JP6269714B2 - Variable-magnification optical system, optical device, and variable-magnification optical system manufacturing method - Google Patents

Description

  The present invention relates to a variable power optical system, an optical apparatus, and a method for manufacturing a variable power optical system suitable for an interchangeable lens for a camera, a digital camera, a video camera, and the like.

  Conventionally, many variable-power optical systems used for interchangeable lenses for single-lens reflex cameras have been proposed in which the most object-side lens group has a positive refractive power (see, for example, Patent Document 1).

JP 2002-365547 A

However, there has been a problem that it is difficult to obtain sufficiently high optical performance when attempting to reduce the size of the conventional variable magnification optical system as described above while increasing the magnification.
Accordingly, the present invention has been made in view of the above problems, and provides a small variable power optical system, an optical device, and a method for manufacturing the variable power optical system that have high zoom ratio and high optical performance. Objective.

In order to solve the above problems, the present invention
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the fourth lens group moves, the distance between the first lens group and the second lens group, and the distance between the second lens group and the third lens group. An interval, an interval between the third lens group and the fourth lens group, and an interval between the fourth lens group and the fifth lens group respectively change;
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.066 <R5 / f5 <0.600
However,
f5: Focal length of the fifth lens group R5: Curvature radius of the lens surface having a concave shape on the object side in the fifth lens group and having the smallest absolute value of the curvature radius.
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.066 <R5 / f5 <0.600
However,
f5: Focal length of the fifth lens group R5: Curvature radius of the lens surface having a concave shape on the object side in the fifth lens group and having the smallest absolute value of the curvature radius.
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
0.52 <f5 / f4 ≦ 0.856
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group
The present invention also provides
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the first lens group moves monotonously toward the object side, the distance between the first lens group and the second lens group, the second lens group and the second lens group. 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, respectively.
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group
f5: focal length of the fifth lens group
The present invention also provides
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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
A variable magnification optical system characterized by satisfying the following conditional expression is provided.
3.275 ≦ (−f5) / f3 <8.20
0.40 <f5 / f4 <1.60
However,
f3: focal length of the third lens group
f4: focal length of the fourth lens group
f5: focal length of the fifth lens group

The present invention also provides
Provided is an optical device comprising the variable magnification optical system.
The present invention also provides
In the manufacturing method of the variable magnification optical system,
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 refractive power in order from the object side along the optical axis. And a fourth lens group having negative refractive power and a fifth lens group having negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the fourth lens group moves, the distance between the first lens group and the second lens group, and the distance between the second lens group and the third lens group. The interval, the interval between the third lens group and the fourth lens group, and the interval between the fourth lens group and the fifth lens group are changed, respectively.
A variable magnification optical system manufacturing method characterized by satisfying the following conditional expression is provided.
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group

  According to the present invention, it is possible to provide a small variable power optical system, an optical device, and a method for manufacturing the variable power optical system with high zoom ratio and high optical performance.

It is sectional drawing in the wide angle end state of a variable magnification optical system concerning the 1st example of this application, the 1st intermediate focal length state, the 2nd intermediate focal length state, and the telephoto end state. (A) and (b) are various aberration diagrams at the time of focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the first example of the present application, respectively. FIGS. 9A and 9B are graphs showing various aberrations when the object at infinity is focused in the second 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 sectional drawing in the wide-angle end state of a zooming optical system concerning the 2nd example of this application, the 1st intermediate focal length state, the 2nd intermediate focal length state, and the telephoto end state. (A) and (b) are various aberration diagrams when focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the second example of the present application, respectively. FIGS. 9A and 9B are graphs showing various aberrations when the object at infinity is in focus in the second 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 sectional drawing in the wide-angle end state, 1st intermediate | middle focal distance state, 2nd intermediate | middle focal distance state, and telephoto end state of the variable magnification optical system concerning 3rd Example of this application. (A) and (b) are various aberration diagrams at the time of focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the third example of the present application, respectively. FIGS. 9A and 9B are graphs showing various aberrations when the object at infinity is in focus in the second 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. 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.

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 power optical system of the present application includes, in order from the object side along the optical axis, 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. A lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a negative refractive power, and at the time of zooming from the wide-angle end state to the telephoto end state, The distance between the second 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 fourth lens group and the fifth lens. The distance between the groups changes.

With the above-described configuration, the variable magnification optical system of the present application can perform variable magnification, and can suppress variations in distortion due to variable magnification.
In the variable power optical system of the present application, the fifth lens group is a negative lens group as described above, whereby the principal point position of the variable power optical system is arranged on the object side, and from the wide-angle end state to the telephoto end state. The overall length of the variable magnification optical system can be shortened in the entire variable magnification region. In addition to this, the distance from the optical axis of the peripheral luminous flux can be kept small, and the diameter of the fifth lens group can be reduced. If the fifth lens group is a positive lens group, when considering that the total length of the variable magnification optical system and the diameter of the fifth lens group are the same, each lens is compared with the case where the fifth lens group is a negative lens group. The refractive power of the group will increase. For this reason, it becomes difficult to suppress fluctuations in spherical aberration and astigmatism during zooming from the wide-angle end state to the telephoto end state.
From the above, it is possible to realize a small variable magnification optical system having high magnification and high optical performance.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (1).
(1) 1.80 <(− f5) / fw
However,
f5: focal length of the fifth lens group fw: focal length of the variable magnification optical system in the wide-angle end state

