JP2014238549A - Variable power optical system, imaging optical device, and digital equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system capable of shortening the entire optical length, while satisfying both of reducing the weight of a focus group and having a vibration-proof function and to provide an imaging optical device including the variable power optical system and digital equipment.SOLUTION: A zoom lens ZL includes, in order from an object side, a positive first group Gr1, a negative second group Gr2, a positive third group Gr3, a positive fourth group Gr4, and a negative fifth group Gr5. The fourth group Gr4 is the focus group and the fifth group Gr5 is a vibration-proof group GrV. The zoom lens ZL satisfies conditional expressions of 4.0<|f1/f2|<6.0, 1.0<f4/f1<1.5, and 2.0<|f4/fv|<4.0, where f1, f2, and f4 are the focal lengths of the first group Gr1, the second group Gr2, and the fourth group Gr4 and fv is the focal length of the vibration-proof group GrV.

Description

  The present invention relates to a variable magnification optical system, an imaging optical device, and a digital device. For example, a compact zooming optical system suitable for an interchangeable lens digital camera that captures a subject image with an image sensor, and imaging optical that outputs the subject image captured with the zoom optical system and the image sensor as an electrical signal The present invention relates to a device and a digital device with an image input function such as a digital camera equipped with the imaging optical device.

  In recent years, the compactness of a mirrorless interchangeable lens camera in which a flip-up mirror is removed from a single-lens reflex camera has been accepted by users, and its market is expanding. Among such mirrorless lens interchangeable cameras, there are cameras that cannot use phase difference AF (autofocus), which has been mainstream in conventional single-lens reflex cameras. Such a camera uses so-called contrast AF, which performs focusing by scanning a focus group and searching for a place where the contrast is maximized.

  The problem is the weight of the focus group. In the case of phase difference AF, since the amount of movement of the focus group required for focusing can be calculated using information from the AF sensor, the focus group can be moved according to the amount. On the other hand, in contrast AF, the information obtained from the AF sensor is only the contrast value at that moment. By moving the focus group and reading the change in contrast at that moment, it searches for the place where the contrast becomes maximum. A focusing operation will be performed. Therefore, when the amount of movement of the focus group that moves before focusing is compared between the contrast AF and the phase difference AF, the former case is overwhelmingly large.

  In view of the above, in a variable power optical system that intends to support contrast AF, the weight reduction of the focus group is a major point (see, for example, Patent Documents 1 and 2).

JP 2012-14005 A JP 2012-225987 A

  In the zoom lens described in Patent Document 1, the second group is used as the focus group, which is insufficient in terms of reducing the weight of the focus group. Further, in the zoom lens described in Patent Document 2, the focus group is reduced in weight by using the fourth group consisting of a single lens having a negative power as the focus group. The focus group is arranged by dividing the second group of the type zoom lens into positive and negative. In a zoom lens including positive and negative from to the object side, the zooming action due to the change in the 1-2 group interval and the 2-3 group gap plays a major part in the zooming action of the entire optical system. However, in the configuration described in Patent Document 2, the zoom ratio in the second group to the fifth group is reduced by dividing the second group, and it is necessary to mainly bear the zoom ratio in the sixth group. For this reason, there is a problem that the total optical length at the telephoto end becomes large when a desired zoom ratio is achieved.

  Conventionally, only a relatively telephoto lens has been equipped with an anti-vibration function, but as the zoom lens increases in magnification, the use of the anti-vibration function on the zoom lens has advanced, and the flow has been drawn. In recent years, a low-magnification zoom lens is also equipped with an anti-vibration function. There are also imaging devices that perform image stabilization by moving the image sensor in a plane perpendicular to the optical axis, and the image stabilization function is becoming a semi-standard function.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable power optical system capable of reducing the overall optical length while achieving both a weight reduction of the focus group and an anti-vibration function. An imaging optical apparatus and a digital apparatus provided with

In order to achieve the above object, a zoom optical system according to a first aspect of the present invention includes, in order from the object side, a first group of positive power, a second group of negative power, a third group of positive power, and a positive power. A variable power optical system that performs zooming from the wide-angle end to the telephoto end by changing all of the group intervals on the axis.
Focusing is performed by moving the fourth group as a focus group in the optical axis direction,
Anti-vibration is performed by moving the whole or a part of the fifth group as an anti-vibration group in a direction perpendicular to the optical axis,
The following conditional expressions (1) to (3) are satisfied.
4.0 <| f1 / f2 | <6.0 (1)
1.0 <f4 / f1 <1.5 (2)
2.0 <| f4 / fv | <4.0 (3)
However,
f1: focal length of the first group,
f2: focal length of the second group,
f4: focal length of the fourth group,
fv: the focal length of the anti-vibration group,
It is.

A variable magnification optical system according to a second invention is characterized in that, in the first invention, the following conditional expression (4) is satisfied.
2.5 <f4 / f3 <4.5 (4)
However,
f3: focal length of the third group,
f4: focal length of the fourth group,
It is.

  A zoom optical system according to a third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, a stop is provided between the second group and the third group.

  A variable magnification optical system according to a fourth invention is the cemented lens according to any one of the first to third inventions, wherein the vibration proof group is formed of a single lens or a negative lens and a positive lens are cemented. It is characterized by comprising.

A variable magnification optical system according to a fifth invention is characterized in that, in any one of the first to fourth inventions, the following conditional expression (5) is satisfied.
0.1 <(R5A + R5B) / (R5A−R5B) <0.70 (5)
However,
R5A: radius of curvature of the surface arranged closest to the object side in the anti-vibration group,
R5B: radius of curvature of the surface of the image stabilization group with the concave surface facing the image side,
It is.

