Zoom lens and imaging 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 sophisticated, leading to a rapid spread of compact imaging systems. Furthermore, there is a particularly strong demand for compact, high-performance optical systems for telephoto zoom lenses with long focal lengths.

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

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-126850 Summary of the Invention [Problem to be solved by the invention]

[0005] The zoom lens disclosed in Patent Document 1 achieves high optical performance by using a positive lens made of a glass material with anomalous dispersion in the first lens group. 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 telephoto zoom lenses, the lenses in the first lens group have large diameters, and positive lenses are thick. Furthermore, glass materials with anomalous dispersion are expensive and have a high specific gravity. Therefore, if a positive lens with anomalous dispersion is included in the first lens group, the cost and weight increase. Furthermore, if the first lens group becomes heavy, the drive mechanism for moving the first lens group along the optical axis during magnification change also becomes large, which increases the size and weight of the entire zoom lens unit.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a zoom lens and an imaging device that are small, lightweight, and have high optical performance. [Means for solving the problem]

[0007] In order to solve the above problems, a zoom lens according to the present invention comprises, 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, wherein magnification is changed by changing the air spacing 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, and the lens group Gp includes a lens Lpn having negative refractive power, the rear group has a lens element having positive refractive power closest to the object, a focus group that is one of the lens groups that make up the rear group or a part of the lens group; the rear group includes at least one lens Lnr having negative refractive power, the rear group has an image stabilization 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 by satisfying the following conditional expression. 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 the 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 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 problem, a zoom lens according to the present invention comprises, 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 zoom lens performs magnification by changing the air spacing 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 ​​located closest to the object 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 element having positive refractive power closest to the object, the rear group includes at least one lens Lnr having negative refractive power, the rear group has an image stabilization group that corrects image blur by moving in a direction perpendicular to the optical axis, It is characterized by satisfying the following conditional expression. 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 the d line of the lens Lpn NdLnr: refractive index at d line of the lens Lnr

[0008] In addition, in order to solve the above problem, the imaging device of the present invention is characterized by comprising the above zoom lens and an imaging element on the image side of the zoom lens that converts the optical image formed by the zoom lens into an electrical signal. [Effects 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 explanation 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. [Figure 2] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 at the wide-angle end when focused on infinity. [Figure 3] 3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 when focused on infinity in an intermediate focal length state. [Figure 4]3A to 3C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 1 at the telephoto end when focused on infinity. [Figure 5] 10 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] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity at the wide-angle end. [Figure 7] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity in an intermediate focal length state. [Figure 8] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 2 when focused on infinity at the telephoto end. [Figure 9] 10 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] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on infinity at the wide-angle end. [Figure 11] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on infinity in an intermediate focal length state. [Figure 12] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 3 when focused on 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] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity at the wide-angle end. [Figure 15] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity in an intermediate focal length state. [Figure 16] 10A to 10C are diagrams illustrating spherical aberration, astigmatism, and distortion of the zoom lens of Example 4 when focused on infinity at the telephoto end. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes an embodiment of a zoom lens and an imaging device according to the present invention. However, the zoom lens and imaging device described below are one aspect of the zoom lens and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following aspects.

[0012] 1. Zoom Lens 1-1.Optical structure of a zoom lens The zoom lens of this embodiment is composed of, from the object side, a first lens group having positive refractive power and a rear lens group. By adopting a power arrangement in which positive refractive power is positioned closest to the object side of the zoom lens, the maximum height of axial rays can be reduced, thereby facilitating radial miniaturization of the zoom lens. In particular, since the lenses constituting the first lens group can be easily miniaturized 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 diameters of the lenses constituting the other lens groups. By miniaturizing the radial direction of the first lens group, the effect of miniaturizing and lightweighting the entire zoom lens is significant. This effect is particularly pronounced when this power arrangement is adopted in a zoom lens whose zoom range includes a focal length longer than 100 mm (35mm equivalent) and whose entrance pupil diameter at the telephoto end is greater than 80 mm.

[0013] Furthermore, in this zoom lens, the diameter of the light beam incident on the rear group is smaller than the diameter of the light beam incident on the first lens group. Therefore, when the focus group or the vibration-reduction group is located in the rear group, the focus group or the vibration-reduction group can be made smaller and lighter than when the focus group or the vibration-reduction group is located in the first lens group. The optical configuration of each lens group will be described below. Note that the zoom lens may essentially consist of the first lens group and the rear group. That is, in addition to the lens groups described below, optical elements with no or very little refractive power may be located. 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. There are no particular limitations on the specific lens configuration of the first lens group, as long as it has positive refractive power as a whole.

[0015] Since the first lens group has positive refractive power as a whole, it includes at least one lens with positive refractive power. That is, the lens L1p1 may be the only lens with positive refractive power included in the first lens group. However, to effectively correct chromatic aberration and spherical aberration at the telephoto end, it is preferable that the first lens group include a lens L1p2 with positive refractive power in addition to the lens L1p1. By increasing the number of lenses with positive refractive power included in the first lens group, it is possible to allocate strong positive refractive power to the first lens group while suppressing spherical aberration and other aberrations by adjusting the shape of each surface, thereby achieving a zoom lens with high optical performance. However, the first lens group is composed of the lens with the largest diameter in the zoom lens. Therefore, increasing the number of lenses included in the first lens group increases the weight of the zoom lens. 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 that the first lens group includes at least one lens L1n having negative refractive power, in order to correct chromatic aberration and improve image plane characteristics.

[0017] For these reasons, it is more preferable to configure the first lens group with a total of three lenses, that is, 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 negative refractive power, the lens L1n is preferably cemented with the lens L1p1 or lens L1p2. By cementing the lens L1n having negative refractive power with a lens having positive refractive power (lens L1p1 or lens L1p2), various manufacturing errors, such as decentering errors and errors in the air gap between individual lenses, can be reduced compared to when these lenses are arranged with an air gap between them. This reduces the degradation of optical performance due to manufacturing errors, and reduces variations in performance between products. Therefore, by cementing the lens L1n having negative refractive power with a lens having positive refractive power (lens L1p1 or lens L1p2), zoom lenses with high optical performance can be manufactured with a high yield.

