JP2017207665A - Variable power optical system and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized variable power optical system and an imaging apparatus having a high variable power ratio and good optical performance over the whole variable power range.SOLUTION: A variable power optical system according to the present invention includes, successively disposed from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a subsequent lens group having a positive refractive power as a whole. Upon varying power from a wide angle end to a telephoto end, at least the second lens group G2 is moved so as to increase the interval between the first lens group G1 and the second lens group G2 and to decrease the interval between the second lens group G2 and the third lens group G3. The variable power optical system has at least one predetermined lens and satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a variable power optical system and an image pickup apparatus, and more particularly to a variable power optical system and an image pickup apparatus suitable for an image pickup apparatus using a solid-state image pickup device (CCD, CMOS, etc.) such as a digital still camera or a digital video camera.

  Conventionally, imaging devices using solid-state imaging devices such as digital still cameras and digital video cameras have been widely used. As an optical system used in such an imaging apparatus, a variable magnification optical system capable of changing a focal length is widely used. The variable magnification optical system is widely adopted as an optical system of a monitoring imaging apparatus. If a variable magnification optical system having a high variable magnification ratio is used, the focal length can be adjusted according to the monitoring area and the like, so that it is easy to meet various needs. Further, since the monitoring imaging device is always used, a bright variable magnification optical system having a large aperture is required. This is because a large-aperture variable magnification optical system can obtain a clear subject image even in a time zone with a small amount of light.

  As such a variable magnification optical system, conventionally, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power are provided. Many zoom lenses including a third lens group and a subsequent lens group including a lens group having a positive refractive power have been proposed (see, for example, Patent Document 1 and Patent Document 2).

Japanese Patent No. 4672860 Japanese Patent No. 4823680

  In recent years, in addition to the above requirements, a variable magnification optical system having better optical performance has been demanded. This is because a high-resolution variable magnification optical system capable of confirming a finer feature of a subject has been demanded because the solid-state imaging device has increased in pixels and sensitivity. Further, there is a great demand for downsizing of the monitoring imaging apparatus, and downsizing of the variable power optical system is also strongly demanded.

  However, the conventional variable magnification optical system cannot satisfy these requirements. If a further reduction in size of the zooming optical system is attempted, aberration fluctuations increase over the entire zooming range, making it difficult to achieve good optical performance over the entire zooming range.

  An object of the present invention is to provide a small zoom optical system and an image pickup apparatus that have a high zoom ratio and have good optical performance over the entire zoom range.

  In order to solve the above problem, a variable magnification optical system according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive lens, which are sequentially arranged from the object side. A third lens group having a refractive power and a subsequent lens group having a positive refractive power as a whole, and an interval between the first lens group and the second lens group at the time of zooming from the wide-angle end to the telephoto end Is increased, and at least the second lens group is moved so that the distance between the second lens group and the third lens group is decreased, and a predetermined condition that satisfies the following conditional expressions (1) and (2) is satisfied. At least one lens, and satisfies the following conditional expressions (3) and (4).

(1) 1.93 <nd
(2) 23.0 <vd
(3) 0.7 <| F2 / Fw | <1.45
(4) 0.1 <F1 / Ft <0.4

However,
nd is a refractive index with respect to the d-line (wavelength 587.6 nm) of the predetermined lens;
vd is an Abbe number with respect to the d-line (wavelength 587.6 nm) of the predetermined lens;
F1 is a focal length of the first lens group,
F2 is a focal length of the second lens group,
Fw is the focal length of the entire variable magnification optical system at the wide angle end,
Ft is the focal length of the entire variable magnification optical system at the telephoto end.

  In order to solve the above problems, an imaging apparatus according to the present invention includes a variable magnification optical system according to the present invention, and an optical image formed by the variable magnification optical system on the image side of the variable magnification optical system. And an image sensor for converting the signal into an electrical signal.

  According to the present invention, it is possible to provide a small zooming optical system and an imaging apparatus that have a high zooming ratio and good optical performance over the entire zooming range.

