JP2020106777A - Zoom lens and image capturing device - Google Patents

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

The present invention relates to a zoom lens and an imaging device, and particularly to a zoom lens and an imaging device suitable for an imaging optical system of an imaging device using a solid-state imaging device or the like.

2. Description of the Related Art In recent years, image pickup apparatuses using solid-state image pickup devices such as digital still cameras and digital video cameras have become widespread. Along with this, the performance and size of the optical system of these image pickup devices have been improved, and small image pickup device systems have been rapidly spread. Further, in a telephoto zoom lens having a long focal length, there is a particularly strong demand for miniaturization as well as high performance of the optical system.

Therefore, Patent Document 1 proposes a zoom lens in which the zoom ratio is about 4 times, the focal length at the telephoto end in the 35 mm format is about 600 m, and the F number is about 6.3. The zoom lens is designed to be more telescopic than the conventional one, that is, to achieve a longer focal length than the conventional one and to be downsized.

JP, 2014-126850, A

By the way, in the zoom lens disclosed in Patent Document 1, high optical performance is realized by configuring the first lens group using a positive lens made of a glass material having anomalous dispersion. However, the zoom lens disclosed in Patent Document 1 is not sufficient in terms of size reduction and weight reduction of the entire zoom lens unit. In a telephoto zoom lens, the diameter of the lens forming the first lens group is large, and in the case of a positive lens, it is thick. Further, a glass material having anomalous dispersion is expensive and has a large specific gravity. Therefore, if a positive lens having anomalous dispersion is arranged in the first lens group, the cost increases and the weight becomes heavy. Further, if the first lens group becomes heavy, the drive mechanism for moving the first lens group along the optical axis at the time of zooming becomes large, and the entire zoom lens unit becomes large and heavy.

Therefore, an object of the present invention is to provide a zoom lens and an imaging device that are compact and lightweight and have high optical performance.

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 a positive refractive power and a rear group including at least one lens group Gp having a positive refractive power. The first lens group has a lens L1p1 having a positive refracting power, and the positive lens included in the first lens group has a positive refractive power. The number of lenses having a refractive power is two or less, the lens group Gp has a lens Lpn having a negative refractive power, and the following conditional expression is satisfied.
3.50 <ft/fnot/Y <9.00 (...)
63.0<νdL1p1<76.0 (2)
32.0 <νdLpn <65.0 (3)
However,
ft: focal length of the zoom lens at the telephoto end fnot: F value of the zoom lens at the telephoto end Y: maximum image height of the zoom lens νdL1p1: Abbe's number at the d line of the lens L1p1 νdLpn: d line of the lens Lpn Abbe number in

Further, in order to solve the above problems, an imaging device according to the present invention includes the zoom lens, and an imaging element that converts an optical image formed by the zoom lens on the image side of the zoom lens into an electrical signal. It is characterized by having.

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

1 is a lens cross-sectional view of a zoom lens according to a first exemplary embodiment of the present invention when focused on an object at infinity at a wide-angle end. 9A and 9B are a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the wide-angle end of the zoom lens of Example 1; FIG. 9 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when focusing on infinity in the intermediate focal length state of the zoom lens of Example 1; FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the telephoto end of the zoom lens of Example 1; FIG. 9 is a lens cross-sectional view of a zoom lens according to a second exemplary embodiment of the present invention when focused on an object at infinity at a wide-angle end. 9A and 9B are a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the wide-angle end of the zoom lens of Example 2; FIG. 9 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when focusing on infinity in the intermediate focal length state of the zoom lens of Example 2; 9A and 9B are a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the telephoto end of the zoom lens of Example 2; FIG. 8 is a lens cross-sectional view of a zoom lens according to a third exemplary embodiment of the present invention when focused on an object at infinity at a wide-angle end. 9A and 9B are a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the wide angle end of the zoom lens of Example 3; FIG. 13 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when focusing on infinity in the intermediate focal length state of the zoom lens of Example 3; FIG. 13 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the telephoto end of the zoom lens of Example 3 when focused on infinity. 16 is a lens cross-sectional view of a zoom lens according to Example 4 of the present invention when focused on an object at infinity at a wide-angle end. FIG. 14 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the wide-angle end of the zoom lens of Example 4; FIG. 16 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when focusing on infinity in the intermediate focal length state of the zoom lens of Example 4; FIG. 16 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram at the time of focusing on infinity at the telephoto end of the zoom lens of Example 4;

Embodiments of a zoom lens and an image pickup apparatus according to the present invention will be described below. However, the zoom lens and the imaging device described below are one mode of the zoom lens and the imaging device according to the present invention, and the zoom lens and the imaging device according to the present invention are not limited to the following modes.

1. Zoom lens 1-1. Optical Configuration of Zoom Lens The zoom lens according to the present embodiment includes, in order from the object side, a first lens group having a positive refractive power and a rear group. By adopting a power arrangement in which a positive refracting power is arranged on the most object side of the zoom lens, it is possible to suppress the maximum height of the axial ray, so that it is easy to downsize the zoom lens in the radial direction. become. In particular, since it is easy to reduce the size of the lens forming the first lens group in the radial direction, the volume of the lens forming the first lens group can be reduced. In a telephoto zoom lens having a long focal length, the diameter of the lens forming the first lens group is larger than the diameter of the lenses forming the other lens groups. By reducing the size of the first lens group in the radial direction, the effect of reducing the size and weight of the zoom lens as a whole becomes greater. In particular, when this power arrangement is adopted in a zoom lens configured such that the zoom pupil at the telephoto end has an entrance pupil diameter larger than 80 mm while including a focal length longer than 100 mm in 35 mm format conversion. , The effect becomes remarkable.

Furthermore, in the zoom lens, the diameter of the incident light flux for the rear group is smaller than the diameter of the incident light flux for the first lens group. Therefore, when the focus group and the image stabilization group are arranged in the rear group, the size and weight of the focus group and the image stabilization group can be reduced as compared with the case where the focus group and the image stabilization group are arranged in the first lens group. You can The optical configuration of each lens group will be described below. It should be noted that the zoom lens may substantially be composed of the first lens group and the rear group. That is, in addition to the lens group described below, an optical element having no refractive power or an extremely small refractive power may be arranged. Examples of such an optical element include various filters such as a protection filter for protecting the lens from dirt and scratches, an ND filter used for reducing the amount of incident light, and a PL filter for adjusting color. To be

(1) First Lens Group In the zoom lens, the first lens group is arranged closest to the object side. The specific lens configuration of the first lens group is not particularly limited as long as it has a positive refractive power as a whole.

Since the first lens group has a positive refracting power as a whole, the first lens group has at least one lens having a positive refracting power. That is, the lens having a positive refractive power included in the first lens group may be only this lens L1p1. However, in order to satisfactorily correct chromatic aberration and spherical aberration at the telephoto end, it is preferable that the first lens group includes a lens L1p2 having a positive refractive power, in addition to the lens L1p1. When the number of lenses having a positive refractive power included in the first lens group is increased, spherical aberration or the like is generated by adjusting the shape of each surface while arranging a strong positive refractive power in the first lens group. And a zoom lens with high optical performance can be obtained. However, the first lens group is composed of a lens having the largest diameter in the zoom lens. Therefore, when the number of lenses forming the first lens group increases, the zoom lens becomes heavy. Therefore, from the viewpoint of increasing the performance of the zoom lens and suppressing the increase in the weight of the zoom lens, in the zoom lens, the lens having a positive refractive power included in the first lens group is It shall be 2 or less.

Further, it is preferable that the first lens group has at least one lens L1n having a negative refracting power in order to correct chromatic aberration and improve image surface property.

From these things, the first lens group should be composed of a total of three lenses, one lens L1n having negative refracting power and two lenses having positive refracting power (lens L1p1 and lens L1p2). However, it is more preferable for realizing a high-performance zoom lens while suppressing an increase in cost and weight.

Further, when the first lens group includes the lens L1n having a negative refractive power, the lens L1n is preferably cemented to the lens L1p1 or the lens L1p2. By arranging the lens L1n having a negative refracting power and the lens having a positive refracting power (the lens L1p1 or the lens L1p2), as compared with a case where these lenses are arranged through an air gap, an eccentricity error Also, various manufacturing errors such as an error in the air gap between the single lenses can be reduced. Therefore, it is possible to reduce the deterioration of the optical performance due to the manufacturing error, and to reduce the variation in the performance of each product. Therefore, by cementing the lens L1n having a negative refractive power and the lens having a positive refractive power (the lens L1p1 or the lens L1p2), it is possible to manufacture a zoom lens having high optical performance with high yield.

By the way, if there is a difference in the linear expansion coefficient of the glass materials of the lenses to be cemented with each other, the shape change mode due to the expansion or contraction of the glass materials due to the change of the ambient temperature is different, and the cemented surface is stressed. The larger the diameter of the lens that makes up the cemented lens, the greater the difference in the linear expansion coefficient of the glass materials, and the greater the stress applied to this cemented surface, the more likely the cemented lens to crack or crack at the cemented surface. Occurs. When the difference in linear expansion coefficient between the lenses forming the cemented lens is large, such a phenomenon tends to occur as the diameter of the cemented lens increases. That is, since the diameter of the lens forming the first lens group is larger than that of the other lens groups, such a phenomenon is likely to occur in the cemented lens arranged in the first lens group as compared with the other lens groups. .. Therefore, the rate of change of the sample length when the temperature is changed under constant pressure (1 atm) is defined as the linear expansion coefficient, and the rate of change of the average of the sample length in the temperature range of -30°C to 70°C is defined as the average line. Assuming the expansion coefficient α, the difference between the average linear expansion coefficient α1p of the lens having a positive refractive power forming the cemented lens in the first lens group and the average linear expansion coefficient α1n of the lens L1n having a negative refractive power is It is preferably small. More specifically, it is preferable that 0<α1p−α1n<50×10 ⁻⁷ /° C. When the condition is satisfied, when the lens L1n having a negative refractive power arranged in the first lens group and the lens L1p1 or the lens L1p2 having a positive refractive power are cemented, the cemented lens of the cemented lens is changed due to a change in ambient temperature. It is preferable because cracking can be suppressed.

