JP2012027309A - Zoom lens, optical device and method for manufacturing zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact zoom lens having excellent optical performance, an optical device and a method for manufacturing the zoom lens.SOLUTION: A zoom lens comprises, from a side closest to an object, a first lens group G1 and a second lens group G2. When magnification is varied from a wide angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2 is changed. The second lens group G2 is composed of, in order from the object side, a 2a part of lens group G2a and a 2b part of lens group G2b. The 2a part of lens group G2a is composed of a plurality of lens components having refractive power of the same sign, and the 2b part of lens group G2b comprises a lens component having refractive power of different sign from that of the plurality of lens components in the 2a part of lens group G2a on the side closest to the object. The zoom lens satisfies a predetermined conditional expression.

Description

  The present invention relates to a zoom lens, an optical device, and a method for manufacturing a zoom lens.

  Conventionally, zoom lenses suitable for photographic cameras, electronic still cameras, video cameras, and the like have been proposed (see, for example, Patent Document 1).

JP 2004-21223 A

However, the conventional zoom lens has a problem that it is large and does not have sufficient optical performance.
Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a zoom lens, an optical device, and a zoom lens manufacturing method that are small and have excellent optical performance.

In order to solve the above problems, the present invention
In order from the most object side, it has a first lens group and a second lens group,
When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is changed,
The second lens group includes, in order from the object side, a 2a partial lens group and a 2b partial lens group,
The second-a partial lens group includes a plurality of lens components having the same refractive power sign,
The 2b partial lens group has a lens component having a refractive power with a sign different from the sign of the refractive power of the plurality of lens components in the 2a partial lens group on the most object side,
Provided is a zoom lens that satisfies the following conditional expression.
0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the group

The present invention also provides
An optical apparatus comprising the zoom lens is provided.
The present invention also provides
A method of manufacturing a zoom lens having a first lens group and a second lens group in order from the most object side,
The second lens group includes, in order from the object side, a second a partial lens group and a second b partial lens group, and the second a partial lens group includes a plurality of lens components having the same refractive power sign, The second-b partial lens group has a lens component having a refractive power of a sign different from a refractive power sign of the plurality of lens components in the second-a partial lens group on the most object side;
The 2a partial lens group and the 2b partial lens group satisfy the following conditional expression:
A zoom lens manufacturing method is provided in which the distance between the first lens group and the second lens group is changed when zooming from the wide-angle end state to the telephoto end state.
0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the group

  According to the present invention, it is possible to provide a zoom lens, an optical apparatus, and a zoom lens manufacturing method that are small and have excellent optical performance.

It is sectional drawing which shows the structure of the zoom lens which concerns on 1st Example of this application. (A), (b), and (c) are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 1 of the present application, respectively. It is. (A), (b), and (c) are respectively when the zoom lens according to the first embodiment of the present application is in focus at a short-distance object in the wide-angle end state, the intermediate focal length state, and the telephoto end state (shooting magnification − It is an aberration diagram at 0.01 times). (A) and (b) are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 1 of the present application, respectively. It is sectional drawing which shows the structure of the zoom lens which concerns on 2nd Example of this application. (A), (b), and (c) are various aberration diagrams when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 2 of the present application, respectively. It is. (A), (b), and (c) are respectively when focusing on a short-distance object in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 2 of the present application (shooting magnification − It is an aberration diagram at 0.01 times). (A) and (b) are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively. It is sectional drawing which shows the structure of the zoom lens which concerns on 3rd Example of this application. (A), (b), and (c) are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 3 of the present application, respectively. It is. (A), (b), and (c) are respectively when focusing on a short-distance object in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 3 of the present application (shooting magnification − It is an aberration diagram at 0.01 times). (A) and (b) are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 3 of the present application, respectively. It is sectional drawing which shows the structure of the zoom lens which concerns on 4th Example of this application. (A), (b), and (c) are various aberration diagrams during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 4 of the present application, respectively. It is. (A), (b), and (c) are for focusing on a short-distance object in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 4 of the present application (shooting magnification − It is an aberration diagram at 0.01 times). (A) and (b) are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 4 of the present application, respectively. It is sectional drawing which shows the structure of the zoom lens which concerns on 5th Example of this application. (A), (b), and (c) are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 5 of the present application. It is. (A), (b), and (c) are respectively when focusing on a short-distance object in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 5 of the present application (shooting magnification − It is an aberration diagram at 0.01 times). (A) and (b) are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 5 of the present application, respectively. It is a figure which shows the structure of the camera provided with the zoom lens of this application. It is a figure which shows the outline of the manufacturing method of the zoom lens of this application.

Hereinafter, the zoom lens, the optical device, and the manufacturing method of the zoom lens of the present application will be described.
The zoom lens of the present application includes a first lens group and a second lens group in order from the most object side, and when zooming from the wide-angle end state to the telephoto end state, the first lens group and the second lens group The distance from the lens group is changed, and the second lens group is composed of a 2a partial lens group and a 2b partial lens group in order from the object side, and the second a partial lens group has a sign of refractive power. The 2b partial lens group is composed of the same plurality of lens components, and the lens component having a refractive power with a sign different from the sign of the refractive power of the plurality of lens components in the 2a partial lens group is located closest to the object side. The following conditional expression (1) is satisfied.
(1) 0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the group

  The zoom lens of the present application can reduce the occurrence of spherical aberration by arranging the 2a partial lens group having the above-described configuration in the second lens group. In the zoom lens of the present application, the occurrence of curvature of field can be mitigated by arranging the second-b partial lens group having the above-described configuration in the second lens group. The lens component refers to a single lens or a cemented lens formed by cementing two or more lenses.

Conditional expression (1) defines an appropriate range of the overall length ratio of the 2a partial lens group and the 2b partial lens group. The zoom lens according to the present application can satisfactorily correct curvature of field, coma, and spherical aberration by satisfying conditional expression (1), and can prevent the enlargement of the entire zoom lens.
When the corresponding value of the conditional expression (1) of the zoom lens of the present application exceeds the upper limit value, the value of Σ2a increases, and although the spherical aberration generated in the 2a partial lens group decreases, the total length of the 2a partial lens group becomes smaller. This is not preferable because the zoom lens becomes large and the entire zoom lens becomes large. In addition, the field curvature and coma generated in the second b partial lens group cannot be sufficiently relaxed. Further, although the value of Σ2b is reduced and the 2b partial lens group is reduced in size, field curvature and coma generated in the 2b partial lens group are increased. Further, it is not preferable because the spherical aberration generated in the second-a partial lens group is excessively corrected.
In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 12.00 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 7.00 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 6.53 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 6.05 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 5.58 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 5.10 or less.