It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 1 of this invention, an upper stage shows a wide angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the variable magnification optical system of Example 1 is focused at infinity in the wide-angle end focused state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 1 is focused at infinity in the intermediate focal position focused state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 1 is in focus at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 2 of this invention, an upper stage shows a wide angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 7 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the variable magnification optical system of Example 2 is focused at infinity in the wide-angle end focused state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 2 is focused at infinity in the intermediate focal position focused state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of focusing at infinity in the telephoto end in-focus state of the variable magnification optical system of Example 2. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 3 of this invention, an upper stage shows a wide-angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 3 is in focus at infinity in the wide-angle end focused state. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of focusing on infinity in the intermediate focal position focused state of the variable magnification optical system of Example 3. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 3 is focused at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 4 of this invention, an upper stage shows a wide-angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the variable magnification optical system of Example 4 is focused at infinity in the wide-angle end focused state. FIG. 10 is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of focusing at infinity in the intermediate focal position focused state of the variable magnification optical system of Example 4. FIG. 6 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram when the zoom lens of Example 4 is in focus at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 5 of this invention, an upper stage shows a wide-angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 5 is focused at infinity in the wide-angle end focused state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of focusing on infinity in the intermediate focal position focused state of the variable magnification optical system of Example 5. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 5 is focused at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 6 of this invention, an upper stage shows a wide angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 12 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 6 is focused at infinity in the wide-angle end focused state. FIG. 10 is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of focusing at infinity in the intermediate focal position focused state of the variable magnification optical system of Example 6. FIG. 12 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 6 is in focus at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 7 of this invention, an upper stage shows a wide-angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram at the time of focusing on infinity in the wide-angle end focused state of the variable magnification optical system of Example 7. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 7 is focused at infinity in the intermediate focal position focused state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 7 is focused at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 8 of this invention, an upper stage shows a wide-angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 8 is focused at infinity in the wide-angle end focused state. FIG. 10 is a spherical aberration diagram, astigmatism diagram, and distortion diagram at the time of focusing at infinity in the intermediate focal position focused state of the variable magnification optical system of Example 8. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 8 is in focus at infinity in the telephoto end in-focus state. It is sectional drawing which shows the lens structural example of the variable magnification optical system of Example 9 of this invention, an upper stage shows a wide angle end focusing state, a middle stage shows an intermediate focus position focusing state, and a lower stage shows a telephoto end focusing state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 9 is focused at infinity in the wide-angle end focused state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 9 is focused at infinity in the intermediate focus position focused state. FIG. 10 is a spherical aberration diagram, an astigmatism diagram, and a distortion diagram when the zoom lens of Example 9 is focused at infinity in the telephoto end in-focus state. It is a schematic diagram which shows an example of the imaging device which concerns on this invention.

  Hereinafter, embodiments of the variable magnification optical system and the imaging apparatus according to the present invention will be described. However, the variable magnification optical system and the imaging apparatus described below are one aspect of the variable magnification optical system and the imaging apparatus according to the present invention, and the variable magnification optical system according to the present invention is limited to the following aspects. is not.

1. Variable magnification optical system 1-1. First, an embodiment of a variable magnification optical system according to the present invention will be described. The variable magnification optical system according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side. And a subsequent lens group having a positive refractive power as a whole, and the distance between the first lens group and the second lens group is increased during zooming from the wide-angle end to the telephoto end, and the second lens At least one second lens group is moved so that the distance between the group and the third lens group is small, and at least one predetermined lens satisfying conditional expressions (1) and (2) described later is provided. Further, it satisfies the following conditional expression (3) and conditional expression (4). First, the configuration of the optical system according to the present invention will be described, and matters relating to conditional expressions will be described later. By adopting this configuration and satisfying the predetermined conditional expressions (1) to (4), the zoom lens has a high zoom ratio and good optical performance over the entire zoom range. It becomes possible to provide a system.

(1) First Lens Group The specific lens configuration of the first lens group is not particularly limited as long as it has a positive refractive power as a whole. Further, the operation of the first lens group at the time of zooming from the wide-angle end to the telephoto end is not particularly limited, and the first lens group may be a fixed group that is fixed in the optical axis direction. The moving group may be moved in the optical axis direction. However, from the viewpoint that it becomes easy to reduce the size and weight of the entire zooming optical system, it is possible to fix the first lens unit in the optical axis direction during zooming from the wide-angle end to the telephoto end. preferable. In the variable magnification optical system, the first lens group is composed of a lens having a large outer diameter and is heavy because it includes many positive lenses compared to the other lens groups. Therefore, if the first lens group is a fixed group during zooming, it is easy to reduce the size and weight of the moving mechanism for moving the lens group during zooming. This is because it becomes easy to reduce the size and weight of the entire system.

(2) Second Lens Group As long as the second lens group has a negative refractive power as a whole, the specific lens configuration is not particularly limited. At the time of zooming from the wide-angle end to the telephoto end, at least the second lens so that the distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is decreased. Move the group. In the zoom optical system, the second lens group functions as a variator, and the focal length of the zoom optical system is changed by moving the second lens group. The direction of movement of the second lens group is not particularly limited, but when the first lens group is fixed in the optical axis direction during zooming, the second lens group is moved to the image side.

(3) Third Lens Group The specific lens configuration of the third lens group is not particularly limited as long as it has a positive refractive power as a whole. Further, the operation of the third lens group at the time of zooming from the wide-angle end to the telephoto end is not particularly limited, and the third lens group may be a fixed group that is fixed in the optical axis direction. The moving group may be moved in the optical axis direction. However, if the third lens group is a fixed group, a moving mechanism for moving the third lens group at the time of zooming becomes unnecessary, so that the entire zooming optical system can be reduced in size and weight. For this purpose, the third lens group is preferably a fixed group.

(4) Subsequent Lens Group The specific lens configuration of the subsequent lens group is not particularly limited as long as it has a positive refractive power as a whole. Further, as long as the subsequent lens group has a positive refractive power as a whole, the subsequent lens group may be composed of a single lens group or a plurality of lens groups.

