JP2012022019A - Zoom lens system, exchange lens device and camera system - Google Patents

Abstract

A zoom lens system in which a focusing lens is lightweight and compact is provided.
A first lens group having a negative refractive power, a second lens group having a negative refractive power, and a succeeding group having at least one positive refractive power in order from the object side to the image plane side. And during zooming, the distance between the lens groups is changed, and during focusing from the infinite focus state to the close object focus state, the distance between the first lens group and the second lens group, The distance between the second lens group and the lens group closest to the object in the subsequent group changes, and the entire subsequent group having a positive refractive power or a part thereof is optically corrected for image blurring. A zoom lens system, an interchangeable lens apparatus, and a camera system, characterized by moving in a direction perpendicular to the optical axis.
[Selection] Figure 1

Description

  The present invention relates to a zoom lens system, an interchangeable lens device, and a camera system.

  In recent years, an interchangeable lens apparatus including a camera body having an image sensor such as a charge coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS), and a zoom lens system for forming an optical image on a light receiving surface of the image sensor. The market for interchangeable lens camera systems (hereinafter also simply referred to as “camera systems”) in which an imaging lens is detachable from a camera body is rapidly expanding. Such an interchangeable lens device is popular not only for taking a still image but also having a lens capable of taking a moving image.

  Conventionally, zoom lenses having a negative refractive power closest to the object side are often used particularly as zoom lenses for a wide angle of view because it is easy to widen the angle of view and to make the close-up shooting distance relatively short.

  Patent Document 1 discloses a zoom lens that includes four lens groups having negative, negative, positive, and positive refractive power in order from the object side, and moves a second lens group having negative refractive power during focusing.

  Patent Document 2 discloses a zoom lens that is composed of three lens groups of negative, negative, and positive refractive power in order from the object side, divides the third lens group into a front group and a rear group, and moves the front group during focusing. is doing.

  Patent Document 3 discloses a zoom lens composed of three lens groups having negative, negative, and positive refractive powers in order from the object side, dividing the first lens group into a front group and a rear group, and moving the rear group during focusing. is doing.

JP 2010-72467 A JP 2009-186570 A JP 2009-175603 A

  However, none of the optical systems disclosed in Patent Documents 1, 2, and 3 disclose or suggest image blur correction. In the present invention, a zoom lens system having a lightweight focusing lens group capable of continuously moving a lens at high speed during focusing, a lens group for correcting image blurring, and having a small and good imaging performance, and the zoom It is an object to provide an interchangeable lens apparatus including a lens system and a camera system including the imaging apparatus.

  One of the above objects is achieved by the following zoom lens system. That is, according to the present invention, in order from the object side to the image plane side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, and a succeeding group having at least one positive refractive power. The distance between the lens groups is changed during zooming, and the distance between the first lens group and the second lens group during focusing from the infinite focus state to the close object focus state is The distance between the second lens group and the lens group closest to the object side among the succeeding groups changes, and the entire succeeding group or a part of the succeeding group having the positive refractive power is optically corrected. The zoom lens system is characterized by moving in a direction perpendicular to the optical axis.

One of the above objects is achieved by the following interchangeable lens device. That is, the present invention is a zoom lens system, and in order from the object side to the image plane side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, and at least one positive lens group. And a subsequent group having refractive power, and during zooming, the distance between the lens groups is changed, and when focusing from an infinite focus state to a close object focus state, the first lens group and the second lens group The distance between the lens group and the distance between the second lens group and the lens group closest to the object among the succeeding groups are changed, and the whole or a part of the succeeding group having the positive refractive power is optically changed. A zoom lens system that moves in a direction perpendicular to the optical axis to correct image blur; and
The present invention relates to an interchangeable lens apparatus including a lens mount unit that can be connected to a camera body including an imaging element that receives an optical image formed by the zoom lens system and converts the optical image into an electrical image signal.

One of the above objects is achieved by the following camera system. That is, the present invention is a zoom lens system, and in order from the object side to the image plane side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, and at least one positive lens group. And a subsequent group having refractive power, and during zooming, the distance between the lens groups is changed, and when focusing from an infinite focus state to a close object focus state, the first lens group and the second lens group The distance between the lens group and the distance between the second lens group and the lens group closest to the object among the succeeding groups are changed, and the whole or a part of the succeeding group having the positive refractive power is optically changed. An interchangeable lens apparatus including a zoom lens system that moves in a direction perpendicular to the optical axis in order to correct image blur; and
A camera body including an image sensor that is detachably connected to the interchangeable lens device via a camera mount unit and receives an optical image formed by the zoom lens system and converts the optical image signal into an electrical image signal image signal; The present invention relates to a camera system.

  According to the present invention, a compact zoom lens system capable of high-speed autofocus capable of supporting moving image shooting with a maximum field angle of about 80 °, good imaging characteristics, and image blur correction during shooting by lens shift. Can be provided.

