JP5669971B2 - Anti-vibration zoom lens optical system - Google Patents

Description

  The present invention relates to an anti-vibration zoom lens optical system for a single-lens reflex camera using a film or a solid-state imaging device.

Conventionally, zoom lenses having an anti-vibration function and a zoom ratio of about 4 times have been proposed as follows.
Located in positive, negative, positive, positive, negative 5-group zoom lens, or positive, negative, positive, negative, positive, negative 6-group zoom lens, moving the negative second lens group for image stabilization It is the structure to make (for example, refer patent document 1).

  The zoom lens is a positive, negative, negative, positive, negative five-group zoom lens with a zoom ratio of 4.1, and is configured to move a part of the positive fourth lens group for image stabilization (see FIG. For example, see Patent Document 2).

  The zoom ratio is 3.5, which is a positive, negative, and positive three-group zoom, in which a part of the positive third lens group is moved for image stabilization (for example, Patent Document 3). reference)

JP-A-8-62451 JP-A-10-133114 JP 2007-206542 A

  The embodiments of Patent Documents 1 and 2 have a problem that the effective diameter of the lens group to be moved for image stabilization is as large as 25 mm or more, which increases the size of the image stabilization mechanism and makes it difficult to reduce the size of the zoom lens. is there. In addition, since there are five or more zoom lens groups, there is a problem that the zoom mechanism becomes complicated.

  In the embodiment in Patent Document 3, the positive third lens group is divided into a positive 31st lens group, a negative 32nd lens group, and a 33rd lens group from the object side, and only the 32nd lens group is orthogonal to the optical axis. The anti-shake correction is performed by moving in the direction, but the position of the iris unit and the anti-shake unit attached to the third lens group are close, so the parts that drive the iris interfere with the parts of the anti-shake mechanism, There is a problem that the lens barrel structure is complicated.

(Object of invention)
The present invention has been made in view of the above-described problems of a zoom lens having a conventional anti-shake function and a zoom ratio of about 4 times, and the effective diameter of a lens group that is moved for anti-shake correction is large. An object of the present invention is to provide an anti-vibration zoom lens optical system that is small and capable of reducing the size of the anti-vibration mechanism, and further includes four zoom lens groups, and does not require complicated lens barrel mechanisms.

  The present invention also provides an anti-vibration zoom lens optical system in which an aperture unit and an anti-vibration unit are arranged at an appropriate distance so that the drive system of the aperture unit and the drive system of the anti-vibration mechanism can be arranged without interference. The purpose is to do.

The vibration-proof zoom lens optical system of the present invention is
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power And
The fourth lens group includes, in order from the object side, a forty-first lens group, a forty-second lens group having negative refractive power, and a forty-third lens group, and the forty-second lens group extends in a direction orthogonal to the optical axis. By moving it, image blur correction on the image plane is performed,
In the first lens group, the Abbe number of at least one positive lens is 80 or more,
The distance between the first lens group and the second lens group is widened by zooming from the wide-angle end to the telephoto end, the distance between the second lens group and the third lens group is narrowed, and the third lens group And the fourth lens group moves to the object side with different movement amounts,
An anti-vibration zoom lens optical system that satisfies the following conditions: (1) -0.5 <f42 / f43 <0.2
Where f42 is the focal length of the forty-second lens group, and f43 is the focal length of the forty-third lens group.

  In addition to being able to perform excellent aberration correction, the anti-vibration zoom lens optical system of the present invention has a small effective diameter of the lens group that is moved for anti-vibration correction, and the anti-vibration mechanism can be downsized. Furthermore, there are four zoom lens groups, and there is an effect that it is not necessary to complicate the lens barrel mechanism.

  In the image stabilization zoom lens optical system of the present invention, the aperture unit and the image stabilization unit are arranged at an appropriate distance, and the drive system of the aperture unit and the drive system of the image stabilization mechanism can be disposed without interference. Has the effect of being.

  In the image stabilizing zoom lens optical system according to the present invention, in the first lens group, the Abbe number of at least one positive lens is 80 or more.

