Zoom lens and image pickup apparatus
阅读说明：本技术 变焦镜头及摄像装置 (Zoom lens and image pickup apparatus ) 是由 永见亮介 于 2021-05-21 设计创作，主要内容包括：本发明提供一种具有防振性能、有利于小型化及轻量化、保持良好的光学性能的变焦镜头及具备该变焦镜头的摄像装置。变焦镜头从最靠物体侧朝向像侧依次具备具有正屈光力的第1透镜组、具有负屈光力的第2透镜组、具有正屈光力的中间组及具有负屈光力的后续组。变倍时第1透镜组移动。第2透镜组从物体侧朝向像侧依次包括图像抖动校正时不动的第2透镜组前组和图像抖动校正时移动的具有负屈光力的防振组。变焦镜头满足预先确定的条件式。(The invention provides a zoom lens having vibration-proof performance, which is beneficial to miniaturization and light weight and keeps good optical performance, and an image pickup device with the zoom lens. The zoom lens includes, in order from the most object side toward the image side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, an intermediate group having positive refractive power, and a subsequent group having negative refractive power. The 1 st lens group moves at the time of magnification change. The 2 nd lens group includes, in order from the object side toward the image side, a 2 nd lens group front group that is not moved at the time of image shake correction and a vibration prevention group having negative refractive power that moves at the time of image shake correction. The zoom lens satisfies a predetermined conditional expression.)
1. A zoom lens includes, in order from the most object side toward the image side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power disposed continuously with the 1 st lens group, an intermediate group having positive refractive power including at least one lens group, and a subsequent group having negative refractive power including at least one lens group,
when zooming, the 1 st lens group moves along the optical axis, the interval between the 1 st lens group and the 2 nd lens group changes, the interval between the 2 nd lens group and the intermediate group changes, and the interval between the intermediate group and the subsequent group changes,
the 2 nd lens group includes, in order from the object side toward the image side, a 2 nd lens group front group fixed at the time of image shake correction and an anti-vibration group having negative refractive power moving in a direction intersecting with the optical axis at the time of image shake correction,
a difference in an optical axis direction between a position of the 1 st lens group at a telephoto end and a position of the 1 st lens group at a wide-angle end is set to DL1,
Lw, where is an optical axis distance from a lens surface closest to the object side of the entire system at the wide-angle end to a lens surface closest to the image side of the entire system at the wide-angle end,
The lateral magnification of the vibration-proof set at the telephoto end in a state of focusing on an object at infinity is set to be beta ist,
When the combined lateral magnification of all lenses on the image side of the anti-vibration group at the telephoto end in the state of focusing on an object at infinity is β irt,
the zoom lens satisfies the following conditional expressions (1) and (2),
0.4＜DL1/Lw＜1 (1)
3.5＜|(1-βist)×βisrt|＜7 (2)。
2. the zoom lens according to claim 1,
the intermediate group includes an intermediate group A having a positive refractive power and an intermediate group B having a positive refractive power in order from the object side toward the image side,
when the magnification is changed, the interval between the middle group A and the middle group B is changed.
3. The zoom lens according to claim 2,
only the middle B group moves along the optical axis in focus.
4. The zoom lens according to claim 3,
the focal length of the intermediate group A is fmA,
With the focal length of the middle B group set to fmB,
the zoom lens satisfies the following conditional expression (3),
0.5＜fmA/fmB＜2 (3)。
5. the zoom lens according to claim 3 or 4,
the distance on the optical axis between the intermediate group A and the intermediate group B at the telephoto end in the state of focusing on an infinite object is DmaB,
With the focal length of the middle B group set to fmB,
the zoom lens satisfies the following conditional expression (4),
0.3＜DmAB/fmB＜1 (4)。
6. the zoom lens according to claim 3 or 4,
the lateral magnification of the intermediate B group at the telephoto end in a state of focusing on an object at infinity is set to be β mBt,
When the combined lateral magnification of all the lenses on the image side of the intermediate B group at the telephoto end in the state of focusing on an object at infinity is mBrt,
the zoom lens satisfies the following conditional expression (5),
3＜|(1-βmBt2)×βmBrt2|＜10 (5)。
7. the zoom lens according to any one of claims 1 to 4,
the distance on the optical axis from the most object side lens surface of the entire system at the telephoto end to the most object side lens surface of the anti-vibration group at the telephoto end is Llist,
In the case where the focal length of the 1 st lens group is set to f1,
the zoom lens satisfies the following conditional expression (6),
0.57＜Llist/f1＜0.7 (6)。
8. the zoom lens according to any one of claims 1 to 4,
the front group of the 2 nd lens group has positive refractive power.
9. The zoom lens according to any one of claims 1 to 4,
the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is set to fw,
In case the focal length of the anti-vibration group is set to fis,
the zoom lens satisfies the following conditional expression (7),
1＜fw/|fis|＜5 (7)。
10. the zoom lens according to any one of claims 1 to 4,
the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is set to fw,
In the case where the focal length of the intermediate group at the wide-angle end in a state of focusing on an infinite object is set to fmw,
the zoom lens satisfies the following conditional expression (8),
1＜fw/fmw＜5 (8)。
11. the zoom lens according to any one of claims 1 to 4,
the focal length of the entire system at the telephoto end in the state of focusing on an object at infinity is ft,
In the case where the focal length of the intermediate group at the telephoto end in the state of being focused on the object at infinity is set to fmt,
the zoom lens satisfies the following conditional expression (9),
5＜ft/fmt＜10 (9)。
12. the zoom lens according to any one of claims 1 to 4,
the focal length of the intermediate group at the telephoto end in a state of being focused on an object at infinity is set to fmt,
In the case where the focal length of the intermediate group at the wide-angle end in a state of focusing on an infinite object is set to fmw,
the zoom lens satisfies the following conditional expression (10),
0.8＜fmt/fmw＜1.8 (10)。
13. the zoom lens according to any one of claims 1 to 4,
the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is set to fw,
In the case where the focal length of the lens group having the strongest negative refractive power in the subsequent group is set to fsmax,
the zoom lens satisfies the following conditional expression (11),
1＜fw/|fsmax|＜4 (11)。
14. the zoom lens according to any one of claims 1 to 4,
the subsequent group includes, in order from the object side toward the image side, a lens group having a negative refractive power and a lens group having a positive refractive power,
when zooming, the interval between the lens group with negative refractive power and the lens group with positive refractive power is changed.
15. The zoom lens according to any one of claims 1 to 4,
a stop is disposed between the 2 nd lens group and the intermediate group.
16. The zoom lens according to any one of claims 1 to 4,
the focal length of the entire system at the telephoto end in the state of focusing on an object at infinity is ft,
In the case where the focal length of the entire system at the wide-angle end in a state of focusing on an infinite object is set to fw,
the zoom lens satisfies the following conditional expression (12),
3＜ft/fw＜5 (12)。
17. the zoom lens according to any one of claims 1 to 4,
in the case where the focal length of the entire system at the wide-angle end in a state of focusing on an infinite object is set to fw,
the zoom lens satisfies the following conditional expression (13),
1.3＜Lw/fw＜1.6 (13)。
18. the zoom lens according to any one of claims 1 to 4,
the back focal length of the air converted distance meter of the whole system at the wide-angle end in a state of focusing on an object at infinity was Bfw,
In the case where the focal length of the entire system at the wide-angle end in a state of focusing on an infinite object is set to fw,
the zoom lens satisfies the following conditional expression (14),
0.35＜Bfw/fw＜0.55 (14)。
19. the zoom lens according to any one of claims 1 to 4,
the subsequent group includes a lens group fixed relative to the image plane at the most image side in zooming.
20. The zoom lens according to any one of claims 1 to 4,
the curvature radius of the most image side lens surface of the 1 st lens group is R1R,
When the radius of curvature of the most object-side lens surface in the 2 nd lens group is R2f,
the zoom lens satisfies the following conditional expression (15),
0.8＜(R1r+R2f)/(R1r-R2f)＜4 (15) 。
21. an image pickup device provided with the zoom lens according to any one of claims 1 to 20.
Technical Field
The present technology relates to a zoom lens and an imaging device.
Background
As a zoom lens applicable to an image pickup apparatus such as a digital camera and a video camera, lens systems described in patent document 1 and patent document 2 are known.
Patent document 1: japanese patent laid-open publication No. 2019-053122
Patent document 2: japanese patent laid-open publication No. 2015-191008
In recent years, a zoom lens having vibration-proof performance, a small and lightweight configuration, and excellent optical performance is required.
Disclosure of Invention
The present invention has been made in view of the above circumstances, and an object thereof is to provide a zoom lens having vibration-proof performance, which is advantageous for downsizing and weight reduction, and which maintains excellent optical performance, and an image pickup apparatus including the zoom lens.
The zoom lens of the present invention includes, in order from the most object side toward the image side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power disposed continuously from the 1 st lens group, an intermediate group having positive refractive power including at least one lens group, and a subsequent group having negative refractive power including at least one lens group, wherein the 1 st lens group moves along the optical axis at the time of magnification change, an interval between the 1 st lens group and the 2 nd lens group changes, an interval between the 2 nd lens group and the intermediate group changes, an interval between the intermediate group and the subsequent group changes, the 2 nd lens group includes, in order from the object side toward the image side, a 2 nd lens group front group fixed at the time of image shake correction and an anti-vibration group having negative refractive power moving in a direction intersecting the optical axis at the time of image shake correction, and a difference in the optical axis direction between a position of the 1 st lens group at the telephoto end and a position of the 1 st lens group at the wide-angle end is set to DL1, When the distance on the optical axis from the lens surface closest to the object side of the entire system at the wide-angle end to the lens surface closest to the image side of the entire system at the wide-angle end is represented by Lw, the lateral magnification of the vibration-proof group at the telephoto end in the state of focusing on an object at infinity is represented by ist, and the combined lateral magnification of all the lenses at the telephoto end in the state of focusing on an object at infinity and on the image side of the vibration-proof group is represented by irt,
the zoom lens satisfies the following conditional expressions (1) and (2),
0.4＜DL1/Lw＜1 (1)，
3.5＜|(1-βist)×βisrt|＜7 (2)。
the intermediate group may include an intermediate a group having positive refractive power and an intermediate B group having positive refractive power in order from the object side toward the image side, and the interval between the intermediate a group and the intermediate B group may change during magnification change. In this case, it is preferable that only the middle B group is moved along the optical axis during focusing.
