JP2011164550A - Variable magnification optical system, optical apparatus, and method for manufacturing variable magnification optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a variable magnification optical system that has satisfactory optical performance; an optical apparatus; and a method for manufacturing the variable magnification optical system. <P>SOLUTION: The variable magnification optical system includes, in order from an object side: a first lens group G1 of positive refractive power; a second lens group G2 of negative refractive power; a third lens group G3 of positive refractive power; a fourth lens group G4 of negative refractive power; and a fifth lens group G5 of positive refractive power. In the variable magnification optical system, when performing variable power from a wide-angle-end state to a telephoto-end state, the interval between the first and second lens groups G1 and G2 vary, the interval between the second and third lens groups G2 and G3 vary, the interval between the third and fourth lens groups G3 and G4 vary, and the interval between the fourth and fifth lens groups G4 and G5 vary. In the variable magnification optical system, it is possible to adjust a position by eccentrically shifting the fifth lens group G5 so as to include a direction orthogonal to an optical axis, and a predetermined conditional expression is satisfied. <P>COPYRIGHT: (C)2011,JPO&INPIT

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, a variable magnification optical system suitable for a photographic camera, an electronic still camera, a video camera, and the like has been proposed (see, for example, Patent Document 1).

JP 2006-227526 A

However, the conventional variable magnification optical system has a problem that it cannot achieve good optical performance. Further, the conventional variable magnification optical system has a problem that the imaging performance deteriorates when an eccentric error occurs.
Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a variable magnification optical system, an optical apparatus, and a method for manufacturing the variable magnification optical system having good optical performance.

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 negative refractive power A group and a fifth lens group having a positive refractive power,
Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, The distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the fifth lens group changes,
The fifth lens group is configured to be shift decentered so as to include a direction orthogonal to the optical axis and to adjust the position.
Provided is a variable magnification optical system characterized by satisfying the following conditional expressions (1) and (2).
(1) 0.65 <(− f2) / f3 <0.90
(2) 0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth 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 negative refractive power A variable magnification optical system having a group and a fifth lens group having a positive refractive power,
The second lens group, the third lens group, and the fourth lens group satisfy the following conditional expressions (1) and (2):
Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, An interval between the third lens group and the fourth lens group is changed, and an interval between the fourth lens group and the fifth lens group is changed;
Provided is a variable magnification optical system manufacturing method characterized in that the fifth lens group can be shifted and decentered so as to include a direction orthogonal to the optical axis to adjust the position.
(1) 0.65 <(− f2) / f3 <0.90
(2) 0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth lens group

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the variable magnification optical system, optical apparatus, and variable magnification optical system which have favorable optical performance can be provided.

It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 1st Example of this application. The structure of the adjustment mechanism of the variable magnification optical system which concerns on 1st Example of this application is shown typically, (a) is sectional drawing, (b) is A of 3rd holding member and 3rd sliding member in (a). -A 'sectional drawing, (c) is the figure which looked at the 5th holding member in (a) from the image side. (A) and (b) are various aberration diagrams at the time of focusing at infinity in the wide-angle end state of the variable magnification optical system according to the first example of the present application, and an image with respect to a rotation blur of 0.64 °. FIG. 5 is a meridional lateral aberration diagram when blur correction is performed. FIG. 6 is a diagram illustrating various aberrations during focusing at infinity in the intermediate focal length state of the variable magnification optical system according to the first example of the present application. (A) and (b) are various aberration diagrams at the time of focusing on infinity in the telephoto end state of the variable magnification optical system according to the first example of the present application, and an image with respect to a rotational blur of 0.29 °. FIG. 5 is a meridional lateral aberration diagram when blur correction is performed. (A), (b), and (c) are each in the third lens group when defocus error occurs in the variable magnification optical system according to the first example of the present application, and when focusing at infinity in the telephoto end state. Fig. 6 shows a meridional lateral aberration diagram when the positive lens L31 is shifted decentered, an astigmatism diagram when the entire fifth lens group is shifted decentered (shifted up), and a shift decentered (shifted down) the entire fifth lens group. It is an astigmatism figure when letting it be. It is sectional drawing which shows the lens structure of the variable magnification optical system which concerns on 2nd Example of this application. (A) and (b) are various aberration diagrams at the time of focusing at infinity in the wide-angle end state of the variable magnification optical system according to the second example of the present application, and an image with respect to a rotation blur of 0.64 °. FIG. 5 is a meridional lateral aberration diagram when blur correction is performed. It is an aberration diagram at the time of infinity focusing in the intermediate focal length state of the variable magnification optical system which concerns on 2nd Example of this application. (A) and (b) are various aberration diagrams at the time of focusing on infinity in the telephoto end state of the variable magnification optical system according to the second example of the present application, and an image with respect to a rotational blur of 0.29 °. FIG. 5 is a meridional lateral aberration diagram when blur correction is performed. (A), (b), and (c) are respectively in the third lens group when defocus error occurs in the variable magnification optical system according to the second example of the present application, and when focusing at infinity in the telephoto end state. , A meridional lateral aberration diagram when the cemented lens of the negative meniscus lens L32 and the positive lens L33 is decentered, astigmatism diagram when the entire fifth lens group is decentered (shift up), and the fifth lens. It is an astigmatism diagram when the entire group is shifted decentered (shifted down). 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 manufacturing method of the variable magnification optical system of this application.

Hereinafter, the variable magnification optical system, the optical apparatus, and the 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, and a negative lens power. A fourth lens group having a refractive power of 5 and a fifth lens group having a positive refractive power, and at the time of zooming from the wide-angle end state to the telephoto end state, the first lens group and the second lens group The distance between the second lens group and the third lens group is changed, the distance between the third lens group and the fourth lens group is changed, and the fourth lens group and the fourth lens group are changed. The distance between the fifth lens group is changed, and the fifth lens group can be shifted and decentered so as to include a direction orthogonal to the optical axis. The following conditional expression (1) , (2) is satisfied.
(1) 0.65 <(− f2) / f3 <0.90
(2) 0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth lens group

  The variable magnification optical system of the present application includes a direction in which the fifth lens group is orthogonal to the optical axis, and the image formation performance is deteriorated due to the occurrence of a decentration error in the variable magnification optical system, particularly the image plane asymmetry in the telephoto end state. Thus, it can correct | amend favorably by carrying out shift eccentricity and performing position adjustment.

