JP6205852B2 - Zoom lens, optical device - Google Patents

Description

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

  Conventionally, many so-called negative advanced zoom lenses having a two-group configuration including a lens group having negative refractive power closest to the object side have been proposed (see, for example, Patent Document 1).

JP 2011-107269 A

  However, the conventional zoom lens as described above has a problem that correction of various aberrations is insufficient.

  Accordingly, the present invention has been made in view of the above problems, and provides a high-performance zoom lens in which various aberrations are favorably corrected, an optical device including the zoom lens, and a method for manufacturing the zoom lens. Objective.

In order to solve the above problems, the present invention
In order from the object side, the first lens group having a negative refractive power and a second lens group having a positive refractive power,
The first lens group is composed of one negative lens component and one positive lens component in order from the object side,
The second lens group comprises, in order from the object side, a positive lens component, a cemented positive lens obtained by cementing a negative lens and a positive lens in order from the object side, the cemented negative formed by joining a positive lens and a negative lens in order from the object side A lens,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes,
Provided is a zoom lens that satisfies the following conditional expression.
-2.00 <(r2n1 + r1n1) / (r2n1-r1n1) <0.00
However,
r1n1: radius of curvature of the most object side lens surface in the negative lens component in the first lens group r2n1: radius of curvature of the most image side lens surface in the negative lens component in the first lens group
The lens component means a cemented lens formed by joining two or more lenses or a single lens.

The present invention also provides
An optical apparatus comprising the zoom lens is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the high performance zoom lens which corrected various aberrations favorably, the optical apparatus provided with this zoom lens, and the manufacturing method of this zoom lens can be provided.

FIG. 1 is a cross-sectional view showing the configuration of the zoom lens according to the first embodiment of the present application when focusing on an object at infinity in the wide-angle end state. 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. FIG. 3 is a cross-sectional view showing the configuration of the zoom lens according to the second embodiment of the present application when focusing on an object at infinity in the wide-angle end state. FIGS. 4 (a), 4 (b), and 4 (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. FIG. 5 is a cross-sectional view showing the configuration of the zoom lens according to the third embodiment of the present application when focusing on an object at infinity in the wide-angle end state. 6 (a), 6 (b), and 6 (c) respectively show the infinite object combination 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. FIG. 5 is a diagram showing various aberrations during focusing. FIG. 7 is a diagram illustrating a configuration of a camera including the zoom lens of the present application. FIG. 8 is a diagram showing an outline of the zoom lens manufacturing method of the present application.

Hereinafter, the zoom lens, the optical device, and the zoom lens manufacturing method of the present application will be described.
The zoom lens according to the present application includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. The second lens group includes, in order from the object side, a positive lens component, a cemented positive lens of a negative lens and a positive lens, a positive lens and a negative lens. The distance between the first lens group and the second lens group changes at the time of zooming from the wide-angle end state to the telephoto end state, and the following conditional expression (1) is satisfied. It is characterized by that.
(1) -2.00 <(r2n1 + r1n1) / (r2n1-r1n1) <0.00
However,
r1n1: radius of curvature of the most object side lens surface in the negative lens component in the first lens group r2n1: radius of curvature of the most image side lens surface in the negative lens component in the first lens group

  As described above, the zoom lens of the present application is obtained by improving the negative leading zoom lens including the first lens group having negative refractive power and the second lens group having positive refractive power in order from the object side. . Specifically, the zoom lens of the present application is a lens in which spherical aberration, coma aberration, and astigmatism are favorably corrected while downsizing without increasing the number of lenses more than necessary.

Conditional expression (1) is a conditional expression that defines the form factor (q factor) of the negative lens component located closest to the object side in the first lens group. Conditional expression (1) indicates that the negative lens component has a meniscus shape that satisfies the condition of | r1n1 | = 3 | r2n1 | through a biconcave shape to a plano-concave shape. The zoom lens of the present application can satisfactorily correct field curvature, astigmatism, distortion and coma in the wide-angle end state by satisfying conditional expression (1).
Here, in the present application, the “lens component” refers to a cemented lens or a single lens formed by cementing two or more lenses. It should be noted that the composite aspherical lens shown in each example of the present application to be described later is treated as a single lens because the resin layer cannot exist independently as an optical system due to the property of molding a resin layer on a glass lens. Shall.

  When the corresponding value of the conditional expression (1) of the zoom lens of the present application exceeds the upper limit value, the absolute value of the radius of curvature of the lens surface closest to the object side in the negative lens component in the first lens group is larger than the lens surface closest to the image side. Becomes smaller. In this case, astigmatism and distortion are deteriorated, which is not preferable. If the upper limit value of conditional expression (1) is set to −0.10, it is preferable because the above-described correction of various aberrations is advantageous. Moreover, if the upper limit of conditional expression (1) is set to -0.50, it is more preferable because the effect of the present application can be maximized.

On the other hand, when the corresponding value of conditional expression (1) of the zoom lens of the present application is below the lower limit value, the radius of curvature of the lens surface closest to the object side in the negative lens component in the first lens group is the curvature of the lens surface closest to the image side. The value becomes close to the radius, and as a result, the refractive power decreases. Such a decrease in the negative refractive power of the negative lens component leads to an increase in the size of the zoom lens of the present application and an increase in the filter size. From the viewpoint of aberration correction, if the zoom lens of the present application is forcibly reduced in size, not only off-axis aberrations but also spherical aberrations in the telephoto end state are deteriorated. If the lower limit value of conditional expression (1) is set to −1.80, it is preferable because the above-described correction of various aberrations is advantageous. Moreover, if the lower limit value of conditional expression (1) is set to −1.50, it is more preferable because the effect of the present application can be maximized.
With the above configuration, a high-performance zoom lens in which various aberrations are favorably corrected can be realized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 0.00 <(r2n3-r1n3) / (r2n3 + r1n3) <1.00
However,
r1n3: radius of curvature of the lens surface closest to the object side in the cemented negative lens in the second lens group r2n3: radius of curvature of the lens surface closest to the image side in the cemented negative lens in the second lens group

  Conditional expression (2) is a conditional expression that defines the reciprocal of the form factor (q factor) of the cemented negative lens in the second lens group. Conditional expression (2) means that the radius of curvature of the lens surface closest to the object side in the cemented negative lens and the radius of curvature of the lens surface closest to the image side are close to each other. When the value of conditional expression (2) is 1.00, the cemented negative lens has a plano-concave shape. The zoom lens of the present application can satisfactorily correct spherical aberration, astigmatism, and spherical aberration and coma in the telephoto end state by satisfying conditional expression (2).