  A variable magnification optical system according to a sixth aspect of the present invention is the optical system according to any one of the first to fifth aspects, wherein the focus group includes a single lens or a cemented lens in which a negative lens and a positive lens are cemented. It is characterized by becoming.

A variable magnification optical system according to a seventh invention is characterized in that, in any one of the first to sixth inventions, the following conditional expression (6) is satisfied.
1.0 <(R4A + R4B) / (R4A-R4B) <1.2 (6)
However,
R4A: radius of curvature of the surface closest to the object in the fourth group,
R4B: radius of curvature of the surface closest to the image side in the fourth group,
It is.

  An imaging optical device according to an eighth aspect of the present invention is a zoom optical system according to any one of the first to seventh aspects of the present invention, an imaging element that converts an optical image formed on the light receiving surface into an electrical signal, and , And the zooming optical system is provided so that an optical image of a subject is formed on the light receiving surface of the image sensor.

  According to a ninth aspect of the present invention, there is provided a digital apparatus including the imaging optical device according to the eighth aspect, to which at least one function of still image shooting and moving image shooting of a subject is added.

  According to the present invention, it is possible to realize a variable power optical system and an imaging optical device that can reduce the total optical length while achieving both the weight reduction of the focus group and the image stabilization function. By using the variable magnification optical system or the imaging optical device for a digital device (for example, a digital camera), a high-performance image input function can be added to the digital device in a compact manner.

The optical block diagram of 1st Embodiment (Example 1). The optical block diagram of 2nd Embodiment (Example 2). The optical block diagram of 3rd Embodiment (Example 3). The optical block diagram of 4th Embodiment (Example 4). FIG. 3 is a longitudinal aberration diagram of Example 1. FIG. 6 is a longitudinal aberration diagram of Example 2. FIG. 6 is a longitudinal aberration diagram of Example 3. FIG. 6 is a longitudinal aberration diagram of Example 4. FIG. 3 is a lateral aberration diagram at the wide-angle end according to Example 1. FIG. 6 is a lateral aberration diagram in the intermediate focal length state according to Example 1. FIG. 3 is a lateral aberration diagram at the telephoto end according to Example 1. FIG. 6 is a lateral aberration diagram at the wide-angle end according to Example 2. FIG. 6 is a lateral aberration diagram in the intermediate focal length state according to Example 2. FIG. 6 is a lateral aberration diagram at the telephoto end according to Example 2. FIG. 12 is a lateral aberration diagram at the wide-angle end according to Example 3. FIG. 6 is a lateral aberration diagram in the intermediate focal length state according to Example 3. FIG. 12 is a lateral aberration diagram at the telephoto end according to Example 3. FIG. 6 is a lateral aberration diagram at the wide-angle end according to Example 4. FIG. 12 is a lateral aberration diagram in the intermediate focal length state according to Example 4. FIG. 12 is a lateral aberration diagram at the telephoto end according to Example 4. The schematic diagram which shows the example of schematic structure of the digital apparatus carrying a variable magnification optical system.

  Hereinafter, a variable magnification optical system, an imaging optical device, and a digital apparatus according to the present invention will be described. The zoom optical system according to the present invention includes, in order from the object side, a first group of positive power, a second group of negative power, a third group of positive power, a fourth group of positive power, and a negative power A variable power optical system having a fifth lens group (power: an amount defined by the reciprocal of the focal length), and performing variable power from the wide-angle end to the telephoto end by changing all the group intervals on the axis The focusing is performed by moving the fourth group as the focus group in the optical axis direction, and the whole or a part of the fifth group is moved as the anti-vibration group in the direction perpendicular to the optical axis. It is configured to perform shaking (that is, camera shake correction).

  By adopting the configuration including positive / negative / positive / positive in order from the object side as described above, it becomes possible to bear the main ratio of the variable magnification burden by changing the group interval between the first and second groups and the second and third groups. This is an advantageous configuration in terms of the overall optical length. By performing the focusing in the fourth group, the group responsible for focus and the group responsible for zooming are divided, so that excellent focusing can be realized in each zooming state. In addition, since the anti-vibration group is arranged in the fifth group, it becomes possible to perform anti-vibration behind the fourth group which is the focus group, and therefore the axis to the anti-vibration group in each focusing state ranging from infinity to proximity. The incident position difference of the external light beam can be reduced. Therefore, there is an advantage that good vibration isolation becomes possible.

In order to achieve high performance in the above configuration, it is desirable that the following conditional expressions (1) to (3) are satisfied.
4.0 <| f1 / f2 | <6.0 (1)
1.0 <f4 / f1 <1.5 (2)
2.0 <| f4 / fv | <4.0 (3)
However,
f1: focal length of the first group,
f2: focal length of the second group,
f4: focal length of the fourth group,
fv: the focal length of the anti-vibration group,
It is.

  Conditional expression (1) defines the focal length ratio between the first group and the second group. If the lower limit of conditional expression (1) is surpassed, the power of the first group becomes too large, and the variable magnification load between the first and second groups becomes large, so that coma in the negative direction increases. If the upper limit of conditional expression (1) is exceeded, the power of the second group becomes too large and the zooming load between the second and third groups becomes large, so that coma in the positive direction becomes significant. Therefore, satisfying the conditional expression (1) makes it possible to achieve high performance at the time of zooming in a balanced manner.

  Conditional expression (2) defines the focal length ratio between the fourth group and the first group. If the lower limit of conditional expression (2) is not reached, the power of the fourth group becomes too large, and astigmatism and coma change will become noticeable during focusing. If the upper limit of conditional expression (2) is exceeded, the power of the fourth group becomes too small and the amount of movement of the fourth group at the time of focusing increases (especially at the telephoto end). Fluctuation increases. Therefore, satisfying conditional expression (2) makes it possible to achieve high performance during focusing in a well-balanced manner.

