JP2015084037A - Variable power optical system, optical device, and method for manufacturing variable power optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable power optical system that is small in size, has a high variable power ratio, reduces ghosts or flares, and has high optical performance, and an optical device and a method for manufacturing the variable power optical system.SOLUTION: The variable power optical system includes, successively from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a positive fourth lens group G4, and a fifth lens group G5. An antireflection film is disposed on at least one of optical surfaces in the first lens group G1, the second lens group G2, and the fifth lens group G5; and the antireflection film includes at least one layer formed by using a wet process. Upon varying powers 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, a distance between the second lens group G2 and the third lens group G3, a distance between the third lens group G3 and the fourth lens group G4, and a distance between the fourth lens group G4 and the fifth lens group G5 are varied, while a position of the fifth lens group G5 is fixed. The variable power optical system satisfies predetermined conditional formulae.

Description

  The present invention relates to a variable magnification optical system, an optical apparatus, and a method for manufacturing the variable magnification optical system.

  Conventionally, as a variable power optical system suitable for an interchangeable lens for a camera, a digital camera, a video camera, and the like, many lenses having a positive refractive power in the most object side lens group have been proposed (for example, Patent Document 1). reference.). Further, in recent years, for such a variable magnification optical system, not only aberration performance but also ghost and flare, which are one of the factors that impair optical performance, are becoming more severe. Therefore, higher performance is also required for the antireflection film applied to the lens surface of the variable magnification optical system, and multilayer film design technology and film formation technology continue to advance to meet such requirements (for example, patents) See reference 2.)

JP 2007-292994 A JP 2000-356704 A

  However, the conventional variable power optical system as described above has a problem that it is difficult to obtain sufficiently high optical performance if it is attempted to reduce the size while maintaining a high zoom ratio. At the same time, the lens surface in the conventional variable magnification optical system also has a problem that reflected light that becomes ghost or flare is easily generated.

  Therefore, the present invention has been made in view of the above-described problems, and has a variable power ratio, a small size, a reduced ghost and flare, and a high optical performance, an optical apparatus, and a variable power ratio. It is an object of the present invention to provide a method for manufacturing an optical system.

In order to solve the above problems, the present invention
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A group and a fifth lens group,
An antireflection film is provided on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group, and the antireflection film is a layer formed using a wet process. At least one layer,
At the time of zooming from the wide angle end state to the telephoto end state, the distance between the first lens group and the second lens group, the distance between the second lens group and the third lens group, the third lens group and the The distance between the fourth lens group and the distance between the fourth lens group and the fifth lens group are changed, and the position of the fifth lens group is fixed;
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.650 <(− f2) / fw <1.180
0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

The present invention also provides
Provided is an optical device comprising the variable magnification optical system.

The present invention also provides
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A variable magnification optical system having a group and a fifth lens group,
An antireflection film is provided on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group, and the antireflection film has at least one layer formed by a wet process. To include layers,
The first lens group and the second lens group satisfy the following conditional expression:
At the time of zooming from the wide angle end state to the telephoto end state, the distance between the first lens group and the second lens group, the distance between the second lens group and the third lens group, the third lens group and the A variable power optical system characterized in that the distance between the fourth lens group and the distance between the fourth lens group and the fifth lens group are changed so that the position of the fifth lens group is fixed. A manufacturing method is provided.
0.650 <(− f2) / fw <1.180
0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

  According to the present invention, it is possible to provide a variable magnification optical system, an optical device, and a method for manufacturing the variable magnification optical system that have a high zoom ratio, reduce ghosts and flares, are small, and have high optical performance. it can.

(A), (b), (c), (d), and (e) are the wide-angle end state, the first intermediate focal length state, and the second intermediate state of the variable magnification optical system according to the first example of the present application, respectively. It is sectional drawing in a focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state. (A), (b), and (c) are objects at infinity in the wide-angle end state, the first intermediate focal length state, and the second intermediate focal length state of the variable magnification optical system according to the first example of the present application, respectively. It is an aberration diagram at the time of focusing. FIGS. 7A and 7B are graphs showing various aberrations when the object at infinity is in focus in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the first example of the present application, respectively. (A), (b), (c), (d), and (e) are the wide-angle end state, the first intermediate focal length state, and the second intermediate state of the variable magnification optical system according to the second example of the present application, respectively. It is sectional drawing in a focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state. (A), (b), and (c) are objects at infinity in the wide-angle end state, the first intermediate focal length state, and the second intermediate focal length state of the variable magnification optical system according to the second example of the present application, respectively. It is an aberration diagram at the time of focusing. FIGS. 9A and 9B are graphs showing various aberrations when the object at infinity is in focus in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the second example of the present application, respectively. (A), (b), (c), (d), and (e) are the wide-angle end state, the first intermediate focal length state, and the second intermediate state of the variable magnification optical system according to the third example of the present application, respectively. It is sectional drawing in a focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state. (A), (b), and (c) are objects at infinity in the wide-angle end state, the first intermediate focal length state, and the second intermediate focal length state of the variable magnification optical system according to the third example of the present application, respectively. It is an aberration diagram at the time of focusing. FIGS. 7A and 7B are graphs showing various aberrations when the object at infinity is in focus in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the third example of the present application, respectively. FIGS. (A), (b), (c), (d), and (e) are respectively the wide-angle end state, the first intermediate focal length state, and the second intermediate state of the variable magnification optical system according to the fourth example of the present application. It is sectional drawing in a focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state. (A), (b), and (c) are objects at infinity in the wide-angle end state, the first intermediate focal length state, and the second intermediate focal length state of the variable magnification optical system according to the fourth example of the present application, respectively. It is an aberration diagram at the time of focusing. FIGS. 9A and 9B are graphs showing various aberrations when the object at infinity is in focus in the third intermediate focal length state and the telephoto end state of the zoom optical system according to the fourth example of the present application, respectively. It is a figure which shows the structure of the camera provided with the variable magnification optical system of this application. It is a figure which shows the outline of the manufacturing method of the variable magnification optical system of this application. The figure which shows an example of a mode that the light ray which injected into the variable magnification optical system which concerns on 1st Example of this application reflects in the 1st reflective surface and the 2nd reflective surface, and forms a ghost and a flare in an image surface. is there. It is explanatory drawing which shows an example of the layer structure of an antireflection film. It is a graph which shows the spectral characteristic of an antireflection film. It is a graph which shows the spectral characteristics of the antireflection film concerning a modification. It is a graph which shows the incident angle dependence of the spectral characteristic of the antireflection film concerning a modification. It is a graph which shows the spectral characteristic of the anti-reflective film produced with the prior art. It is a graph which shows the incident angle dependence of the spectral characteristic of the anti-reflective film produced with the prior art.

Hereinafter, a variable magnification optical system, an optical apparatus, and a method for manufacturing the variable magnification optical system of the present application will be described.
The variable magnification optical system of the present application includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, An antireflection film on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group. And the antireflection film includes at least one layer formed by using a wet process, and the first lens group and the second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The distance between the lens group, the distance between the second lens group and the third lens group, the distance between the third lens group and the fourth lens group, and the distance between the fourth lens group and the fifth lens group. It is characterized in that the interval changes. With this configuration, the variable magnification optical system of the present application realizes variable magnification from the wide-angle end state to the telephoto end state, and can suppress each variation of distortion aberration, astigmatism, and spherical aberration associated with variable magnification. .

  The variable magnification optical system of the present application is characterized in that the position of the fifth lens group is fixed at the time of zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to change the height from the optical axis of the peripheral rays incident from the fourth lens group to the fifth lens group at the time of zooming. Thereby, astigmatism fluctuation at the time of zooming can be suppressed more favorably.

The variable magnification optical system of the present application is characterized by satisfying the following conditional expressions (1) and (2).
(1) 0.650 <(− f2) / fw <1.180
(2) 0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

Conditional expression (1) defines an appropriate focal length range of the second lens group. By satisfying conditional expression (1), the variable magnification optical system of the present application can suppress variations in spherical aberration and astigmatism during magnification.
If the corresponding value of conditional expression (1) of the variable magnification optical system of the present application is below the lower limit value, it becomes difficult to suppress the variation of spherical aberration and astigmatism that occur in the second lens group at the time of zooming, It becomes impossible to realize high optical performance. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (1) to 0.760.
On the other hand, when the corresponding value of the conditional expression (1) of the zoom optical system of the present application exceeds the upper limit value, in order to obtain a predetermined zoom ratio, the distance between the first lens group and the second lens group at the time of zooming It is necessary to increase the amount of change. This not only makes it difficult to reduce the size, but also greatly changes the height from the optical axis of the off-axis light beam incident on the second lens group from the first lens group with zooming. For this reason, the fluctuation of astigmatism becomes excessive at the time of zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 1.120.

