 is 71×10 -7 / °C, and the average linear expansion coefficient α1p of the lens L2 is 93×10 -7 / ℃.

[0175] The second lens group G2 is composed of, in order from the object side, a cemented lens in which a convex lens L4 and a biconcave lens L5 are cemented together, a cemented lens in which a biconcave lens L6 and a biconvex lens L7 are cemented together, and a biconcave lens L8.

[0176] The third lens group G3 is composed of, in order from the object side, a biconvex lens L9, a biconvex lens L10, and a cemented lens in which a biconvex lens L11 and a biconcave lens L12 are cemented together. The biconcave lens L12 is the lens Lpn and also the lens Lnr referred to in the present invention. The biconvex lens L9 and the biconvex lens L10 are the lens Lrp referred to in the present invention, and ΔPgFLrp is 0.0375.

[0177] The fourth lens group G4 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape facing the object side and a biconvex lens L14 are cemented together. The negative meniscus lens L13 having a convex shape facing the object side is the lens Lnr referred to in the present invention.

[0178] The fifth lens group G5 is composed of a cemented lens in which a convex lens L15 and a biconcave lens L16 are cemented together.

[0179] The sixth lens group G6 is composed of, in order from the object side, an aperture stop S, a cemented lens formed by cementing a negative meniscus lens L17 having a convex shape toward the object side and a biconvex lens L18, a cemented lens formed by cementing a convex lens L19 and a biconcave lens L20, a cemented lens formed by cementing a biconvex lens L21 and a biconcave lens L22, a lens L23 which is a parallel plate having no substantial refractive power, and a cemented lens formed by cementing a biconvex lens L24 and a biconcave lens L25. The lens L23 is an insert filter.

[0180] In the zoom lens of Example 3, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction relative to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves so as to draw a convex locus toward the image side, the fourth lens group G4 is fixed in the optical axis direction, the fifth lens group G5 moves so as to draw a convex locus toward the image side, and the sixth lens group G6 is fixed in the optical axis direction.

[0181] In this embodiment, the fifth lens group G5 is moved relative to the fourth lens group G4 in a manner that traces a convex path toward the image side when changing magnification from the wide-angle end to the telephoto end, thereby ensuring good image surface quality at intermediate focal lengths.

[0182] Furthermore, in this embodiment, it is preferable that a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 serves as an image vibration isolation group, and that the image is shifted when camera shake or the like occurs by moving this image vibration isolation group in a direction perpendicular to the optical axis, thereby correcting image blur.

[0183] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. Table 11 shows the surface data of the zoom lens, and Table 12 shows the specifications of the zoom lens. Note that the 46th and 47th surfaces in Table 11 are surface data of the insert filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

[0184] Table 13 shows the variable distances on the optical axis of the zoom lens when changing magnification, and Table 14 shows the variable distances on the optical axis of the zoom lens when focusing. Note that Table 14 shows values ​​when the shooting distance (imaging distance) is 2900.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance for each focal length.

[0185] Table 15 shows the focal length of each lens group constituting the zoom lens. Table 21 shows the values ​​of each of the conditional expressions (1) to (12) and the values ​​used in the calculation of the conditional expressions (1) to (12).

[0186] 10 to 12 respectively show longitudinal aberration diagrams of the zoom lens of Example 2 at the wide-angle end, in the intermediate focal length state, and at the telephoto end when focusing on infinity.

[0187] Furthermore, the back focus of the zoom lens when focused at infinity at the wide-angle end is as follows: BFw = 56.1739 (mm)