  The operation of the subsequent lens group at the time of zooming from the wide-angle end to the telephoto end is not particularly limited, and the subsequent lens group may be a fixed group that is fixed in the optical axis direction, or the optical axis. It may be a moving group that moves in the direction. Further, when the subsequent lens group includes a plurality of lens groups, each lens group may be a fixed group or a moving group. The subsequent lens group is composed of a plurality of lens groups, and at least a part of the lens group functions as a compensator, so that even when a high zoom ratio is realized, good optical performance is realized over the entire zoom range. Is preferable because it becomes easier.

  Further, it is preferable to perform focusing from infinity to a near object by moving all or part of the subsequent lens group. In the variable magnification optical system, the subsequent lens group can be made smaller and lighter than the first to third lens groups. Therefore, if all or part of the subsequent lens group is used as the focusing group, the focusing group can be reduced in size and weight. In addition, the amount of movement of the focusing group during focusing can be reduced. Therefore, a quick focusing operation can be performed. In addition, by reducing the size and weight of the focusing group, it becomes easy to reduce the size and weight of the drive mechanism for moving the focusing group. , Making weight reduction easy.

  When the subsequent lens group includes a plurality of lens groups, for example, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. The sixth lens group.

  Further, when the subsequent lens group is composed of a plurality of lens groups, for example, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, arranged in order from the object side, and a negative lens group. It can also have a 6th lens group of refractive power.

  According to these configurations, even when a high zoom ratio is realized, it is possible to reduce the size of the zoom optical system, and it is easier to realize good optical performance over the entire zoom range. In any of the above cases, another lens group such as a seventh lens group having positive or negative refractive power may be provided on the image side of the sixth lens group.

(5) Aperture stop The arrangement of the aperture stop in the variable magnification optical system according to the present invention is not particularly limited. However, from the viewpoints of downsizing the variable magnification optical system and realizing brighter and better optical performance, the aperture stop is on the object side of the third lens group, in the third lens group, or in the third lens group. It is preferable to be arranged on the image side.

(6) Anti-Vibration Lens Group Among the lens groups constituting the variable magnification optical system, any one lens group, or a part of the lens group is moved in the direction perpendicular to the optical axis, so that an image is captured. You may comprise as an anti-vibration lens group which correct | amends image blurring.

1-2. Conditional Expressions Next, conditions that should be satisfied by the variable magnification optical system or conditions that are preferably satisfied will be described.

  The variable magnification optical system has at least one predetermined lens that satisfies the following conditional expressions (1) and (2), and satisfies the following conditional expressions (3) and (4): It is characterized by. The predetermined lens refers to a lens made of a glass material that satisfies the following conditional expressions (1) and (2), and the variable power optical system only needs to have at least one predetermined lens, You may have a some predetermined lens.

(1) 1.93 <nd
(2) 23.0 <vd
(3) 0.7 <| F2 / Fw | <1.45
(4) 0.1 <F1 / Ft <0.4

However,
nd is a refractive index with respect to d-line (wavelength 587.6 nm) of a predetermined lens,
vd is an Abbe number with respect to the d-line (wavelength 587.6 nm) of a predetermined lens,
F1 is the focal length of the first lens group,
F2 is the focal length of the second lens group,
Fw is the focal length of the entire variable magnification optical system at the wide angle end,
Ft is the focal length of the entire variable magnification optical system at the telephoto end.

1-2-1. Conditional expression (1)
Conditional expression (1) is an expression that defines the refractive index with respect to the d-line of the glass material constituting the predetermined lens. Since the variable magnification optical system has at least one predetermined lens made of a glass material that satisfies the conditional expression (1), it is possible to reduce the size even when a high zoom ratio is realized, and at the time of zooming The fluctuation of spherical aberration and the fluctuation of astigmatism can be suppressed.

  On the other hand, when the variable magnification optical system does not include any predetermined lens that satisfies the conditional expression (1), when a high zoom ratio is realized, a small number of lenses can be used, and spherical aberration at the time of zooming. It becomes difficult to suppress fluctuations in astigmatism and astigmatism. Therefore, in order to achieve good optical performance over the entire zoom range, it is necessary to increase the number of lens groups or the number of lenses constituting each lens group, and to reduce the size of the zoom optical system. It becomes difficult to plan.

  In obtaining these effects, the lower limit of conditional expression (1) is preferably 1.94, and more preferably 1.95. As the lower limit of conditional expression (1) is larger, better optical performance can be obtained over the entire zoom range. In order to secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (1) to 2.800. The variable magnification optical system has at least one lens made of a glass material having a numerical value of conditional expression (1) of 2.800 or less, thereby sufficiently securing the visible light transmittance to the predetermined lens. be able to.

1-2-2. Conditional expression (2)
Conditional expression (2) is an expression that prescribes the Abbe number for the d-line of the glass material constituting the predetermined lens. Since the variable magnification optical system has at least one predetermined lens made of a glass material that satisfies the conditional expression (2), it is possible to reduce the size even when a high zoom ratio is realized, and at the time of zooming The fluctuation of axial chromatic aberration and the fluctuation of lateral chromatic aberration can be suppressed.

  On the other hand, when the variable magnification optical system does not include any predetermined lens that satisfies the conditional expression (2), when a high variable magnification ratio is realized, a small number of lenses can be used. It becomes difficult to suppress fluctuations in chromatic aberration and lateral chromatic aberration. Therefore, in order to achieve good optical performance over the entire zoom range, it is necessary to increase the number of lens groups or the number of lenses constituting each lens group, and to reduce the size of the zoom optical system. It becomes difficult to plan.