Conditional expression (1) is a conditional expression for defining the focal length of the third lens group with respect to the focal length of the second lens group. The zooming optical system of the present application can satisfy the conditional expression (1) to achieve good optical performance and ensure a predetermined zooming ratio.
If the corresponding value of the conditional expression (1) of the variable magnification optical system of the present application exceeds the upper limit value, the refractive power of the third lens unit increases, and it becomes difficult to correct spherical aberration in the telephoto end state, which is not preferable. . In order to secure the effect of the present application, it is preferable to set the upper limit value of conditional expression (1) to 0.80, and thereby better optical performance can be realized.
On the other hand, if the corresponding value of conditional expression (1) of the variable magnification optical system of the present application is below the lower limit value, the refractive power of the second lens group becomes large, and it becomes difficult to correct astigmatism in the wide-angle end state. Therefore, it is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (1) to 0.67. As a result, the refractive power of the second lens group can be set more appropriately, and fluctuations in coma during zooming can be further reduced.

Conditional expression (2) is a conditional expression for defining the focal length of the fourth lens group with respect to the focal length of the second lens group. The zooming optical system of the present application can satisfy the conditional expression (2) to realize good optical performance and to secure a predetermined zooming ratio.
When the corresponding value of conditional expression (2) of the variable magnification optical system of the present application exceeds the upper limit value, the refractive power of the second lens group becomes small. For this reason, in order to ensure a predetermined zoom ratio, the first lens unit must be extended largely to the object side, which is not preferable because the field curvature and astigmatism after manufacturing deteriorate. In order to secure the effect of the present application, it is preferable to set the upper limit value of conditional expression (2) to 0.75, which can realize better optical performance. In order to further secure the effect of the present application, it is preferable to set the upper limit of conditional expression (2) to 0.65.
On the other hand, if the corresponding value of conditional expression (2) of the variable magnification optical system of the present application is lower than the lower limit value, the refractive power of the fourth lens group becomes small, and it is difficult to correct fluctuations in field curvature at the time of zooming. This is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 0.50. As a result, the refractive power of the second lens group can be set more appropriately, and fluctuations in coma during zooming can be reduced. In order to further secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 0.55.
With the above configuration, a variable magnification optical system having good optical performance can be realized.

Further, it is desirable that the variable magnification optical system of the present application has a configuration capable of performing position adjustment by shifting and decentering at least a part of the third lens group so as to include a direction orthogonal to the optical axis.
The variable magnification optical system according to the present application is capable of deteriorating imaging performance due to the occurrence of a decentration error in the variable magnification optical system, particularly decentration coma in the telephoto end state, and at least a part of the third lens group orthogonal to the optical axis. It is possible to satisfactorily correct by adjusting the position by decentering so as to include the direction to be performed.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (3).
(3) 1.20 <f5 / (− f4) <2.00
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group

Conditional expression (3) is a conditional expression for defining the focal length of the fourth lens group with respect to the focal length of the fifth lens group. The zooming optical system of the present application can satisfy the conditional expression (3) to realize good optical performance and ensure a predetermined zooming ratio.
If the corresponding value of conditional expression (3) of the variable magnification optical system of the present application exceeds the upper limit value, the refractive power of the fourth lens group becomes large, and it is difficult to correct coma in the telephoto end state, which is not preferable. . In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 1.80. As a result, the refractive power of the fourth lens group can be set more appropriately, and coma can be corrected more favorably in the telephoto end state. In order to further secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 1.60.
On the other hand, if the corresponding value of conditional expression (3) of the variable magnification optical system of the present application is less than the lower limit value, the refractive power of the fifth lens unit increases, and it is difficult to correct astigmatism in the wide-angle end state. Therefore, it is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit value of the conditional expression (3) to 1.20, and thereby better optical performance can be realized. In order to further secure the effect of the present application, it is preferable to set the lower limit of conditional expression (3) to 1.40.

Further, it is desirable that the variable magnification optical system of the present application has a configuration in which image blur correction is performed by moving at least a part of the fourth lens group so as to include a direction orthogonal to the optical axis.
In the variable magnification optical system of the present application, the fourth lens group has a smaller number of lenses than the other lens groups, and the lens diameter can be reduced. Therefore, a mechanism for correcting image blur is incorporated. Suitable for Therefore, with the above configuration, it is possible to satisfactorily correct coma variation due to downsizing of the lens barrel and image blur correction.
In the variable magnification optical system of the present application, it is desirable that the fourth lens group has a cemented lens. Thereby, various aberrations such as spherical aberration can be corrected satisfactorily.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (4).
(4) 0.70 <x5 / (− f2) <2.10
However,
f2: Focal length of the second lens group x5: Amount of movement of the fifth lens group on the optical axis during zooming from the wide-angle end state to the telephoto end state

Conditional expression (4) is a conditional expression for defining the focal length of the second lens group with respect to the movement amount of the fifth lens group. The amount of movement when the fifth lens group moves from the image side to the object side is positive. The zooming optical system of the present application can satisfy the conditional expression (4) to realize good optical performance and ensure a predetermined zooming ratio.
If the corresponding value of the conditional expression (4) of the variable magnification optical system of the present application exceeds the upper limit value, the refractive power of the second lens unit increases, and it is difficult to correct astigmatism in the wide-angle end state, which is preferable. Absent. In order to secure the effect of the present application, it is preferable to set the upper limit value of the conditional expression (4) to 1.90, and thereby better optical performance can be realized. In order to further secure the effect of the present application, it is preferable to set the upper limit of conditional expression (4) to 1.70.
On the other hand, when the corresponding value of conditional expression (4) of the variable magnification optical system of the present application is lower than the lower limit value, the moving amount of the fifth lens group becomes small. For this reason, the refractive power of each lens group must be set large, which is not preferable because high-order coma aberration occurs and optical performance deteriorates. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 0.90. Accordingly, the amount of movement of the fifth lens group can be set more appropriately, and higher-order coma aberration can be corrected while ensuring a predetermined zoom ratio. In order to further secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 1.10.