With this configuration, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and 4 zoom lens groups. It is not necessary to complicate the mechanism, the aperture unit and the vibration isolation unit are arranged at an appropriate distance, and the drive system of the aperture unit and the drive system of the vibration isolation mechanism can be arranged without interference The effectiveness of such effects can be enhanced.
According to this configuration, it is further possible to obtain the effect of reducing the chromatic aberration on the telephoto side. That is, when the Abbe number of at least one positive lens is less than 80, the telephoto side axial chromatic aberration and the chromatic aberration of magnification increase, resulting in a problem of color shift.

    In the image stabilizing zoom lens optical system according to the present invention, an interval between the first lens group and the second lens group is widened by zooming from a wide angle end to a telephoto end, and the second lens group and the third lens group are arranged. The distance from the lens group is narrowed, and the third lens group and the fourth lens group move toward the object side with different movement amounts.

  According to this configuration, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group There are four groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are appropriately spaced from each other, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism do not interfere with each other Effectiveness of effects such as being capable of being arranged can be enhanced.

  Conditional expression (1) of the present invention defines an appropriate range of the focal length of the forty-second lens group. When the upper limit of conditional expression (1) is exceeded, the negative refractive power of the forty-second lens group increases, and the ratio of the amount of image movement on the image plane to the amount of movement of the forty-second lens group during blur correction increases. Therefore, an allowable amount of movement error of the forty-second lens group at the time of blur correction becomes small, and movement control of the forty-second lens becomes difficult. In addition, it is difficult to correct coma at the time of blur correction. If the lower limit of conditional expression (1) is exceeded, the negative refractive power of the forty-second lens group becomes small, and the ratio of the amount of image movement on the image plane to the amount of movement of the forty-second lens during blur correction becomes small. Since the amount of movement of the forty-second lens required for shake correction increases, the shake correction mechanism increases in size. In addition, it is difficult to correct coma at the time of blur correction.

[Embodiment of the Invention]
An embodiment of the present invention is characterized in that the following conditional expression is satisfied.
(2) 1.1 <d41 / d42 <4.5
(3) 0 <f4
However, d41 is the air space between the 41st lens group and the 42nd lens group. D42 is the air space between the 42nd lens group and the 43rd lens group. F4 is the focal length of the 4th lens group.

  According to this embodiment, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for the image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group. 4 groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are disposed at an appropriate distance, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism interfere with each other. It is possible to increase the effectiveness of such effects as being able to be arranged without any problems.

  Conditional expression (2) defines an appropriate arrangement of the forty-second lens group within the fourth lens group. When the upper limit value of conditional expression (2) is exceeded, the overall length of the zoom lens becomes large, and the aperture and the forty-second lens group are greatly separated, making it difficult to correct spherical aberration and coma. If the lower limit of conditional expression (2) is exceeded, the effective diameter of the forty-second lens group will increase, leading to an increase in the size of the vibration isolation mechanism and difficulty in correcting spherical aberration and axial chromatic aberration.

Conditional expression (3) defines that the focal length of the fourth lens group including the lens group that performs the image stabilization correction is positive. The fourth lens group has a positive refractive power, the 41st lens group has a positive refractive power, and the 42nd lens group has a negative refractive power, so that the effective diameter of the 42nd lens group is changed from the first lens group to the 41st lens. Since the lens group can be made smaller than the effective diameter of the lens group, it is possible to reduce the size of the vibration isolation mechanism, which is advantageous for reducing the size of the entire zoom lens.
Further, since the forty-second lens group for image stabilization is configured in the fourth lens group, the distance from the diaphragm in front of the third lens group becomes long, so the unit constituting the diaphragm, for example, the diaphragm drive motor A degree of freedom is created in the arrangement and the arrangement of the vibration isolation unit. Further, with such a configuration, it is possible to reduce degradation of imaging performance such as coma aberration when the forty-second lens group is moved in the direction orthogonal to the optical axis.

  Another embodiment of the present invention is characterized in that the forty-first lens group has a positive refractive power.