Conditional expression (2) defines an appropriate focal length range of the first lens group. By satisfying conditional expression (2), the variable magnification optical system of the present application can suppress variations in spherical aberration and astigmatism during magnification.
If the corresponding value of conditional expression (2) of the variable magnification optical system of the present application is less than the lower limit value, it becomes difficult to suppress variations in spherical aberration and astigmatism that occur in the first lens group during magnification, It becomes impossible to realize high optical performance. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.421.
On the other hand, when the corresponding value of conditional expression (2) of the variable magnification optical system of the present application exceeds the upper limit value, the distance between the first lens group and the second lens group at the time of zooming is obtained in order to obtain a predetermined zoom ratio. It is necessary to increase the amount of change. This not only makes it difficult to reduce the size, but also the ratio between the diameter of the axial light beam incident on the first lens group and the diameter of the axial light beam incident on the second lens group changes greatly with zooming. For this reason, the variation of the spherical aberration becomes excessive at the time of zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 0.530.
With the above configuration, a variable magnification optical system having a high zoom ratio, a small size, and high optical performance can be realized.

  In the variable magnification optical system of the present application, an antireflection film is provided on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group. Includes at least one layer formed using a wet process. With this configuration, the variable magnification optical system of the present application can further reduce ghosts and flares caused by reflection of light from an object on an optical surface, and can achieve high imaging performance.

  In the variable magnification optical system of the present application, the antireflection film is a multilayer film, and the layer formed by using the wet process is a layer on the most surface side among the layers constituting the multilayer film. Is desirable. With this configuration, the refractive index difference between the layer formed using the wet process and air can be reduced, so that the reflection of light can be further reduced and ghosts and flares can be further reduced. Can do.

  Further, in the variable magnification optical system of the present application, when the refractive index with respect to the d-line (wavelength λ = 587.6 nm) of the layer formed using the wet process is nd, nd may be 1.30 or less. desirable. With this configuration, the refractive index difference between the layer formed using the wet process and air can be reduced, so that the reflection of light can be further reduced and ghosts and flares can be further reduced. Can do.

  The variable magnification optical system of the present application preferably has an aperture stop, and the optical surface provided with the antireflection film is preferably a concave lens surface when viewed from the aperture stop. Of the optical surfaces in the first lens group, the second lens group, and the fifth lens group, reflected light tends to be generated on a concave lens surface as viewed from the aperture stop. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable power optical system of the present application, it is desirable that the concave lens surface viewed from the aperture stop is an image surface side lens surface of the lens in the first lens group. Of the optical surfaces in the first lens group, reflected light tends to be generated on a concave lens surface as viewed from the aperture stop. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the zoom optical system of the present application, it is desirable that the concave lens surface as viewed from the aperture stop is an object side lens surface of the lens in the first lens group. Of the optical surfaces in the first lens group, reflected light tends to be generated on a concave lens surface as viewed from the aperture stop. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable magnification optical system of the present application, it is desirable that the concave lens surface viewed from the aperture stop is an image surface side lens surface of the first lens from the object side in the second lens group. Of the optical surfaces in the second lens group, reflected light tends to be generated on concave lens surfaces as viewed from the aperture stop. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable magnification optical system of the present application, it is desirable that the concave lens surface when viewed from the aperture stop is the object side lens surface of the lens in the fifth lens group. Of the optical surfaces in the fifth lens group, reflected light tends to be generated on a concave lens surface as viewed from the aperture stop. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable magnification optical system of the present application, it is desirable that the optical surface provided with the antireflection film is a concave lens surface when viewed from the object side. Of the optical surfaces in the first lens group, the second lens group, and the fifth lens group, reflected light tends to be generated on a concave lens surface as viewed from the object side. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable power optical system of the present application, it is desirable that the concave lens surface when viewed from the object side is an image surface side lens surface of a lens in the first lens group. Of the optical surfaces in the first lens group, reflected light tends to be generated on a concave lens surface as viewed from the object side. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  In the variable magnification optical system of the present application, it is desirable that the concave lens surface when viewed from the object side is the object side lens surface of the second lens from the object side in the second lens group. Of the optical surfaces in the second lens group, reflected light tends to be generated on a concave lens surface as viewed from the object side. For this reason, a ghost and flare can be effectively reduced by forming an antireflection film on such a lens surface.

  The antireflection film in the variable magnification optical system of the present application is not limited to a wet process, and may be formed by a dry process or the like. In this case, the antireflection film preferably includes at least one layer having a refractive index of 1.30 or less. With this configuration, even when the antireflection film is formed by a dry process or the like, the same effect as when the antireflection film is formed by a wet process can be obtained. Note that the layer having a refractive index of 1.30 or less is preferably the outermost layer among the layers constituting the multilayer film.

Further, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (3).
(3) 5.300 <f1 / (− f2) <8.500
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group

Conditional expression (3) defines an appropriate range of the focal length ratio between the first lens group and the second lens group. By satisfying conditional expression (3), the variable magnification optical system of the present application can suppress variations in spherical aberration and astigmatism during magnification.
When the corresponding value of the conditional expression (3) of the variable magnification optical system of the present application is below the lower limit value, the negative spherical aberration generated in the first lens group at the telephoto end state becomes too large, and the variation of the spherical aberration at the time of zooming If it becomes excessive, high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 5.800. Furthermore, in order to ensure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 6.250. Furthermore, in order to ensure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 6.750.
On the other hand, if the corresponding value of conditional expression (3) of the variable magnification optical system of the present application exceeds the upper limit value, it is difficult to suppress the variation of spherical aberration and astigmatism generated in the second lens group at the time of zooming. Therefore, high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 8.050. Furthermore, in order to ensure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (3) to 7.700. Furthermore, in order to ensure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 7.320.

  In the zoom optical system of the present application, it is preferable that the third lens group moves toward the object side when zooming from the wide-angle end state to the telephoto end state. With this configuration, the refractive power of the fourth lens group can be reduced as compared with the case where the third lens group does not move toward the object side. As a result, it is possible to suppress fluctuations in astigmatism that occur in the fourth lens group during zooming.

  In the zoom optical system according to the present application, it is preferable that the first lens unit moves toward the object side when zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to suppress a change in height from the optical axis of the off-axis light beam that passes through the first lens group during zooming. Thereby, not only can the diameter of the first lens group be reduced, but also fluctuations in astigmatism can be suppressed during zooming.

  In the variable magnification optical system of the present application, it is desirable that the fifth lens group has a positive refractive power. With this configuration, the use magnification of the fifth lens group becomes smaller than the same magnification, and as a result, the combined focal length from the first lens group to the fourth lens group can be relatively increased. As a result, the influence of decentration coma aberration and the like caused by the decentration of the lenses occurring in the first lens group to the fourth lens group during manufacturing can be relatively reduced, and high optical performance can be realized. it can.

  In the zoom optical system of the present application, it is desirable that the distance between the first lens group and the second lens group is increased when zooming from the wide-angle end state to the telephoto end state. With this configuration, it is possible to increase the magnification of the second lens group, and it is possible to suppress fluctuations in spherical aberration and astigmatism during zooming while efficiently realizing a high zoom ratio.

  In the zoom optical system of the present application, it is preferable that the distance between the second lens group and the third lens group is reduced when zooming from the wide-angle end state to the telephoto end state. With this configuration, the combined magnification of the third lens group and the fourth lens group can be increased, and the variation of spherical aberration and astigmatism are suppressed during zooming while efficiently realizing a high zoom ratio. be able to.