On the other hand, when the corresponding value of the conditional expression (1) of the zoom lens of the present application is less than the lower limit value, the value of Σ2a becomes small, and the 2a partial lens group is downsized, but the spherical aberration generated in the 2a partial lens component Is unfavorable because it becomes large. In addition, the 2b partial lens group is enlarged, and it is not preferable because the spherical aberration generated in the 2a partial lens group cannot be sufficiently corrected. Further, the value of Σ2b is increased, the second b partial lens group is enlarged, and the entire zoom lens is enlarged, which is not preferable. In addition, it is not preferable because the spherical aberration generated in the second-a partial lens group cannot be sufficiently corrected.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (1) to 0.66 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 1.02 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 1.42 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 1.82 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 2.22 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 2.52 or more.
With the above configuration, a zoom lens having a small size and excellent optical performance can be realized.

In addition, it is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 0.10 <| fa / fb | <2.00
However,
fa: focal length of the 2a partial lens group fb: focal length of the 2b partial lens group

Conditional expression (2) defines an appropriate range of the focal length ratio of the 2a partial lens group and the 2b partial lens group. The zoom lens of the present application satisfies the conditional expression (2), so that coma aberration, field curvature, and spherical aberration generated in the second lens group can be reduced in the second lens group.
When the corresponding value of the conditional expression (2) of the zoom lens of the present application exceeds the upper limit value, fa becomes larger than fb, and it is possible to sufficiently correct field curvature and coma generated in the 2b partial lens group. Since it becomes impossible, it is not preferable. Further, fb becomes smaller than fa, and field curvature and coma generated in the 2b partial lens group are increased, which is not preferable.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.83 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.65 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.48 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (2) to 1.30 or less.

On the other hand, if the corresponding value of the conditional expression (2) of the zoom lens of the present application is less than the lower limit value, fb becomes larger than fa, and the spherical aberration generated in the 2a partial lens group cannot be sufficiently corrected. This is not preferable. Further, since fa becomes smaller than fb, and spherical aberration generated in the second-a partial lens group becomes large, it is not preferable.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.12 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.13 or more. In order to secure the effect of the present application, it is more preferable that the lower limit value of conditional expression (2) is 0.15 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (2) to 0.16 or more.

  In the zoom lens of the present application, at least a part of the plurality of lens components in the second-a partial lens group is moved in the optical axis direction as a focusing lens group to focus from an object at infinity to a near object. It is desirable to do. With this configuration, it is possible to suppress spherical aberration and variation in field curvature when focusing from an infinitely distant object to a close object.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 0.15 <| fw / ff | <0.45
However,
fw: focal length of the zoom lens in the wide-angle end state ff: focal length of the focusing lens group

Conditional expression (3) defines an appropriate range of the focal length ratio between the zoom lens and the focusing lens group in the wide-angle end state. The zoom lens of the present application can satisfactorily correct spherical aberration and coma aberration by satisfying conditional expression (3). Further, the position control of the focusing lens group becomes easy, and the enlargement of the entire zoom lens can be prevented.
When the corresponding value of conditional expression (3) of the zoom lens of the present application exceeds the upper limit value, the focal length of the focusing lens group becomes small, and position control of the focusing lens group becomes difficult. For this reason, since it becomes impossible to ensure the precision of focusing sufficiently, it is not preferable. Further, since the focusing lens group alone causes spherical aberration and coma aberration, it is not preferable.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 0.43 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (3) to 0.41 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 0.38 or less.

On the other hand, when the corresponding value of conditional expression (3) of the zoom lens of the present application is less than the lower limit value, the focal length of the focusing lens group increases, and the amount of movement of the focusing lens group during focusing increases. For this reason, the entire length of the zoom lens is increased, and the lens diameter is also increased, so that the entire zoom lens is undesirably enlarged. Further, it is not preferable because spherical aberration and coma generated by the focusing lens unit alone cannot be sufficiently corrected.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 0.17 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 0.19 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 0.21 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (3) to 0.23 or more.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (4).
(4) 0.15 <| fγw | <0.60
However,
fγw: an image plane movement coefficient of the focusing lens group in the wide-angle end state

Conditional expression (4) defines an appropriate range of the image plane movement coefficient (the ratio of the moving amount of the image plane to the moving amount of the focusing lens group) of the focusing lens group in the wide-angle end state. By satisfying conditional expression (4), the zoom lens of the present application can minimize the change in imaging performance from the time of focusing on an object at infinity to the time of focusing on an object at a short distance. Further, the position control of the focusing lens group becomes easy, and the enlargement of the entire zoom lens can be prevented.
When the corresponding value of conditional expression (4) of the zoom lens of the present application exceeds the upper limit value, the focal length of the focusing lens group increases, and the amount of movement of the focusing lens group during focusing increases. For this reason, the entire length of the zoom lens is increased, and the lens diameter is also increased, so that the entire zoom lens is undesirably enlarged. Further, it is not preferable because spherical aberration and coma generated by the focusing lens unit alone cannot be sufficiently corrected.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (4) to 0.58 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (4) to 0.55 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (4) to 0.53 or less.

On the other hand, when the corresponding value of conditional expression (4) of the zoom lens of the present application is below the lower limit value, the focal length of the focusing lens group becomes small, and the position control of the focusing lens group becomes difficult. For this reason, since it becomes impossible to ensure the precision of focusing sufficiently, it is not preferable. Further, since the focusing lens group alone causes spherical aberration and coma aberration, it is not preferable.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 0.18 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (4) to 0.22 or more. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (4) to 0.25 or more.

  In the zoom lens of the present application, it is desirable that at least a part of the second lens group is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thereby, it is possible to correct (shake-proof) image blur caused by camera shake or the like. In addition, as described above, when at least a part of the second lens group is a shift lens group, coma generated in the shift lens group can be corrected by other lens components in the second lens group, and the shift is performed. It is possible to suppress fluctuations in coma aberration when the lens group is moved so as to include a component in a direction orthogonal to the optical axis (at the time of lens shift).