Conditional expression (1) defines the optimum focal length range of the fifth lens group, and is a conditional expression for suppressing aberration fluctuations accompanying zooming while ensuring a zoom ratio. By satisfying conditional expression (1), the variable magnification optical system of the present application can suppress variations in distortion and astigmatism due to variable magnification and achieve high optical performance.
If the corresponding value of conditional expression (1) of the variable magnification optical system of the present application is less than the lower limit value, the focal length of the fifth lens group becomes too small. For this reason, it becomes difficult to suppress fluctuations in distortion and astigmatism caused by zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (1) to 2.40.
Here, more preferably, the upper limit of conditional expression (1) is preferably 10.0. Since the corresponding value of the conditional expression (1) of the variable magnification optical system of the present application is less than the upper limit value, the fifth lens group can suppress the variation of distortion and astigmatism due to the variable magnification. Optical performance can be realized. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (1) to 8.50.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (2).
(2) 0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group

Conditional expression (2) defines the optimum focal length ratio of the fourth lens group and the fifth lens group, and is a conditional expression for suppressing aberration fluctuations accompanying zooming. By satisfying conditional expression (2), the variable magnification optical system of the present application can suppress variations in distortion and astigmatism due to variable magnification, and can realize high optical performance.
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, the focal length of the fifth lens group becomes too small with respect to the focal length of the fourth lens group. For this reason, it becomes difficult to suppress fluctuations in distortion and astigmatism caused by zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (2) to 0.52. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.66.
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 focal length of the fourth lens group becomes relatively small. For this reason, it becomes difficult to suppress the fluctuation of astigmatism generated in the fourth lens group, and high optical performance cannot be realized. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (2) to 2.80. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.60.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (3).
(3) 0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group

Conditional expression (3) defines the optimum focal length ratio of the third lens group and the fifth lens group, and is a conditional expression for suppressing aberration fluctuations accompanying zooming. By satisfying conditional expression (3), the variable magnification optical system of the present application suppresses each variation of distortion, astigmatism, spherical aberration, and coma due to variable magnification, and realizes high optical performance. Can do.
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 focal length of the fifth lens group becomes too small with respect to the focal length of the third lens group. For this reason, it becomes difficult to suppress fluctuations in distortion and astigmatism caused by zooming, and high optical performance cannot be realized. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (3) to 1.20. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 1.46.
On the other hand, when the corresponding value of conditional expression (3) of the variable magnification optical system of the present application exceeds the upper limit value, the focal length of the third lens group becomes relatively small. For this reason, it becomes difficult to suppress variations in spherical aberration and coma that occur in the third lens group, making it impossible to achieve high optical performance. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (3) to 7.50. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 5.80.

Moreover, it is desirable that the variable magnification optical system of the present application satisfies the following conditional expression (4).
(4) 0.066 <R5 / f5 <0.600
However,
f5: focal length of the fifth lens group R5: radius of curvature of the lens surface that is concave on the object side in the fifth lens group and has the smallest absolute value of curvature radius

Conditional expression (4) is a conditional expression for suppressing aberration fluctuations in the variable magnification optical system of the present application. In addition, R5 in the conditional expression (4) has a negative sign of the radius of curvature of the concave lens surface on the object side. By satisfying conditional expression (4), the variable magnification optical system of the present application can suppress astigmatism variation and coma variation due to magnification variation, and realize high optical performance.
If the corresponding value of conditional expression (4) of the variable magnification optical system of the present application is less than the lower limit value, it becomes difficult to suppress fluctuations in astigmatism due to variable magnification, and high optical performance cannot be realized. End up. In order to secure the effect of the present application, it is preferable to set the lower limit of conditional expression (4) to 0.087. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 0.098.
On the other hand, when the corresponding value of the conditional expression (4) of the variable magnification optical system of the present application exceeds the upper limit value, fluctuations in coma and astigmatism generated in the fourth lens group from the third lens group are changed to the fifth lens. It becomes difficult to suppress with a group, and high optical performance cannot be realized. In order to secure the effect of the present application, it is preferable to set the upper limit of conditional expression (4) to 0.490. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (4) to 0.350.

In the variable magnification optical system of the present application, the fifth lens group has a cemented lens, and the lens surface having a concave shape on the object side in the fifth lens group and having the smallest absolute value of the curvature radius is the cemented lens. It is desirable that the bonding surface is. With this configuration, the variable magnification optical system of the present application can suppress decentration coma generated by a manufacturing error of the lens surface and realize high optical performance.
In the variable power optical system of the present application, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state at the time of zooming from the wide-angle end state to the telephoto end state. It is desirable to decrease from the intermediate focal length state to the telephoto end state. With this configuration, the variable magnification optical system of the present application can suppress fluctuations in astigmatism generated from the third lens group to the fourth lens group at the time of zooming from the wide-angle end state to the telephoto end state. Performance can be realized.
In the variable power optical system of the present application, the distance between the fourth lens group and the fifth lens group is reduced from the wide-angle end state to the intermediate focal length state at the time of zooming from the wide-angle end state to the telephoto end state. It is desirable to increase from the intermediate focal length state to the telephoto end state. With this configuration, the variable magnification optical system of the present application can suppress fluctuations in astigmatism generated from the fourth lens group to the fifth lens group at the time of zooming from the wide-angle end state to the telephoto end state. Performance can be realized.

