Variable magnification optical system and imaging device

Abstract

The problem is to provide a zoom optical system and an imaging device with high imaging performance and small size. The solution is that the zoom optical system is composed of a positive first lens group (G1), a negative second lens group (G2), a positive third lens group (G3), and a rear group in order from the object side, the rear group has a negative lens group (N) and a positive lens group (P), the positive lens group (P) is arranged adjacent to the image side of the negative lens group (N), during zooming from the wide-angle end to the telephoto end, the first lens group (G1) and the third lens group (G3) are fixed relative to the image plane, the second lens group (G2) moves toward the image side, the negative lens group (N) and the positive lens group (P) move with different trajectories, in addition, the interval between adjacent lens groups changes during zooming, and a specified condition is satisfied. In addition, the imaging device is provided with the zoom optical system and an imaging element.

Description

TECHNICAL FIELD

[0001] The present application relates to a zoom optical system and an image pickup apparatus, and particularly to a zoom optical system and an image pickup apparatus suitable for an image pickup apparatus using a solid-state image pickup element (CCD, CMOS, etc.) such as a digital still camera, a digital video camera, etc. BACKGROUND

[0002] In recent years, image pickup apparatuses using a solid-state image pickup element (hereinafter referred to as "image pickup element") such as a CCD, a CMOS, etc. have been increasingly popular. For example, in addition to a single-lens reflex camera, a mirrorless single-lens camera, a digital still camera, etc. which can be carried by a user, a surveillance-use image pickup apparatus, a vehicle-mounting-use image pickup apparatus, etc. which are fixedly installed to a building or a vehicle body, etc. and used for a specific purpose such as a surveillance use are also being increasingly popular. In either kind of image pickup apparatus, remarkable progress in high performance and miniaturization thereof is being made, and also with respect to an optical system used in these image pickup apparatuses, further high performance and miniaturization, etc. are required.

[0003] A zoom optical system is widely used in these image pickup apparatuses because it can change a photographing magnification in accordance with a position of a subject, etc. With the high performance and miniaturization of the image pickup apparatuses, with respect to the zoom optical system, it is also required to achieve a high zoom ratio and high resolution performance and miniaturization. In particular, in recent years, high pixelization and large-sizing of the image pickup element are also remarkable. Therefore, with respect to the zoom optical system, it is required to achieve higher resolution performance and further miniaturization. Further, the miniaturization of the optical system in the present specification includes, for example, the relative meaning of the miniaturization of the optical system when the image pickup element is larger than ever before while the size of the optical system is maintained to be the same degree as ever before, etc. Furthermore, not only in the fixedly installed image pickup apparatuses but also in the portable image pickup apparatuses, it is required that the barrel structure of the optical system is excellent in dustproof and drip-proof and is robust.

[0004] In response to such a requirement, in the zoom optical system of the fixedly installed image pickup apparatuses in the past, a lens group configuration in which a positive 1st lens group, a negative 2nd lens group, a positive 3rd lens group, a negative 4th lens group, and a positive 5th lens group are sequentially arranged from an object side has been mainly adopted, and in zooming, the 1st lens group, the 3rd lens group, and the 5th lens group are fixed with respect to an image plane, the 2nd lens group and the 4th lens group are moved, and in focusing, the 4th lens group is moved in accordance with a change in photographing distance (for example, refer to Patent Documents 1 to 3). Such a zoom optical system in which the 2nd lens group is a variator and the 4th lens group is a compensator is easy to increase the zoom ratio and miniaturize the entire system.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT DOCUMENTS

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-352183

[0008] [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-133738

[0009] [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-207665 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, for example, in the embodiments 1 to 6 of the above Patent Document 1, Patent Document 2, and Patent Document 3, in order to concentrate the power changing action on the 2nd lens group, a relatively large power is provided to the 2nd lens group. Therefore, if the power provided to the 2nd lens group is made larger in order to realize a power changing optical system with a higher power changing ratio and a smaller size, there is a problem that it is difficult to correct aberration occurring in the 2nd lens group and it is difficult to realize high resolution performance.

[0012] On the other hand, in the power changing optical systems of the embodiments 1 to 3 of Patent Document 3, the power changing action is avoided from being concentrated on the 2nd lens group. However, in these power changing optical systems, the total length at the wide angle end is relatively long with respect to the focal length, and the size at the wide angle end is not sufficiently small. Therefore, in the case where it is intended to maintain the maximum field angle equivalent to that of the power changing optical systems of the embodiments 1 to 3 of Patent Document 3 and to make it correspond to a larger imaging device, there is a problem that the entire system becomes large in these power changing optical systems.

[0013] The present application has been made in view of the above-described circumstances, and has an object to provide a power changing optical system and an imaging device which are small in size and have high resolution performance.

[0014] MEANS FOR SOLVING THE PROBLEMS

[0015] In order to solve the above-described problems, a power changing optical system according to the present application is characterized by being composed of, in order from the object side, a 1st lens group having a positive power, a 2nd lens group having a negative power, a 3rd lens group having a positive power, and a rear group, the rear group being composed of a negative lens group N having a negative power and a positive lens group P having a positive power, the positive lens group P being disposed adjacent to the image side of the negative lens group N, the 1st lens group and the 3rd lens group being fixed with respect to the image plane, the 2nd lens group moving toward the image side, the negative lens group N and the positive lens group P moving with different trajectories from each other, the interval between the adjacent lens groups changing at the time of power changing, and the following conditional expression being satisfied.

[0016] 1.4 ≤ βpt / βpw ≤ 4.0 ··· (1)

[0017] 7.0 ≤ TL / fw ≤ 20.0 ··· (2)

[0018] wherein,

[0019] βpt: lateral magnification of the positive lens group P at the telephoto end

[0020] βpw: lateral magnification of the positive lens group P at the wide angle end

[0021] TL: sum of a distance on an optical axis from a most object side surface to a most image side surface of the variable power optical system and an air conversion length from the most image side surface to an image plane

[0022] fw: focal length of the variable power optical system at the wide angle end

[0023] Further, in order to solve the above problem, the imaging device according to the present application is characterized by comprising: the above variable power optical system, and an imaging element that converts an optical image formed by the variable power optical system into an electric signal.

[0024] Effects of the Invention

[0025] According to the present application, it is possible to provide a variable power optical system and an imaging device that are small in size and have high imaging performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a lens sectional view of the variable power optical system of Embodiment 1, (wide angle) indicates a wide angle end state, (intermediate) indicates an intermediate focus position state, and (telephoto) indicates a telephoto end state (the same applies to other lens sectional views).

[0027] Figure 2 is a longitudinal aberration diagram in the wide angle end state of Embodiment 1.

[0028] Figure 3 is a longitudinal aberration diagram in the intermediate focus position state of Embodiment 1.

[0029] Figure 4 is a longitudinal aberration diagram in the telephoto end state of Embodiment 1.