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (5).
(5) -3.70 <ff / fs <3.10
However,
ff: focal length of the focusing lens group fs: focal length of the shift lens group

Conditional expression (5) defines an appropriate range of the focal length ratio between the focusing lens group and the shift lens group. The zoom lens of the present application can satisfactorily correct spherical aberration, coma, decentering coma, and field curvature by satisfying conditional expression (5). Further, the position control of the focusing lens group and the shift lens group becomes easy, and the enlargement of the entire zoom lens can be prevented.
When the corresponding value of conditional expression (5) of the zoom lens of the present application exceeds the upper limit value, the focal length of the focusing lens group increases, and the amount of movement of the focusing lens group during focusing increases. For this reason, the entire length of the zoom lens is increased, and the lens diameter is also increased, so that the entire zoom lens is undesirably enlarged. Further, it is not preferable because spherical aberration and coma generated by the focusing lens unit alone cannot be sufficiently corrected. Further, the focal length of the shift lens group becomes small, and the position control of the shift lens group becomes difficult. For this reason, it is not preferable because sufficient accuracy of image blur correction cannot be ensured. In addition, it becomes difficult to correct coma and decentered coma.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (5) to 2.68 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (5) to 2.25 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (5) to 1.83 or less.

On the other hand, if the corresponding value of conditional expression (5) of the zoom lens of the present application is less than the lower limit value, the focal length of the focusing lens group becomes small, and position control of the focusing lens group becomes difficult. For this reason, since it becomes impossible to ensure the precision of focusing sufficiently, it is not preferable. Further, since the focusing lens group alone causes spherical aberration and coma aberration, it is not preferable. In addition, the focal length of the shift lens group becomes large, and the shift lens group must be shifted more in order to correct image blur, which is not preferable because the shift lens group becomes large. Further, it is not preferable because coma aberration and curvature of field cannot be sufficiently corrected.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to −3.27 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (5) to −2.84 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to −2.41 or more.

In the zoom lens according to the present application, it is preferable that the plurality of lens components in the second-a partial lens group have a positive refractive power. With this configuration, it is possible to suppress spherical aberration, coma aberration, and field curvature that occur in each of the plurality of lens components.
In the zoom lens of the present application, it is desirable that the first lens group has a negative refractive power. This configuration is preferable because the overall length of the zoom lens can be reduced. Further, it is preferable because various aberrations such as spherical aberration can be corrected satisfactorily.
In the zoom lens of the present application, it is desirable that the second lens group has a positive refractive power. This configuration is preferable because spherical aberration and curvature of field can be corrected satisfactorily.
In the zoom lens of the present application, the first lens group has a negative refractive power, the second a partial lens group has a positive refractive power, and the second b partial lens group has a negative refractive power. It is desirable. With this configuration, it is possible to suppress aberrations that occur in the first lens group and the second b partial lens group.

The optical device of the present application includes the zoom lens having the above-described configuration. Thereby, an optical device having a small size and excellent optical performance can be realized.
The zoom lens manufacturing method of the present application is a zoom lens manufacturing method having a first lens group and a second lens group in order from the most object side, and the second lens group is in order from the object side. The second-a partial lens group includes a second-b partial lens group, the second-a partial lens group includes a plurality of lens components having the same sign of refractive power, and the second-b partial lens group includes the second-a partial lens. A lens component having a refractive power having a sign different from the sign of the refractive power of the plurality of lens components in the lens group is provided closest to the object side, and the second a partial lens group and the second b partial lens group have the following conditional expressions ( 1) is satisfied, and when changing the magnification from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is changed.
(1) 0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens The distance on the optical axis from the object-side lens surface of the lens component located closest to the object side to the image-side lens surface of the lens component located closest to the image side in the lens group. A zoom lens having optical performance can be manufactured.

Hereinafter, zoom lenses according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a configuration of a zoom lens according to Example 1 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.
The first lens group G1, in order from the object side, includes a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a positive meniscus lens L13 having a convex surface directed toward the object side. And a positive meniscus lens L14 having a convex surface directed toward the object side. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

The second lens group G2 includes, in order from the object side, a second a partial lens group G2a having a positive refractive power and a second b partial lens group G2b having a negative refractive power.
In order from the object side, the second-a partial lens group G2a has a cemented positive lens composed of a negative meniscus lens L21 having a convex surface directed toward the object side and a positive meniscus lens L22 having a convex surface directed toward the object side, and a convex surface directed toward the object side. It consists of a positive meniscus lens L23, an aperture stop S, a positive lens L24 having a biconvex shape, and a cemented positive lens of a negative meniscus lens L25 having a concave surface facing the object side. The negative meniscus lens L21 is an aspheric lens in which an aspheric surface is formed on the object side lens surface. The positive meniscus lens L23 is an aspheric lens in which an aspheric surface is formed on the object side lens surface.
The second-b partial lens group G2b includes, in order from the object side, only a cemented negative lens including a biconcave negative lens L26 and a biconvex positive lens L27. The biconvex positive lens L27 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

In the zoom lens according to the present embodiment, the first lens group G1 and the first lens group G1 are arranged so that the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction.
Further, in the zoom lens according to the present embodiment, by moving the cemented positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 in the 2a partial lens group G2a toward the image side as a focusing lens group, Focusing to a distance object is performed.
In the zoom lens according to the present exemplary embodiment, the cemented positive lens of the positive lens L24 and the negative meniscus lens L25 in the 2a partial lens group G2a is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thus, image blur correction is performed.

Table 1 below lists values of specifications of the zoom lens according to the present example.
In Table 1, f indicates the focal length, and BF indicates the back focus.
In [Surface data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, nd is the refractive index with respect to the d-line (wavelength λ = 587.6 nm), νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). The object surface is the object surface, the variable is the variable surface interval, the (aperture S) is the aperture stop S, the (aperture FS1) is the first flare cut aperture FS1, the (aperture FS2) is the second flare cut aperture FS2, and the image plane. Indicates the image plane I, respectively. The radius of curvature r = ∞ indicates a plane, and the description of the refractive index nd of air = 1.000 is omitted. When the lens surface is an aspheric surface, the surface number is marked with * and the paraxial radius of curvature is shown in the column of the radius of curvature r.