In the zoom optical system according to the present application, it is desirable that the third lens group and the fifth lens group move together when zooming from the wide-angle end state to the telephoto end state. With this configuration, the variable magnification optical system of the present application can structurally simplify the third lens group and the fifth lens group, and can suppress mutual decentration. For this reason, decentration coma and astigmatism generated due to manufacturing errors can be suppressed, and high optical performance can be realized.
In the variable power optical system of the present application, the distance between the first lens group and the second lens group is increased at the time of zooming from the wide-angle end state to the telephoto end state, and the second lens group and the third lens are increased. It is desirable to reduce the distance between groups. With this configuration, the variable magnification optical system of the present application suppresses spherical aberration and astigmatism that occur in each lens group, and changes in spherical aberration and astigmatism during zooming from the wide-angle end state to the telephoto end state. Can be suppressed.
In the variable magnification optical system of the present application, it is desirable that the fifth lens group has an aspherical surface. With this configuration, the variable magnification optical system of the present application can suppress coma and astigmatism generated in the fifth lens group, and can realize high optical performance.
In the variable magnification optical system of the present application, it is desirable that the aspheric surface is provided on the lens surface closest to the object in the fifth lens group. With this configuration, the variable magnification optical system of the present application can efficiently suppress coma and astigmatism generated in the fifth lens group, and can realize high optical performance.

The variable magnification optical system of the present application preferably has an aperture stop in or near the third lens group. With this configuration, the variable magnification optical system of the present application can suppress fluctuations in off-axis aberrations, particularly astigmatism, during zooming from the wide-angle end state to the telephoto end state.
In the zoom optical system of the present application, it is desirable that the aperture stop moves integrally with the third lens group when zooming from the wide-angle end state to the telephoto end state. With this configuration, the variable magnification optical system of the present application can suppress fluctuations in off-axis aberrations, particularly astigmatism, during zooming from the wide-angle end state to the telephoto end state.
The optical apparatus according to the present application includes the variable magnification optical system having the above-described configuration. Thereby, it is possible to realize a small optical device with high zoom ratio and high optical performance.

  The variable magnification optical system manufacturing method of the present application is a variable magnification optical system manufacturing method, in order from the object side along the optical axis, a first lens group having positive refractive power, and a second lens having negative refractive power. A lens group, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a negative refractive power. At the time of zooming to the 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, and the distance between the third lens group and the fourth lens group The distance and the distance between the fourth lens group and the fifth lens group are changed. As a result, it is possible to manufacture a small variable magnification optical system having high optical performance and high optical performance.

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 cross-sectional view of the zoom optical system according to the first example of the present application in the wide-angle end state, the first intermediate focal length state, the second intermediate focal length state, and the telephoto end state. In FIG. 1, W is a wide-angle end state, M1 is a first intermediate focal length state, M2 is a second intermediate focal length state, and T is a telephoto end state. Is the same.
The variable magnification optical system according to the present example includes, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refraction. The third lens group G3 having power, the fourth lens group G4 having negative refractive power, and the fifth lens group G5 having negative refractive power.
The first lens group G1 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, and a convex surface facing the object side. And a positive meniscus lens L13 facing the lens.

The second lens group G2 includes, in order from the object side along the optical axis, 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, and a biconvex positive lens L23. And a negative meniscus lens L24 having a concave surface facing the object side. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the image side.
The third lens group G3 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32, and a positive lens having a convex surface facing the object side. It is composed of a meniscus lens L33, a cemented lens of a biconvex positive lens L34 and a negative meniscus lens L35 having a concave surface facing the object side. An aperture stop S is provided near the object side of the third lens group G3.

The fourth lens group G4 includes, in order from the object side along the optical axis, only a cemented lens of a biconcave negative lens L41 and a biconvex positive lens L42. The negative lens L41 located closest to the object side in the fourth lens group G4 is a glass mold aspheric lens having an aspheric lens surface on the object side.
The fifth lens group G5 includes, in order from the object side along the optical axis, only a cemented lens including a biconvex positive lens L51 and a negative meniscus lens L52 having a concave surface directed toward the object side. The lens surface that is concave on the object side and has the smallest absolute value of the radius of curvature in the fifth lens group G5 is a cemented surface between the positive lens L51 and the negative meniscus lens L52. The positive lens L51 located closest to the object side in the fifth lens group G5 is a glass mold aspheric lens having an aspheric lens surface on the object side.