  Conditional expression (3) defines the focal length ratio between the image stabilizing group and the fourth group. If the lower limit of conditional expression (3) is not reached, the power of the image stabilization group becomes too small, the amount of eccentricity of the image stabilization group required for image stabilization increases, and the lateral chromatic aberration variation increases. If the upper limit of the conditional expression (3) is exceeded, the power of the image stabilization group becomes too large, and the coma aberration fluctuation during image stabilization becomes large. Therefore, satisfying conditional expression (3) makes it possible to achieve high performance during vibration isolation in a well-balanced manner.

  According to the above characteristic configuration, it is possible to realize a variable magnification optical system and an imaging optical device that can reduce the total optical length while achieving both a weight reduction of the focus group and an image stabilization function. If a miniaturized variable magnification optical system or imaging optical device having the image stabilization function is used in a digital device such as a digital camera, it becomes possible to add a high-performance image input function to the digital device in a compact manner. It can contribute to the downsizing, cost reduction, high performance and high functionality of digital equipment. For example, since the variable power optical system according to the present invention is suitable as an interchangeable lens for a mirrorless type interchangeable lens digital camera, it is possible to realize a lightweight and compact interchangeable lens that is convenient to carry. The conditions for achieving such effects in a well-balanced manner and achieving higher optical performance, downsizing, etc. will be described below.

It is desirable to satisfy the following conditional expression (4).
2.5 <f4 / f3 <4.5 (4)
However,
f3: focal length of the third group,
f4: focal length of the fourth group,
It is.

  Conditional expression (4) defines the focal length ratio between the third group and the fourth group. If the lower limit of conditional expression (4) is not reached, the power of the third group becomes too small, and the scaling burden at the second to third group intervals decreases, and the scaling burden of the fourth group increases. It is difficult to achieve good performance over the entire focusing area. If the upper limit of conditional expression (4) is exceeded, the power of the third group becomes too large, the burden at the intervals of the second and third groups becomes large at the time of zooming, and the coma aberration variation becomes large. Therefore, by satisfying conditional expression (4), it is possible to achieve a high performance at the time of zooming and focusing in a balanced manner.

  It is desirable to have a stop between the second group and the third group. By disposing the diaphragm between the second group and the third group, it becomes possible to correct astigmatism and coma occurring in the second group in the third and subsequent groups, and the entire zooming region. Astigmatism and coma can be satisfactorily corrected. Therefore, it is preferable to set the stop position in the variable magnification optical system between two or three groups.

  It is desirable that the image stabilizing group is composed of a single lens or a cemented lens in which a negative lens and a positive lens are cemented. In this way, by limiting the number of components of the anti-vibration group, it is possible to reduce the weight of the anti-vibration group, and thus it is possible to reduce the members necessary for driving the anti-vibration group. Therefore, it is advantageous for reducing the size of the optical system.

It is desirable to satisfy the following conditional expression (5).
0.1 <(R5A + R5B) / (R5A−R5B) <0.70 (5)
However,
R5A: radius of curvature of the surface arranged closest to the object side in the anti-vibration group,
R5B: radius of curvature of the surface of the image stabilization group with the concave surface facing the image side,
It is.

  It is desirable that the most object-side surface of the vibration isolation group has a concave surface facing the object side. Further, it is desirable that the image stabilizing group has at least one lens surface with the concave surface facing the image surface side. By adopting such a configuration, it is possible to suppress fluctuations in coma aberration during image stabilization, and it is possible to realize good image stabilization performance. Conditional expression (5) specifically defines the lens surface shape of the image stabilizing group. If the conditional expression (5) is outside the conditional expression range, it will be difficult to suppress fluctuations in coma aberration that occur during image stabilization, and performance degradation during image stabilization will become significant. For example, if the lower limit of the conditional expression (5) is not reached, the coma aberration greatly fluctuates in the plus direction during image stabilization, and if the upper limit of the conditional expression (5) is exceeded, the coma aberration fluctuates in the minus direction during image stabilization. Therefore, satisfying the conditional expression (5) makes it possible to achieve high performance during vibration isolation in a well-balanced manner.

  It is desirable that the focus group is composed of a single lens or a cemented lens in which a negative lens and a positive lens are cemented. In this way, by limiting the number of components of the focus group, the weight of the focus group can be reduced, and a configuration suitable for contrast AF can be achieved.

It is desirable to satisfy the following conditional expression (6).
1.0 <(R4A + R4B) / (R4A-R4B) <1.2 (6)
However,
R4A: radius of curvature of the surface closest to the object in the fourth group,
R4B: radius of curvature of the surface closest to the image side in the fourth group,
It is.

  The fourth group, which is the focus group, preferably has a meniscus shape with a concave surface facing the object side. By using a positive meniscus lens having a concave surface on the object side as a focus group, fluctuations in coma and astigmatism due to focus can be suppressed. Conditional expression (6) specifically defines the lens surface shape of the focus group. If the upper limit of conditional expression (6) is exceeded, the power of the focus group becomes too small, and the amount of movement of the focus group becomes large especially during focusing in the telephoto state. growing. If the lower limit of conditional expression (6) is not reached, the power of the image side surface of the focus group increases, and astigmatism and coma change due to the change of the incident position of the off-axis light beam due to focusing increase. Therefore, satisfying conditional expression (6) makes it possible to achieve high performance during focusing with a good balance.