  In obtaining these effects, the lower limit of conditional expression (1) is preferably 24.0, and more preferably 25.0. As the lower limit of conditional expression (2) is larger, better optical performance can be obtained over the entire zoom range. In order to further secure the effect of the present invention, it is more preferable that the upper limit value of conditional expression (2) is 50.0. In the variable magnification optical system, the numerical value of conditional expression (2) is 50.0. By having at least one lens composed of the following glass materials, fluctuations in axial chromatic aberration and magnification chromatic aberration that occur in lenses other than the predetermined lens at the time of zooming can be suppressed, resulting in higher optical performance. Can be realized.

  However, in the variable magnification optical system, the predetermined lens is made of a glass material that satisfies both the conditional expressions (1) and (2) as described above.

  The predetermined lens may be included in any one or more of the first to third lens groups and the subsequent lens group. If the predetermined lens is included in any one or more of the lens groups constituting the variable magnification optical system, the above effect can be obtained.

  Here, when the first lens group has at least one predetermined lens, it is possible to suppress variations in spherical aberration, astigmatism, axial chromatic aberration, and lateral chromatic aberration that occur in the first lens group during zooming. Thus, it is possible to obtain a variable power optical system with higher resolution over the entire variable power range. At this time, it is more preferable that the predetermined lens has a negative refractive power. When the predetermined lens has a negative refractive power, it is possible to better suppress the change in lateral chromatic aberration, particularly the change in secondary chromatic aberration, which occurs in the first lens group, and to achieve a higher zooming power variation over the entire zooming range. An optical system can be obtained.

  Further, when the second lens group has at least one predetermined lens, it is possible to suppress each variation of spherical aberration, astigmatism, axial chromatic aberration, and lateral chromatic aberration that occurs in the second lens group at the time of zooming, A variable power optical system with higher resolution over the entire variable power range can be obtained. At this time, it is more preferable that the predetermined lens has a negative refractive power. When the predetermined lens has a negative refractive power, it is possible to better suppress spherical aberration fluctuations and astigmatism fluctuations generated in the second lens group, and the zooming optical system has a higher resolution over the entire zooming range. A system can be obtained.

  In addition, when the subsequent lens group has at least one predetermined lens, it is possible to suppress variations in spherical aberration, astigmatism, axial chromatic aberration, and lateral chromatic aberration that occur in the subsequent lens group during zooming. A variable power optical system with higher resolution can be obtained over the entire region. At this time, it is more preferable that the predetermined lens has a negative refractive power. When the predetermined lens has a negative refractive power, it is possible to better suppress spherical aberration fluctuations and astigmatism fluctuations generated in the second lens group, and the zooming optical system has a higher resolution over the entire zooming range. A system can be obtained.

1-2-3. Conditional expression (3)
Conditional expression (3) defines the ratio of the focal length of the second lens group to the focal length of the entire variable magnification optical system at the wide angle end. By satisfying conditional expression (3), it is possible to reduce the size even when a high zoom ratio is realized, and it is possible to obtain a zoom lens with high optical performance.

  On the other hand, when the numerical value of conditional expression (3) is equal to or greater than the upper limit value, the refractive power of the second lens group is small, and when the zoom ratio is increased, the total length of the entire zoom optical system becomes long, It becomes difficult to reduce the size of the variable magnification optical system. On the other hand, if the numerical value of the conditional expression (3) is less than or equal to the lower limit value, the refractive power of the second lens group becomes too large, and it becomes difficult to correct astigmatism and field curvature.

  In obtaining these effects, the upper limit value of conditional expression (3) is preferably 1.44, and more preferably 1.43. The smaller the upper limit of conditional expression (3), the easier it is to reduce the size of the zoom optical system even when a high zoom ratio is realized. On the other hand, the lower limit value of conditional expression (3) is preferably 0.75, and more preferably 0.8. As the lower limit of conditional expression (3) is larger, better optical performance can be obtained over the entire zoom range.

1-2-4. Conditional expression (4)
Conditional expression (4) defines the ratio of the focal length of the first lens unit to the focal length of the entire variable power optical system at the telephoto end. By satisfying conditional expression (4), it is possible to reduce the size even when a high zoom ratio is realized, and it is possible to obtain a zoom optical system with high optical performance.

  On the other hand, when the numerical value of conditional expression (4) exceeds the upper limit, the refractive power of the first lens group is small, and the total optical length of the entire zooming optical system becomes long when the zooming ratio is increased. Therefore, it is difficult to reduce the size of the variable magnification optical system. On the other hand, if the numerical value of the conditional expression (4) is less than or equal to the lower limit value, the refractive power of the first lens group becomes too large, and it becomes difficult to correct spherical aberration and chromatic aberration.

