JP2021033247A - Zoom optical system, optical device, and method of manufacturing zoom optical system - Google Patents

Abstract

To provide a zoom optical system which has a focusing lens group with sufficiently reduced weight and offers suppressed variation in aberrations, including spherical aberration, while shifting focus from an object at infinity to a nearby object.SOLUTION: A zoom optical system ZL provided herein comprises a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a succeeding lens group GR arranged on an optical axis in order from the object side, and is configured such that distances between adjacent lens groups change while zooming from the wide-angle end to the telephoto end. The succeeding lens group comprises a first focusing lens group G3 having positive refractive power and a second focusing lens group G5 having positive refractive power. The first and second focusing lens groups move along the optical axis while shifting focus from infinity to a short distance.SELECTED DRAWING: Figure 1

Description

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

Conventionally, variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras and the like have been proposed (see, for example, Patent Document 1). However, in the conventional variable magnification optical system, the weight reduction of the focusing lens group is insufficient, and fluctuations in various aberrations such as spherical aberration during focusing from an infinity object to a short-range object are caused. It was difficult to suppress.

JP-A-2015-28530

The variable magnification optical system according to the present invention includes a first lens group having a negative refractive force, a second lens group having a positive refractive force, and a succeeding lens arranged side by side on the optical axis in order from the object side. The lens group has a group, and when the magnification is changed from the wide-angle end to the telescopic end, the distance between the adjacent lens groups changes, and the subsequent lens group has a positive refraction with the first focusing lens group having a positive refractive force. It has a second focusing lens group having a force, and when focusing from infinity to a short distance, the first focusing lens group and the second focusing lens group move in the optical axis direction.

The optical device according to the present invention is configured to include the above-mentioned variable magnification optical system.

The method for manufacturing a variable magnification optical system according to the present invention includes a first lens group having a negative refractive force and a second lens group having a positive refractive force arranged side by side on the optical axis in order from the object side. A method for manufacturing a variable magnification optical system, which has a subsequent lens group, and the subsequent lens group has a first focusing lens group having a positive refractive power and a second focusing lens group having a positive refractive power. Therefore, when the magnification is changed from the wide-angle end to the telescopic end, the distance between the adjacent lens groups changes, and when focusing from infinity to a short distance, the first focusing lens group and the second focusing lens group Each lens is arranged in the lens barrel so that the lens moves in the optical axis direction.

It is a figure which shows the lens structure of the variable magnification optical system which concerns on 1st Example. 2 (A), 2 (B), and 2 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the first embodiment, respectively. It is a diagram of various aberrations of. 3 (A), 3 (B), and 3 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the first embodiment, respectively. It is a diagram of various aberrations of. It is a figure which shows the lens structure of the variable magnification optical system which concerns on 2nd Example. 5 (A), 5 (B), and 5 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the second embodiment, respectively. It is a diagram of various aberrations of. 6 (A), 6 (B), and 6 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the second embodiment, respectively. It is a diagram of various aberrations of. It is a figure which shows the lens structure of the variable magnification optical system which concerns on 3rd Example. 8 (A), 8 (B), and 8 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the third embodiment, respectively. It is a diagram of various aberrations of. 9 (A), 9 (B), and 9 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the third embodiment, respectively. It is a diagram of various aberrations of. It is a figure which shows the lens structure of the variable magnification optical system which concerns on 4th Example. 11 (A), 11 (B), and 11 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fourth embodiment, respectively. It is a diagram of various aberrations of. 12 (A), 12 (B), and 12 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fourth embodiment, respectively, at the time of short-distance focusing. It is a diagram of various aberrations of. It is a figure which shows the lens structure of the variable magnification optical system which concerns on 5th Example. 14 (A), 14 (B), and 14 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fifth embodiment, respectively. It is a diagram of various aberrations of. 15 (A), 15 (B), and 15 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fifth embodiment, respectively, at the time of short-distance focusing. It is a diagram of various aberrations of. It is a figure which shows the structure of the camera provided with the variable magnification optical system which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the variable magnification optical system which concerns on this Embodiment.