  In the zoom optical system of the present application, it is desirable that the distance between the fourth lens group and the fifth lens group is increased when zooming from the wide-angle end state to the telephoto end state. With this configuration, the combined magnification of the third lens group and the fourth lens group can be increased, and the variation of spherical aberration and astigmatism are suppressed during zooming while efficiently realizing a high zoom ratio. be able to.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (4).
(4) 0.040 <(− f2) / ft <0.092
However,
ft: focal length of the variable magnification optical system in the telephoto end state f2: focal length of the second lens group

Conditional expression (4) defines an appropriate focal length range of the second lens group. By satisfying conditional expression (4), the variable magnification optical system of the present application can suppress variations in spherical aberration and astigmatism during magnification.
If the corresponding value of conditional expression (4) of the variable magnification optical system of the present application is below the lower limit value, it becomes difficult to suppress variations in spherical aberration and astigmatism that occur in the second lens group during magnification. It becomes impossible to realize high optical performance. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 0.050.
On the other hand, when the corresponding value of the conditional expression (4) of the zoom optical system of the present application exceeds the upper limit value, in order to obtain a predetermined zoom ratio, the distance between the first lens group and the second lens group at the time of zooming It is necessary to increase the amount of change. This not only makes it difficult to reduce the size, but also changes the diameter of the on-axis light beam incident from the first lens group to the second lens group with a change in magnification. For this reason, the variation of the spherical aberration becomes excessive at the time of zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (4) to 0.084.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (5).
(5) 5.000 <f1 / fw <7.800
However,
fw: focal length of the variable magnification optical system in the wide-angle end state f1: focal length of the first lens group

Conditional expression (5) defines an appropriate focal length range of the first lens group. By satisfying conditional expression (5), the variable magnification optical system of the present application can suppress variations in spherical aberration and astigmatism during magnification.
If the corresponding value of conditional expression (5) of the variable magnification optical system of the present application is lower than the lower limit value, it becomes difficult to suppress fluctuations in spherical aberration and astigmatism that occur in the first lens group at the time of zooming, It becomes impossible to realize high optical performance. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to 5.800.
On the other hand, when the corresponding value of the conditional expression (5) of the zoom optical system of the present application exceeds the upper limit value, in order to obtain a predetermined zoom ratio, the distance between the first lens group and the second lens group at the time of zooming It is necessary to increase the amount of change. This not only makes it difficult to reduce the size, but also causes the height of the off-axis light beam passing through the first lens group from the optical axis to change greatly with zooming. For this reason, the fluctuation of astigmatism becomes excessive at the time of zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (5) to 7.550.

  The optical device of the present application is characterized by having the variable magnification optical system having the above-described configuration. Thereby, an optical device having a high zoom ratio, a small size, and high optical performance can be realized.

The variable magnification optical system manufacturing method of the present application includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. And a variable magnification optical system having a fourth lens group having a positive refractive power and a fifth lens group, in the first lens group, the second lens group, and the fifth lens group. An antireflection film is provided on at least one of the optical surfaces, and the antireflection film includes at least one layer formed using a wet process, and the first lens group and the second lens group are described below. And satisfying the conditional expressions (1) and (2), and at the time of zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group, and the second lens group The distance from the third lens group, the third lens group and the fourth lens Distance between the distance, and the fifth lens group and the fourth lens group is changed, the position of the fifth lens group is characterized in that so as to be fixed. Thereby, a variable power optical system having a high zoom ratio, a small size, and high optical performance can be manufactured.
(1) 0.650 <(− f2) / fw <1.180
(2) 0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

Hereinafter, a variable magnification optical system according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
1 (a), FIG. 1 (b), FIG. 1 (c), FIG. 1 (d), and FIG. 1 (e) are respectively the wide-angle end state of the variable magnification optical system according to the first example of the present application, It is sectional drawing in a 1st intermediate | middle focal distance state, a 2nd intermediate | middle focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. Become.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a negative surface having a concave surface directed toward the object side. It consists of a cemented lens with a meniscus lens L24. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 is composed of a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32 in order from the object side. An aperture stop S is provided on the object side of the third lens group G3.
The fourth lens group G4 includes, in order from the object side, a cemented lens of a biconvex positive lens L41 and a biconcave negative lens L42, and a negative meniscus with a biconvex positive lens L43 and a concave meniscus facing the object side. A cemented lens with a lens L44, a cemented lens with a biconcave negative lens L45 and a biconvex positive lens L46, a biconvex positive lens L47, and a negative meniscus lens L48 with a concave surface facing the object side. It consists of a cemented lens. The negative meniscus lens L48 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The fifth lens group G5 includes, in order from the object side, a cemented lens including a positive meniscus lens L51 having a concave surface facing the object side and a negative meniscus lens L52 having a concave surface facing the object side. The negative meniscus lens L52 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The variable magnification optical system according to the present example includes the image side lens surface (surface number 7) of the negative meniscus lens L21 of the second lens group G2 and the object side of the biconcave negative lens L22 of the second lens group G2. An antireflection film described later is formed on the lens surface (surface number 8).

With the above-described configuration, in the zoom optical system according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 and the second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The air gap between G2 and the third lens group G3, the air gap between the third lens group G3 and the fourth lens group G4, and the air gap between the fourth lens group G4 and the fifth lens group G5 are changed. The first lens group G1 to the fourth lens group G4 move along the optical axis.
Specifically, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side during zooming. The second lens group G2 moves toward the object side from the wide-angle end state to the third intermediate focal length state, and moves toward the image side from the third intermediate focal length state to the telephoto end state. The position of the fifth lens group G5 in the optical axis direction is fixed during zooming. The aperture stop S moves to the object side integrally with the fourth lens group G4 during zooming.

  Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the fourth lens group G4. And the fifth lens group G5 increase in air space. The air gap between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state to the first intermediate focal length state, decreases from the first intermediate focal length state to the second intermediate focal length state, and second It increases from the intermediate focal length state to the telephoto end state. During zooming, the air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the first intermediate focal length state and increases from the first intermediate focal length state to the second intermediate focal length state. , And decreases from the second intermediate focal length state to the telephoto end state.

Table 1 below lists values of specifications of the variable magnification optical system according to the present example.
In Table 1, f indicates the focal length, and BF indicates the back focus (the distance on the optical axis between the lens surface closest to the image side and the image plane I).
In [Surface data], the surface number is the order of the optical surfaces counted from the object side, r is the radius of curvature, d is the surface interval (the interval between the nth surface (n is an integer) and the n + 1th surface), and nd is The refractive index for d-line (wavelength 587.6 nm) and νd indicate the Abbe number for d-line (wavelength 587.6 nm), respectively. In addition, 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. The description of the refractive index of air nd = 1.00000 is omitted.

[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.
x = (h ² / r) / [1+ {1−κ (h / r) ² } ^1/2 ]
+ A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰ + A12h ¹²
Here, h is the height in the direction perpendicular to the optical axis, x is the distance (sag amount) from the tangent plane of the apex of the aspheric surface to the aspheric surface at the height h, and κ is the conic constant. , A4, A6, A8, A10, A12 are aspherical coefficients, and r is the radius of curvature of the reference sphere (paraxial radius of curvature). “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 variable magnification optical system (image from the first surface when focusing on an object at infinity) (Distance on the optical axis to the surface I), dn represents the variable distance between the nth surface and the (n + 1) th surface, and φ represents the diameter of the aperture stop S. W represents the wide-angle end state, M1 represents the first intermediate focal length state, M2 represents the second intermediate focal length state, M3 represents the third 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] shows the corresponding value of each conditional expression of the variable magnification optical system according to the present example.

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 ∞

1 165.4019 1.6350 1.902650 35.73
2 41.8893 9.2560 1.497820 82.57
3 -178.4364 0.1000
4 42.8430 5.1140 1.729160 54.61
5 515.0653 Variable

* 6 500.0000 1.0000 1.851350 40.10
7 9.0059 4.2479
8 -16.6413 1.0000 1.883000 40.66
9 50.8442 0.7538
10 32.1419 3.0566 1.808090 22.74
11 -18.1056 1.0000 1.883000 40.66
12 -29.3627 Variable

13 (Aperture S) ∞ Variable

14 27.1583 1.0000 1.883000 40.66
15 14.3033 3.4259 1.593190 67.90
16 -43.0421 Variable

17 12.5000 8.2427 1.670030 47.14
18 -79.2339 1.0000 1.883000 40.66
19 11.4345 2.0000
20 18.9834 3.3397 1.518600 69.89
21 -12.4126 1.0000 1.850260 32.35
22 -22.7118 1.5000
23 -46.2616 1.0000 1.902650 35.73
24 11.4391 3.5033 1.581440 40.98
25 -30.7870 0.1000
26 28.7953 5.0986 1.581440 40.98
27 -8.8012 1.0000 1.820800 42.71
* 28 -35.2149 Variable

29 -40.0000 1.6432 1.497820 82.57
30 -19.4318 1.0000 1.834410 37.28
* 31 -22.7996 BF

Image plane ∞

[Aspherical data]
6th surface κ 11.00000
A4 3.95289E-05
A6 -2.04622E-07
A8 -4.81392E-09
A10 9.83575E-11
A12 -5.88880E-13