  When the corresponding value of conditional expression (2) of the zoom lens of the present application exceeds the upper limit value, the cemented negative lens in the second lens group becomes a biconcave shape. In this case, spherical aberration and astigmatism are deteriorated as a result, which is not preferable. It is preferable to set the upper limit of conditional expression (2) to 0.80 because the above-described correction of various aberrations is advantageous. Further, if the upper limit value of conditional expression (2) is 0.70, it is more preferable because the effect of the present application can be maximized.

  On the other hand, when the corresponding value of the conditional expression (2) of the zoom lens of the present application is lower than the lower limit value, the curvature radius of the most object side lens surface and the curvature of the most image side lens surface in the cemented negative lens in the second lens group. The radius becomes a closer value, and as a result, the refractive power of the cemented negative lens decreases. Finally, the direction of the shape of the cemented negative lens is reversed. Decreasing the refractive power of the cemented negative lens is not preferable because it causes deterioration of spherical aberration and coma particularly in the telephoto end state. It is preferable to set the lower limit of conditional expression (2) to 0.05 because the above-described correction of various aberrations is advantageous. Moreover, if the lower limit value of conditional expression (2) is 0.10, it is more preferable because the effects of the present application can be maximized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 0.10 <Bfw / D2 <1.50
However,
Bfw: Back focus of the zoom lens in the wide-angle end state (when an optical low-pass filter or a dummy glass equivalent thereto is disposed in the zoom lens, the back focus in a state in which these are removed, that is, the air conversion back focus)
D2: Total thickness of the second lens group

  Conditional expression (3) represents the back focus of the zoom lens of the present application and the total thickness of the second lens unit, that is, the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side in the second lens unit. Is a conditional expression that prescribes the relationship between The zoom lens of the present application can satisfactorily correct various aberrations such as coma and astigmatism while achieving miniaturization by satisfying conditional expression (3).

  When the corresponding value of the conditional expression (3) of the zoom lens of the present application exceeds the upper limit value, the total thickness of the second lens group becomes significantly smaller than the back focus. In this case, as a result, the refractive power of the second lens group becomes large, and spherical aberration, coma aberration, and astigmatism are deteriorated. If the upper limit value of conditional expression (3) is 1.20, it is preferable because the above-described correction of various aberrations is advantageous. Moreover, if the upper limit of conditional expression (3) is set to 1.00, it is more preferable because the effects of the present application can be maximized.

  On the other hand, when the corresponding value of the conditional expression (3) of the zoom lens of the present application is below the lower limit value, the total thickness of the second lens group becomes significantly larger than the back focus. In this case, the entire length of the zoom lens of the present application is increased, which is not preferable. Further, if the zoom lens of the present application is to be forcibly reduced in size, the refractive power of the first lens group must be increased, resulting in deterioration in astigmatism and field curvature. Note that it is preferable to set the lower limit value of conditional expression (3) to 0.20 because it is advantageous to correct various aberrations such as coma and astigmatism. Moreover, if the lower limit of conditional expression (3) is 0.25, the effect of the present application can be maximized, which is more preferable.

  In the zoom lens of the present application, the second lens group is disposed adjacent to the object side of the negative lens component and the meniscus-shaped negative lens component with the concave surface facing the object side, which is disposed closest to the image side. It is desirable to further have a positive lens component. Note that “a meniscus negative lens component having a concave surface facing the object side” means that when the negative lens component is a cemented lens, the lens surface closest to the object side is concave and the lens surface closest to the image side Means a cemented negative lens having a convex surface. With the above configuration, the overall length of the zoom lens of the present application is reduced, and the size can be reduced. Also, from the viewpoint of aberration correction, coma, astigmatism and curvature of field are excellent by combining a meniscus negative lens component and a positive lens component that are arranged closest to the image side and have a concave surface facing the object side. Can be corrected.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (4).
(4) 0.10 <D2r / Bfw <2.00
However,
D2r: Distance between the negative lens component in the second lens group and the positive lens component arranged adjacent to the object side Bfw: Back focus of the zoom lens in the wide-angle end state (optical low-pass in the zoom lens) When a filter or a dummy glass equivalent thereto is arranged, the back focus in a state in which these are removed, that is, the air equivalent back focus)

  Conditional expression (4) is a conditional expression that prescribes an optimum air gap between the negative lens component in the second lens group and the positive lens component arranged adjacent to the object side. The zoom lens of the present application can satisfactorily correct astigmatism, field curvature, coma aberration, and spherical aberration by satisfying conditional expression (4).

  When the corresponding value of the conditional expression (4) of the zoom lens of the present application exceeds the upper limit value, the air interval becomes significantly larger than the back focus. In this case, the diameter of the negative lens component in the second lens group becomes remarkably large, and when the zoom lens of the present application is applied to the camera, the negative lens component will not fit inside the camera. Further, from the viewpoint of aberration correction, the negative lens component only has an effect of correcting curvature of field, that is, an effect as a so-called field flattener, so that the correction effect of coma aberration and spherical aberration is reduced, which is preferable. Absent. If the upper limit value of conditional expression (4) is 1.50, it is preferable because the above-described correction of various aberrations is advantageous. Moreover, if the upper limit of conditional expression (4) is 1.20, it is more preferable because the effects of the present application can be maximized.