[0019] Incidentally, if there is a difference in the linear expansion coefficients of the glass materials of the lenses cemented together, the glass materials will expand or contract in different ways as the ambient temperature changes, causing different shape changes and imposing stress on the cemented surface. The larger the diameter of the lenses constituting the cemented lens, the greater the stress imposed on the cemented surface due to the difference in the linear expansion coefficients of the glass materials, causing problems such as cracking or breaking of the cemented lens at the cemented surface. If there is a large difference in the linear expansion coefficients of the lenses constituting the cemented lens, 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, this phenomenon is more likely to occur in the cemented lens arranged in the first lens group than in the other lens groups. Therefore, when the rate of change in sample length 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 sample length 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 disposed 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 having positive refractive power included in the first lens group (lens L1p1 or lens L1p2) 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] Furthermore, from the viewpoint of correcting chromatic aberration, it is preferable that at least one of the lenses having positive refractive power in the first lens group (lens L1p1 or lens L1p2) be made of a glass material with high anomalous dispersion. In particular, it is preferable that at least one of the lenses having positive refractive power in the first lens group (lens L1p1 or lens L1p2) have an anomalous dispersion (ΔPgF) greater than 0.015, more preferably greater than 0.019, and even more preferably greater than 0.025. The anomalous dispersion (ΔPgF) refers to the deviation of the partial dispersion ratio from a reference line, where the reference line is a line passing through the coordinates of the partial dispersion ratios and νd of C7 (partial dispersion ratio: 0.5393, νd: 60.49) and F2 (partial dispersion ratio: 0.5829, νd: 36.30).

[0022] Since glass materials with high anomalous dispersion have a relatively high specific gravity, when the first lens group includes two lenses with positive refractive power (lens L1p1, lens L1p2), it is preferable for the high performance and light weight of the zoom lens that one of the lenses be made of a glass material with high anomalous dispersion and the other lens be 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 multiple lens groups arranged closer to the image than the first lens group. The rear group includes a lens group Gp having positive refractive power. The configuration of the other lens groups in the rear group is not particularly limited as long as it includes the lens group Gp having positive refractive power. For example, the rear group may include two or more lens groups having positive refractive power, or one or more lens groups having negative refractive power. Furthermore, if the refractive power of the rear group as a whole is negative at the telephoto end, this results in a refractive power arrangement that has a strong telephoto tendency. This effectively reduces the overall optical length of the zoom lens at the telephoto end relative to the focal length, which is preferable for achieving a compact zoom lens. However, the overall refractive power of the rear group at the telephoto end may be negative or positive, and the sign of the overall refractive power of the rear group is not particularly limited. A strong telephoto tendency means a small telephoto ratio (L / f, where L is the overall optical length and f is the focal length).

[0024] (a) Object-side group Rfn and image-side group Rrp It is preferable that the rear group include an object-side group Rfn that includes at least one lens group and has negative refractive power overall, located closer to the object than the largest air gap at the wide-angle end, and an image-side group Rrp that includes at least one lens group and has positive refractive power overall, located closer to the image than the largest air gap at the wide-angle end. By adopting a refractive power arrangement in the rear group in which the object-side group Rfn that has negative refractive power overall is located closer to the object than the largest air gap at the wide-angle end, and the image-side group Rrp that has positive refractive power overall is located on the image side thereof, a large combined lateral magnification can be ensured by the object-side group Rfn, 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 with negative refractive power, or one or more lens groups with 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 include at least one lens group with 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 be arranged within the image-side group Rrp.

[0027] Furthermore, it is preferable that the lens group Gp having positive refractive power includes 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 within the first lens group. Therefore, chromatic aberration occurring in the first lens group must be corrected in the rear group. Therefore, by arranging a lens Lpn having negative refractive power in the lens group Gp having positive refractive power arranged in the rear group, axial chromatic aberration can be effectively corrected, which is preferable in terms of improving the performance of the zoom lens.

[0028] (c) Lens group with negative refractive power Furthermore, it is preferable that the rear group includes a lens group having negative refractive power. When varying magnification, it is preferable to move the lens group having negative refractive power arranged in the rear group toward the image side, since this increases the focal length of the zoom lens at the telephoto end. However, if there are multiple lens groups having negative refractive power arranged in the rear group, it is sufficient to move at least one lens group toward the image side. Furthermore, it is preferable that the lens group having negative refractive power moved toward the image side is the object-side group Rfn. By moving the lens group having negative refractive power arranged in the rear group toward the image side, the lateral magnification of the lens group having negative refractive power at the telephoto end can be increased. This makes it possible to increase the focal length of the zoom lens at the telephoto end while maintaining its compact size.

[0029] Furthermore, in order to improve image surface quality at intermediate focal lengths, it is preferable to move the lens group with negative refractive power located in the rear group along a locus convex toward the image side. If there are multiple lens groups with negative refractive power located 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 with negative refractive power included in the rear group, the lens group with negative refractive power that is located closest to the image is designated 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 negative lens group n is preferably located closer to the object than lens group R.

[0031] (d) Lens group R Here, the lens group in the rear group that is positioned closest to the image 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 other than lens group Gp having positive refractive power. Lens group R may also be a lens group having negative refractive power.

[0032] In order to reduce the overall optical length of the zoom lens at the telephoto end, it is preferable that the lens group R has negative refractive power. By adopting a telephoto-type refractive power arrangement in which positive refractive power is arranged on the object side and 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 negative refractive power, a refractive power arrangement with a strong telephoto-type tendency can be adopted, which is preferable in terms of reducing the overall optical length 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] Furthermore, in order to further improve the performance of the zoom lens, it is preferable that the rear group includes at least one lens Lnr having negative refractive power. By arranging the lens Lnr having negative refractive power in the rear group, it is possible to improve the image plane characteristics and reduce chromatic aberration.