Lens arrangement diagram of zoom lens system according to Embodiment 1 Longitudinal aberration diagram in the infinite focus state of the zoom lens system according to Embodiment 1 Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Embodiment 1 Lens arrangement diagram of zoom lens system according to Embodiment 2 Longitudinal aberration diagram of zoom lens system according to Embodiment 2 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Embodiment 2 Lens arrangement diagram of zoom lens system according to Embodiment 3 Longitudinal aberration diagram of the zoom lens system according to Embodiment 3 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Embodiment 3 Lens arrangement diagram of zoom lens system according to Embodiment 4 Longitudinal aberration diagram of zoom lens system according to Embodiment 4 in an infinitely focused state Lateral aberration diagrams in the basic state where image blur correction is not performed and in the image blur correction state at the telephoto end of the zoom lens system according to Embodiment 4 Schematic configuration diagram of a camera system according to Embodiment 5

(Embodiments 1 to 4)
1, 4, 7, and 10 are lens arrangement diagrams of the zoom lens systems according to Embodiments 1 to 4, respectively. In each figure, the optical system is in an infinitely focused state. An arrow attached to the lens indicates a moving direction during focusing from an infinitely focused state to a close object focused state. The zoom lens system according to each embodiment includes, in order from the object side to the image plane side, a first lens group G1 having a negative refractive power, a second lens group G2 having a negative refractive power, a stop A, and at least a positive And a succeeding group having a refractive power of. Further, the whole or a part of the lens group that performs image blur correction is indicated by an arrow in the vertical direction. In each figure, a symbol (+) and a symbol (−) attached to a symbol of each lens group correspond to a symbol of refractive power of each lens group. In each figure, the straight line described on the rightmost side represents the position of the image plane S.

  As shown in FIG. 1, in the zoom lens system according to Embodiment 1, the first lens group G1 has a convex surface facing the object side in order from the object side, and negative refraction as moving from the optical axis to the periphery toward the image surface side. A negative lens L1 having an aspheric surface in which the radius of curvature increases in the direction in which the force decreases, and a convex surface on the object side, and the radius of curvature decreases in the direction in which positive refractive power increases from the optical axis toward the periphery on the image side. It consists of a positive lens L2 having an aspherical surface. The second lens group G2 is composed of a negative lens L3 having a convex surface on the image surface side and an aspheric surface on the image surface side. The third lens group G3 includes a positive lens L4 having a convex surface directed toward the object side and aspheric surfaces on both sides of the lens surface, a cemented lens of a negative lens L5 and a positive lens L6, a meniscus negative lens L7, and a positive lens L8. Consists of. The diaphragm A is disposed between the second lens group G2 and the third lens group G3. At the time of focusing, the second lens group G2 is moved along the optical axis. Specifically, the second lens group G2 is moved to the object side during focusing from the infinite focus state to the close object focus state. The positive lens L8 moves by a predetermined amount in a direction perpendicular to the optical axis at the time of image blur correction. The amount of movement of the image blur correction lens group is an amount for correcting the camera body shake angle equivalent to 0.3 °.

  The first lens group G1 of the first embodiment has a strong divergence action that greatly bends a light beam having an incident angle with a maximum field angle of approximately 80 ° in a direction parallel to the optical axis. Furthermore, the aspherical surface on the image plane side corrects distortion at the wide angle end well. The positive lens of L2 corrects negative lateral chromatic aberration generated in L1 in the positive direction. The aspherical surface of the negative lens L3 constituting the second lens group G2 reduces aberration fluctuations during focusing, particularly changes in field curvature. In the embodiment, L2 and L3 are made of a resin material. The third lens group G3 having a positive refractive power has a function of forming an image of the light beams from the first lens group G1 and the second lens group G2, and mainly corrects spherical aberration and coma aberration. . The positive lens L4 has two aspheric surfaces, and corrects longitudinal chromatic aberration together with the cemented lens of the negative lens L5 and the positive lens L6. The negative lens L7 corrects the negative curvature of field generated by the positive lens L4 closest to the object side of the third lens group G3. The positive lens L8 is arranged closest to the image plane side to ensure telecentricity with respect to the imaging plane.

  As shown in FIG. 4, in the zoom lens system according to Embodiment 2, the first lens group G1 includes, in order from the object side, a negative meniscus lens L1 having a convex surface directed toward the object side, a negative lens L2, and a positive refractive power. And a convex lens on the object side, and a positive lens L3 having an aspheric surface with a radius of curvature that decreases in the direction in which the positive refractive power increases toward the periphery from the optical axis toward the image surface side. The second lens group G2 includes a negative lens L4 having a convex surface directed toward the image surface side. The third lens group G3 includes a positive lens L5 having a convex surface facing the object side and an aspherical positive lens L5, a cemented lens of a negative lens L6 and a positive lens L7, a negative lens L8 having a convex surface facing the object side, and a positive lens. L9. The diaphragm A is disposed between the second lens group G2 and the third lens group G3. At the time of focusing, the second lens group G2 is moved along the optical axis. Specifically, the second lens group G2 is moved to the object side during focusing from the infinite focus state to the close object focus state. The positive lens L9 moves by a predetermined amount in a direction perpendicular to the optical axis during image blur correction. The amount of movement of the image blur correction lens group is an amount for correcting the camera body shake angle equivalent to 0.3 °.