  With the above configuration, in the zoom optical system according to the present embodiment, the first lens group G1 monotonously moves toward the object side during zooming from the wide-angle end state W to the telephoto end state T, and the second lens group. G2 moves toward the image side from the wide-angle end state W to the first intermediate focal length state M1 and moves toward the object side from the first intermediate focal length state M1 to the telephoto end state T. The third lens group G3 and the fourth lens group G4 , And the fifth lens group G5 monotonously moves toward the object side. At this time, the aperture stop S, the third lens group G3, and the fifth lens group G5 move together. Thereby, at the time of zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3. Decreases, the distance between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state W to the first intermediate focal length state M1, and decreases from the first intermediate focal length state M1 to the telephoto end state T. The distance between the fourth lens group G4 and the fifth lens group G5 decreases from the wide-angle end state W to the first intermediate focal length state M1 and increases from the first intermediate focal length state M1 to the telephoto end state T.

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). 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. In the column of the radius of curvature r, ∞ indicates a plane, and the refractive index of air of 1.00000 is omitted in the column of the refractive index nd. Further, the aspherical surface is marked with * as the surface number, 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, h is the height in the direction perpendicular to the optical axis, x is the distance (sag amount) along the optical axis direction at the height h from the tangent plane of the apex of the aspheric surface to the aspheric surface, and κ is the conic constant. , A4, A6, A8, A10 are aspherical coefficients, and r is the radius of curvature of the reference sphere (paraxial radius of curvature). “E−n” (n: integer) indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”.

In [various data], FNO is the F number, ω is the half field angle (unit is “°”), Y is the image height, TL is the total length of the variable magnification optical system (the first lens group G1 when focusing on an object at infinity) (Distance from the lens surface closest to the object side to the image plane I), di (i: integer) is a variable surface interval of the i-th surface, and φ is the aperture stop diameter. W represents the wide-angle end state, M1 represents the first intermediate focal length state, M2 represents the second intermediate focal length state, and T represents the telephoto end state.
Here, “mm” is generally used as a unit of the focal length f, the radius of curvature r, and other lengths listed in Table 1. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
1 101.7859 1.4000 1.950000 29.37
2 32.5483 6.8500 1.497820 82.52
3 507.0890 0.1000
4 37.3347 4.8500 1.882997 40.76
5 300.9596 Variable

6 78.3556 1.0000 1.806100 40.74
* 7 8.1498 6.1500
8 -15.0638 1.0000 1.882997 40.76
9 -111.9446 0.1500
10 40.1532 3.6000 1.808090 22.79
11 -17.3545 0.6000
12 -13.7038 1.0000 1.902650 35.70
13 -22.0248 Variable

14 (Aperture S) ∞ 1.5000
15 29.5784 1.0000 2.000690 25.45
16 18.6363 2.8000 1.516800 64.10
17 -55.7763 2.0000
18 24.2391 2.1500 1.516800 64.10
19 858.3278 0.1000
20 17.6507 4.1000 1.497820 82.52
21 -15.2742 1.9000 1.950000 29.37
22 -23.3096 Variable

* 23 -14.7112 1.3500 1.806100 40.74
24 31.5094 2.3000 1.808090 22.79
25 -28.7594 Variable

* 26 32.3594 5.3000 1.516120 63.84
27 -5.7380 1.9000 1.902650 35.70
28 -44.3875 Bf
Image plane ∞

[Aspherical data]
7th surface κ 0.8091
A4 -2.81470E-05
A6 -5.35060E-07
A8 1.15520E-08
A10 -2.20190E-10

23rd surface κ -4.9782
A4 -5.87340E-05
A6 1.19560E-06
A8 -1.77790E-08
A10 9.84750E-11

26th surface κ 20.0000
A4 -8.22840E-05
A6 4.90020E-06
A8 -8.03990E-08
A10 6.79360E-09

[Various data]
Scaling ratio 9.42

W T
f 10.30 to 97.00
FNO 4.11 to 5.87
ω 39.54 to 4.59 °
Y 7.97-7.97
TL 100.65-133.98

W M1 M2 T
f 10.30000 35.00000 60.00000 97.00000
ω 39.58845 12.47589 7.34848 4.58728
FNO 4.10582 5.89080 5.89975 5.86696
φ 8.80 8.80 9.20 11.60
d5 1.80000 19.37763 32.00000 35.69237
d13 26.66538 7.08688 5.31318 2.20000
d22 2.21304 4.15113 3.20959 2.20000
d25 3.82473 1.88667 2.82824 3.83771
Bf 13.04939 24.70184 26.64686 36.95330

[Lens group data]
Group start surface f
1 1 63.72998
2 6 -11.45481
3 15 14.77721
4 23 -42.51000
5 26 -36.37957

[Conditional expression values]
(1) (−f5) /fw=−3.532
(2) f5 / f4 = 0.856
(3) (−f5) /f3=2.462
(4) R5 / f5 = 0.158

FIGS. 2A and 2B are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the first example of the present application, respectively. It is.
FIGS. 3A and 3B are graphs showing various aberrations when the object at infinity is in focus in the second 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 represents an F number, and A represents a light incident angle (unit: “degree”). d indicates an aberration at the d-line (wavelength λ = 587.6 nm), and g indicates an aberration at the g-line (wavelength λ = 435.8 nm). Note that the distortion diagrams without d and g show aberrations 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 each aberration diagram, it can be seen that the variable power optical system according to the present example has excellent optical performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state.