In the zoom optical system according to the present application, it is desirable that the first lens unit moves from the image side to the object side during zooming from the wide-angle end state to the telephoto end state. As a result, it is possible to ensure a predetermined zoom ratio while effectively correcting variations in spherical aberration and field curvature.
In the zoom optical system according to the present application, it is desirable that the fifth lens group moves from the image side to the object side when zooming from the wide-angle end state to the telephoto end state. As a result, it is possible to ensure a predetermined zoom ratio while effectively correcting variations in spherical aberration and field curvature.
In the variable power optical system of the present application, it is desirable to perform focusing from an infinite object point to a short distance object point by moving at least a part of the second lens group along the optical axis. Thereby, it is possible to effectively correct variations such as spherical aberration and curvature of field during focusing.
In the variable magnification optical system of the present application, it is desirable that the second lens group has an aspheric lens. Thereby, distortion and field curvature can be corrected simultaneously in the wide-angle end state.

Further, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (5).
(5) 0.65 <x4 / x3 <0.90
However,
x3: Amount of movement on the optical axis of the third lens group during zooming from the wide-angle end state to the telephoto end state x4: The amount of movement of the fourth lens group during zooming from the wide-angle end state to the telephoto end state Amount of movement on the optical axis

Conditional expression (5) is a conditional expression for defining the movement amount of the third lens group with respect to the movement amount of the fourth lens group. The amount of movement when the third lens group moves from the image side to the object side is positive, and the same applies to the fourth lens group. The zooming optical system according to the present application can satisfy the conditional expression (5) to realize good optical performance and ensure a predetermined zooming ratio.
If the corresponding value of conditional expression (5) of the variable magnification optical system of the present application exceeds the upper limit value, the amount of movement of the third lens unit becomes small, and it becomes difficult to correct spherical aberration in the telephoto end state, which is not preferable. . In order to secure the effect of the present application, it is preferable to set the upper limit value of conditional expression (5) to 0.82, thereby realizing better optical performance. In order to further secure the effect of the present application, it is preferable to set the upper limit of conditional expression (5) to 0.78.
On the other hand, when the corresponding value of conditional expression (5) of the zoom optical system of the present application is below the lower limit value, the amount of movement of the fourth lens group becomes small, and fluctuations in field curvature and coma change during zooming are reduced. This is not preferable because it becomes difficult to correct. In order to further secure the effect of the present application, it is preferable to set the lower limit value of conditional expression (5) to 0.68, which improves the variation in field curvature and coma during zooming. Can be corrected. In order to further secure the effect of the present application, it is preferable to set the lower limit of conditional expression (5) to 0.70.

In the zoom optical system according to the present application, it is preferable that the third lens group includes at least one positive lens component and satisfies the following conditional expression (6).
(6) 1.70 <nd3b <1.85
However,
nd3b: refractive index of the positive lens component having the highest refractive index among the positive lens components in the third lens group with respect to the d-line of the glass material

Conditional expression (6) is a conditional expression for defining the refractive index for the d-line (wavelength λ = 587.6 nm) of the glass material of the positive lens component having the largest refractive index among the positive lens components in the third lens group. It is. The zooming optical system of the present application can satisfy the conditional expression (6) to realize good optical performance and ensure a predetermined zooming ratio.
If the corresponding value of conditional expression (6) of the variable magnification optical system of the present application exceeds the upper limit value, the Petzval sum becomes small, and it becomes difficult to correct curvature of field in the wide-angle end state. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (6) to 1.80. As a result, the refractive index of the glass material can be set more appropriately, and the field curvature can be corrected more favorably in the wide-angle end state.
On the other hand, if the corresponding value of conditional expression (6) of the variable magnification optical system of the present application is below the lower limit value, the curvature of the positive lens component increases, and it becomes difficult to correct higher-order spherical aberration in the telephoto end state. Therefore, it is not preferable. In order to secure the effect of the present application, it is preferable to set the lower limit value of the conditional expression (6) to 1.75, and thereby better optical performance can be realized.

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 good optical performance can be realized.
In addition, 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 having a positive refractive power. And a fourth lens group having negative refracting power and a fifth lens group having positive refracting power, a method of manufacturing a variable magnification optical system, wherein the second lens group and the third lens group And the fourth lens group satisfy the following conditional expressions (1) and (2), and when zooming from the wide-angle end state to the telephoto end state, the first lens group and the second lens group: , The distance between the second lens group and the third lens group is changed, the distance between the third lens group and the fourth lens group is changed, and the fourth lens group and the fourth lens group are changed. The distance from the fifth lens group is changed so that the fifth lens group includes a direction orthogonal to the optical axis. Shifted eccentrically, characterized in that a capable of performing position adjustment configuration.
(1) 0.65 <(− f2) / f3 <0.90
(2) 0.42 <f2 / f4 <0.90
However,
f2: Focal length of the second lens group f3: Focal length of the third lens group f4: Focal length of the fourth lens group By the method of manufacturing a zoom optical system according to the present application, a variable having good optical performance is obtained. A double optical system can be manufactured.

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)
FIG. 1 is a sectional view showing a lens configuration of a variable magnification optical system according to the first example of the present application. FIG. 2 is a diagram schematically illustrating a configuration of an adjustment mechanism provided in the variable magnification optical system according to the present embodiment.
First, the lens shape of the variable magnification optical system according to the present embodiment will be described.
As shown in FIG. 1, the variable magnification optical system according to the present embodiment includes, in order from the object side (not shown), a first lens group G1 having a positive refractive power, and a second lens group G2 having a negative refractive power. The third lens group G3 has a positive refractive power, the fourth lens group G4 has a negative refractive power, and the fifth lens group G5 has 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 negative meniscus lens L22 having a concave surface directed toward the object side, a biconvex positive lens L23, and an object side. And a negative meniscus lens L24 having a concave surface. The negative meniscus lens L21 is an aspheric lens in which an aspheric surface is formed on the object side glass lens surface, and the negative meniscus lens L24 is an aspheric lens in which an aspheric surface is formed on the image side glass lens surface.
The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, an aperture stop S, a cemented lens of a negative meniscus lens L32 having a convex surface facing the object side, and a biconvex positive lens L33. And a biconvex positive lens L34. The aperture stop S is adjacent to the image side of the positive lens L31.
The fourth lens group G4 includes, in order from the object side, a cemented lens of a positive meniscus lens L41 having a concave surface facing the object side and a biconcave negative lens L42, and a negative meniscus lens L43 having a concave surface facing the object side. Become.
The fifth lens group G5 includes, in order from the object side, a biconvex positive lens L51, a cemented lens of a biconvex positive lens L52, and a negative meniscus lens L53 having a concave surface facing the object. The positive lens L51 is an aspheric lens in which an aspheric surface is formed on the object side glass lens surface.