No. 28 κ 1.0000
A4 -5.59168E-05
A6 -2.20298E-07
A8 3.87818E-10
A10 1.16318E-11
A12 0.00000

31st surface κ 1.00000
A4 2.65930E-05
A6 7.69228E-08
A8 -1.34346E-09
A10 0.00000
A12 0.00000

[Various data]
Scaling ratio 14.14

W T
f 9.47 to 133.87
FNO 4.12 to 5.78
ω 41.95 〜 3.27 °
Y 8.00-8.00
TL 112.25-165.65

W M1 M2 M3 T
f 9.47002 17.83631 60.50026 90.50043 133.87072
ω 41.95497 23.18274 7.18201 4.82759 3.26779
FNO 4.12 5.24 5.77 5.77 5.78
φ 8.52 8.52 9.55 10.30 11.04
d5 2.10000 12.15693 36.10717 41.77210 46.27797
d12 24.77744 16.39929 5.66327 3.74451 2.20000
d13 5.18928 3.23115 4.53928 3.63928 1.80000
d16 2.25000 4.20813 2.90000 3.80000 5.63928
d28 1.86861 12.02032 28.59900 32.29005 33.66620
BF 14.04947 14.04956 14.04989 14.04993 14.05005

[Lens group data]
Group start surface f
1 1 68.08250
2 6 -9.98760
3 14 38.80284
4 17 60.78065
5 29 129.99998

[Conditional expression values]
(1) (-f2) / fw = 1.055
(2) f1 / ft = 0.509
(3) f1 / (− f2) = 6.817
(4) (−f2) /ft=0.075
(5) f1 / fw = 7.189

FIGS. 2A, 2B, and 2C are respectively a wide-angle end state, a first intermediate focal length state, and a second intermediate focus of the zoom optical system according to the first example of the present application. It is an aberration diagram at the time of focusing on an object at infinity in the distance state.
FIGS. 3A and 3B are graphs showing various aberrations when the object at infinity is in focus in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the first example of the present application, respectively. It is.

  In each aberration diagram, FNO denotes an F number, and A denotes a light incident angle, that is, a half angle of view (unit: “°”). d indicates the aberration at the d-line (wavelength 587.6 nm), g indicates the aberration at the g-line (wavelength 435.8 nm), and those without d and g indicate the aberration at the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

Here, the cause of the occurrence of ghost and flare in the variable magnification optical system according to the present embodiment will be described.
FIG. 15 shows an example of how a light beam incident on the variable magnification optical system according to the present embodiment is reflected by the first reflecting surface and the second reflecting surface to form a ghost or flare on the image plane I. FIG.
In FIG. 15, when a light beam BM from the object side is incident on the variable magnification optical system as shown, a part of the light beam BM is an object side lens surface (surface number) of the biconcave negative lens L22 in the second lens group G2. 8. Reflected by the first reflecting surface on which reflected light that becomes ghost or flare is generated, and is further reflected on the image side lens surface (surface number 7, ghost or flare) of the negative meniscus lens L21 in the second lens group G2. The second reflection surface where the light is generated is reflected again, and finally reaches the image plane I to cause ghost and flare. The first reflecting surface is a concave lens surface viewed from the object side, and the second reflecting surface is a concave lens surface viewed from the aperture stop S.
Therefore, the variable magnification optical system according to the present embodiment suppresses the generation of reflected light and forms ghosts and flares by forming an antireflection film corresponding to light beams having a wide incident angle in a wide wavelength range on such a lens surface. Can be reduced.

(Second embodiment)
4 (a), FIG. 4 (b), FIG. 4 (c), FIG. 4 (d), and FIG. 4 (e) are respectively the wide-angle end state of the variable magnification optical system according to the second example of the present application, It is sectional drawing in a 1st intermediate | middle focal distance state, a 2nd intermediate | middle focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. Become.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. The cemented lens. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 is composed of a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32 in order from the object side. An aperture stop S is provided on the object side of the third lens group G3.
In order from the object side, the fourth lens group G4 includes a cemented lens of a positive meniscus lens L41 having a convex surface directed toward the object side and a negative meniscus lens L42 having a convex surface directed toward the object side, a biconvex positive lens L43, and an object. A cemented lens with a negative meniscus lens L44 having a concave surface facing side, a cemented lens with a biconcave negative lens L45 and a biconvex positive lens L46, and a biconvex positive lens L47 and a concave surface on the object side. And a cemented lens with a negative meniscus lens L48 directed. The negative meniscus lens L48 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The fifth lens group G5 includes, in order from the object side, a cemented lens including a positive meniscus lens L51 having a concave surface facing the object side and a negative meniscus lens L52 having a concave surface facing the object side. The negative meniscus lens L52 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The variable magnification optical system according to this example includes an object side lens surface (surface number 4) of the positive meniscus lens L13 of the first lens group G1 and an image surface side lens surface of the positive meniscus lens L13 of the first lens group G1 ( An antireflection film described later is formed on the surface number 5).

With the above-described configuration, in the zoom optical system according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 and the second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The air gap between G2 and the third lens group G3, the air gap between the third lens group G3 and the fourth lens group G4, and the air gap between the fourth lens group G4 and the fifth lens group G5 are changed. The first lens group G1 to the fourth lens group G4 move along the optical axis.
Specifically, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side during zooming. The second lens group G2 moves toward the object side from the wide-angle end state to the third intermediate focal length state, and moves toward the image side from the third intermediate focal length state to the telephoto end state. The position of the fifth lens group G5 in the optical axis direction is fixed during zooming. The aperture stop S moves to the object side integrally with the fourth lens group G4 during zooming.

Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the fourth lens group G4. And the fifth lens group G5 increase in air space. The air gap between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state to the first intermediate focal length state, decreases from the first intermediate focal length state to the second intermediate focal length state, and second It increases from the intermediate focal length state to the telephoto end state. During zooming, the air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the first intermediate focal length state and increases from the first intermediate focal length state to the second intermediate focal length state. , And decreases from the second intermediate focal length state to the telephoto end state.
Table 2 below provides values of specifications of the variable magnification optical system according to the present example.

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞

1 149.1393 1.6350 1.902650 35.73
2 39.3210 9.1912 1.497820 82.57
3 -200.0000 0.1000
4 41.9637 5.4484 1.729160 54.61
5 1039.4250 Variable

* 6 500.0000 1.0000 1.851350 40.10
7 9.7424 3.8435
8 -27.3991 1.0000 1.883000 40.66
9 89.0051 0.2895
10 21.6984 3.7554 1.808090 22.74
11 -15.0205 1.0000 1.883000 40.66
12 103.6128 Variable

13 (Aperture S) ∞ Variable

14 26.3876 1.0000 1.883000 40.66
15 13.2001 3.5030 1.593190 67.90
16 -39.4805 Variable

17 12.5000 8.2088 1.743200 49.26
18 25.6321 1.0000 1.834000 37.18
19 9.6066 2.0000
20 17.4828 3.0696 1.516800 63.88
21 -13.7429 1.0000 1.850260 32.35
22 -25.6259 1.5000
23 -19.7745 1.0000 1.850260 32.35
24 12.4270 3.9453 1.620040 36.40
25 -17.2177 0.3559
26 44.5160 5.3272 1.581440 40.98
27 -8.1562 1.0000 1.820800 42.71
* 28 -28.1926 Variable

29 -40.0000 1.7646 1.497820 82.57
30 -18.8409 1.0000 1.834410 37.28
* 31 -25.0038 BF

Image plane ∞

[Aspherical data]
6th surface κ 10.29120
A4 1.05982E-05
A6 1.47868E-07
A8 -6.64708E-09
A10 8.77431E-11
A12 -4.23990E-13

No. 28 κ 1.0000
A4 -7.26393E-05
A6 -3.38257E-07
A8 1.26743E-09
A10 -2.83030E-11
A12 0.00000

31st surface κ 1.00000
A4 2.68564E-05
A6 7.91224E-08
A8 -8.06538E-10
A10 0.00000
A12 0.00000

[Various data]
Scaling ratio 14.13

W T
f 10.30 to 145.50
FNO 4.08 to 5.71
ω 39.62 to 3.01 °
Y 8.00-8.00
TL 112.60-162.60