Further, the Abbe number of the lens L1n having a negative refractive power included in the first lens group at the d-line is smaller than 45, and at least one of the lenses having a positive refractive power included in the first lens group is included. The Abbe number of the lens (lens L1p1 or lens L1p2) at the d-line is preferably larger than 65 from the viewpoint of chromatic aberration correction. When the condition is satisfied, it is possible to realize a zoom lens in which chromatic aberration is favorably corrected even at the telephoto end.

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

Since a glass material having high anomalous dispersion has a relatively large specific gravity, when one lens having two positive refractive powers (lens L1p1, lens L1p2) is included in the first lens group, one of the lenses has anomalous dispersion. It is preferable that the other lens is made of a glass material having a high Abbe number and a small specific gravity in order to achieve high performance and light weight of the zoom lens.

(2) Rear Group The rear group is a general term for a plurality of lens groups arranged on the image side of the first lens group. The rear group includes a lens group Gp having a positive refractive power. As long as the rear group includes the lens group Gp having a positive refractive power, other lens group configurations are not particularly limited. For example, two or more lens groups having a positive refractive power may be included, or one or more lens groups having a negative refractive power may be included. If the rear lens group has a negative refracting power at the telephoto end as a whole, the refracting power arrangement has a strong telephoto tendency. Therefore, the effect of shortening the overall optical length of the zoom lens at the telephoto end as compared with the focal length becomes greater, which is preferable for downsizing the zoom lens. However, the refractive power of the entire rear lens group at the telephoto end may be negative or positive, and the sign of the refractive power of the entire rear lens group is not particularly limited. Note that a strong telephoto tendency means that the telephoto ratio (L/f, L means the optical total length, and f means the focal length) is small.

(A) Object side group Rfn and image side group Rrp
The rear group includes an object side group Rfn that includes at least one lens group on the object side of the largest air space at the wide-angle end and has a negative refracting power as a whole. It is preferable that an image side group Rrp including at least one lens group and having a positive refracting power as a whole is provided on the image side of the distance. In the rear group, an object side group Rfn having a negative refracting power as a whole is disposed closer to the object side than the largest air gap at the wide-angle end, and an image side group Rrp having a positive refracting power as a whole is disposed on the image side thereof. By adopting the refracting power arrangement of arranging, it is possible to secure a large composite lateral magnification by the object side group Rfn, which is effective in increasing the focal length of the zoom lens at the telephoto end.

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

(B) Lens group Gp
The arrangement of the lens group Gp having a positive refractive power in the rear group is not particularly limited as long as it is arranged in the rear group. For example, when the rear group is composed of the object side group Rfn having the negative refracting power and the image side group Rrp having the positive refracting power, the lens group Gp having the positive refracting power becomes the image side group Rrp. It is preferably arranged.

Further, it is preferable that the lens group Gp having the positive refractive power has at least one lens Lpn having the negative refractive power. If the lenses forming the first lens group are made of a glass material having a small specific gravity in order to reduce the weight of the first lens group, it becomes impossible to sufficiently correct chromatic aberration in the first lens group. Therefore, it is necessary to correct the chromatic aberration generated in the first lens group in the rear group. Therefore, by arranging the lens Lpn having a negative refractive power in the lens group Gp having a positive refractive power arranged in the rear group, it is possible to excellently correct the axial chromatic aberration, so that the high zoom lens of the zoom lens can be obtained. It is preferable in terms of performance improvement.

(C) Lens Group Having Negative Refractive Power The rear group preferably includes a lens group having negative refractive power. At the time of zooming, it is preferable to move the lens unit having a negative refractive power, which is arranged in the rear unit, to the image side because the focal length of the zoom lens at the telephoto end can be lengthened. However, when there are a plurality of lens groups having a negative refractive power arranged in the rear group, at least one lens group may be moved to the image side. Further, it is preferable that the lens unit having a negative refractive power to be moved to the image side is the object side unit Rfn. The lateral magnification at the telephoto end of the lens group having negative refractive power can be increased by moving the lens group having negative refractive power arranged in the rear group toward the image side. Therefore, it is possible to increase the focal length of the zoom lens at the telephoto end while keeping the zoom lens compact.

Further, it is preferable to move the lens unit having a negative refractive power, which is arranged in the rear unit, along a locus convex toward the image side in order to improve the image surface property at the intermediate focal length. When there are a plurality of lens groups having a negative refractive power arranged in the rear group, at least one lens group may be moved to the image side.

Further, among the lens groups having negative refracting power included in the rear group, the lens group having negative refracting power arranged closest to the image side is referred to as a negative lens group n. The negative lens group n is preferably a lens group different from the lens group R described below, and therefore, the negative lens group n is preferably arranged closer to the object side than the lens group R.

(D) Lens group R
Here, in the rear group, the lens group arranged closest to the image side is referred to as a lens group R. The lens group R may be the lens group Gp having the positive refractive power or the lens group having a positive refractive power other than the lens group Gp. Further, the lens group R may be a lens group having a negative refractive power.

In order to reduce the size of the zoom lens in the optical length direction at the telephoto end, it is preferable that the lens group R has a negative refractive power. By adopting a telephoto type refractive power arrangement in which a positive refractive power is arranged on the object side and a negative refractive power is arranged on the image side, the total optical length of the zoom lens at the telephoto end is shortened compared to the focal length. can do. If the lens group R has a negative refractive power, it is possible to provide this telephoto type strong refractive power arrangement, which is preferable in terms of downsizing of the zoom lens at the telephoto end.

(E) Others The zoom lens preferably has a lens unit having a negative refractive power on the object side of the lens unit R. When the lens group R has a negative refracting power, by disposing the lens group having a negative refracting power on the object side of the lens group R, it is possible to obtain a refracting power arrangement having a stronger telephoto type tendency. This is preferable in reducing the size of the zoom lens at the telephoto end.

Further, 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 a negative refractive power. By disposing the lens Lnr having a negative refractive power in the rear group, it is possible to improve the image plane property and reduce chromatic aberration.

Further, it is preferable that the rear group has at least one lens Lrp having a positive refractive power. As described later, it is more preferable that the lens Lrp is a glass material having high anomalous dispersion.

Here, in a telephoto zoom lens having a long focal length, the pupil diameter becomes large. Usually, the ND filter, the PL filter and the like are arranged on the most object side of the optical system. However, for example, in a telephoto zoom lens in which the focal length at the telephoto end in the 35 mm format exceeds 500 mm, the diameter of the first lens group becomes large, and there is no commercially available filter corresponding to such a diameter. There are cases. In the zoom lens unit, it is preferable that these filters can be inserted into the rear group. In this case, it is preferable that the filter is fixed to the image plane during zooming.

(3) Focus Group The presence or absence of the focus group in the zoom lens is not particularly limited. When focusing is performed, at least one lens in the zoom lens may be moved in the optical axis direction, and the position and refractive power of the lens are not particularly limited.

The first lens group or a part thereof may be the focus group, but it is more preferable to use any one of the lens groups forming the rear group or a part thereof as the focus group. Compared with the first lens group, the lens group forming the rear group has a small diameter, which is preferable in terms of size reduction and weight reduction of the focus group. Further, by reducing the size and weight of the focus group, it is possible to reduce the size and weight of a drive mechanism (hereinafter, referred to as a focus drive mechanism) for moving the focus group in the optical axis direction during focusing. You can Therefore, it is possible to reduce the size of the entire zoom lens unit including the lens barrel portion of the zoom lens, which is preferable. In addition to the focus drive mechanism, the zoom lens unit includes a zoom drive mechanism for relatively moving each lens group during zooming, a lens barrel that houses these, and the like.

Further, in order to suppress variation in aberration that occurs when focusing on a close object, it is preferable that the focus group be composed of a plurality of lenses.

Further, it is preferable that the focus group is composed of one single lens unit. Here, the single lens unit means a lens unit such as a single lens or a cemented lens in which a plurality of single lenses are integrated without an air gap. That is, even when the single lens unit has a plurality of optical surfaces, only the most object side surface and the most image side surface thereof are in contact with air, and the other surfaces are not in contact with air. Further, in the specification, the single lens may be either a spherical lens or an aspherical lens. In addition, the aspherical lens includes a so-called compound aspherical lens having an aspherical film attached on the surface.

When the focus group is composed of the single lens unit, the focus group does not include an air gap. Therefore, when compared with a configuration in which a plurality of single lenses are arranged in the focus group with an air gap therebetween, if the focus group is composed of one single lens unit, the size and weight of the focus group can be reduced. As a result, it is possible to further reduce the size and weight of the focus drive mechanism, and to reduce the size and weight of the zoom lens unit as a whole.