Hereinafter, preferred embodiments according to the present invention will be described. First, a camera (optical device) provided with a variable magnification optical system according to the present embodiment will be described with reference to FIG. As shown in FIG. 16, the camera 1 is composed of a main body 2 and a photographing lens 3 attached to the main body 2. The main body 2 includes an image sensor 4, a main body control unit (not shown) that controls the operation of a digital camera, and a liquid crystal operation screen 5. The photographing lens 3 includes an optical system ZL composed of a plurality of lens groups and a lens position control mechanism (not shown) for controlling the position of each lens group. The lens position control mechanism is composed of a sensor that detects the position of the lens group, a motor that moves the lens group back and forth along the optical axis, a control circuit that drives the motor, and the like.

The light from the subject is collected by the optical system ZL of the photographing lens 3 and reaches the image plane I of the image sensor 4. The light from the subject that has reached the image plane I is photoelectrically converted by the image sensor 4 and recorded as digital image data in a memory (not shown). The digital image data recorded in the memory can be displayed on the liquid crystal screen 5 according to the operation of the user. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror.

Next, the variable magnification optical system (photographing lens) according to the present embodiment will be described. As shown in FIG. 1, the variable magnification optical system ZL (1) as an example of the variable magnification optical system (zoom lens) ZL according to the present embodiment is arranged side by side on the optical axis in order from the object side, and is negative. It has a first lens group having a refractive power of, a second lens group having a positive refractive power, and a succeeding lens group GR, and the distance between the adjacent lens groups when the magnification is changed from the wide-angle end to the telescopic end. Changes. Subsequent lens group GR includes a first focusing lens group having a positive refractive power (for example, composed of a third lens group G3) and a second focusing lens group having a positive refractive power (for example, a fifth lens). The first focusing lens group and the second focusing lens group move in the optical axis direction when focusing from infinity to a short distance.

By configuring the first focusing lens group and the second focusing lens group to move in the optical axis direction when focusing from infinity to a short distance in this way, the focusing lens group does not become large. It is possible to satisfactorily correct the curvature of field that occurs during focusing from infinity to a short distance.

This variable magnification optical system preferably satisfies the following conditional expression (1).
0.10 <(−f1) /f2 <1.20 ・ ・ ・ (1)

The above conditional formula (1) defines the ratio of the focal lengths of the first lens group G1 and the second lens group G2 after defining the configuration of the succeeding lens group, but satisfies the conditional formula (1). By doing so, various aberrations such as spherical aberration at the time of scaling from the wide-angle end to the telephoto end can be satisfactorily corrected. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (1) is set to, for example, 1.15, 1.10, 1.05, 1.00, 0.95, 0.90. , 0.85, 0.80, 0.75, 0.73, and more preferably 0.70. Further, it is preferable to set the lower limit value of the conditional expression (1) to, for example, 0.15, 0.20, 0.23, 0.27, 0.30, 0.32, and further 0.35.

Further, the variable magnification optical system preferably satisfies the following conditional expression (2).
0.20 <ff1 / ff2 <1.70 ... (2)
However, ff1: focal length of the first focusing lens group ff2: focal length of the second focusing lens group

The above conditional expression (2) defines the ratio of the focal lengths of the two focusing lens groups. By satisfying the conditional expression (2), it occurs when focusing from infinity to a short distance. It is possible to satisfactorily correct the curvature of field. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (2) is set to, for example, 1.65, 1.60, 1.55, 1.50, 1.40, 1.30. , 1.20, 1.15, 1.10, 1.05, 1.00, and more preferably 0.97. Further, the lower limit of the conditional expression (2) is set to, for example, 0.23, 0.25, 0.28, 0.30, 0.33, 0.35, 0.38, 0.40, 0.42. Further, it is preferable to set it to 0.44.

Further, the variable magnification optical system preferably satisfies the following conditional expression (3).
0.15 <(-f1) / ff1 <1.30 ... (3)
However, f1: focal length of the first lens group

The above conditional expression (3) defines the ratio of the focal lengths of the first lens group G1 and the first focusing lens group. However, by satisfying the conditional expression (3), a predetermined shooting distance is secured. At the same time, it is possible to satisfactorily correct the curvature of field that occurs when focusing from infinity to a short distance. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (3) is set to, for example, 1.25, 1.20, 1.15, 1.10, 1.05, 1.00. , 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, 0.68, 0.65, and more preferably 0.63. Further, the lower limit of the conditional expression (3) is set to, for example, 0.18, 0.20, 0.23, 0.25, 0.28, 0.30, 0.33, 0.35, and further 0.38. It is preferable to set to.