In the configuration in which only the intermediate group B moves along the optical axis in focusing, when the focal length of the intermediate group a is fmA and the focal length of the intermediate group B is fmB,
the zoom lens preferably satisfies the following conditional expression (3),
0.5＜fmA/fmB＜2 (3)。
in a configuration in which only the middle group B moves along the optical axis during focusing, when the interval on the optical axis between the middle group A and the middle group B at the telephoto end in a state of focusing on an object at infinity is set to DmaB, and the focal length of the middle group B is set to fmB,
the zoom lens preferably satisfies the following conditional expression (4),
0.3＜DmAB/fmB＜1 (4)。
in the configuration in which only the middle B group moves along the optical axis during focusing, when the lateral magnification of the middle B group at the telephoto end in the state of focusing on the object at infinity is β mBt, and the combined lateral magnification of all the lenses on the image side of the middle B group at the telephoto end in the state of focusing on the object at infinity is β mBrt,
the zoom lens preferably satisfies the following conditional expression (5),
3＜|(1-mBt2)×βmBrt2|＜10 (5)。
when the distance on the optical axis from the most object side lens surface of the entire system at the telephoto end to the most object side lens surface of the vibration-proof group at the telephoto end is Llist, and the focal length of the 1 st lens group is f1,
the zoom lens preferably satisfies the following conditional expression (6),
0.57＜Llist/f1＜0.7 (6)。
preferably, the front group of lens group 2 has positive refractive power.
In the case where the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is set to fw and the focal length of the vibration prevention set is set to fis,
the zoom lens preferably satisfies the following conditional expression (7),
1＜fw/|fis|＜5 (7)。
in the case where the focal length of the entire system at the wide-angle end in a state of focusing on an infinite object is set to fw and the focal length of the intermediate group at the wide-angle end in a state of focusing on an infinite object is set to fmw,
the zoom lens preferably satisfies the following conditional expression (8),
1＜fw/fmw＜5 (8)。
in the case where the focal length of the entire system at the telephoto end in the state of focusing on the infinity object is set to ft and the focal length of the intermediate group at the telephoto end in the state of focusing on the infinity object is set to fmt,
the zoom lens preferably satisfies the following conditional expression (9),
5＜ft/fmt＜10 (9)。
in the case where the focal length of the middle group at the telephoto end in the state of focusing on the infinity object is set to fmt and the focal length of the middle group at the wide-angle end in the state of focusing on the infinity object is set to fmw,
the zoom lens preferably satisfies the following conditional expression (10),
0.8＜fmt/fmw＜1.8 (10)。
in the case where the focal length of the entire system at the wide-angle end in a state of focusing on an infinitely distant object is set to fw and the focal length of the lens group having the strongest negative refractive power in the subsequent group is set to fsmax,
the zoom lens preferably satisfies the following conditional expression (11),
1＜fw/|fsmax|＜4 (11)。
preferably, the subsequent group includes, in order from the object side toward the image side, a lens group having negative refractive power and a lens group having positive refractive power, and an interval between the lens group having negative refractive power and the lens group having positive refractive power changes when magnification is changed.
Preferably, a stop is disposed between the 2 nd lens group and the intermediate group.
In the case where ft is the focal length of the entire system at the telephoto end in the state of focusing on the object at infinity, and fw is the focal length of the entire system at the wide-angle end in the state of focusing on the object at infinity,
the zoom lens preferably satisfies the following conditional expression (12),
3＜ft/fw＜5 (12)。
when the distance on the optical axis from the lens surface closest to the object side of the entire system at the wide-angle end to the lens surface closest to the image side of the entire system at the wide-angle end is represented by Lw, and the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is represented by fw,
the zoom lens preferably satisfies the following conditional expression (13),
1.3＜Lw/fw＜1.6 (13)。
when the back focal length of the air converted distance meter of the entire system at the wide-angle end in a state of focusing on an object at infinity is Bfw and the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is fw,
the zoom lens preferably satisfies the following conditional expression (14),
0.35＜Bfw/fw＜0.55 (14)。
preferably, the subsequent group includes a lens group fixed with respect to the image plane at the most image side when the magnification is changed.
The imaging device of the present invention includes the zoom lens of the present invention.
In addition, the term "including" or "including" in the present specification means that the optical elements other than a lens having substantially no refractive power and a lens such as a diaphragm, a filter, and a cover glass, and mechanical parts such as a lens flange, a lens barrel, an imaging element, and a hand-shake correction mechanism, and the like, may be included in addition to the components described above.
In the present specification, "group having positive refractive power" means that the group as a whole has positive refractive power. Similarly, "group having negative refractive power" means that the group as a whole has negative refractive power. "lens having positive refractive power" and "positive lens" have the same meaning. "lens having negative refractive power" and "negative lens" have the same meaning. The "lens group" is not limited to a configuration including a plurality of lenses, and may be a configuration including only one lens.
A compound aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical lens are integrally formed to function as one aspherical lens as a whole) is used as one lens and is not regarded as a cemented lens. Unless otherwise specified, the sign and surface shape of the refractive power of the lens including the aspherical surface are considered in the paraxial region.
In this specification, "entire system" means a zoom lens. The "back focal length of the air-converted distance meter" is an air-converted distance on the optical axis from the lens surface closest to the image side to the image surface of the entire system in a state of focusing on an object at infinity. The "focal length" used in the conditional expression is a paraxial focal length. The value used in the conditional expression is a value based on the d-line in a state of focusing on an object at infinity. The "d line", "C line", "F line" and "g line" described in this specification are bright lines. In this specification, the wavelength of d-line is considered to be 587.56nm (nanometers), the wavelength of C-line is considered to be 656.27nm (nanometers), the wavelength of F-line is considered to be 486.13nm (nanometers), and the wavelength of g-line is considered to be 435.84nm (nanometers).
Effects of the invention
According to the present invention, it is possible to provide a zoom lens having vibration-proof performance, which is advantageous for downsizing and weight reduction, and which maintains excellent optical performance, and an image pickup apparatus including the zoom lens.
Drawings
Fig. 1is a sectional view and a moving direction showing the structure of a zoom lens system according to embodiment 1.
Fig. 2 is a cross-sectional view showing the configuration and light beams in each zoom state of the zoom lens of embodiment 1.
Fig. 3 is each aberration diagram of the zoom lens of embodiment 1.
Fig. 4 is a sectional view and a moving direction showing the structure of the zoom lens of embodiment 2.
Fig. 5 is each aberration diagram of the zoom lens of embodiment 2.
Fig. 6 is a sectional view and a moving direction showing the structure of the zoom lens of embodiment 3.
Fig. 7 is each aberration diagram of the zoom lens of embodiment 3.
Fig. 8 is a sectional view and a moving direction showing the structure of the zoom lens of embodiment 4.
Fig. 9 is each aberration diagram of the zoom lens of embodiment 4.
Fig. 10 is a sectional view and a moving direction showing the structure of a zoom lens of embodiment 5.
Fig. 11 is each aberration diagram of the zoom lens of embodiment 5.
Fig. 12 is a front perspective view of the imaging device according to the embodiment.
Fig. 13 is a perspective view of the back side of the imaging device according to the embodiment.
Detailed Description
Hereinafter, embodiments of the present invention will be described. A zoom lens according to an embodiment of the present invention includes, in order from the most object side toward the image side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power disposed continuously from the 1 st lens group, an intermediate group having positive refractive power including at least one lens group, and a subsequent group having negative refractive power including at least one lens group. When zooming from a wide angle end to a telephoto end, the 1 st lens group moves along an optical axis, an interval between the 1 st lens group and the 2 nd lens group varies, an interval between the 2 nd lens group and an intermediate group varies, and an interval between the intermediate group and a subsequent group varies. With this configuration, it is easy to realize magnification variation from the wide-angle end to the telephoto end, to make the configuration compact even in the state of magnification variation, and to suppress aberration variation accompanying magnification variation.
In addition, the "lens group" in the present specification refers to a constituent part of a zoom lens including at least one lens separated by an air space that changes when magnification is changed.
In the magnification variation, the lens groups are moved or fixed in units of a lens group, and the mutual interval of the lenses within one lens group is not changed.
The 2 nd lens group includes, in order from the object side toward the image side, a 2 nd lens group front group fixed at the time of image shake correction and a vibration-proof group having negative refractive power moving in a direction intersecting with the optical axis at the time of image shake correction. By setting only a part of the 2 nd lens group as the vibration prevention group instead of setting the entire 2 nd lens group as the vibration prevention group, it is possible to make the entire 2 nd lens group and the vibration prevention group have refractive powers different from each other. This facilitates control of the refractive power of the vibration control unit, and is advantageous in ensuring good vibration control performance and downsizing the vibration control unit.
Preferably, the front group of lens group 2 has positive refractive power. In this case, the diameter of the light beam incident on the vibration isolation group can be reduced, which is advantageous for reducing the diameter of the vibration isolation unit. Further, when the front group of the 2 nd lens group has positive refractive power, the negative refractive power of the vibration-proof group is easily strengthened, and therefore, it is advantageous to shorten the moving amount of the vibration-proof group at the time of image blur correction.
The intermediate group may include an intermediate a group having positive refractive power and an intermediate B group having positive refractive power in order from the object side toward the image side, and the interval between the intermediate a group and the intermediate B group may change during magnification change. In this case, the intermediate a group and the intermediate B group can be assigned to the positive refractive power of the intermediate group, and therefore, it is advantageous to suppress variation in spherical aberration at the time of magnification change.
When the intermediate group includes the intermediate a group and the intermediate B group, it is preferable that only the intermediate B group is moved along the optical axis in focusing. Hereinafter, a group that moves in focus is referred to as a focus group. When the intermediate B group is set as the focus group, the focus group is located adjacent to the image side of the intermediate a group having positive refractive power, and therefore, it is advantageous to reduce the diameter of the focus group.
Next, a preferred structure of the conditional expression will be described. However, the conditional expressions that the zoom lens of the present invention preferably satisfies are not limited to the conditional expressions described as the expressions, and include all conditional expressions in which the lower limit and the upper limit are arbitrarily combined from the preferable and more preferable conditional expressions. In the following description of a preferred structure and a structure that can be achieved, the zoom lens of the present invention is also referred to as a zoom lens.