In addition, when the focus group is configured by the single lens unit described above, as compared with a configuration in which the focus group has a plurality of single lenses arranged with an air gap, the eccentricity error and the air gap between the single lenses are reduced. Various manufacturing errors such as errors can be reduced. Therefore, it is possible to reduce the deterioration of the optical performance due to the manufacturing error, and to reduce the variation in the performance of each product. Therefore, a zoom lens having high optical performance can be manufactured with high yield.

The focus group may have a positive refractive power or a negative refractive power. When the focus group has a negative refracting power, the lateral magnification of the focus group can be increased as compared with the case where the focus group has a positive refracting power, so the focus sensitivity is increased and the amount of focus movement can be reduced. This is preferable in terms of size reduction of the zoom lens. The direction of movement of the focus group at the time of focusing is not particularly limited, but when the focus group has a negative refracting power, when focusing on a close object from infinity, the focus group is moved to the image side. It is preferable to move it. In particular, the focus group is more preferably the negative lens group n described above.

The lens surface included in the focus group may be only a spherical surface or may be an aspherical surface. If the lens surface included in the focus group is only a spherical surface, the cost can be suppressed, which is preferable. On the other hand, if at least one of the lens surfaces included in the focus group is an aspherical surface, it becomes possible to configure a focus group with a small number of lenses and a small aberration variation during focusing, and the zoom lens including the focus drive mechanism can be used. It is possible to reduce the size of the entire lens unit. At this time, it is preferable that the aspherical surface has a shape that weakens the refractive power obtained from the paraxial spherical surface defined by the paraxial radius of curvature. By arranging an aspherical surface having such a shape in the focus group, it is possible to correct spherical aberration, coma aberration, and field curvature at the time of focusing, so a zoom lens with higher optical performance in the entire focusing range can be provided. Can be realized.

Further, when the focus group is provided in the rear group, it is preferable that the focus group is arranged closer to the object side than the lens group R arranged closest to the image side. On the most image side of the zoom lens, a flexible substrate or the like on which a control circuit or the like for electrically connecting the zoom lens and the image pickup apparatus main body is mounted is arranged. Therefore, when the lens group R or a part of the lens group R is used as a focus group, it is difficult to secure a space for arranging various mechanical members that configure the focus drive mechanism in the lens barrel, and the lens barrel diameter is increased. It becomes difficult to form the zoom lens in a small size due to necessity. By arranging the focus group on the object side of the lens group R, it becomes easy to secure a space for arranging various mechanical members constituting the focus drive mechanism, and the diameter of the lens barrel of the zoom lens can be reduced. It is possible to reduce the size of the zoom lens unit as a whole.

When the focus group is provided in the rear group, it is preferable that the focus group is arranged on the image side of the lens group having a positive refractive power. By arranging the focus group on the image side of the lens group having a positive refractive power, the light flux converged by the lens group having a positive refractive power can be made incident on the focus group. Can be promoted. Further, since it is possible to reduce the weight of the focus by reducing the diameter of the focus group, it is possible to reduce the size of the zoom lens unit as a whole, which is preferable.

In the zoom lens, the plurality of lens groups or a part of the plurality of lens groups may be used as the focus group. That is, you may focus by a floating system. By adopting the floating system, it is possible to improve the spherical aberration and the image plane property at the time of near-focusing, which is preferable in terms of high performance.

(4) Aperture Stop In the zoom lens, the arrangement of the aperture stop is not particularly limited, but it is preferable to arrange the aperture stop in the rear group in order to downsize the aperture unit. However, the aperture stop mentioned here is a stop that defines the axial light flux diameter of the zoom lens, that is, a stop that defines the F value of the zoom lens.

The diaphragm unit includes an aperture diaphragm, a mechanical member for controlling the operation of the aperture diaphragm, a control board, and the like. In the zoom lens, the light flux converged by the first lens group having a positive refractive power enters the rear group. Therefore, the diameter of the incident light flux for the rear group is smaller than the diameter of the incident light flux for the first lens group. Therefore, the aperture diameter can be reduced by disposing the aperture stop in the rear group. Further, in the rear group, if the aperture stop is arranged on the image side of the lens group Gp having a positive refractive power, the incident light flux can be further converged by the lens group Gp, so that the diameter of the aperture stop can be reduced and the aperture stop can be reduced. It is more preferable for downsizing the unit.

Furthermore, when the lens group R disposed closest to the image side in the rear group is fixed to the image plane during zooming, an aperture stop may be provided on the object side of the lens group R or inside the lens group R. preferable. When the lens group R is fixed to the image plane during zooming, the magnification of the lens group R does not change, so there is no need to change the aperture diameter of the aperture stop during zooming. Therefore, the F value of the zoom lens can be kept constant during zooming.

(5) Anti-Vibration Group In the zoom lens, the presence or absence of the anti-vibration group is not particularly limited. For example, at least one of the plurality of lenses forming the zoom lens is decentered by moving it in a direction substantially orthogonal to the optical axis to correct image blur caused by camera shake or the like. You may do it.

When such an image stabilizing group is provided in the zoom lens, the arrangement of the image stabilizing group is not particularly limited, but providing the image stabilizing group in the rear group helps reduce the diameter of the image stabilizing group. Is preferred. The diameter of the incident light flux for the rear group is smaller than the diameter of the incident light flux for the front group. Therefore, by arranging the image stabilizing group in the rear group, the size and weight of the image stabilizing group can be reduced as compared with the case where the image stabilizing group is arranged in the front group.

Further, it is preferable that the image stabilizing unit is arranged closer to the image side than the aperture stop. On the image side of the aperture stop, the fluctuation of the ray height during zooming is small, so that the fluctuation of aberrations during zooming is also small. Therefore, it is possible to reduce aberration fluctuations during image stabilization, and it is possible to maintain high optical performance even during image stabilization. Further, by disposing the image stabilizing group on the image side of the aperture stop, it is possible to reduce the movement amount of the image stabilizing group when correcting the image blur by the image stabilizing group. Therefore, the vibration proof unit can be downsized, and the zoom lens unit as a whole can be downsized.

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

The number of lenses forming the image stabilizing group is not particularly limited. It is preferable to configure the image stabilizing unit with a plurality of lenses in order to suppress aberration fluctuation during image stabilizing. At this time, it is preferable that the image stabilizing unit has at least one lens having a negative refractive power and at least one lens having a positive refractive power. By having at least one lens having a negative refracting power and at least one lens having a positive refracting power in the image stabilization group, it is possible to suppress the occurrence of chromatic aberration during image stabilization and to realize a zoom lens with higher optical performance. be able to.

It is more preferable that the image stabilizing unit is composed of one lens having a negative refractive power and one lens having a positive refractive power. By configuring the image stabilizing group with only two lenses, it is possible to reduce the size and weight of the image stabilizing group, reduce the size of the image stabilizing unit, and reduce the overall size of the zoom lens unit. Can be planned.

When the image stabilizing unit is composed of one lens having a negative refractive power and one lens having a positive refractive power, it is preferable that these two lenses are cemented. That is, it is preferable that the image stabilizing unit is composed of a single lens unit in which a lens having a negative refractive power and a lens having a positive refractive power are cemented. By constructing the image stabilizing unit from one single lens unit, it is possible to achieve miniaturization as compared with a configuration in which a lens having a negative refractive power and a lens having a positive refractive power are arranged with an air gap therebetween. In addition, it is possible to reduce various manufacturing errors such as an eccentricity error and an error in air distance between single lenses. Therefore, it is possible to reduce the deterioration of the optical performance due to the manufacturing error, and to reduce the variation in the performance of each product. Therefore, a zoom lens having high optical performance can be manufactured with high yield.

Further, when the image stabilizing group is provided in the zoom lens, the lens surface included in the image stabilizing group may be only a spherical surface or may include an aspherical surface. If all the lens surfaces included in the image stabilizing group are spherical surfaces, it is preferable for cost reduction.

On the other hand, if at least one of the lens surfaces included in the image stabilization group is an aspherical surface, it is easy to satisfy the optical performance required for the zoom lens even when the image stabilization group is configured with a small number of lenses. become. Therefore, since it is possible to configure the number of lenses of the image stabilizing group to be small, the size and weight of the image stabilizing group can be reduced. At this time, it is preferable that the aspherical surface has a shape that weakens the refractive power obtained from the paraxial spherical surface defined by the paraxial radius of curvature. By disposing the aspherical surface having such a shape in the image stabilizing group, it is possible to correct coma aberration and one-sided blur at the time of decentering, so that it is possible to realize a zoom lens having higher optical performance.

It is preferable that the image stabilizing unit is a lens unit fixed in the optical axis direction with respect to the image plane during zooming or a part thereof. In order to move the image stabilization group in the direction orthogonal to the optical axis during image stabilization, a mechanical board for driving the image stabilization group and a flexible board on which an electronic circuit for controlling the mechanical member is mounted are provided. .. When the image stabilizing unit moves in the optical axis direction during zooming, it is difficult to secure a space for accommodating the flexible substrate and the like, and it is difficult to reduce the size of the zoom lens unit as a whole. In addition, when the flexible substrate is flexibly arranged in the lens barrel, the anti-vibration group may be eccentric due to the reaction force from the flexible substrate, which may deteriorate the optical performance of the zoom lens, which is not preferable.

In the rear group, when the lens group R arranged closest to the image side has a negative refracting power, it is preferable that the lens group R or a part thereof be a vibration reduction group. As described above, when the lens group R has a negative refracting power, the zoom lens has a telephoto-type refracting power arrangement with a strong tendency, and the diameter of the lens group R can be reduced. Therefore, by disposing the image stabilization group in the lens group R, the size and weight of the image stabilization group can be reduced, and the size reduction of the image stabilization unit becomes easier.