[0030] Figure 5 is a lens sectional view of the variable power optical system of Embodiment 2.

[0031] Figure 6 is a longitudinal aberration diagram in the wide angle end state of Embodiment 2.

[0032] Figure 7 is a longitudinal aberration diagram in the intermediate focus position state of Embodiment 2.

[0033] Figure 8 is a longitudinal aberration diagram in the telephoto end state of Embodiment 2.

[0034] Figure 9 is a lens configuration diagram of the zoom optical system of Embodiment 3 of the present application.

[0035] Figure 10 is a longitudinal aberration diagram in a wide-angle end state of Embodiment 3.

[0036] Figure 11 is a longitudinal aberration diagram in an intermediate focus position state of Embodiment 3.

[0037] Figure 12 is a longitudinal aberration diagram in a telephoto end state of Embodiment 3.

[0038] Figure 13 is a lens configuration diagram of the zoom optical system of Embodiment 4 of the present application.

[0039] Figure 14 is a longitudinal aberration diagram in a wide-angle end state of Embodiment 4.

[0040] Figure 15 is a longitudinal aberration diagram in an intermediate focus position state of Embodiment 4.

[0041] Figure 16 is a longitudinal aberration diagram in a telephoto end state of Embodiment 4.

[0042] Figure 17 is a lens configuration diagram of the zoom optical system of Embodiment 5 of the present application.

[0043] Figure 18 is a longitudinal aberration diagram in a wide-angle end state of Embodiment 5.

[0044] Figure 19 is a longitudinal aberration diagram in an intermediate focus position state of Embodiment 5.

[0045] Figure 20 is a longitudinal aberration diagram in a telephoto end state of Embodiment 5.

[0046] Explanation of Reference Numerals:

[0047] G1 ··· 1st lens group

[0048] G2 ··· 2nd lens group

[0049] G3 ··· 3rd lens group

[0050] G4 ··· 4th lens group

[0051] G5 ··· 5th lens group

[0052] G6 ··· 6th lens group

[0053] G7 ··· 7th lens group

[0054] F ··· focusing lens group

[0055] S... aperture stop

[0056] CG... cover glass

[0057] IP... image plane DETAILED DESCRIPTION

[0058] Hereinafter, an embodiment of a zoom optical system and an image pickup apparatus according to the present application will be described. However, the zoom optical system and the image pickup apparatus described hereinafter are one mode of the zoom optical system and the image pickup apparatus according to the present application, and the zoom optical system and the image pickup apparatus according to the present application are not limited to the mode described hereinafter.

[0059] 1. Zoom optical system

[0060] 1-1. Optical configuration

[0061] The zoom optical system is configured of, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group. The rear group is configured of a negative lens group N having negative refractive power and a positive lens group P having positive refractive power, and the positive lens group P is disposed adjacent to the image side of the negative lens group N. Here, the lens groups are configured of one or more lenses, and the interval between the adjacent lens groups changes during zooming. In the zoom optical system, during zooming from the wide-angle end to the telephoto end, the first lens group and the third lens group are fixed with respect to the image plane, the second lens group moves toward the image side, and the negative lens group N and the positive lens group P move along trajectories different from each other.

[0062] In the zoom optical system, the first lens group and the third lens group having positive refractive power are fixed with respect to the image plane during zooming, and the second lens group having negative refractive power located therebetween is moved. The configuration in which such a front group is configured (positive-negative-positive) and the second lens group is used as a variator is effective in correcting aberration and achieving a high zoom ratio. As a zoom optical system in which such a configuration has been adopted in the past, as described above, a zoom optical system configured of five groups having positive-negative-positive-negative-positive refractive power configurations in order from the object side is known. However, in the past zoom optical system, not only the first lens group and the third lens group having positive refractive power but also the fifth lens group having positive refractive power are fixed with respect to the image plane, the second lens group is used as a variator, the fourth lens group is used as a compensator, and thus the zooming action is concentrated on the second lens group, and the imaging position is corrected by the fourth lens group. In order to adopt this configuration and achieve further miniaturization and higher zooming than in the past, it is necessary to configure the second lens group with stronger negative refractive power. In this case, it is difficult to correct the aberration occurring in the second lens group, and it is difficult to achieve a large aperture or higher imaging performance.

[0063] On the other hand, in this zoom optical system, the front group is configured with the aforementioned three groups of positive, negative, and positive lenses. The rear group, positioned further from the image side than the third lens group, consists of a negative lens group N and a positive lens group P arranged sequentially adjacent to each other from the object side. During zooming, the negative lens group N and the positive lens group P move along separate, independent trajectories. In other words, in this zoom optical system, zooming is distributed not only to the second lens group but also to the rear group. Therefore, while achieving miniaturization and high zoom, excessive negative optical power in the second lens group is suppressed, and aberration balance is easily maintained throughout the system. This allows for high resolving performance across the entire zoom range while maintaining a compact zoom optical system.

[0064] Furthermore, by configuring the front group as described above, the first and third lens groups can be fixed, for example, to the same lens barrel. This stabilizes the relative eccentricity between the lens groups from the first to the third, suppressing performance degradation due to manufacturing errors. Additionally, with the first lens group as the fixed group, the lens barrel length does not change during zooming, making it easier to employ a lens barrel structure with excellent dust and drip resistance. Thus, a zoom optical system with excellent manufacturability and robustness can be obtained. The configuration of the front and rear groups will be described below. Furthermore, as mentioned above, in this specification, the first to third lens groups are conveniently referred to as the front group, and the lens groups arranged from the fourth lens group onwards are referred to as the rear group.

[0065] (1) Pre-group

[0066] The front group is composed of the first to third lens groups arranged sequentially from the object side, and the specific lens configuration of each lens group is not particularly limited. For example, from the viewpoint of effectively correcting chromatic aberration, it is preferable to appropriately combine lenses with suitable dispersion among positive and negative lenses.

[0067] (2) Rear group

[0068] The rear group is a collective term for lens groups arranged between the image side of the third lens group and the image plane, and as long as a negative lens group N and a positive lens group P are arranged in this order adjacent to each other from the object side, the number of lens groups included in the rear group, the power arrangement, and the like, and the specific lens group configuration are not particularly limited. The rear group can have a positive power or a negative power, but it is preferable that the rear group have a positive power at the wide-angle end. In addition, the rear group can be configured only by the negative lens group N and the positive lens group P, or can have one or more lens groups having a positive power on the object side of the negative lens group N, and can have one or more lens groups having a positive or negative power on the image side of the positive lens group P. In addition, the rear group can have two or more negative lens groups N and positive lens groups P. Specifically, the rear group can be configured to have a first negative lens group N, a first positive lens group P, a second negative lens group N, and a second positive lens group P in this order from the object side.