  On the other hand, when the corresponding value of the conditional expression (4) of the zoom lens of the present application is less than the lower limit value, the air interval becomes significantly smaller than the back focus. In this case, the effect of correcting the off-axis aberration due to the negative lens component in the second lens group is reduced, and the effect as a field flattener is also reduced. For this reason, astigmatism and field curvature correction effects are reduced as a result, which is not preferable. Further, since the back focus becomes large, it is not preferable from the viewpoint of miniaturization of the zoom lens of the present application. If the lower limit of conditional expression (4) is set to 0.11, it is preferable because the above-described correction of various aberrations is advantageous. Moreover, if the lower limit of conditional expression (4) is set to 0.15, it is more preferable because the effect of the present application can be maximized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (5).
(5) 0.20 <f2 / ft <0.65
However,
ft: focal length of the zoom lens in the telephoto end state f2: focal length of the second lens group

  Conditional expression (5) is a conditional expression that defines the focal length of the second lens group, in other words, the optimum refractive power of the second lens group. By satisfying conditional expression (5), the zoom lens of the present application can satisfactorily correct spherical aberration, coma aberration, astigmatism and the like while preventing an increase in size of the zoom lens of the present application.

  When the corresponding value of the conditional expression (5) of the zoom lens of the present application exceeds the upper limit value, the refractive power of the second lens group becomes significantly small. In this case, the zoom lens of the present application is enlarged. Therefore, if it is attempted to reduce the size of the zoom lens of the present application, the refractive power of the first lens group must be remarkably increased. As a result, astigmatism, coma, and the like deteriorate, which is not preferable. Note that it is preferable to set the upper limit of conditional expression (5) to 0.58 because the correction of various aberrations described above becomes advantageous. Moreover, if the upper limit of conditional expression (5) is set to 0.55, it is more preferable because the effects of the present application can be maximized.

  On the other hand, when the corresponding value of the conditional expression (5) of the zoom lens of the present application is less than the lower limit value, the refractive power of the second lens group is significantly increased. In this case, since spherical aberration, coma aberration, astigmatism and the like deteriorate as a result, it is not preferable. Note that it is preferable to set the lower limit of conditional expression (5) to 0.30 because the above-described correction of various aberrations is advantageous. Moreover, if the lower limit of conditional expression (5) is set to 0.40, it is more preferable because the effect of the present application can be maximized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (6).
(6) 0.60 <(− f2r) / f2 <2.00
However,
f2r: focal length of the negative lens component in the second lens group f2: focal length of the second lens group

  Conditional expression (6) is a conditional expression that defines the focal length of the negative lens component in the second lens group, in other words, the refractive power of the negative lens component. The zoom lens of the present application can satisfactorily correct field curvature, astigmatism, spherical aberration, and coma aberration by satisfying conditional expression (6).

  When the corresponding value of the conditional expression (6) of the zoom lens of the present application exceeds the upper limit value, the absolute value of the focal length of the negative lens component in the second lens group is significantly increased, and the negative refractive power is decreased. In this case, the effect of shortening the back focus by the negative lens component is reduced, and the effect of correcting curvature of field and astigmatism is also reduced. Note that it is preferable to set the upper limit of conditional expression (6) to 1.80 because the correction of various aberrations described above becomes advantageous. Moreover, if the upper limit of conditional expression (6) is 1.70, it is more preferable because the effect of the present application can be maximized.

  On the other hand, when the corresponding value of the conditional expression (6) of the zoom lens of the present application is below the lower limit value, the absolute value of the focal length of the negative lens component in the second lens group is remarkably reduced, and the negative refractive power is remarkably increased. In this case, since spherical aberration and coma aberration are deteriorated as a result, it is not preferable. In addition, the sensitivity to decentering also increases, that is, it is not preferable because various aberrations are likely to occur when decentering occurs in the lens constituting the zoom lens of the present application due to a manufacturing error or the like. If the lower limit value of conditional expression (6) is 0.70, it is preferable to correct various aberrations such as spherical aberration. Further, if the lower limit value of conditional expression (6) is 0.90, it is more preferable because the effect of the present application can be maximized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (7).
(7) 0.50 <f2p / f2 <2.00
However,
f2p: focal length of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group f2: focal length of the second lens group

  Conditional expression (7) is a conditional expression that defines the focal length of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group, in other words, the refractive power of the positive lens component. The zoom lens of the present application can satisfactorily correct spherical aberration and coma aberration by satisfying conditional expression (7).

  When the corresponding value of conditional expression (7) of the zoom lens of the present application exceeds the upper limit value, the positive refractive power of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group becomes small. This is not preferable because the effect of correcting the spherical aberration is reduced. Note that it is preferable to set the upper limit of conditional expression (7) to 1.70, since correction of various aberrations is advantageous. Moreover, if the upper limit of conditional expression (7) is set to 1.50, it is more preferable because the effect of the present application can be maximized.