In the zoom optical system according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the second lens group G2 The air gap between the third lens group G3 decreases, the air gap between the third lens group G3 and the fourth lens group G4 increases, and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. In addition, each of the lens groups G1 to G5 moves in the optical axis direction. At this time, the aperture stop S moves in the optical axis direction together with the third lens group G3.
In the zoom optical system according to the present embodiment, the entire second lens group G2 is moved along the optical axis, thereby focusing from an infinite object point to a short-distance object point. Specifically, when focusing from an object point at infinity to a near object point of 0.45 mm, the entire second lens group G2 is 1.8 mm at the wide-angle end state and 6 at the telephoto end state from the image side to the object side. Move 2 mm.
In the variable magnification optical system according to the present example, the cemented lens of the positive meniscus lens L41 and the negative lens L42 in the fourth lens group G4 is moved as a vibration-proof lens group so as to include a direction orthogonal to the optical axis. Perform image blur correction (anti-vibration).
The lens groups G1 to G5 having the above-described configuration and an adjustment mechanism described later are housed in a cam barrel 30 of a lens barrel as shown in FIG.

Next, an adjustment mechanism for adjusting the position of a predetermined lens in the variable magnification optical system according to the present embodiment will be described.
As shown in FIG. 2, the first, second, fourth, and fifth lens groups G1, G2, G4, and G5 are cylindrical first, second, fourth, and fifth holding members 11, 12, and 14, respectively. , 15 are held respectively. The positive lens L31 of the third lens group G3 is held by the cylindrical third holding member 13. The lenses L32 to L34 other than the positive lens L31 in the third lens group G3 are held by a sixth holding member (not shown) having the same configuration as the first holding member 11 and the like.
The first to fifth holding members 11 to 15 and the sixth holding member are fixed to cylindrical first to fifth sliding members 21 to 25 and a sixth sliding member (not shown), respectively.
The first to fifth sliding members 21 to 25 and the sixth sliding member are held by a cylindrical cam cylinder 30 via a cam mechanism (not shown), and the cam cylinder is rotated as the cam cylinder 30 rotates. 30 is configured to move in the optical axis direction. With this configuration, the lens groups G1 to G5 can be moved in the optical axis direction to perform zooming from the wide-angle end state to the telephoto end state.

The adjustment mechanism of the variable magnification optical system according to the present embodiment includes a first adjustment mechanism that adjusts the position of the positive lens L31 in the third lens group G3 and a second adjustment mechanism that adjusts the position of the entire fifth lens group G5. It consists of.
The first adjustment mechanism includes a third holding member 13, a third sliding member 23, and three screws 31 for fixing them.
As shown in FIG. 2A, an outer peripheral surface of the third holding member 13 is provided with an edge 13 a extending in the outer peripheral direction over the entire periphery. An inner groove 23 a is formed over the entire inner circumferential surface of the third sliding member 23, and the edge 13 a of the third holding member 13 is inserted into the inner groove 23 a. 2B, since the inner diameter of the inner groove 23a of the third sliding member 23 is larger than the outer diameter of the edge 13a of the third holding member 13, the third holding member 13 is moved to the third sliding member. The moving member 23 can be moved in a direction perpendicular to the optical axis within the inner groove 23a. The third sliding member 23 is formed with three screw holes 23b penetrating from the outer peripheral surface side toward the center to the bottom of the inner groove 23a at equal intervals along the circumferential direction.
Under such a configuration, the three screws 31 are screwed into the screw holes 23b of the third sliding member 23 to enter the inner grooves 23a, and the shaft portions of the screws 31 are connected to the edge portions 13a of the third holding member 13. By pressing, the third holding member 13 can be fixed to the third sliding member 23.

With the above configuration, the third sliding member 23 is adjusted by adjusting the amount of the shaft portion of each screw 31 entering the inner groove 23a of the third sliding member 23 by tightening or loosening the three screws 31 respectively. The position in the direction perpendicular to the optical axis of the third holding member 13 can be adjusted and fixed. That is, the positive lens L31 in the third lens group G3 can be shifted and decentered in the direction perpendicular to the optical axis, and the position can be adjusted, and the positive lens L31 can be arranged at a position for correcting the decentration error. . Thereby, it is possible to satisfactorily correct the deterioration of the imaging performance due to the decentration error, particularly the decentration coma in the telephoto end state.
As shown in FIG. 2A, the cam barrel 30 of the lens barrel has three openings 30a formed at positions facing the three screws 31 in the first adjustment mechanism. Each screw 31 can be exposed. Accordingly, it is possible to adjust the position of the positive lens L31 in the third lens group G3 described above without disassembling even after the zooming optical system according to the present embodiment is assembled at the time of manufacture.