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

[0036] Here, in telephoto zoom lenses with long focal lengths, the pupil diameter becomes large. Typically, ND filters, PL filters, and the like are positioned closest to the object in the optical system. However, in telephoto zoom lenses with focal lengths exceeding 500 mm at the telephoto end in 35mm format, for example, the diameter of the first lens group becomes large, and commercially available filters corresponding to such diameters may not exist. It is preferable that such a zoom lens unit be configured so that such filters can be inserted into the rear group. In this case, it is preferable that the filter be fixed relative to the image plane during zooming.

[0037] (3) Focus group The zoom lens may or may not have a focus group. When focusing, it is sufficient to move at least one lens in the zoom lens in the optical axis direction, and the position and refractive power of that lens are not particularly limited.

[0038] Although the first lens group or a portion thereof may be used as the focus group, it is more preferable to use one or a portion of the lens groups constituting the rear group as the focus group. The lens groups constituting the rear group have a smaller diameter than the first lens group, which is preferable for reducing the size and weight of the focus group. Furthermore, reducing the size and weight of the focus group also reduces the size and weight of the drive mechanism for moving the focus group along the optical axis during focusing (hereinafter referred to as the focus drive mechanism). This is preferable because it allows for the overall size of the zoom lens unit, including the lens barrel portion of the zoom lens, to be reduced. It should be noted that the zoom lens unit includes, in addition to the focus drive mechanism, a zoom drive mechanism for moving each lens group relative to one another during zooming, as well as a lens barrel accommodating these mechanisms.

[0039] Furthermore, 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 be composed of one single lens unit. Here, a single lens unit refers to a lens unit such as a single lens or a cemented lens in which multiple single lenses are integrated without any air gap. In other words, even if a single lens unit has multiple optical surfaces, only the most object-side and most image-side surfaces 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. Furthermore, an aspherical lens is also considered to include a so-called composite aspherical lens in which an aspherical film is attached to the surface.

[0041] When the focus group is configured from the single lens unit, there is no air gap in the focus group. Therefore, compared to a configuration in which multiple single lenses are arranged with air gaps between them, configuring the focus group from a single lens unit allows for a smaller and lighter focus group. 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 spacing between the single lenses can be reduced compared to a configuration in which the focus group is configured with multiple single lenses arranged with air gaps between them. This makes it possible to reduce the degradation of optical performance caused by manufacturing errors and reduce variations 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 either positive or negative refractive power. When the focus group has negative refractive power, the lateral magnification of the focus group can be increased compared to when the focus group has positive refractive power, resulting in increased focus sensitivity and a reduced focus movement amount, which is preferable for achieving a compact zoom lens. The direction of movement of the focus group during focusing is not particularly limited, but when the focus group has negative refractive power, it is preferable to move the focus group toward the image side when focusing from infinity to a close subject. It is particularly preferable that the focus group be the negative lens group n described above.

[0044] The lens surfaces included in the focus group may be entirely spherical or may include aspherical surfaces. Using only spherical surfaces in the focus group is preferable because it reduces costs. On the other hand, if at least one of the lens surfaces included in the focus group is aspherical, it is possible to configure a focus group with less aberration fluctuation during focusing using a smaller number of lenses, thereby enabling the overall size of the zoom lens unit, including the focus drive mechanism. In this case, it is preferable that the aspherical 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 aspherical surface with such a shape in the focus group, spherical aberration, coma, and field curvature during focusing can be corrected, thereby achieving a zoom lens with higher optical performance throughout the entire focusing range.

[0045] Furthermore, if a focus group is provided in the rear group, it is preferable that the focus group be located closer to the object than the lens group R, which is located closest to the image. A flexible substrate or the like, equipped with a control circuit and the like for electrically connecting the zoom lens to the image capture device body, is located closest to the image side of the zoom lens. Therefore, if the lens group R or a part of it is used as the focus group, it is difficult to secure space within the lens barrel for arranging the various mechanical components that make up the focus drive mechanism, which would require a larger lens barrel diameter, making it difficult to construct a compact zoom lens. By arranging the focus group closer to the object than the lens group R, it becomes easier to secure space for arranging the various mechanical components that make up the focus drive mechanism, allowing for a smaller lens barrel diameter and therefore a more compact zoom lens unit overall.

[0046] When a focus group is provided in the rear group, it is preferable that the focus group be located on the image side of the lens group having positive refractive power. By locating 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 incident on the focus group, thereby making it possible to reduce the diameter of the focus group. Furthermore, by reducing the diameter of the focus group, it is possible to reduce the weight of the focus group, which is preferable because it allows the entire zoom lens unit to be made smaller.

[0047] In this zoom lens, multiple lens groups or a portion of multiple lens groups may be used as the focus group. That is, focusing may be performed using a floating system. By adopting a floating system, spherical aberration and image plane characteristics can be improved at closer focusing, which is preferable in terms of improving performance.

[0048] (4) Aperture diaphragm In this zoom lens, the location of the aperture diaphragm is not particularly limited, but it is preferable to place the aperture diaphragm within the rear group in order to make the diaphragm unit more compact. 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, as well as mechanical components 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 positive refractive power enters the rear group. Therefore, the diameter of the light beam incident on the rear group is smaller than the diameter of the light beam incident on the first lens group. Therefore, by placing the aperture diaphragm in the rear group, the aperture diameter can be reduced. Furthermore, if the aperture diaphragm is placed closer to the image side than the lens group Gp having positive refractive power in the rear group, the lens group Gp can further converge the incident light beam, which is preferable for reducing the diameter of the aperture diaphragm and reducing the size of the aperture unit.

[0050] Furthermore, if the lens group R in the rear group, which is positioned closest to the image side, is fixed relative to the image plane during magnification variation, it is preferable to provide an aperture diaphragm on the object side of the lens group R or within the lens group R. If the lens group R is fixed relative to the image plane during magnification variation, the magnification of the lens group R does not change, and therefore it is not necessary to change the aperture diameter of the aperture diaphragm during magnification variation. This allows the F-number of the zoom lens to be constant during magnification variation.