  On the other hand, when the corresponding value of conditional expression (7) of the zoom lens of the present application is lower than the lower limit value, the positive refractive power of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group becomes large. Become. In this case, since spherical aberration and coma aberration are deteriorated as a result, it is not preferable. It is preferable to set the lower limit of conditional expression (7) to 0.55 because it is advantageous to correct various aberrations such as spherical aberration. Moreover, if the lower limit value of conditional expression (7) is 0.60, it is more preferable because the effect of the present application can be maximized.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (8).
(8) 1.00 <(r2r + r1r) / (r2r−r1r) <8.00
However,
r1r: radius of curvature of the lens surface closest to the object in the negative lens component in the second lens group r2r: radius of curvature of the lens surface closest to the image in the negative lens component in the second lens group

  Conditional expression (8) is a conditional expression that defines the shape factor of the negative lens component in the second lens group. Conditional expression (8) basically indicates that the negative lens component has a negative meniscus shape with a concave surface facing the object side. Note that the corresponding value of the conditional expression (8) is that the paraxial radius of curvature of the surface closest to the object in the negative lens component and the most image, regardless of whether the negative lens component is a cemented lens, a single lens, or an aspheric lens. Calculated with the paraxial radius of curvature of the side surface. By satisfying conditional expression (8), the zoom lens of the present application can satisfactorily correct field curvature, astigmatism, and coma while preventing an increase in the size of the zoom lens of the present application.

  When the corresponding value of conditional expression (8) of the zoom lens of the present application exceeds the upper limit value, the difference in the radius of curvature between the lens surface closest to the object side and the lens surface closest to the image side in the negative lens component in the second lens group is It will disappear. That is, the refractive power of the negative lens component becomes small. For this reason, the correction effect of various aberrations by the negative lens component is reduced, and as a result, it becomes impossible to sufficiently correct field curvature and astigmatism. Further, since the negative refractive power behind the second lens group is reduced, the zoom lens of the present application is increased in size, which is not preferable. It is preferable to set the upper limit of conditional expression (8) to 7.00 because the correction of various aberrations described above becomes advantageous. Moreover, if the upper limit of conditional expression (8) is set to 5.00, it is more preferable because the effect of the present application can be maximized.

  On the other hand, when the corresponding value of conditional expression (8) of the zoom lens of the present application is below the lower limit value, the negative lens component in the second lens group becomes a biconcave shape. In this case, coma and astigmatism are deteriorated, which is not preferable. Moreover, since the sensitivity with respect to eccentricity will also become large, it is not preferable. If the lower limit value of conditional expression (8) is 1.50, it is preferable to correct various aberrations such as spherical aberration. Moreover, if the lower limit value of conditional expression (8) is 2.00, it is more preferable because the effect of the present application can be maximized.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (9).
(9) −3.00 <(r2p + r1p) / (r2p−r1p) <0.00
However,
r1p: radius of curvature of the lens surface closest to the object side in the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group r2p: the negative lens component in the second lens group The radius of curvature of the lens surface closest to the image side in the positive lens component arranged adjacent to the object side

  Conditional expression (9) is a conditional expression that defines the shape factor of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group. Conditional expression (9) indicates that the positive lens component has a positive meniscus shape with a concave surface facing the object side, a plano-convex shape with a flat surface facing the object side, or a biconvex shape. The zoom lens of the present application can satisfactorily correct field curvature, astigmatism, and spherical aberration by satisfying conditional expression (9).

  When the corresponding value of the conditional expression (9) of the zoom lens of the present application exceeds the upper limit value, the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group has a stronger convex surface on the object side. The positive lens shape, that is, the positive lens shape in which the lens surface closest to the object side in the positive lens component has a smaller absolute value of the radius of curvature than the lens surface closest to the image side. In this case, field curvature and astigmatism are deteriorated, which is not preferable. Note that it is preferable to set the upper limit of conditional expression (9) to −0.10 because the above-described correction of various aberrations is advantageous. Moreover, if the upper limit of conditional expression (9) is set to -0.30, it is more preferable because the effect of the present application can be maximized.

  On the other hand, when the corresponding value of conditional expression (9) of the zoom lens of the present application is lower than the lower limit value, the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group is included in the positive lens component. Thus, a meniscus shape having a relatively small refractive power and a small difference in radius of curvature between the lens surface closest to the object side and the lens surface closest to the image side is obtained. In this case, since spherical aberration will deteriorate, it is not preferable. If the lower limit value of conditional expression (9) is set to -2.50, it is preferable to correct various aberrations. Moreover, if the lower limit value of conditional expression (9) is set to -2.00, it is more preferable because the effect of the present application can be maximized.

  In addition, it is desirable that the zoom lens of the present application has an aperture stop closer to the image side than the positive lens component arranged closest to the object side in the second lens group. With this configuration, the zoom lens of the present application can satisfactorily correct astigmatism and field curvature.

  In the zoom lens of the present application, it is desirable that the aperture stop is disposed adjacent to the image side of the cemented positive lens in the second lens group. With this configuration, the zoom lens of the present application can satisfactorily correct astigmatism and field curvature.

  In the zoom lens of the present application, it is preferable that the first lens group has at least one aspheric surface. With this configuration, the zoom lens of the present application can satisfactorily correct aberrations with respect to off-axis rays, particularly astigmatism, field curvature, and coma.

  In the zoom lens of the present application, it is desirable that the second lens group has at least one aspheric surface. With this configuration, the zoom lens of the present application can satisfactorily correct coma and spherical aberration.

  The optical apparatus of the present application is characterized by having the zoom lens having the above-described configuration. Thereby, it is possible to realize a high-performance optical device in which various aberrations are favorably corrected.

The zoom lens manufacturing method of the present application is a zoom lens manufacturing method including, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power. One lens group is composed of one negative lens component and one positive lens component in order from the object side, and the second lens group is composed of a positive lens component, a negative lens, and a positive lens in order from the object side. From the wide-angle end state to the telephoto end state so that the first lens group satisfies the following conditional expression (1): It is characterized in that the distance between the first lens group and the second lens group is changed at the time of zooming. Thereby, a high-performance zoom lens in which various aberrations are favorably corrected can be manufactured.
(1) -2.00 <(r2n1 + r1n1) / (r2n1-r1n1) <0.00
However,
r1n1: radius of curvature of the most object side lens surface in the negative lens component in the first lens group r2n1: radius of curvature of the most image side lens surface in the negative lens component in the first lens group

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 diagram showing a lens configuration at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to the first embodiment of the present application, and a movement locus of each lens group at the time of zooming.
The zoom lens according to the present exemplary embodiment includes, in order from the object side along the optical axis, 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 along the optical axis, a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface directed toward the object side. The negative lens L11 is a composite aspherical lens formed by forming a resin layer provided on the image side glass surface into an aspherical shape.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a negative meniscus lens L22 having a convex surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side. A cemented negative lens, an aperture stop S, a cemented negative lens of a thick biconvex positive lens L24 and a biconcave negative lens L25, a biconvex positive lens L26, and a convex surface on the image side. A positive meniscus lens L27 directed to the negative meniscus lens L28 having a convex surface facing the image side. The positive lens L26 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  A dummy glass FL corresponding to an optical low-pass filter is disposed between the second lens group G2 and the image plane I.