When a part of the lens group R is the image stabilizing group, it is preferable that at least one lens is arranged on the image side of the image stabilizing lens group. Further, it is preferable that the combined focal length of all the lenses arranged on the image side of the image stabilizing group is negative. By arranging the negative refractive power on the image side of the image stabilization group, it is possible to increase the shake correction coefficient of the image stabilization group, that is, the amount of movement of the image plane per unit amount of movement of the image stabilization group. It is possible to reduce the movement amount of the image stabilizing unit in the above, and it becomes easier to downsize the image stabilizing unit.

(6) Lens Group Configuration The number of lens groups constituting the zoom lens is not particularly limited, but for example, a first lens group having a positive refractive power, a second lens group having a negative refractive power, Third lens group having negative refractive power, fourth lens group having positive refractive power, fifth lens group having positive refractive power, sixth lens group having negative refractive power, and negative refractive power A zoom lens having a seventh lens group including a seventh lens group and a rear lens group including the second lens group and thereafter, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. And a fourth lens group having a positive refracting power, a fifth lens group having a negative refracting power, and a sixth lens group having a negative refracting power. Various lens group configurations such as a zoom lens having a six-group configuration can be adopted. The specific lens group configuration of the zoom lens is not particularly limited as long as the configuration includes the first lens group having positive refractive power in order from the object side and the rear group.

1-2. Operation during zooming In the zoom lens, when zooming from the wide-angle end to the telephoto end, the air space between adjacent lens groups is changed. Further, it is preferable to change the air distance between the lens groups so that the distance between the first lens group and the rear group increases during zooming from the wide-angle end to the telephoto end.

The rear group includes at least one lens group Gp having a positive refractive power, and may include other lens groups. When the rear group includes a plurality of lens groups, the air space between the adjacent lens groups in the rear group also changes. When zooming from the wide-angle end to the telephoto end, it suffices that the air spacing between adjacent lens groups be changed, and the increase or decrease of the air spacing between the lens groups is not particularly limited. It is preferable that the air distance between the first lens group and the lens group that is arranged closest to the object side in the rear group be increased in order to obtain a high zoom ratio, but the air distance between the other lens groups is not increased or decreased. It is not particularly limited. Further, when changing the magnification, all the lens groups constituting the zoom lens may be moved in the optical axis direction, or some lens groups may be fixed in the optical axis direction and the remaining lens groups may be moved in the optical axis direction. However, the presence or absence of movement of each lens group and the direction of movement are not particularly limited.

In the case of a large zoom lens having a long focal length such that the entrance pupil diameter exceeds 80 mm, the weight of the first lens group exceeds several hundred grams. In order to move the lens group having such a weight to a predetermined position with high accuracy during zooming, a large load is applied to a mechanical member for driving the first lens group, and the zoom lens operates during zooming. The mechanical structure for controlling the vehicle is also enlarged. Therefore, at the time of zooming, it is possible to reduce the size and weight of the zoom lens unit as a whole by fixing the first lens group arranged closest to the object side in the zoom lens in the optical axis direction with respect to the image plane. It is preferable for the purpose. Further, if the first lens group is fixed to the image plane, the movement of the center of gravity is reduced, so that it is easy to suppress image blurring during image pickup.

Further, by fixing the first lens group in the optical axis direction with respect to the image plane during zooming, the lens barrel length does not change, so that it is easy to make at least the object side of the lens barrel a watertight structure. This is preferable because it is easy to prevent dust and water from entering the lens barrel from the object side of the lens barrel.

Further, the lens group R, which is disposed closest to the image side in the rear group, can be fixed in the optical axis direction with respect to the image plane during zooming, so that the image side of the lens barrel also has a watertight structure. This is preferable because it facilitates and prevents dust and water from entering the lens barrel from the image side of the lens barrel. In addition, as described above, the lens group R can be a fixed group to reduce the diameter of the lens barrel.

1-3. Conditional Expression In the zoom lens, it is preferable to adopt the above-described configuration and satisfy one or more conditional expressions described below.

1-3-1. Conditional expression (1)
3.50 <ft/fnot/Y <9.00 (...)
However,
ft: focal length of the zoom lens at the telephoto end fnot: F value of the zoom lens at the telephoto end Y: maximum image height of the zoom lens

The conditional expression (1) is an expression that defines the size of the entrance pupil diameter. By satisfying conditional expression (1), the entrance pupil diameter becomes an appropriate size. Therefore, it is possible to reduce the weight of the zoom lens while suppressing the increase in the diameter of the first lens group while achieving the telephoto distance of the zoom lens.

On the other hand, when the numerical value of the conditional expression (1) is equal to or more than the upper limit value, the entrance pupil diameter becomes too large. The diameter of the lenses forming the first lens group is larger than the entrance pupil diameter. Therefore, it becomes difficult to reduce the weight of the first lens group, which is not preferable. On the other hand, if the numerical value of the conditional expression (1) is less than or equal to the lower limit value, it becomes difficult to achieve the telephoto of the zoom lens, which is not preferable.

In order to obtain the above effect, the lower limit value of conditional expression (1) is more preferably 3.90, further preferably 4.20, further preferably 4.50, and 4.70. It is even more preferred to be present. The upper limit value of conditional expression (1) is more preferably 8.00, further preferably 7.50, further preferably 7.00, and further preferably 6.50. ..

1-3-2. Conditional expression (2)
63.0<νdL1p1<76.0 (2)
However,
νdL1p1: Abbe number at d line of lens L1p1

The conditional expression (2) is an expression that defines the Abbe number at the d-line of the lens L1p1 having a positive refractive power included in the first lens group. By satisfying the conditional expression (2), it is possible to satisfactorily correct the chromatic aberration, and it is possible to realize a zoom lens having high optical performance and to reduce the weight of the zoom lens.

On the other hand, when the numerical value of the conditional expression (2) is equal to or larger than the upper limit value, the Abbe number of the lens L1p1 at the d-line becomes large. Glass materials with a large Abbe number tend to have a large specific gravity. The first lens group is composed of lenses having a larger diameter than the other lens groups. For the same diameter, a lens having a positive refractive power is heavier by a thickness than a lens having a negative refractive power. Therefore, if the numerical value of the conditional expression (2) is equal to or more than the upper limit value, it becomes difficult to reduce the weight of the first lens group, which is not preferable. On the other hand, if the numerical value of the conditional expression (2) is less than or equal to the lower limit value, it becomes difficult to correct chromatic aberration at the telephoto end, and it becomes difficult to realize a zoom lens having high optical performance, which is not preferable.

In order to obtain the above effects, the lower limit value of conditional expression (2) is more preferably 64.0, further preferably 66.0, and further preferably 68.0. The upper limit of conditional expression (2) is more preferably 74.0, even more preferably 72.0, and even more preferably 71.0.

1-3-3. Conditional expression (3)
32.0 <νdLpn <65.0 (3)
However,
νdLpn: Abbe number at d line of lens Lpn

The conditional expression (3) is an expression that defines the Abbe number at the d-line of the lens Lpn having a negative refractive power included in the lens group Gp. If the lenses constituting the first lens group are made of a glass material having a low specific gravity in order to reduce the weight of the first lens group, the chromatic aberration generated in the first lens group will be undercorrected. Therefore, it is necessary to correct chromatic aberration in the rear group that could not be sufficiently corrected in the first lens group. In order to reduce the weight of the first lens group, it is effective that the lens having a positive refractive power included in the first lens group is made of a glass material having a low specific gravity. In this case, in the rear group, the lens Lpn having a negative refractive power arranged in the lens group Gp having a positive refractive power is made of a glass material that satisfies the above conditional expression (3), whereby axial chromatic aberration is increased. Can be satisfactorily corrected, and a zoom lens having high optical performance and reduced weight can be realized.

On the other hand, when the numerical value of the conditional expression (3) is equal to or more than the upper limit value, the Abbe number of the lens Lpn at the d-line becomes large. In that case, correction of axial chromatic aberration becomes insufficient. On the other hand, when the numerical value of the conditional expression (3) becomes less than or equal to the lower limit value, the Abbe number at the d-line of the lens Lpn becomes small. In that case, correction of chromatic aberration at the telephoto end becomes excessive. Therefore, in any case, it is difficult to realize a zoom lens having high optical performance, which is not preferable.

In order to obtain the above effects, the lower limit value of conditional expression (3) is more preferably 33.0, further preferably 35.0, further preferably 37.0, and 38.0. It is even more preferred to be present. Further, the upper limit of conditional expression (3) is more preferably 62.0, further preferably 59.0, further preferably 56.0, further preferably 55.0. , 54.0 is even more preferable.

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

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

On the other hand, when the numerical value of the conditional expression (4) is less than or equal to the lower limit value, the refractive power of the first lens group becomes too large, so spherical aberration and field curvature at the telephoto end become large, and in order to correct this. Since it is necessary to increase the number of lenses for aberration correction, it is difficult to realize a compact and lightweight zoom lens having high optical performance, which is not preferable. If the numerical value of the conditional expression (4) is equal to or more than the upper limit value, the refractive power of the first lens group becomes too small. Therefore, it is difficult to shorten the optical total length of the zoom lens at the telephoto end, and it is difficult to reduce the size of the zoom lens, which is not preferable.