W M1 M2 M3 T
f 10.30001 18.00395 60.55030 89.50052 145.50102
ω 39.61866 23.08393 7.20247 4.88583 3.00545
FNO 4.08 4.79 5.49 5.75 5.72
φ 9.01 9.02 9.02 9.26 10.08
d5 2.10000 11.86757 33.84673 38.94667 43.98780
d12 24.38938 17.21960 5.86923 4.42463 2.20000
d13 2.46923 1.80000 4.59702 3.69702 1.80000
d16 5.02779 5.69702 2.90000 3.80000 5.69702
d28 1.62642 10.35671 26.30176 30.05048 31.92800
BF 14.04946 14.04953 14.04979 14.04990 14.05006

[Lens group data]
Group start surface f
1 1 64.91265
2 6 -9.00339
3 14 38.07719
4 17 46.69911
5 29 260.10501

[Conditional expression values]
(1) (−f2) /fw=0.874
(2) f1 / ft = 0.446
(3) f1 / (− f2) = 7.210
(4) (−f2) /ft=0.062
(5) f1 / fw = 6.302

FIGS. 5A, 5B, and 5C are respectively a wide-angle end state, a first intermediate focal length state, and a second intermediate focus of the variable magnification optical system according to the second example of the present application. It is an aberration diagram at the time of focusing on an object at infinity in the distance state.
FIGS. 6A and 6B are graphs showing various aberrations when focusing on an object at infinity in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the second example of the present application, respectively. It is.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Third embodiment)
7 (a), FIG. 7 (b), FIG. 7 (c), FIG. 7 (d), and FIG. 7 (e) are respectively the wide-angle end state of the variable magnification optical system according to the third example of the present application, It is sectional drawing in a 1st intermediate | middle focal distance state, a 2nd intermediate | middle focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. Become.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a negative surface having a concave surface directed toward the object side. It consists of a cemented lens with a meniscus lens L24. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 is composed of a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32 in order from the object side. An aperture stop S is provided on the object side of the third lens group G3.
The fourth lens group G4 includes, in order from the object side, a cemented lens of a biconvex positive lens L41 and a biconcave negative lens L42, and a negative meniscus with a biconvex positive lens L43 and a concave meniscus facing the object side. A cemented lens with a lens L44, a cemented lens with a biconcave negative lens L45 and a biconvex positive lens L46, a biconvex positive lens L47, and a negative meniscus lens L48 with a concave surface facing the object side. It consists of a cemented lens. The negative meniscus lens L48 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The fifth lens group G5 includes, in order from the object side, a cemented lens including a positive meniscus lens L51 having a concave surface facing the object side and a negative meniscus lens L52 having a concave surface facing the object side. The negative meniscus lens L52 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The variable magnification optical system according to the present example includes the image side lens surface (surface number 3) of the biconvex positive lens L12 of the first lens group G1 and the object side of the positive meniscus lens L51 of the fifth lens group G5. An antireflection film described later is formed on the lens surface (surface number 29).

  With the above-described configuration, in the zoom optical system according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 and the second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The air gap between G2 and the third lens group G3, the air gap between the third lens group G3 and the fourth lens group G4, and the air gap between the fourth lens group G4 and the fifth lens group G5 are changed. The first lens group G1 to the fourth lens group G4 move toward the object side along the optical axis. The position of the fifth lens group G5 in the optical axis direction is fixed during zooming. The aperture stop S moves to the object side integrally with the fourth lens group G4 during zooming.

Specifically, during zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the fourth lens group. The air space between G4 and the fifth lens group G5 increases. The air gap between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state to the first intermediate focal length state, decreases from the first intermediate focal length state to the second intermediate focal length state, and second It increases from the intermediate focal length state to the telephoto end state. During zooming, the air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the first intermediate focal length state and increases from the first intermediate focal length state to the second intermediate focal length state. , And decreases from the second intermediate focal length state to the telephoto end state.
Table 3 below lists values of specifications of the variable magnification optical system according to the present example.

(Table 3) Third Example
[Surface data]
Surface number r d nd νd
Object ∞

1 142.4935 1.6350 1.950000 29.37
2 42.2502 8.5971 1.497820 82.57
3 -244.5599 0.1000
4 43.5280 4.7901 1.834810 42.73
5 290.5464 Variable

* 6 500.0000 1.0000 1.851350 40.10
7 9.0471 4.3168
8 -20.3544 1.0000 1.903660 31.27
9 42.4575 0.7313
10 28.0881 4.0634 1.808090 22.74
11 -12.5975 1.0000 1.883000 40.66
12 -38.6924 Variable

13 (Aperture S) ∞ Variable

14 31.6163 1.0000 1.883000 40.66
15 15.7262 3.3464 1.593190 67.90
16 -39.3012 variable

17 13.5000 9.6782 1.717000 47.98
18 -38.7323 1.0000 1.883000 40.66
19 11.8099 2.0000
20 19.9976 3.2554 1.516800 63.88
21 -12.0110 1.0000 1.850260 32.35
22 -20.9691 1.5000
23 -39.8308 1.0000 1.950000 29.37
24 10.4776 3.5701 1.672700 32.19
25 -30.1182 0.5349
26 36.6513 5.1773 1.581440 40.98
27 -8.5118 1.0000 1.820800 42.71
* 28 -28.2741 Variable

29 -40.0000 1.9141 1.497820 82.57
30 -18.1052 1.0000 1.834410 37.28
* 31 -22.6207 BF
Image plane ∞

[Aspherical data]
6th surface κ -3.81950
A4 4.21558E-05
A6 -2.17082E-07
A8 -2.45102E-09
A10 5.51411E-11
A12 -2.85950E-13

No. 28 κ 1.0000
A4 -6.70317E-05
A6 -2.82990E-07
A8 5.39592E-10
A10 -1.47007E-11
A12 0.00000

31st surface κ 1.00000
A4 2.67692E-05
A6 2.52197E-08
A8 -6.04092E-10
A10 0.00000
A12 0.00000

[Various data]
Scaling ratio 14.13

W T
f 9.27 to 130.95
FNO 4.11 to 5.71
ω 42.66-3.37 °
Y 8.00-8.00
TL 113.35-167.85

W M1 M2 M3 T
f 9.27001 17.98649 60.50024 89.50040 130.95047
ω 42.66459 22.98882 7.25983 4.93130 3.37079
FNO 4.11 5.12 5.73 5.75 5.71
φ 8.59 8.59 9.57 10.18 11.03
d5 2.10000 14.22823 35.96983 41.57489 45.70436
d12 24.57776 16.27840 5.38702 3.71762 2.20000
d13 5.01075 3.17327 4.36075 3.46075 1.80000
d16 2.25000 4.08748 2.90000 3.80000 5.46075
d28 1.15583 11.01481 29.01229 32.10086 34.42483
BF 14.04945 14.04946 14.04979 14.04987 14.04999

[Lens group data]
Group start surface f
1 1 67.49208
2 6 -9.52181
3 14 41.09622
4 17 53.39457
5 29 147.67270

[Conditional expression values]
(1) (-f2) / fw = 1.027
(2) f1 / ft = 0.515
(3) f1 / (− f2) = 7.088
(4) (−f2) /ft=0.073
(5) f1 / fw = 7.281

FIGS. 8A, 8B, and 8C are respectively a wide-angle end state, a first intermediate focal length state, and a second intermediate focus of the variable magnification optical system according to the third example of the present application. It is an aberration diagram at the time of focusing on an object at infinity in the distance state.
FIGS. 9A and 9B are graphs showing various aberrations when focusing on an object at infinity in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the third example of the present application, respectively. It is.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

(Fourth embodiment)
10 (a), 10 (b), 10 (c), 10 (d), and 10 (e) are respectively the wide-angle end state of the variable magnification optical system according to the fourth example of the present application, It is sectional drawing in a 1st intermediate | middle focal distance state, a 2nd intermediate | middle focal distance state, a 3rd intermediate | middle focal distance state, and a telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a positive refractive power. The lens group G3 includes a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. Become.
The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a biconcave negative lens L24. The cemented lens. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 is composed of a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32 in order from the object side. An aperture stop S is provided on the object side of the third lens group G3.
In order from the object side, the fourth lens group G4 includes a cemented lens of a positive meniscus lens L41 having a convex surface directed toward the object side and a negative meniscus lens L42 having a convex surface directed toward the object side, a biconvex positive lens L43, and an object. A cemented lens with a negative meniscus lens L44 with a concave surface facing the side, a biconcave negative lens L45, a cemented lens with a biconvex positive lens L46 and a negative meniscus lens L47 with a concave surface facing the object side Become. The negative lens L45 is a glass mold aspheric lens having an aspheric lens surface on the object side, and the negative meniscus lens L47 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The fifth lens group G5 includes, in order from the object side, a cemented lens including a positive meniscus lens L51 having a concave surface facing the object side and a negative meniscus lens L52 having a concave surface facing the object side. The negative meniscus lens L52 is a glass mold aspheric lens having an aspheric lens surface on the image side.