  Under the above configuration, in the zoom lens according to the present embodiment, the first lens group G1 and the second lens group G2 change so that the air gap between the first lens group G1 and the second lens group G2 changes during zooming from the wide-angle end state to the telephoto end state. The first lens group G1 and the second lens group G2 move along the optical axis.

  In the zoom lens according to the present embodiment, the first lens group G1 is moved to the object side along the optical axis as the focusing lens group, thereby focusing from an object at infinity to a near object.

Table 1 below lists values of specifications of the zoom lens according to the present example.
In Table 1, f indicates a focal length.
In [Surface Data], the surface number is the order of the optical surfaces counted from the object side, r is the radius of curvature, and d is the surface interval (the interval on the optical axis between the nth surface and the (n + 1) th surface (n is an integer). ), Nd represents the refractive index with respect to the d-line (wavelength 587.6 nm), and νd represents the Abbe number with respect to the d-line (wavelength 587.6 nm). Further, the object plane indicates the object plane, the variable indicates the variable plane spacing, the stop S indicates the aperture stop S, and the image plane indicates the image plane I. The radius of curvature r = ∞ indicates a plane. For the aspherical surface, * is added to the surface number, and the value of the paraxial radius of curvature is indicated in the column of the radius of curvature r.

[Aspherical data] shows an aspherical coefficient and a conic constant 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 ]
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ + A12 × y ¹²
Here, y is the height in the direction perpendicular to the optical axis, S (y) is the distance (sag amount) along the optical axis direction from the tangential plane of the apex of the aspheric surface at the height y to the aspheric surface, κ Is a conic constant, A4, A6, A8, A10, and A12 are aspherical coefficients, and r is a radius of curvature (paraxial radius of curvature) of the reference spherical surface. “E−n” (n is an integer) indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”. The secondary aspherical coefficient A2 is 0 and is not shown.

In [Various data], FNO is the F number, ω is the half angle of view (unit is “°”), Y is the image height, TL is the total length of the zoom lens (from the first surface at the time of focusing on the object at infinity to the image surface I (Distance on the optical axis). The air conversion Bf is the back focus (distance on the optical axis between the lens surface closest to the image side and the image plane I) with the dummy glass FL removed from the zoom lens according to the present embodiment, β is the shooting magnification, and d0 is the object magnification. The distance on the optical axis from the first surface to the first surface, dn, indicates the variable distance between the nth surface and the (n + 1) th surface. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.
[Lens Group Data] indicates the start surface and focal length of each lens group.
[Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression of the zoom lens according to the present embodiment.

Here, the focal length f, the radius of curvature r, and other length units listed in Table 1 are generally “mm”. 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 -4971.9688 2.0000 1.883000 40.66
2 26.3000 0.1000 1.560930 36.64
* 3 20.9102 8.3000 1.000000
4 41.7495 6.0000 1.846660 23.80
5 172.2935 Variable 1.000000

6 571.0318 2.0000 1.729160 54.61
7 -80.4994 0.8000 1.000000
8 21.7945 1.0000 1.772500 49.62
9 15.2210 4.5000 1.497820 82.57
10 49.1048 2.6000 1.000000
11 (Aperture S) ∞ 1.2000 1.000000
12 30.5361 11.9000 1.497820 82.57
13 -20.2027 1.0000 1.883000 40.66
14 41.2241 4.3500 1.000000
* 15 81.5098 3.8000 1.677900 54.89
16 -23.3482 16.5500 1.000000
17 -18.3979 3.5000 1.688930 31.16
18 -14.3586 1.5000 1.816000 46.59
19 -36.8838 Variable 1.000000

20 ∞ 2.0000 1.516800 64.12
21 ∞ Variable 1.000000

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
3 0.0274 6.78771E-07 1.25604E-09 -1.73623E-11 3.54718E-14 -0.32980E-16
15 0.3278 -1.52946E-06 6.46816E-09 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Various data]
Scaling ratio 2.69

W M T
f 28.8 50.0 77.6
FNO 3.6 4.6 5.9
ω 39.4 23.5 15.5
Y 21.6 21.6 21.6
TL 138.096 124.193 130.033
Air conversion Bf 17.948 33.285 53.253

(When focusing on an object at infinity)
W M T
f 28.80000 50.00000 77.60000
d0 ∞ ∞ ∞
d5 48.36733 19.12659 4.99821
d19 13.00000 28.33774 48.30574
d21 3.62901 3.62901 3.62901

(When focusing on a finite distance object)
W M T
β -0.03352 -0.03344 -0.03340
d0 811.7935 1447.7945 2275.7959
d5 51.54475 20.95678 6.17746
d19 13.00000 28.33774 48.30574
d21 3.63428 3.63427 3.63426

(When focusing on a short distance object)
W M T
β -0.14567 -0.25376 -0.39562
d0 151.1474 151.1474 151.1474
d5 61.86733 32.62659 18.49821
d19 13.00000 28.33774 48.30574
d21 3.72635 3.92342 4.34136

[Lens group data]
Group start surface f
1 1 -52.39559
2 6 37.90707

[Conditional expression values]
(1) (r2n1 + r1n1) / (r2n1-r1n1) = − 0.992
(2) (r2n3-r1n3) / (r2n3 + r1n3) = 0.149
(3) Bfw / D2 = 0.328
(4) D2r / Bfw = 0.922
(5) f2 / ft = 0.488
(6) (−f2r) /f2=1.184
(7) f2p / f2 = 0.717
(8) (r2r + r1r) / (r2r-r1r) = 2.990
(9) (r2p + r1p) / (r2p−r1p) = − 0.555

  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.