[0069] Further, the rear group preferably has a fixed group fixed with respect to the image plane during zooming at the most image-side thereof. In this zoom optical system, the lens group arranged at the most image-side is set as the fixed group fixed with respect to the image plane during zooming, so that the image plane side is easily configured to have an excellent dust and drip prevention performance. In this zoom optical system, the first lens group is the fixed group, so that by further arranging the fixed group at the most image-side, the most object-side and the most image-side are stably held in a lens barrel or the like, and a configuration having higher robustness can be provided.

[0070] (3) Aperture stop

[0071] In this zoom optical system, the arrangement of the aperture stop is not particularly limited. In this zoom optical system, the outer diameter of the lens group after the second lens group is smaller than that of the first lens group. Therefore, if the aperture stop is arranged after the second lens group, the diameter of the aperture stop can also be reduced, and the downsizing and weight reduction of the driving mechanism for opening and closing the aperture stop can be achieved. Therefore, this is also preferable in achieving the downsizing and weight reduction of the zoom optical system. In particular, in this zoom optical system, the third lens group is the fixed group, so that it is preferable to arrange the aperture stop adjacent to the object side or the image side of the third lens group or within the third lens group. If the aperture stop is arranged in this way in conjunction with the third lens group as the fixed group, it is not necessary to move the driving mechanism for opening and closing the aperture stop during zooming, so that a space for accommodating the driving mechanism for opening and closing the aperture stop can be easily ensured in the lens barrel, and the downsizing of the entire zoom optical system including the lens barrel can be achieved. In addition, in this case, the aperture stop and the mechanism for opening and closing the aperture stop can be fixed with respect to the image plane during zooming together with the third lens group, so that a configuration having high robustness can be provided. Further, the aperture stop is arranged in the vicinity of the third lens group, which is also preferable in terms of aberration correction.

[0072] 1-2. Action

[0073] (1) Action at the time of zooming

[0074] As described above, at the time of zooming from the wide angle end to the telephoto end, the first lens group and the third lens group are fixed with respect to the image plane, the second lens group moves toward the image side, and the negative lens group N and the positive lens group P of the rear group move along different trajectories from each other. At this time, when the lens group disposed at the most image side of the rear group is other than the positive lens group P, it is preferable that the lens group disposed at the most image side of the rear group be fixed with respect to the image plane as described above.

[0075] (2) Action at the time of focusing

[0076] In this zoom optical system, by moving a certain lens group or a part thereof along the optical axis in correspondence with the change in photographing distance, it is possible to focus on the subject. At this time, which lens group or a part thereof is used as the focusing group that moves along the optical axis at the time of focusing is not particularly limited, but it is preferable that the above-mentioned negative lens group N or the positive lens group disposed in the rear group be used as the focusing group. These lens groups can be made smaller in outer diameter compared to other lens groups, and can achieve miniaturization and lightening of the focusing group. In this configuration, generally, the negative lens group N is easier to lighten than the positive lens group P. Therefore, in order to achieve miniaturization and lightening of the focusing group and achieve rapid control, it is preferable that the negative lens group N be used as the focusing group.

[0077] 1-3. Conditional expressions

[0078] In this zoom lens, it is preferable that not only the above-mentioned configuration be adopted, but also one or more of the conditional expressions described below be satisfied.

[0079] 1-3-1. Conditional expression (1)

[0080] 1.4 ≤ βpt / βpw ≤ 4.0...(1)

[0081] wherein,

[0082] βpt: lateral magnification of the positive lens group P at the telephoto end

[0083] βpw: lateral magnification of the positive lens group P at the wide angle end

[0084] The conditional expression (1) is an expression that defines the ratio of the lateral magnification of the positive lens group P at the telephoto end to the lateral magnification of the positive lens group P at the wide-angle end of the variable magnification optical system. That is, it is an expression that defines the variable magnification ratio of the positive lens group P. By satisfying the conditional expression (1), the variable magnification effect can be distributed to the positive lens group P, and the concentration of the variable magnification effect to the second lens group can be suppressed. Therefore, when it is desired to make the variable magnification ratio of the variable magnification optical system higher or to achieve further miniaturization, the negative power arranged to the second lens group can be suppressed from being too strong, and the aberration correction can be performed well in the entire variable magnification region. As a result, a variable magnification optical system that is small in overall configuration, has high image-forming performance, and has a higher variable magnification ratio can be achieved.

[0085] On the contrary, if the value of the conditional expression (1) is less than the lower limit value, it is difficult to sufficiently distribute the variable magnification effect to the positive lens group P. As a result, the variable magnification effect is concentrated in the second lens group, and it is difficult to suppress the aberration, particularly the coma at the wide-angle end side, generated in the second lens group. On the other hand, if the value of the conditional expression (1) exceeds the upper limit value, the distribution of the variable magnification effect to the positive lens group P is large, and it is difficult to suppress the aberration, particularly the spherical aberration, generated in the positive lens group P.

[0086] In terms of achieving these effects, the lower limit value of the conditional expression (1) is more preferably 1.5, further preferably 1.6, and more further preferably 1.7. In addition, the upper limit value of the conditional expression (1) is more preferably 3.6, further preferably 3.3, more further preferably 3.0, and still further preferably 2.8. Furthermore, in the case where these preferred lower limit values or upper limit values are adopted, the inequality sign (=) in the conditional expression (1) can be replaced with an inequality sign (<). The same applies to other conditional expressions.

[0087] 1-3-2. Conditional expression (2)

[0088] 7.0 ≤ TL / fw ≤ 20.0... (2)

[0089] wherein,

[0090] TL: the sum of the distance on the optical axis from the most object side surface to the most image side surface and the air converted length from the most image side surface to the image surface of the variable magnification optical system

[0091] fw: the focal length of the variable magnification optical system at the wide-angle end

[0092] Here, the most object side surface and the most image side surface refer to the lens surfaces that substantially constitute the variable magnification optical system, that is, the lens surfaces that substantially have a power.

[0093] The sum of the distance on the optical axis of the variable magnification optical system from the most object side surface to the most image side surface and the air converted length from the most image side surface to the image plane means the total optical length of the variable magnification optical system. That is, the above conditional expression (2) is an expression that defines the ratio of the total optical length of the variable magnification optical system to the focal length of the variable magnification optical system at the wide angle end. By satisfying the conditional expression (2), the power configuration becomes a reverse focus type at the wide angle end, a high magnification ratio can be achieved, and the total optical length is suppressed from being too long. In this case, the power of the lens group configuration that bears the variable magnification function is suppressed from being too strong, and aberration correction is favorably performed over the entire variable magnification region. Thus, a variable magnification optical system that is small in size as a whole, has high image resolution, and has a higher magnification ratio can be achieved.