  The first lens group G1 of the second embodiment has a strong divergence action that greatly bends a light beam having an incident angle with a maximum field angle of approximately 80 ° in a direction parallel to the optical axis. The negative lens L2 has an aspheric surface on the image plane side, and has a shape in which the negative refractive power that increases the radius of curvature decreases as the amount of deformation of the aspheric surface increases toward the periphery. In the embodiment, the edge shape of the lens periphery is very thin due to the deformation of the aspherical surface, as if it were a positive lens. The L2 aspherical lens may be formed of a resin layer and bonded to the negative lens L1 to form a composite aspherical surface, or may be configured as a plastic lens with an air gap from the negative lens L1. The positive lens L3 corrects negative lateral chromatic aberration generated in the negative lens L1 in the positive direction. The aspherical surface of the negative lens L3 constituting the second lens group G2 reduces aberration fluctuations during focusing. In the embodiment, the negative lens L2, the positive lens L3, and the negative lens L4 are made of a resin material. The third lens group G3 having a positive refractive power has a function of forming an image of the light beams from the first lens group G1 and the second lens group G2, and mainly corrects spherical aberration and coma aberration. In particular, spherical aberration and coma are favorably corrected by making the positive lens L5 double-sided aspheric. The longitudinal chromatic aberration is corrected together with the cemented lens of the negative lens L6 and the positive lens L7. The negative lens L8 corrects the negative field curvature generated by the positive lens L5 closest to the object side of the third lens group G3. The positive lens L9 is disposed closest to the image plane side to ensure telecentricity with respect to the imaging plane.

  As shown in FIG. 7, in the zoom lens system according to Embodiment 3, the first lens group G1 includes, in order from the object side, a negative lens L1 having a convex surface facing the object side, and a meniscus negative having a convex surface facing the object side. The lens L2 includes a positive lens L3 having a convex surface on the object side and an aspheric surface on the image surface side. The second lens group G2 includes a negative lens L4 having a convex surface directed toward the image surface side. The third lens group G3 includes a positive lens L5 having a convex surface directed toward the object side, a cemented lens of a negative lens L6 and a positive lens L7, a negative lens L8 having a convex surface directed toward the object side, and a positive lens L9. The diaphragm A is disposed between the second lens group G2 and the third lens group G3. At the time of focusing, the second lens group G2 is moved along the optical axis. Specifically, the second lens group G2 is moved to the object side during focusing from the infinite focus state to the close object focus state. L9 moves by a predetermined amount in the direction perpendicular to the optical axis during image blur correction. The amount of movement of the image blur correction lens group is an amount for correcting the camera body shake angle equivalent to 0.3 °.

  The first lens group G1 of Embodiment 3 has a strong divergence action that greatly bends a light beam having an incident angle with a maximum field angle of approximately 80 ° in a direction parallel to the optical axis. In particular, the aspherical surface on the image plane side of the second lens L2 corrects positive curvature of field generated by the first lens L1 and the second lens L2. The third lens L3 has a function of correcting the lateral chromatic aberration in the minus direction generated by the two negative lenses L1 and L2 on the object side. Since the first lens group G1 is composed of three lenses, various aberrations can be corrected appropriately. Optical performance can be maintained during zooming and focusing without using an aspherical surface for the negative lens L4 constituting the second lens group G2. In the embodiment, L2, L3, and L4 are made of a resin material. The third lens group G3 having a positive refractive power has a function of forming an image of the light beams from the first lens group G1 and the second lens group G2, and mainly corrects spherical aberration and coma aberration. The positive lens L5 has both aspheric surfaces, and corrects longitudinal chromatic aberration together with the cemented lens of the negative lens L6 and the positive lens L7. The negative lens L8 corrects the negative field curvature generated by the positive lens L5 closest to the object side of the third lens group G3. The positive lens L9 is disposed closest to the image plane side to ensure telecentricity with respect to the imaging plane.

  As shown in FIG. 10, in the zoom lens system according to Embodiment 4, the first lens group G1 includes a negative meniscus lens L1 having a convex surface directed toward the object side, a negative lens L2, a positive lens L3, and a negative lens L4. Become. The second lens group G2 includes a negative lens L5. The third lens group G3 includes a positive lens L6 having a convex surface directed toward the object side, a cemented lens of a negative lens L7, and a positive lens L8. The negative lens L9 includes a cemented lens that moves a predetermined amount up and down on the optical axis during image blur correction. And a positive lens L10, and a positive lens L11 having a weak refractive power. The amount of movement of the image blur correction lens group is an amount for correcting the camera body shake angle equivalent to 0.3 °. The diaphragm A is disposed between the second lens group G2 and the third lens group G3. At the time of focusing, the second lens group G2 is moved along the optical axis. Specifically, the second lens group G2 is moved to the object side during focusing from the infinite focus state to the close object focus state.

  The first lens group G1 of the fourth embodiment has a strong divergence action that greatly bends a light beam having an incident angle of about 80 ° in the direction parallel to the optical axis. The aspherical surface of the negative lens L5 constituting the second lens group G2 reduces aberration fluctuations during focusing. In the embodiment, L2 and L5 are made of a resin material. Among the third lens group G3 having positive refractive power, the cemented lens of the positive lens L6 having positive refractive power closest to the object side and the negative lens L7 and the positive lens L8 is the first lens group G1, It has a function of forming an image of a light beam from the two lens group G2, and mainly corrects spherical aberration and coma. The negative lens L9 and the positive lens L10 are cemented lenses in order to minimize color separation that occurs during image blur.