  In each aberration diagram, FNO represents an F number, and Y represents an image height. d indicates the aberration at the d-line (wavelength 587.6 nm), and g indicates the aberration at the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The coma aberration diagram shows coma aberration at each image height Y. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  From each aberration diagram, the zoom lens according to the present example has excellent optical performance by satisfactorily correcting various aberrations including spherical aberration, coma aberration, field curvature, and astigmatism from the wide-angle end state to the telephoto end state. You can see that it has.

(Second embodiment)
FIG. 3 is a diagram illustrating a lens configuration at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 2 of the present application, and a movement locus of each lens group at the time of zooming.
The zoom lens according to the present exemplary embodiment includes, in order from the object side along the optical axis, 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 along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, and a positive meniscus lens L12 having a convex surface facing the object side. The negative meniscus lens L11 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a negative meniscus lens L22 having a convex surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side. A cemented positive lens, an aperture stop S, a cemented negative lens of a biconvex positive lens L24 and a thick biconcave negative lens L25, a positive meniscus lens L26 having a concave surface facing the object side, and an image And a negative meniscus lens L27 having a convex surface on the side.

  A dummy glass FL corresponding to an optical low-pass filter is disposed between the second lens group G2 and the image plane I.

  Under the above configuration, in the zoom lens according to the present embodiment, the first lens group G1 and the second lens group G2 change so that the air gap between the first lens group G1 and the second lens group G2 changes during zooming from the wide-angle end state to the telephoto end state. The first lens group G1 and the second lens group G2 move along the optical axis.

In the zoom lens according to the present embodiment, the first lens group G1 is moved to the object side along the optical axis as the focusing lens group, thereby focusing from an object at infinity to a near object.
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 ∞

1 129.6401 1.8000 1.816000 46.59
* 2 21.0701 8.9601 1.000000
3 30.0752 5.0000 1.846660 23.80
4 45.1546 Variable 1.000000

5 863.7134 2.0000 1.719990 50.27
6 -61.3930 1.0000 1.000000
7 17.2972 1.0000 1.755000 52.34
8 12.7054 4.0000 1.487490 70.31
9 35.6021 2.6000 1.000000
10 (Aperture S) ∞ 1.2000 1.000000
11 50.7556 3.3000 1.497820 82.57
12 -22.5421 4.0448 1.834000 37.18
13 102.6004 7.7445 1.000000
14 -1687.0183 2.3000 1.755000 52.34
15 -27.0690 10.4203 1.000000
16 -16.4791 1.5000 1.603110 60.69
17 -35.1170 Variable 1.000000

18 ∞ 2.0000 1.516800 64.12
19 ∞ 1.0000 1.000000

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
2 -1.0221 2.31156E-05 -8.21484E-09 2.65178E-11 -2.36759E-14 0.30473E-16

[Various data]
Scaling ratio 2.69

W M T
f 28.8 50.0 77.6
FNO 3.6 4.6 5.9
ω 40.3 23.8 15.6
Y 21.6 21.6 21.6
TL 135.888 123.401 131.060
Air conversion Bf 30.026 46.751 68.524

(When focusing on an object at infinity)
W M T
f 28.80000 50.00000 77.60000
d0 ∞ ∞ ∞
d4 48.31067 19.09858 4.98405
d17 27.70760 44.43215 66.20563

(When focusing on a finite distance object)
W M T
β -0.03333 -0.03333 -0.03333
d0 814.8805 1450.8873 2278.8752
d4 51.22174 20.77536 6.06446
d17 27.70760 44.43215 66.20563

(When focusing on a short distance object)
W M T
β -0.11369 -0.18777 -0.30039
d0 204.1827 217.1539 209.2043
d4 58.23991 28.54415 14.72028
d17 27.70760 44.43215 66.20563

[Lens group data]
Group start surface f
1 1 -50.15165
2 5 39.56434

[Conditional expression values]
(1) (r2n1 + r1n1) / (r2n1-r1n1) =-1.388
(2) (r2n3-r1n3) / (r2n3 + r1n3) = 0.338
(3) Bfw / D2 = 0.730
(4) D2r / Bfw = 0.347
(5) f2 / ft = 0.510
(6) (−f2r) /f2=1.342
(7) f2p / f2 = 0.920
(8) (r2r + r1r) / (r2r-r1r) = 2.768
(9) (r2p + r1p) / (r2p−r1p) = − 1.033

  FIGS. 4 (a), 4 (b), and 4 (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.

  From each aberration diagram, the zoom lens according to the present example has excellent optical performance by satisfactorily correcting various aberrations including spherical aberration, coma aberration, field curvature, and astigmatism from the wide-angle end state to the telephoto end state. You can see that it has.

(Third embodiment)
FIG. 5 is a diagram illustrating a lens configuration at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to the third example of the present application, and a movement locus of each lens unit at the time of zooming.
The zoom lens according to the present exemplary embodiment includes, in order from the object side along the optical axis, 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 along the optical axis, a negative meniscus lens L11 having a convex surface facing the object side, and a positive meniscus lens L12 having a convex surface facing the object side. The negative meniscus lens L11 is a composite aspherical lens formed by forming a resin layer provided on the glass surface on the image side into an aspherical shape.