  The variable magnification optical system according to the present example includes the image side lens surface (surface number 7) of the negative meniscus lens L21 of the second lens group G2 and the object side of the biconcave negative lens L22 of the second lens group G2. An antireflection film described later is formed on the lens surface (surface number 8).

With the above-described configuration, in the zoom optical system according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 and the second lens group at the time of zooming from the wide-angle end state to the telephoto end state. The air gap between G2 and the third lens group G3, the air gap between the third lens group G3 and the fourth lens group G4, and the air gap between the fourth lens group G4 and the fifth lens group G5 are changed. The first lens group G1 to the fourth lens group G4 move along the optical axis.
Specifically, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side during zooming. The second lens group G2 moves toward the object side from the wide-angle end state to the second intermediate focal length state, moves toward the image side from the second intermediate focal length state to the third intermediate focal length state, and is in the third intermediate focal length state. To the telephoto end state. The position of the fifth lens group G5 in the optical axis direction is fixed during zooming. The aperture stop S moves to the object side integrally with the fourth lens group G4 during zooming.

Thereby, at the time of zooming, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the fourth lens group G4. And the fifth lens group G5 increase in air space. The air gap between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state to the first intermediate focal length state, decreases from the first intermediate focal length state to the second intermediate focal length state, and second It increases from the intermediate focal length state to the telephoto end state. During zooming, the air gap between the aperture stop S and the third lens group G3 decreases from the wide-angle end state to the first intermediate focal length state and increases from the first intermediate focal length state to the second intermediate focal length state. , And decreases from the second intermediate focal length state to the telephoto end state.
Table 4 below lists values of specifications of the variable magnification optical system according to the present example.

(Table 4) Fourth Example
[Surface data]
Surface number r d nd νd
Object ∞

1 128.2103 1.6350 1.950000 29.37
2 42.8046 8.6432 1.497820 82.57
3 -200.0000 0.1000
4 42.6819 4.9663 1.816000 46.59
5 290.0414 Variable

* 6 500.0000 1.0000 1.851350 40.10
7 9.6706 3.8612
8 -31.6340 1.0000 1.883000 40.66
9 50.5774 0.3860
10 20.2802 4.0969 1.808090 22.74
11 -12.7389 1.0000 1.902650 35.73
12 182.6358 Variable

13 (Aperture S) ∞ Variable
14 22.0943 1.0000 1.883000 40.66
15 12.0211 3.4295 1.593190 67.90
16 -54.4618 Variable

17 13.5315 7.0129 1.816000 46.59
18 20.2242 1.0000 1.850260 32.35
19 10.9126 2.0000
20 18.6799 3.1628 1.516800 63.88
21 -12.1205 1.0000 1.850260 32.35
22 -21.9214 1.5000
* 23 -2373.2040 1.0000 1.806100 40.71
24 15.4976 2.3426
25 18.1342 5.9256 1.567320 42.58
26 -8.0000 1.0000 1.851350 40.10
* 27 -22.6238 Variable

28 -75.6072 2.0606 1.497820 82.57
29 -18.0744 1.0000 1.834410 37.28
* 30 -25.8110 BF

Image plane ∞

[Aspherical data]
6th surface κ -9.00000
A4 1.14894E-05
A6 2.79933E-07
A8 -1.11589E-08
A10 1.42629E-10
A12 -6.44930E-13

23rd surface κ 1.00000
A4 -3.10495E-05
A6 4.64001E-07
A8 -2.52074E-09
A10 1.73753E-10
A12 0.00000

27th surface κ 1.0000
A4 -5.63578E-05
A6 -8.97938E-08
A8 1.47935E-09
A10 -1.36135E-11
A12 0.00000

30th surface κ 1.00000
A4 2.81743E-05
A6 -2.96842E-08
A8 -7.80468E-10
A10 0.00000
A12 0.00000

[Various data]
Scaling ratio 14.13

W T
f 10.30 to 145.50
FNO 4.12 to 5.77
ω 39.65 to 3.02 °
Y 8.00-8.00
TL 107.35-157.35

W M1 M2 M3 T
f 10.30004 17.99586 60.49785 100.49280 145.50011
ω 39.65487 23.02121 7.21558 4.36760 3.01679
FNO 4.12 4.94 5.67 5.75 5.77
φ 8.34 8.34 9.08 9.22 10.26
d5 2.10000 12.12447 32.02336 38.52508 41.21393
d12 22.23850 16.63220 7.10168 3.99200 2.20000
d13 3.91359 2.69844 3.58860 3.47054 1.80000
d16 3.65694 4.87210 3.98194 4.10000 5.77054
d27 1.26857 9.13237 25.54504 27.42933 32.19314
BF 14.04952 14.04918 14.04790 14.04914 14.04886

[Lens group data]
Group start surface f
1 1 62.23195
2 6 -9.03822
3 14 37.53030
4 17 49.24516
5 28 130.00164

[Conditional expression values]
(1) (−f2) /fw=0.877
(2) f1 / ft = 0.428
(3) f1 / (− f2) = 6.885
(4) (−f2) /ft=0.062
(5) f1 / fw = 6.042

11 (a), 11 (b), and 11 (c) respectively show the wide-angle end state, the first intermediate focal length state, and the second intermediate focus of the zoom optical system according to the fourth example of the present application. It is an aberration diagram at the time of focusing on an object at infinity in the distance state.
FIGS. 12A and 12B are graphs showing various aberrations when focusing on an object at infinity in the third intermediate focal length state and the telephoto end state of the variable magnification optical system according to the fourth example of the present application, respectively. It is.

  From the respective aberration diagrams, it can be seen that the variable magnification optical system according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state.

  Here, an antireflection film (also referred to as a multilayer broadband antireflection film) used in the variable magnification optical system according to the embodiment of the present application will be described. FIG. 16 is a diagram illustrating an example of a film configuration of the antireflection film. The antireflection film 101 is composed of seven layers and is formed on the optical surface of the optical member 102 such as a lens. The first layer 101a is formed of aluminum oxide deposited by a vacuum deposition method. Further, a second layer 101b made of a mixture of titanium oxide and zirconium oxide deposited by a vacuum deposition method is further formed on the first layer 101a. Further, a third layer 101c made of aluminum oxide deposited by a vacuum deposition method is formed on the second layer 101b, and titanium oxide and zirconium oxide deposited by a vacuum deposition method are formed on the third layer 101c. A fourth layer 101d made of the mixture is formed. Furthermore, a fifth layer 101e made of aluminum oxide deposited by vacuum deposition is formed on the fourth layer 101d, and titanium oxide and zirconium oxide deposited by vacuum deposition on the fifth layer 101e. A sixth layer 101f made of the mixture is formed.

  Then, a seventh layer 101g made of a mixture of magnesium fluoride and silica is formed on the sixth layer 101f formed in this way by a wet process, and the antireflection film 101 of this embodiment is formed. For the formation of the seventh layer 101g, a sol-gel method which is a kind of wet process is used. The sol-gel method is a method in which a sol obtained by mixing raw materials is made into a non-flowable gel by hydrolysis / polycondensation reaction, etc., and this gel is heated and decomposed to obtain a product, In the production of an optical thin film, a film can be formed by applying an optical thin film material sol on the optical surface of an optical member and forming a gel film by drying and solidifying. The wet process is not limited to the sol-gel method, and a method of obtaining a solid film without going through a gel state may be used.

Thus, the first layer 101a to the sixth layer 101f of the antireflection film 101 are formed by electron beam evaporation which is a dry process, and the seventh layer 101g which is the uppermost layer is prepared by a hydrofluoric acid / magnesium acetate method. It is formed by the following procedure by a wet process using the prepared sol solution. First, an aluminum oxide layer to be the first layer 101a, a titanium oxide-zirconium oxide mixed layer to be the second layer 101b, a third layer on the lens film formation surface (the optical surface of the optical member 102 described above) in advance using a vacuum deposition apparatus, An aluminum oxide layer to be the layer 101c, a titanium oxide-zirconium oxide mixed layer to be the fourth layer 101d, an aluminum oxide layer to be the fifth layer 101e, and a titanium oxide-zirconium oxide mixed layer to be the sixth layer 101f are formed in this order. And after taking out the optical member 102 from a vapor deposition apparatus, the thing which added the silicon alkoxide to the sol liquid prepared by the hydrofluoric acid / magnesium acetate method is apply | coated by the spin coat method, The magnesium fluoride used as the 7th layer 101g A layer made of a mixture of silica and silica is formed. The reaction formula when prepared by the hydrofluoric acid / magnesium acetate method is shown in the following formula (a).
(A) 2HF + Mg (CH3COO) 2 → MgF2 + 2 + CH3COOH
The sol solution used for the film formation is used for film formation after mixing raw materials and subjecting to an autoclave at 140 ° C. for 24 hours at a high temperature and pressure. The optical member 102 is completed by heat treatment at 160 ° C. for 1 hour in the air after the seventh layer 101g is formed. By using such a sol-gel method, the seventh layer 101g is formed by depositing particles having a size of several nm to several tens of nm leaving a void.