Hereinafter, conditions that are preferably satisfied by the zoom lens systems according to Embodiments 1 to 4 will be described. A plurality of preferable conditions are defined for the zoom lens system according to each embodiment, but a zoom lens system configuration that satisfies all of the plurality of conditions is most desirable. However, by satisfying individual conditions, it is possible to obtain a zoom lens system that exhibits the corresponding effects. For example, like the zoom lens system according to Embodiments 1 to 4,
In order from the object side to the image plane side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, and a succeeding group having at least one positive refractive power, and zooming At this time, the distance between the first lens group and the second lens group, the second lens group, and the second lens group are changed during focusing from the infinity state to the close object state. The distance between the succeeding group and the lens group closest to the object side changes, and the entire succeeding group or a part of the succeeding group having the positive refractive power is perpendicular to the optical axis in order to optically correct the image blur. The zoom lens system moves to

  For example, it is preferable that the zoom lens systems according to Embodiments 1 to 4 satisfy the following condition (1).

0.1 <d1w / d2w <0.4 (1)
here,
d1w: the air space between the first lens group and the second lens group in the infinitely focused state at the wide-angle end,
d2w: an air gap between the second lens group and the succeeding group in the infinitely focused state at the wide angle end.

  The condition (1) defines the air distance at the wide-angle end when the object distance between the lens arranged closest to the image plane of the first lens group and the lens arranged closest to the object side of the second lens group is infinity. To do. Exceeding the lower limit of the condition (1) is not desirable because the clearance cannot be secured at the focus position where the first lens group and the second lens group are closest to each other, and problems such as contact with mechanical parts occur. If the upper limit is exceeded, mechanical interference can be avoided, but the first lens group and the second lens group are separated from each other and the air gap is widened, which is not desirable because the effective diameter of the front lens increases and the size of the lens barrel increases. .

  The reason why the distance between the first lens group and the second lens group and the distance between the second lens group and the succeeding group are changed during focusing from an infinite object distance to a close object distance is as follows. This is because the image plane variation due to zooming is appropriately corrected by changing the group interval.

  Further, it is desirable that the second lens group move relative to the imaging surface during focusing because the overall optical length can be shortened compared to the case where the second lens group is fixed. Furthermore, it is possible to reduce degradation of optical performance during focusing.

  In addition, when the following condition (1) ′ is further satisfied, the above effect can be further achieved.

0.1 <d1w / d2w <0.35 (1) ′
When the focal length of the first lens unit is f1 and the focal length at the wide-angle end at infinity is fw, it is desirable to satisfy the condition (2).

0.9 <| f1 / fw | <5.6 (2)
The condition (2) defines the focal length of the first lens group. If the focal length is increased beyond the upper limit, the back focus is shortened and the total optical length is shortened. However, the field curvature becomes excessive in the negative direction. It becomes impossible to make a simple lens configuration. Conversely, if the focal length is shortened, it is not only difficult to correct spherical aberration, particularly at the telephoto end, but also the total optical length is undesirably increased.

  In practicing the present invention, it is desirable that the diaphragm is disposed in the succeeding group, but more desirably, it is disposed on the most object side in the succeeding group. By separating the aperture and the subsequent lens group, the workability when aligning and assembling within the subsequent group is increased without using the aperture unit, and the effect of reducing the number of assembly steps can be obtained.

  For example, it is preferable that the zoom lens systems according to Embodiments 1 to 4 satisfy the following condition (3).

0.3 <βw <0.8 (3)
here,
βw: Paraxial lateral magnification at the wide angle end of the image blur correction lens group.

  Conditional expression (3) specifies the magnification of the lens group for image blur correction, shortens the overall optical length, sets the parallel movement amount of the lens group for image blur correction to an appropriate value, and improves various aberrations. This is a condition for correcting to. If the lower limit of condition (3) is exceeded, it is advantageous to shorten the optical total length, but coma and astigmatism generated in the image blur correcting lens group becomes excessive, and these off-axis aberrations are reduced. It becomes difficult to correct in a balanced manner with other lens groups. When the upper limit of the condition (3) is exceeded, the total optical length becomes long, and the amount of parallel movement of the lens group for image blur correction at the time of camera shake correction becomes excessive, and the actuator for moving the lens group becomes large. This makes it difficult to make the lens barrel compact.

  It is desirable that the lens group for image blur correction be light, and it is preferable that the lens group is composed of one or two optical lens elements. Further, regarding the arrangement on the mechanism with the aperture unit, it is desirable that the arrangement be made at a distance of about 0 ° so that mechanical interference can be avoided.

  Each optical lens element constituting the zoom lens system according to Embodiments 1 to 4 is a refractive lens element that deflects incident light by refraction (that is, deflection is performed at the interface between media having different refractive indexes). However, the present invention is not limited to this. For example, a diffractive lens element that deflects incident light by diffraction, a refractive / diffractive hybrid lens element that deflects incident light by a combination of diffractive action and refractive action, and a refractive index that deflects incident light according to the refractive index distribution in the medium A distributed lens element or the like may be used. In particular, in a refractive / diffractive hybrid lens element, it is preferable to form a diffractive structure at the interface of media having different refractive indexes, since the wavelength dependency of diffraction efficiency is improved.

  Furthermore, in the embodiment of the present invention, the configuration of the second lens group that performs focusing is a single optical lens element, in order to reduce the weight of the focusing group in order to drive the AF at high speed. It may be made of glass, or may be a so-called hybrid lens in which a spherical polished lens is made of a resin layer. Furthermore, even if it comprises not only a glass material but a resin material, the subject of this invention can be solved.