  In obtaining these effects, the upper limit value of conditional expression (4) is preferably 0.38, and more preferably 0.35. The smaller the upper limit of conditional expression (4), the lower the total optical length of the entire variable magnification optical system, even when a high zoom ratio is realized, and it is easy to obtain a small variable magnification optical system. become. On the other hand, the lower limit value of conditional expression (4) is preferably 0.12, and more preferably 0.15. As the lower limit of conditional expression (4) is larger, better optical performance can be obtained over the entire zoom range.

1-2-5. Conditional expression (5)
It is preferable that the variable magnification optical system satisfies the following conditional expression (5).

(5) 0.3 <TTL / Ft <0.8
However,
TTL is the total length of the entire variable magnification optical system at the telephoto end.

  Conditional expression (5) defines the ratio between the total length of the entire variable magnification optical system and the focal length of the variable magnification optical system at the telephoto end. By satisfying conditional expression (5), it is possible to reduce the size in the full length direction even when a high zoom ratio is realized. Further, by satisfying conditional expression (5), it is possible to satisfactorily correct field curvature and axial chromatic aberration, and to realize good optical performance over the entire zoom range.

  If the numerical value of conditional expression (5) exceeds the upper limit, the total length of the variable magnification optical system becomes long when a variable magnification optical system with a high variable magnification ratio is used. Therefore, a compact variable magnification optical system is realized. It becomes difficult to do. On the other hand, when the numerical value of the conditional expression (5) is less than or equal to the lower limit value, it becomes difficult to correct curvature of field and axial chromatic aberration, and it becomes difficult to maintain good optical performance over the entire zoom range.

  In obtaining these effects, the upper limit value of conditional expression (5) is preferably 0.78, and more preferably 0.75. The smaller the upper limit of conditional expression (5), the easier it is to reduce the size of the zoom optical system even when a high zoom ratio is realized. On the other hand, the lower limit value of conditional expression (5) is preferably 0.35, and more preferably 0.40. The larger the lower limit of conditional expression (5), the easier it is to correct field curvature and axial chromatic aberration, and it becomes easier to maintain good optical performance over the entire zoom range.

2. Next, an imaging apparatus according to the present invention will be described. The imaging apparatus according to the present invention converts the optical image formed by the variable magnification optical system according to the present invention and the variable magnification optical system provided on the image plane side of the variable magnification optical system into an electrical signal. And an image pickup device.

  Here, there is no limitation in particular in an image pick-up element etc., Solid-state image pick-up elements, such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor, etc. can be used. The imaging device according to the present invention is suitable for an imaging device using these solid-state imaging devices such as a digital camera and a video camera. Further, the imaging device may be a lens-fixed imaging device in which a lens is fixed to a housing, or may be a lens-exchangeable imaging device such as a single-lens reflex camera or a mirrorless single-lens camera. Of course.

  A specific configuration example is shown in FIG. FIG. 37 is a diagram schematically showing a cross section of the lens-interchangeable image pickup apparatus 1. As shown in FIG. 37, in the interchangeable lens imaging device 1, a lens barrel portion 2 containing a variable magnification optical system is detachably fixed to a mount portion 3 of the imaging device 1. The imaging device 1 includes the imaging element 4 on the image side of the variable magnification optical system, and an optical image is formed on the imaging surface of the imaging element 4 by the variable magnification optical system. The optical image formed on the imaging surface is converted into an electrical signal in the imaging element 4. Image data generated based on the electrical signal is output to an image output device such as a back monitor 5 provided on the back surface of the imaging device 1.

  The zoom optical system according to the present invention has a high resolving power and high optical performance over the entire zoom range. Further, the zoom optical system can be made compact while realizing a high zoom ratio. Therefore, a subject image with a clear outline can be obtained even when the number of pixels of the image sensor 4 is high and the sensitivity is high. For this reason, the imaging apparatus including the variable magnification optical system according to the present invention is suitable for an application in which a part of the image is enlarged and the details of the subject need to be confirmed, such as a monitoring imaging apparatus.

  In the present invention, the variable power optical system means a variable focus lens having a variable focal length such as a zoom lens or a varifocal lens.

  Next, an Example is shown and this invention is demonstrated concretely. However, the present invention is not limited to the following examples. The optical system of each example given below is an imaging optical system used for an imaging device (optical device) such as a digital camera, a video camera, a silver salt film camera, and in particular, an installation type of a monitoring imaging device or the like. It can be preferably applied to an imaging device. In each lens cross-sectional view, the left side is the object side and the right side is the image plane side in the drawing.

(1) Configuration of Optical System FIG. 1 shows the lens configuration of the zoom lens, which is the optical system of Embodiment 1 according to the present invention, in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele). Indicates. In the drawing, the locus of each lens unit at the time of zooming is indicated by an arrow.

  The zoom lens of Example 1 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 having negative refractive power, the fifth lens group G5 having positive refractive power, the sixth lens group G6 having negative refractive power, and the seventh lens group having positive refractive power And G7. A specific lens configuration is as shown in FIG. In Example 1, a lens having a negative refractive power that constitutes a cemented lens disposed closest to the object side in the first lens group G1, and a negative refraction disposed closest to the object side in the second lens group G2. A lens having negative refracting power that constitutes the fourth lens group G4, and a lens having negative refracting power that constitutes the cemented lens that constitutes the fifth lens group, respectively. (See Table 1).