  The zoom optical system according to the present invention is suitable for use as an imaging lens for a digital device with an image input function (for example, a digital camera). By combining this with an imaging device or the like, an image of a subject is optically displayed. It is possible to configure an image pickup optical device that takes in and outputs as an electrical signal. The imaging optical device is an optical device that constitutes a main component of a camera used for still image shooting and moving image shooting of a subject. For example, a variable power optical system that forms an optical image of an object in order from the object (that is, subject) side. (For example, a zoom lens) and an image sensor that converts an optical image formed by the zoom optical system into an electrical signal. In addition, the variable magnification optical system having the above-described characteristic configuration is arranged so that the optical image of the subject is formed on the light receiving surface (that is, the imaging surface) of the image sensor, thereby achieving high performance at a small size and low cost. It is possible to realize an imaging optical device having the above and a digital device including the same.

  Examples of digital devices with an image input function include cameras such as digital cameras, video cameras, surveillance cameras, in-vehicle cameras, and videophone cameras. It can also be built in or externally attached to personal computers, portable digital devices (for example, mobile phones, smart phones (high performance mobile phones), mobile computers, etc.), peripheral devices (scanners, printers, etc.), and other digital devices. One with a camera function can be mentioned. As can be seen from these examples, it is possible not only to configure a camera by using an imaging optical device, but also to add a camera function by mounting the imaging optical device on various devices. For example, a digital device with an image input function such as a mobile phone with a camera can be configured.

  FIG. 21 is a schematic cross-sectional view showing a schematic configuration example of a digital device DU as an example of a digital device with an image input function. The imaging optical device LU mounted in the digital device DU shown in FIG. 21 sequentially forms an optical image (image plane) IM of the object so as to be variable in order from the object (namely, subject) side. Axis), a plane parallel plate PT (cover glass of the image sensor SR; corresponding to an optical filter such as an optical low-pass filter and an infrared cut filter arranged as necessary), and a light receiving surface by a zoom lens ZL (Imaging surface) An imaging element SR that converts an optical image IM formed on the SS into an electrical signal is provided. When a digital device DU with an image input function is constituted by this imaging optical device LU, the imaging optical device LU is usually arranged inside the body, but when necessary to realize the camera function, a form as necessary is adopted. Is possible. For example, the unitized imaging optical device LU can be configured to be detachable or rotatable with respect to the main body of the digital device DU.

  The zoom lens ZL has five groups of positive, negative, positive, positive and negative, and is a variable power optical system that performs zooming from the wide angle end to the telephoto end by changing all the group distances on each axis. Focusing is performed by moving the fourth group as a focus group in the direction of the optical axis AX, and the whole or a part of the fifth group is set as a vibration-proofing group so that vibration is prevented by moving in the direction perpendicular to the optical axis AX. It has become. As the image sensor SR, for example, a solid-state image sensor such as a CCD (Charge Coupled Device) type image sensor having a plurality of pixels or a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor is used. Since the zoom lens ZL is provided so that the optical image IM of the subject is formed on the light receiving surface SS which is a photoelectric conversion unit of the image sensor SR, the optical image IM formed by the zoom lens ZL is the image sensor. It is converted into an electric signal by SR.

  The digital device DU includes a signal processing unit 1, a control unit 2, a memory 3, an operation unit 4, a display unit 5 and the like in addition to the imaging optical device LU. The signal generated by the image sensor SR is subjected to predetermined digital image processing, image compression processing, and the like in the signal processing unit 1 as necessary, and recorded as a digital video signal in the memory 3 (semiconductor memory, optical disc, etc.) In some cases, it is transmitted to other devices via a cable or converted into an infrared signal or the like (for example, a communication function of a mobile phone). The control unit 2 is composed of a microcomputer and controls functions such as shooting functions (still image shooting function, moving image shooting function, etc.) and image reproduction functions; control of a lens moving mechanism for zooming, focusing, camera shake correction, etc. Do it intensively. For example, the control unit 2 controls the imaging optical device LU so as to perform at least one of still image shooting and moving image shooting of a subject. The display unit 5 includes a display such as a liquid crystal monitor, and performs image display using an image signal converted by the image sensor SR or image information recorded in the memory 3. The operation unit 4 is a part including operation members such as an operation button (for example, a release button) and an operation dial (for example, a shooting mode dial), and transmits information input by the operator to the control unit 2.

  Here, the specific optical configuration of the zoom lens ZL will be described in more detail with reference to the first to fourth embodiments. FIGS. 1 to 4 are optical configuration diagrams respectively corresponding to the zoom lenses ZL constituting the first to fourth embodiments. The wide-angle end (W), the intermediate focal length state (M), and the telephoto end (T The lens arrangement, lens shape, etc. are shown in the optical section. In the first to fourth embodiments (FIGS. 1 to 4), in order from the object side, the first group Gr1 having positive power, the second group Gr2 having negative power, and the third group having positive power. Gr3, a fourth group Gr4 having a positive power, and a fifth group Gr5 having a negative power, and by changing all the group intervals on the axis, the wide-angle end (W) to the telephoto end (T) It is configured to perform zooming (that is, zooming).

  At the time of zooming, the first group Gr1, the second group Gr2, the third group Gr3, the fourth group Gr4, and the fifth group Gr5 move relative to the image plane IM, respectively. The aperture stop ST is located on the object side of the third group Gr3, and moves together with the third group Gr3 during zooming. At the time of focusing, the fourth group Gr4 moves along the optical axis AX. That is, the fourth group Gr4 is a focus group, and moves to the object side during focusing on a short-distance object as indicated by an arrow mF. The entire fifth group Gr5 or the sub group including the lens closest to the object side in the fifth group Gr5 is the image stabilization group GrV. As shown by the arrow mV, the image stabilization is performed by moving perpendicularly to the optical axis AX. Is done.