When the difference in the optical axis direction between the position of the 1 st lens group at the telephoto end and the position of the 1 st lens group at the wide-angle end is DL1, and the distance in the optical axis from the most object-side lens surface of the entire system at the wide-angle end to the most image-side lens surface of the entire system at the wide-angle end is Lw, the zoom lens preferably satisfies the following conditional expression (1). By not setting the corresponding value of the conditional expression (1) to the lower limit or less, the moving amount of the 1 st lens group at the time of magnification change does not become excessively small, which is advantageous for a high magnification change ratio. By not setting the corresponding value of the conditional expression (1) to be equal to or more than the upper limit, the moving amount of the 1 st lens group at the time of magnification change does not become excessively large, and therefore, the total length is favorably shortened, and the diameter and the weight are favorably reduced. Satisfying the conditional expression (1) is advantageous for a compact and lightweight structure and a high zoom ratio. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (1-1).
0.4＜DL1/Lw＜1 (1)
0.5＜DL1/Lw＜0.85 (1-1)
When the lateral magnification of the vibration-proof group at the telephoto end in the state of focusing on the infinity object is β ist, and the combined lateral magnification of all the lenses on the image side of the vibration-proof group at the telephoto end in the state of focusing on the infinity object is β isrt, the zoom lens preferably satisfies the following conditional expression (2). By not setting the corresponding value of the conditional expression (2) to the lower limit or less, the amount of movement of the anti-vibration group in image shake correction does not become excessively large, which is advantageous for downsizing. By not setting the corresponding value of the conditional expression (2) to be equal to or greater than the upper limit, the positional accuracy of the vibration prevention group at the time of image shake correction does not become excessively sensitive, and therefore control is easy. Satisfying the conditional expression (2) is advantageous for downsizing the vibration isolation unit and ensuring proper vibration isolation performance. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (2-1).
3.5＜|(1-βist)×βisrt|＜7 (2)
3.5＜|(1-βist)×βisrt|＜5.5 (2-1)
In the configuration in which the intermediate group includes the intermediate a group and the intermediate B group described above and the focus group includes the intermediate B group, the zoom lens preferably satisfies the following conditional expression (3) when the focal length of the intermediate a group is fmA and the focal length of the intermediate B group is fmB. By not setting the corresponding value of conditional expression (3) to the lower limit or less, the amount of movement of the focus group in focusing does not become excessively large, and therefore, the total length is advantageously shortened. By not setting the correspondence value of conditional expression (3) to be equal to or greater than the upper limit, it is advantageous to suppress variation in spherical aberration during focusing. Satisfying the conditional expression (3) is advantageous for shortening the total length and suppressing spherical aberration. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (3-1).
0.5＜fmA/fmB＜2 (3)
0.8＜fmA/fmB＜1.2 (3-1)
In the configuration in which the intermediate group includes the intermediate a group and the intermediate B group described above and the focus group includes the intermediate B group, the zoom lens preferably satisfies the following conditional expression (4) when an interval on the optical axis between the intermediate a group and the intermediate B group at the telephoto end in a state of being focused on an infinite object is DmAB, and a focal length of the intermediate B group is fmB. By not setting the corresponding value of conditional expression (4) to the lower limit or less, DmAB is not excessively narrowed compared to the refractive power of the intermediate group B, and therefore, it is advantageous for close-range photography. By not setting the corresponding value of conditional expression (4) to be equal to or greater than the upper limit, DmAB does not become excessively wide compared to the refractive power of the intermediate group B, and hence it is advantageous for downsizing. Satisfying the conditional expression (4) is advantageous for shortening the shortest imaging distance and for downsizing. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (4-1).
0.3＜DmAB/fmB＜1 (4)
0.35＜DmAB/fmB＜0.7 (4-1)
In the configuration in which the intermediate group includes the intermediate a group and the intermediate B group and the focus group includes the intermediate B group, the zoom lens preferably satisfies the following conditional expression (5) when the lateral magnification of the intermediate B group at the telephoto end in the state focused on the infinity object is mB t and the combined lateral magnification of all the lenses on the image side of the intermediate B group at the telephoto end in the state focused on the infinity object is β mBrt. By not setting the correspondence value of conditional expression (5) to the lower limit or less, the amount of movement of the focus group when focusing on the short distance side does not become excessively large, which is advantageous for downsizing. By not setting the correspondence value of the conditional expression (5) to the upper limit or more, the positional accuracy of the focus group at the time of focusing does not become excessively sensitive, and therefore control is easy. Satisfying the conditional expression (5) is advantageous for downsizing the focus unit and shortening the shortest photographing distance. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (5-1).
3＜|(1-βmBt2)×βmBrt2|＜10 (5)
5＜|(1-βmBt2)×βmBrt2|＜7 (5-1)
When L1ist is an optical axis distance from a most object side lens surface of the entire system at the telephoto end to a most object side lens surface of the vibration-proof group at the telephoto end, and f 1is a focal length of the 1 st lens group, the zoom lens preferably satisfies the following conditional expression (6). By not setting the corresponding value of conditional expression (6) to the lower limit or less, the refractive power of the 1 st lens group does not become excessively weak, and therefore, the diameter of the light flux incident on the vibration isolation group particularly at the telephoto end can be reduced, which is advantageous for reducing the diameter of the vibration isolation unit. By not setting the correspondence value of the conditional expression (6) to be equal to or more than the upper limit, it is advantageous to shorten the total length or to easily correct each aberration, particularly spherical aberration, in the entire system. Satisfying the conditional expression (6) is advantageous for miniaturization and aberration correction. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (6-1).
0.57＜Llist/f1＜0.7 (6)
0.58＜Llist/f1＜0.67 (6-1)
When the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is fw and the focal length of the vibration-proof group is fis, the zoom lens preferably satisfies the following conditional expression (7). By not setting the corresponding value of conditional expression (7) to the lower limit or less, the amount of movement of the anti-vibration group in image shake correction does not become excessively large, which is advantageous for downsizing. By not setting the corresponding value of the conditional expression (7) to be equal to or greater than the upper limit, the positional accuracy of the vibration prevention group at the time of image shake correction does not become excessively sensitive, and therefore control is easy. Satisfying the conditional expression (7) is advantageous for downsizing the vibration isolation unit and ensuring proper vibration isolation performance. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (7-1).
1＜fw/fis|＜5 (7)
2＜fw/fis|＜4 (7-1)
When the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is fw and the focal length of the intermediate group at the wide-angle end in a state of focusing on an object at infinity is fmw, the zoom lens preferably satisfies the following conditional expression (8). By not setting the correspondence value of conditional expression (8) to the lower limit or less, the increase in the diameter of the light beam incident on the subsequent group can be suppressed, which is advantageous for the decrease in the diameter. By not setting the corresponding value of conditional expression (8) to be equal to or greater than the upper limit, aberration variation at the time of magnification variation can be easily suppressed. Satisfying the conditional expression (8) is advantageous for reducing the diameter and suppressing the aberration variation at the time of magnification change. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (8-1).
1＜fw/fmw＜5 (8)
2＜fw/fmw＜3.5 (8-1)
When the focal length of the entire system at the telephoto end in the state of focusing on the object at infinity is ft and the focal length of the intermediate group at the telephoto end in the state of focusing on the object at infinity is fmt, the zoom lens preferably satisfies the following conditional expression (9). By not setting the correspondence value of conditional expression (9) to the lower limit or less, the increase in the diameter of the light beam incident on the subsequent group can be suppressed, which is advantageous for the decrease in the diameter. By not setting the corresponding value of the conditional expression (9) to be equal to or more than the upper limit, aberration variation at the time of magnification variation can be easily suppressed. Satisfying the conditional expression (9) is advantageous for reducing the diameter and suppressing the aberration variation at the time of magnification change. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (9-1).
5＜ft/fmt＜10 (9)
6.5＜ft/fmt＜8.5 (9-1)
When the focal length of the intermediate group at the wide-angle end in a state focused on the infinity object is fmw and the focal length of the intermediate group at the telephoto end in a state focused on the infinity object is fmt, the zoom lens preferably satisfies the following conditional expression (10). By not setting the correspondence value of the conditional expression (10) to the lower limit or less, it is advantageous to suppress aberration variation on the telephoto side at the time of magnification variation.
By not setting the correspondence value of the conditional expression (10) to be equal to or greater than the upper limit, it is advantageous to suppress aberration variation on the wide angle side at the time of magnification variation. Satisfying the conditional expression (10) is advantageous in suppressing aberration variation at the time of magnification variation. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (10-1).
0.8＜fmt/fmw＜1.8 (10)
1.1＜fmt/fmw＜1.7 (10-1)
When the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is fw and the focal length of the lens group having the strongest negative refractive power in the subsequent group is fsmax, the zoom lens preferably satisfies the following conditional expression (11). The corresponding value of the conditional expression (11) is not lower than the lower limit, which is advantageous for high zoom ratio. By not setting the correspondence value of the conditional expression (11) to be equal to or more than the upper limit, it is advantageous to suppress aberration variation, particularly variation in astigmatism, at the time of magnification variation. Satisfying the conditional expression (11) is advantageous for high zoom ratio and suppression of aberration variation during zooming. In particular, in the case where the lens group having the strongest negative refractive power in the subsequent group is a lens group that moves at the time of magnification change, the above-described effect can be remarkably obtained. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (11-1).
1＜fw/|fsmax|＜4 (11)
2＜fw/|fsmax|＜3.5 (11-1)
When the focal length of the entire system at the telephoto end in a state of focusing on the object at infinity is ft and the focal length of the entire system at the wide-angle end in a state of focusing on the object at infinity is fw, the zoom lens preferably satisfies the following conditional expression (12). By not setting the corresponding value of the conditional expression (12) to be equal to or less than the lower limit, the zoom ratio suitable for the zoom lens can be easily secured. By not making the corresponding value of the conditional expression (12) equal to or more than the upper limit, downsizing is facilitated. Satisfying the conditional expression (12) is advantageous for a compact configuration and ensures an appropriate zoom ratio. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (12-1).