[Aspherical data] shows the paraxial radius of curvature, conic constant, and aspherical coefficient when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
S (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
+ C4 × y ⁴ + C6 × y ⁶ + C8 × y ⁸ + C10 × y ¹⁰
Here, y is the height in the direction perpendicular to the optical axis, S (y) is the distance (sag amount) along the optical axis from the tangent plane of each aspheric surface at the height y to each aspheric surface, r Is the radius of curvature of the reference sphere (paraxial radius of curvature), κ is the conic constant, and Cn (n is an integer) is the nth-order aspherical coefficient. The secondary aspheric coefficient C2 is zero. “E−n” (n: integer) represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “1.234 × 10 ⁻⁵ ”.

In [Various data], FNO is the F number, 2ω is the angle of view, Y is the image height, TL is the total length of the optical system, di (i: integer) is the variable surface distance of the i-th surface, d0 is the first surface from the object Each distance is shown. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.
Here, “mm” is generally used as a unit of the focal length f, the radius of curvature r, and other lengths listed in Table 1. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
1 18.4021 1.3000 1.851348 40.10
* 2 9.4660 5.1881
3 106.6621 1.0000 1.882997 40.76
4 12.4920 1.7530
5 18.3528 1.7749 1.846660 23.78
6 28.9480 0.6457
7 17.1399 2.0751 1.808090 22.79
8 32.7787 Variable * 9 15.0062 0.8000 1.834410 37.28
10 9.9310 1.7000 1.741000 52.67
11 36.5917 Variable * 12 20.2806 1.2433 1.589130 61.25
13 519.9944 0.8000
14 (Aperture S) ∞ 1.0000
15 33.1718 2.0873 1.617200 54.01
16 -13.7000 1.0000 1.740769 27.78
17 -47.2996 1.8086
18 -12.0144 0.8000 1.834000 37.16
19 10.7146 3.3683 1.730766 40.50
* 20 -14.3627 BF
Image plane ∞

[Aspherical data]
Surface number κ C4 C6 C8 C10
2 -0.8688 2.24260E-04 -1.18580E-07 2.08650E-09 0.00000E + 00
9 1.5382 -4.34140E-05 1.85070E-08 -3.18730E-08 9.22250E-10
12 1.0000 6.95110E-05 8.09320E-07 -2.75250E-09 0.00000E + 00
20 1.0000 7.53770E-05 6.63130E-07 0.00000E + 00 0.00000E + 00

[Various data]
Scaling ratio 2.825
W M T
f 10.3 17.3 29.1
FNO 3.57 4.27 5.80
2ω 79.56 51.30 31.64
Y 8.25 8.25 8.25
TL 74.59 69.93 76.27
BF 19.74 28.12 42.24

<Interval data when focusing on an object at infinity>
W M T
f 10.30000 17.30000 29.10000
d8 22.27046 9.23047 1.45000
d11 4.2370 4.2370 4.2370
BF 19.73960 28.11827 42.24230

<Interval data when focusing on a short distance object (when shooting magnification is -0.01x)>
W M T
d0 1008.7799 1711.7323 2893.5651
f 10.30000 17.30000 29.10000
d8 22.56436 9.39160 1.55387
d11 3.94313 4.07590 4.13316
BF 19.73960 28.11827 42.24230

[Lens group data]
Group start surface f
1 1 -16.653
2 9 19.933
2a 9 15.032
2b 18 -52.447

[Conditional expression values]
(1) Σ2a / Σ2b = 3.087
(2) | fa / fb | = 0.287
(3) | fw / ff | = 0.284
(4) | fγw | = 0.351
(5) ff / fs = 0.906

2 (a), 2 (b), and 2 (c) respectively show the infinite object combination in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens according to Example 1 of the present application. FIG. 5 is a diagram showing various aberrations during focusing.
3 (a), 3 (b), and 3 (c) respectively show short-distance object alignments in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 1 of the present application. FIG. 5 is a diagram showing various aberrations during focusing (when the imaging magnification is -0.01 times).
FIGS. 4A and 4B are lateral aberration diagrams of the zoom lens according to Example 1 of the present application at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state, respectively.

2A to 4B, FNO is an F number, NA is a numerical aperture, A is a half angle of view, and H0 is an object height. D represents the d-line (λ = 587.6 nm) and g represents the g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line represents the sagittal image plane and the broken line represents the meridional image plane. Note that the same reference numerals as in this example are also used in the aberration diagrams of the examples shown below.
From the various aberration diagrams, the zoom lens according to the present embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent imaging at the time of lens shift. It turns out that it has performance.

(Second embodiment)
FIG. 5 is a cross-sectional view showing a configuration of a zoom lens according to Example 2 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.
The first lens group G1, in order from the object side, includes a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a positive meniscus lens L13 having a convex surface directed toward the object side. And a positive meniscus lens L14 having a convex surface directed toward the object side. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

The second lens group G2 includes, in order from the object side, a second a partial lens group G2a having a positive refractive power and a second b partial lens group G2b having a negative refractive power.
The second-a partial lens group G2a includes, in order from the object side, a cemented positive lens including a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side, an aperture stop S, and a biconvex lens. It consists of a positive lens L23 having a shape, a cemented positive lens composed of a biconvex positive lens L24 and a negative meniscus lens L25 having a concave surface facing the object side. The negative meniscus lens L21 is an aspheric lens in which an aspheric surface is formed on the object side lens surface.
The second-b partial lens group G2b includes, in order from the object side, a cemented negative lens of a biconcave negative lens L26 and a positive meniscus lens L27 having a convex surface facing the object side, and a positive meniscus lens L28 having a concave surface facing the object side. It consists of. The positive meniscus lens L28 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

In the zoom lens according to the present embodiment, the first lens group G1 and the first lens group G1 are arranged so that the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction.
Further, in the zoom lens according to the present embodiment, by moving the cemented positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 in the 2a partial lens group G2a toward the image side as a focusing lens group, Focusing to a distance object is performed.
In the zoom lens according to the present exemplary embodiment, the cemented positive lens of the positive lens L24 and the negative meniscus lens L25 in the 2a partial lens group G2a is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thus, image blur correction is performed.
Table 2 below lists values of specifications of the zoom lens according to the present example.