  The first embodiment (FIG. 1) of the zoom lens ZL has a zoom configuration in which the first group Gr1 to the fifth group Gr5 are movable and the sixth group Gr6 is fixed at the time of zooming in six groups of positive, negative, positive, positive and negative. ing. The fourth group Gr4 acts as a focus group, and the fifth group Gr5 acts as a vibration isolation group. In zooming from the wide-angle end (W) to the telephoto end (T), the first group Gr1 monotonously moves toward the object side, the second group Gr2 monotonically moves toward the image side, and the third group Gr3 moves toward the object side. The fourth group Gr4 once moves to the object side and then makes a U-turn to the image side, and the fifth group Gr5 moves to the object side monotonously.

  The second embodiment (FIG. 2) of the zoom lens ZL has a zoom configuration in which the first group Gr1 to the fifth group Gr5 are movable during zooming in five groups of positive, negative, positive and negative. The fourth group Gr4 functions as a focus group, and the most object side lens in the fifth group Gr5 functions as a vibration-proof group. In zooming from the wide-angle end (W) to the telephoto end (T), the first group Gr1 monotonously moves toward the object side, the second group Gr2 monotonically moves toward the image side, and the third group Gr3 moves toward the object side. The fourth group Gr4 once moves to the object side and then makes a U-turn to the image side, and the fifth group Gr5 once moves to the object side and then makes a U-turn to the image side.

  The third embodiment (FIG. 3) of the zoom lens ZL has a zoom configuration in which the first group Gr1 to the fifth group Gr5 are movable during zooming in five groups of positive, negative, positive and negative. The fourth group Gr4 acts as a focus group, and the cemented lens closest to the object in the fifth group Gr5 acts as a vibration-proof group. In zooming from the wide-angle end (W) to the telephoto end (T), the first group Gr1 monotonously moves toward the object side, the second group Gr2 monotonically moves toward the image side, and the third group Gr3 moves toward the object side. The fourth group Gr4 once moves to the object side and then makes a U-turn to the image side, and the fifth group Gr5 once moves to the object side and then makes a U-turn to the image side.

  The fourth embodiment (FIG. 4) of the zoom lens ZL has a zoom configuration in which the first group Gr1 to the fifth group Gr5 are movable during zooming in five groups of positive, negative, positive and negative. The fourth group Gr4 acts as a focus group, and the cemented lens closest to the object in the fifth group Gr5 acts as a vibration-proof group. In zooming from the wide-angle end (W) to the telephoto end (T), the first group Gr1 monotonously moves toward the object side, the second group Gr2 monotonically moves toward the image side, and the third group Gr3 moves toward the object side. The fourth group Gr4 once moves to the object side and then makes a U-turn to the image side, and the fifth group Gr5 once moves to the object side and then makes a U-turn to the image side.

  Each group in the first embodiment (FIG. 1) is configured as follows in order from the object side when each lens is viewed with a paraxial surface shape. The first group Gr1 includes a cemented lens including a negative meniscus lens concave on the image side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. The second group Gr2 includes a negative meniscus lens concave on the image side, a biconcave negative lens, a biconvex positive lens, and a negative meniscus lens concave on the object side. The third lens unit Gr3 includes a biconvex positive lens composed of a double-sided aspheric surface, and a cemented lens composed of a biconcave negative lens and a biconvex positive lens. ST is arranged. The fourth group Gr4 is composed of a single positive meniscus lens convex on the image side made of double-sided aspherical surfaces. The fifth group Gr5 is composed of one biconcave negative lens (anti-vibration group GrV). The sixth group Gr6 is composed of one biconvex positive lens.

  Each group in the second embodiment (FIG. 2) is configured as follows in order from the object side when each lens is viewed with a paraxial surface shape. The first group Gr1 includes a cemented lens including a negative meniscus lens concave on the image side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. The second group Gr2 includes two biconcave negative lenses and a cemented lens including a biconvex positive lens and a biconcave negative lens. The third lens unit Gr3 includes a biconvex positive lens composed of a double-sided aspheric surface, and a cemented lens composed of a biconcave negative lens and a biconvex positive lens. ST is arranged. The fourth group Gr4 is composed of a single positive meniscus lens convex on the image side made of double-sided aspherical surfaces. The fifth group Gr5 includes a biconcave negative lens (anti-vibration group GrV) and a biconvex positive lens.

  Each group in the third embodiment (FIG. 3) is configured as follows in order from the object side when each lens is viewed with a paraxial surface shape. The first group Gr1 includes a cemented lens including a negative meniscus lens concave on the image side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. The second group Gr2 includes two biconcave negative lenses and a biconvex positive lens. The third lens unit Gr3 includes a biconvex positive lens composed of a double-sided aspheric surface, and a cemented lens composed of a biconcave negative lens and a biconvex positive lens. ST is arranged. The fourth group Gr4 is composed of a single positive meniscus lens convex on the image side made of double-sided aspherical surfaces. The fifth group Gr5 includes a biconcave negative lens, a cemented lens (anti-vibration group GrV) including a positive meniscus lens convex on the object side, and a biconvex positive lens.

  Each group in the fourth embodiment (FIG. 4) is configured as follows in order from the object side when each lens is viewed with a paraxial surface shape. The first group Gr1 includes a cemented lens including a negative meniscus lens concave on the image side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. The second group Gr2 includes two biconcave negative lenses and a biconvex positive lens. The third lens unit Gr3 includes a biconvex positive lens composed of a double-sided aspheric surface, and a cemented lens composed of a biconcave negative lens and a biconvex positive lens. ST is arranged. The fourth group Gr4 includes a cemented lens including a biconvex positive lens whose object side surface is an aspheric surface and a negative meniscus lens concave on the object side whose image side surface is an aspheric surface. The fifth group Gr5 includes a cemented lens (anti-vibration group GrV) including a biconcave negative lens and a negative meniscus lens concave on the image side, and a biconvex positive lens.