[0094] On the other hand, if the value of the conditional expression (2) is less than the lower limit value, the power of the lens group that bears the variable magnification function becomes strong relative to the total optical length. Therefore, if a variable magnification optical system with a higher magnification ratio is desired, it is difficult to correct aberration, particularly coma and field curvature, and it is difficult to obtain a variable magnification optical system with high image resolution. In addition, if the value of the conditional expression (2) exceeds the upper limit value, the negative combined power of the first lens group and the second lens group at the wide angle end becomes strong, and thus it is difficult to correct spherical aberration.

[0095] In terms of achieving these effects, the lower limit value of the conditional expression (2) is more preferably 8.0, further preferably 10.0, more further preferably 12.0, and still further preferably 14.0. In addition, the upper limit value of the conditional expression (2) is more preferably 19.0, further preferably 18.0, and more further preferably 17.0.

[0096] 1-3-3. Conditional expression (3)

[0097] 0.3 ≤ βnt / βnw ≤ 0.8... (3)

[0098] wherein

[0099] βnt: lateral magnification of the negative lens group N at the telephoto end

[0100] βnw: lateral magnification of the negative lens group N at the wide angle end

[0101] The above conditional expression (3) is an expression that defines the ratio of the lateral magnification of the negative lens group N at the telephoto end to the lateral magnification of the negative lens group N at the wide angle end. That is, it is an expression that defines the magnification ratio of the negative lens group N. By satisfying the conditional expression (3), the magnification ratio of the negative lens group N is within an appropriate range, the variable magnification function can be allocated to the positive lens group P, and aberration correction is favorably performed over the entire variable magnification region. Thus, a variable magnification optical system that is small in size as a whole, has high image resolution, and has a higher magnification ratio can be achieved.

[0102] On the other hand, if the value of conditional expression (3) exceeds the upper limit value, it is difficult to correct aberration by the negative lens group N when the power changing effect is allocated to the positive lens group P, and thus it is difficult to achieve the balance of aberration of the entire system and to allocate the power changing effect to the positive lens group P. As a result, in order to achieve the prescribed power changing ratio, the power changing effect is concentrated in the second lens group, and it is difficult to correct aberration.

[0103] In terms of obtaining these effects, the lower limit value of conditional expression (3) is more preferably 0.35, further preferably 0.40, more further preferably 0.45, and still further preferably 0.50. In addition, the upper limit value of conditional expression (3) is more preferably 0.75, further preferably 0.70, more further preferably 0.65, and still further preferably 0.60.

[0104] 1-3-4. Conditional expression (4)

[0105] 5.0 < β2t / β2w < 14.0 (4)

[0106] wherein,

[0107] β2t: lateral magnification of the second lens group at the tele end

[0108] β2w: lateral magnification of the second lens group at the wide end

[0109] The above conditional expression (4) is an expression that prescribes the ratio of the lateral magnification of the second lens group at the tele end to the lateral magnification of the second lens group at the wide end of the power changing optical system. That is, it is an expression that prescribes the power changing ratio of the second lens group. By satisfying conditional expression (4), the power changing ratio of the second lens group is within an appropriate range, and it is possible to suppress the concentration of the power changing effect to the second lens group, and to perform aberration correction well in the entire power changing region. Thus, it is possible to achieve a power changing optical system that is small in size as a whole, has high image-forming performance, and has a higher power changing ratio.

[0110] On the other hand, if the value of conditional expression (4) exceeds the upper limit value, the power changing ratio of the second lens group becomes large. That is, the power changing effect is concentrated in the second lens group, and it is difficult to correct aberration.

[0111] In terms of obtaining these effects, the lower limit value of conditional expression (4) is more preferably 6.0, further preferably 7.0, still further preferably 8.0, yet further preferably 9.0. In addition, the upper limit value of conditional expression (4) is more preferably 13.0, further preferably 12.0, still further preferably 11.0.

[0112] 1-3-5. Conditional expression (5)

[0113] 4.5 ≤ |f1 / f2| ≤ 6.5... (5)

[0114] wherein,

[0115] f1: focal length of the first lens group

[0116] f2: focal length of the second lens group

[0117] The above conditional expression (5) is an expression that defines the ratio of the focal length of the first lens group to the focal length of the second lens group. By satisfying conditional expression (5), the power of light can be appropriately distributed in balance between the first lens group and the second lens group. Thus, the aberration can be well corrected in the entire zoom region, and the movement amount of the second lens group at the time of zooming is suppressed from becoming large. Thus, a zoom optical system that is small in size as a whole, has high image-forming performance, and has a higher zoom ratio can be achieved.

[0118] On the contrary, if the value of conditional expression (5) is less than the lower limit value, the power of light of the first lens group becomes relatively strong with respect to the second lens group. In this case, it is difficult to suppress the spherical aberration generated in the second lens group from the first lens group. Alternatively, the power of light of the second lens group becomes relatively weak with respect to the first lens group. In this case, in order to achieve high zooming, the movement amount of the second lens group at the time of zooming needs to be made large. Thus, the total track length becomes long, and it is difficult to achieve the small size of the zoom optical system. On the other hand, if the value of conditional expression (5) exceeds the upper limit value, the power of light of the first lens group becomes relatively weak with respect to the second lens group. In this case, in order to achieve high zooming, the distance on the optical axis between the first lens group and the second lens group on the telephoto end side needs to be made long, and the total track length becomes long. Thus, it is difficult to make the entire optical system small in size. Alternatively, the power of light of the second lens group becomes relatively strong with respect to the first lens group. In this case, it is difficult to suppress the aberration, particularly, the coma and the field curvature, generated in the second lens group.

[0119] In terms of obtaining these effects, the lower limit value of conditional expression (5) is more preferably 4.8, further preferably 5.0, still further preferably 5.2, yet further preferably 5.4. In addition, the upper limit value of conditional expression (5) is more preferably 6.4, further preferably 6.3, still further preferably 6.2, yet further preferably 6.1.

[0120] Here, in order to more preferably suppress the axial chromatic aberration on the telephoto end side, it is more preferable that the average of the Abbe numbers of all the positive lenses arranged in the first lens group be 70 or more.

[0121] In addition, in order to more preferably suppress the magnification chromatic aberration on the wide angle end side, it is preferable that the lens arranged from the second piece on the object side in the second lens group have a negative power with a biconcave shape and have an Abbe number of 70 or more.

[0122] 1-3-6. Condition formula (6)

[0123] 1.5 ≤ fn / f2 ≤ 3.5 ··· (6)

[0124] wherein fn is the focal length of the negative lens group N

[0125] fn: focal length of the negative lens group N

[0126] The above condition formula (6) is a formula that defines the ratio of the focal length of the negative lens group N to the focal length of the second lens group. By satisfying the condition formula (6), the power can be appropriately distributed in balance between the negative lens group N and the second lens group. Thus, the aberration can be well corrected in the entire zooming region, and the movement amount of the negative lens group N at the time of zooming is suppressed from becoming large. Therefore, a zoom optical system that is small in overall size, has high image-forming performance, and has a higher zoom ratio can be achieved.