  In FIG. 1, “CG” is a parallel flat plate having no substantial refractive power, such as a cover glass. “I” is an image plane, and specifically represents an imaging plane of a solid-state imaging device such as a CCD sensor or a CMOS sensor, or a film plane of a silver salt film. Since these points are the same in the lens cross-sectional views shown in the other embodiments, the description thereof will be omitted below.

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. Fixed in the axial direction, the fourth lens group G4 is moved to the image side, the fifth lens group G5 is moved along a locus convex to the object side, the sixth lens group G6 is moved to the object side, and the seventh lens group G7 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis. The seventh lens group G7 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 1 shows surface data of the zoom lens. In Table 1, “surface number” is the order of the lens surfaces counted from the object side, “r” is the radius of curvature of the lens surfaces, “d” is the distance on the optical axis of the lens surfaces, and “nd” is the d-line (wavelength The refractive index for “λ = 587.56 nm”, “νd”, indicates the Abbe number for the d-line. An asterisk “*” added next to the surface number indicates that the lens surface is aspherical, and “S” indicates an aperture stop. D (7) and the like indicate that the interval on the optical axis of the lens surface is a variable interval that changes at the time of zooming.

  Table 2 shows the aspheric data. The aspheric surface data indicates the conical coefficient and the aspheric coefficient of each order when the aspheric surface is defined by the following equation.

z = ch ² / [1+ {1- (1 + k) c ² h ² } ^1/2 + A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰ ...
Where c is the curvature (1 / r), h is the height from the optical axis, k is the conic coefficient, A4, A6, A8, A10... Are the aspheric coefficients of the respective orders.

  Table 3 shows various data. The various data indicate various data at the wide-angle end, the intermediate focal position, and the telephoto end. In the table, “F” is the focal length (mm) when the zoom lens is focused at infinity, “Fno.” Is the F number of the zoom lens, and “ω” is the half angle of view (°) of the optical system. , D (7), etc. indicate variable intervals between the lens surfaces. Table 4 shows the focal length of each lens group.

  Table 37 shows numerical values of the conditional expressions (3) to (5) for the zoom lens. Since the items related to these tables are the same in the tables shown in other examples, the description thereof will be omitted below.

  2 to 4 are longitudinal aberration diagrams at the time of focusing at infinity at the wide angle end, the intermediate focal position, and the telephoto end of the zoom lens according to the first embodiment. The longitudinal aberration diagrams shown in the drawings are spherical aberration (mm), astigmatism (mm), and distortion (%), respectively, in order from the left side in the drawing.

  In the spherical aberration diagram, the vertical axis represents the F number (indicated by FNO in the figure), the solid line is the d line (wavelength 587.56 nm), the alternate long and short dash line is the C line (wavelength 656.27 nm), and the broken line is the F line (wavelength 486.13 nm). ).

  In the astigmatism diagram, the vertical axis represents the half angle of view (ω), the solid line is the characteristic in the sagittal image plane (ds) for the d-line (wavelength 587.56 nm), and the dotted line is the characteristic in the meridional image plane (dm) for the d-line. .

  In the distortion diagram, the vertical axis represents the half angle of view (ω) and the characteristic at the d-line (wavelength 587.56 nm).

  Since the matters relating to these longitudinal aberration diagrams are the same in the longitudinal aberration diagrams shown in the other examples, the description thereof will be omitted below.

(1) Configuration of Optical System FIG. 5 shows the lens configuration of the zoom lens, which is the optical system of Example 2 according to the present invention, in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele). Indicates.

  The zoom lens of Example 2 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 having negative refractive power, the fifth lens group G5 having positive refractive power, the sixth lens group G6 having negative refractive power, and the seventh lens group having positive refractive power And G7. A specific lens configuration is as shown in FIG. In Example 2, a lens having a negative refractive power constituting a cemented lens disposed closest to the object side in the first lens group G1, and a negative refraction disposed closest to the object side in the second lens group G2. The lens having power and the lens having negative refractive power constituting the cemented lens constituting the fifth lens group G5 are the predetermined lenses referred to in the present invention (see Table 5).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. Fixed in the axial direction, the fourth lens group G4 is moved to the image side, the fifth lens group G5 is moved along a locus convex to the object side, the sixth lens group G6 is moved to the object side, and the seventh lens group G7 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis. The second lens group G2 is configured to be movable in a direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 5 shows surface data of the zoom lens, and Tables 6 to 8 show aspheric data, various data, and focal lengths of the lens groups. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 6 to 8 are longitudinal aberration diagrams at the time of focusing at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state of the zoom lens.

(1) Configuration of Optical System FIG. 9 shows a zoom lens that is a variable magnification optical system of Example 3 according to the present invention in the wide-angle end state (Wide), the intermediate focal position state (Mid), and the telephoto end state (Tele). A lens structure is shown.