The second adjustment mechanism includes a fifth holding member 15, a fifth sliding member 25, and three screws 32 for fixing them.
As shown in FIG. 2A and FIG. 2C, the outer peripheral surface of the fifth holding member 15 is provided with an edge portion 15a extending in the outer peripheral direction over the entire periphery. Three through-holes 15b penetrating in a direction parallel to the optical axis are formed at equal intervals along the circumferential direction. The inner diameter of the through hole 15b is larger than the outer diameter of the shaft portion of the screw 32.
On the inner peripheral surface of the fifth sliding member 25, an edge portion 25a extending in the inner peripheral direction is provided over the entire periphery, and three screw holes extending in a direction parallel to the optical axis are formed in the edge portion 25a. (Not shown) is formed so as to face the through hole 15b of the edge 15a of the fifth holding member 15.
Under such a configuration, the fifth holding member 15 is screwed into the screw holes of the edge 25a of the fifth sliding member 25 through the three screws 32 through the through holes 15b of the edge 15a of the fifth holding member 15, respectively. It can be fixed to the fifth sliding member 25. As described above, since the inner diameter of the through hole 15b of the edge 15a of the fifth holding member 15 is larger than the outer diameter of the shaft portion of the screw 32, the fifth holding member 15 is moved in a state where each screw 32 is loosened. It can be moved in a direction perpendicular to the optical axis.

With the above configuration, after loosening the three screws 32 and adjusting the position of the fifth holding member 15 in the direction perpendicular to the optical axis with respect to the fifth sliding member 25, each screw 32 is tightened to fix the position. be able to. That is, it is possible to adjust the position by shifting the entire fifth lens group G5 in the direction orthogonal to the optical axis, and it is possible to arrange the entire fifth lens group G5 at a position for correcting the eccentric error. As a result, it is possible to satisfactorily correct image quality deterioration due to an eccentric error, particularly image plane asymmetry in the telephoto end state.
As shown in FIG. 2A, the second adjustment mechanism having the above-described configuration is located closest to the image side in the cam barrel 30, and the three screws 32 are located on the image side with respect to the fifth holding member 15. Screwed. Therefore, each screw 32 is always exposed toward the image side in the cam cylinder 30. Therefore, even after the variable magnification optical system according to the present embodiment is assembled at the time of manufacture, the above-described position adjustment of the fifth lens group G5 can be performed without disassembly.

  A part of the fourth holding member 14 is moved in the fourth sliding member 24 so as to include a component in a direction orthogonal to the optical axis by a voice coil motor mechanism (not shown) or the like when camera shake occurs. It is configured. Accordingly, the cemented lens in the fourth lens group G4 can be moved as a vibration-proof lens group so as to include a component in a direction orthogonal to the optical axis, and image blur caused by camera shake can be corrected well.

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.
In [Surface data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, nd is the refractive index with respect to the d-line (wavelength λ = 587.6 nm), νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). Further, the object plane indicates the object plane, the variable indicates the variable plane spacing, the stop S indicates the aperture stop S, and the image plane indicates the image plane I. The radius of curvature r = ∞ indicates a plane, and the description of the refractive index nd of air = 1.000 is omitted. When the lens surface is an aspheric surface, the surface number is marked with * and the paraxial radius of curvature is shown in the column of the radius of curvature r.

[Aspherical data] shows 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
Here, x is the distance (sag amount) along the optical axis direction from the tangent plane of each aspherical surface at a height h in the vertical direction from the optical axis, κ is the conic constant, and A4, A6, A8, and A10 are non- The spherical coefficient r is defined as the radius of curvature of the reference spherical surface (paraxial radius of curvature). “E−n” (n: integer) represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “1.234 × 10 ⁻⁵ ”.

In [various data], FNO is the F number, 2ω is the angle of view, Y is the image height, TL is the total length of the optical system, and di (i: integer) is the variable surface interval of the i-th surface. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.
Here, “mm” is generally used as a unit of the focal length f, the radius of curvature r, and other lengths listed in Table 1. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
It should be noted that the symbols in Table 1 described above are similarly used in the table of the second embodiment described later.

  Here, in a lens in which the focal length of the entire lens system is f and the image stabilization coefficient (ratio of the amount of image movement on the image plane I to the amount of movement of the image stabilization lens group during blur correction) is K, the angle θ In order to correct the rotational blur of the lens, the anti-vibration lens group may be moved in a direction orthogonal to the optical axis by (f · tan θ) / K. Therefore, the variable magnification optical system according to the present example has a vibration proof coefficient of 0.98 and a focal length of 24.60 (mm) in the wide-angle end state. The moving amount of the anti-vibration lens group is 0.28 (mm). In the telephoto end state, since the image stabilization coefficient is 1.47 and the focal length is 117.00 (mm), the amount of movement of the image stabilization lens group for correcting the rotation blur of 0.29 ° is 0. 40 (mm).

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
1 214.7722 2.0000 1.846660 23.77
2 87.5000 7.4635 1.593189 67.87
3 -1279.2497 0.1000
4 58.9352 5.2795 1.755000 52.29
5 147.0393 Variable * 6 244.7505 1.3500 1.834810 42.72
7 15.8707 7.5000
8 -34.1921 1.0000 1.834810 42.72
9 -306.6108 0.1000
10 64.5088 4.7500 1.846660 23.77
11 -28.6256 0.5082
12 -24.9541 1.0000 1.806100 40.94
* 13 -142.4696 Variable
14 53.3000 2.5581 1.755000 52.29
15 -319.1136 1.4000
16 (Aperture S) ∞ 0.5000
17 31.1069 2.0000 1.846660 23.77
18 17.5705 7.2500 1.487490 70.45
19 -90.7232 0.1000
20 40.8460 2.7000 1.593189 67.87
21 -3872.3835 Variable
22 -56.1850 3.3307 1.850260 32.35
23 -16.8047 1.0000 1.755000 52.29
24 69.3978 2.7459
25 -49.7769 1.0000 1.755000 52.29
26 -208.3941 Variable * 27 131.4027 5.5000 1.589130 61.18
28 -24.1216 0.1000
29 471.8066 6.6400 1.487490 70.45
30 -20.9950 1.2000 1.850260 32.35
31 -99.6677 BF
Image plane ∞

[Aspherical data]
6th surface κ = 1.0000
A4 = 9.85080E-06
A6 = -2.64620E-08
A8 = 4.20250E-11
A10 = -2.74520E-14

13th surface κ = 10.0000
A4 = -9.97690E-07
A6 = -1.34120E-08
A8 = -3.09280E-11
A10 = 1.00000E-14