[0188] [Table 11] Surface number rd Nd vd H 1 490.3765 3.600 1.80610 33.27 58.980 2 184.2738 0.020 1.56732 42.84 58.307 3 184.2738 13.847 1.48749 70.24 58.306 4 -644.4705 0.380 58.280 5 140.7126 13.392 1.49700 81.61 57.695 6 939.9051 D6 57.226 7 -6546.1557 4.880 1.80518 25.46 25.940 8 -110.5280 0.010 1.56732 42.84 25.674 9 -110.5280 2.000 1.72916 54.67 25.672 10 93.6214 6.805 24.532 11 -513.3426 1.990 1.60809 37.31 24.421 12 76.2026 0.010 1.56732 42.84 24.405 13 76.2026 5.400 1.84634 23.01 24.405 14 -1152.8990 2.923 24.361 15 -118.3850 1.980 1.80547 29.17 24.302 16 286.0255 D16 24.547 17 190.3131 6.978 1.49700 81.61 24.883 18 -103.8327 0.400 25.010 19 127.3893 5.649 1.49700 81.61 24.939 20 -294.3761 0.300 24.781 21 70.3951 8.680 1.49700 81.61 23.924 22 -110.6908 0.010 1.56732 42.84 23.487 23 -110.6908 2.190 1.84436 41.63 23.485 24 162.0783 D24 22.642 25 70.0851 1.500 1.83989 39.26 19.931 26 38.8848 0.010 1.56732 42.84 19.184 27 38.8848 7.263 1.64015 60.53 19.182 28 -667.4123 D28 18.868 29 -311.8794 3.248 1.84424 22.96 15.019 30 -93.9273 0.010 1.56732 42.84 14.653 31 -93.9273 1.000 1.72916 54.67 14.651 32 68.6275 D32 14.038 33 S 0.0000 2.000 10.080 34 392.0022 1.110 1.90366 31.31 10.801 35 38.9125 0.010 1.56732 42.84 10.672 36 38.9125 5.115 1.63937 44.56 10.672 37 -48.0465 5.794 9.500 38 -1713.1103 3.698 1.70543 29.72 10.419 39 -40.4444 0.010 1.56732 42.84 10.274 40 -40.4444 1.022 1.72916 54.67 10.273 41 38.8273 5.437 10.067 42 66.4117 5.050 1.60318 36.97 10.216 43 -28.8650 0.010 1.56732 42.84 10.247 44 -28.8650 1.011 1.83884 39.38 10.247 45 117.8452 14.524 10.447 46 0.0000 2.000 1.51680 64.20 13.096 47 0.0000 12.217 13.342 48 50.9026 6.810 1.56076 46.20 16.139 49 -57.5740 0.010 1.56732 42.84 16.130 50 -57.5740 1.200 1.73758 49.76 16.130 51 223.3820 53.855 16.232 52 0.0000 2.000 1.51680 64.20 21.464 53 0.0000 1.000 21.595

[0189] [Table 12] f 205.696 449.061 775.202 Fno. 6.602 6.605 6.597 ω 6.000 2.747 1.584 Y 21.633 21.633 21.633 TL 415.203 415.203 415.203

[0190] [Table 13] f 205.696 449.061 775.202 Shooting distance INF INF INF D6 51.903 113.643 140.873 D16 98.741 40.130 1.635 D24 11.823 8.694 19.959 D28 5.108 11.101 5.562 D32 29.271 23.278 28.817

[0191] [Table 14] f 205.696 449.061 775.202 Shooting distance 2900.00 2900.00 2900.00 D28 6.235 16.761 22.294 D32 28.145 17.618 12.086

[0192] [Table 15] Group Surface number Focal length G1 1-6 271.026 G2 7-16 -67.309 G3 17-24 79.310 G4 25-28 127.916 G5 29-32 -82.233 G6 33-51 -110.211 EXAMPLES

[0193] (1) Optical configuration of zoom lens 13 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 4 according to the present invention at the wide-angle end when focusing on infinity. The zoom lens is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having negative refractive power. When focusing from an object at infinity to a close object, the sixth lens group G6 moves toward the image side along the optical axis. The aperture stop S is disposed on the object side of the seventh lens group G7. In this example, the rear group is composed of the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7. The lens group Gp having positive refractive power is the fourth lens group G4. The rear group is composed of an object side group Rfn and an image side group Rrp. In this embodiment, the object side group Rfn is composed of the second lens group G2. The image side group Rrp is composed of the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7.

[0194] The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2 are cemented together, and a positive meniscus lens L3 with a convex shape toward the object side. The biconvex lens L2 is the lens L1p1 referred to in the present invention, and the positive meniscus lens L3 with a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 with a convex shape toward the object side is the lens L1n referred to in the present invention. Among the lenses with positive refractive power included in the first lens group, the lens with the largest anomalous dispersion is the lens L3. The ΔPgF of the lens L3 is 0.0375. The average linear expansion coefficient α1n of the lens L1 is 70×10 -7 / °C, and the average linear expansion coefficient α1p of the lens L2 is 93×10 -7 / ℃.

[0195] The second lens group G2 is composed of, in order from the object side, a cemented lens in which a convex lens L4 and a biconcave lens L5 are cemented together, a cemented lens in which a biconcave lens L6 and a biconvex lens L7 are cemented together, and a biconcave lens L8.