  The zoom lens of Example 3 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a negative refractive power, the fifth lens group G5 has a positive refractive power, and the sixth lens group G6 has a negative refractive power. A specific lens configuration is as shown in FIG. In Example 3, a lens having a negative refractive power constituting a cemented lens disposed closest to the object side in the first lens group G1, and a negative refraction disposed closest to the object side in the second lens group G2. A lens having a negative refractive power disposed on the most object side in the sixth lens group G6, and a lens having a negative refractive power constituting a cemented lens constituting the fifth lens group G5, respectively. This is a predetermined lens according to the present invention (see Table 9).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. The fourth lens group G4 is moved toward the image side, the fifth lens group G5 is moved along a convex locus toward the object side, and the sixth lens group G6 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4 and the fifth lens group G5 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis. The sixth lens group G6 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 9 shows surface data of the zoom lens, and Tables 10 to 12 show aspheric data, various data, and the focal length of each lens group. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 10 to 12 are longitudinal aberration diagrams at the time of focusing at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state of the zoom lens.

(1) Configuration of Optical System FIG. 13 shows the lens configuration of the zoom lens that is the optical system of Embodiment 4 in the wide-angle end state (Wide), the intermediate focal position state (Mid), and the telephoto end state (Tele).

  The zoom lens of Example 4 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG.

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. Fixed in the axial direction, the fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is moved to the image side. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis. The sixth lens group G6 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the zoom lens are applied will be described. Table 13 shows surface data of the zoom lens, and Tables 14 to 16 show aspheric data, various data, and the focal length of each lens group. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 14 to 16 show longitudinal aberration diagrams when the zoom lens is focused at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state.

(1) Configuration of Optical System FIG. 17 shows a lens configuration in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele) of the zoom lens that is the optical system of Example 5 according to the present invention. Indicates.

  The zoom lens of Example 5 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG. In Example 5, the lens having negative refractive power constituting the cemented lens disposed closest to the object side in the first lens group G1 is the predetermined lens according to the present invention (see Table 17).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. Fixed in the axial direction, the fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is moved to the image side. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 17 shows surface data of the zoom lens, and Tables 18 to 20 show aspheric data, various data, and the focal length of each lens group. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 18 to 20 are longitudinal aberration diagrams at the time of focusing at infinity in the wide-angle end state, the intermediate focusing position state, and the telephoto end state of the zoom lens.

(1) Configuration of Optical System FIG. 21 shows the lens configuration in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele) of the zoom lens that is the optical system of Example 6 according to the present invention. Indicates.

  The zoom lens of Example 6 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG. In Example 6, the lens having negative refractive power constituting the cemented lens disposed closest to the object side in the first lens group G1 is the predetermined lens according to the present invention (see Table 21).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. Fixed in the axial direction, the fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is moved to the image side. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fifth lens group G5 to the object side along the optical axis.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 21 shows surface data of the zoom lens, and Tables 22 to 24 show aspheric data, various data, and focal lengths of the lens groups. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 22 to 24 show longitudinal aberration diagrams when the zoom lens is focused at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state.

(1) Configuration of Optical System FIG. 25 shows a lens configuration in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele) of the zoom lens that is the optical system of Example 7 according to the present invention. Indicates.

  The zoom lens of Example 7 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG. In Example 7, a lens having a negative refractive power that constitutes a cemented lens disposed closest to the object side in the first lens group G1, and a negative refraction disposed closest to the object side in the second lens group G2. A lens having a negative refracting power, a lens having a negative refractive power disposed closest to the image side in the second lens group G2, and a cemented lens disposed closest to the image side in the fourth lens group G4. Each lens is a predetermined lens according to the present invention (see Table 25).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. The fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4 and the fifth lens group G5 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fourth lens group G4 to the object side along the optical axis. The fifth lens group G5 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 25 shows surface data of the zoom lens, and Tables 26 to 28 show aspheric data, various data, and focal lengths of the respective lens groups. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 26 to 29 are longitudinal aberration diagrams at the time of focusing at infinity in the wide-angle end state, the intermediate focusing position state, and the telephoto end state of the zoom lens.

(1) Configuration of Optical System FIG. 29 shows the lens configuration in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele) of the zoom lens that is the optical system of Example 8 according to the present invention. Indicates.

  The zoom lens of Example 8 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG. In Example 8, a lens having a negative refractive power that constitutes a cemented lens arranged closest to the object side in the first lens group G1, and a negative refraction arranged closest to the object side in the second lens group G2. Lens having negative refractive power, constituting a lens having negative refractive power arranged closest to the image side in the second lens group, and a cemented lens arranged closest to image side in the fourth lens group G4 Each of the lenses having negative refractive power constituting the cemented lens of the fifth lens group G5 is a predetermined lens according to the present invention (see Table 29).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. The fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group G3, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4 and the fifth lens group G5 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fourth lens group G4 to the object side along the optical axis. The fifth lens group G5 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 29 shows surface data of the zoom lens, and Tables 30 to 32 show aspheric data, various data, and focal lengths of the respective lens groups. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 30 to 32 show longitudinal aberration diagrams when the zoom lens is focused at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state.

(1) Configuration of Optical System FIG. 33 shows a lens configuration in the wide-angle end state (Wide), intermediate focus position state (Mid), and telephoto end state (Tele) of the zoom lens that is the optical system of Example 9 according to the present invention. Indicates.