Further, the variable magnification optical system preferably satisfies the following conditional expression (4).
0.10 <(−f1) / ff2 <0.95 ・ ・ ・ (4)

The above conditional expression (4) defines the ratio of the focal lengths of the first lens group G1 and the second focusing lens group. However, by satisfying the conditional expression (4), a predetermined shooting distance is secured. At the same time, it is possible to satisfactorily correct the curvature of field that occurs when focusing from infinity to a short distance. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (4) is set to, for example, 0.90, 0.80, 0.75, 0.70, 0.65, 0.60. , 0.58, 0.55, 0.53, and more preferably 0.50. Further, it is preferable to set the lower limit value of the conditional expression (4) to, for example, 0.13, 0.15, 0.18, 0.20, 0.21, and further 0.23.

In the above-mentioned variable magnification optical system, the first focusing lens group is preferably configured to move to the object side when the magnification is changed from infinity to close proximity. With this configuration, it is possible to better correct the curvature of field that occurs during focusing from infinity to a short distance.

Further, in the above-mentioned variable magnification optical system, the second focusing lens group is preferably configured to move to the image side when the magnification is changed from infinity to close proximity. With this configuration, it is possible to better correct the curvature of field that occurs during focusing from infinity to a short distance.

Further, the variable magnification optical system preferably satisfies the following conditional expression (5).
0.01 <(-MVF1) / MVF2 <30.0 ... (5)
However, MVF1: the amount of movement of the first focusing lens group when focusing from an infinite object to a short-distance object,
MVF2: The amount of movement of the second focusing lens group when focusing from an infinite object to a short-distance object,
The movement to the image side is positive.

The above conditional expression (5) defines the ratio of the moving distances of the two focusing lens groups at the time of focusing. However, by satisfying the conditional expression (5), a predetermined shooting distance can be secured. , The curvature of field that occurs when focusing from infinity to a short distance can be satisfactorily corrected. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (5) is set to, for example, 28.00, 25.00, 23.00, 20.00, 18,000, 15.00. , 13.00, 10.00, 8.00, 5.00, 3.00, 2.00, 1.80, 1.50, 1.20, and more preferably 1.00. Further, the lower limit of the conditional expression (5) is set to, for example, 0.05, 0.10, 0.15, 0.18, 0.20, 0.25, 0.28, 0.30, 0.33. It is preferably set to 0.35 and further to 0.38.

In the above-mentioned variable magnification optical system, it is preferable that the second focusing lens group is composed of one convex lens. With this configuration, it is possible to satisfactorily correct the curvature of field that occurs when focusing from infinity to a short distance without increasing the size of the focusing lens group.

In the above-mentioned variable magnification optical system, it is preferable that the first focusing lens group is composed of a junction lens of a convex lens and a concave lens. With this configuration, it is possible to satisfactorily correct the chromatic aberration of magnification that occurs when focusing from infinity to a short distance without increasing the size of the focusing lens group.

In the variable magnification optical system, it is preferable that the first lens group has three negative lenses in order from the object side. With this configuration, coma aberration and curvature of field in the wide-angle end state can be satisfactorily corrected.

Further, the variable magnification optical system preferably satisfies the following conditional expression (6).
−0.80 <βWF1 <0.80 ・ ・ ・ (6)
However, βWF1: lateral magnification of the first focusing lens group when focusing on an infinite object in the wide-angle end state.

The conditional expression (6) defines the range of the lateral magnification of the first focusing lens group at the time of focusing an object at infinity in the wide-angle end state. By satisfying the conditional equation (6), it is possible to suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object.
If the corresponding value of the conditional expression (6) is out of the specified range, the declination of the axial light beam becomes large, and it becomes difficult to correct the spherical aberration. Further, when the symmetry with respect to the main ray is poor, it becomes difficult to correct the distortion aberration and the coma aberration.

In order to ensure the effect of this embodiment, the upper limit of the conditional expression (6) is set to, for example, 0.78, 0.75, 0.73, 0.70, 0.68, 0.65, By setting it to 0.63, 0.60, 0.58, and further 0.55, the effect of this embodiment can be made more reliable. Further, the lower limit of the conditional expression (6) is set to, for example, -0.75, -0.70, -0.65, -0.60, -0.55, -0.50, -0.45, -0. By setting it to .40, -0.38, -0.35, -0.33, -0.31, -0.25, -0.20, and further -0.10, the effect of this embodiment can be obtained. It can be a more reliable source.