According to this embodiment, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for the image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group. 4 groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are disposed at an appropriate distance, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism interfere with each other. It is possible to increase the effectiveness of such effects as being able to be arranged without any problems.
According to this embodiment, it is further possible to obtain an effect that coma aberration, particularly coma aberration fluctuation at the time of image stabilization can be suppressed.

  Another embodiment of the present invention is characterized in that the 41st lens group of the fourth lens group includes two or more positive lenses including a positive lens cemented with a negative lens.

According to this embodiment, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for the image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group. 4 groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are disposed at an appropriate distance, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism interfere with each other. It is possible to increase the effectiveness of such effects as being able to be arranged without any problems.
According to this embodiment, the effect that the lateral chromatic aberration can be further reduced can be obtained.

Another embodiment of the present invention is characterized by satisfying the following conditions.
(4) -1.0 <f4 / f43 <4.0
Where f4 is the focal length of the fourth lens group, f42 is the focal length of the 42nd lens group, and f43 is the focal length of the 43rd lens group.

  According to this embodiment, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for the image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group. 4 groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are disposed at an appropriate distance, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism interfere with each other. It is possible to increase the effectiveness of such effects as being able to be arranged without any problems.

  According to this embodiment, it is possible to perform excellent aberration correction as described above, the effective diameter of the lens group to be moved for the image stabilization correction is small, the size of the image stabilization mechanism can be reduced, and the zoom lens group. 4 groups, and it is not necessary to complicate the mechanism, the diaphragm unit and the vibration isolation unit are disposed at an appropriate distance, and the drive system of the diaphragm unit and the drive system of the vibration isolation mechanism interfere with each other. It is possible to increase the effectiveness of such effects as being able to be arranged without any problems.

  Conditional expression (4) defines an appropriate range of the focal length of the 43rd lens group. If the upper limit value of conditional expression (4) is exceeded, the positive refractive power of the 43rd lens group will increase, the zoom lens will become larger, and it will be difficult to correct distortion. When the lower limit of conditional expression (4) is exceeded, the refractive power of the 43rd lens group becomes small, the spherical aberration becomes excessively negative, and it becomes difficult to correct the aberration.

It is sectional drawing of the vibration proof zoom lens optical system of Embodiment 1 of this invention. It is explanatory drawing which shows the zoom movement of each lens group in Embodiment 1 of this invention. FIG. 3 is an aberration diagram of spherical aberration, astigmatism, and distortion at the wide angle end according to Embodiment 1 of the present invention. It is an aberration diagram of coma aberration at the wide angle end in Embodiment 1 of the present invention. FIG. 4 is an aberration diagram of spherical aberration, astigmatism, and distortion in the intermediate region in Embodiment 1 of the present invention. FIG. 2 is a coma aberration diagram in an intermediate region in Embodiment 1 of the present invention. FIG. 3 is an aberration diagram of spherical aberration, astigmatism, and distortion at the telephoto end according to the first embodiment of the present invention. It is a coma aberration diagram at the telephoto end in Embodiment 1 of the present invention. It is a coma aberration figure (plus side shift) of the wide angle end in Embodiment 1 of this invention. It is a coma aberration figure (plus side shift) of the telephoto end in Embodiment 1 of the present invention. It is a coma aberration figure (minus side shift) of the telephoto end in Embodiment 1 of the present invention. FIG. 6 is a lens cross-sectional view at a wide angle end in an image stabilizing zoom lens optical system according to Embodiment 2 of the present invention. It is explanatory drawing which shows the zoom movement of each lens group in Embodiment 2 of this invention. FIG. 6 is an aberration diagram of spherical aberration, astigmatism, and distortion at the wide angle end according to Embodiment 2 of the present invention. It is a coma aberration figure of the wide angle end in Embodiment 2 of this invention. FIG. 10 is an aberration diagram of spherical aberration, astigmatism, and distortion in the intermediate region in Embodiment 2 of the present invention. It is a coma aberration figure of the intermediate region in Embodiment 2 of the present invention. FIG. 6 is an aberration diagram of spherical aberration, astigmatism, and distortion at the telephoto end according to Embodiment 2 of the present invention. It is a coma aberration figure of the telephoto end in Embodiment 2 of this invention. It is a coma aberration figure (plus side shift) of the wide angle end in Embodiment 2 of the present invention. It is a coma aberration figure (plus side shift) of the telephoto end in Embodiment 2 of this invention. It is a coma aberration figure (minus side shift) of a telephoto end in Embodiment 2 of the present invention.