27th surface κ = -30.0000
A4 = -1.12040E-05
A6 = 1.08940E-08
A8 = -4.34270E-11
A10 = 9.85800E-14

[Various data]
Scaling ratio 4.76
W M T
f 24.6 50.6 117.1
FNO 4.1 4.1 4.1
2ω 85.4 45.1 20.4
Y 21.6 21.6 21.6
TL 145.9 162.0 190.8
BF 38.4 49.7 65.7

d5 2.9 22.0 44.2
d13 24.8 10.8 1.2
d21 2.5 6.2 9.1
d26 8.2 4.2 1.4

[Lens group data]
Group start surface f
1 1 107.1
2 6 -18.1
3 14 25.3
4 22 -30.3
5 27 45.4

[Conditional expression values]
(1) (−f2) /f3=0.72
(2) f2 / f4 = 0.60
(3) f5 / (− f4) = 1.50
(4) x5 / (− f2) = 1.18
(5) x4 / x3 = 0.72
(6) nd3b = 1.76

FIGS. 3A and 3B are diagrams showing various aberrations at the time of focusing at infinity in the wide-angle end state of the variable magnification optical system according to the first example of the present application, and a rotation blur of 0.64 °, respectively. FIG. 6 is a meridional lateral aberration diagram when image blur correction is performed on the image.
FIG. 4 is a diagram of various aberrations during focusing at infinity in the intermediate focal length state of the variable magnification optical system according to the first example of the present application.
FIGS. 5A and 5B are diagrams showing various aberrations at the time of focusing on infinity in the telephoto end state of the zoom optical system according to the first example of the present application, and a rotational blur of 0.29 °, respectively. FIG. 6 is a meridional lateral aberration diagram when image blur correction is performed on the image.
6 (a), 6 (b), and 6 (c), respectively, when a decentering error occurs in the variable magnification optical system according to the first example of the present application, at the time of focusing at infinity in the telephoto end state. The meridional lateral aberration diagram when the positive lens L31 in the third lens group G3 is decentered by 0.03 mm by the first adjusting mechanism, and the entire fifth lens group G5 is decentered by 0.03 mm by the second adjusting mechanism. FIG. 6 is an astigmatism diagram when the entire fifth lens group G5 is shifted by −0.03 mm. Each shift decentering amount is positive when the positive lens L31 and the fifth lens group G5 in the third lens group G3 are shifted and decentered perpendicularly to the optical axis upward in FIG.

In each aberration diagram of FIGS. 3 to 6, FNO represents an F number, and Y represents an image height. The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma diagram shows the value of each image height. d represents a d-line (λ = 587.6 nm), and g represents a g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In the aberration diagrams of the second embodiment shown below, the same reference numerals as in this embodiment are used.
From FIG. 3 to FIG. 5, the variable magnification optical system according to the present example has excellent imaging performance by correcting various aberrations well from the wide-angle end state to the telephoto end state, and is also excellent at the time of image stabilization. It can be seen that the imaging performance is excellent. In addition, as shown in FIG. 6, even when a decentration error occurs in the variable magnification optical system according to the present embodiment, it is possible to satisfactorily correct the deterioration of the imaging performance, particularly the decentration coma aberration and the image plane asymmetry in the telephoto end state. Recognize.

(Second embodiment)
FIG. 7 is a cross-sectional view showing a lens configuration of a variable magnification optical system according to the second example of the present application.
First, the lens shape of the variable magnification optical system according to the present embodiment will be described.
As shown in FIG. 7, the variable magnification optical system according to this example includes, in order from the object side (not shown), a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, And an aperture stop S, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power. The aperture stop S is adjacent to the object side of the third lens group G3.

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 negative meniscus lens L22 having a concave surface directed toward the object side, a biconvex positive lens L23, and an object side. And a negative meniscus lens L24 having a concave surface. The negative meniscus lens L21 is an aspheric lens in which an aspheric surface is formed on the object side glass lens surface, and the negative meniscus lens L24 is an aspheric lens in which an aspheric surface is formed on the image side glass lens surface.
The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, a cemented lens of a negative meniscus lens L32 having a convex surface facing the object side, and a biconvex positive lens L33, and a biconvex lens. And a positive lens L34.
The fourth lens group G4 includes, in order from the object side, a cemented lens of a positive meniscus lens L41 having a concave surface facing the object side and a biconcave negative lens L42, and a negative meniscus lens L43 having a concave surface facing the object side. Become.
The fifth lens group G5 includes, in order from the object side, a biconvex positive lens L51, a cemented lens of a biconvex positive lens L52, and a negative meniscus lens L53 having a concave surface facing the object. The positive lens L51 is an aspheric lens in which an aspheric surface is formed on the object side glass lens surface.

In the zoom optical system according to the present embodiment, when zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the second lens group G2 The air gap between the third lens group G3 decreases, the air gap between the third lens group G3 and the fourth lens group G4 increases, and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. In addition, each of the lens groups G1 to G5 moves in the optical axis direction. At this time, the aperture stop S moves in the optical axis direction together with the third lens group G3.
In the zoom optical system according to the present embodiment, the entire second lens group G2 is moved along the optical axis, thereby focusing from an infinite object point to a short-distance object point. Specifically, upon focusing from an infinite object point to a near object point of 0.45 mm, the entire second lens group G2 is 1.7 mm in the wide-angle end state and 5 in the telephoto end state from the image side to the object side. Move 6 mm.
In the variable magnification optical system according to the present example, the cemented lens of the positive meniscus lens L41 and the negative lens L42 in the fourth lens group G4 is moved as a vibration-proof lens group so as to include a direction orthogonal to the optical axis. Perform image blur correction (anti-vibration).

Next, an adjustment mechanism provided in the variable magnification optical system according to the present embodiment will be described.
The adjustment mechanism of the present embodiment is substantially the same as the adjustment mechanism of the first embodiment, and will be described with reference to FIG. 2 of the first embodiment.
In the present embodiment, the third holding member 13 holds the cemented lens of the negative meniscus lens L32 and the positive lens L33 in the third lens group G3. The other lenses L31 and L34 in the third lens group G3 are held by a sixth holding member (not shown). The adjustment mechanism of the present embodiment is different from the adjustment mechanism of the first embodiment only in this configuration.