[0196] The third lens group G3 is composed of a biconvex lens L9. The biconvex lens L9 is the lens Lrp referred to in the present invention, and ΔPgFLrp is 0.0564.

[0197] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L10 and a cemented lens in which a biconvex lens L11 and a biconcave lens L12 are cemented together. The biconcave lens L12 is the lens Lpn and also the lens Lnr referred to in the present invention. The biconvex lens L10 is the lens Lrp referred to in the present invention, and ΔPgFLrp is 0.0375.

[0198] The fifth lens group G5 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape facing the object side and a biconvex lens L14 are cemented together. The negative meniscus lens L13 having a convex shape facing the object side is the lens Lnr referred to in the present invention.

[0199] The sixth lens group G6 is composed of a cemented lens in which a convex lens L15 and a biconcave lens L16 are cemented together.

[0200] The seventh lens group G7 is composed of, in order from the object side, an aperture stop S, a cemented lens formed by cementing a negative meniscus lens L17 having a convex shape facing the object side and a biconvex lens L18, a cemented lens formed by cementing a convex lens L19 and a biconcave lens L20, a cemented lens formed by cementing a biconvex lens L21 and a biconcave lens L22, a lens L23 which is a parallel plate having no substantial refractive power, and a cemented lens formed by cementing a biconvex lens L24 and a biconcave lens L25. The lens L23 is an insert filter.

[0201] In the zoom lens of Example 4, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction relative to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves so as to draw a convex locus toward the image side, the fourth lens group G4 moves so as to draw a convex locus toward the image side, the fifth lens group G5 is fixed in the optical axis direction, the sixth lens group G6 moves so as to draw a convex locus toward the image side, and the seventh lens group G7 is fixed in the optical axis direction.

[0202] In this embodiment, the sixth lens group G6 is moved relative to the fifth lens group G5 in a manner that traces a convex path toward the image side when changing magnification from the wide-angle end to the telephoto end, thereby ensuring good image surface quality at intermediate focal lengths.

[0203] Furthermore, in this embodiment, it is preferable that a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 serves as an image vibration isolation group, and that the image is shifted when camera shake or the like occurs by moving this image vibration isolation group in a direction perpendicular to the optical axis, thereby correcting image blur.

[0204] (2) Numerical examples Next, a numerical example in which specific numerical values ​​of the zoom lens are applied will be described. Table 16 shows the surface data of the zoom lens, and Table 21 shows the specifications of the zoom lens. Note that the 46th and 47th surfaces in Table 16 are surface data of the insert filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

[0205] Table 18 shows the variable distances on the optical axis of the zoom lens when changing magnification, and Table 19 shows the variable distances on the optical axis of the zoom lens when focusing. Note that Table 14 shows values ​​when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance for each focal length.

[0206] Table 20 shows the focal length of each lens group constituting the zoom lens, and Table 21 shows the values ​​of conditional expressions (1) to (12) and the values ​​used in the calculation of conditional expressions (1) to (12).

[0207] 14 to 16 respectively show longitudinal aberration diagrams of the zoom lens of Example 4 at the wide-angle end, in the intermediate focal length state, and at the telephoto end when focusing on infinity.

[0208] Furthermore, the back focus of the zoom lens when focused at infinity at the wide-angle end is as follows: BFw = 48.0568(mm)