[0127] On the other hand, if the value of the condition formula (6) exceeds the upper limit value, the power of the negative lens group N with respect to the second lens group becomes relatively weak. In this case, in order to achieve high zooming, the movement amount of the negative lens group N at the time of zooming needs to be made large. Thus, the optical total length becomes long, and it is difficult to achieve a small size of the zoom optical system.

[0128] In terms of achieving these effects, the lower limit value of the condition formula (6) is more preferably 2.0, further preferably 2.1, more further preferably 2.2, and still further preferably 2.3. In addition, the upper limit value of the condition formula (6) is more preferably 3.3, further preferably 3.2, more further preferably 3.1, and still further preferably 3.0.

[0129] Here, in order to more preferably suppress the chromatic aberration, it is preferable that the negative lens group N have a lens element in which a lens having a positive power and a lens having a negative power are bonded.

[0130] 1-3-7. Condition formula (7)

[0131] 1.1 ≤ |fp / f2| ≤ 2.5 ··· (7)

[0132] wherein,

[0133] fp: focal length of the positive lens group P

[0134] The conditional expression (7) is an expression that defines the ratio of the focal length of the positive lens group P to the focal length of the second lens group. By satisfying the conditional expression (7), the power of the positive lens group P and the second lens group can be distributed in a proper balance. Therefore, the aberration can be well corrected in the entire zoom region, and the movement amount of the positive lens group P at the time of zooming is suppressed from becoming large. Thus, a zoom optical system that is small in size as a whole, has high image-forming performance, and has a higher zoom ratio can be realized.

[0135] On the contrary, if the value of the conditional expression (7) is less than the lower limit value, the power of the positive lens group P with respect to the second lens group becomes relatively strong. In this case, it is difficult to suppress the spherical aberration generated in the positive lens group P. On the other hand, if the value of the conditional expression (7) exceeds the upper limit value, the power of the positive lens group P with respect to the second lens group becomes relatively weak. In this case, in order to realize a high zoom, the movement amount of the positive lens group P at the time of zooming needs to be made large, and the optical total track becomes long. Or, it is difficult to distribute the zoom ratio in a good balance among the lens groups.

[0136] In terms of obtaining these effects, the lower limit value of the conditional expression (7) is more preferably 1.3, further preferably 1.4, still further preferably 1.5, yet further preferably 1.6. In addition, the upper limit value of the conditional expression (7) is more preferably 2.3, further preferably 2.2, still further preferably 2.1, yet further preferably 2.0.

[0137] In order to better suppress the spherical aberration and the coma, it is preferable that the most object-ward surface in the positive lens group P is in a convex shape toward the object side, and the most image-ward surface is in a convex shape toward the image side. In addition, in order to better suppress the chromatic aberration, it is preferable that the average value of the Abbe numbers of all the positive lenses arranged in the positive lens group P is 70 or more.

[0138] 2. Imaging device

[0139] Next, an imaging device according to the present application will be described. The imaging device according to the present application is characterized by including the zoom optical system according to the present application described above, and an imaging element that converts an optical image formed by the zoom optical system into an electric signal. Further, the imaging element is preferably disposed on the image side of the zoom optical system.

[0140] In this embodiment, a solid-state imaging element such as a CCD (Charge Coupled Device) sensor, a CMOS (Complementary Metal Oxide Semiconductor) sensor, or the like can be used without particular limitation. The imaging device according to the present application is suitable for an imaging device such as a digital camera, a video camera, or the like that uses such a solid-state imaging element. In addition, the imaging device can be a fixedly installed imaging device such as a surveillance imaging device, a vehicle-mounted imaging device, or the like that is fixedly installed in a building or a vehicle body and used for a specific purpose such as a surveillance purpose, in addition to a portable imaging device such as a single-lens reflex camera, a mirrorless single-lens camera, a digital still camera, or the like that can be carried by a user. The imaging device can be either a lens-replaceable type or a fixed-lens type in which the lens is fixed to the housing. In particular, the zoom optical system according to the embodiment shown below has a high zoom ratio, is compact, and has high resolution, and thus if used as a zoom optical system of a surveillance camera or the like, a wide range can be monitored with one surveillance camera, and since the resolution is high, it is easy to enlarge and observe a surveillance object or to confirm a surveillance object in detail using image recognition technology.

[0141] Next, the present application will be described in detail with reference to the following embodiments. However, the present application is not limited to the following embodiments.

[0142] [Embodiment 1]

[0143] (1) Optical configuration of zoom optical system

[0144] Figure 1 is a lens sectional view of the zoom optical system according to Embodiment 1 of the present application. The zoom optical system is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. An aperture stop S is disposed on the object side of the third lens group G3, and a cover glass CG and an imaging surface IP are disposed on the image side of the sixth lens group G6. In the zoom optical system according to this embodiment, the fourth lens group G4 is the negative lens group N according to the present application, and the fifth lens group G5 is the positive lens group P according to the present application, and they are disposed adjacent to each other in order from the object side.

[0145] In this zoom optical system, as shown in Figure 1As shown, when zooming from the wide angle end to the telephoto end, the 1st lens group, the 3rd lens group and the 6th lens group are fixed with respect to the image plane, the 2nd lens group moves toward the image side, and the 4th lens group G4 (negative lens group N) and the 5th lens group G5 (positive lens group P) move toward the image side with different trajectories from each other. In addition, by moving the 4th lens group G4 (negative lens group N) toward the image side along the optical axis, focusing is performed from an infinite distance object to a close distance object. The specific lens configuration of each lens group is as follows Figure 1 and is shown by the surface data shown below.

[0146] (2) Numerical Example

[0147] Next, a numerical example regarding a specific numerical value of the lens will be described. Table 1 shows the surface data of the lens. In Table 1, "Surface No." indicates the serial number of the lens surface counted from the object side (surface number), "r" indicates the radius of curvature of the lens surface, "d" indicates the lens wall thickness or air gap on the optical axis, "nd" indicates the refractive index at the d-line (wavelength λ = 587.6 nm), and "vd" indicates the Abbe number at the d-line. In addition, in the column of "Surface No.", "*" attached after the surface number indicates that the lens surface is an aspherical surface, and "S" indicates that the surface is a stop. In the column of "d", the meaning indicated by "D1", "D2", and the like is that the interval on the optical axis of the lens surface is a variable interval that changes at the time of zooming. In addition, the meaning of "∞" in the column of the radius of curvature is infinity, meaning that the lens surface is a plane. In addition, the sign of the radius of curvature is set to be positive (+) in the case of being convex toward the object side. Furthermore, the unit of length in Table 1 and each table described below is "mm" throughout, and the unit of the field angle is "°" throughout.

[0148] Table 2 shows the aspherical coefficients of each aspherical surface. The aspherical surface is expressed by the following formula by defining x as the displacement amount from the vertex of the surface in the optical axis direction.