[0051] (5) Anti-vibration group The presence or absence of an image stabilization group in the zoom lens 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, thereby correcting image blur caused by camera shake or the like.

[0052] When such an image stabilization group is provided in the zoom lens, there are no particular limitations on the location of the image stabilization group, but providing the image stabilization group within the rear group is preferable in order to reduce the diameter of the image stabilization 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 image stabilization group in the rear group, it is possible to reduce the size and weight of the image stabilization group compared to when the image stabilization group is provided in the front group.

[0053] It is also preferable to position the vibration-reduction group closer to the image side than the aperture stop. Because the fluctuation in ray height during magnification is small on the image side of the aperture stop, the fluctuation in aberration during magnification is also small. Therefore, it is possible to reduce the fluctuation in aberration during vibration reduction, and high optical performance can be maintained even during vibration reduction. Furthermore, by positioning the vibration-reduction group closer to the image side than the aperture stop, it is possible to reduce the amount of movement of the vibration-reduction group when correcting image blur with the vibration-reduction group. This allows for the size of the vibration-reduction unit, and therefore the size of the entire zoom lens unit.

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

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

[0056] It is more preferable that the vibration isolation group be composed of one lens having negative refractive power and one lens having 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, thereby reducing the size of the vibration isolation unit and the size of the entire zoom lens unit.

[0057] When the image stabilization group is composed of one lens having negative refractive power and one lens having positive refractive power, it is preferable that these two lenses are cemented together. That is, it is preferable that the image stabilization group is composed of a single lens unit in which a lens having negative refractive power and a lens having positive refractive power are cemented together. By constructing the image stabilization group from a single lens unit, it is possible to achieve a smaller size than a configuration in which a lens having negative refractive power and a lens having 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 errors in the air gap between the single lenses. This reduces the degradation of optical performance caused by manufacturing errors and reduces performance variations between products. Therefore, it is possible to manufacture zoom lenses with high optical performance with a high yield.

[0058] Furthermore, when the zoom lens is provided with an image stabilization group, the lens surfaces included in the image stabilization group may be spherical or may include aspherical surfaces. In terms of reducing costs, it is preferable that all of the lens surfaces included in the image stabilization group are spherical.

[0059] On the other hand, if at least one of the lens surfaces included in the image stabilization group is aspherical, it becomes easier to satisfy the optical performance required of the zoom lens even when the image stabilization group is configured with a small number of lenses. This allows the image stabilization group to be configured with a small number of lenses, thereby enabling the image stabilization group to be made smaller and lighter. In this case, it is preferable that the aspherical 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 aspherical surface with such a shape in the image stabilization group, coma aberration and one-sided blur caused by decentering can be corrected, thereby realizing a zoom lens with even higher optical performance.

[0060] The vibration-reduction group is preferably a lens group or part thereof that is fixed in the optical axis direction relative to the image plane during zooming. To move the vibration-reduction group in a direction perpendicular to the optical axis during vibration reduction, a flexible substrate is provided on which mechanical components for driving the vibration-reduction group and electronic circuits for controlling them are mounted. If the vibration-reduction group moves in the optical axis direction during zooming, it is difficult to secure space to accommodate the flexible substrate, etc., making it difficult to achieve a compact zoom lens unit overall. Furthermore, if the flexible substrate is bent and arranged within the lens barrel, the vibration-reduction group may become decentered due to a reaction force from the flexible substrate, which may degrade the optical performance of the zoom lens, which is undesirable.

[0061] In the rear group, when the lens group R located closest to the image has negative refractive power, it is preferable to use this lens group R or a part of it as an image stabilization group. As mentioned above, when lens group R has negative refractive power, the zoom lens has a refractive power arrangement that is more likely to be a telephoto type, and the diameter of lens group R can also be reduced. Therefore, if an image stabilization group is located in 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 part of the lens group R is used as a vibration reduction group, it is preferable that at least one lens be arranged on the image side of the vibration reduction lens group. Furthermore, it is preferable that the composite focal length of all lenses arranged on the image side of the vibration reduction group be negative. By arranging a lens with negative refractive power on the image side of the vibration reduction group, it is possible to increase the image compensation coefficient of the vibration reduction group, i.e., the amount of image plane movement per unit movement of the vibration reduction group, and therefore the amount of movement of the vibration reduction group during vibration reduction can be reduced, making it easier to reduce the size of the vibration reduction unit.

[0063] (7) Lens group configuration The number of lens groups constituting the zoom lens is not particularly limited, and various lens group configurations can be used, 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, or 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 has, in order from the object side, a first lens group having positive refractive power and a rear group.

[0064] 1-2. Operation when changing magnification In the zoom lens, the air spacing between adjacent lens groups is changed when changing magnification from the wide-angle end to the telephoto end. It is also preferable that the air spacing 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 with positive refractive power and may include other lens groups. If the rear group includes multiple lens groups, the air spacing between adjacent lens groups within the rear group also changes. As long as the air spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end, there are no particular limitations on the increase or decrease in the air spacing between each lens group. Increasing the air spacing between the first lens group and the lens group in the rear group closest to the object is preferable for achieving a high zoom ratio, but there are no particular limitations on the increase or decrease in the air spacing between the other lens groups. Furthermore, during zooming, all of the lens groups constituting the zoom lens may move along the optical axis, or some lens groups may be fixed along the optical axis and the remaining lens groups may move along the optical axis. The presence or absence of movement of each lens group and the direction of movement are not particularly limited.

[0066] In a large zoom lens with a long focal length, such as one with an entrance pupil diameter exceeding 80 mm, the weight of the first lens group exceeds several hundred grams. To accurately move such a heavy lens group to a predetermined position during zooming, a large load is placed on the mechanical components that drive the first lens group, and the mechanical structure that controls the zoom lens's operation during zooming is also large. Therefore, in order to achieve a compact and lightweight zoom lens unit, it is preferable to fix the first lens group, which is positioned closest to the object, in the optical axis direction relative to the image plane during zooming. Furthermore, fixing the first lens group relative to the image plane reduces movement of the center of gravity, 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 when changing magnification, there is no change in the lens barrel length, which makes it easier to make at least the object side of the lens barrel watertight, making it easier to prevent dust and moisture from entering the lens barrel from the object side, which is preferable.