(Embodiment 5)
FIG. 13 is a block diagram of a camera system according to the fifth embodiment. The camera system according to Embodiment 5 includes a camera body 100 and an interchangeable lens device 200.

  The camera body 100 includes a camera controller 101, an image sensor 102, a shutter unit 103, an image display control unit 104, an image sensor control unit 105, a contrast detection unit 106, a shutter control unit 107, an image recording control unit 108, a display 110, and a release button. 111, a memory 112, a power source 113, and a camera mount 114.

  The camera controller 101 is an arithmetic device that controls the entire camera system. The camera controller 101 is electrically connected to the image display control unit 104, the image sensor control unit 105, the contrast detection unit 106, the shutter control unit 107, the image recording control unit 108, the memory 112, and the camera mount 114. Thus, signals can be exchanged with each other. The camera controller 101 is electrically connected to the release button 111 and receives a signal generated by operating the release button 111. Furthermore, the camera controller 101 is connected to a power source 113.

  The imaging sensor 102 is, for example, a C-MOS sensor. The imaging sensor 102 converts the optical image incident on the light receiving surface into image data and outputs the image data. The image sensor 102 is driven in accordance with a drive signal from the image sensor control unit 105. The image sensor control unit 105 outputs a drive signal for driving the image sensor 102 according to a control signal from the camera controller 101 and outputs image data output from the image sensor 102 to the camera controller 101. The contrast detection unit 106 calculates and detects contrast from image data output from the image sensor 102 in accordance with a control signal from the camera controller 101, and outputs the contrast to the camera controller 101.

  The shutter unit 103 includes a shutter plate that blocks an optical path of image light incident on the image sensor 102. The shutter unit 103 is driven in accordance with a drive signal from the shutter control unit 107. The shutter control unit 107 controls the opening / closing timing of the shutter plate of the shutter unit 103 in accordance with a control signal from the camera controller 101.

  The display 110 is, for example, a liquid crystal display device. The display 110 is driven in accordance with a drive signal from the image display control unit 104 and displays an image on the display surface. The image display control unit 104 outputs image data to be displayed on the display 110 and a drive signal for driving the display in accordance with a control signal from the camera controller 101.

  The image recording control unit 108 outputs the image data to the detachably connected memory card 109 in response to a control signal from the camera controller 101.

  The camera mount 114 mechanically connects the camera body 200 and an interchangeable lens device 200 described later. The camera mount 114 also functions as an interface for electrically connecting the camera body 200 and an interchangeable lens device 200 described later.

  The interchangeable lens apparatus 200 includes a lens controller 201, an image blur control unit 202, an aperture control unit 203, a focus control unit 204, a zoom control unit 205, a memory 206, a blur detection unit 207, an aperture unit 208, a zoom lens system 209, and a lens mount. 210.

  The lens controller 201 is an arithmetic device that controls the entire interchangeable lens device 200, and is connected to the camera controller 101 in the camera body described above via the lens mount 210 and the camera mount 114. The lens controller 201 is electrically connected to the image blur control unit 202, the aperture control unit 203, the focus control unit 204, the zoom control unit 205, the memory 206, and the blur detection unit 207, and can exchange signals with each other.

  The zoom lens system 209 is the zoom lens system of Embodiment 1 described above. The zoom lens system 209 includes a lens group 209a, a lens group 209b, and a lens group 209c. The zoom lens system 209 performs zooming by moving the lens groups 209a, 209b, and 209c in a direction along the optical axis. The zoom lens system 209 performs focusing by moving the focusing lens group 209b in a direction along the optical axis. The zoom lens system 209 performs image blur correction by moving the image blur correction lens group 209c in a direction orthogonal to the optical axis.

  The image blur control unit 202 detects and outputs the current position of the image blur correction lens group 209c according to a control signal from the lens controller 201. Further, the image blur control unit 202 outputs a drive signal for driving the image blur correction lens group 209c, and drives the image blur correction lens group 209c in a direction orthogonal to the optical axis.

  The diaphragm control unit 203 detects and outputs the current position of the diaphragm unit 208 in accordance with a control signal from the lens controller 201. The diaphragm control unit 203 outputs a drive signal for driving the diaphragm blades included in the diaphragm unit 208 to open and close the diaphragm, thereby changing the F number of the optical system.

  The focus control unit 204 detects and outputs the current position of the focusing lens group 209b in accordance with a control signal from the lens controller 201. Further, the focus control unit 204 outputs a driving signal for driving the focusing group 209b, and drives the focusing lens group 209b in a direction along the optical axis.

  The zoom control unit 205 detects and outputs the current positions of the zoom lens groups 209a, 209b, and 209c according to a control signal from the lens controller 201. The zoom control unit 205 outputs a drive signal for driving the zoom lens groups 209a, 209b, and 209c, and drives the zoom lens groups 209a, 209b, and 209c in a direction along the optical axis.

  In the above configuration, when the release button 111 is half-pressed, the camera controller 101 executes an autofocus routine. First, the camera controller 101 communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, and the zoom lens groups 209 a, 209 b and 209 c, the focusing lens group 209 b, the image blur correction lens group 209 c, and the aperture unit 208. Detect state.