3＜ft/fw＜5 (12)
3.9＜ft/fw＜4.2 (12-1)
When the distance on the optical axis from the lens surface closest to the object side of the entire system at the wide-angle end to the lens surface closest to the image side of the entire system at the wide-angle end is represented by Lw, and the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is represented by fw, the zoom lens preferably satisfies the following conditional expression (13). By not setting the correspondence value of conditional expression (13) to the lower limit or less, it is advantageous to suppress field curvature. By not making the corresponding value of conditional expression (13) equal to or more than the upper limit, the total length is favorably shortened, which is also favorable for weight reduction. Satisfying the conditional expression (13) contributes to the suppression of field curvature, the reduction in size, and the reduction in weight. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (13-1).
1.3＜Lw/fw＜1.6 (13)
1.35＜Lw/fw＜1.55 (13-1)
When the back focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is Bfw in terms of air converted distance, and the focal length of the entire system at the wide-angle end in a state of focusing on an object at infinity is fw, the zoom lens preferably satisfies the following conditional expression (14). By not setting the corresponding value of the conditional expression (14) to the lower limit or less, the outer diameter of the lens on the image side can be suppressed from increasing, which is advantageous for downsizing and weight reduction. By not making the corresponding value of conditional expression (14) equal to or greater than the upper limit, it is advantageous to correct chromatic aberration of magnification, and it is possible to shorten the total length, which is advantageous to weight reduction. Satisfying the conditional expression (14) contributes to correction of chromatic aberration of magnification, reduction in size, and weight reduction. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (14-1).
0.35＜Bfw/fw＜0.55 (14)
0.35＜Bfw/fw＜0.48 (14-1)
When the radius of curvature of the most image side lens surface of the 1 st lens group is R1R and the radius of curvature of the most object side lens surface of the 2 nd lens group is R2f, the zoom lens preferably satisfies the following conditional expression (15). Satisfying the conditional expression (15) is advantageous in suppressing variation in spherical aberration at the time of magnification variation, and thereby easily reducing the burden of aberration correction of other lens groups. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (15-1).
0.8＜(R1r+R2f)/(R1r-R2f)＜4 (15)
1.2＜(R1r+R2f)/(R1r-R2f)＜2.5 (15-1)
When the lateral magnification of the anti-vibration group at the wide-angle end in a state of focusing on the object at infinity is β isw, and the combined lateral magnification of all lenses on the image side of the anti-vibration group at the wide-angle end in a state of focusing on the object at infinity is β isrw, the zoom lens preferably satisfies the following conditional expression (16). By not setting the corresponding value of the conditional expression (16) to the lower limit or less, the amount of movement of the anti-vibration group in image shake correction does not become excessively large, which is advantageous for downsizing. By not setting the corresponding value of the conditional expression (16) to be equal to or greater than the upper limit, the positional accuracy of the vibration prevention group at the time of image shake correction is not excessively sensitive, and therefore control is easy. Satisfying the conditional expression (16) is advantageous for downsizing the vibration isolation unit and ensuring proper vibration isolation performance. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (16-1).
1＜|(1-βisw)×β isrw|＜5 (16)
1.75＜|(1-βisw)×βisrw|＜3 (16-1)
In the configuration in which the intermediate group includes the intermediate a group and the intermediate B group and the focus group includes the intermediate B group, it is preferable that the zoom lens satisfies the following conditional expression (17) when a lateral magnification of the intermediate B group at the wide-angle end in a state focused on an infinite object is β mBw and a combined lateral magnification of all lenses on the image side of the intermediate B group at the wide-angle end in a state focused on an infinite object is β mbbw. By not setting the correspondence value of conditional expression (17) to the lower limit or less, the amount of movement of the focus group when focusing on the short distance side does not become excessively large, which is advantageous for downsizing.
By not setting the correspondence value of the conditional expression (17) to be equal to or greater than the upper limit, the positional accuracy of the focus group at the time of focusing is not excessively sensitive, and therefore control is easy. Satisfying the conditional expression (17) is advantageous for downsizing the focus unit and shortening the shortest photographing distance. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (17-1).
1＜|(1-βmBw2)×βmBrw2|＜10 (17)
3＜|(1-βmBw2)×βmBrw2|＜5 (17-1)
When the focal length of the entire system at the wide-angle end in a state of focusing on an infinitely distant object is set to fw and the focal length of the 1 st lens group is set to f1, the zoom lens preferably satisfies the following conditional expression (18). By not setting the corresponding value of the conditional expression (18) to the lower limit or less, the increase in the diameter of the light flux incident on the 2 nd lens group can be suppressed, which contributes to the miniaturization of the entire system. By not setting the correspondence value of the conditional expression (18) to be equal to or more than the upper limit, it is easy to correct each aberration, particularly spherical aberration, in the entire system. Satisfying the conditional expression (18) is advantageous for downsizing and correction of each aberration. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (18-1).
0.3＜fw/f1＜0.8 (18)
0.4＜fw/f1＜0.7 (18-1)
When the focal length of the entire system at the telephoto end in a state of focusing on an object at infinity is ft and the focal length of the 1 st lens group is f1, the zoom lens preferably satisfies the following conditional expression (19). By not setting the corresponding value of the conditional expression (19) to the lower limit or less, the increase in the diameter of the light flux incident on the 2 nd lens group can be suppressed, which contributes to the miniaturization of the entire system. By not setting the correspondence value of the conditional expression (19) to be equal to or more than the upper limit, it is easy to correct each aberration, particularly spherical aberration, in the entire system. Satisfying the conditional expression (19) is advantageous for downsizing and correction of each aberration. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (19-1).
1.7＜ft/f1＜3 (19)
1.8＜ft/f1＜2.7 (19-1)
When the focal length of the entire system at the telephoto end in a state of focusing on an object at infinity is ft and the focal length of the 2 nd lens group is f2, the zoom lens preferably satisfies the following conditional expression (20). The corresponding value of the conditional expression (20) is not lower than the lower limit, which is advantageous for high zoom ratio. By not setting the correspondence value of the conditional expression (20) to be equal to or greater than the upper limit, it is possible to suppress an increase in the diameter of the light beam incident on the intermediate group, which is advantageous for downsizing the entire system. Satisfying the conditional expression (20) is advantageous for high zoom ratio and miniaturization. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (20-1).
7＜ft/f2|＜15 (20)
8＜ft/f2|＜14 (20-1)
When the focal length of the intermediate group at the wide-angle end in a state of focusing on an object at infinity is fmw and the focal length of the 2 nd lens group is f2, the zoom lens preferably satisfies the following conditional expression (21). By not setting the corresponding value of conditional expression (21) to the lower limit or less, the negative refractive power of the 2 nd lens group does not become excessively weak, and therefore, it is advantageous for high magnification ratio. By not setting the corresponding value of the conditional expression (21) to be equal to or greater than the upper limit, the negative refractive power of the 2 nd lens group does not become excessively strong, and therefore, the increase in the diameter of the light flux incident on the intermediate group and the group on the image side of the intermediate group can be suppressed, which is advantageous for downsizing. Satisfying the conditional expression (21) is advantageous for high zoom ratio and miniaturization. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (21-1).
0.8＜fmw/|f2|＜1.3 (21)
0.85＜fmw/|r2|＜1.1 (21-1)
When the focal length of the intermediate group at the telephoto end in the state of being focused on the infinity object is fmt and the focal length of the 2 nd lens group is f2, the zoom lens preferably satisfies the following conditional expression (22). By not setting the corresponding value of conditional expression (22) to the lower limit or less, the negative refractive power of the 2 nd lens group does not become excessively weak, and therefore, it is advantageous for high magnification ratio. By not setting the corresponding value of the conditional expression (22) to be equal to or greater than the upper limit, the negative refractive power of the 2 nd lens group does not become excessively strong, and therefore, the increase in the diameter of the light flux incident on the intermediate group and the group on the image side of the intermediate group can be suppressed, which is advantageous for downsizing. Satisfying the conditional expression (22) is advantageous for high zoom ratio and miniaturization. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (22-1).
0.9＜fmt/|f2|＜2 (22)
1＜fmt/|f2|＜1.8 (22-1)
When the intermediate group includes at least one positive lens and the d-line reference abbe number of the positive lens of the intermediate group is represented by v mp, the intermediate group preferably includes at least one positive lens satisfying the following conditional expression (23). By not setting the corresponding value of conditional expression (23) to the lower limit or less, it is advantageous to correct the on-axis chromatic aberration on the telephoto side. By not setting the corresponding value of conditional expression (23) to be equal to or higher than the upper limit, the refractive index of the positive lens can be prevented from becoming too low. This makes it possible to easily secure refractive power without making the absolute value of the curvature radius of the lens surface extremely small, and to prevent the lens from becoming large in the optical axis direction, which is advantageous in reducing the size and weight of the intermediate group. Satisfying the conditional expression (23) is advantageous for correction of axial chromatic aberration, reduction in size, and weight reduction. In order to obtain more favorable characteristics, the intermediate group more preferably includes at least one positive lens satisfying the following conditional expression (23-1).
70＜v mp＜100 (23)
80＜v mp＜96 (23-1)
In the configuration in which the 2 nd lens group front group has positive refractive power, when the d-line reference dispersion coefficient of the positive lens of the 2 nd lens group front group is v 2p, the 2 nd lens group front group preferably includes at least one positive lens satisfying the following conditional expression (24). By not setting the corresponding value of the conditional expression (24) to the lower limit or less, it is advantageous to correct the on-axis chromatic aberration on the telephoto side. By not setting the corresponding value of the conditional expression (24) to be equal to or higher than the upper limit, the refractive index of the positive lens can be prevented from becoming too low. This makes it possible to easily secure refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and to prevent the lens from becoming large in the optical axis direction, which is advantageous for the size and weight reduction of the front group of the 2 nd lens group. Satisfying the conditional expression (24) is advantageous for correction of axial chromatic aberration, reduction in size, and weight reduction. In order to obtain more favorable characteristics, the 2 nd lens group front group more preferably includes at least one positive lens satisfying the following conditional expression (24-1).
50＜v 2p＜90 (24)
65＜v 2p＜85 (24-1)
When the radius of curvature of the most object-side lens surface of the 1 st lens group is R1f and the radius of curvature of the most image-side lens surface of the 1 st lens group is R1R, the zoom lens preferably satisfies the following conditional expression (25). By satisfying the conditional expression (25), it is advantageous to correct spherical aberration, and thus it is easy to reduce the burden of aberration correction of other lens groups. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (25-1).