(Second embodiment)
FIG. 4 is a cross-sectional view of the zoom optical system according to the second example of the present application in the wide-angle end state, the first intermediate focal length state, the second intermediate focal length state, and the telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refraction. The third lens group G3 having power, the fourth lens group G4 having negative refractive power, and the fifth lens group G5 having negative refractive power.
The first lens group G1 includes, in order from the object side along the optical axis, 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 lens having a convex surface facing the object side. And a meniscus lens L13.

The second lens group G2 includes, in order from the object side along the optical axis, 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, and a biconvex positive lens L23. And a negative meniscus lens L24 having a concave surface facing the object side. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the image side.
The third lens group G3 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32, and a positive lens having a convex surface facing the object side. It is composed of a meniscus lens L33, a cemented lens of a biconvex positive lens L34 and a negative meniscus lens L35 having a concave surface facing the object side. An aperture stop S is provided near the object side of the third lens group G3.

The fourth lens group G4 includes, in order from the object side along the optical axis, only a cemented lens of a biconcave negative lens L41 and a biconvex positive lens L42. The negative lens L41 located closest to the object side in the fourth lens group G4 is a glass mold aspheric lens having an aspheric lens surface on the object side.
The fifth lens group G5 includes, in order from the object side along the optical axis, a positive meniscus lens L51 having a convex surface directed toward the object side, a positive lens L52 having a biconvex shape, and a negative meniscus lens L53 having a concave surface directed toward the object side. And a cemented lens. The lens surface that is concave on the object side and has the smallest absolute value of the radius of curvature in the fifth lens group G5 is a cemented surface between the positive lens L52 and the negative meniscus lens L53. The positive meniscus lens L51 located on the most object side in the fifth lens group G5 is a glass mold aspheric lens having an aspheric lens surface on the object side.

With the above configuration, in the zoom optical system according to the present embodiment, the first lens group G1 monotonously moves toward the object side during zooming from the wide-angle end state W to the telephoto end state T, and the second lens group. G2 moves toward the image side from the wide-angle end state W to the second intermediate focal length state M2 and moves toward the object side from the second intermediate focal length state M2 to the telephoto end state T. The third lens group G3 and the fourth lens group G4 , And the fifth lens group G5 monotonously moves toward the object side. At this time, the aperture stop S, the third lens group G3, and the fifth lens group G5 move together. Thereby, at the time of zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3. Decreases, the distance between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state W to the second intermediate focal length state M2, and decreases from the second intermediate focal length state M2 to the telephoto end state T. The distance between the fourth lens group G4 and the fifth lens group G5 decreases from the wide-angle end state W to the second intermediate focal length state M2 and increases from the second intermediate focal length state M2 to the telephoto end state T.
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 ∞
1 149.4765 1.4000 1.950000 29.37
2 38.6411 6.6000 1.497820 82.57
3 -351.6316 0.1000
4 41.7750 4.6000 1.883000 40.66
5 328.2384 Variable

6 72.4891 1.0000 1.806100 40.97
* 7 7.7391 5.8500
8 -13.9505 1.0000 1.883000 40.66
9 -103.9877 0.1000
10 40.8028 3.4000 1.808090 22.74
11 -18.8169 0.6000
12 -13.4665 1.0000 1.883000 40.66
13 -18.2363 Variable

14 (Aperture S) ∞ 1.4000
15 28.0065 1.5000 2.000690 25.46
16 17.4484 2.9000 1.497820 82.57
17 -29.2004 2.0000
18 28.1447 1.6000 1.795040 28.69
19 53.0274 0.1000
20 27.5255 4.2000 1.497820 82.57
21 -13.9702 2.1800 2.000690 25.46
22 -20.5898 Variable

* 23 -13.2794 1.0000 1.806100 40.97
24 24.2300 3.5000 1.728250 28.38
25 -18.1038 Variable

* 26 47.8180 1.6500 1.583130 59.42
27 100.8528 0.2000
28 38.0626 3.8000 1.516800 63.88
29 -8.1478 1.0000 1.954000 33.46
30 -52.2418 Bf
Image plane ∞

[Aspherical data]
7th surface κ 0.9456
A4 -7.24873E-05
A6 -1.38772E-06
A8 3.49795E-08
A10 -9.90184E-10

23rd surface κ -5.0310
A4 -2.13400E-04
A6 3.25281E-06
A8 -4.07563E-08
A10 2.36604E-10

26th surface κ -15.0179
A4 1.31767E-05
A6 1.09725E-06
A8 -1.09512E-08
A10 4.81750E-10

[Various data]
Scaling ratio 9.42

W T
f 10.30 to 97.00
FNO 4.13 to 5.79
ω 39.34 to 4.54 °
Y 7.97-7.97
TL 104.60-137.98