[0209] [Table 16] Surface number rd Nd vd H 1 264.1633 3.100 1.90366 31.31 52.227 2 142.7348 0.020 1.56732 42.84 51.301 3 142.7348 12.042 1.48749 70.44 51.300 4 -1997.6032 0.320 51.200 5 120.4876 11.567 1.49700 81.61 50.739 6 1069.9965 D6 50.466 7 269.4881 4.607 1.80518 25.46 23.000 8 -119.6669 0.010 1.56732 42.84 22.776 9 -119.6669 1.700 1.72916 54.67 22.774 10 75.5414 6.000 21.562 11 -205.3696 1.670 1.62488 35.68 21.419 12 74.7690 0.010 1.56732 42.84 21.361 13 74.7690 4.967 1.84666 23.78 21.361 14 -715.1550 2.294 21.294 15 -95.6404 1.650 1.81278 33.47 21.271 16 217.6991 D16 21.497 17 157.0424 6.416 1.43700 95.10 22.722 18 -84.7937 D18 22.700 19 106.5878 5.040 1.49700 81.61 22.666 20 -282.5029 0.198 22.544 21 73.9929 7.470 1.48749 70.44 21.888 22 -98.0726 0.010 1.56732 42.84 21.534 23 -98.0726 1.450 1.83937 39.30 21.532 24 244.9626 D24 20.989 25 55.4224 1.300 1.91082 35.25 19.223 26 33.4857 0.010 1.56732 42.84 18.338 27 33.4857 6.762 1.68788 57.00 18.337 28 586.3403 D28 17.993 29 -308.0756 2.437 1.84666 23.78 13.697 30 -89.2090 0.010 1.56732 42.84 13.402 31 -89.2090 1.000 1.72916 54.67 13.400 32 48.3414 D32 12.688 33 S 0.0000 1.707 9.970 34 121.4146 1.000 1.90366 31.31 9.758 35 32.8275 0.010 1.56732 42.84 9.572 36 32.8275 4.540 1.61783 46.59 9.572 37 -45.7069 4.851 9.500 38 -556.3160 ​​3.186 1.72235 28.80 10.102 39 -39.2740 0.010 1.56732 42.84 10.057 40 -39.2740 0.800 1.72916 54.67 10.056 41 39.7894 4.670 9.983 42 81.5025 4.457 1.60002 38.95 10.015 43 -30.7098 0.010 1.56732 42.84 10.116 44 -30.7098 0.950 1.82894 40.51 10.117 45 445.2750 10.828 10.352 46 0.0000 2.000 1.51680 64.20 12.240 47 0.0000 11.790 12.470 48 40.3649 5.980 1.55831 45.30 15.062 49 -88.2563 0.010 1.56732 42.84 14.998 50 -88.2563 1.020 1.74557 49.66 14.997 51 68.8837 45.738 14.943 52 0.0000 2.000 1.51680 64.20 21.348 53 0.0000 1.000 21.538

[0210] [Table 17] f 204.246 382.296 585.319 Fno 5.746 5.742 5.742 ω 6.019 3.209 2.087 Y 21.633 21.633 21.633 TL 354.681 354.681 354.681

[0211] [Table 18] f 204.246 382.296 585.319 Shooting distance INF INF INF D6 56.622 97.755 114.578 D16 68.724 31.508 5.951 D18 0.643 2.436 1.341 D24 9.515 3.805 13.633 D28 7.247 10.642 6.283 D32 23.312 19.918 24.276

[0212] [Table 19] f 204.246 382.296 585.319 Shooting distance 2500.00 2500.00 2500.00 D28 8.692 15.838 18.342 D32 21.867 14.722 12.218

[0213] [Table 20] Group Surface number Focal length G1 1-6 227.064 G2 7-16 -56.326 G3 17-18 127.027 G4 19-24 154.913 G5 25-28 114.458 G5 29-32 -60.325 G6 33-51 -160.070

[0214] [Table 21] Example 1 Example 2 Example 3 Example 4 Conditional expression (1) ft / fnot / Y 5.438 4.730 5.432 4.712 Conditional expression (2) νdL1p1 70.240 70.240 70.240 70.440 Conditional expression (3) νdLpn 40.810 38.490 41.627 39.300 Conditional expression (4) f1 / ft 0.351 0.398 0.350 0.388 Conditional expression (5) βRT 1.899 1.821 1.948 1.392 Conditional expression (6) βnRT 4.199 3.862 4.215 3.801 Conditional expression (7) NdL1n 1.806 1.806 1.806 1.904 Conditional expression (8) ΔPgFLrp 0.038 0.038 0.038 0.056 Conditional expression (9) f1 / fw 1.323 1.136 1.318 1.112 Condition (10) NdLnr 1.911 1.911 1.844 1.839 Conditional expression (11) BFw / (fw×tanωw) 2.599 2.205 2.598 2.232 Conditional expression (12) Lt / ft 0.536 0.608 0.536 0.606 ft 774.302 583.896 775.202 585.319 fw 205.426 204.385 205.696 204.246 fnot 6.583 5.706 6.597 5.742 Y 21.633 21.633 21.633 21.633 f1 271.689 232.198 271.026 227.064 BFw 56.183 47.695 56.174 48.057 ω 6.008 6.042 6.000 6.019 Lt 415.348 354.884 415.203 354.681 [Industrial Applicability]

[0215] According to the present invention, it is possible to provide a zoom lens and an imaging device that are small, lightweight, and have high optical performance. [Explanation of symbols]