  The second lens group G2 includes, in order from the object side along the optical axis, a biconvex positive lens L21, a negative meniscus lens L22 having a convex surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side. A cemented positive lens, an aperture stop S, a cemented negative lens of a biconvex positive lens L24 and a biconcave negative lens L25, a positive meniscus lens L26 having a concave surface on the object side, and a convex surface on the image side. And a positive meniscus lens L27.

  A dummy glass FL corresponding to an optical low-pass filter is disposed between the second lens group G2 and the image plane I.

  Under the above configuration, in the zoom lens according to the present embodiment, the first lens group G1 and the second lens group G2 change so that the air gap between the first lens group G1 and the second lens group G2 changes during zooming from the wide-angle end state to the telephoto end state. The first lens group G1 and the second lens group G2 move along the optical axis.

In the zoom lens according to the present embodiment, the first lens group G1 is moved to the object side along the optical axis as the focusing lens group, thereby focusing from an object at infinity to a near object.
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 ∞

1 181.8323 2.0000 1.834810 42.73
2 23.7000 0.2000 1.560930 36.64
* 3 19.3695 8.1530 1.000000
4 31.3960 6.0000 1.846660 23.80
5 57.1323 Variable 1.000000

6 571.0318 2.0000 1.719990 50.27
7 -80.4994 0.8000 1.000000
8 16.9920 1.2000 1.729160 54.61
9 12.7238 4.0000 1.497820 82.57
10 35.5718 2.6000 1.000000
11 (Aperture S) ∞ 1.2000 1.000000
12 45.1569 3.3000 1.497820 82.57
13 -26.0091 1.0000 1.834000 37.18
14 159.9003 10.1363 1.000000
15 -1177.4977 2.5000 1.772500 49.62
16 -29.2117 6.6369 1.000000
17 -15.9456 1.0000 1.755000 52.34
18 -30.8472 Variable 1.000000

19 ∞ 2.0000 1.516800 64.12
20 ∞ 1.0000 1.000000

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10 A12
3 0.1622 5.01092E-06 8.24552E-10 7.54407E-12 -1.05031E-14 -0.65754E-17

[Various data]
Scaling ratio 2.69

W M T
f 28.8 50.0 77.6
FNO 3.6 4.6 5.9
ω 40.122 23.828 15.628
Y 21.6 21.6 21.6
TL 135.711 123.599 131.743
Air conversion Bf 33.218 50.317 72.574

(When focusing on an object at infinity)
W M T
f 28.80591 50.00000 77.60000
d0 ∞ ∞ ∞
d5 49.08640 19.87851 5.75917
d18 30.89900 47.99457 70.25727

(When focusing on a finite distance object)
W M T
β -0.03333 -0.03333 -0.03333
d0 816.2127 1452.0423 2280.0511
d5 51.93388 21.51899 6.81618
d18 30.89900 47.99457 70.25727

(When focusing on a short distance object)
W M T
β -0.11408 -0.18861 -0.30237
d0 204.5435 217.1181 208.6691
d5 58.83130 29.16116 15.34741
d18 30.89900 47.99457 70.25727

[Lens group data]
Group start surface f
1 1 -49.60599
2 6 40.01316

[Conditional expression values]
(1) (r2n1 + r1n1) / (r2n1-r1n1) =-1.238
(2) (r2n3-r1n3) / (r2n3 + r1n3) = 0.560
(3) Bfw / D2 = 0.913
(4) D2r / Bfw = 0.200
(5) f2 / ft = 0.516
(6) (−f2r) /f2=1.125
(7) f2p / f2 = 0.968
(8) (r2r + r1r) / (r2r−r1r) = 3.140
(9) (r2p + r1p) / (r2p−r1p) = − 1.051

  6 (a), 6 (b), and 6 (c) respectively show the infinite object combination 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. FIG. 5 is a diagram showing various aberrations during focusing.

  From each aberration diagram, the zoom lens according to the present example has excellent optical performance by satisfactorily correcting various aberrations including spherical aberration, coma aberration, field curvature, and astigmatism from the wide-angle end state to the telephoto end state. You can see that it has.

  According to each of the embodiments described above, it is possible to realize a high-performance zoom lens in which various aberrations such as spherical aberration, coma, and astigmatism are favorably corrected. In particular, the zoom lens according to each embodiment has a comprehensive angle of about 79 to 31 ° and a large aperture of about F3.5 to 5.6, and is small in size with a small number of lenses. Further, the zoom lens according to each embodiment is suitable not only for a camera taking lens described later but also for a printing lens and a copying lens.

In addition, each said Example has shown one specific example of this invention, and this invention is not limited to these. The following contents can be appropriately adopted within a range that does not impair the optical performance of the zoom lens of the present application.
The numerical example of the zoom lens of the present application is shown as having a two-group configuration, but the present application is not limited to this, and a zoom lens of another group configuration (for example, a third group or a fourth group) 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 side of the zoom lens of the present application may be used.

  The zoom lens according to each of the above embodiments performs focusing from an object at infinity to an object at a short distance by extending the first lens group. However, the present invention is not limited to this, and the zoom lens of the present application performs focusing by moving a part of one of the lens groups, the entire lens group, or a plurality of lens groups in the optical axis direction as a focusing lens group. It is good also as a structure. Specifically, a rear focus method in which the entire second lens group is a focusing lens group, a rear focus method in which a part of the second lens group is a focusing lens group, or an inner focus method may be employed. 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 in a direction perpendicular to the optical axis as an anti-vibration lens group, or an in-plane direction including the optical axis It is also possible to adopt a configuration in which image blur caused by camera shake or the like is corrected by rotating (swinging) to the right. 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 vibration-proof 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, it is preferable that the aperture stop is disposed in the second lens group or in the vicinity of the second lens group, and the role may be substituted by a lens frame without providing a member as the aperture stop. .
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.