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞
1 21.7269 1.3000 1.851348 40.10
* 2 9.4719 5.7500
3 111.4840 1.0000 1.882997 40.76
4 14.9963 1.9500
5 22.3090 2.0000 1.846660 23.78
6 33.1016 0.2000
7 18.7069 2.0000 1.808090 22.79
8 43.2782 Variable * 9 15.0616 0.8000 1.834410 37.28
10 9.5077 2.0000 1.729157 54.66
11 32.9673 Variable
12 (Aperture S) ∞ 1.8500
13 34.6096 1.5500 1.487490 70.45
14 -34.6096 1.5000
15 27.5396 1.8500 1.617200 54.01
16 -19.7960 1.0000 1.755199 27.51
17 -77.6432 1.8000
18 -73.1879 0.8000 1.806100 40.94
19 14.1510 1.3000 1.677900 55.40
20 36.2665 1.1500
21 -64.5797 1.1500 1.730770 40.51
* 22 -30.4612 BF
Image plane ∞

[Aspherical data]
Surface number κ C4 C6 C8 C10
2 0.4886 1.63540E-05 4.58660E-07 -4.87000E-09 3.86610E-11
9 1.0000 -2.12610E-05 -1.64030E-07 0.00000E + 00 0.00000E + 00
22 4.0626 8.23580E-05 4.98300E-07 -3.25370E-09 0.00000E + 00

[Various data]
Scaling ratio 2.825
W M T
f 10.3 17.3 29.1
FNO 3.59 4.33 5.80
2ω 79.82 51.28 31.62
Y 8.22 8.22 8.22
TL 77.52 72.08 77.92
BF 18.51 26.86 40.93

<Interval data when focusing on an object at infinity>
W M T
f 10.30001 17.29999 29.09994
d8 23.30172 9.51054 1.28187
d11 4.75728 4.75728 4.75728
BF 18.51046 26.85868 40.93132

<Interval data when focusing on a short distance object (when shooting magnification is -0.01x)>
W M T
d0 1010.1167 1712.4939 2894.2034
f 10.30001 17.29999 29.09994
d8 23.59826 9.68431 1.39657
d11 4.46074 4.58351 4.64257
BF 18.51046 26.85868 40.93135

[Lens group data]
Group start surface f
1 1 -17.157
2 9 20.462
2a 9 16.311
2b 18 -40.208

[Conditional expression values]
(1) Σ2a / Σ2b = 3.479
(2) | fa / fb | = 0.406
(3) | fw / ff | = 0.249
(4) | fγw | = 0.348
(5) ff / fs = 1.04

6 (a), 6 (b), and 6 (c) respectively show the infinite object combination in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens according to the second embodiment of the present application. FIG. 5 is a diagram showing various aberrations during focusing.
FIGS. 7 (a), 7 (b), and 7 (c) respectively show short-distance object alignments in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 2 of the present application. FIG. 5 is a diagram showing various aberrations during focusing (when the imaging magnification is -0.01 times).
FIGS. 8A and 8B are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively.
From the various aberration diagrams, the zoom lens according to the present embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent imaging at the time of lens shift. It turns out that it has performance.

(Third embodiment)
FIG. 9 is a cross-sectional view showing a configuration of a zoom lens according to Example 3 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.
The first lens group G1, in order from the object side, includes a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a positive meniscus lens L13 having a convex surface directed toward the object side. And a positive meniscus lens L14 having a convex surface directed toward the object side. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

The second lens group G2 includes, in order from the object side, a second a partial lens group G2a having a positive refractive power and a second b partial lens group G2b having a negative refractive power.
The second-a partial lens group G2a includes, in order from the object side, a cemented positive lens including a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side, an aperture stop S, and a biconvex lens. It consists of a positive lens L23 having a shape, a cemented positive lens composed of a biconvex positive lens L24 and a negative meniscus lens L25 having a concave surface facing the object side. The negative meniscus lens L21 is an aspheric lens in which an aspheric surface is formed on the object side lens surface.
The second-b partial lens group G2b includes, in order from the object side, a cemented negative lens of a biconcave negative lens L26 and a positive meniscus lens L27 having a convex surface facing the object side, and a positive meniscus lens L28 having a concave surface facing the object side. It consists of. The positive meniscus lens L28 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

In the zoom lens according to the present embodiment, the first lens group G1 and the first lens group G1 are arranged so that the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction.
Further, in the zoom lens according to the present embodiment, by moving the cemented positive lens of the negative meniscus lens L21 and the positive meniscus lens L22 in the 2a partial lens group G2a toward the image side as a focusing lens group, Focusing to a distance object is performed.
In the zoom lens according to the present exemplary embodiment, the cemented positive lens of the positive lens L24 and the negative meniscus lens L25 in the 2a partial lens group G2a is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thus, image blur correction is performed.
Table 3 below provides values of specifications of the zoom lens according to the present example.

(Table 3) Third Example
[Surface data]
Surface number r d nd νd
Object ∞
1 21.7269 1.3000 1.851348 40.10
* 2 9.4719 5.7500
3 111.4840 1.0000 1.882997 40.76
4 14.9963 1.9500
5 22.2590 1.9000 1.846660 23.78
6 33.3223 0.2000
7 18.7069 2.1000 1.808090 22.79
8 42.8001 Variable * 9 15.0616 0.8000 1.834410 37.28
10 9.5077 2.0000 1.729157 54.66
11 32.9673 Variable
12 (Aperture S) ∞ 1.8500
13 34.6096 1.5500 1.487490 70.45
14 -34.6096 1.4500
15 27.0404 2.0000 1.583130 59.38
16 -17.0002 1.0000 1.688930 31.06
17 -70.6449 1.8000
18 -73.1879 0.8000 1.806100 40.94
19 14.1510 1.3000 1.677900 55.40
20 36.2665 1.1500
21 -64.5797 1.1500 1.730770 40.51
* 22 -30.4612 BF
Image plane ∞

[Aspherical data]
Surface number κ C4 C6 C8 C10
2 0.4886 1.63540E-05 4.58660E-07 -4.89000E-09 3.86610E-11
9 1.0000 -2.17000E-05 -1.55000E-07 0.00000E + 00 0.00000E + 00
22 4.0626 8.23580E-05 4.98300E-07 -3.25370E-09 0.00000E + 00

[Various data]
Scaling ratio 2.825
W M T
f 10.3 17.3 29.1
FNO 3.59 4.33 5.80
2ω 79.76 51.26 31.60
Y 8.22 8.22 8.22
TL 77.50 72.05 77.87
BF 18.37 26.70 40.75