In order to obtain the above effect, the lower limit of conditional expression (4) is more preferably 0.26, further preferably 0.27, further preferably 0.28, and 0.29. It is even more preferable to be present, and it is even more preferable to be 0.30. Further, the upper limit value of conditional expression (4) is more preferably 0.60, further preferably 0.56, further preferably 0.52, still more preferably 0.48. , 0.45 is even more preferable.

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

Conditional expression (5) is an expression for defining the lateral magnification of the lens unit R disposed closest to the image side in the rear group. By satisfying the conditional expression (5), it is possible to provide a refractive power arrangement having a strong telephoto tendency, and it is possible to shorten the optical total length of the zoom lens at the telephoto end as compared with the focal length. It is easy to reduce the size.

On the other hand, if the numerical value of the conditional expression (5) becomes less than or equal to the lower limit value, the lateral magnification of the lens unit R becomes small and the telephoto tendency is weakened. Therefore, the total optical length at the telephoto end should be shorter than the focal length. It becomes difficult to reduce the size of the zoom lens, which is not preferable. On the other hand, when the numerical value of the conditional expression (5) is equal to or larger than the upper limit value, the lateral magnification of the lens unit R becomes large and the effect of magnifying various aberrations becomes large. Therefore, it becomes difficult to correct aberrations at the telephoto end, and it is necessary to increase the number of lenses for aberration correction in order to realize a zoom lens having high optical performance. Therefore, it is difficult to realize a compact and lightweight zoom lens having high optical performance, which is not preferable.

In obtaining the above effect, the lower limit value of conditional expression (5) is more preferably 1.25, further preferably 1.30, further preferably 1.35, and 1.40. It is even more preferably, and even more preferably 1.45. The upper limit value of conditional expression (5) is more preferably 2.45, further preferably 2.40, further preferably 2.35, and further preferably 2.30. It is even more preferably 2.20.

1-3-6. Conditional expression (6)
2.50 <βnRT <6.00 (6)
However,
βnRT: Composite lateral magnification from the negative lens group n to the lens group R at the telephoto end

Conditional expression (6) is an expression for defining the combined lateral magnification at the telephoto end of the lens located on the image side from the negative lens group n. As described above, the negative lens group n is the lens group having the negative refracting power which is disposed closest to the image side among the lens groups having the negative refracting power included in the rear group. By satisfying the conditional expression (6), a refractive power arrangement having a stronger telephoto tendency can be obtained, and the total optical length at the telephoto end can be made shorter than the focal length, and the zoom lens can be easily downsized. become.

On the other hand, when the numerical value of the conditional expression (6) is less than or equal to the lower limit value, the combined lateral magnification at the telephoto end due to the lens groups arranged after the negative lens group n becomes small and the telephoto tendency weakens, so that at the telephoto end. It becomes difficult to shorten the total optical length as compared with the focal length, and it becomes difficult to reduce the size of the zoom lens, which is not preferable. When the numerical value of the conditional expression (6) is equal to or more than the upper limit value, the combined lateral magnification at the telephoto end by the lens groups arranged after the negative lens group n becomes large and the magnifying action of various aberrations becomes large. Therefore, it becomes difficult to correct aberrations at the telephoto end, and it is necessary to increase the number of lenses for aberration correction in order to realize a zoom lens having high optical performance. Therefore, it is difficult to realize a compact and lightweight zoom lens having high optical performance, which is not preferable.

In order to obtain the above effects, the lower limit value of conditional expression (6) is more preferably 2.55, further preferably 2.60, further preferably 2.65, and 2.70. It is even more preferable that it is present, and it is even more preferable that it is 2.75. The upper limit of conditional expression (5) is more preferably 5.80, further preferably 5.50, further preferably 5.20, and further preferably 5.00. Even more preferably, it is 4.70.

1-3-7. Conditional expression (7)
1.79 <NdL1n <1.92 (7)
However,
NdL1n: Refractive index of lens L1n at d line

Conditional expression (7) is an expression for defining the refractive index at the d-line of the lens L1n having a negative refractive power included in the first lens group. In the lens group having a positive refractive power, the lens having a negative refractive power is made of a glass material having a high refractive index, and the lens having a positive refractive power is made of a glass material having a low refractive index, thereby obtaining the Petzval sum. It is common to make a correction. However, since the high-refractive index glass material is expensive, if the refractive index of the lens L1n is too high, it becomes difficult to configure the zoom lens at low cost. Further, since the glass material having a high refractive index has a large specific gravity, it is not preferable in terms of reducing the weight of the zoom lens. By satisfying conditional expression (7), cost reduction and weight reduction of the zoom lens can be achieved while ensuring good image plane property.

On the other hand, when the numerical value of the conditional expression (7) is less than or equal to the lower limit value, the refractive index of the lens L1n becomes small, and it becomes difficult to correct the image surface property, which is not preferable. Further, when the numerical value of the conditional expression (7) is not less than the upper limit value, the refractive index of the lens L1n becomes large. A glass material having a high refractive index is expensive and tends to have a large specific gravity. Therefore, if the numerical value of the conditional expression (7) is equal to or more than the upper limit value, it is not preferable in terms of cost reduction and weight reduction of the zoom lens.

When the first lens group includes a plurality of lenses L1n having negative refractive power, one of the lenses may satisfy the conditional expression (7). Although any lens may satisfy the conditional expression (7) as long as it is a lens L1n having a negative refractive power included in the first lens group, in order to correct lateral chromatic aberration better, in the first lens group, It is preferable that the lens L1n arranged closest to the object side satisfies the conditional expression (7).

In order to obtain the above effect, the lower limit of conditional expression (7) is more preferably 1.80. Further, the upper limit of conditional expression (7) is more preferably 1.91.

1-3-8. Conditional expression (8)
0.010 <ΔPgFLrp <0.070 (8)
However,
ΔPgFLrp: Anomalous dispersion of the lens having the largest anomalous dispersion among the lenses Lrp having a positive refractive power included in the rear group, where anomalous dispersion is C7 (partial dispersion ratio: 0.5393, νd: 60.49) and F2 (partial dispersion ratio: 0.5829, νd: 36.30) and the deviation of the partial dispersion ratio from the reference line when the straight line passing through the coordinates of νd is used as the reference line. Is that

Conditional expression (8) is an expression for defining the anomalous dispersion of the lens Lrp when the rear group includes at least one lens Lrp having a positive refractive power. In general, chromatic aberration is corrected by using a lens having a negative refractive power made of a high-dispersion glass material and a lens having a positive refractive power made of a low-dispersion glass material. However, in the high-dispersion glass material, the refractive index changes from a short wavelength to a long wavelength in the visible wide range in a positive quadratic curve, whereas in the low-dispersion glass material, the refractive index changes linearly. Even if two lenses are combined, it is difficult to correct chromatic aberration in all wavelength ranges without excess or deficiency. On the other hand, a lens made of a glass material having a positive anomalous dispersion has a positive quadratic curve in its refractive index from a short wavelength to a long wavelength, like a high dispersion glass material. Therefore, if a lens having a positive refractive power is made of a glass material having a positive anomalous dispersion property, it becomes easy to correct chromatic aberration in the long wavelength region without excess or deficiency. Therefore, by satisfying conditional expression (8), chromatic aberration from the wide-angle end to the telephoto end of the zoom lens can be better corrected, and a zoom lens having high optical performance over the entire zoom range is realized. It will be easier.

On the other hand, if the numerical value of the conditional expression (8) is less than or equal to the lower limit value, the anomalous dispersion of the lens Lrp becomes small, and it becomes difficult to correct chromatic aberration in the entire visible wide range without excess or deficiency, which is not preferable. When the value of the conditional expression (8) is equal to or more than the upper limit value, the anomalous dispersion of the lens Lrp becomes large, which is preferable for correcting chromatic aberration. However, a glass material having a high anomalous dispersion is generally expensive, so that the zoom lens It is not preferable for cost reduction.

In order to obtain the above effect, the lower limit value of conditional expression (8) is more preferably 0.015, further preferably 0.019, further preferably 0.022, and 0.025. It is even more preferable to be present, and it is even more preferable to be 0.027. Further, the upper limit value of conditional expression (8) is more preferably 0.065, further preferably 0.060.

The rear group may have at least one lens Lrp having a positive refractive power. When the number of lenses Lrp included in the rear group is one, it is preferable that the lenses Lrp satisfy the conditional expression (8). When the rear group includes a plurality of lenses Lrp, the lens having the largest anomalous dispersion may satisfy the conditional expression (8). Further, the rear group may include a plurality of lenses that satisfy the conditional expression (8). If a plurality of lenses having a positive refractive power satisfying conditional expression (8) are present in the rear group, chromatic aberration can be corrected better, and a zoom lens having high optical performance can be realized more easily. You can
When the anomalous dispersion of the lens having the largest anomalous dispersion among the lenses having negative refractive power included in the rear group is defined in the same manner as above, the condition similar to the conditional expression (8) is satisfied. It is also preferable to

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 of the zoom lens at the wide-angle end

Conditional expression (9) is an expression for defining the ratio of the focal length of the first lens group to 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, the zoom lens can be easily downsized at the wide-angle end, and the optical performance can be improved. It is possible to realize a high zoom lens.