W M1 M2 T
f 10.30000 20.00000 50.00000 97.00000
ω 39.34094 21.01370 8.74331 4.54414
FNO 4.12898 4.96138 5.51068 5.79408
φ 9.00 9.00 9.50 9.80
d5 2.00000 11.66890 30.95696 41.68937
d13 26.10451 13.02302 4.99096 2.00000
d22 2.34607 4.05509 5.18708 2.50149
d25 7.92894 6.21994 5.08793 7.77351
Bf 13.54976 19.90197 26.27832 31.33645

[Lens group data]
Group start surface f
1 1 66.37666
2 6 -11.22172
3 15 16.67848
4 23 -58.03866
5 26 -77.03015

[Conditional expression values]
(1) (-f5) / fw = 7.479
(2) f5 / f4 = 1.327
(3) (−f5) /f3=4.619
(4) R5 / f5 = 0.106

FIGS. 5A and 5B are graphs showing various aberrations when focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the second example of the present application, respectively. It is.
FIGS. 6A and 6B are graphs showing various aberrations when focusing on an object at infinity in the second 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 each aberration diagram, it can be seen that the variable power optical system according to the present example has excellent optical performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state.

(Third embodiment)
FIG. 7 is a cross-sectional view of the zoom optical system according to the third example of the present application in the wide-angle end state, the first intermediate focal length state, the second intermediate focal length state, and the telephoto end state.
The variable magnification optical system according to the present example includes, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refraction. A third lens group G3 having power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power Has been.
The first lens group G1 includes, in order from the object side along the optical axis, 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 lens having a convex surface facing the object side. And a meniscus lens L13.

The second lens group G2 includes, in order from the object side along the optical axis, 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, and a biconvex positive lens L23. And a negative meniscus lens L24 having a concave surface facing the object side. The negative meniscus lens L21 is a glass mold aspheric lens having an aspheric lens surface on the image side.
The third lens group G3 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32, and a positive lens having a convex surface facing the object side. It is composed of a meniscus lens L33, a cemented lens of a biconvex positive lens L34 and a negative meniscus lens L35 having a concave surface facing the object side. An aperture stop S is provided between the positive lens L32 and the positive meniscus lens L33 in the third lens group G3.

The fourth lens group G4 includes, in order from the object side along the optical axis, only a cemented lens of a biconcave negative lens L41 and a biconvex positive lens L42. The negative lens L41 located closest to the object side in the fourth lens group G4 is a glass mold aspheric lens having an aspheric lens surface on the object side.
The fifth lens group G5 includes, in order from the object side along the optical axis, a negative meniscus lens L51 having a convex surface facing the object side, a positive lens L52 having a biconvex shape, and a negative meniscus lens L53 having a concave surface facing the object side. And a cemented lens. The lens surface that is concave on the object side and has the smallest absolute value of the radius of curvature in the fifth lens group G5 is a cemented surface between the positive lens L52 and the negative meniscus lens L53. Further, the negative meniscus lens L51 located closest to the object side in the fifth lens group G5 is a glass mold aspheric lens having an aspheric lens surface on the object side.
The sixth lens group G6 includes solely a positive meniscus lens L61 having a convex surface directed toward the object side.

With the above configuration, in the zoom optical system according to the present embodiment, the first lens group G1 monotonously moves toward the object side during zooming from the wide-angle end state W to the telephoto end state T, and the second lens group. G2 moves toward the image side from the wide-angle end state W to the first intermediate focal length state M1 and moves toward the object side from the first intermediate focal length state M1 to the telephoto end state T. The third lens group G3 and the fourth lens group G4 The fifth lens group G5 and the sixth lens group G6 move monotonously toward the object side. At this time, the aperture stop S, the third lens group G3, and the fifth lens group G5 move together. Thereby, at the time of zooming from the wide-angle end state W to the telephoto end state T, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3. Decreases, the distance between the third lens group G3 and the fourth lens group G4 increases from the wide-angle end state W to the second intermediate focal length state M2, and decreases from the second intermediate focal length state M2 to the telephoto end state T. The distance between the fourth lens group G4 and the fifth lens group G5 decreases from the wide-angle end state W to the second intermediate focal length state M2, increases from the second intermediate focal length state M2 to the telephoto end state T, and the fifth lens group The interval between G5 and the sixth lens group G6 increases.
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 ∞
1 154.5301 1.4000 1.950000 29.37
2 39.8607 7.2500 1.497820 82.57
3 -283.4227 0.1000
4 43.5964 4.8500 1.883000 40.66
5 446.9311 Variable

6 96.1250 1.0000 1.806100 40.97
* 7 8.1961 6.1500
8 -14.4871 1.0000 1.883000 40.66
9 -97.9643 0.1000
10 44.3150 3.6500 1.808090 22.74
11 -17.2518 0.8000
12 -14.4809 1.0000 1.883000 40.66
13 -24.0963 Variable

14 30.1004 1.4000 1.950000 29.37
15 18.1656 2.8500 1.497820 82.57
16 -30.1820 1.0000
17 (Aperture S) ∞ 1.0000
18 21.4294 1.5000 1.806100 40.97
19 61.8962 1.0500
20 32.7220 2.5500 1.497820 82.57
21 -17.3215 1.0000 2.000690 25.46
22 -26.1872 Variable