Further, the variable magnification optical system preferably satisfies the following conditional expression (7).
−0.80 <βWF2 <0.80 ・ ・ ・ (7)
However, βWF2; the lateral magnification of the second focusing lens group when focusing an object at infinity in the wide-angle end state.

The conditional expression (7) defines the range of the lateral magnification of the second focusing lens group when the infinity object is focused in the wide-angle end state. By satisfying the conditional equation (7), the lateral magnification of the second focusing lens group can suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object. it can.
If the corresponding value of the conditional expression (7) is out of the specified range, the declination of the axial light beam becomes large, and it becomes difficult to correct the spherical aberration. Further, when the symmetry with respect to the main ray is poor, it becomes difficult to correct distortion and co-aberration.

In order to ensure the effect of this embodiment, the upper limit of the conditional expression (7) is set to, for example, 0.78, 0.75, 0.73, 0.70, 0.68, 0.65, By setting it to 0.63, 0.60, 0.58, 0.55.0.53, and further 0.50, the effect of this embodiment can be made more reliable. Further, the lower limit of the conditional expression (7) is set to, for example, -0.78, -0.75, -0.73, -0.70, -0.50, -0.40, -0.30, -0. By setting it to .20 and further to −0.10, the effect of this embodiment can be made more reliable.

Further, the variable magnification optical system preferably satisfies the following conditional expression (8).
(ΒWF1 + (1 / βWF1)) ^-2 <0.25 ... (8)
However, βWF1: the lateral magnification of the first focusing lens group at the time of focusing an infinite object in the wide-angle end state.

The conditional expression (8) defines the range of the lateral magnification of the first focusing lens group at the time of focusing on an infinity object in the wide-angle end state in a form different from that of the conditional expression (6). By satisfying the conditional equation (8), the lateral magnification of the first focusing lens group can suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-range object. it can.
If the corresponding value of the conditional expression (8) is out of the specified range, the declination of the axial light beam becomes large, and it becomes difficult to correct the spherical aberration. Further, when the symmetry with respect to the main ray is poor, it becomes difficult to correct the distortion aberration and the coma aberration.

In order to ensure the effect of this embodiment, the upper limit of the conditional expression (8) is set to, for example, 0.
By setting 24, 0.23, 0.22, 0.20, 0.18, and further 0.16, the effect of the present embodiment can be made more reliable.

Further, the variable magnification optical system preferably satisfies the following conditional expression (9).
(ΒWF2 + (1 / βWF2)) ^-2 <0.25 ... (9)
However, βWF2: The lateral magnification of the second focusing lens group at the time of focusing an object at infinity in the wide-angle end state.

The conditional expression (9) defines the range of the lateral magnification of the second focusing lens group at the time of focusing on an infinity object in the wide-angle end state in a form different from that of the conditional expression (7). By satisfying the conditional equation (9), the lateral magnification of the second focusing lens group can suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object. it can.
If the corresponding value of the conditional expression (9) is out of the specified range, the declination of the axial light beam becomes large, and it becomes difficult to correct the spherical aberration. Further, when the symmetry with respect to the main ray is poor, it becomes difficult to correct the distortion aberration and the coma aberration.

In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (9) is set to, for example, 0.24, 0.23, 0.22, 0.20, 0.18, and further 0.16. By setting to, the effect of this embodiment can be made more reliable.

Subsequently, the manufacturing method of the optical system will be outlined with reference to FIG. In this manufacturing method, first, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a subsequent lens group are arranged in the lens barrel in order from the object side on the optical axis. Is arranged (step ST1). At this time, the succeeding lens group has a positive refractive power with the first focusing lens group having a positive refractive power. Next, when the magnification is changed from the wide-angle end to the telephoto end, the distance between the adjacent lens groups is changed (step ST2). Further, when focusing from infinity to a short distance, the first focusing lens group and the second focusing lens group are configured to move in the optical axis direction (step ST3).