On the other hand, when the numerical value of the conditional expression (9) is less than or equal to the lower limit value, the refractive power of the first lens group becomes too large, so that the amount of field curvature generated at the wide-angle end becomes large. Therefore, the optical performance at the wide-angle end deteriorates, which is not preferable. When the numerical value of the conditional expression (9) is equal to or more than the upper limit value, the refractive power of the first lens group becomes too small. Therefore, the total optical length at the wide-angle end becomes long, which is not preferable in terms of downsizing.

In order to obtain the above effect, the lower limit value of conditional expression (9) is more preferably 0.84, further preferably 0.88, further preferably 0.92, and 0.96. It is even more preferable to be present, and it is even more preferable to be 1.00. The upper limit value of conditional expression (9) is more preferably 2.80, further preferably 2.60, further preferably 2.40, and further preferably 2.10. Even more preferably, it is 1.80.

1-3-10. Conditional expression (10)
1.83 <NdLnr <2.20 (10)
However,
NdLnr: Refractive index of lens Lnr at d line

Conditional expression (10) is an expression for defining the refractive index at the d-line of the lens Lnr having a negative refractive power included in the rear group. As described above, it is common to correct Petzval sum by making the lens having a negative refractive power a glass material having a high refractive index and the lens having a positive refractive power a glass material having a low refractive index. Is. However, since the high refractive index glass material is expensive, if the refractive index of the lens Lnr is too high, it becomes difficult to configure the zoom lens at low cost. Further, since the glass material having a high refractive index has a large specific gravity, it is not preferable in terms of reducing the weight of the zoom lens. By satisfying the conditional expression (10), good image surface property can be secured, and cost reduction and weight reduction of the zoom lens can be achieved.

On the other hand, when the numerical value of the conditional expression (10) is less than or equal to the lower limit value, the refractive index of the lens Lnr becomes small, which makes it difficult to correct the image surface property, which is not preferable. Further, when the numerical value of the conditional expression (10) is equal to or more than the upper limit value, the refractive index of the lens Lnr increases. A glass material having a high refractive index is expensive and tends to have a large specific gravity. Therefore, if the numerical value of the conditional expression (10) is equal to or more than the upper limit value, it is not preferable in terms of cost reduction and weight reduction of the zoom lens.

In the case where the rear group includes a plurality of lenses Lnr having negative refractive power, one of the lenses may satisfy the conditional expression (10), and any lens Lnr having negative refractive power included in the rear group May satisfy the conditional expression (10).

In order to obtain the above effect, the lower limit value of the conditional expression (10) is more preferably 1.86, further preferably 1.88, and further preferably 1.89. Further, the upper limit value of conditional expression (10) is more preferably 2.10, further preferably 2.06, further preferably 2.01 and further preferably 1.96. Even more preferably, it is 1.92.

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

1-3-11. Conditional expression (11)
0.80<BFw/(fw×tanωw)<4.50 (11)
However,
BFw: Air equivalent length at the wide-angle end from the lens surface closest to the image side to the image plane of the zoom lens fw: Focal length of the zoom lens at the wide-angle end ωw: Outmost axis of the zoom lens at infinity at the wide-angle end Half-angle of chief ray

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

On the other hand, if the numerical value of the conditional expression (11) is less than or equal to the lower limit value, that is, if the back focus becomes too short for the maximum image height, it is difficult to secure the back focus suitable for the interchangeable lens at the wide-angle end. Is not preferable. If the numerical value of the conditional expression (11) is equal to or more than the upper limit value, that is, the back focus becomes long with respect to the maximum image height, it becomes difficult to reduce the size of the zoom lens at the wide angle end, which is not preferable.

In order to obtain the above effect, the lower limit value of conditional expression (11) is more preferably 0.90, further preferably 1.50, and further preferably 1.80. The upper limit value of conditional expression (11) is more preferably 4.00, further preferably 3.50, further preferably 3.20, and further preferably 2.90. It is even more preferably 2.80.

1-3-12. Conditional expression (12)
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

The conditional expression (12) is an expression for defining the ratio between the optical total length at the telephoto end of the zoom lens and the focal length of the zoom lens at the telephoto end. By satisfying the conditional expression (12), the ratio between the optical total length of the zoom lens at the telephoto end and the focal length of the zoom lens at the telephoto end becomes good, and the optical total length is shorter than the focal length, which is small and lightweight. It is possible to realize a zoom lens with high optical performance.

On the other hand, if the numerical value of the conditional expression (12) is less than or equal to the lower limit value, that is, if the total optical length at the telephoto end becomes too short compared to the focal length, it is difficult to satisfactorily correct various aberrations at the telephoto end. And the optical performance deteriorates. Further, the error sensitivity is increased, the optical performance is largely deteriorated due to the manufacturing error, and the variation in the performance of each product is increased. On the other hand, when the numerical value of the conditional expression (12) is equal to or larger than the upper limit value, that is, when the total optical length at the telephoto end becomes longer than the focal length, the amount of movement of each lens unit during zooming is required to obtain a predetermined zoom ratio. Is increased, which leads to an increase in the size of a variable-magnification drive mechanism for moving each lens group along the optical axis, making it difficult to reduce the weight of the zoom lens unit.

In order to obtain the above effect, the lower limit value of conditional expression (12) is more preferably 0.42, further preferably 0.45, further preferably 0.48, and 0.51. It is even more preferred to be present. Further, the upper limit value of conditional expression (12) is more preferably 0.72, further preferably 0.70, further preferably 0.68, and further preferably 0.66. , 0.64 is even more preferable.

2. Imaging Device Next, an imaging device according to the present invention will be described. An image pickup apparatus according to the present invention includes the zoom lens according to the present invention, and an image pickup element that is provided on the image plane side of the zoom lens and that converts an optical image formed by the zoom lens into an electrical signal. It is characterized by

Here, the image pickup device or the like is not particularly limited, and a solid-state image pickup device such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The image pickup apparatus according to the present invention is suitable for an image pickup apparatus using these solid-state image pickup elements such as a digital camera and a video camera. Further, the image pickup device may be a lens fixed type image pickup device in which a lens is fixed to a housing, or may be a lens interchangeable type image pickup device such as a single-lens reflex camera or a mirrorless single-lens camera. Of course. Particularly, the zoom lens according to the present invention can secure a back focus suitable for the interchangeable lens system. Therefore, it is suitable for an image pickup apparatus such as an optical viewfinder, a phase difference sensor, and a single-lens reflex camera having a reflex mirror for branching light to these.

The imaging device electrically processes captured image data acquired by an image sensor to change the shape of the captured image, and image correction data used to process the captured image data in the image processing unit. It is more preferable to have an image correction data holding unit that holds an image correction program and the like. When the size of the zoom lens is reduced, distortion (distortion) of the shape of the captured image formed on the image plane is likely to occur. At that time, the image correction data holding unit holds the distortion correction data for correcting the distortion of the captured image shape in advance, and the image processing unit uses the distortion correction data held in the image correction data holding unit. It is preferable to correct the distortion of the captured image shape. According to such an imaging device, it is possible to further reduce the size of the zoom lens, obtain an excellent captured image, and reduce the size of the entire imaging device.

Further, in the image pickup apparatus according to the present invention, the magnification chromatic aberration correction data is held in advance in the image correction data holding unit, and the magnification chromatic aberration correction data held in the image correction data holding unit is used in the image processing unit. It is preferable to correct lateral chromatic aberration of the captured image. By correcting the chromatic aberration of magnification, that is, the chromatic distortion aberration by the image processing unit, it becomes possible to reduce the number of lenses forming the optical system. Therefore, according to such an image pickup apparatus, it is possible to further reduce the size of the zoom lens, obtain an excellent captured image, and reduce the size of the entire image pickup apparatus.

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

(1) Optical Configuration of Zoom Lens FIG. 1 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 1 according to the present invention at the wide angle end when focused on an object at infinity. The zoom lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, and a positive lens group G3. A fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, a sixth lens group G6 having a negative refractive power, and a seventh lens group G7 having a negative refractive power. It consists of The aperture stop S is arranged on the object side of the seventh lens group G7. In this embodiment, the rear group includes 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. It is configured. The lens group Gp having a positive refractive power is the fourth lens group G4. The rear group includes 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.

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

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

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, and a biconcave lens L8.

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 in which a biconvex lens L11 and a biconcave lens L12 are cemented. The biconcave lens L12 is the lens Lpn according to the present invention and also the lens Lnr. The biconvex lens L9, the biconvex lens L10, and the biconvex lens L11 are lenses Lrp according to the present invention, and ΔPgFLrp is 0.0375.

The fifth lens group G5 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape on the object side and a biconvex lens L14 are cemented. The negative meniscus lens L13 having a convex shape on the object side is the lens Lnr according to the present invention.

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

The seventh lens group G7 has, in order from the object side, an aperture stop S, a cemented lens in which a negative meniscus lens L17 having a convex shape on the object side and a biconvex lens L18 are cemented, and a convex lens L19 and a biconcave lens L20 are cemented. A cemented lens, a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented, a lens L23 which is a parallel flat plate having no substantial refracting power, and a biconvex lens L24 and a biconcave lens L25 are cemented It is composed of a lens. The lens L23 is a filter such as an ND filter or a PL filter. The filter is configured such that the filter can be inserted into the zoom lens unit, and the filter is inserted from the outside of the lens barrel. The filter has any configuration in the zoom lens according to the present invention. Further, hereinafter, a filter similar to the filter in other embodiments will be referred to as an insertion filter.