[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 zooming, 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, as mentioned above, by making the lens group R a fixed group, it is possible to reduce the diameter of the lens barrel.

[0069] 1-3.Conditional Expressions In this zoom lens, it is preferable that the above-mentioned configuration be adopted and that one or more of the following conditional expressions be 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 expression (1) defines the size of the entrance pupil diameter. By satisfying conditional expression (1), the entrance pupil diameter becomes an appropriate size. As a result, the diameter of the first lens group can be prevented from increasing while achieving a telephoto zoom of the zoom lens, and the weight of the zoom lens can be reduced.

[0072] On the other hand, if the value of conditional formula (1) exceeds 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 value of conditional formula (1) falls below the lower limit, it becomes difficult to achieve a telephoto zoom with the zoom lens, which is undesirable.

[0073] 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, and 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 effectively corrected, and a zoom lens with high optical performance can be realized while also being lightweight.

[0076] On the other hand, if the value of conditional formula (2) is equal to or greater than the upper limit, the Abbe number of lens L1p1 at the d-line becomes large. Glass materials with large Abbe numbers tend to have high specific gravity. Furthermore, the first lens group is composed of lenses with larger diameters 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, if 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, if 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 makes it difficult to realize a zoom lens with high optical performance, which is undesirable.

[0077] To obtain the above effects, the lower limit of conditional formula (2) is more preferably 64.0, even more preferably 66.0, and even more preferably 68.0, and 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] Conditional formula (3) 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, chromatic aberration occurring in the first lens group will be insufficiently corrected. Therefore, the chromatic aberration that cannot be sufficiently corrected in the first lens group needs to be corrected in the rear group. To reduce the weight of the first lens group, it is effective to use a glass material with a low specific gravity for the lens having positive refractive power included in the first lens group. In this case, by using a glass material that satisfies conditional formula (3) for the lens Lpn having negative refractive power arranged in the lens group Gp having positive refractive power in the rear group, axial chromatic aberration can be effectively corrected, resulting in a zoom lens with high optical performance and reduced weight.

[0080] On the other hand, if the value of conditional expression (3) is equal to or greater than the upper limit, the Abbe number of the lens Lpn at the d-line becomes large. In this case, the correction of axial chromatic aberration becomes insufficient. On the other hand, if the value of conditional expression (3) is equal to or less than the lower limit, the Abbe number of the lens Lpn at the d-line becomes small. In this 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] 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, and 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) defines 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 compact zoom lens with high optical performance.

[0084] On the other hand, if the value of conditional expression (4) is below the lower limit, the refractive power of the first lens group becomes too strong, resulting in large spherical aberration and large curvature of field at the telephoto end. Correcting this requires increasing the number of lenses for aberration correction, which makes it difficult to realize a compact, lightweight zoom lens with high optical performance, which is undesirable. Also, if the value of conditional expression (4) is above the upper limit, the refractive power of the first lens group becomes too weak. This makes it difficult to shorten the overall optical length of the zoom lens at the telephoto end, which makes it difficult to achieve a compact zoom lens, which is undesirable.

[0085] In order to obtain the above-mentioned 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, and 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 expression (5) defines the lateral magnification of the lens unit R in the rear group, which is located closest to the image. Satisfying conditional expression (5) allows for a refractive power arrangement with a strong telephoto tendency, 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, if the value of conditional formula (5) is below the lower limit, the lateral magnification of the lens group R becomes small, weakening the tendency for telephoto shooting. This makes it difficult to shorten the overall optical length at the telephoto end relative to the focal length, making it difficult to miniaturize the zoom lens, which is undesirable. On the other hand, if the value of conditional formula (5) is above the upper limit, the lateral magnification of the lens group R becomes large, increasing the effect of magnifying various aberrations. This makes it difficult to correct aberrations at the telephoto end, and in order to achieve a zoom lens with high optical performance, it is necessary to increase the number of lenses for aberration correction. This makes it difficult to achieve a zoom lens with high optical performance that is both compact and lightweight, which is undesirable.

[0089] To obtain the above effects, the lower limit of conditional formula (5) is more preferably 1.25, even more preferably 1.30, still more preferably 1.35, even more preferably 1.40, and even more preferably 1.45, while 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: Combined lateral magnification at the telephoto end from negative lens unit n to lens unit R

[0091] Conditional expression (6) defines the composite lateral magnification at the telephoto end of the lens located closer to the image than the negative lens group n. As mentioned above, the negative lens group n refers to the lens group with negative refractive power that is located closest to the image among the lens groups with negative refractive power included in the rear group. By satisfying conditional expression (6), a refractive power arrangement with a stronger telephoto tendency can be achieved, and the overall optical length at the telephoto end can be made shorter compared to the focal length, making it easier to reduce the size of the zoom lens.

[0092] On the other hand, if the value of conditional formula (6) is below the lower limit, the combined lateral magnification at the telephoto end due to the lens groups arranged after the negative lens group n becomes small, weakening the tendency for telephoto shooting. This makes it difficult to shorten the overall optical length at the telephoto end relative to the focal length, making it difficult to miniaturize the zoom lens, which is undesirable. Also, if the value of conditional formula (6) is above the upper limit, the combined lateral magnification at the telephoto end due to the lens groups arranged after the negative lens group n becomes large, increasing the effect of magnifying various aberrations. This makes it difficult to correct aberrations at the telephoto end, and in order to achieve a zoom lens with high optical performance, it is necessary to increase the number of lenses for aberration correction. This makes it difficult to achieve a zoom lens with high optical performance that is both compact and lightweight, 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, and 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 of lens L1n at the d line

[0095] Conditional expression (7) defines the refractive index at the d-line of the lens L1n having negative refractive power included in the first lens group. In a lens group having positive refractive power, Petzval's sum is typically corrected by using a high-refractive-index glass material for the lens having negative refractive power and a low-refractive-index glass material for the lens having positive refractive power. However, because high-refractive-index glass materials are expensive, if the refractive index of lens L1n is too high, it becomes difficult to construct the zoom lens at low cost. Furthermore, because high-refractive-index glass materials have a high specific gravity, they are undesirable in terms of reducing the weight of the zoom lens. By satisfying conditional expression (7), it is possible to reduce the cost and weight of the zoom lens while maintaining good image plane characteristics.