  The zoom lens of Example 9 includes a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power in order from the object side. The fourth lens group G4 has a positive refractive power, the fifth lens group G5 has a negative refractive power, and the sixth lens group G6 has a positive refractive power. A specific lens configuration is as shown in FIG. In Example 9, in the first lens group G1, a lens having a negative refractive power that constitutes a cemented lens disposed closest to the object side, and in the second lens group G2, negative refraction disposed closest to the object side. A lens having a negative refractive power arranged closest to the image side in the second lens group G2, a lens having a negative refractive power arranged closest to the image side in the third lens group G3, and a fourth lens. A lens having a negative refractive power constituting the cemented lens disposed closest to the image side in the group G4, a lens having a negative refractive power on the image side of the cemented lens constituting the fifth lens group G5, and a sixth lens group G6 The lenses having negative refractive power arranged on the most object side in FIG. 3 are the predetermined lenses according to the present invention (see Table 33).

  In the zoom lens, at the time of zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed in the optical axis direction, the second lens group G2 is moved to the image side, and the third lens group G3 is moved to the light side. The fourth lens group G4 is moved to the object side, the fifth lens group G5 is moved to the object side, and the sixth lens group G6 is fixed in the optical axis direction. The aperture stop S is disposed on the object side of the third lens group, and the aperture stop S is fixed in the optical axis direction together with the third lens group G3 during zooming. The second lens group G2 is a variator, and the fourth lens group G4 and the fifth lens group G5 each function as a compensator.

  In the zoom lens, when focusing from an object at infinity to an object at a short distance, focusing is performed by moving the fourth lens group G4 to the object side along the optical axis. The fifth lens group G5 is configured to be movable in the direction perpendicular to the optical axis, and functions as an anti-vibration lens group VC that corrects image blur during imaging.

(2) Numerical Examples Next, numerical examples to which specific numerical values of the optical system are applied will be described. Table 33 shows surface data of the zoom lens, and Tables 34 to 36 show aspheric data, various data, and focal lengths of the respective lens groups. Table 37 shows numerical values of the conditional expressions (3) to (5) of the optical system. Further, FIGS. 34 to 36 show longitudinal aberration diagrams at the time of focusing at infinity in the wide-angle end state, the intermediate focus position state, and the telephoto end state of the zoom lens.

  According to the present invention, it is possible to provide a small zooming optical system and an imaging apparatus that have a high zooming ratio and good optical performance over the entire zooming range.

G1 ... 1st lens group G2 ... 2nd lens group G3 ... 3rd lens group G4 ... 4th lens group G5 ... 5th lens group G6 ... 6th lens group G7 .. Seventh lens group S... Aperture stop I... Image plane F... Focusing group VC .. Anti-vibration group 1. ... Mount 4 ... Image sensor 5 ... Back monitor

Claims (11)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a subsequent lens having a positive refractive power as a whole, which are arranged in order from the object side. Composed of groups and
At the time of zooming from the wide-angle end to the telephoto end, at least the distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is decreased. Moving the second lens group;
A variable power optical system having at least one predetermined lens that satisfies the following conditional expressions (1) and (2) and satisfying the following conditional expressions (3) and (4): system.
(1) 1.93 <nd
(2) 23.0 <vd
(3) 0.7 <| F2 / Fw | <1.45
(4) 0.1 <F1 / Ft <0.4
However,
nd is a refractive index with respect to the d-line (wavelength 587.6 nm) of the predetermined lens;
vd is an Abbe number with respect to the d-line (wavelength 587.6 nm) of the predetermined lens;
F1 is a focal length of the first lens group,
F2 is a focal length of the second lens group,
Fw is the focal length of the entire variable magnification optical system at the wide angle end,
Ft is the focal length of the entire variable magnification optical system at the telephoto end.   2. The zoom optical system according to claim 1, wherein the first lens unit is fixed in the optical axis direction and the second lens unit is moved to the image side during zooming from the wide-angle end to the telephoto end.   The zoom optical system according to claim 1, wherein the first lens group includes at least one of the predetermined lenses.   The zoom optical system according to any one of claims 1 to 3, wherein the second lens group includes at least one of the predetermined lenses.   The zoom optical system according to any one of claims 1 to 4, wherein the subsequent lens group includes at least one of the predetermined lenses.   The variable power optical system according to any one of claims 1 to 5, wherein the predetermined lens has a negative refractive power. The zoom optical system according to any one of claims 1 to 6, wherein the following conditional expression (5) is satisfied.
(5) 0.3 <TTL / Ft <0.8
However,
TTL is the total length of the entire variable magnification optical system at the telephoto end.   The variable magnification optical system according to any one of claims 1 to 7, wherein focusing from an infinite distance to a short distance object is performed by moving all or a part of the subsequent lens group.   The subsequent lens group includes a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a positive refractive power, which are arranged in order from the object side. The zoom lens system according to any one of claims 1 to 8.   The subsequent lens group includes a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens group having a negative refractive power, which are arranged in order from the object side. The zoom lens system according to any one of claims 1 to 8.   11. A variable magnification optical system according to any one of claims 1 to 10, and imaging that converts an optical image formed by the variable magnification optical system on the image side of the variable magnification optical system into an electrical signal. An imaging apparatus comprising: an element.

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