  Therefore, according to the adjusting mechanism of the present embodiment, the first adjusting mechanism shifts and decenters the cemented lens in the third lens group G3 in the direction orthogonal to the optical axis, thereby performing image formation due to the decentering error. Degradation of performance, particularly decentration coma in the telephoto end state can be corrected well. Similarly to the first embodiment, the second adjustment mechanism shifts and decenters the entire fifth lens group G5 in the direction perpendicular to the optical axis, thereby adjusting the imaging performance due to decentering error, in particular. The image plane asymmetry in the telephoto end state can be corrected well. As in the first example, the cemented lens and the fifth lens group G5 in the third lens group G3 are not disassembled even after the variable magnification optical system according to the present example is assembled at the time of manufacture. The overall position can be adjusted.

Table 2 below provides values of specifications of the variable magnification optical system according to the present example.
Here, since the zoom optical system according to the present example has an image stabilization coefficient of 0.83 and a focal length of 24.60 (mm) in the wide-angle end state, it corrects a rotational shake of 0.64 °. The amount of movement of the image stabilizing lens group is 0.30 (mm). In the telephoto end state, since the image stabilization coefficient is 1.23 and the focal length is 117.00 (mm), the movement amount of the image stabilization lens group for correcting the rotation blur of 0.29 ° is 0. 45 (mm).

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞
1 246.0491 2.0000 1.846660 23.77
2 84.7836 7.7000 1.593189 67.87
3 -885.6521 0.1000
4 59.1074 5.4790 1.816000 46.63
5 140.2546 Variable * 6 824.4655 0.1000 1.553890 38.09
7 195.0000 1.5000 1.816000 46.63
8 15.9678 8.0000
9 -34.9410 1.0000 1.834810 42.72
10 -201.2418 0.1000
11 54.8341 4.5000 1.846660 23.77
12 -33.9457 0.5374
13 -29.1034 1.2000 1.806100 40.94
* 14 -537.4230 Variable
15 (Aperture S) ∞ 1.5000
16 55.6400 3.0000 1.755000 52.29
17 -194.6988 0.1000
18 29.1963 2.2576 1.846660 23.77
19 16.8888 6.8000 1.487490 70.45
20 -196.1439 0.5000
21 49.6966 3.0000 1.593189 67.87
22 -205.9500 Variable
23 -62.4232 3.3000 1.850260 32.35
24 -17.7266 1.0000 1.755000 52.29
25 85.0141 2.4116
26 -40.4411 1.0000 1.696800 55.52
27 -241.7912 Variable * 28 115.7889 6.4000 1.589130 61.18
29 -22.7957 0.1000
30 -433.8211 6.5000 1.487490 70.45
31 -19.6120 1.3500 1.850 260 32.35
32 -85.0846 BF
Image plane ∞

[Aspherical data]
6th surface κ = 1.0000
A4 = 1.59500E-05
A6 = -3.85270E-08
A8 = 5.99450E-11
A10 = -5.06110E-14

14th surface κ = 1.0000
A4 = 6.16800E-07
A6 = -1.55190E-08
A8 = -1.73480E-11
A10 = 0.00000E + 00

28th surface κ = -30.0000
A4 = -1.26410E-05
A6 = -2.71420E-10
A8 = 6.17710E-11
A10 = -2.07970E-13

[Various data]
Scaling ratio 4.53
W M T
f 24.7 49.0 111.8
FNO 4.1 4.1 4.1
2ω 85.4 45.1 20.4
Y 21.6 21.6 21.6
TL 147.6 162.2 190.9
BF 34.7 46.1 59.2

d5 3.1 20.1 44.7
d14 24.0 10.2 1.2
d22 4.0 8.2 11.1
d27 10.3 6.1 3.3

[Lens group data]
Group start surface f
1 1 107.2
2 6 -17.8
3 16 25.3
4 23 -30.7
5 28 45.5

[Conditional expression values]
(1) (−f2) /f3=0.70
(2) f2 / f4 = 0.58
(3) f5 / (− f4) = 1.48
(4) x5 / (− f2) = 1.38
(5) x4 / x3 = 0.71
(6) nd3b = 1.76

FIGS. 8A and 8B are diagrams showing various aberrations at the time of focusing at infinity in the wide-angle end state of the variable magnification optical system according to the second example of the present application, and a rotation blur of 0.64 °, respectively. FIG. 6 is a meridional lateral aberration diagram when image blur correction is performed on the image.
FIG. 9 is a diagram of various aberrations during focusing at infinity in the intermediate focal length state of the variable magnification optical system according to the second example of the present application.
FIGS. 10A and 10B are diagrams showing various aberrations at the time of focusing on infinity in the telephoto end state of the zoom optical system according to the second example of the present application, and a rotational blur of 0.29 °, respectively. FIG. 6 is a meridional lateral aberration diagram when image blur correction is performed on the image.
11 (a), 11 (b), and 11 (c), respectively, when a decentering error occurs in the variable magnification optical system according to the second example of the present application, at the time of focusing at infinity in the telephoto end state. The meridional lateral aberration diagram when the cemented lens of the negative meniscus lens L32 and the positive lens L33 in the third lens group G3 is shifted by 0.03 mm by the first adjustment mechanism, and the fifth lens group G5 by the second adjustment mechanism. FIG. 5 is an astigmatism diagram when the entire lens is shifted by 0.03 mm, and an astigmatism graph when the fifth lens group G5 is shifted by -0.03 mm. Each shift decentering amount is positive when the cemented lens in the third lens group G3 and the entire fifth lens group G5 are shifted decentered vertically to the optical axis in the plane of FIG.

  8 to 10, the variable magnification optical system according to the present example has excellent imaging performance with excellent correction of various aberrations from the wide-angle end state to the telephoto end state, and is also excellent during image stabilization. It can be seen that the imaging performance is excellent. In addition, as shown in FIG. 11, even when a decentration error occurs in the variable magnification optical system according to the present embodiment, it is possible to satisfactorily correct the deterioration of the imaging performance, particularly the decentration coma aberration and the image plane asymmetry in the telephoto end state. Recognize.