[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, making it difficult to correct for image plane distortion, which is undesirable. 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 are expensive and tend to have 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 chromatic aberration of magnification, 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 effect, it is more preferable that the lower limit of conditional expression (7) be 1.80, and it is more preferable that the upper limit 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 greatest 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 νd coordinates 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) defines the anomalous dispersion of lens Lrp when the rear group includes at least one lens Lrp with positive refractive power. Generally, chromatic aberrations are corrected by using a high-dispersion glass material for the lens with negative refractive power and a low-dispersion glass material for the lens with positive refractive power. However, the refractive index of high-dispersion glass materials changes in a positive quadratic curve from short to long wavelengths across a wide visible range, whereas the refractive index of low-dispersion glass materials changes linearly. Therefore, even when these two lenses are combined, it is difficult to adequately correct chromatic aberrations across the entire wavelength range. On the other hand, lenses made of glass materials with positive anomalous dispersion have a refractive index that changes in a positive quadratic curve from short to long wavelengths, similar to high-dispersion glass materials. Therefore, using a lens with positive refractive power made of glass materials with positive anomalous dispersion facilitates adequate correction of chromatic aberrations 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 effectively, making it easier to realize a zoom lens that has high optical performance over the entire magnification range.

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

[0102] To obtain the above effects, the lower limit of conditional expression (8) is more preferably 0.015, even 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 expression (8) is more preferably 0.065, and even more preferably 0.060.

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

[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) defines 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 easier to reduce the size of the zoom lens at the wide-angle end and achieving a zoom lens with high optical performance.

[0106] On the other hand, if the value of conditional expression (9) is below the lower limit, the refractive power of the first lens group becomes too strong, resulting in a large amount of curvature of field at the wide-angle end. This results in a decrease in optical performance at the wide-angle end, which is undesirable. On the other hand, if the value of conditional expression (9) is above the upper limit, the refractive power of the first lens group becomes too weak. This results in a long overall optical length at the wide-angle end, which is undesirable from the perspective of compactness.

[0107] In order to obtain the above-mentioned 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, and 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 expression (10) defines the refractive index at the d-line of the lens Lnr having negative refractive power included in the rear group. As mentioned above, it is common to correct the Petzval sum by using a high-refractive-index glass material for the lens having negative refractive power and a low-refractive-index glass material for the lens having positive refractive power. However, because high-refractive-index glass materials are expensive, if the refractive index of the lens Lnr is too high, it becomes difficult to construct the zoom lens at low cost. Furthermore, because high-refractive-index glass materials have a high specific gravity, they are undesirable in terms of reducing the weight of the zoom lens. Satisfying conditional expression (10) ensures good image plane characteristics and enables the zoom lens to be made at low cost and lightweight.

[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, making it difficult to correct the image plane, which is undesirable. 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 a plurality of lenses Lnr having negative refractive power, it is sufficient that one of the lenses Lnr satisfies conditional expression (10). Any of the lenses Lnr having negative refractive power included in the rear group may satisfy conditional expression (10).

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

[0113] Furthermore, in order to reduce the Petzval sum of a lens group having positive refractive power, it is necessary that the negative lens included in that lens group 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) be included in the lens group having positive refractive power in the rear group.

[0114] 1-3-11.Conditional Expression (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 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) defines the ratio between the back focal length at the wide-angle end of the zoom lens and the maximum image height on the image plane. By satisfying conditional expression (11), a compact zoom lens can be realized while ensuring a back focal length at the wide-angle end that is suitable for an interchangeable lens.

[0116] On the other hand, if the value of conditional expression (11) is equal to or less than the lower limit, i.e., if the back focal length becomes too short relative to the maximum image height, it becomes difficult to ensure a back focal length suitable for an interchangeable lens at the wide-angle end, which is undesirable.Also, if the value of conditional expression (11) is equal to or greater than the upper limit, i.e., if the back focal length becomes long relative to the maximum image height, it becomes difficult to achieve a compact zoom lens at the wide-angle end, which is undesirable.

[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, and 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) defines 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, making it possible to realize a zoom lens that is short in total optical length compared to the focal length, is compact, lightweight, and has high optical performance.

[0120] On the other hand, if the value of conditional expression (12) is below 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 effectively correct various aberrations at the telephoto end, resulting in a deterioration in optical performance. Furthermore, error sensitivity increases, which significantly reduces the degradation of optical performance due to manufacturing errors and results in a large variation in performance between products. On the other hand, if the value of conditional expression (12) is above the upper limit, i.e., if the total optical length at the telephoto end is too long compared to the focal length, the amount of movement of each lens group during zooming increases to achieve a predetermined zoom ratio, which in turn results in an increase in the size of the 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 expression (12) is more preferably 0.42, even more preferably 0.45, even more preferably 0.48, and even more preferably 0.51. The upper limit of conditional expression (12) is more preferably 0.72, even more preferably 0.70, even more preferably 0.68, even more preferably 0.66, and even more preferably 0.64.

[0122] 2. Imaging device Next, we will explain the imaging device of the present invention, which is characterized by including the zoom lens of the present invention described above and an imaging element provided on the image plane side of the zoom lens, which converts 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 CCD (Charge Coupled Device) sensors and CMOS (Complementary Metal Oxide Semiconductor) sensors can also be used. The imaging device of the present invention is suitable for imaging devices using such solid-state imaging elements, such as digital cameras and video cameras. The imaging device may also be a fixed-lens imaging device in which the lens is fixed to the housing, or an interchangeable-lens imaging device such as a single-lens reflex camera or a mirrorless single-lens camera. In particular, the zoom lens of 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 viewfinder, a phase difference sensor, a reflex mirror for splitting light to these, etc.