  The optical performance of the optical member having the antireflection film 101 formed as described above will be described with reference to spectral characteristics shown in FIG.

  The optical member (lens) having the antireflection film according to this embodiment is formed under the conditions shown in Table 5 below. Here, Table 5 shows that the reference wavelength is λ, and the layers 101a (first layer) to 101g (seventh layer) of the antireflection film 101 when the refractive index of the substrate (optical member) is 1.62, 1.74, and 1.85. The optical film thickness of each layer is determined. In Table 5, aluminum oxide is represented by Al2O3, a mixture of titanium oxide and zirconium oxide is represented by ZrO2 + TiO2, and a mixture of magnesium fluoride and silica is represented by MgF2 + SiO2.

(Table 5)
Substance Refractive index Optical film thickness Optical film thickness Optical film thickness
Medium air 1
7th layer MgF2 + SiO2 1.26 0.268λ 0.271λ 0.269λ
6th layer ZrO2 + TiO2 2.12 0.057λ 0.054λ 0.059λ
5th layer Al2O3 1.65 0.171λ 0.178λ 0.162λ
4th layer ZrO2 + TiO2 2.12 0.127λ 0.13λ 0.158λ
3rd layer Al2O3 1.65 0.122λ 0.107λ 0.08λ
Second layer ZrO2 + TiO2 2.12 0.059λ 0.075λ 0.105λ
1st layer Al2O3 1.65 0.257λ 0.03λ 0.03λ
Refractive index of substrate 1.62 1.74 1.85

  FIG. 17 shows the spectral characteristics when a light beam is perpendicularly incident on an optical member in which the reference wavelength λ is 550 nm and the optical film thickness of each layer of the antireflection film 101 is designed in Table 5.

  From FIG. 17, it can be seen that the optical member having the antireflection film 101 designed with the reference wavelength λ of 550 nm can suppress the reflectance to 0.2% or less over the entire wavelength range of 420 nm to 720 nm. Further, even in the optical member having the antireflection film 101 in which each optical film thickness is designed with the reference wavelength λ as d line (wavelength 587.6 nm) in Table 5, the spectral characteristics are hardly affected, and the reference shown in FIG. Spectral characteristics substantially equivalent to those when the wavelength λ is 550 nm.

  Next, a modified example of the antireflection film will be described. This antireflection film consists of five layers, and similarly to Table 5, the optical film thickness of each layer with respect to the reference wavelength λ is designed under the conditions shown in Table 6 below. In this modification, the above-described sol-gel method is used for forming the fifth layer.

(Table 6)
Material Refractive index Optical film thickness Optical film thickness Medium Air 1
5th layer MgF2 + SiO2 1.26 0.275λ 0.269λ
4th layer ZrO2 + TiO2 2.12 0.045λ 0.043λ
3rd layer Al2O3 1.65 0.212λ 0.217λ
Second layer ZrO2 + TiO2 2.12 0.077λ 0.066λ
1st layer Al2O3 1.65 0.288λ 0.290λ
Refractive index of substrate 1.46 1.52

  FIG. 18 shows the spectral characteristics when light enters perpendicularly to an optical member having an antireflection film in which the optical film thickness is designed with the refractive index of the substrate being 1.52 and the reference wavelength λ being 550 nm in Table 6. Yes. From FIG. 18, it can be seen that the antireflection film of this modification has a reflectance of 0.2% or less over the entire wavelength range of 420 nm to 720 nm. In Table 6, even an optical member having an antireflection film whose optical film thickness is designed with the reference wavelength λ as the d-line (wavelength 587.6 nm) hardly affects the spectral characteristics, and the spectral characteristics shown in FIG. Has almost the same characteristics.

  FIG. 19 shows the spectral characteristics when the incident angles of the light rays to the optical member having the spectral characteristics shown in FIG. 18 are 30, 45, and 60 degrees, respectively. 18 and 19 do not show the spectral characteristics of the optical member having the antireflection film whose refractive index is 1.46 shown in Table 6, but the refractive index of the substrate is almost equal to 1.52. Needless to say, it has the following spectral characteristics.

  For comparison, FIG. 20 shows an example of an antireflection film formed only by a dry process such as a conventional vacuum deposition method. FIG. 20 shows spectral characteristics when a light beam is perpendicularly incident on an optical member designed with an antireflection film configured under the conditions shown in Table 7 below with a refractive index of 1.52 of the same substrate as in Table 6. FIG. 21 shows spectral characteristics when the incident angles of light rays to the optical member having the spectral characteristics shown in FIG. 20 are 30, 45, and 60 degrees, respectively.

(Table 7)
Material Refractive index Optical film thickness Medium Air 1
7th layer MgF2 1.39 0.243λ
6th layer ZrO2 + TiO2 2.12 0.119λ
5th layer Al2O3 1.65 0.057λ
4th layer ZrO2 + TiO2 2.12 0.220λ
3rd layer Al2O3 1.65 0.064λ
Second layer ZrO2 + TiO2 2.12 0.057λ
1st layer Al2O3 1.65 0.193λ
Refractive index of substrate 1.52

  When the spectral characteristics of the optical member having the antireflection film according to this embodiment shown in FIGS. 17 to 19 are compared with the spectral characteristics of the conventional example shown in FIGS. 20 and 21, the antireflection film according to this embodiment is compared. It can be seen that has a lower reflectivity at any angle of incidence and a lower reflectivity over a wider band.

  Next, examples in which the antireflection films shown in Tables 5 and 6 are applied to the first to fourth examples of the present application will be described.

  In the variable magnification optical system of the first example, the refractive index of the negative meniscus lens L21 of the second lens group G2 is nd = 1.851350 as shown in Table 1, and the biconcave of the second lens group G2 Since the refractive index of the shaped negative lens L22 is nd = 1.883000, the antireflective film 101 corresponding to the refractive index of the substrate corresponding to the refractive index of the substrate on the image surface side lens surface of the negative meniscus lens L21 (see Table 5). ) And an antireflection film 101 (see Table 5) corresponding to a refractive index of the substrate of 1.85 is used on the object-side lens surface of the biconcave negative lens L22 to reflect light from each lens surface. , And ghost and flare can be reduced.

  In the variable magnification optical system of the second example, the refractive index of the positive meniscus lens L13 of the first lens group G1 is nd = 1.729160 as shown in Table 2, so that the object side of the positive meniscus lens L13 is The antireflective film 101 (see Table 5) corresponding to the refractive index of the substrate corresponding to 1.74 is used for the lens surface, and the refractive index of the substrate corresponds to 1.74 corresponding to the lens surface on the image plane side in the positive meniscus lens L13. By using the antireflection film 101 (see Table 5), the reflected light from each lens surface can be reduced, and ghost and flare can be reduced.

  In the zoom optical system of the third example, the refractive index of the biconvex positive lens L12 of the first lens group G1 is nd = 1.497820 as shown in Table 3, and the fifth lens group G5 Since the refractive index of the positive meniscus lens L51 is nd = 1.497820, the antireflective film corresponding to the refractive index of the substrate corresponding to 1.52 on the image surface side lens surface of the biconvex positive lens L12 (table) 6) and an antireflection film (see Table 6) corresponding to a refractive index of the substrate of 1.52 is used on the object-side lens surface of the positive meniscus lens L51 to reduce the reflected light from each lens surface. Ghost and flare can be reduced.

  In the zoom optical system of the fourth example, the refractive index of the negative meniscus lens L21 of the second lens group G2 is nd = 1.851350 as shown in Table 4, and the biconcave of the second lens group G2 Since the refractive index of the shaped negative lens L22 is nd = 1.883000, the antireflective film 101 corresponding to the refractive index of the substrate corresponding to the refractive index of the substrate on the image surface side lens surface of the negative meniscus lens L21 (see Table 5). ) And an antireflection film 101 (see Table 5) corresponding to a refractive index of the substrate of 1.85 is used on the object-side lens surface of the biconcave negative lens L22 to reflect light from each lens surface. , And ghost and flare can be reduced.