In the zoom lens of Embodiment 1, upon zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction with respect to the image plane, and 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 toward the image side so as to draw a convex locus, the fifth lens group G5 is fixed in the optical axis direction, and the sixth lens group G6 The seventh lens group G7 is fixed in the optical axis direction by moving so as to draw a convex locus on the image side.

Here, among the lens groups included in the rear group, a lens group having a negative refractive power is drawn with respect to the object-side lens group, when the magnification is changed from the wide-angle end to the telephoto end, a convex locus is drawn on the image side. Such movement improves the image plane property at the intermediate focal length. In this embodiment, the sixth lens group G6 is moved with respect to the fifth lens group G5 so as to draw a convex locus on the image side at the time of zooming from the wide-angle end to the telephoto end, thereby achieving good intermediate focal length. Secures good image quality. In the present embodiment, the sixth lens group is a focus group, and the sixth lens group G6 moves to the image side along the optical axis when focusing on an object at infinity to a near object.

Further, when a camera shake or the like occurs, it is preferable to correct image blur by decentering at least one lens included in the zoom lens. In this embodiment, for example, a cemented lens in which the convex lens L19 and the biconcave lens L20 included in the seventh lens group G7 are cemented is a vibration reduction group, and the vibration reduction group is moved in a direction perpendicular to the optical axis to cause camera shake or the like. It is preferable to shift the image when it occurs to correct the image blur.

Further, “IMG” shown in FIG. 1 is an image forming surface, and specifically represents an image capturing surface of a solid-state image sensor such as a CCD sensor or a CMOS sensor, or a film surface of a silver salt film. Further, a parallel plate having no substantial refracting power such as a cover glass CG is provided on the object side of the image plane IMG. Since these points are the same in each lens cross-sectional view shown in other examples, description thereof will be omitted below.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 1 shows surface data of the zoom lens. In Table 1, “surface number” is the order of the lens surfaces counted from the object side, “r” is the radius of curvature of the lens surface, “d” is the interval on the optical axis of the lens surface, and “Nd” is the d line (wavelength). λ=587.6 nm), “vd” is the Abbe number for the d-line, and “H” is the effective radius. Further, "S" displayed in the next column of the surface number represents an aperture stop. Further, "D6", "D16", etc. in the column of the interval on the optical axis of the lens surface are variable intervals at which the interval on the optical axis of the lens surface changes during zooming or focusing. Means that. In the tables, all units of length are "mm" and all units of angle of view are "°". The radius of curvature "0.0000" means a plane. In addition, the 46th surface and the 47th surface in Table 1 are surface data of the insertion filter, and the 52nd surface and the 53rd surface are surface data of the cover glass CG.

Table 2 is a specification table of the zoom lens. The specification table shows the focal length “f”, the F value “Fno.”, the half angle of view “ω”, the image height “Y”, and the total optical length “TL” of the zoom lens at the time of focusing at infinity. .. However, in Table 2, the values at the wide-angle end, the intermediate focal length state, and the telephoto end are shown in order from the left side.

Table 3 shows variable intervals on the optical axis of the zoom lens at the time of zooming. In Table 3, the values at the wide-angle end, the intermediate focal length state, and the infinity focus state at the telephoto end are shown in order from the left side. In the table, “INF” indicates “∞ (infinity)”.

Table 4 shows the variable intervals on the optical axis of the zoom lens at the time of focusing. Table 4 shows values when the shooting distance (imaging distance) is 2900.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance at each focal length.

Table 5 shows the focal length of each lens group forming the zoom lens.

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).

The matters relating to these tables are the same in each table shown in other embodiments, and therefore the description thereof will be omitted below.

[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
7 302 0.7490 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

[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

[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

[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

[Table 5]
Group 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

2 to 4 are longitudinal aberration diagrams of the zoom lens of Embodiment 1 at the wide-angle end, the intermediate focal length state, and the telephoto end when focused on infinity, respectively. The longitudinal aberration charts shown in the respective figures are spherical aberration (mm), astigmatism (mm), and distortion (%) in order from the left side of the drawing. In the diagram showing spherical aberration, the vertical axis represents the ratio to the open F value, the horizontal axis represents defocus, the solid line represents the d line (wavelength λ=587.6 nm), and the alternate long and short dash line represents the g line (wavelength λ=435.8 nm). ), and the dotted line shows the spherical aberration at the C line (wavelength λ=656.3 nm). In the diagram showing astigmatism, the vertical axis represents image height and the horizontal axis represents defocus. The solid line represents the sagittal image surface (ds) for the d line, and the dotted line represents the meridional image surface (dm) for the d line. In the diagram showing the distortion aberration, the vertical axis shows the image height and the horizontal axis shows% to show the distortion aberration. The matters relating to these longitudinal aberration diagrams are the same in the longitudinal aberration diagrams shown in the other examples, and therefore the description thereof will be omitted below.

Further, the back focus “BFw” at the time of focusing on infinity at the wide angle end of the zoom lens is as follows. However, the following values do not include the cover glass (Nd=1.5168), and the same applies to the back focus shown in other examples.
BFw = 56.1827 (mm)

(1) Optical Configuration of Zoom Lens FIG. 5 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 2 according to the present invention at the wide-angle end when focused on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a positive lens group G3. The fourth lens group G4 having a negative refractive power, the fifth lens group G5 having a negative refractive power, and the sixth lens group G6 having a negative refractive power. The aperture stop S is arranged on the object side of the sixth lens group G6. 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, and the sixth lens group G6. The lens group Gp having a positive refractive power is the third lens group G3. The rear group includes 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 a third lens group G3, a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6.

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

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

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

The fourth lens group G4 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape on the object side and a biconvex lens L14 are cemented. The negative meniscus lens L13 having a convex shape on the object side is the lens Lnr according to the present invention.

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

The sixth lens group G6 includes, in order from the object side, an aperture stop S, a cemented lens in which a negative meniscus lens L17 having a convex shape in the object side and a biconvex lens L18 are cemented, and a cemented lens in which a convex lens L19 and a biconcave lens L20 are cemented. And a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented, a lens L23 which is a parallel plate having no substantial refracting power, and a cemented lens in which a biconvex lens L24 and a biconcave lens L25 are cemented. Has been done. The lens L23 is an insertion filter.

In the zoom lens of Embodiment 2, upon zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction with respect to the image plane, and the second lens group G2 moves toward the image side. The third lens group G3 moves so as to draw a convex locus on the image side, the fourth lens group G4 is fixed in the optical axis direction, and the fifth lens group G5 moves so as to draw a convex locus on the image side. The sixth lens group G6 is fixed in the optical axis direction.

In the present embodiment, the fifth lens group G5 is moved with respect to the fourth lens group G4 so as to draw a convex locus on the image side at the time of zooming from the wide-angle end to the telephoto end, thereby achieving good intermediate focal length. Secures good image quality.

In addition, in the present embodiment, the cemented lens in which the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 are cemented is an image stabilization group, and the image stabilization group is moved in the direction perpendicular to the optical axis to cause camera shake or the like. It is preferable to shift the image when it occurs to correct the image blur.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 6 shows surface data of the zoom lens, and Table 7 shows a specification table of the zoom lens. The 46th and 47th surfaces in Table 6 are surface data of the insertion filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

Table 8 shows the variable distance on the optical axis of the zoom lens at the time of zooming, and Table 9 shows the variable distance on the optical axis of the zoom lens at the time of focusing. Table 9 shows values when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance at each focal length.

Table 10 shows the focal length of each lens group forming the zoom lens. 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).

6 to 8 are longitudinal aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at the intermediate focal length state, and at the telephoto end when focused on infinity, respectively.

Further, the back focus at the wide angle end of the zoom lens at infinity is as follows.
BFw = 47.6948 (mm)

[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

[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

[Table 8]
f 204.385 383.887 583.896
Shooting 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

[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

[Table 10]
Group 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

(1) Optical Configuration of Zoom Lens FIG. 9 is a lens cross-sectional view showing the lens configuration of the zoom lens of Example 3 according to the present invention at the wide-angle end when focused on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a positive lens group G3. The fourth lens group G4 having a negative refractive power, the fifth lens group G5 having a negative refractive power, and the sixth lens group G6 having a negative refractive power. The aperture stop S is arranged on the object side of the sixth lens group G6. 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, and the sixth lens group G6. The lens group Gp having a positive refractive power is the third lens group G3. The rear group includes 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 a third lens group G3, a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6.

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

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

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

The fourth lens group G4 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape on the object side and a biconvex lens L14 are cemented. The negative meniscus lens L13 having a convex shape on the object side is the lens Lnr according to the present invention.

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

The sixth lens group G6 includes, in order from the object side, an aperture stop S, a cemented lens in which a negative meniscus lens L17 having a convex shape in the object side and a biconvex lens L18 are cemented, and a cemented lens in which a convex lens L19 and a biconcave lens L20 are cemented. And a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented, a lens L23 which is a parallel plate having no substantial refracting power, and a cemented lens in which a biconvex lens L24 and a biconcave lens L25 are cemented. Has been done. The lens L23 is an insertion filter.

In the zoom lens of Embodiment 3, upon zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction with respect to the image plane, and the second lens group G2 moves toward the image side. The third lens group G3 moves so as to draw a convex locus on the image side, the fourth lens group G4 is fixed in the optical axis direction, and the fifth lens group G5 moves so as to draw a convex locus on the image side. The sixth lens group G6 is fixed in the optical axis direction.