According to the variable-magnification optical system according to the present embodiment described above, the camera (optical equipment) provided with the variable-magnification optical system, and the variable-magnification optical system manufactured by the above manufacturing method, the focusing lens group is compact and lightweight. This makes it possible to achieve high-speed AF and quietness during AF without increasing the size of the lens barrel, and further, aberration fluctuation during scaling from the wide-angle end state to the telephoto end state. In addition, aberration fluctuations during focusing from an infinity object to a short-range object can be suppressed satisfactorily.

Hereinafter, the variable magnification optical system ZL according to a specific embodiment of the above embodiment will be described with reference to the drawings. 1, FIG. 4, FIG. 7, FIG. 10, and FIG. 13 are cross-sections showing the configuration and refractive power distribution of the variable magnification optical system ZL {ZL (1) to ZL (5)} according to the first to fifth embodiments. It is a figure. In each cross-sectional view, the moving direction along the optical axis of each lens group when scaling from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow. Furthermore, the direction of movement when the focusing lens group focuses on a short-distance object from infinity is indicated by an arrow together with the word "focus".

In these figures (FIGS. 1, FIG. 4, FIG. 7, FIG. 10, and FIG. 13), each lens group is represented by a combination of reference numerals G and numbers, and each lens is represented by a combination of reference numerals L and numbers. In this case, in order to prevent the types and numbers of the symbols and numbers from becoming large and complicated, the lens group and the like are represented by independently using combinations of the symbols and numbers for each embodiment. Therefore, even if the same combination of reference numerals and numbers is used between the examples, it does not mean that they have the same configuration.

In FIGS. 2 and 3, FIG. 5, FIG. 5, FIG. 8, FIG. 9, FIG. 11 and FIG. 12, FIG. 14 and FIG. 15, FNO indicates the F number, NA indicates the numerical aperture, and Y indicates the image height. The spherical aberration diagram shows the value of the F number or numerical aperture corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height value, and the coma aberration diagram shows the value of each image height. d represents the d line (λ = 587.6 nm) and g represents the g line (λ = 435.8 nm). In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. The distortion diagram shows the distortion aberration based on the d-line, and the chromatic aberration of magnification diagram shows the chromatic aberration of magnification based on the g-line.

Tables 1 to 5 are shown below. Among them, Table 1 is the first embodiment, Table 2 is the second embodiment, Table 3 is the third embodiment, Table 4 is the fourth embodiment, and Table 5 is the first embodiment. It is a table which shows each specification data in 5 Examples. In each embodiment, the d-line (wavelength λ = 587.6 nm) and the g-line (wavelength λ = 435.8 nm) are selected as the calculation targets of the aberration characteristics.

In the [Overall Specifications] table, the focal length (f) indicates the focal length of the entire lens system at the wide-angle end (fw) and the telephoto end (ft). F. NO indicates an F number, 2ω indicates an angle of view (unit is ° (degrees), and ω is a half angle of view). TL indicates the distance from the frontmost surface of the lens to the final surface of the lens on the optical axis at infinity, plus BF, and BF is the lens on the optical axis at infinity. The air conversion distance (back focus) from the final plane to the image plane I is shown. These values are shown for each of the wide-angle end (W), intermediate focal length (M), and telephoto end (T) in each variable magnification state.

In the [Lens Specifications] table, the surface numbers (numbers in the columns indicated by the letters "planes") indicate the order of the optical planes from the object side along the direction in which the light beam travels, and R is the radius of curvature of each optical plane (the radius of curvature of each optical plane). The plane whose center of curvature is located on the image side is a positive value), D is the distance on the optical axis from each optical plane to the next optical plane (or image plane), and nd is the material of the optical member. The refractive index with respect to the d-line and νd indicate the Abbe number based on the d-line of the material of the optical member. The radius of curvature "∞" indicates a plane or an aperture, and (aperture S) indicates an aperture stop. The description of the refractive index nd of air = 1.00000 is omitted. When the lens surface is aspherical, the surface number is marked with * and the radius of curvature R indicates the paraxial radius of curvature.

In the table of [Aspherical surface data], the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (A). X (y) is the distance (zag amount) along the optical axis direction from the tangent plane at the aspherical apex to the position on the aspherical surface at the height y, and R is the radius of curvature of the reference sphere (near-axis radius of curvature). , Kappa is the conical constant, and Ai is the i-order aspherical coefficient. "E-n" indicates " ^{x10 -n".} For example, 1.234E-05 = 1.234 × 10 ^-5 . The second-order aspherical coefficient A2 is 0, and the description thereof is omitted.