<Interval data when focusing on an object at infinity>
W M T
f 10.29998 17.29997 29.09996
d8 23.32950 9.54740 1.32415
d11 4.74745 4.74745 4.74745
BF 18.36848 26.70133 40.74813

<Interval data when focusing on a short distance object (when shooting magnification is -0.01x)>
W M T
d0 1010.0819 1712.5230 2894.2416
f 10.29998 17.29997 29.09996
d8 23.62641 9.72135 1.43894
d11 4.45054 4.57350 4.63266
BF 18.36848 26.70133 40.74814

[Lens group data]
Group start surface f
1 1 -17.167
2 9 20.436
2a 9 16.330
2b 18 -40.208

[Conditional expression values]
(1) Σ2a / Σ2b = 3.499
(2) | fa / fb | = 0.406
(3) | fw / ff | = 0.249
(4) | fγw | = 0.347
(5) ff / fs = 1.031

FIGS. 10 (a), 10 (b), and 10 (c) respectively show the infinite object combination in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens according to Example 3 of the present application. FIG. 5 is a diagram showing various aberrations during focusing.
FIGS. 11 (a), 11 (b), and 11 (c) respectively show short-distance objects in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to the third example of the present application. FIG. 5 is a diagram showing various aberrations during focusing (when the imaging magnification is -0.01 times).
FIGS. 12A and 12B are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 3 of the present application, respectively.
From the various aberration diagrams, the zoom lens according to the present embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent imaging at the time of lens shift. It turns out that it has performance.

(Fourth embodiment)
FIG. 13 is a sectional view showing the structure of a zoom lens according to Example 4 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power.
The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The negative meniscus lens L11 is an aspheric lens in which aspheric surfaces are formed on both lens surfaces. The biconcave negative lens L12 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

The second lens group G2 includes, in order from the object side, a second a partial lens group G2a having a positive refractive power and a second b partial lens group G2b having a negative refractive power.
In order from the object side, the second-a partial lens group G2a includes a positive meniscus lens L21 having a convex surface directed toward the object side, an aperture stop S, a biconvex positive lens L22, and a negative meniscus lens L23 having a concave surface directed toward the object side. A positive meniscus lens L26 having a convex surface facing the object side, a positive meniscus lens L26 having a convex surface facing the image side, and a positive meniscus lens L26 having a convex surface facing the image side.
The second b partial lens group G2b comprises solely a negative meniscus lens L27 having a convex surface directed toward the image side. The negative meniscus lens L27 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

In the zoom lens according to the present embodiment, the first lens group G1 and the first lens group G1 are arranged so that the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction.
In the zoom lens according to the present embodiment, the positive meniscus lens L21 in the 2a partial lens group G2a is moved to the image side as the focusing lens group, thereby focusing from an object at infinity to a near object.
In the zoom lens according to the present embodiment, the cemented positive lens of the negative meniscus lens L24 and the positive lens L25 in the 2a partial lens group G2a is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thus, image blur correction is performed.
Table 4 below lists values of specifications of the zoom lens according to the present example.

(Table 4) Fourth Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1 65.6582 1.8000 1.768020 49.23
* 2 11.1606 10.6000
3 -41.8065 3.2000 1.768020 49.23
* 4 17.5136 3.8000
5 14.4408 2.3000 1.922860 20.88
6 23.0940 Variable
7 13.2190 1.5000 1.754999 52.32
8 37.9290 Variable
9 (Aperture S) ∞ 1.5000
10 21.6826 6.5000 1.497820 82.56
11 -9.3713 1.0000 1.883000 40.77
12 -50.0183 1.4211
13 11.9486 1.2000 1.903660 31.31
14 7.9899 2.5000 1.497820 82.56
15 -409.7597 1.2528
16 -5817.7134 1.8000 1.497820 82.56
17 -17.3100 0.4000
18 -13.7854 1.2000 1.768020 49.23
* 19 -21.3255 BF
Image plane ∞

[Aspherical data]
Surface number κ C4 C6 C8 C10
1 11.2695 6.52080E-06 4.51110E-09 0.00000E + 00 0.00000E + 00
2 -0.6591 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
4 2.7380 1.54320E-04 3.81860E-07 0.00000E + 00 0.00000E + 00
19 -21.6774 -1.35420E-04 5.07390E-06 -6.22800E-08 0.00000E + 00

[Various data]
Scaling ratio 1.828
W M T
f 6.90 9.50 12.61
FNO 3.62 4.52 5.77
2ω 98.83 79.61 63.97
Y 7.962 7.962 7.962
TL 70.23 68.58 69.98
BF 14.66 19.26 24.75

<Interval data when focusing on an object at infinity>
W M T
f 6.90000 9.50000 12.61000
d6 11.99855 5.74872 1.65810
d8 1.59738 1.59738 1.59738
BF 14.66442 19.25604 24.74833

<Interval data when focusing on a short distance object (when shooting magnification is -0.01x)>
W M T
d0 675.3095 936.2195 1247.7556
f 6.90000 9.50000 12.61000
d6 12.14042 5.84296 1.72955
d8 1.45551 1.50314 1.52593
BF 14.66442 19.25605 24.74834

[Lens group data]
Group start surface f
1 1 -9.446
2 7 16.681
2a 7 15.399
2b 18 -54.536

[Conditional expression values]
(1) Σ2a / Σ2b = 16.893
(2) | fa / fb | = 0.282
(3) | fw / ff | = 0.263
(4) | fγw | = 0.487
(5) ff / fs = 0.743

FIGS. 14 (a), 14 (b), and 14 (c) respectively show infinite objects in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 4 of the present application. FIG. 5 is a diagram showing various aberrations during focusing.
15 (a), 15 (b), and 15 (c) respectively show short-distance object alignments in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 4 of the present application. FIG. 5 is a diagram showing various aberrations during focusing (when the imaging magnification is -0.01 times).
FIGS. 16A and 16B are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 4 of the present application, respectively.
From the various aberration diagrams, the zoom lens according to the present embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent imaging at the time of lens shift. It turns out that it has performance.