  Next, the camera controller 101 communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, and outputs a control signal for driving the focusing lens group 209 b to the lens controller 201. The lens controller 201 controls the focus control unit 204 based on the control signal to drive the focusing lens group 209b. The camera controller 101 simultaneously communicates with the lens controller 201 via the camera mount 114 and the lens mount 210, and outputs a control signal that instructs the lens controller 201 so that the aperture value becomes a predetermined value. The lens controller 201 controls the diaphragm control unit 203 based on the control signal to drive the diaphragm blades of the diaphragm unit 208 so as to have a predetermined F number.

  On the other hand, the camera controller 101 outputs control signals to the image sensor control unit 105 and the contrast detection unit 106. The image sensor control unit 105 and the contrast detection unit 106 obtain the output from the image sensor 102 in association with the sampling frequency of the wobbling drive of the focusing lens group 209b. The image sensor control unit 105 transmits image data corresponding to the optical image to the camera controller 101 based on a control signal from the camera controller 101. The camera controller 101 performs predetermined image processing on the image data and transmits the image data to the image display control unit 104. The image display control unit 104 displays the image data on the display 110 as a visible image.

In addition, the contrast detection unit 106 calculates the contrast value of the image data in association with the wobbling and transmits it to the camera controller 101. Based on the detection result of the contrast detection unit 106, the camera controller 101 determines the focusing movement direction and the movement amount of the focusing lens group to the lens controller 201, and transmits information regarding these to the lens controller 201. The lens controller 201 outputs a control signal to the focus control unit 204 so as to move the focusing lens group 209b.
The focus control unit 204 drives the focusing lens group 209b based on a control signal from the lens controller 201.

  In the first embodiment described above, the example in which the zoom lens system described in the first embodiment is applied as the zoom lens system has been described. However, the zoom lens system according to another embodiment may be applied. Needless to say.

  Hereinafter, numerical examples in which the zoom lens systems according to Embodiments 1 to 4 are specifically implemented will be described. As will be described later, Numerical Examples 1 to 4 correspond to Embodiments 1 to 4, respectively. In each numerical example, the unit of length in the table is “mm”, and the unit of angle of view is “°”. In each numerical example, r is a radius of curvature, d is a surface interval, nd is a refractive index with respect to the d line, and vd is an Abbe number with respect to the d line.

  2, 4, 6 and 8 are longitudinal aberration diagrams of the zoom lens systems according to Embodiments 1 to 4 in an infinitely focused state, respectively.

  In each longitudinal aberration diagram, spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)) are shown in order from the left side. In the spherical aberration diagram, the vertical axis represents the F number (indicated by F in the figure), the solid line is the d line (d-line), the short broken line is the F line (F-line), and the long broken line is the C line (C- line). In the astigmatism diagram, the vertical axis represents the image height (indicated by H in the figure), the solid line represents the sagittal plane (indicated by s), and the broken line represents the meridional plane (indicated by m in the figure). is there. In the distortion diagram, the vertical axis represents the image height (indicated by H in the figure).

  Here, κ is a conic constant, and A4, A6, A8, and A10 are fourth-order, sixth-order, eighth-order, and tenth-order aspheric coefficients, respectively.

(Numerical example 1)
The zoom lens system of Numerical Example 1 corresponds to Embodiment 1 shown in FIG.

  Table 1 shows surface data of the zoom lens system of the numerical value example 1.

(Table 1)
Surface data Surface number rd nd vd
Object ∞
1 104.79360 1.70000 1.75039 45.5
2 * 14.11960 7.23930
3 53.48700 4.20890 1.63185 23.4
4 * -64.32310 variable
5 -20.74670 1.00000 1.54360 56.0
6 * -70.85060 variable
7 (Aperture) ∞ 1.50000
8 * 17.18620 2.47040 1.60820 57.8
9 * 104.78870 0.20000
10 26.67370 0.80000 1.72342 38.0
11 12.16250 4.96930 1.62041 60.3
12 -16.62090 0.20000
13 -242.00890 0.81840 1.70154 41.1
14 11.95320 4.29260
15 41.58320 1.76430 1.51680 64.2
16 -346.67830 BF
Image plane ∞

Aspheric data 2nd surface
K = 0.00000E + 00, A4 = -2.28690E-05, A6 = -8.21557E-08, A8 = -3.65299E-10
A10 = -1.97419E-12
4th page
K = 0.00000E + 00, A4 = -6.82611E-06, A6 = -5.54081E-08, A8 = 6.42339E-10
A10 = -4.30705E-12
6th page
K = 0.00000E + 00, A4 = -1.11598E-05, A6 = 1.17977E-07, A8 = -1.73302E-09
A10 = 1.59732E-11
8th page
K = 0.00000E + 00, A4 = -8.23363E-05, A6 = -1.23544E-06, A8 = -1.87392E-08
A10 = -4.33067E-10
9th page
K = 0.00000E + 00, A4 = 2.93472E-05, A6 = -7.23152E-07, A8 = -3.72748E-08
A10 = -2.87250E-11

Various data Zoom ratio 2.80014
Wide angle Medium telephoto Focal length 14.3987 24.0939 40.3185
F number 3.60517 4.70020 5.76812
Angle of view 40.0710 24.8202 15.1230
Image height 10.8150 10.8150 10.8150
Total lens length 94.3552 89.5957 97.5656
BF 29.09953 39.82728 57.55796
d4 6.5172 7.1216 6.7444
d6 27.5753 11.4836 2.1000

Zoom lens group data Group Start surface Focal length
1 1 -61.63434
2 5 -54.35067
3 7 24.97327

(Numerical example 2)
The zoom lens system of Numerical Example 2 corresponds to Embodiment 2 shown in FIG.