-6＜(R1f+R1r)/(R1f-R1r)＜-1 (25)
-5＜(R1f+R1r)/(R1f-R1r)＜-2 (25-1)
When the average value of the d-line reference dispersion coefficients of all the positive lenses of the 1 st lens group is v ave1p, the zoom lens preferably satisfies the following conditional expression (26). By not setting the corresponding value of the conditional expression (26) to the lower limit or less, it is advantageous to correct the on-axis chromatic aberration on the telephoto side. By not setting the corresponding value of the conditional expression (26) to be equal to or higher than the upper limit, the refractive index of the positive lens can be prevented from becoming too low. Accordingly, it is not necessary to make the absolute value of the curvature radius of the lens surface extremely small, and it is easy to secure the refractive power, and it is possible to prevent the lens from becoming large in the optical axis direction, which is advantageous for the miniaturization and weight reduction of the 1 st lens group. Satisfying the conditional expression (26) is advantageous for correction of axial chromatic aberration, reduction in size, and weight reduction. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (26-1).
65＜v ave1p＜85 (26)
70＜v ave1p＜80 (26-1)
When the average value of the d-line reference dispersion coefficients of all the negative lenses of the 2 nd lens group is v ave2n, the zoom lens preferably satisfies the following conditional expression (27). The correction of chromatic aberration is facilitated by not lowering the correspondence value of conditional expression (27) to the lower limit or less. By not setting the corresponding value of the conditional expression (27) to be equal to or higher than the upper limit, the refractive index of the negative lens can be prevented from becoming too low. This makes it possible to easily ensure refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and to prevent the volume of the lens from increasing, which contributes to weight reduction of the vibration isolation unit. Satisfying the conditional expression (27) contributes to correction of chromatic aberration and weight reduction. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (27-1).
30＜v ave2n＜60 (27)
35＜v ave2n＜52 (27-1)
In the configuration in which the intermediate group includes the intermediate a group and the intermediate B group, it is preferable that the zoom lens satisfies the following conditional expression (28) when an average value of d-line-reference dispersion coefficients of all the positive lenses of the intermediate a group is v avemAp. By not setting the corresponding value of the conditional expression (28) to the lower limit or less, it is advantageous to correct the on-axis chromatic aberration on the telephoto side. By not setting the corresponding value of the conditional expression (28) to be equal to or higher than the upper limit, the refractive index of the positive lens can be prevented from becoming too low. This makes it possible to easily secure refractive power without making the absolute value of the curvature radius of the lens surface extremely small, and to prevent the lens from becoming large in the optical axis direction, which is advantageous in reducing the size and weight of the intermediate group. Satisfying the conditional expression (28) is advantageous for correction of axial chromatic aberration, reduction in size, and weight reduction. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (28-1).
60＜v avemAp＜85 (28)
67＜v avemAp＜80 (28-1)
When the vibration-proof group includes at least one positive lens and the d-line reference abbe number of the positive lens of the vibration-proof group is v isp, the vibration-proof group preferably includes at least one positive lens satisfying the following conditional expression (29). Satisfying the conditional expression (29) is advantageous for suppressing variation in chromatic aberration of magnification at the time of image shake correction. In order to obtain more favorable characteristics, the vibration prevention set more preferably includes at least one positive lens satisfying the following conditional expression (29-1).
15＜v isp＜40 (29)
20＜v isp＜33 (29-1)
When the focal length of the entire system at the wide-angle end in a state of focusing on an infinitely distant object is set to fw and the focal length of the 2 nd lens group is set to f2, the zoom lens preferably satisfies the following conditional expression (30). By not setting the corresponding value of conditional expression (30) to the lower limit or less, the negative refractive power of the 2 nd lens group does not become excessively weak, and therefore, it is advantageous for high magnification ratio. By not setting the corresponding value of the conditional expression (30) to be equal to or greater than the upper limit, the negative refractive power of the 2 nd lens group does not become excessively strong, and therefore, the diameter of the light flux incident on the intermediate group and the group on the image side of the intermediate group can be suppressed from increasing, which is advantageous for downsizing. Satisfying the conditional expression (30) is advantageous for high zoom ratio and miniaturization. In order to obtain more favorable characteristics, the zoom lens more preferably satisfies the following conditional expression (30-1).
1＜fw/|f2|＜5 (30)
2＜fw/|f2|＜3.5 (30-1)
Specifically, each group may have the following structure, for example.
The 1 st lens group may be configured to include one negative lens and two positive lenses. In this case, it is advantageous to correct chromatic aberration on the axis, and to reduce the weight as compared with the case where the 1 st lens group includes four or more lenses.
For example, the 1 st lens group may be configured to include, in order from the object side toward the image side, a cemented lens formed by a single negative lens and a single positive lens cemented together, and a single positive lens. More specifically, the 1 st lens group may be configured to include, in order from the object side to the image side, a negative meniscus lens with a convex surface facing the object side, a double convex lens, and a positive meniscus lens with a convex surface facing the object side.
The number of lenses constituting the front group of the 2 nd lens group is preferably three or less. In this case, the entire system can be advantageously downsized and lightened.
The 2 nd lens group front group may be configured to include only one piece of positive lens, or may be configured to include a cemented lens in which one piece of positive lens and one piece of negative lens are cemented.
Preferably, the vibration-proof set includes two negative lenses and one positive lens. In this case, it is advantageous to suppress performance degradation caused by variation in chromatic aberration at the time of image shake correction. Further, in the case where the vibration-proof group includes two negative lenses and one positive lens, chromatic aberration is easily corrected as compared with the case where the vibration-proof group includes two or less lenses, and it is advantageous to reduce the size and weight of the vibration-proof unit as compared with the case where the vibration-proof group includes four or more lenses.
Preferably, the vibration isolation group includes a cemented lens in which a negative lens and a positive lens are cemented in this order from the object side, or a cemented lens in which a positive lens and a negative lens are cemented in this order from the object side. In this case, it is advantageous to reduce deterioration of optical performance caused by assembly error.
For example, the vibration prevention group may include a cemented lens formed by a single negative lens and a single positive lens cemented together, and a single negative lens in order from the object side to the image side. More specifically, the vibration prevention group may include, in order from the object side to the image side, a cemented lens formed by a negative lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side cemented together, and a negative lens having a concave surface facing the object side.
Preferably, an aperture stop is disposed between the 2 nd lens group and the intermediate group. In this case, the anti-vibration group and the aperture stop are close to each other, and therefore, the diameter reduction of the anti-vibration group is facilitated.
Preferably the intermediate group comprises less than 2 lens groups. In this case, the reduction in size and weight is facilitated. For example, the intermediate group a may include 1 lens group, and the intermediate group B may include 1 lens group.
The subsequent group may be constituted to include 2 lens groups whose mutual intervals are changed at the time of varying magnification. For example, the subsequent group may include a lens group having a negative refractive power and a lens group having a positive refractive power in order from the object side toward the image side, and the interval between the lens group having a negative refractive power and the lens group having a positive refractive power may change during magnification change. In this case, the lens group having negative refractive power can tilt the light beam in a direction away from the optical axis Z, and the lens group having positive refractive power can reduce the angle formed by the light beam and the optical axis Z, which is advantageous for reducing the incident angle of the principal ray of the off-axis light flux incident on the image plane while securing a large image circle.
Preferably, the lens group having the largest absolute value of dioptric power in the subsequent group comprises at least one positive lens and at least one negative lens. In this case, it is advantageous to correct astigmatism and chromatic aberration of magnification and to suppress aberration variation at the time of magnification variation.
The zoom lens may be configured such that all lens groups move at the time of magnification variation, or may be configured to include a lens group fixed with respect to the image plane at the time of magnification variation. For example, the subsequent group may be configured to include a lens group that is fixed with respect to the image surface when the magnification is varied, at the most image side. In this case, the lens group fixed at the time of magnification change closest to the image side can provide an effect of suppressing variation in chromatic aberration of magnification at the time of magnification change. The 2 nd lens group may be fixed to the image plane at the time of magnification change. In this case, it is advantageous to reduce the deterioration of the optical performance due to the error and to further simplify the apparatus, and therefore, it is advantageous to reduce the size and weight of the apparatus.
The above-described preferred configurations and realizable configurations may be arbitrarily combined, including configurations relating to conditional expressions, and are preferably selectively adopted as appropriate in accordance with the required specifications.
As an example, a preferable embodiment of the zoom lens of the present invention is a zoom lens including, in order from the most object side toward the image side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power disposed continuously from the 1 st lens group, an intermediate group having positive refractive power including at least one lens group, and a subsequent group having negative refractive power including at least one lens group, wherein, at the time of magnification change, the 1 st lens group moves along the optical axis, an interval between the 1 st lens group and the 2 nd lens group changes, an interval between the 2 nd lens group and the intermediate group changes, an interval between the intermediate group and the subsequent group changes, and the 2 nd lens group includes, in order from the object side toward the image side, a 2 nd lens group front group fixed at the time of image shake correction and an anti-vibration group having negative refractive power moving in a direction intersecting with the optical axis at the time of image shake correction, the zoom lens satisfies the conditional expressions (1) and (2). According to the zoom lens of the preferred embodiment, the zoom lens has vibration-proof performance, and is advantageous for downsizing and weight reduction, and good optical performance is easily maintained.
Next, an embodiment of a zoom lens of the present invention will be described with reference to the drawings.
[ example 1]
A cross-sectional view illustrating a structure at the wide-angle end of a zoom lens of embodiment 1 of the present invention is shown in fig. 1. Fig. 2 shows a cross-sectional view of the structure and light beam in each zoom state of the zoom lens. Fig. 1 and 2 show a state of focusing on an object at infinity, with the left side being the object side and the right side being the image side. In fig. 2, the WIDE-angle end state is shown in the upper stage labeled "WIDE", the intermediate focal length state is shown in the MIDDLE stage labeled "MIDDLE", and the telephoto end state is shown in the lower stage labeled "TELE". Fig. 2 shows, as luminous fluxes, an on-axis luminous flux wa and a luminous flux wb at the maximum viewing angle in the wide-angle end state, an on-axis luminous flux ma and a luminous flux mb at the maximum viewing angle in the intermediate focal length state, and an on-axis luminous flux ta and a luminous flux tb at the maximum viewing angle in the telephoto end state. Fig. 2 shows, as an example, Lw, DL1, and Llist used in the above conditional expression.