X (y) = (y ² / R) / {1 + (1-κ × y ² / R ² ) ^1/2 } + A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ + A12 × y ¹²・・ ・ (A)

The table of [lens group data] shows the starting surface (the surface closest to the object) of each lens group and the focal length of each lens group.

The table of [Variable Interval Data] shows the surface spacing with the plane number in which the plane spacing is "variable" in the table showing [lens specifications]. Here, for each of the focus at infinity and short distance, the surface spacing at the wide-angle end (W), intermediate focal length (M), and telephoto end (T) in each variable magnification state is focused on the normal distance. It is shown separately for the case of focusing and the case of focusing at a close distance. The first line shows the total focal length f (when focusing on a normal distance) or the lateral magnification β (when focusing on a close distance) in each variable magnification state. The last line shows the surface spacing of the part where the surface spacing is "Bf".

In the [Magnification] table, the lateral magnification βF1 of the first focusing lens group and the lateral magnification βF2 of the second focusing lens group are shown at the wide-angle end (W), the intermediate focal length (M), and the telephoto end (T). Each variable magnification state is shown separately for the case of focusing on a normal distance and the case of focusing on a close distance. The [Other Specifications] table shows the focal length (ff1) of the first focusing lens group and the focal length (ff2) of the second focusing lens group. Further, the amount of movement of the first focusing lens group (MVF1) and the amount of movement of the second focusing lens group (MVF2) when focusing from an infinity object to a short-range object (the closest object) in the wide-angle end state. ) Is shown.

A table of [conditional expression corresponding values] is provided at the end of the description of all the examples (1st to 5th examples). In this table, the values corresponding to each conditional expression are summarized for all the examples (1st to 5th examples).

Hereinafter, in all the specification values, "mm" is generally used for the focal length f, the radius of curvature R, the plane spacing D, other lengths, etc., unless otherwise specified, but the optical system is expanded proportionally. Alternatively, it is not limited to this because the same optical performance can be obtained even if the proportional reduction is performed.

The description of the table so far is common to all the examples, and the duplicate description below is omitted.

(First Example)
The first embodiment will be described with reference to FIGS. 1 to 3 and Table 1. FIG. 1 is a diagram showing a lens configuration of a variable magnification optical system according to the first embodiment. The variable magnification optical system ZL (1) according to the first embodiment has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and an aperture arranged in order from the object side. Aperture S, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, and a third lens group having a positive refractive power. It is composed of 6 lens groups G6. When scaling from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move in the directions indicated by the arrows in FIG. Change. The lens group consisting of the third to sixth lens groups G3 to G6 corresponds to the subsequent lens group GR. The symbol (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this also applies to all the following examples.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a negative meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of L13 and a biconvex positive lens L14.

The negative meniscus lens L11 is a hybrid type lens in which a resin layer L11b is provided on the image side surface of the glass lens body L11a. The image-side surface of the resin layer L11b is an aspherical surface, and the negative meniscus lens L11 is a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 1 is the surface of the lens body L11a on the object side, the surface number 2 is the surface of the lens body L11a on the image side and the surface of the resin layer L11b on the object side (the surface where both are joined). ), The surface number 3 indicates the surface of the resin layer L11b on the image side.

The negative meniscus lens L12 is also a hybrid type lens configured by providing a resin layer L12b on the object-side surface of the glass lens body L12a. The surface of the resin layer L12b on the object side is an aspherical surface, and the negative meniscus lens L12 is also a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 4 is the surface of the resin layer L12ba on the object side, the surface number 5 is the surface of the resin layer L12b on the image side and the surface of the lens body L12a on the object side (the surface where both are joined). ), The surface number 6 indicates the surface of the lens body L12a on the image side.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a negative meniscus lens L22 having a convex surface facing the object side, and a biconvex positive lens L23 arranged in order from the object side. Consists of. The aperture diaphragm S is provided near the image side of the second lens group G2 and moves together with the second lens group G2 at the time of scaling.

The third lens group G3 is composed of a biconvex positive lens L31 and a junction lens of a negative meniscus lens L32 with a concave surface facing the object side.

The fourth lens group G4 is composed of a biconcave negative lens L41.