[0216] G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: 6th lens group G7: 7th lens group S Aperture CG ···Cover glass IMG...Image plane

Claims

1. The zoom lens is made up of, in order from the object side, a first lens group having positive refractive power and a rear group including at least one lens group Gp having positive refractive power, and changes the air space between adjacent lens groups to change the magnification. the first lens group includes a lens L1p1 having a positive refractive power, and the number of lenses having a positive refractive power included in the first lens group is two or less; The lens group Gp includes a lens Lpn having a negative refractive power, the rear group has a lens having a positive refractive power located closest to the object, a focus group which is one of the lens groups constituting the rear group or a part thereof; the rear group includes at least one lens Lnr having negative refractive power, the rear group has a vibration reduction group that corrects image blur by moving in a direction perpendicular to the optical axis, The number of focus groups is only one, A zoom lens characterized by satisfying the following conditional expressions: 3.50 < ft / fnot / Y < 9.00...(1) 63.0 < νdL1p1 < 76.0 (2) 38.0 < νdLpn < 65.0 (3) 1.91082≦NdLnr<2.20 (10) 1.80 < BFw / (fw×tanωw) < 3.20 (11) however, ft: focal length of the zoom lens at the telephoto end fnot: F-number of the zoom lens at the telephoto end Y: Maximum image height of the zoom lens νdL1p1: Abbe number at the d line of the lens L1p1 νdLpn: Abbe number at d line of the lens Lpn NdLnr: refractive index of the lens Lnr at the d line BFw: the air equivalent length at the wide-angle end of the zoom lens from the lens surface closest to the image side to the image plane fw: focal length of the zoom lens at the wide-angle end ωw: Half angle of view of the most off-axis chief ray of the zoom lens when focused at infinity at the wide-angle end

2. The zoom lens is made up of, in order from the object side, a first lens group having positive refractive power and a rear group including at least one lens group Gp having positive refractive power, and changes the air space between adjacent lens groups to change the magnification. the first lens group includes a lens L1p1 having a positive refractive power, and the number of lenses having a positive refractive power included in the first lens group is two or less; the lens group Gp is ​​disposed closest to the object side among the lens groups having positive refractive power included in the rear group, The lens group Gp includes a lens Lpn having a negative refractive power, the rear group has a lens having a positive refractive power located closest to the object, the rear group includes at least one lens Lnr having negative refractive power, the rear group has a vibration reduction group that corrects image blur by moving in a direction perpendicular to the optical axis, A zoom lens characterized by satisfying the following conditional expressions: 63.0 < νdL1p1 < 76.0 (2) 38.0 < νdLpn < 65.0 (3) 1.91082≦NdLnr<2.20 (10) however, νdL1p1: Abbe number at the d line of the lens L1p1 νdLpn: Abbe number at d line of the lens Lpn NdLnr: refractive index of the lens Lnr at the d line

3. 3. The zoom lens according to claim 1, which satisfies the following condition: 0.25 < f1 / ft < 0.65 (4) however, f1: focal length of the first lens group ft: focal length of the zoom lens at the telephoto end

4. 4. The zoom lens according to claim 1, further comprising a stop on the image side of the lens group Gp.

5. 5. The zoom lens according to claim 1, wherein the rear group includes at least one lens Lrp having a positive refractive power, and the following condition is satisfied: 1<Lrp<1 / 2. 0.010 < ΔPgFLrp < 0.070 (8) however, ΔPgFLrp: anomalous dispersion of the lens having the largest anomalous dispersion among the lenses Lrp included in the rear group. Here, anomalous dispersion refers to the deviation of the partial dispersion ratio from a reference line when a straight line passing through the partial dispersion ratios and the coordinates of νd of C7 (partial dispersion ratio: 0.5393, νd: 60.49) and F2 (partial dispersion ratio: 0.5829, νd: 36.30) is used as the reference line.

6. 6. The zoom lens according to claim 1, which satisfies the following condition: 0.80 < f1 / fw < 3.00 (9) however, f1: focal length of the first lens group fw: focal length of the zoom lens at the wide-angle end

7. 7. The zoom lens according to claim 1, which satisfies the following condition: 0.40 < Lt / ft < 0.75 (12) however, Lt: the distance from the lens surface closest to the object of the zoom lens at the telephoto end to the image plane ft: focal length of the zoom lens at the telephoto end

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

Images