[0149] x = (h2 / r) / [1 + {1-(1+k)×(h / r)2}1 / 2)] + A4×h4 + A6×h6 + A8×h8 + A10×h10 + A12×h12

[0150] In the above formula, h indicates the height from the optical axis, r indicates the paraxial radius of curvature, k indicates the conic coefficient, and An indicates the aspherical coefficient of the n-th order. In Table 2, "E±XX" indicates the index mark, meaning "×10±XX".

[0151] Table 3 shows the elements of the variable magnification optical system. In Table 3, the focal length, Fno (F value), field angle, image height, total length (optical total length), and BF (back focus) of the variable magnification optical system at the wide-angle end, intermediate focus position, and telephoto end infinity object focus are shown. The values of the total length and BF are values when the thickness of the protective glass is converted to the air-equivalent length. The unit of length is set to mm, and the unit of angle is °. The matters related to these tables are the same in each table shown in other embodiments, and thus the explanation is omitted below. In addition, Table 3 shows the variable interval shown in Table 1. Further, Table 4 shows the focal length of each lens group, and Table 21 shows the values of each conditional expression.

[0152] [Table 1]

[0153]

[0154]

[0155] [Table 2]

[0156] Surface number k A4 A6 A8 A10 A12 13 0.0000 7.46838E-05 -1.25955E-06 1.25798E-08 -6.85502E-11 1.55066E-13 14 0.0000 6.06433E-05 -1.24840E-06 1.27321E-08 -7.07719E-11 1.64854E-13 16 0.0000 -8.55812E-06 5.53939E-08 -9.23413E-10 6.75807E-12 -2.34498E-14 17 0.0000 1.23434E-05 6.47121E-08 -9.48108E-10 6.80832E-12 -2.31945E-14 26 0.0000 -1.77569E-05 -7.93731E-08 1.05722E-09 -8.20983E-12 3.95510E-14 27 0.0000 1.84679E-05 -9.75954E-08 1.17735E-09 -6.09263E-12 2.54771E-14

[0157] [Table 3]

[0158]

[0159]

[0160] [Table 4]

[0161] Group Range Focal length G1 1-7 72.136 G2 8-14 -13.178 G3 15-22 24.866 G4 23-25 -31.186 G5 26-30 23.152 G6 31-32 -36.725 CG 33-34 ∞

[0162] In addition, Figures 2-4 The longitudinal aberration diagrams of the variable magnification optical system at the wide-angle end, intermediate focus position, and telephoto end infinity object focus are shown. The longitudinal aberration diagrams shown in each diagram are, in order from the left side of the drawing, the spherical aberration (mm), the coma (mm), and the distortion aberration (%), respectively. In the diagram showing the spherical aberration, the vertical axis is the proportion to the open F value, and the horizontal axis is the defocus, and Fno indicates the F value. "g" and "d" show the spherical aberration at the wavelengths of the g line (λ = 435.8 nm) and the d line (λ = 587.6 nm), respectively. In the coma diagram, the vertical axis is the half field angle, and the horizontal axis is the defocus, and ω indicates the half field angle (°), and dS shows the aberration in the sagittal direction, and dM shows the aberration in the meridional direction. In the distortion aberration diagram, the vertical axis is the half field angle, and the horizontal axis is the distortion aberration. In addition, the coma diagram and the distortion aberration diagram are the values at the d line. These matters are the same in each aberration diagram shown in other embodiments, and thus the explanation is omitted below.

[0163] [Embodiment 2]

[0164] (1) Optical configuration of variable magnification optical system

[0165] Figure 5 is a lens sectional view of the variable power optical system of Embodiment 2 to which the present application is applied. The variable power optical system is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, a sixth lens group G6 having positive power, and a seventh lens group G7 having negative power. An aperture stop S is disposed on the object side of the third lens group G3, and a cover glass CG and an image pickup plane IP are disposed on the image side of the seventh lens group G7. In the variable power optical system of this embodiment, the fifth lens group G5 is the negative lens group N of the present application, and the sixth lens group G6 is the positive lens group P of the present application, which are disposed adjacent to each other in order from the object side.

[0166] In the variable power optical system, as shown in Figure 5 , when zooming from the wide angle end to the telephoto end, the first lens group, the third lens group, and the seventh lens group are fixed with respect to the image plane, the second lens group moves toward the image side, and the fifth lens group G5 (negative lens group N) and the sixth lens group G6 (positive lens group P) move toward the image side with different trajectories from each other. In addition, by moving the fifth lens group G5 (negative lens group N) toward the image side along the optical axis, focusing from an infinite distance object to a close distance object is performed. The specific lens configuration of each lens group is shown by the surface data shown in Figure 5 and the following.

[0167] (2) Numerical Embodiment

[0168] Next, a numerical embodiment regarding the specific numerical values of the lens to which the present application is applied will be described. Table 5 shows the surface data of the lens. Table 6 shows the aspheric coefficients of each aspheric surface. Table 7 shows each element and variable interval of the variable power optical system. Further, Table 8 shows the focal length of each lens group, and Table 21 shows the values of each conditional expression. Further, Figures 6-8 shows the longitudinal aberration diagram of the variable power optical system at the wide angle end, at the intermediate focus position, and at the telephoto end when focusing on an infinite distance object.

[0169] [Table 5]

[0170]

[0171]

[0172]

[0173] [Table 6]

[0174] Surface number k A4 A6 A8 A10 A12 13 0.0000 7.75564E-05 -1.27413E-06 1.26805E-08 -6.91345E-11 1.58221E-13 14 0.0000 5.97271E-05 -1.25077E-06 1.25776E-08 -6.99302E-11 1.66486E-13 16 0.0000 -1.13302E-05 6.53790E-08 -8.54007E-10 6.03166E-12 -1.76041E-14 17 0.0000 1.37381E-05 7.39724E-08 -9.67272E-10 6.76552E-12 -1.92810E-14 27 0.0000 -2.01968E-05 -6.84038E-08 8.22309E-10 -7.00381E-12 1.74684E-14 28 0.0000 2.33723E-05 -6.49032E-08 1.41335E-09 -1.11953E-11 3.25849E-14

[0175] [Table 7]

[0176]

[0177]

[0178] [Table 8]

[0179] Group Surface number Focal length G1 1-7 71.752 G2 8-14 -12.946 G3 15-20 26.287 G4 21-23 3380.180 G5 24-26 -38.390 G6 27-31 20.882 G7 32-33 -25.614 CG 34-35 ∞

[0180] [Example 3]

[0181] (1) Optical configuration of variable magnification optical system

[0182] Figure 9 is a lens sectional view of the variable magnification optical system of Example 3 to which the present application is applied. The variable magnification optical system is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. An aperture stop S is disposed on the object side of the third lens group G3, and a cover glass CG and an image plane IP are disposed on the image side of the seventh lens group G7. In the variable magnification optical system of this example, the fifth lens group G5 is the negative lens group N of the present application, and the sixth lens group G6 is the positive lens group P of the present application, which are disposed adjacent to each other in order from the object side.