Next, a camera equipped with the zoom lens of the present application will be described with reference to FIG.
FIG. 7 is a diagram illustrating a configuration of a camera including the zoom lens of the present application.
As shown in FIG. 7, the camera 1 is a so-called mirrorless camera with interchangeable lenses provided with the zoom lens according to the first embodiment as the photographing lens 2.
In the camera 1, light from an object (subject) (not shown) is collected by the photographing lens 2 and is on the imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) (not shown). A subject image is formed on the screen. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.
When the release button (not shown) is pressed by the photographer, the subject image generated by the imaging unit 3 is stored 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 a high-performance zoom lens in which various aberrations are corrected favorably. Therefore, this camera 1 can correct various aberrations well and realize high optical performance. It should be noted that the same effects as those of the camera 1 can be obtained even if a camera equipped with the zoom lenses according to the second and third embodiments as the photographing lens 2 is configured. Further, even when the zoom lens according to each of the above embodiments is mounted on a single-lens reflex camera having a quick return mirror and observing a subject with a finder optical system, 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 shown in FIG. 8 is a zoom lens manufacturing method including a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side. The following steps S1 to S4 are included.

Step S1: The first lens group is made up of one negative lens component and one positive lens component in order from the object side.
Step S2: The second lens group includes, in order from the object side, a positive lens component, a cemented positive lens composed of a negative lens and a positive lens, and a cemented negative lens composed of a positive lens and a negative lens.

Step S3: The first lens group satisfies the following conditional expression (1), and the first and second lens groups are sequentially arranged in the lens barrel from the object side.
(1) -2.00 <(r2n1 + r1n1) / (r2n1-r1n1) <0.00
However,
r1n1: radius of curvature of the most object side lens surface in the negative lens component in the first lens group r2n1: radius of curvature of the most image side lens surface in the negative lens component in the first lens group

  Step S4: By providing a known moving mechanism in the lens barrel, the distance between the first lens group and the second lens group is changed at the time of zooming from the wide-angle end state to the telephoto end state.

  According to the zoom lens manufacturing method of the present application, it is possible to manufacture a high-performance zoom lens in which various aberrations are favorably corrected.

G1 First lens group G2 Second lens group FL Dummy glass S Aperture stop I Image surface W Wide-angle end state T Telephoto end state

Claims (15)

In order from the object side, the first lens group having a negative refractive power and a second lens group having a positive refractive power,
The first lens group is composed of one negative lens component and one positive lens component in order from the object side,
The second lens group comprises, in order from the object side, a positive lens component, a cemented positive lens obtained by cementing a negative lens and a positive lens in order from the object side, the cemented negative formed by joining a positive lens and a negative lens in order from the object side A lens,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes,
A zoom lens satisfying the following conditional expression:
-2.00 <(r2n1 + r1n1) / (r2n1-r1n1) <0.00
However,
r1n1: radius of curvature of the most object side lens surface in the negative lens component in the first lens group r2n1: radius of curvature of the most image side lens surface in the negative lens component in the first lens group
The lens component means a cemented lens formed by joining two or more lenses or a single lens. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.00 <(r2n3-r1n3) / (r2n3 + r1n3) <1.00
However,
r1n3: radius of curvature of the lens surface closest to the object side in the cemented negative lens in the second lens group r2n3: radius of curvature of the lens surface closest to the image side in the cemented negative lens in the second lens group The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.10 <Bfw / D2 <1.50
However,
Bfw: Back focus of the zoom lens in the wide-angle end state D2: Total thickness of the second lens group   The second lens group further includes a meniscus negative lens component that is disposed closest to the image side and has a concave surface facing the object side, and a positive lens component that is disposed adjacent to the object side of the negative lens component. The zoom lens according to claim 1, further comprising: a zoom lens according to claim 1; The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
0.10 <D2r / Bfw <2.00
However,
D2r: Distance between the negative lens component in the second lens group and the positive lens component arranged adjacent to the object side Bfw: Back focus of the zoom lens in the wide-angle end state The zoom lens according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
0.20 <f2 / ft <0.65
However,
ft: focal length of the zoom lens in the telephoto end state f2: focal length of the second lens group The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
0.60 <(− f2r) / f2 <2.00
However,
f2r: focal length of the negative lens component in the second lens group f2: focal length of the second lens group The zoom lens according to claim 4, wherein the following conditional expression is satisfied.
0.50 <f2p / f2 <2.00
However,
f2p: focal length of the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group f2: focal length of the second lens group 9. The zoom lens according to claim 4, wherein the following conditional expression is satisfied: 9.
1.00 <(r2r + r1r) / (r2r−r1r) <8.00
However,
r1r: radius of curvature of the lens surface closest to the object in the negative lens component in the second lens group r2r: radius of curvature of the lens surface closest to the image in the negative lens component in the second lens group The zoom lens according to any one of claims 4, 5, and 7 to 9, wherein the following conditional expression is satisfied.
−3.00 <(r2p + r1p) / (r2p−r1p) <0.00
However,
r1p: radius of curvature of the lens surface closest to the object side in the positive lens component arranged adjacent to the object side of the negative lens component in the second lens group r2p: the negative lens component in the second lens group The radius of curvature of the lens surface closest to the image side in the positive lens component arranged adjacent to the object side   11. The zoom lens according to claim 1, further comprising an aperture stop closer to the image side than the positive lens component arranged closest to the object side in the second lens group.   The zoom lens according to claim 11, wherein the aperture stop is disposed adjacent to an image side of the cemented positive lens in the second lens group.   The zoom lens according to any one of claims 1 to 12, wherein the first lens group has at least one aspherical surface.   The zoom lens according to any one of claims 1 to 13, wherein the second lens group has at least one aspherical surface.   An optical apparatus comprising the zoom lens according to any one of claims 1 to 14.

Images