Regarding the attached aberration diagrams, in the spherical aberration graph, the vertical axis represents the ratio of the entrance pupil height.
Reference numeral 1 denotes an aberration at the d-line (587.56 nm).
2 is the aberration at the g-line (435.83 nm).
In the astigmatism diagram,
The vertical axis (IMG HT) represents the image height.
Solid line Sphere missing direction Dotted line Indicates meridian direction.
In the distortion diagram,
The vertical axis (IMG HT) represents the image height.
In the coma aberration diagram,
Horizontal axis Entrance pupil height Solid line Aberration at d-line (587.56nm) Dotted line Shows aberration at g-line (435.83nm).

Embodiments of the present invention will be described below with reference to the accompanying drawings.
(First embodiment)
The anti-vibration zoom lens optical system according to the first embodiment includes a first lens group I including a first lens 1, a second lens 2, and a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6. The second lens group II, the diaphragm 7, the eighth lens 8, the ninth lens 9, and the tenth lens 10, the third lens group III, the eleventh lens 11, the twelfth lens 12, the thirteenth lens 13, and the fourteenth lens. 14 includes a fourth lens group IV including a fifteenth lens 15, a sixteenth lens 16, a seventeenth lens 17, and an eighteenth lens 18.

The optical data of the image stabilizing zoom lens optical system according to the first embodiment is as follows.

(Second Embodiment)
The anti-vibration zoom lens optical system according to the second embodiment includes a first lens group I including a first lens 1, a second lens 2, and a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6. The second lens group II, the diaphragm 7, the eighth lens 8, the ninth lens 9, and the tenth lens 10, the third lens group III, the eleventh lens 11, the twelfth lens 12, the thirteenth lens 13, and the fourteenth lens. 14 includes a fourth lens group IV including a fifteenth lens 15, a sixteenth lens 16, a seventeenth lens 17, and an eighteenth lens 18.

The optical data of the image stabilizing zoom lens optical system according to the second embodiment is as follows.

I to IV 1st lens group to 4th lens group 1 to 18 1st lens to 18th lens 7 Diaphragm 101 to 118 1st lens to 18th lens 108 Diaphragm

Claims (5)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power And
The fourth lens group includes, in order from the object side, a forty-first lens group, a forty-second lens group having negative refractive power, and a forty-third lens group, and the forty-second lens group extends in a direction orthogonal to the optical axis. By moving it, image blur correction on the image plane is performed,
In the first lens group, the Abbe number of at least one positive lens is 80 or more,
The distance between the first lens group and the second lens group is widened by zooming from the wide-angle end to the telephoto end, the distance between the second lens group and the third lens group is narrowed, and the third lens group And the fourth lens group moves to the object side with different movement amounts,
An anti-vibration zoom lens optical system that satisfies the following conditions:
(1) -0.5 <f42 / f43 <0.2
Where f42 is the focal length of the forty-second lens group f43 is the focal length of the forty-third lens group 2. The image stabilizing zoom lens optical system according to claim 1, wherein the following conditional expression is satisfied.
(2) 1.1 <d41 / d42 <4.5
(3) 0 <f4
However, d41 is the air space between the 41st lens group and the 42nd lens group. D42 is the air space between the 42nd lens group and the 43rd lens group. F4 is the focal length of the 4th lens group.   The anti-vibration zoom lens optical system according to claim 1, wherein the forty-first lens group has a positive refractive power.   4. The structure according to claim 1, wherein, in the fourth lens group, the 41st lens group includes two or more positive lenses including a positive lens cemented with a negative lens. 5. The vibration-proof zoom lens optical system described. 5. The image stabilizing zoom lens optical system according to claim 1, wherein the following condition is satisfied.
(4) -1.0 <f4 / f43 <4.0
Where f4 is the focal length of the fourth lens group, and f43 is the focal length of the 43rd lens group.

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