(5th Example)
FIG. 17 is a cross-sectional view showing a configuration of a zoom lens according to Example 5 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. And G3.
The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The negative meniscus lens L11 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

The second lens group G2 includes, in order from the object side, a second a partial lens group G2a having a positive refractive power and a second b partial lens group G2b having a negative refractive power.
The second-a partial lens group G2a includes, in order from the object side, a cemented positive lens of a negative meniscus lens L21 having a convex surface directed toward the object side and a biconvex positive lens L22, a first flare-cut stop FS1, and an object side. The lens comprises a positive meniscus lens L23 having a convex surface and an aperture stop S.
The second-b partial lens group G2b includes, in order from the object side, a cemented negative lens of a positive meniscus lens L24 having a concave surface facing the object side and a biconcave negative lens L25, and a second flare-cut stop FS2. The positive meniscus lens L24 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.
The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, and a cemented positive lens composed of a negative meniscus lens L32 having a convex surface facing the object side and a biconvex positive lens L33. The positive lens L31 is an aspheric lens in which an aspheric surface is formed on the image side lens surface.

In the zoom lens according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state, and the second lens group G2 and the third lens. The first lens group G1, the second lens group G2, and the third lens group G3 move in the optical axis direction so that the air gap with the group G3 decreases.
Further, in the zoom lens according to the present embodiment, by moving the cemented positive lens of the negative meniscus lens L21 and the positive lens L22 in the 2a partial lens group G2a toward the image side as a focusing lens group, a short distance from an object at infinity. Focusing on the object is performed.
In the zoom lens according to the present embodiment, the cemented negative lens of the positive meniscus lens L24 and the negative lens L25 in the 2b partial lens group G2b is moved as a shift lens group so as to include a component in a direction orthogonal to the optical axis. Thus, image blur correction is performed.
Table 5 below provides values of specifications of the zoom lens according to the present example.

(Table 5) Fifth Example
[Surface data]
Surface number r d nd νd
Object ∞
1 25.0000 1.8000 1.743300 49.32
* 2 8.5722 5.2284
3 -31.9974 0.8000 1.496999 81.54
4 25.7099 0.1500
5 16.2678 2.1558 1.846660 23.78
6 33.0579 Variable
7 27.3560 0.8000 1.795041 28.69
8 12.7778 2.6232 1.603001 65.44
9 -27.7840 Variable
10 (Aperture FS1) ∞ 0.6778
11 10.6214 2.3407 1.603001 65.44
12 28.5797 1.8566
13 (Aperture S) ∞ 1.0996
* 14 -27.4165 1.3691 1.821145 24.06
15 -17.0648 0.8000 1.754998 52.32
16 21.3149 0.5500
17 (Aperture FS2) ∞ Variable
18 18.9858 2.0521 1.677900 54.89
* 19 -30.4460 0.1500
20 155.5536 0.8000 1.850 260 32.35
21 12.8042 2.3802 1.603001 65.44
22 -74.1840 BF
Image plane ∞

[Aspherical data]
Surface number κ C4 C6 C8 C10
2 0.8028 -2.11830E-06 -2.66050E-09 1.19660E-09 -3.08550E-11
14 -7.4148 2.77450E-05 -2.03840E-06 2.71760E-07 -9.60030E-09
19 0.2983 1.58800E-04 1.88510E-06 -5.09710E-08 8.84260E-10

[Various data]
Scaling ratio 2.825
W M T
f 10.3 18.7 29.1
FNO 3.64 4.23 5.86
2ω 78.78 46.56 30.67
Y 7.962 7.962 7.962
TL 66.55 62.74 68.78
BF 15.48 25.28 36.78

<Interval data when focusing on an object at infinity>
W M T
f 10.30000 18.74998 29.09995
d6 17.86509 5.84890 1.00000
d9 2.36528 2.36528 2.36528
d17 3.20972 1.61399 1.00000
BF 15.48011 25.28115 36.78476

<Interval data when focusing on a short distance object (when shooting magnification is -0.01x)>
W M T
d0 1006.0724 1855.1767 2891.6589
f 10.30000 18.74998 29.09995
d6 18.13661 5.97474 1.08438
d9 2.09376 2.23944 2.28090
d17 3.20972 1.61399 1.00000
BF 15.48033 25.28137 36.78498

[Lens group data]
Group start surface f
1 1 -15.354
2 7 16.815
2a 7 14.188
2b 14 -15.968
3 18 19.476

[Conditional expression values]
(1) Σ2a / Σ2b = 4.060
(2) | fa / fb | = 0.889
(3) | fw / ff | = 0.381
(4) | fγw | = 0.381
(5) ff / fs = -1.782

FIGS. 18 (a), 18 (b), and 18 (c) respectively show the object at infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the zoom lens according to Example 5 of the present application. FIG. 5 is a diagram showing various aberrations during focusing.
FIGS. 19 (a), 19 (b), and 19 (c) respectively show short-distance object alignments in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 5 of the present application. FIG. 5 is a diagram showing various aberrations during focusing (when the imaging magnification is -0.01 times).
FIGS. 20A and 20B are lateral aberration diagrams at the time of lens shift (± 0.1 mm) in the wide-angle end state and the telephoto end state of the zoom lens according to Example 5 of the present application, respectively.
From the various aberration diagrams, the zoom lens according to the present embodiment has excellent imaging performance by properly correcting various aberrations from the wide-angle end state to the telephoto end state, and also excellent imaging at the time of lens shift. It turns out that it has performance.

According to each of the above-described embodiments, it is possible to realize a zoom lens that is small and has excellent optical performance, has a zoom ratio of about 3 times, and can correct image blur.
The zoom lens according to each of the above embodiments is configured to move a part of the lens components in the second lens group as the focusing lens group. For this reason, the lens weight of the focusing lens group is small, the motor mechanism for driving the focusing lens group can be downsized, and the lens barrel can be downsized.
In the zoom lens according to each of the above embodiments, the lens component disposed closest to the image side has a distance on the optical axis from the image side lens surface to the image plane (back focus) of 10.0 to 30 with the smallest distance. About 0.0 mm is preferable. In the zoom lens according to each of the above embodiments, the image height is preferably 5.0 to 12.5 mm, and more preferably 5.0 to 9.5 mm.

Here, each said Example has shown one specific example of this invention, and this invention is not limited to these.
Note that the following contents can be adopted as appropriate as long as the optical performance of the zoom lens of the present application is not impaired.
As a numerical example of the zoom lens of the present application, a two-group or three-group configuration is shown, but the present application is not limited to this, and a zoom lens of other group configuration (for example, four groups) can also be configured. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image plane side of the zoom lens of the present application may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during zooming.