* 23 -11.1837 1.0000 1.806100 40.73
24 20.9851 3.4000 1.647690 33.72
25 -11.9280 Variable

* 26 31.4353 1.0000 1.806100 40.73
27 10.4731 1.0000
28 10.6935 5.2000 1.575010 41.51
29 -8.0000 1.0000 1.950000 29.37
30 -43.9250 Variable

31 78.8127 1.4000 1.808090 22.74
32 130.1997 Bf
Image plane ∞

[Aspherical data]
7th surface κ 1.0193
A4 -7.25972E-05
A6 -2.01927E-06
A8 5.23101E-08
A10 -1.09165E-09

23rd surface κ -3.3364
A4 -2.63114E-04
A6 2.76766E-06
A8 -3.39467E-08
A10 6.49727E-11

26th surface κ 1.5816
A4 -1.52827E-05
A6 7.21136E-07
A8 -2.56336E-09
A10 4.03092E-10

[Various data]
Scaling ratio 9.42

W T
f 10.30 to 97.00
FNO 3.63 to 5.80
ω 39.36 to 4.56 °
Y 7.97-7.97
TL 104.89-139.98

W M1 M2 T
f 10.30000 20.00000 50.00000 97.00000
ω 39.35588 21.00824 8.74248 4.55748
FNO 3.63391 4.50179 5.47868 5.80104
φ 10.60 10.60 10.60 10.60
d5 2.00000 12.01131 29.94199 40.54244
d13 26.77743 14.69932 6.72364 3.40000
d22 2.66702 3.74847 4.51403 2.66188
d25 4.74793 3.66651 2.90094 4.75306
d30 1.50000 1.80000 2.40000 4.50000
Bf 13.54939 20.44615 27.99896 30.47600

[Lens group data]
Group start surface f
1 1 64.96294
2 6 -10.79650
3 14 15.45800
4 23 -68.94014
5 26 -50.62258
6 31 244.13912

[Conditional expression values]
(1) (−f5) /fw=4.915
(2) f5 / f4 = 0.734
(3) (−f5) /f3=3.275
(4) R5 / f5 = 0.158

FIGS. 8A and 8B are graphs showing various aberrations when focusing on an object at infinity in the wide-angle end state and the first intermediate focal length state of the variable magnification optical system according to the third example of the present application, respectively. It is.
FIGS. 9A and 9B are graphs showing various aberrations when focusing on an object at infinity in the second 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 each aberration diagram, it can be seen that the variable power optical system according to the present example has excellent optical performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state.

According to each of the above-described embodiments, it is possible to realize a small variable magnification optical system having high magnification and high optical performance. 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.
As numerical examples of the variable magnification optical system of the present application, those having a five-group or six-group configuration are shown, but the present application is not limited to this, and constitutes a variable-magnification optical system having other group configurations (for example, seven groups). 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 fourth 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. By moving (swinging), it is also possible to correct the image blur caused by camera shake or the like. 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 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.

In the variable magnification optical system of the present application, the aperture stop is preferably disposed between the second lens group and the third lens group, or in the third lens group. It is good also as a structure which substitutes the role.
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 20 times.

Next, a camera provided with the variable magnification optical system of the present application will be described with reference to FIG.
FIG. 10 is a diagram illustrating a configuration of a camera including the variable magnification optical system of the present application.
The camera 1 is a digital single-lens reflex camera provided with the variable magnification optical system according to the first embodiment as the photographing lens 2.
In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and imaged on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. Thereby, the light from the subject is picked up by the image pickup device 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.
Here, the zoom optical system according to the first embodiment mounted as the photographing lens 2 on the camera 1 is small, high zoom, and has high optical performance as described above. As a result, the camera 1 can achieve high optical performance while achieving downsizing and high zooming. Even if a camera equipped with the variable magnification optical system according to the second and third examples as the photographing lens 2 is configured, the same effect as the camera 1 can be obtained. In addition, even when the zoom optical system according to each of the above embodiments is mounted on a camera having a configuration that does not include the quick return mirror 3, the same effects as those of the camera 1 can be obtained.

Finally, the outline of the manufacturing method of the variable magnification optical system of this application is demonstrated based on FIG.
The manufacturing method of the variable magnification optical system of the present application shown in FIG. 17 includes the following steps S1 and S2.
Step S1: In order from the object side along the optical axis, 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 A fourth lens group having a refractive power of 5 and a fifth lens group having a negative refractive power.
Step S2: By providing a known moving mechanism, the distance between the first lens group and the second lens group, the second 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 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.
According to the zoom lens manufacturing method of the present application, it is possible to manufacture a small variable magnification optical system having high variable power and high optical performance.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group S Aperture stop I Image surface W Wide-angle end state M1 1st intermediate focal length state M2 2nd Intermediate focal length state T Telephoto end state

Claims (27)