[0124] The imaging device preferably includes an image processing unit that electrically processes captured image data acquired by the imaging element to change the shape of the captured image, and an image correction data storage unit that stores image correction data, an image correction program, etc., used to process the captured image data in the image processing unit. When a zoom lens is made smaller, distortion (curvature) of the captured image formed on the imaging plane is likely to occur. In this case, it is preferable to store distortion correction data in advance in the image correction data storage unit for correcting the distortion of the captured image shape, and for the image processing unit to correct the distortion of the captured image shape using the distortion correction data stored in the image correction data storage unit. Such an imaging device allows for even smaller zoom lenses, resulting in clearer captured images and a more compact imaging device overall.

[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 corrects the magnification chromatic aberration 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, using 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, thereby obtaining beautiful captured images and reducing the size of the entire imaging device.

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

[0127] (1) Optical structure of the zoom lens FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention, showing the lens configuration at the wide-angle end when focusing at 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 located on the object side of the seventh lens group G7. In this embodiment, 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 formed by cementing together a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2, 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. Of the lenses with positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is lens L3. The ΔPgF of lens L3 is 0.0375. The mean linear expansion coefficient α1n of 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 surface facing the object side and a biconvex lens L14 are cemented together. The negative meniscus lens L13 having a convex surface 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 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 a filter such as an ND filter or PL filter. The filter is insertable into the zoom lens unit from the outside of the lens barrel. This filter is an optional component in the zoom lens of the present invention. In the following, in other embodiments, filters similar to this filter will be referred to as "insertable filters."

[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 describe 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 describe a convex locus toward the image side, and the seventh lens group G7 is fixed in the optical axis direction.

[0136] Here, if the lens group having negative refractive power among the lens groups included in the rear group is moved relative to the object-side lens group so as to trace a convex path toward the image side when changing magnification from the wide-angle end to the telephoto end, image surface quality at intermediate focal lengths is improved. In this embodiment, the sixth lens group G6 is moved relative to the fifth lens group G5 so as to trace 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. In addition, in this embodiment, the sixth lens group G6 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] Furthermore, 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, it is preferable to use a cemented lens formed by cementing together a convex lens L19 and a biconcave lens L20 included in the seventh lens group G7 as an image stabilization group, and to correct image blur by shifting the image when camera shake or the like occurs by moving this image stabilization group in a direction perpendicular to the optical axis.

[0138] Furthermore, "IMG" in Figure 1 denotes an image plane, specifically the imaging surface of a solid-state imaging device such as a CCD sensor or a CMOS sensor, or the film surface of a silver halide film. A parallel plate with 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 other embodiments, and therefore will not be described below.

[0139] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values ​​of this zoom lens. Table 1 shows the surface data of this zoom lens. In Table 1, the "surface number" indicates the order of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the axial spacing of the lens surface, "Nd" indicates the refractive index for the d-line (wavelength λ=587.6 nm), "vd" indicates the Abbe number for the d-line, and "H" indicates the effective radius. The "S" displayed in the column next to the surface number represents the aperture stop. Furthermore, "D6," "D16," etc., in the column for the axial spacing of lens surfaces indicate that the axial spacing of the lens surfaces is a variable spacing that changes during magnification or focusing. Note that all length units in each table are "mm," and all angle of view units are "°." Note that "0.0000" for the radius of curvature indicates a flat surface. Note that surfaces 46 and 47 in Table 1 represent surface data for the insert filter, and surfaces 52 and 53 represent surface data for the cover glass CG.

[0140] Table 2 shows the specifications of this zoom lens. The specifications show 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, Table 2 shows the respective values ​​at the wide-angle end, mid-focal length state, and telephoto end, from left to right.

[0141] Table 3 shows the variable spacing on the optical axis of the zoom lens when changing magnification. Starting from the left, Table 3 shows the values ​​at the wide-angle end, at the mid-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 distances 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, mid-focal length state, and 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 makes up the zoom lens.

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

[0145] The matters relating to these tables are the same as those in the tables shown in the other embodiments, and therefore, explanations thereof 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, from left to right, show spherical aberration (mm), astigmatism (mm), and distortion (%), respectively. In the diagrams showing spherical aberration, the vertical axis represents the ratio to the maximum aperture F-number, and the horizontal axis represents defocus. The solid line represents spherical aberration at the d-line (wavelength λ=587.6 nm), the dashed-dotted line represents spherical aberration at the g-line (wavelength λ=435.8 nm), and the dotted line represents spherical aberration at the C-line (wavelength λ=656.3 nm). In the diagrams showing astigmatism, the vertical axis represents image height, the horizontal axis represents defocus, and the solid line represents the sagittal image plane (ds) relative to the d-line, and the dotted line represents the meridional image plane (dm) relative to the d-line. In the diagrams showing distortion, the vertical axis represents image height and the horizontal axis represents distortion in %. The matters relating to these longitudinal aberration diagrams are the same as those shown in the longitudinal aberration diagrams of other examples, and therefore will not be described below.

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

[0153] (1) Optical structure of the zoom lens FIG. 5 is a cross-sectional view showing the lens configuration of a zoom lens according to Example 2 of the present invention at the wide-angle end when focusing at infinity. This 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. An aperture stop S is located 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 made up of the second lens group G2, and the image-side group Rrp is made up 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 formed by cementing a negative meniscus lens L1 with a convex shape toward the object side and a biconvex lens L2, 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. Of the lenses with positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is lens L3. The ΔPgF of lens L3 is 0.0375. The mean linear expansion coefficient α1n of 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 formed by cementing a biconvex lens L4 and a biconcave lens L5, a cemented lens formed by cementing a biconcave lens L6 and a biconvex lens L7, 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 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 and the biconvex lens L10 are the lens Lrp referred to in the present invention, and ΔPgFLrp for each is 0.0375.

[0157] The fourth lens group G4 is composed of a cemented lens formed by cementing together a negative meniscus lens L13 having a convex surface facing the object side and a biconvex lens L14. The negative meniscus lens L13 having a convex surface 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 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.