In the present embodiment, the fifth lens group G5 is moved with respect to the fourth lens group G4 so as to draw a convex locus on the image side at the time of zooming from the wide-angle end to the telephoto end, thereby achieving good intermediate focal length. Secures good image quality.

In addition, in the present embodiment, the cemented lens in which the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 are cemented is an image stabilization group, and the image stabilization group is moved in the direction perpendicular to the optical axis to cause camera shake or the like. It is preferable to shift the image when it occurs to correct the image blur.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 11 shows surface data of the zoom lens, and Table 12 shows a specification table of the zoom lens. The 46th and 47th surfaces in Table 11 are surface data of the insertion filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

Table 13 shows the variable distance on the optical axis of the zoom lens at the time of zooming, and Table 14 shows the variable distance on the optical axis of the zoom lens at the time of focusing. Table 14 shows values at the wide-angle end, the intermediate focal length state, and the telephoto end when the shooting distance (imaging distance) is 2900.00 mm. This value is the shortest imaging distance at each focal length.

Table 15 shows the focal length of each lens group forming the zoom lens. 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).

10 to 12 are longitudinal aberration diagrams of the zoom lens of Example 2 at the wide-angle end, the intermediate focal length state, and the telephoto end when focused on infinity, respectively.

Further, the back focus at the wide angle end of the zoom lens at infinity is as follows.
BFw = 56.1739 (mm)

[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

[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

[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

[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

[Table 15]
Group 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

(1) Optical Configuration of Zoom Lens FIG. 13 is a lens cross-sectional view showing the lens configuration of the zoom lens of Embodiment 4 according to the present invention at the wide-angle end when focused on infinity. The zoom lens includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a positive lens group G3. From the fourth lens group G4 having a negative refractive power, the fifth lens group G5 having a positive refractive power, the sixth lens group G6 having a negative refractive power, and the seventh lens group G7 having a negative refractive power. It is configured. At the time of focusing from an object at infinity to a near object, the sixth lens group G6 moves to the image side along the optical axis. The aperture stop S is arranged on the object side of the seventh lens group G7. In this embodiment, the rear group includes 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. Composed. The lens group Gp having a positive refractive power is the fourth lens group G4. The rear group includes 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 a third lens group G3, a fourth lens group G4, a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7.

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

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

The third lens group G3 is composed of a biconvex lens L9. The biconvex lens L9 is the lens Lrp according to the present invention, and ΔPgFLrp is 0.0564.

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

The fifth lens group G5 is composed of a cemented lens in which a negative meniscus lens L13 having a convex shape on the object side and a biconvex lens L14 are cemented. The negative meniscus lens L13 having a convex shape on the object side is the lens Lnr according to the present invention.

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

The seventh lens group G7 includes, in order from the object side, an aperture stop S, a cemented lens in which a negative meniscus lens L17 having a convex shape in the object side and a biconvex lens L18 are cemented, and a cemented lens in which a convex lens L19 and a biconcave lens L20 are cemented. And a cemented lens in which a biconvex lens L21 and a biconcave lens L22 are cemented, a lens L23 which is a parallel plate having no substantial refracting power, and a cemented lens in which a biconvex lens L24 and a biconcave lens L25 are cemented. Has been done. The lens L23 is an insertion filter.

In the zoom lens of Embodiment 4, upon zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction with respect to the image plane, and the second lens group G2 moves toward the image side. The third lens group G3 moves so as to draw a convex locus on the image side, the fourth lens group G4 moves so as to draw a convex locus on the image side, and 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 on the image side, and the seventh lens group G7 is fixed in the optical axis direction.

In this embodiment, the sixth lens group G6 is moved with respect to the fifth lens group G5 so as to draw a convex locus on the image side at the time of zooming from the wide-angle end to the telephoto end, thereby achieving good intermediate focal length. Secures good image quality.

In addition, in the present embodiment, the cemented lens in which the convex lens L19 and the biconcave lens L20 included in the sixth lens group G6 are cemented is an image stabilization group, and the image stabilization group is moved in the direction perpendicular to the optical axis to cause camera shake or the like. It is preferable to shift the image when it occurs to correct the image blur.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 16 shows surface data of the zoom lens, and Table 21 shows a specification table of the zoom lens. Note that the 46th and 47th surfaces in Table 16 are surface data of the insertion filter, and the 52nd and 53rd surfaces are surface data of the cover glass CG.

Table 18 shows the variable distance on the optical axis of the zoom lens at the time of zooming, and Table 19 shows the variable distance on the optical axis of the zoom lens at the time of focusing. Table 14 shows values when the shooting distance (imaging distance) is 2500.00 mm at the wide-angle end, the intermediate focal length state, and the telephoto end. This value is the shortest imaging distance at each focal length.

Table 20 shows the focal length of each lens group that constitutes the zoom lens. 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).

14 to 16 are longitudinal aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate focal length state, and the telephoto end, respectively, at the time of focusing at infinity.

Further, the back focus at the wide angle end of the zoom lens at infinity is as follows.
BFw = 48.0568 (mm)

[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

[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

[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

[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

[Table 20]
Group 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

[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
Conditional expression (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

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

G1... First lens group G2... Second lens group G3... Third lens group G4... Fourth lens group G5... Fifth lens group G6... Sixth lens group G7... ..Seventh lens group S... Aperture stop CG... Cover glass IMG... Imaging plane

Claims (16)

The first lens group having a positive refracting power and the rear group including at least one lens group Gp having a positive refracting power are arranged in this order from the object side. By changing the air gap between the adjacent lens groups, Scales,
The first lens group has 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,
A zoom lens that satisfies the following conditional expression.
3.50 <ft/fnot/Y <9.00 (...)
63.0<νdL1p1<76.0 (2)
32.0 <νdLpn <65.0 (3)
However,
ft: focal length of the zoom lens at the telephoto end fnot: F value of the zoom lens at the telephoto end Y: maximum image height of the zoom lens νdL1p1: Abbe's number at the d line of the lens L1p1 νdLpn: d line of the lens Lpn Abbe number in The zoom lens according to claim 1, wherein the following conditional expressions are satisfied.
0.25 <f1/ft <0.65 (4)
However,
f1: focal length of the first lens group The zoom lens according to claim 1, wherein the first lens group is fixed in the optical axis direction with respect to the image plane during zooming. The zoom lens according to any one of claims 1 to 3, wherein the rear group has a lens group R closest to the image side, and the lens group R has a negative refractive power. The zoom lens according to any one of claims 1 to 4, wherein the rear group has a lens group R closest to the image side, and the lens group R satisfies the following conditional expression.
1.20 <βRT <2.50 (5)
However,
βRT: Lateral magnification of the lens unit R at the telephoto end 6. The rear group has a lens group R closest to the image side, and the lens group R is fixed in the optical axis direction with respect to the image plane during zooming. The zoom lens according to item. The rear group has a lens group R closest to the image side thereof, and has at least one lens group having a negative refractive power on the object side of the lens group R,
The following conditional expression is satisfied when a lens group having negative refracting power which is arranged closest to the image side among the lens groups having negative refracting power included in the rear group is defined as a negative lens group n. The zoom lens according to any one of claims 1 to 6.
2.50 <βnRT <6.00 (6)
However,
βnRT: Composite lateral magnification at the telephoto end from the negative lens group n to the lens group R 8. The zoom lens according to claim 7, wherein the negative lens group n is a focus group capable of focusing on a near subject by moving in the optical axis direction. The zoom lens according to any one of claims 1 to 8, which has a diaphragm closer to the image side than the lens group Gp. The zoom lens according to any one of claims 1 to 9, wherein the first lens group includes a lens L1n having a negative refractive power and satisfies the following conditional expression.
1.79 <NdL1n <1.92 (7)
However,
NdL1n: Refractive index of the lens L1n at d line The zoom lens according to any one of claims 1 to 10, wherein the rear group includes at least one lens Lrp having a positive refractive power and satisfies the following conditional expression.
0.010 <ΔPgFLrp <0.070 (8)
However,
ΔPgFLrp: Anomalous dispersion of the lens having the largest anomalous dispersion among the lenses Lrp included in the rear group, where anomalous dispersion is C7 (partial dispersion ratio: 0.5393, νd: 60.49) And F2 (partial dispersion ratio: 0.5829, νd: 36.30) and the deviation of the partial dispersion ratio from the reference line when a straight line passing through the coordinates of νd is used as the reference line. The zoom lens according to any one of claims 1 to 11, which satisfies the following conditional expression.
0.80 <f1/fw <3.00 (9)
However,
f1: focal length of the first lens group fw: focal length of the zoom lens at the wide-angle end The zoom lens according to any one of claims 1 to 12, wherein the rear group includes at least one lens Lnr having a negative refractive power and satisfies the following conditional expression.
1.83 <NdLnr <2.20 (10)
However,
NdLnr: Refractive index of the lens Lnr at d line The zoom lens according to any one of claims 1 to 13, which satisfies the following conditional expression.
0.80 <BFw/(fw×tanωw) <4.50 (11)
However,
BFw: Air equivalent length at the wide-angle end from the lens surface closest to the image side to the image plane of the zoom lens fw: Focal length of the zoom lens at the wide-angle end ωw: Outmost axis of the zoom lens at infinity at the wide-angle end Half-angle of chief ray The zoom lens according to any one of claims 1 to 14, which satisfies the following conditional expression.
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 A zoom lens according to any one of claims 1 to 15, and an image sensor for converting an optical image formed by the zoom lens into an electric signal on an image side of the zoom lens. A characteristic imaging device.

Images