  Hereinafter, the configuration and the like of the zoom optical system embodying the present invention will be described more specifically with reference to the construction data of the examples. Examples 1 to 4 (EX1 to 4) listed here are numerical examples corresponding to the first to fourth embodiments, respectively, and are optical configuration diagrams showing the first to fourth embodiments. (FIGS. 1 to 4) show the lens arrangement, lens shape, and the like of the corresponding first to fourth embodiments.

In the construction data of each embodiment, as surface data, in order from the left column, the surface number, the radius of curvature r (mm), the axial upper surface distance d (mm), and the refractive indexes nd and d regarding the d-line (wavelength 587.56 nm) The Abbe number vd for the line is shown. A surface with * in the surface number is an aspheric surface, and the surface shape is defined by the following expression (AS) using a local orthogonal coordinate system (x, y, z) with the surface vertex as the origin. . As aspheric data, an aspheric coefficient or the like is shown. It should be noted that the coefficient of the term not described in the aspherical data of each example is 0, and E−n = × 10 ⁻ⁿ for all data.
z = (c · h ² ) / [1 + √ {1− (1 + K) · c ² · h ² }] + Σ (Aj · h ^j ) (AS)
However,
h: height in the direction perpendicular to the z axis (optical axis AX) (h ² = x ² + y ² ),
z: the amount of sag in the direction of the optical axis AX at the position of the height h (based on the surface vertex),
c: curvature at the surface vertex (the reciprocal of the radius of curvature r),
K: conic constant,
Aj: j-order aspheric coefficient,
It is.

  As various data, the zoom ratio (magnification ratio) is shown, and for each focal length state W, M, T, the focal length (f, mm), F number (FNO), half angle of view (ω, °) of the entire system. ), Image height (Y ′, mm), total lens length (TL, mm), back focus (BF, mm), and variable surface distance di (i: surface number, mm). The focal lengths (f1, f2, f3, f4, f5, f6; mm) of the lens group are shown. However, the back focus BF used here is the distance from the image side surface of the plane parallel plate PT to the image plane IM, and the total lens length TL is the distance from the lens front surface to the image plane IM. Table 1 shows data related to the conditional expression for each example, and Table 2 shows values corresponding to the conditional expression for each example.

  FIGS. 5 to 8 are longitudinal aberration diagrams (normal (before decentering), infinite focus state) corresponding to Examples 1 to 4 (EX1 to EX4), respectively (A) to (C). : Wide angle end (W), (D) to (F): Intermediate focal length state (M), (G) to (I): Various aberrations at the telephoto end (T). 5-8, (A), (D), (G) are spherical aberration diagrams, (B), (E), (H) are astigmatism diagrams, (C), (F), (I). ) Is a distortion diagram. The spherical aberration diagram shows the amount of spherical aberration with respect to the d-line (wavelength 587.56 nm) indicated by the solid line, the amount of spherical aberration with respect to the C-line (wavelength 656.28 nm) indicated by the alternate long and short dash line, and the g-line (wavelength 435.84 nm) indicated by the broken line. The amount of spherical aberration is represented by the amount of deviation (unit: mm) in the optical axis AX direction from the paraxial image plane, and the vertical axis is a value obtained by normalizing the height of incidence on the pupil by its maximum height (ie, (Relative pupil height). In the astigmatism diagram, the broken line T represents the tangential image surface with respect to the d line, and the solid line S represents the sagittal image surface with respect to the d line, expressed as a deviation amount (unit: mm) in the optical axis AX direction from the paraxial image surface. The vertical axis represents the image height (IMG HT, unit: mm). In the distortion diagrams, the horizontal axis represents distortion (unit:%) with respect to the d-line, and the vertical axis represents image height (IMG HT, unit: mm). Note that the maximum value of the image height IMG HT corresponds to half the diagonal length of the light receiving surface SS of the image sensor SR.

  FIGS. 9 to 11, 12 to 14, 15 to 17, and 18 to 20 are lateral aberration diagrams corresponding to Examples 1 to 4 (EX 1 to EX 4), respectively. The lateral aberration (mm) at normal time (before decentration) in states W, M, and T is shown. In each of FIGS. 9 to 20, (A) to (C) show transverse aberration with a tangential beam, and (D) to (F) show transverse aberration with a sagittal beam. In addition, the lateral aberration at the image height ratio (half angle of view ω °) represented by RELATIVE FIELD HEIGHT indicates the d line (wavelength 587.56 nm) indicated by a solid line, and the C line (wavelength 656.28 nm) indicated by a one-dot chain line. , The g-line (wavelength 435.84 nm) indicated by a broken line. The image height ratio is a relative image height obtained by normalizing the image height with the maximum image height Y ′.