[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 to describe 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 to describe 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 plane characteristics at intermediate focal lengths.

[0162] In this embodiment, it is preferable that the sixth lens group G6 includes a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20, and that the vibration-reduction group be moved in a direction perpendicular to the optical axis to shift the image when camera shake or the like occurs, thereby correcting image blur.

[0163] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values ​​of the zoom lens. Table 6 shows the surface data of the zoom lens, and Table 7 shows the specifications of the zoom lens. Note that in Table 6, surfaces 46 and 47 are surface data of the insert filter, and surfaces 52 and 53 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. Table 9 also shows values ​​when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, mid-focal length state, and telephoto end. This value is the shortest imaging distance for each focal length.

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

[0173] (1) Optical structure of the zoom lens FIG. 9 is a cross-sectional view showing the lens configuration of a zoom lens according to Example 3 of the present invention at the wide-angle end when focusing at 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. An aperture stop S is located 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 made up of the second lens group G2, and the image-side group Rrp is made up 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 formed by cementing a negative meniscus lens L1 having a convex shape toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having 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 having a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 having a convex shape toward the object side is the lens L1n referred to in the present invention. Of the lenses having positive refractive power included in the first lens group G1, the lens with the largest anomalous dispersion is lens L3. The ΔPgF of lens L3 is 0.0375. The mean linear expansion coefficient α1n of 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 formed by cementing a convex lens L4 and a biconcave lens L5, a cemented lens formed by cementing a biconcave lens L6 and a biconvex lens L7, 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 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 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 formed by cementing together a negative meniscus lens L13 having a convex surface facing the object side and a biconvex lens L14. The negative meniscus lens L13 having a convex surface 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 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.

[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 to describe 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 to describe 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 plane characteristics at intermediate focal lengths.

[0182] In this embodiment, it is preferable that the sixth lens group G6 includes a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20, and that the vibration-reduction group be moved in a direction perpendicular to the optical axis to shift the image when camera shake or the like occurs, thereby correcting image blur.

[0183] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values ​​of the zoom lens. Table 11 shows the surface data of the zoom lens, and Table 12 shows the specifications of the zoom lens. Note that in Table 11, surfaces 46 and 47 are surface data of the insert filter, and surfaces 52 and 53 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. Table 14 also shows values ​​when the shooting distance (imaging distance) is 2900.00 mm at the wide-angle end, mid-focal length state, and telephoto end. This value is the shortest imaging distance for each focal length.

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

[0186] 10 to 12 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.

[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 [Example]

[0193] (1) Optical structure of the zoom lens FIG. 13 is a cross-sectional view showing the lens configuration of a zoom lens according to Example 4 of the present invention at the wide-angle end when focusing on infinity. This 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. An aperture stop S is located 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 explained below. The first lens group G1 is composed of, in order from the object side, a cemented lens formed by cementing a negative meniscus lens L1 having a convex shape toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having 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 having a convex shape toward the object side is the lens L1p2 referred to in the present invention. The negative meniscus lens L1 having a convex shape toward the object side is the lens L1n referred to in the present invention. Of the lenses having positive refractive power included in the first lens group, the lens with the largest anomalous dispersion is lens L3. The ΔPgF of lens L3 is 0.0375. The mean linear expansion coefficient α1n of 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 formed by cementing a convex lens L4 and a biconcave lens L5, a cemented lens formed by cementing a biconcave lens L6 and a biconvex lens L7, 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 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 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 formed by cementing together a negative meniscus lens L13 having a convex surface facing the object side and a biconvex lens L14. The negative meniscus lens L13 having a convex surface 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 moves 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 plane characteristics at intermediate focal lengths.

[0203] In this embodiment, it is preferable that the sixth lens group G6 includes a cemented lens formed by cementing together the convex lens L19 and the biconcave lens L20, and that the vibration-reduction group be moved in a direction perpendicular to the optical axis to shift the image when camera shake or the like occurs, thereby correcting image blur.

[0204] (2) Numerical examples Next, we will explain numerical examples that apply specific numerical values ​​of the zoom lens. Table 16 shows the surface data of the zoom lens, and Table 21 shows the specifications of the zoom lens. Note that in Table 16, surfaces 46 and 47 are surface data of the insert filter, and surfaces 52 and 53 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. Table 14 shows values ​​when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, mid-focal length state, and telephoto end. This value is the shortest imaging distance for each focal length.

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

[0207] 14 to 16 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, respectively.

[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 ωw 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 lens 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 spacing between adjacent lens groups; 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 element having positive refractive power closest to the object, The rear lens group includes only one lens group or a focus group that is a part of the lens group, the rear group has at least one lens Lnr having negative refractive power, A zoom lens characterized by satisfying the following conditional expression: 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 the 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 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 lens 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 spacing between adjacent lens groups; 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 ​​located 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 element having positive refractive power closest to the object, the rear group has at least one lens Lnr having negative refractive power, A zoom lens characterized by satisfying the following conditional expression: 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 the 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, wherein the following condition is satisfied: 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. 3. The zoom lens according to claim 2, wherein the rear group has a lens unit R closest to the image side, the lens unit R having negative refractive power.

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

6. 6. The zoom lens according to claim 1, wherein the first lens group includes a lens L1n having negative refractive power, and the following condition is satisfied: 1.79 < NdL1n < 1.92 (7) however, NdL1n: refractive index of the lens L1n at the d line

7. 7. 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. 0.010 < ΔPgFLrp < 0.070 (8) however, ΔPgFLrp: anomalous dispersion of the lens with 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 line passing through the partial dispersion ratios and the vd coordinates of C7 (partial dispersion ratio: 0.5393, vd: 60.49) and F2 (partial dispersion ratio: 0.5829, vd: 36.30) is used as the reference line.

8. 8. The zoom lens according to claim 1, wherein the following condition is satisfied: 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

9. 9. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.40 < Lt / ft < 0.75 (12) however, Lt: 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

10. 10. An imaging device comprising: the zoom lens according to claim 1; and an image sensor on the image side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal.

Images