As described above, according to each of the above embodiments, a variable magnification optical system having good 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.
Although a five-group configuration is shown as a numerical example of the variable magnification optical system of the present application, the present application is not limited to this, and a variable magnification optical system of another group configuration (for example, six groups) can also be configured. . Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image 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.

Further, the variable magnification optical system of the present application includes a part of a lens group, an entire lens group, or a plurality of lens groups for focusing from an infinite object point to a short-distance object point. It is good also as a structure moved to an optical axis direction. In particular, it is preferable that at least a part of the second lens group is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor.
In the zoom optical system of the present application, either the entire lens group or a part thereof is moved as an anti-vibration lens group so as to include a component perpendicular to the optical axis, or rotated in an in-plane direction including the optical axis. It can also be configured to correct image blur caused by camera shake by moving (swinging). In particular, in the variable magnification optical system of the present application, it is preferable that at least a part of the fourth lens group is 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.

Further, an antireflection film having a high transmittance in a wide wavelength range may be applied to the lens surface of the lens constituting the variable magnification optical system of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.
Further, the zoom optical system of the present application has a zoom ratio of about 3 to 10 times.

Next, a camera equipped with the variable magnification optical system of the present application will be described with reference to FIG.
FIG. 12 is a diagram illustrating a configuration of a camera including the variable magnification optical system of the present application.
This camera 1 is a digital single-lens reflex camera provided with a variable magnification optical system according to the first embodiment as a photographing lens 2 as shown in FIG.
In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and imaged on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. Thereby, the light from the subject is picked up by the image pickup device 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.
With the above configuration, the present camera 1 in which the variable magnification optical system according to the first embodiment is mounted as the photographing lens 2 can achieve good optical performance. Even if a camera equipped with the variable magnification optical system according to the second embodiment as the taking lens 2 is configured, the same effect as the camera 1 can be obtained.

The outline of the manufacturing method of the variable magnification optical system of the present application will be described below with reference to FIG.
FIG. 13 is a diagram showing a manufacturing method of the variable magnification optical system of the present application.
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 that includes a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, and includes the following steps S1 to S3.
Step S1: Each lens group is prepared so that the second lens group, the third lens group, and the fourth lens group satisfy the following conditional expressions (1) and (2). Deploy.
(1) 0.65 <(− f2) / f3 <0.90
(2) 0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth lens group

Step S2: By providing a known moving mechanism in the lens barrel, the distance between the first lens group and the second lens group changes upon zooming from the wide-angle end state to the telephoto end state, and the second lens The distance between the third lens group and the third lens group is changed, the distance between the third lens group and the fourth lens group is changed, and the distance between the fourth lens group and the fifth lens group is changed.
Step S3: A known moving mechanism is provided in the lens barrel so that the fifth lens group can be shifted and decentered so as to include a direction orthogonal to the optical axis to adjust the position.
According to the method for manufacturing a variable magnification optical system of the present application, it is possible to manufacture a variable magnification optical system having good optical performance.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group I Image surface S Aperture stop

Claims (14)

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 negative refractive power A group and a fifth lens group having a positive refractive power,
Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, The distance between the third lens group and the fourth lens group changes, the distance between the fourth lens group and the fifth lens group changes,
The fifth lens group is configured to be shift decentered so as to include a direction orthogonal to the optical axis and to adjust the position.
A zoom optical system characterized by satisfying the following conditional expression:
0.65 <(− f2) / f3 <0.90
0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth lens group   2. The variable magnification optical system according to claim 1, wherein a position adjustment is possible by performing shift decentering so that at least a part of the third lens group includes a direction orthogonal to the optical axis. . The zoom lens system according to claim 1 or 2, wherein the following conditional expression is satisfied.
1.20 <f5 / (− f4) <2.00
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group   4. The image blur correction is performed by moving at least a part of the fourth lens group so as to include a direction orthogonal to the optical axis. 5. Variable magnification optical system.   The variable power optical system according to any one of claims 1 to 4, wherein the fourth lens group includes a cemented lens. The zoom lens system according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
0.70 <x5 / (− f2) <2.10
However,
f2: Focal length of the second lens group x5: Amount of movement of the fifth lens group on the optical axis 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 6, wherein the first lens unit moves from the image side to the object side during zooming from the wide-angle end state to the telephoto end state. system.   8. The zoom optical system according to claim 1, wherein the fifth lens unit moves from the image side to the object side during zooming from the wide-angle end state to the telephoto end state. 9. system.   The focusing from an object point at infinity to an object point at a short distance is performed by moving at least a part of the second lens group along the optical axis. The zoom optical system according to one item.   The variable magnification optical system according to claim 1, wherein the second lens group includes an aspheric lens. The zoom lens system according to any one of claims 1 to 10, wherein the following conditional expression is satisfied.
0.65 <x4 / x3 <0.90
However,
x3: Amount of movement on the optical axis of the third lens group during zooming from the wide-angle end state to the telephoto end state x4: The amount of movement of the fourth lens group during zooming from the wide-angle end state to the telephoto end state Amount of movement on the optical axis The third lens group includes at least one positive lens component;
The zoom lens system according to any one of claims 1 to 11, wherein the following conditional expression is satisfied.
1.70 <nd3b <1.85
However,
nd3b: refractive index of the positive lens component having the highest refractive index among the positive lens components in the third lens group with respect to the d-line of the glass material   An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 12. 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 negative refractive power A variable magnification optical system having a group and a fifth lens group having a positive refractive power,
The second lens group, the third lens group, and the fourth lens group satisfy the following conditional expressions:
Upon zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, An interval between the third lens group and the fourth lens group is changed, and an interval between the fourth lens group and the fifth lens group is changed;
A method of manufacturing a variable magnification optical system, characterized in that the fifth lens group can be shifted and decentered so as to include a direction perpendicular to the optical axis to adjust the position.
0.65 <(− f2) / f3 <0.90
0.42 <f2 / f4 <0.90
However,
f2: focal length of the second lens group f3: focal length of the third lens group f4: focal length of the fourth lens group

Images