[0183] In this variable magnification optical system, as shown in Figure 9 , when zooming from the wide-angle end to the telephoto end, the first lens group, the third lens group, and the seventh lens group are fixed with respect to the image plane, the second lens group moves toward the image side, the fifth lens group G5 (negative lens group N) moves in a manner that traces a convex locus toward the image side, and the sixth lens group G6 (positive lens group P) moves toward the image side. In addition, by moving the fifth lens group G5 (negative lens group N) toward the image side along the optical axis, focusing is performed from an infinite distance object to a close distance object. The specific lens configuration of each lens group is shown by the surface data shown in Figure 9 and the following.

[0184] (2) Numerical example

[0185] Next, a numerical example regarding the specific numerical values of the lens will be described. Table 9 shows the surface data of the lens. Table 10 shows the aspheric coefficients of each aspheric surface. Table 11 shows each element and variable interval of the variable magnification optical system. Further, Table 12 shows the focal lengths of each lens group, and Table 21 shows the values of each conditional expression. Further, Figures 10-12 shows the longitudinal aberration diagrams of the variable magnification optical system at the wide-angle end, the intermediate focus position, and the telephoto end when focusing on an infinite distance object.

[0186] [Table 9]

[0187]

[0188]

[0189]

[0190] [Table 10]

[0191] Surface number k A4 A6 A8 A10 A12 13 0.0000 7.29149E-05 -1.28204E-06 1.23305E-08 -6.86173E-11 1.69804E-13 14 0.0000 5.54946E-05 -1.28113E-06 1.26757E-08 -7.22968E-11 1.86536E-13 16 0.0000 -1.48187E-05 3.57092E-08 -9.61147E-10 6.57801E-12 -2.07239E-14 17 0.0000 5.18396E-06 4.01670E-08 -9.86339E-10 6.70032E-12 -2.04049E-14 28 0.0000 -1.05583E-05 -5.99651E-08 1.11737E-09 -8.05158E-12 3.96181E-14 29 0.0000 3.91142E-05 -1.15509E-07 1.11973E-09 -4.55839E-12 1.97326E-14

[0192] [Table 11]

[0193] Wide angle Intermediate Telephoto Focal length 9.785 47.502 175.083 Fno 1.65 2.45 3.50 Field of view 70.802 15.076 4.203 Image height 6.50 6.50 6.50 Total length 161.103 161.103 161.103 BF 6.309 6.309 6.309 D1 0.801 32.684 47.016 D2 47.165 15.282 0.950 D3 8.242 5.415 0.700 D4 0.902 16.659 13.140 D5 16.479 5.290 17.788 D6 6.906 5.164 0.900

[0194] [Table 12]

[0195] Group Range Focal length G1 1-7 72.151 G2 8-14 -13.097 G3 15-19 70.395 G4 20-24 36.378 G5 25-27 -33.191 G6 28-32 24.534 G7 33-34 -36.625 CG 35-36 ∞

[0196] [Example 4]

[0197] (1) Optical configuration of variable magnification optical system

[0198] Figure 13 is a lens sectional view of the variable magnification optical system of Example 4. The variable magnification optical system is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. An aperture stop S is disposed on the object side of the third lens group G3, and a cover glass CG and an image plane IP are disposed on the image side of the sixth lens group G6. In the variable magnification optical system of this example, the fourth lens group G4 is the negative lens group N of the present application, and the fifth lens group G5 is the positive lens group P of the present application, which are disposed adjacent to each other in order from the object side.

[0199] In this variable magnification optical system, as shown in Figure 13 , when zooming from the wide angle end to the telephoto end, the first lens group, the third lens group, and the sixth lens group are fixed with respect to the image plane, the second lens group moves toward the image side, the fourth lens group G4 (negative lens group N) moves in a manner that traces a convex locus toward the image side, and the fifth lens group G5 (positive lens group P) moves toward the image side. In addition, by moving the fourth lens group G4 (negative lens group N) toward the image side along the optical axis, focusing is performed from an infinite distance object to a close distance object. The specific lens configuration of each lens group is shown by the surface data shown in Figure 13 and the following.

[0200] (2) Numerical example

[0201] Next, a numerical example in which specific numerical values of the lens are applied will be described. Table 13 shows the surface data of the lens. Table 14 shows the aspheric coefficients of each aspheric surface. Table 15 shows each element of the variable magnification optical system and the variable interval. Further, Table 16 shows the focal length of each lens group, and Table 21 shows the values of each conditional expression. Further, Figures 14-16 shows the longitudinal aberration diagram of the variable magnification optical system when focusing on an infinite object at the wide-angle end, the intermediate focus position, and the telephoto end.

[0202] [Table 13]

[0203]

[0204]

[0205] [Table 14]

[0206] Surface number k A4 A6 A8 A10 A12 13 0.0000 6.53368E-05 -1.10559E-06 1.11188E-08 -6.23239E-11 1.52230E-13 14 0.0000 5.09361E-05 -1.10899E-06 1.14786E-08 -6.61131E-11 1.66210E-13 16 0.0000 -1.77103E-05 -5.82790E-09 -4.12759E-10 2.90532E-12 -2.09262E-14 17 0.0000 1.18544E-05 1.36403E-08 -4.31129E-10 2.85791E-12 -1.81437E-14 26 0.0000 -1.37961E-05 -1.23907E-08 -1.35690E-09 1.86622E-11 -7.92373E-14 27 0.0000 2.18631E-05 -9.48217E-08 -5.21535E-11 9.93497E-12 -5.71261E-14

[0207] [Table 15]

[0208]

[0209]

[0210] [Table 16]

[0211] Group Range Focal length G1 1-7 69.540 G2 8-14 -12.541 G3 15-22 24.042 G4 23-25 -30.495 G5 26-27 23.245 G6 28-29 -36.546 CG 30-31 ∞

[0212] [Example 5]

[0213] (1) Optical configuration of variable magnification optical system

[0214] Figure 17 is a lens sectional view of the variable magnification optical system of Example 5 to which the present application pertains. The variable magnification optical system is composed of, in order from the object side, the first lens group G1 having positive refractive power, the second lens group G2 having negative refractive power, the third lens group G3 having positive refractive power, the fourth lens group G4 having negative refractive power, the fifth lens group G5 having positive refractive power, and the sixth lens group G6 having negative refractive power. An aperture stop S is disposed on the object side of the third lens group G3, and a cover glass CG and an image surface IP are disposed on the image side of the sixth lens group G6. In the variable magnification optical system of this example, the fourth lens group G4 is the negative lens group N of the present application, and the fifth lens group G5 is the positive lens group P of the present application, which are disposed adjacent to each other in order from the object side.