  Table 2 shows surface data of the zoom lens system of the numerical value example 2.

(Table 2)
Surface number rd nd vd
Object ∞
1 86.66020 1.30000 1.77250 49.6
2 14.23360 0.20000
3 14.23360 1.50000 1.54360 56.0
4 * 13.98030 6.47290
5 44.00630 3.97150 1.63185 23.4
6 * -107.54900 variable
7 -19.75230 1.00000 1.54360 56.0
8 * -57.34390 Variable
9 (Aperture) ∞ 1.50000
10 * 16.46360 2.67980 1.60820 57.8
11 * 117.74390 0.20000
12 27.76630 0.80000 1.72342 38.0
13 11.46000 4.91930 1.62041 60.3
14 -19.44130 0.20000
15 186.21390 0.82000 1.70154 41.1
16 11.91570 3.45530
17 39.95880 1.70650 1.51823 59.0
18 -2076.12290 BF
Image plane ∞

Aspheric data 4th surface
K = 0.00000E + 00, A4 = -3.03043E-05, A6 = -8.47979E-08, A8 = -1.16725E-09
A10 = -8.95427E-13
6th page
K = 0.00000E + 00, A4 = -1.04340E-05, A6 = -4.00762E-08, A8 = 1.10491E-09
A10 = -6.24852E-12
8th page
K = 0.00000E + 00, A4 = -7.49541E-06, A6 = 1.07579E-07, A8 = -3.60542E-09
A10 = 4.32910E-11
10th page
K = 0.00000E + 00, A4 = -7.82234E-05, A6 = -7.69569E-07, A8 = -1.61880E-08
A10 = -2.82006E-10
11th page
K = 0.00000E + 00, A4 = 1.66125E-05, A6 = -5.23175E-07, A8 = -2.79224E-08
A10 = -5.43633E-11

Various data Zoom ratio 2.85000
Wide angle Medium telephoto Focal length 14.4003 24.3094 41.0409
F number 3.60552 4.70092 5.76896
Angle of View 40.0747 24.6547 14.8746
Image height 10.8150 10.8150 10.8150
Total lens length 93.5139 89.3875 97.5680
BF 29.35072 40.34810 58.48252
d6 8.3405 7.7763 6.1602
d8 25.0974 10.5378 2.2000

Zoom lens group data Group Start surface Focal length
1 1 -52.27574
2 7 -55.95287
3 9 24.16783

(Numerical Example 3)
The zoom lens system of Numerical Example 3 corresponds to Embodiment 3 shown in FIG.

  Table 3 shows surface data of the zoom lens system according to Numerical Example 3.

(Table 3)
Surface number rd nd vd
Object ∞
1 63.22440 1.30000 1.58913 61.3
2 14.59190 4.77520
3 30.58660 1.49020 1.54360 56.0
4 * 14.14470 3.84470
5 22.28760 3.73960 1.60740 27.0
6 * 160.05920 variable
7 -22.83810 1.00000 1.54360 56.0
8 * -58.05490 Variable
9 (Aperture) ∞ 1.50000
10 * 15.54220 2.94430 1.60820 57.8
11 * 285.73990 0.34260
12 36.79150 0.80000 1.72342 38.0
13 12.53930 4.68890 1.62041 60.3
14 -19.35440 0.20000
15 161.87650 0.82000 1.70154 41.1
16 11.68540 5.34910
17 38.09310 1.74340 1.51680 64.2
18 436.05980 BF
Image plane ∞

Aspheric data 4th surface
K = 0.00000E + 00, A4 = -5.44576E-05, A6 = -1.58151E-07, A8 = -2.27016E-09
A10 = 4.84012E-12
6th page
K = 0.00000E + 00, A4 = 7.93874E-06, A6 = -8.26366E-09, A8 = 1.86616E-09
A10 = -1.39326E-11
8th page
K = 0.00000E + 00, A4 = -7.30182E-06, A6 = -3.86910E-08, A8 = 1.32208E-09
A10 = -3.59227E-12
10th page
K = 0.00000E + 00, A4 = -7.39950E-05, A6 = -7.01861E-07, A8 = -1.93716E-08
A10 = -2.14383E-10
11th page
K = 0.00000E + 00, A4 = 2.62799E-05, A6 = -4.87820E-07, A8 = -3.02852E-08
A10 = -6.92452E-12

Various data Zoom ratio 2.84990
Wide angle Medium telephoto Focal length 14.4004 24.3105 41.0398
F number 3.60556 4.70060 5.76820
Angle of view 40.1327 24.6300 14.8690
Image height 10.8150 10.8150 10.8150
Total lens length 96.8142 91.7920 101.0672
BF 28.42988 39.58654 58.44785
d6 6.5947 6.0960 5.8814
d8 27.2516 11.5715 2.2000

Zoom lens group data Group Start surface Focal length
1 1 -43.60023
2 7 -69.95750
3 9 25.25487

(Numerical example 4)
The zoom lens system of Numerical Example 4 corresponds to Embodiment 4 shown in FIG.

  Table 4 shows surface data of the zoom lens system of the numerical value example 4.