According to each of the above embodiments, a variable power optical system having a high zoom ratio, a small size, and high optical performance can be realized.
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 adopted as appropriate as long as the optical performance of the variable magnification optical system of the present application is not impaired.

  A numerical example of the variable magnification optical system of the present application is shown as having a five-group configuration, but the present application is not limited to this, and constitutes a variable magnification optical system of other group configurations (for example, six groups, seven groups, etc.). You can also. 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 variable magnification optical system 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 variable magnification optical system 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 for focusing from an object at infinity to a near object. It is good also as a structure moved to an axial direction. In particular, it is preferable that at least part of the second lens group, at least part of the third lens group, at least part of the fourth lens group, or at least part of the fifth lens group be the 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.

  Further, in the variable magnification optical system of the present application, any lens group or a part thereof is moved as a vibration-proof lens group so as to include a component in a direction perpendicular to the optical axis, or a surface including the optical axis A configuration in which image blur caused by camera shake or the like is corrected by rotationally moving (swinging) inward is also possible. In particular, in the variable magnification optical system of the present application, it is preferable that at least a part of the third lens group, at least a part of the fourth lens group, or at least a part of the fifth lens group be an anti-vibration lens group.

  The lens surface of the lens constituting the variable magnification optical system 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 variable magnification optical system of the present application, the aperture stop is preferably arranged in the third lens group or in the vicinity of the third lens group, and the role of the aperture stop is replaced by a lens frame without providing a member. Also good.

Next, a camera equipped with the variable magnification optical system of the present application will be described with reference to FIG.
FIG. 13 is a diagram illustrating a configuration of a camera including the variable magnification optical system of the present application.
As shown in FIG. 13, the camera 1 is a so-called mirrorless camera of an interchangeable lens type that includes the variable magnification optical system according to the first example 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 optical system according to the first embodiment mounted as the photographing lens 2 on the camera 1 is a zoom optical system having a high zoom ratio, a small size, and high optical performance. Therefore, the present camera 1 can achieve downsizing and high optical performance while having a high zoom ratio. Even if a camera equipped with the variable magnification optical system according to the second to fourth examples as the photographing lens 2 is configured, the same effect as the camera 1 can be obtained. Further, even when the variable magnification optical system according to each of the above embodiments is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a finder optical system, the same effect as the camera 1 can be obtained. it can.

Finally, the outline of the manufacturing method of the variable magnification optical system of this application is demonstrated based on FIG.
The variable power optical system manufacturing method shown in FIG. 14 has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. A variable magnification optical system manufacturing method including a third lens group, a fourth lens group having a positive refractive power, and a fifth lens group, and includes the following steps S1 to S3.

Step S1: An antireflection film is provided on at least one of the optical surfaces in the first lens group, the second lens group, and the fifth lens group, and the antireflection film has at least one layer formed by using a wet process. To include layers.

Step S2: The first lens group and the second lens group satisfy the following conditional expressions (1) and (2), and the respective lens groups are sequentially arranged in the lens barrel from the object side.
(1) 0.650 <(− f2) / fw <1.180
(2) 0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

  Step S3: By providing a known moving mechanism in the lens barrel, the distance between the first lens group and the second lens group, the second lens group and the first lens group at the time of zooming from the wide-angle end state to the telephoto end state. The distance between the third lens group, the distance between the third lens group and the fourth lens group, and the distance between the fourth lens group and the fifth lens group are changed. At this time, the position of the fifth lens group is fixed.

  According to such a method for manufacturing a variable magnification optical system of the present application, a variable magnification optical system having a high zoom ratio, a small size, and high optical performance can be manufactured.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group S Aperture stop I Image surface 101 Antireflection film 101a 1st layer 101b 2nd layer 101c 3rd layer 101d 4th Layer 101e fifth layer 101f sixth layer 101g seventh layer 102 optical member

Claims (22)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A group and a fifth lens group,
An antireflection film is provided on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group, and the antireflection film is a layer formed using a wet process. At least one layer,
At the time of zooming from the wide angle end state to the telephoto end state, the distance between the first lens group and the second lens group, the distance between the second lens group and the third lens group, the third lens group and the The distance between the fourth lens group and the distance between the fourth lens group and the fifth lens group are changed, and the position of the fifth lens group is fixed;
A zoom optical system characterized by satisfying the following conditional expression:
0.650 <(− f2) / fw <1.180
0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group The antireflection film is a multilayer film,
2. The variable magnification optical system according to claim 1, wherein the layer formed by using the wet process is a layer on the most surface side of the layers constituting the multilayer film.   The nd is 1.30 or less, where nd is a refractive index with respect to d-line (wavelength λ = 587.6 nm) of a layer formed by the wet process. The zoom optical system according to 1. Having an aperture stop,
4. The variable magnification optical system according to claim 1, wherein the optical surface provided with the antireflection film is a concave lens surface when viewed from the aperture stop. 5. .   5. The variable magnification optical system according to claim 4, wherein the concave lens surface when viewed from the aperture stop is an image surface side lens surface of a lens in the first lens group.   5. The variable magnification optical system according to claim 4, wherein the concave lens surface viewed from the aperture stop is an object side lens surface of a lens in the first lens group.   5. The variable magnification optical system according to claim 4, wherein the concave lens surface viewed from the aperture stop is an image surface side lens surface of the first lens from the object side in the second lens group. .   5. The variable magnification optical system according to claim 4, wherein the concave lens surface as viewed from the aperture stop is an object side lens surface of a lens in the fifth lens group.   4. The variable magnification optical system according to claim 1, wherein the optical surface provided with the antireflection film is a concave lens surface when viewed from the object side. 5.   10. The variable magnification optical system according to claim 9, wherein the lens surface having a concave shape when viewed from the object side is an image surface side lens surface of a lens in the first lens group.   10. The variable magnification optical system according to claim 9, wherein the concave lens surface when viewed from the object side is an object side lens surface of a second lens from the object side in the second lens group. The zoom lens system according to any one of claims 1 to 11, wherein the following conditional expression is satisfied.
5.300 <f1 / (− f2) <8.500
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group   The zoom optical system according to any one of claims 1 to 12, wherein the third lens group moves toward the object side during zooming from the wide-angle end state to the telephoto end state.   The zoom optical system according to any one of claims 1 to 13, wherein the first lens unit moves toward the object side during zooming from the wide-angle end state to the telephoto end state.   The variable power optical system according to any one of claims 1 to 14, wherein the fifth lens group has a positive refractive power.   The distance between the first lens group and the second lens group increases during zooming from the wide-angle end state to the telephoto end state. Variable magnification optical system.   The distance between the second lens group and the third lens group decreases during zooming from the wide-angle end state to the telephoto end state. Variable magnification optical system.   18. The distance between the fourth lens group and the fifth lens group increases during zooming from the wide-angle end state to the telephoto end state. 18. Variable magnification optical system. The variable magnification optical system according to any one of claims 1 to 18, wherein the following conditional expression is satisfied.
0.040 <(− f2) / ft <0.092
However,
ft: focal length of the variable magnification optical system in the telephoto end state f2: focal length of the second lens group The zoom lens system according to any one of claims 1 to 19, wherein the following conditional expression is satisfied.
5.000 <f1 / fw <7.800
However,
fw: focal length of the variable magnification optical system in the wide-angle end state f1: focal length of the first lens group   An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 20. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power A variable magnification optical system having a group and a fifth lens group,
An antireflection film is provided on at least one of the optical surfaces of the first lens group, the second lens group, and the fifth lens group, and the antireflection film has at least one layer formed by a wet process. To include layers,
The first lens group and the second lens group satisfy the following conditional expression:
At the time of zooming from the wide angle end state to the telephoto end state, the distance between the first lens group and the second lens group, the distance between the second lens group and the third lens group, the third lens group and the A variable power optical system characterized in that the distance between the fourth lens group and the distance between the fourth lens group and the fifth lens group are changed so that the position of the fifth lens group is fixed. Manufacturing method.
0.650 <(− f2) / fw <1.180
0.300 <f1 / ft <0.555
However,
fw: focal length of the variable magnification optical system in the wide-angle end state ft: focal length of the variable magnification optical system in the telephoto end state f1: focal length of the first lens group f2: focal length of the second lens group

Images