Example 1
Unit: mm
Surface data Surface number rd nd vd
1 53.353 1.200 1.8467 23.78
2 34.674 6.416 1.4970 81.61
3 402.870 0.100
4 38.442 4.236 1.6968 55.46
5 191.178 d5
6 312.305 0.800 1.9108 35.25
7 11.384 4.798
8 -33.732 0.800 1.7725 49.62
9 34.947 0.100
10 21.959 3.793 1.8467 23.78
11 -24.154 0.854
12 -18.083 0.800 1.8348 42.72
13 -130.439 d13
14 (Aperture) ∞ 0.100
15 * 15.000 2.454 1.7308 40.50
16 * -64.765 3.097
17 -97.252 0.800 1.9037 31.31
18 11.577 4.360 1.4970 81.61
19 -12.667 d19
20 * -968.683 3.846 1.5831 59.38
21 * -35.765 d21
22 -66.082 0.800 1.8348 42.72
23 22.247 d23
24 35.757 2.171 1.6727 32.17
25 -658.266 13.500
26 ∞ 4.200 1.5168 64.20
27 ∞ BF

Aspheric data
K A4 A6 A8
15th surface 0.00000 7.4222E-06 -9.8313E-09 1.9918E-09
16th surface 0.00000 8.6528E-05 -1.1015E-08 -1.3227E-10
20th surface 0.00000 -1.1988E-04 -9.3860E-07 0.0000E + 00
21st surface 0.00000 -1.2049E-04 -6.4789E-07 0.0000E + 00

Various data Zoom ratio 6.95
Wide angle (W) Medium (M) Telephoto (T)
Focal length 14.260 37.580 99.050
F number 3.500 5.000 5.600
Half angle of view (degrees) 37.186 16.056 6.231
Image height 9.717 11.198 11.406
Total lens length 94.980 98.931 109.980
BF 1.050 1.050 1.050
d5 2.000 14.277 26.978
d13 23.992 8.813 2.000
d19 2.489 3.893 13.003
d21 2.594 7.308 2.000
d23 3.630 4.364 5.723

Zoom lens group data Group Start surface Focal length
1 1 53.023
2 6 -10.787
3 15 19.161
4 20 63.589
5 22 -19.855
6 24 50.479

Example 2
Unit: mm
Surface data Surface number rd nd vd
1 45.466 1.200 1.8467 23.78
2 31.613 5.943 1.4970 81.61
3 250.961 0.100
4 44.010 3.874 1.6968 55.46
5 226.794 d5
6 -851.489 0.800 1.9108 35.25
7 10.873 4.711
8 -35.933 0.800 1.8042 46.50
9 443.298 0.166
10 20.941 2.943 1.9229 20.88
11 -82.200 0.800 1.8348 42.72
12 37.313 d12
13 (Aperture) ∞ 0.100
14 * 16.355 4.031 1.7308 40.50
15 * -24.902 2.084
16 -24.142 1.883 1.9037 31.31
17 13.821 6.282 1.4970 81.61
18 -11.790 d18
19 * -802.917 4.200 1.5891 61.25
20 * -35.420 d20
21 -86.192 0.800 1.8348 42.72
22 21.050 3.674
23 44.976 2.646 1.6730 38.15
24 -88.794 d24
25 ∞ 4.200 1.5168 64.20
26 ∞ BF

Aspheric data
K A4 A6 A8
14th surface 0.00000 -5.4651E-06 1.0123E-07 9.6859E-09
15th surface 0.00000 8.2055E-05 1.3694E-07 9.7214E-09
19th surface 0.00000 -1.1413E-04 -7.1734E-07 0.0000E + 00
20th surface 0.00000 -1.1072E-04 -4.8996E-07 0.0000E + 00

Various data Zoom ratio 6.95
Wide angle (W) Medium (M) Telephoto (T)
Focal length 14.260 37.590 99.060
F number 3.600 5.000 5.500
Half angle of view (degrees) 37.182 16.053 6.231
Statue height 9.721 11.319 11.684
Total lens length 99.643 102.280 113.387
BF 1.050 1.050 1.050
d5 2.249 14.243 28.562
d12 26.227 8.973 2.081
d18 2.373 4.308 14.711
d20 2.805 8.179 2.115
d24 13.702 14.289 13.631

Zoom lens group data Group Start surface Focal length
1 1 55.083
2 6 -11.414
3 14 20.822
4 19 62.771
5 21 -44.660

Example 3
Unit: mm
Surface data Surface number rd nd vd
1 55.637 1.200 1.8467 23.78
2 35.997 5.169 1.4970 81.61
3 688.516 0.100
4 41.080 4.006 1.6968 55.46
5 195.320 d5
6 -454.535 0.800 1.9108 35.25
7 10.583 4.625
8 -30.504 0.800 1.8810 40.14
9 29.951 0.100
10 22.006 2.919 1.9229 20.88
11 -61.375 d11
12 (Aperture) ∞ 0.100
13 * 15.660 4.639 1.7308 40.50
14 * -48.995 2.624
15 -48.941 0.800 1.9037 31.31
16 12.525 7.782 1.4970 81.61
17 -12.999 d17
18 * -940.006 4.200 1.5831 59.46
19 * -36.781 d19
20 -54.041 0.800 1.8830 40.80
21 22.058 1.000 1.4970 81.61
22 23.898 1.948
23 29.826 2.894 1.6541 39.68
24 -131.437 d24
25 ∞ 4.200 1.5168 64.20
26 ∞ BF

Aspheric data
K A4 A6 A8
13th surface 0.00000 1.6992E-05 1.5202E-07 1.0224E-08
14th surface 0.00000 9.3824E-05 3.0875E-07 1.2966E-08
18th surface 0.00000 -1.0940E-04 -6.1173E-07 0.0000E + 00
19th surface 0.00000 -1.0586E-04 -4.3117E-07 0.0000E + 00

Various data Zoom ratio 6.95
Wide angle (W) Medium (M) Telephoto (T)
Focal length 14.260 37.580 99.050
F number 3.600 5.000 5.500
Half angle of view (degrees) 37.185 16.056 6.231
Image height 9.720 11.078 11.484
Total lens length 99.980 103.937 113.974
BF 1.050 1.050 1.050
d5 2.301 13.711 30.225
d11 26.501 8.831 2.045
d17 2.392 3.802 14.447
d19 3.530 8.133 2.000
d24 13.500 17.703 13.500