(Table 4)
Surface number rd nd vd
Object ∞
1 61.71270 1.30000 1.58913 61.3
2 14.62050 4.01940
3 29.88820 1.49360 1.54360 56.0
4 * 18.94550 4.34900
5 59.37300 3.24520 1.80518 25.5
6 -76.99860 0.20000
7 -67.17730 0.90000 1.71300 53.9
8 -121.81040 Variable
9 -16.86220 1.00000 1.54360 56.0
10 * -53.56120 Variable
11 (Aperture) ∞ 1.50000
12 * 14.78400 3.66620 1.60820 57.8
13 * -63.50450 1.74700
14 263.03310 0.80000 1.80610 40.7
15 13.34730 4.78130 1.58913 61.3
16 -15.93620 0.51890
17 128.93680 0.80000 1.72342 38.0
18 11.65180 1.94400 1.48749 70.4
19 16.04170 Variable
20 26.56180 1.95010 1.71736 29.5
21 44.82240 BF
Image plane ∞

Aspheric data 4th surface
K = 0.00000E + 00, A4 = -3.87598E-05, A6 = -9.83871E-08, A8 = -7.72283E-10
A10 = 8.35102E-13
10th page
K = 0.00000E + 00, A4 = -1.38354E-05, A6 = -4.23848E-08, A8 = 2.93893E-09
A10 = -3.32442E-11
12th page
K = 0.00000E + 00, A4 = 2.58463E-06, A6 = 7.86089E-07, A8 = -7.28990E-09
A10 = 1.81771E-10
Side 13
K = 0.00000E + 00, A4 = 1.39108E-04, A6 = 8.83724E-07, A8 = -5.40431E-09
A10 = 2.09785E-10

Various data Zoom ratio 2.84994
Wide angle Medium telephoto Focal length 14.3993 24.3086 41.0372
F number 3.60528 4.70065 5.76786
Angle of View 40.0334 24.6931 14.8726
Image height 10.8150 10.8150 10.8150
Total lens length 93.0668 90.7845 101.5571
BF 19.50304 31.34773 51.33382
d8 5.2347 5.6005 5.9599
d10 24.5736 10.5130 2.2000
d19 9.5408 9.1086 7.8487

Zoom lens group data Group Start surface Focal length
1 1 -59.17648
2 9 -45.71076
3 11 25.48156
4 20 87.00553

Table 5 below shows corresponding values of the respective conditions in the zoom lens system according to each numerical example.

Table 5 (Corresponding values of conditions: Numerical Examples 1 to 4)
Example 1 Example 2 Example 3 Example 4
(1) d1w / d2w 0.24 0.33 0.24 0.21
(2) | F1 / FW | 4.28 3.63 3.03 4.11
(3) βw 0.58 0.60 0.63 2.73

  The zoom lens system according to the present invention is applicable to an interchangeable lens camera system, a surveillance camera in a surveillance system, a Web camera, an in-vehicle camera, and the like, and in particular, a zoom lens system that requires high image quality such as an interchangeable lens camera system. It is suitable for.

L1 1st lens element L2 2nd lens element L3 3rd lens element L4 4th lens element L5 5th lens element L6 6th lens element L7 7th lens element L8 8th lens element L9 9th lens element L10 10th lens element L11 11th lens element A Aperture stop S Image surface 100 Lens interchangeable digital camera system 101 Camera body 102 Image sensor 110 Liquid crystal monitor 114 Camera mount unit 200 Interchangeable lens device 209 Zoom lens system 210 Lens mount unit

Claims (7)

  A zoom lens system, which has, in order from the object side to the image plane side, a first lens group having a negative refractive power, a second lens group having a negative refractive power, and at least one positive refractive power A distance between the first lens group and the second lens group at the time of focusing from the infinite focus state to the close object focus state. The distance between the second lens group and the lens group closest to the object side among the succeeding groups changes, and the entire succeeding group or a part of the succeeding group having the positive refractive power is optically corrected. Zoom lens system that moves in the direction perpendicular to the optical axis. The zoom lens system according to claim 1, satisfying the following condition (1):
0.1 <d1w / d2w <0.4 (1)
here,
d1w: the distance between the first lens group and the second lens group at the wide-angle end when focusing on infinity,
d2w: the distance between the second lens group and the third lens group at the wide-angle end when focusing on infinity. The zoom lens system according to claim 1, satisfying the following condition (2):
0.9 <| f1 / fw | <5.6 (2)
here,
f1: the focal length of the first lens group,
fW: focal length of the entire system at the optical end.   2. The zoom lens system according to claim 1, wherein a diaphragm is disposed between the second lens group and the third lens group. The zoom lens system according to claim 1, satisfying the following condition (3):
0.3 <βw <0.8 (3)
here,
βw: Paraxial lateral magnification at the wide-angle end of the lens unit that moves in the direction perpendicular to the optical axis in order to optically correct image blur. A zoom lens system according to claim 1;
An interchangeable lens apparatus comprising: a lens mount portion that can be connected to a camera body including an image sensor that receives an optical image formed by the zoom lens system and converts the optical image into an electrical image signal. An interchangeable lens device comprising the zoom lens system according to claim 1;
A camera system comprising: a camera body including an imaging device that is detachably connected to the imaging device via a camera mount unit and that receives an optical image formed by the zoom lens system and converts the optical image into an electrical image signal.

Images