The zoom lens according to embodiment 1 includes, in order from the object side toward the image side along the optical axis Z, a 1 st lens group G1, a 2 nd lens group G2, an aperture stop, a 3 rd lens group G3, a 4 th lens group G4, a 5 th lens group G5, and a 6 th lens group G6. In the zoom lens, upon varying magnification from the wide angle end to the telephoto end, five lens groups of 1 lens group G1 to 5 lens group G5 move along the optical axis Z while changing the interval of adjacent lens groups in the optical axis direction, the 6 th lens group G6 is fixed with respect to the image plane Sim, and the aperture stop St moves integrally with the 3 rd lens group G3. Below each lens group in fig. 1, a schematic moving direction of the lens group moving at the time of magnification variation from the wide-angle end to the telephoto end is shown by a single arrow, and a ground mark is shown for the lens group fixed at the time of magnification variation. In the zoom lens according to embodiment 1, the intermediate group includes the 3 rd lens group G3 and the 4 th lens group G4, and the subsequent group includes the 5 th lens group G5 and the 6 th lens group G6.
The 1 st lens group G1 includes three lenses L11 to L13 in order from the object side to the image side. The 2 nd lens group G2 includes four lenses L21 to L24 in order from the object side to the image side. The 3 rd lens group G3 includes three lenses L31 to L33 in order from the object side to the image side. The 4 th lens group G4 includes three lenses L41 to L43 in order from the object side to the image side. The 5 th lens group G5 includes two lenses, lenses L51 to L52, in order from the object side to the image side. The 6 th lens group G6 includes one lens of lens L61. The vibration isolation group includes three lenses L22 to L24. The focusing group includes a 4 th lens group G4. In fig. 1, a double arrow in the vertical direction is shown below the vibration prevention group, and a double arrow in the horizontal direction is shown below the focus group.
Fig. 1 and 2 show an example in which the zoom lens is applied to an image pickup apparatus, and the optical member PP having a parallel flat plate shape is disposed between the zoom lens and the image plane Sim. The optical member PP is a member assumed to be various filters, cover glass, or the like. Examples of the various filters include a low-pass filter, an infrared cut filter, and a filter for cutting off a specific wavelength region. The optical member PP has no optical power, and may be omitted.
The zoom lens of embodiment 1 has basic lens data shown in table 1, specifications and variable surface distances shown in table 2, and aspherical surface coefficients shown in table 3. In table 1, the column Sn shows the surface number when the surface closest to the object side is the 1 st surface and the number increases one by one toward the image side, the column R shows the radius of curvature of each surface, the column D shows the surface interval on the optical axis between each surface and the surface adjacent to the image side, the column Nd shows the refractive index of each component with respect to the D-line, and the column v D shows the D-line-based dispersion coefficient of each component.
In table 1, the sign of the radius of curvature of the surface of the shape in which the convex surface faces the object side is positive, and the sign of the radius of curvature of the surface of the shape in which the convex surface faces the image side is negative. The aperture stop St and the optical component PP are also shown in table 1. The term (St) is described in the area number column corresponding to the area of the aperture stop St together with the area number. The value in the lowermost column of D in table 1is the distance between the image plane Sim and the surface closest to the image side in the table. In table 1, the variable surface interval at the time of magnification is denoted by DD [ ], and the object-side surface number of the interval is denoted by [ ]andis shown in the column D.
Table 2 shows zoom magnification Zr, focal length F, open F value fno, maximum full view angle 2 ω, and variable surface interval at the time of zooming. The (°) column 2 ω represents units of degrees. In table 2, the respective values of the WIDE-angle end state, the intermediate focal length state, and the telephoto end state are shown in the columns described as WIDE, MIDDLE, TELE, respectively. The values shown in tables 1 and 2 are values based on the d-line in a state of focusing on an object at infinity.
In table 1, the aspheric surface is denoted by a symbol, and the column of the curvature radius of the aspheric surface shows the numerical value of the paraxial curvature radius. In table 3, the column Sn shows the surface number of the aspheric surface, and the columns KA and Am (m is 3, 4, 5, and … … 10) show the numerical values of the aspheric surface coefficients of the aspheric surfaces.
"E. + -. n" (n: integer) of numerical values of aspherical surface coefficients of Table 3 represents ". times.10±n". KA and Am are aspheric coefficients in an aspheric expression represented by the following expression.
Zd＝C×h2/{1+(1-KA×C2×h2)1/2}+∑Am×hm
Wherein the content of the first and second substances,
and (d) is as follows: aspheric depth (length of a perpendicular line that depends from a point on the aspheric surface of height h to a plane tangent to the aspheric vertex and perpendicular to the optical axis);
h: height (distance from the optical axis to the lens surface);
c: the reciprocal of the paraxial radius of curvature;
KA. Am, and (2): the coefficient of the aspherical surface is,
the aspherical Σ represents a sum associated with m.
In the data of each table, degrees are used as a unit of angle, mm (millimeter) is used as a unit of length, and the optical system can be used in an enlarged scale or in a reduced scale. In each table shown below, numerical values rounded to a predetermined number of digits are shown.
[ Table 1]
Example 1
Sn
R
D
Nd
v d
1
206.29219
2.000
1.91082
35.25
2
92.61100
6.290
1.48749
70.42
3
-348.39649
0.100
4
72.85426
5.250
1.49700
81.59
5
401.19231
DD[5]
6
61.75210
3.470
1.48749
70.39
7
∞
14.951
8
∞
1.010
1.78590
44.17
9
15.63300
3.160
1.92286
20.89
10
26.73519
2.931
11
-31.18271
1.000
1.91082
35.25
12
-221.14090
DD[12]
13(St)
∞
1.000
*14
20.38050
4.150
1.58313
59.38
*15
211.70314
8.090
16
199.40281
1.000
1.83481
42.73
17
16.50800
5.480
1.49700
81.61
18
-32.80289
DD[18]
19
32.74333
2.580
1.83481
42.73
20
∞
1.567
21
-23.09227
1.430
1.78470
26.27
22
71.40700
3.750
1.73800
32.33
23
-23.27688
DD[23]
24
-92.91465
2.380
1.92119
23.96
25
-26.32000
1.010
1.78800
47.52
26
26.32000
DD[26]
27
-109.91337
3.190
1.58144
40.75
28
-38.02918
26.310
29
∞
2.850
1.54763
54.98
30
∞
1.139
TABLE 2 example 1
WIDE
middle
TELE
Zr
1.0
2.0
4.0
f
72.118
144.236
291.358
FNo.
4.11
4.62
5.76
2ω(°)
21.8
11.0
5.6
DD[5]
0.999
38.238
57.009
DD[12]
13.319
6.720
2.224
DD[18]
3.875
13.038
16.268
DD[23]
12.940
10.585
3.046
DD[26]
2.835
8.681
37.443
[ Table 3]
Example 1
Sn
14
15
KA
1.0000000E+00
1.0000000E+00
A3
0.0000000E+00
0.0000000E+00
A4
-5.7977453E-06
7.0429674E-06
A5
1.9069508E-07
-1.6063152E-07
A6
-1.3138935E-07
-6.4035922E-09
A7
3.3398108E-08
1.7295082E-08
A8
-3.2768000E-09
-2.4892221E-09
A9
7.9633108E-11
9.8110299E-11
A10
5.2428800E-12
3.7353005E-12
Fig. 3 shows respective aberration diagrams in a state where the zoom lens of embodiment 1is focused on an infinite object. In fig. 3, spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification are shown in this order from the left. In fig. 3, the aberration in the WIDE-angle end state is shown in the upper stage labeled "WIDE", the aberration in the intermediate focal length state is shown in the MIDDLE stage labeled "MIDDLE", and the aberration in the telephoto end state is shown in the lower stage labeled "TELE". In the spherical aberration diagram, aberrations in the d-line, C-line, F-line, and g-line are shown by a solid line, a long dashed line, a short dashed line, and a one-dot chain line, respectively. In the astigmatism diagrams, aberrations in d-line in the sagittal direction are shown by solid lines, and aberrations in d-line in the meridional direction are shown by short dashed lines. In the distortion aberration diagram, the aberration under the d-line is shown with a solid line. In the chromatic aberration of magnification diagram, aberrations in the C-line, F-line, and g-line are shown by the long dashed line, short dashed line, and one-dot chain line, respectively. Fno of the spherical aberration diagram indicates the F value, and ω of the other aberration diagrams indicates the half angle of view. In fig. 3, values of fno and ω corresponding to the upper ends of the vertical axes of the respective graphs are shown.
Unless otherwise specified, the symbols, meanings, description methods, and illustration methods of the respective data relating to the above-described example 1 are the same in the following examples, and therefore, the repetitive description thereof will be omitted below.
[ example 2]
Fig. 4 is a sectional view showing a structure at the wide-angle end of the zoom lens of embodiment 2 in a state of focusing on an infinite object. The zoom lens according to embodiment 2 includes, in order from the object side toward the image side along the optical axis Z, a 1 st lens group G1, a 2 nd lens group G2, an aperture stop, a 3 rd lens group G3, a 4 th lens group G4, a 5 th lens group G5, and a 6 th lens group G6. In the zoom lens, upon varying magnification from the wide angle end to the telephoto end, five lens groups of 1 lens group G1 to 5 lens group G5 move along the optical axis Z while changing the interval of adjacent lens groups in the optical axis direction, the 6 th lens group G6 is fixed with respect to the image plane Sim, and the aperture stop St moves integrally with the 3 rd lens group G3. In the zoom lens according to embodiment 2, the intermediate group includes the 3 rd lens group G3 and the 4 th lens group G4, and the subsequent group includes the 5 th lens group G5 and the 6 th lens group G6.
The 1 st lens group G1 includes three lenses L11 to L13 in order from the object side to the image side. The 2 nd lens group G2 includes four lenses L21 to L24 in order from the object side to the image side. The 3 rd lens group G3 includes three lenses L31 to L33 in order from the object side to the image side. The 4 th lens group G4 includes three lenses L41 to L43 in order from the object side to the image side. The 5 th lens group G5 includes three lenses L51 to L53 in order from the object side to the image side. The 6 th lens group G6 includes one lens of lens L61. The vibration isolation group includes three lenses L22 to L24. The focusing group includes a 4 th lens group G4.