In addition, the zoom lens of the present application uses a part of a lens group, an entire lens group, or a plurality of lens groups as a focusing lens group in order to perform focusing from a long-distance object to a short-distance object. It is good also as a structure moved to. In particular, it is preferable that at least a part of the second lens group is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor.
In the zoom lens of the present application, either the entire lens group or a part of the lens group is moved so as to include a component perpendicular to the optical axis as a shift lens group, or rotationally moved (oscillated) in an in-plane direction including the optical axis. The image blur caused by camera shake can be corrected by moving the image. In particular, in the zoom lens of the present application, it is preferable that at least a part of the second lens group is a shift lens group.

  The lens surface of the lens constituting the zoom lens of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In the zoom lens of the present application, the aperture stop is preferably disposed in or near the second lens group. However, a lens frame may be used as a substitute for the aperture stop without providing a member.
Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom lens of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.
The zoom lens of the present application has a zoom ratio of about 2 to 7 times.
In the zoom lens of the present application, the first lens group preferably has two positive lens components and two negative lens components. The second lens group preferably has two positive lens components and one negative lens component. Alternatively, the second lens group preferably has three positive lens components and one negative lens component. Alternatively, the second lens group preferably has four positive lens components and one negative lens component. The third lens group preferably has two positive lens components.

Next, a camera equipped with the zoom lens of the present application will be described with reference to FIG.
FIG. 21 is a diagram illustrating a configuration of a camera including the zoom lens of the present application.
The camera 1 is a digital single-lens reflex camera provided with the zoom lens according to the first embodiment as a photographing lens 2.
In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and imaged on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. Thereby, the light from the subject is picked up by the image pickup device 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.
Here, the zoom lens according to the first embodiment mounted as the photographing lens 2 in the camera 1 is small and has excellent optical performance due to its characteristic lens configuration. Thereby, this camera 1 can implement | achieve the outstanding optical performance, aiming at size reduction. Even if the camera having the zoom lens according to the second to fifth embodiments mounted as the taking lens 2 is configured, the same effect as the camera 1 can be obtained. Even when the zoom lens according to each of the above embodiments is mounted on a camera having no quick return mirror 3, the same effect as the camera 1 can be obtained.

Finally, the outline of the manufacturing method of the zoom lens of this application is demonstrated based on FIG.
The zoom lens manufacturing method of the present application is a zoom lens manufacturing method having a first lens group and a second lens group in order from the most object side, and includes the following steps S1 to S3.
Step S1: The second lens group includes, in order from the object side, a 2a partial lens group and a 2b partial lens group. The 2a partial lens group includes a plurality of lens components having the same sign of refractive power. The second-b partial lens group has a lens component having a refractive power having a sign different from that of the refractive power of the plurality of lens components in the second-a partial lens group on the most object side.

Step S2: The 2a partial lens group and the 2b partial lens group satisfy the following conditional expression (1), and the first lens group and the second lens group are sequentially arranged in the lens barrel from the object side.
(1) 0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: in the 2b partial lens group Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side Step S3: By providing a known moving mechanism, the wide angle end When zooming from the state to the telephoto end state, the distance between the first lens group and the second lens group is changed.
According to the zoom lens manufacturing method of the present application, a zoom lens having a small size and excellent optical performance can be manufactured.

G1 1st lens group G2 2nd lens group G2a 2a partial lens group G2b 2b partial lens group G3 3rd lens group S Aperture stop I Image surface W Wide-angle end state M Intermediate focal length state T Telephoto end state

Claims (12)

In order from the most object side, it has a first lens group and a second lens group,
When zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group is changed,
The second lens group includes, in order from the object side, a 2a partial lens group and a 2b partial lens group,
The second-a partial lens group includes a plurality of lens components having the same refractive power sign,
The 2b partial lens group has a lens component having a refractive power with a sign different from the sign of the refractive power of the plurality of lens components in the 2a partial lens group on the most object side,
A zoom lens satisfying the following conditional expression:
0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the group The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <| fa / fb | <2.00
However,
fa: focal length of the 2a partial lens group fb: focal length of the 2b partial lens group   The at least one of the plurality of lens components in the second-a partial lens group is moved in the optical axis direction as a focusing lens group, and focusing from an object at infinity to a near object is performed. The zoom lens according to claim 1 or 2. The zoom lens according to claim 3, wherein the following conditional expression is satisfied.
0.15 <| fw / ff | <0.45
However,
fw: focal length of the zoom lens in the wide-angle end state ff: focal length of the focusing lens group The zoom lens according to claim 3 or 4, wherein the following conditional expression is satisfied.
0.15 <| fγw | <0.60
However,
fγw: an image plane movement coefficient of the focusing lens group in the wide-angle end state   6. The zoom lens according to claim 1, wherein at least a part of the second lens group is moved as a shift lens group so as to include a component in a direction perpendicular to the optical axis. . The zoom lens according to claim 6, wherein the following conditional expression is satisfied.
−3.70 <ff / fs <3.10
However,
ff: focal length of the focusing lens group fs: focal length of the shift lens group   The zoom lens according to any one of claims 1 to 7, wherein the plurality of lens components in the second-a partial lens group have positive refractive power.   The zoom lens according to claim 1, wherein the first lens group has a negative refractive power.   The zoom lens according to any one of claims 1 to 9, wherein the second lens group has a positive refractive power.   An optical apparatus comprising the zoom lens according to any one of claims 1 to 10. A method of manufacturing a zoom lens having a first lens group and a second lens group in order from the most object side,
The second lens group includes, in order from the object side, a second a partial lens group and a second b partial lens group, and the second a partial lens group includes a plurality of lens components having the same refractive power sign, The second-b partial lens group has a lens component having a refractive power of a sign different from a refractive power sign of the plurality of lens components in the second-a partial lens group on the most object side;
The 2a partial lens group and the 2b partial lens group satisfy the following conditional expression:
A zoom lens manufacturing method, wherein the distance between the first lens group and the second lens group is changed when zooming from a wide-angle end state to a telephoto end state.
0.20 <Σ2a / Σ2b <18.00
However,
Σ2a: Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the 2a partial lens group Σ2b: the second 2b partial lens Distance on the optical axis from the object side lens surface of the lens component located closest to the object side to the image side lens surface of the lens component located closest to the image side in the group

Images