[0215] In the variable magnification optical system, as Figure 17As shown, when zooming from the wide angle end to the telephoto end, the 1st lens group, the 3rd lens group and the 6th lens group are fixed with respect to the image plane, the 2nd lens group moves toward the image side, the 4th lens group G4 (negative lens group N) moves in a manner that traces a convex toward the image side, and the 5th lens group G5 (positive lens group P) moves toward the image side. In addition, by moving the 4th lens group G4 (negative lens group N) toward the image side along the optical axis, focusing is performed from an infinite distance object to a close distance object. The specific lens configuration of each lens group is as follows Figure 17 and is shown by the surface data shown below.

[0216] (2) Numerical Example

[0217] Next, a numerical example regarding a specific numerical value of the lens is described. Table 17 shows the surface data of the lens. Table 18 shows the aspheric coefficients of each aspheric surface. Table 19 shows each element and variable interval of the zoom optical system. Further, Table 20 shows the focal length of each lens group, and Table 21 shows the values of each conditional expression. Further, Figures 18-20 shows the longitudinal aberration diagram of the zoom optical system at the wide angle end, at the intermediate focus position, and at the telephoto end when focusing on an infinite distance object.

[0218] [Table 17]

[0219]

[0220]

[0221]

[0222] [Table 18]

[0223] Surface number k A4 A6 A8 A10 A12 13 0.0000 1.38829E-04 -2.63244E-06 3.21670E-08 -2.20957E-10 6.84243E-13 14 0.0000 1.14369E-04 -2.56751E-06 3.12864E-08 -2.14375E-10 6.60824E-13 18 -0.2870 -1.58829E-05 -2.63122E-08 -1.57037E-10 -2.59302E-12 9.96663E-15 19 -49.1423 1.82709E-05 1.66082E-08 -5.30681E-10 1.40656E-12 1.62922E-15 26 -1.6261 2.63493E-05 8.21218E-08 -1.44544E-09 2.26101E-11 -1.35151E-13 27 -20.7320 -1.27413E-04 2.35261E-06 -2.94327E-08 2.26209E-10 -7.77410E-13

[0224] [Table 19]

[0225] Wide angle Intermediate Telephoto Focal length 9.888 48.010 186.256 Fno 1.65 2.45 3.50 Field of view 68.923 14.846 3.847 Image height 6.50 6.50 6.50 Total length 144.656 144.656 144.656 BF 5.759 5.759 5.759 D1 1.000 30.607 44.328 D2 44.524 14.917 1.196 D3 1.001 15.336 11.066 D4 21.713 8.554 16.057 D5 5.409 4.233 1.000

[0226] [Table 20]

[0227] Group Range Focal length G1 1-7 69.370 G2 8-14 -11.403 G3 15-22 22.776 G4 23-25 -27.557 G5 26-27 18.658 G6 28-29 -28.466 CG 30-31 ∞

[0228] [Table 21]

[0229] Example 1 Example 2 Example 3 Example 4 Example 5 (1) βpt / βpw 2.16 1.78 2.10 2.69 1.71 (2) TL / fw 15.72 16.32 16.46 15.02 14.78 (3) βnt / βnw 0.55 0.64 0.59 0.50 0.67 (4) β2t / β2w 10.60 10.49 9.56 11.00 10.64 (5) |f1 / f2| 5.47 5.54 5.51 5.54 6.08 (6) fn / f2 2.37 2.97 2.53 2.43 2.42 (7) |fp / f2| 1.76 1.61 1.87 1.85 1.64

[0230] Industrial Utility

[0231] According to the present application, it is possible to provide a zoom optical system and an image pickup apparatus that are small in size and have high imaging performance.

Claims

1. A variable magnification optical system characterized by comprising, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, the rear group comprising, in order from the object side, a fourth lens group having negative refractive power as a negative lens group N, a fifth lens group having positive refractive power as a positive lens group P, and a sixth lens group having negative refractive power, or a fourth lens group having positive refractive power, a fifth lens group having negative refractive power as a negative lens group N, a sixth lens group having positive refractive power as a positive lens group P, and a seventh lens group having negative refractive power, or a fourth lens group having negative refractive power as a negative lens group N, a fifth lens group having positive refractive power as a positive lens group P, a sixth lens group having negative refractive power, and a seventh lens group having positive refractive power, or only a negative lens group N and a positive lens group P, the positive lens group P being disposed adjacent to the negative lens group N on the image side of the negative lens group N, and the rear group having a fixed group fixed with respect to an image plane during variable magnification on the most image side thereof, during variable magnification from a wide-angle end to a telephoto end, the first lens group and the third lens group being fixed with respect to the image plane, the second lens group moving toward the image side, the negative lens group N and the positive lens group P moving with trajectories different from each other, the interval between the adjacent lens groups varying during variable magnification, satisfying the following conditional expressions: 1.4 ≤ βpt / βpw ≤ 4.0... (1) 7.0 ≤ TL / fw ≤ 20.0... (2) 5.0 ≤ β2t / β2w ≤ 14.0... (4) where βpt: the lateral magnification of the positive lens group P at the telephoto end βpw: the lateral magnification of the positive lens group P at the wide-angle end TL: the sum of the distance on the optical axis from the most object side surface to the most image side surface and the air converted length on the optical axis from the most image side surface to the image plane of the variable magnification optical system fw: the focal length of the variable magnification optical system at the wide-angle end β2t: the lateral magnification of the second lens group at the telephoto end β2w: the lateral magnification of the second lens group at the wide-angle end.

2. The variable magnification optical system according to claim 1, focusing is performed by moving the negative lens group N along the optical axis.

3. The variable magnification optical system according to claim 1, an aperture stop is provided adjacent to the object side or the image side of the third lens group or within the third lens group.

4. The variable magnification optical system according to claim 1, satisfying the following conditional expression: 0.3 ≤ βnt / βnw ≤ 0.8... (3) where βnt: the lateral magnification of the negative lens group N at the telephoto end βnw: the lateral magnification of the negative lens group N at the wide-angle end.

5. The variable magnification optical system according to claim 1, satisfying the following conditional expression: 4.5 ≤ |f1 / f2| ≤ 6.5... (5) where f1: the focal length of the first lens group f2: the focal length of the second lens group.

6. The variable magnification optical system according to claim 1, the following conditional expression is satisfied: 1.5 ≤ fn / f2 ≤ 3.5... (6) wherein, fn: focal length of the negative lens group N f2: focal length of the second lens group.

7. The variable magnification optical system according to claim 1, the following conditional expression is satisfied: 1.1 ≤ |fp / f2| ≤ 2.5... (7) wherein, fp: focal length of the positive lens group P f2: focal length of the second lens group.

8. An image pickup device, characterized by comprising: provided with: the variable magnification optical system according to any one of claims 1 to 7; and an image pickup element that converts an optical image formed by the variable magnification optical system into an electric signal.

Images