With respect to the zoom lens of embodiment 2, basic lens data are shown in table 4, specifications and variable surface intervals are shown in table 5, aspherical coefficients are shown in table 6, and respective aberrations are shown in fig. 5.
[ Table 4]
Example 2
Sn
R
D
Nd
v d
1
250.87223
2.000
1.80610
33.27
2
105.30174
5.927
1.48749
70.42
3
-303.52760
0.100
4
87.46594
4.389
1.49700
81.59
5
399.65657
DD[5]
6
140.62589
2.785
1.48749
70.42
7
-140.62589
8.374
8
∞
1.010
1.83481
42.74
9
18.33540
3.050
1.89286
20.36
10
36.43153
2.712
11
-31.28675
1.000
1.91082
35.25
12
-79.39477
DD[12]
13(St)
∞
0.750
*14
19.98987
4.043
1.58313
59.38
*15
97.37526
6.858
16
35.73001
1.000
1.88300
39.22
17
13.94110
5.223
1.49700
81.59
18
-241.76478
DD[18]
19
132.45690
2.361
1.78800
47.37
20
-50.27079
0.860
21
-23.33672
1.010
1.63980
34.47
22
23.33672
3.750
1.87070
40.73
23
-43.37114
DD[23]
24
76.20188
1.000
1.74100
52.64
25
17.84587
1.707
26
-965.00477
3.782
1.64769
33.79
27
-13.93074
1.000
1.78800
47.37
28
∞
DD[28]
29
-47.33994
2.692
1.91082
35.25
30
-29.43105
26.295
31
∞
2.850
1.54763
54.98
32
∞
1.118
[ Table 5]
Example 2
WIDE
middle
TELE
Zr
1.0
2.0
4.0
f
72.075
144.150
291.184
FNo.
4.12
5.20
5.77
2ω(°)
21.6
11.0
5.6
DD[5]
1.285
43.002
81.265
DD[12]
14.647
6.105
1.786
DD[18]
6.015
8.482
16.446
DD[23]
12.943
12.086
2.270
DD[28]
2.520
13.722
22.611
[ Table 6]
Example 2
Sn
14
15
KA
1.0000000E+00
1.0000000E+00
A3
0.0000000E+00
0.0000000E+00
A4
-1.9928253E-06
8.5881366E-06
A5
-8.7170296E-07
-1.1041250E-06
A6
2.3035450E-07
2.8920056E-07
A7
-3.4175125E-08
-4.3448393E-08
A8
2.1044007E-09
3.2281461E-09
A9
4.0533371E-12
-8.4229097E-11
A10
-5.2428824E-12
-2.4193979E-12
[ example 3]
Fig. 6 is a sectional view showing a structure at the wide-angle end of the zoom lens of embodiment 3 in a state of focusing on an infinite object. The zoom lens according to embodiment 3, in order from the object side toward the image side along the optical axis Z, comprises a 1 st lens group G1, a 2 nd lens group G2, an aperture stop, a 3 rd lens group G3, a 4 th lens group G4, a 5 th lens group G5, and a 6 th lens group G6. In the zoom lens, upon varying magnification from the wide angle end to the telephoto end, five lens groups of 1 lens group G1 to 5 lens group G5 move along the optical axis Z while changing the interval of adjacent lens groups in the optical axis direction, the 6 th lens group G6 is fixed with respect to the image plane Sim, and the aperture stop St moves integrally with the 3 rd lens group G3. In the zoom lens according to embodiment 3, the intermediate group includes the 3 rd lens group G3 and the 4 th lens group G4, and the subsequent group includes the 5 th lens group G5 and the 6 th lens group G6.
The 1 st lens group G1 includes three lenses L11 to L13 in order from the object side to the image side. The 2 nd lens group G2 includes five lenses L21 to L25 in order from the object side to the image side. The 3 rd lens group G3 includes three lenses L31 to L33 in order from the object side to the image side. The 4 th lens group G4 includes two lenses, i.e., lenses L41 to L42, in order from the object side to the image side. The 5 th lens group G5 includes two lenses, lenses L51 to L52, in order from the object side to the image side. The 6 th lens group G6 includes one lens of lens L61. The vibration isolation group includes three lenses L23 to L25. The focusing group includes a 4 th lens group G4.
With respect to the zoom lens of embodiment 3, basic lens data are shown in table 7, specifications and variable surface intervals are shown in table 8, aspherical coefficients are shown in table 9, and respective aberrations are shown in fig. 7.
[ Table 7]
Example 3
Sn
R
D
Nd
v d
1
166.59780
2.000
1.91082
35.25
2
85.11296
6.850
1.53775
74.70
3
-271.98598
0.100
4
67.22483
5.750
1.49700
81.61
5
400.05909
DD[5]
6
46.40002
5.107
1.60300
65.44
7
-86.03107
1.000
1.49700
81.61
8
38.26149
11.857
9
-299.75994
1.010
1.95375
32.32
10
20.93172
2.377
1.98613
16.48
11
44.07436
2.111
12
-32.26585
1.000
1.88300
40.76
13
∞
DD[13]
14(St)
∞
1.500
*15
40.46496
2.953
1.58313
59.38
*16
-70.97676
0.100
17
30.36208
10.625
1.43875
94.66
18
-21.21602
0.100
19
107.96053
1.000
1.90366
31.31
20
20.95730
DD[20]
21
30.43167
4.071
1.84666
23.78
22
-29.10715
2.662
1.98613
16.48
23
-259.11585
DD[23]
24
-87.72723
3.097
1.90366
31.31
25
-18.87620
1.010
1.77250
49.60
26
21.79820
DD[26]
27
2032.60979
4.128
1.48749
70.44
28
-41.52570
29.892
29
∞
2.850
1.54763
54.98
30
∞
1.195
[ Table 8]
Example 3
WIDE
middle
TELE
Zr
1.0
2.0
4.0
f
72.145
144.291
291.467
FNo.
4.13
4.18
5.70
2ω(°)
21.8
10.8
5.6
DD[5]
4.306
33.546
42.787
DD[13]
14.582
8.711
1.296
DD[20]
2.699
17.130
24.557
DD[23]
8.801
6.364
2.748
DD[26]
5.349
3.024
29.594
[ Table 9]
Example 3
Sn
14
15
KA
1.0000000E+00
1.0000000E+00
A3
0.0000000E+00
0.0000000E+00
A4
-7.4717611E-06
2.3402113E-05
A5
-5.7058727E-07
6.4328155E-07
A6
1.2997755E-07
-3.6792554E-08
A7
-1.2190563E-08
-6.4637261E-09
A8
-7.1328468E-10
2.3685359E-09
A9
3.7301651E-10
2.1692872E-11
A10
-2.7539149E11
-1.4225501E-11
[ example 4]
Fig. 8 is a sectional view showing a structure at the wide-angle end of the zoom lens of embodiment 4 in a state of focusing on an infinite object. The zoom lens of embodiment 4, in order from the object side toward the image side along the optical axis Z, comprises a 1 st lens group G1, a 2 nd lens group G2, an aperture stop, a 3 rd lens group G3, a 4 th lens group G4, a 5 th lens group G5, and a 6 th lens group G6. In the zoom lens, upon varying magnification from the wide angle end to the telephoto end, four lens groups of the 1 St lens group G1, the 3 rd lens group G3, the 4 th lens group G4, and the 5 th lens group G5 move along the optical axis Z while changing the interval in the optical axis direction with the adjacent lens groups, the 2 nd lens group G2 and the 6 th lens group G6 are fixed with respect to the image surface Sim, and the aperture stop St moves integrally with the 3 rd lens group G3. In the zoom lens according to embodiment 4, the intermediate group includes the 3 rd lens group G3 and the 4 th lens group G4, and the subsequent group includes the 5 th lens group G5 and the 6 th lens group G6.
The 1 st lens group G1 includes three lenses L11 to L13 in order from the object side to the image side. The 2 nd lens group G2 includes four lenses L21 to L24 in order from the object side to the image side. The 3 rd lens group G3 includes three lenses L31 to L33 in order from the object side to the image side. The 4 th lens group G4 includes three lenses L41 to L43 in order from the object side to the image side. The 5 th lens group G5 includes three lenses L51 to L53 in order from the object side to the image side. The 6 th lens group G6 includes one lens of lens L61. The vibration isolation group includes three lenses L22 to L24. The focusing group includes a 4 th lens group G4.
With respect to the zoom lens of embodiment 4, basic lens data are shown in table 10, specifications and variable surface intervals are shown in table 11, aspherical coefficients are shown in table 12, and respective aberrations are shown in fig. 9.
[ Table 10]
Example 4
Sn
R
D
Nd
v d
1
254.07527
2.000
1.80610
33.27
2
100.16956
6.274
1.48749
70.42
3
-270.04988
0.100
4
83.92452
4.568
1.49700
81.59
5
394.41685
DD[5]
6
183.49891
2.446
1.48749
70.42
7
-183.53469
13.227
8
∞
1.011
1.83481
42.74
9
17.99368
3.250
1.89286
20.36
10
37.83196
2.965
11
-31.07695
1.000
1.95375
32.32
12
-72.72799
DD[12]
13(St)
∞
0.750
*14
20.19515
3.890
1.58313
59.38
*15
80.22129
7.855
16
36.93867
1.000
1.88300
39.22
17
14.36717
5.074
1.49700
81.59
18
-250.69470
DD[18]
19
134.07652
2.386
1.78800
47.37
20
-49.43463
0.857
21
-23.56084
1.135
1.63980
34.47
22
23.56084
3.750
1.87070
40.73
23
-45.52795
DD[23]
24
58.98198
1.000
1.74100
52.64
25
18.33857
1.453
26
144.88405
3.857
1.64769
33.79
27
-14.74163
1.000
1.78800
47.37
28
175.58333
DD[28]
29
-33.66681
2.601
1.80610
33.27
30
-24.66375
26.221
31
∞
2.850
1.54763
54.98
32
∞
1.127
[ Table 11]
Example 4
WIDE
middle
TELE
Zr
1.0
2.0
4.0
f
72.087
144.174
291.231
FNo.