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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the fourth lens group moves, the distance between the first lens group and the second lens group, and the distance between the second lens group and the third lens group. An interval, an interval between the third lens group and the fourth lens group, and an interval between the fourth lens group and the fifth lens group respectively change;
A zoom optical system characterized by satisfying the following conditional expression:
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A zoom optical system characterized by satisfying the following conditional expression:
0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A zoom optical system characterized by satisfying the following conditional expression:
0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A zoom optical system characterized by satisfying the following conditional expression:
0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A zoom optical system characterized by satisfying the following conditional expression:
0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Decreased,
A zoom optical system characterized by satisfying the following conditional expression:
0.066 <R5 / f5 <0.600
However,
f5: focal length of the fifth lens group R5: radius of curvature of the lens surface that is concave on the object side in the fifth lens group and has the smallest absolute value of curvature radius 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. Increase,
A zoom optical system characterized by satisfying the following conditional expression:
0.066 <R5 / f5 <0.600
However,
f5: focal length of the fifth lens group R5: radius of curvature of the lens surface that is concave on the object side in the fifth lens group and has the smallest absolute value of curvature radius 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
A zoom optical system characterized by satisfying the following conditional expression:
0.52 <f5 / f4 ≦ 0.856
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the first lens group moves monotonously toward the object side, the distance between the first lens group and the second lens group, the second lens group and the second lens group. 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, respectively.
A zoom optical system characterized by satisfying the following conditional expression:
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group 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 refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
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 respectively change,
A zoom optical system characterized by satisfying the following conditional expression:
3.275 ≦ (−f5) / f3 <8.20
0.40 <f5 / f4 <1.60
However,
f3: focal length of the third lens group
f4: focal length of the fourth lens group f5: focal length of the fifth lens group The following claims to satisfying the expression characterized by 1, claim 7 claim 4, the variable-power optical system according to any one of claims 9.
0.40 <f5 / f4 <4.20
However,
f4: focal length of the fourth lens group f5: focal length of the fifth lens group The zoom lens system according to any one of claims 6 to 8, wherein the following conditional expression is satisfied.
0.88 <(− f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group The zoom lens system according to any one of claims 1 to 8 , wherein the following conditional expression is satisfied.
0.066 <R5 / f5 <0.600
However,
f5: focal length of the fifth lens group R5: radius of curvature of the lens surface that is concave on the object side in the fifth lens group and has the smallest absolute value of curvature radius The fifth lens group includes a cemented lens;
The smallest the lens surface of the absolute value of the curvature radius at concave on the object side in the fifth lens group, claim 6, characterized in that the cemented surface of the cemented lens, according to claim 7, claim 13 The zoom optical system according to any one of the above. During zooming from the wide-angle end state to the telephoto end state, the distance between the third lens group and the fourth lens group increases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. claim 1, characterized in that decreasing, claim 3, claim 5, the variable-power optical system according to any one of claims 10 claim 7. When zooming from the wide-angle end state to the telephoto end state, the distance between the fourth lens group and the fifth lens group decreases from the wide-angle end state to the intermediate focal length state, and from the intermediate focal length state to the telephoto end state. The variable power optical system according to any one of claims 1 to 8, wherein the optical system increases. 10. The zoom optical system according to claim 2, wherein the fourth lens unit moves during zooming from the wide-angle end state to the telephoto end state. 11. 9. The variable power optical system according to claim 2, wherein the first lens unit monotonously moves toward the object side during zooming from the wide-angle end state to the telephoto end state. . The variable magnification optical system according to any one of claims 1 to 18 , wherein the following conditional expression is satisfied.
1.80 <(− f5) / fw
However,
f5: focal length of the fifth lens group fw: focal length of the variable magnification optical system in the wide-angle end state The zoom lens according to any one of claims 1 to 19 , wherein the third lens unit and the fifth lens unit move together when zooming from the wide-angle end state to the telephoto end state. Double optical system. 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 increases and the distance between the second lens group and the third lens group decreases. variable-power optical system according to any one of claims 20 to claim 1, wherein. The variable magnification optical system according to any one of claims 1 to 21 , wherein the fifth lens group has an aspherical surface. 23. The variable magnification optical system according to claim 22 , wherein the aspheric surface is provided on a lens surface closest to the object side in the fifth lens group. The variable power optical system according to any one of claims 1 to 23 , further comprising an aperture stop in or near the third lens group. 25. The zoom optical system according to claim 24 , wherein the aperture stop moves integrally with the third lens group during zooming from the wide-angle end state to the telephoto end state. An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 25 . In the manufacturing method of the variable magnification optical system,
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 refractive power in order from the object side along the optical axis. And a fourth lens group having negative refractive power and a fifth lens group having negative refractive power,
At the time of zooming from the wide-angle end state to the telephoto end state, the fourth lens group moves, the distance between the first lens group and the second lens group, and the distance between the second lens group and the third lens group. The interval, the interval between the third lens group and the fourth lens group, and the interval between the fourth lens group and the fifth lens group are changed, respectively.
A variable magnification optical system manufacturing method characterized by satisfying the following conditional expression:
3.275 ≦ (−f5) / f3 <8.20
However,
f3: focal length of the third lens group f5: focal length of the fifth lens group

Images