Zoom lens group data Group Start surface Focal length
1 1 55.323
2 6 -11.763
3 13 21.854
4 18 65.531
5 20 -40.815

Example 4
Unit: mm
Surface data Surface number rd nd vd
1 55.068 1.200 1.8467 23.78
2 35.333 5.320 1.4970 81.61
3 482.141 0.100
4 39.209 4.129 1.6968 55.46
5 183.047 d5
6 -6788.303 0.800 1.8830 40.80
7 10.292 4.753
8 -34.335 0.800 1.8830 40.80
9 32.325 0.100
10 21.895 2.847 1.9229 20.88
11 -104.275 d11
12 (Aperture) ∞ 0.100
13 * 15.819 4.124 1.7308 40.50
14 * -50.999 2.696
15 -38.375 0.800 1.9037 31.31
16 13.826 6.345 1.4970 81.61
17 -12.402 d17
18 * 224 178.550 4.200 1.5831 59.46
19 -33.203 2.000 1.8820 37.22
20 * -34.848 d20
21 -45.157 0.800 1.8830 40.80
22 24.457 0.963 1.4970 81.61
23 23.855 1.604
24 28.021 3.034 1.6541 39.68
25 -101.530 d25
26 ∞ 4.200 1.5168 64.20
27 ∞ BF

Aspheric data
K A4 A6 A8
13th surface 0.00000 2.0212E-05 4.4038E-07 1.2928E-08
14th surface 0.00000 9.6020E-05 7.0304E-07 1.6560E-08
18th surface 0.00000 -8.8546E-05 2.7168E-08 0.0000E + 00
20th surface 0.00000 -5.0144E-05 0.0000E + 00 0.0000E + 00

Various data Zoom ratio 6.95
Wide angle (W) Medium (M) Telephoto (T)
Focal length 14.260 37.580 99.060
F number 3.600 5.000 5.500
Half angle of view (degrees) 37.184 16.054 6.231
Statue height 9.729 11.008 11.383
Total lens length 99.980 104.333 113.986
BF 1.050 1.050 1.050
d5 2.178 13.391 29.559
d11 26.288 9.032 2.379
d17 2.387 4.195 14.395
d20 3.661 8.061 2.000
d25 13.500 17.688 13.688

Zoom lens group data Group Start surface Focal length
1 1 55.323
2 6 -11.763
3 13 21.854
4 18 65.531
5 21 -40.815

DU Digital equipment LU Imaging optical device ZL Zoom lens (variable magnification optical system)
Gr1 1st group Gr2 2nd group Gr3 3rd group Gr4 4th group Gr5 5th group Gr6 6th group GrV Anti-vibration group ST Aperture (aperture stop)
SR Image sensor SS Photosensitive surface (imaging surface)
IM image plane (optical image)
AX Optical axis 1 Signal processing unit 2 Control unit 3 Memory 4 Operation unit 5 Display unit

Claims (9)

In order from the object side, there are a first group of positive power, a second group of negative power, a third group of positive power, a fourth group of positive power, and a fifth group of negative power. A variable magnification optical system that performs variable magnification from the wide-angle end to the telephoto end by changing all of the above-mentioned group intervals,
Focusing is performed by moving the fourth group as a focus group in the optical axis direction,
Anti-vibration is performed by moving the whole or a part of the fifth group as an anti-vibration group in a direction perpendicular to the optical axis,
A variable magnification optical system characterized by satisfying the following conditional expressions (1) to (3);
4.0 <| f1 / f2 | <6.0 (1)
1.0 <f4 / f1 <1.5 (2)
2.0 <| f4 / fv | <4.0 (3)
However,
f1: focal length of the first group,
f2: focal length of the second group,
f4: focal length of the fourth group,
fv: the focal length of the anti-vibration group,
It is. The zoom lens system according to claim 1, wherein the following conditional expression (4) is satisfied:
2.5 <f4 / f3 <4.5 (4)
However,
f3: focal length of the third group,
f4: focal length of the fourth group,
It is.   3. The variable magnification optical system according to claim 1, further comprising a stop between the second group and the third group.   The variable power optical system according to any one of claims 1 to 3, wherein the image stabilizing group is formed of a single lens or a cemented lens in which a negative lens and a positive lens are cemented. The zoom lens system according to any one of claims 1 to 4, wherein the following conditional expression (5) is satisfied;
0.1 <(R5A + R5B) / (R5A−R5B) <0.70 (5)
However,
R5A: radius of curvature of the surface arranged closest to the object side in the anti-vibration group,
R5B: radius of curvature of the surface of the image stabilization group with the concave surface facing the image side,
It is.   The variable power optical system according to claim 1, wherein the focus group includes a single lens or a cemented lens in which a negative lens and a positive lens are cemented. The zoom lens system according to claim 1, wherein the following conditional expression (6) is satisfied:
1.0 <(R4A + R4B) / (R4A-R4B) <1.2 (6)
However,
R4A: radius of curvature of the surface closest to the object in the fourth group,
R4B: radius of curvature of the surface closest to the image side in the fourth group,
It is.   A variable magnification optical system according to any one of claims 1 to 7, and an image sensor that converts an optical image formed on the light receiving surface into an electrical signal, on the light receiving surface of the image sensor An imaging optical apparatus, wherein the zoom optical system is provided so that an optical image of a subject is formed.   9. A digital apparatus, comprising the imaging optical device according to claim 8 to which at least one function of still image shooting and moving image shooting of a subject is added.

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