4.12
4.65
5.77
2ω(°)
21.6
11.0
5.6
DD[5]
1.018
41.596
72.481
DD[12]
18.532
9.309
1.726
DD[18]
7.648
10.071
18.476
DD[23]
12.847
11.439
2.292
DD[28]
3.361
11.545
19.862
[ Table 12]
Example 4
Sn
14
15
KA
1.0000000E+00
1.0000000E+00
A3
0.0000000E+00
0.0000000E+00
A4
-1.6693880E-06
7.7614047E-06
A5
-8.3412472E-07
-9.5064558E-07
A6
2.1943876E-07
2.4003477E-07
A7
-3.3899930E-08
-3.7251968E-08
A8
2.4176128E-09
3.2647523E-09
A9
-2.4787767E-11
-1.2773873E-10
A10
-5.2428815E-12
-1.3309567E-12
[ example 5]
Fig. 10 is a sectional view showing a structure at the wide-angle end of the zoom lens of embodiment 5 in a state of focusing on an infinite object. The zoom lens of embodiment 5, in order from the object side toward the image side along the optical axis Z, comprises a 1 st lens group G1, a 2 nd lens group G2, an aperture stop, a 3 rd lens group G3, a 4 th lens group G4, a 5 th lens group G5, and a 6 th lens group G6. In the zoom lens, upon varying magnification from the wide angle end to the telephoto end, five lens groups of 1 lens group G1 to 5 lens group G5 move along the optical axis Z while changing the interval of adjacent lens groups in the optical axis direction, the 6 th lens group G6 is fixed with respect to the image plane Sim, and the aperture stop St moves integrally with the 3 rd lens group G3. In the zoom lens according to embodiment 5, the intermediate group includes the 3 rd lens group G3 and the 4 th lens group G4, and the subsequent group includes the 5 th lens group G5 and the 6 th lens group G6.
The 1 st lens group G1 includes three lenses L11 to L13 in order from the object side to the image side. The 2 nd lens group G2 includes four lenses L21 to L24 in order from the object side to the image side. The 3 rd lens group G3 includes three lenses L31 to L33 in order from the object side to the image side. The 4 th lens group G4 includes three lenses L41 to L43 in order from the object side to the image side. The 5 th lens group G5 includes two lenses, lenses L51 to L52, in order from the object side to the image side. The 6 th lens group G6 includes one lens of lens L61. The vibration isolation group includes three lenses L22 to L24. The focusing group includes a 4 th lens group G4.
With respect to the zoom lens of embodiment 5, the basic lens data are shown in table 13, the specifications and the variable surface intervals are shown in table 14, the aspherical coefficients are shown in table 15, and the respective aberrations are shown in fig. 11.
[ Table 13]
Example 5
Sn
R
D
Nd
v d
1
223.19562
2.000
1.91082
35.25
2
95.18429
6.182
1.48749
70.44
3
-303.16549
0.100
4
73.55061
5.500
1.49700
81.61
5
400.05795
DD[5]
6
66.40803
3.081
1.48749
70.44
7
∞
16.774
8
-173.87769
1.010
1.75500
52.32
9
15.62491
3.250
1.92119
23.96
10
28.62313
2.723
11
-37.40437
1.000
1.91082
35.25
12
∞
DD[12]
13(St)
∞
1.500
*14
24.39651
3.731
1.58313
59.46
*15
640.03276
8.352
16
413.72968
1.000
1.83481
42.74
17
20.55215
5.098
1.49700
81.61
18
-28.05035
DD[18]
19
33.84068
2.449
1.78800
47.37
20
∞
1.025
21
-35.21923
2.750
1.75575
24.71
22
125.00563
4.510
1.72047
34.71
23
-34.31286
DD[23]
24
-139.08043
1.842
1.92119
23.96
25
-29.72012
1.010
1.78800
47.37
26
24.18590
DD[26]
27
-55.68093
2.419
1.66382
27.35
28
-34.02470
29.353
29
∞
2.850
1.54763
54.98
30
∞
1.146
[ Table 14]
Example 5
WIDE
middle
TELE
Zr
1.0
2.0
4.0
f
72.102
144.205
291.294
FNo.
4.12
4.66
5.77
2ω(°)
22.0
11.0
5.6
DD[5]
1.000
37.755
56.634
DD[12]
13.628
7.078
2.453
DD[18]
3.198
15.274
18.788
DD[23]
11.464
9.194
1.993
DD[26]
3.467
7.657
34.630
[ Table 15]
Example 5
Sn
14
15
KA
1.0000000E+00
1.0000000E+00
A3
0.0000000E+00
0.0000000E+00
A4
-1.8476524E-06
1.0156779E-05
A5
5.0693734E-07
4.6058114E-07
A6
-1.2840468E-07
-1.0184763E-07
A7
1.3047210E-08
6.1814506E-09
A8
-4.1064596E-10
6.1484724E-10
A9
-2.5544624E-11
-1.0649134E-10
A10
1.3165304E-12
3.7829322E-12
Table 16 shows the correspondence values of conditional expressions (1) to (30) of the zoom lenses of embodiments 1 to 5.
[ Table 16]
Formula number
Formula (II)
Example 1
Example 2
Example 3
Example 4
Example 5
(1)
DL1/Lw
0.75
0.83
0.61
0.61
0.74
(2)
|(1-βist)×βisrt|
5.05
3.92
5.19
3.77
4.99
(3)
fmA/fmB
0.95
1.02
0.96
1.07
0.90
(4)
DmAB/fmB
0.38
0.39
0.66
0.43
0.42
(5)
|(1-βmBt2)×βmBrt2|
6.56
5.70
6.71
5.10
6.63
(6)
Llist/f1
0.610
0.655
0.585
0.655
0.613
(7)
fw/|fis|
3.73
2.84
3.82
2.77
3.71
(8)
fw/fmw
2.53
2.44
3.16
2.27
2.62
(9)
ft/fmt
8.14
8.16
7.98
7.59
8.06
(10)
fmt/fmw
1.25
1.21
1.60
1.21
1.30
(11)
fw/|fsmax|
2.54
3.14
2.84
2.76
2.46
(12)
ft/fw
4.04
4.04
4.04
4.04
4.04
(13)
Lw/fw
1.52
1.38
1.47
1.54
1.53
(14)
Bfw/fw
0.41
0.41
0.46
0.40
0.45
(15)
(R1r+R2f)/(R1r-R2f)
1.36
2.09
1.26
2.74
1.40
(16)
|(1-βisw)×βisrw
2.44
2.27
2.53
2.10
2.40
(17)
|(1-βmBw2)×βmBrw2|
3.34
4.19
4.35
3.93
3.68
(18)
fw/f1
0.49
0.45
0.66
0.47
0.49
(19)
ft/f1
2.00
1.82
2.68
1.89
1.98
(20)
ft/|f2|
10.25
8.47
13.69
8.60
10.36
(21)
fmw/|f2|
1.00
0.86
1.07
0.94
0.98
(22)
fmt/|f2|
1.26
1.04
1.72
1.13
1.29
(23)
v mp
81.61
81.59
94.66
81.59
81.61
(24)
v 2p
70.39
70.42
65.44
70.42
70.44
(25)
(R1f+R1r)/(R1f-R1r)
-3.12
-4.37
-2.43
-4.62
-3.52
(26)
v ave1p
76.01
76.01
78.16
76.01
76.03
(27)
v ave2n
39.71
39.00
51.56
37.53
43.79
(28)
v avemp
70.50
70.49
77.02
70.49
70.54
(29)
visp
20.89
20.36
32.32
20.36
23.96
(30)
fw/|f2|
2.54
2.10
3.39
2.13
2.57
As is clear from the above data, the zoom lenses of embodiments 1 to 5 are configured to have vibration-proof performance, have a zoom magnification of 4 times or more, achieve downsizing and weight reduction, and achieve high optical performance by excellently correcting each aberration. The zoom lenses according to embodiments 1 to 5 are suitable as telephoto zoom lenses, for example.
Next, an imaging device according to an embodiment of the present invention will be described. Fig. 12 and 13 show external views of a camera 30 as an imaging device according to an embodiment of the present invention. Fig. 12 is a perspective view of the camera 30 viewed from the front side, and fig. 13 is a perspective view of the camera 30 viewed from the back side. The camera 30 is a so-called non-reflective digital camera, and the interchangeable lens 20 is detachably attached thereto. The interchangeable lens 20 includes the zoom lens 1 according to one embodiment of the present invention accommodated in the lens barrel.
The camera 30 includes a camera body 31, and a shutter button 32 and a power button 33 are provided on an upper surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 are provided on the back surface of the camera body 31. The display unit 36 can display the captured image and the image existing in the angle of view before the capturing.
A photographing opening into which light from a subject is incident is provided in the center of the front of the camera body 31, a mount 37 is provided at a position corresponding to the photographing opening, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.
The camera body 31 is provided with an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to a subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, a recording medium that records the generated image, and the like. In the camera 30, a still image or a moving image can be photographed by pressing the shutter button 32, and image data obtained by the photographing is recorded in the above-described recording medium.
The technique of the present invention has been described above by referring to the embodiments and examples, but the technique of the present invention is not limited to the embodiments and examples described above, and various modifications are possible. For example, the curvature radius, surface interval, refractive index, dispersion coefficient, aspherical surface coefficient, and the like of each lens are not limited to those shown in the above embodiments, and other values may be used.
The imaging device according to the embodiment of the present invention is not limited to the above example, and various embodiments such as a non-transreflective camera, a film camera, and a video camera may be used.
Description of the symbols
1-zoom lens, 20-interchangeable lens, 30-camera, 31-camera body, 32-shutter button, 33-power button, 34, 35-operation section, 36-display section, 37-bayonet, DL 1-difference in optical axis direction of position of 1 lens group under telephoto end and position of 1 lens group under wide angle end, G1-1 lens group, G2-2 lens group, G3-3 lens group, G4-4 lens group, G5-5 lens group, G6-6 lens group, L11-L61-lens, lllist-distance in optical axis from lens surface of whole system at most object side to lens surface of vibration-proof group under telephoto end, Lw-distance in optical axis from lens surface of whole system at most object side to lens surface of whole system at most image side under wide angle end to lens surface of whole system at most object side at wide angle end The beams on the ma, ta, wa-axes, the beams at mb, tb, wb-maximum viewing angle, the PP-optics, the Sim-image plane, the St-aperture stop, the Z-axis.
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