The fifth lens group G5 is composed of a positive meniscus lens L51 with a convex surface facing the object side.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side, a negative meniscus lens L62 having a convex surface facing the object side, and a junction lens of a biconvex positive lens L63. The surface of the positive meniscus lens L61 on the image side is an aspherical surface.

In this embodiment, the third lens group G3 constitutes the first focusing lens group, and the fifth lens group G5 constitutes the second focusing lens group. The third lens group G3 moves to the object side and the fifth lens group G5 moves to the image side according to the change from the in-focus state to the long-distance object (infinity object) to the in-focus state to the short-distance object. ..

Table 1 below lists the specifications of the variable magnification optical system according to the first embodiment.

(Table 1)
[Overall specifications]
Focal length (f) 10.3 (fw) --21.5 (ft)
W MT
F.NO 4.58461 4.97276 5.66887
2ω 55.20233 47.83147 32.93905
Air conversion TL 121.30256 111.17694 103.94431
Air conversion BF 22.07112 26.72635 37.73788
[Lens specifications]
Surface RD nd νd
1 66.0078 2.40 1.77250 49.61
2 17.8896 0.20 1.56093 36.64
* 3 13.0203 10.39 1.00000
* 4 69.5573 0.20 1.55389 38.09
5 74.5519 1.50 1.77250 49.61
6 25.3147 4.66 1.00000
7 120.000 1.30 1.77250 49.61
8 31.6192 3.48 1.00000
9 32.2527 4.63 1.71736 29.58
10 -749.923 Variable 1.00000
11 16.9525 2.04 1.72825 28.38
12 55.8636 0.80 1.91082 35.25
13 12.8077 1.51 1.00000
14 14.4747 2.31 1.51680 63.88
15 -90.0426 1.86 1.00000
16 0 Variable 1.00000 Aperture S
17 23.0619 2.94 1.53172 48.78
18 -15.5169 0.90 1.90366 31.27
19 -26.4746 Variable 1.00000
20 -831.453 0.80 1.91082 35.25
21 25.1602 Variable 1.00000
22 16.4236 1.61 1.51680 63.88
23 30.0899 Variable 1.00000
24 -59.9852 1.35 1.53110 55.91
* 25 -33.4579 0.50 1.00000
26 78.9399 0.80 1.91082 35.25
27 19.5552 4.48 1.48749 70.24
28 -44.7036 Variable 1.00000
29 0 2.00 1.51680 63.88
30 0 Bf 1.00000
Image plane (I) ∞
[Aspherical data]
Third side κ = 0.0944
A4 ＝ -9.40E-06 A6 ＝ -1.18E-08 A8 ＝ 3.95E-11 A10 ＝ 5.57E-13
Side 4 κ = -25.413
A4 ＝ -4.18E-06 A6 ＝ 2.67E-08 A8 ＝ 1.51E-10 A10 ＝ -2.82E-13
Side 25 κ = 1.00
A4 ＝ 6.81E-05 A6 ＝ 4.87E-07 A8 ＝ -4.55E-09 A10 ＝ 5.03E-11
[Lens group data]
Focal length
G1 1 -18.7654
G2 11 51.03682
G3 17 30.51806
G4 20 -26.8004
G5 22 67.26356
G6 24 123.1616
[Variable interval data]
W MT W Close M Close T Close
f (β) 10.30 13.01 21.50 -0.08318 -0.14416 -0.19832
d10 32.8753 20.3228 2.00000 32.8753 20.3228 2.00000
d16 5.0342 3.80869 2.76786 4.55905 3.16979 1.63154
d19 1.49446 1.80677 3.48694 1.96961 2.44567 4.62326
d21 0.69387 0.29529 2.00441 1.77009 1.77881 4.32648
d23 8.45918 7.54262 5.2728 7.38297 6.0591 2.95073
d28 20.65256 25.30779 36.31931 20.65256 25.30779 36.31931
Bf 0.1 0.1 0.1 0.1 0.1 0.1 0.1
[magnification]
W MT W Close M Close T Close βF1 0.18476 0.12404 -0.04382 0.17725 0.11351 -0.0685
βF2 0.37405 0.2813 0.0176 0.39005 0.30335 0.05212
[Other specifications]
ff1 30.518
ff2 67.264
MVF1w -0.475
MVF2w 1.07621

2 (A), (B) and (C) are aberration diagrams at infinity focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the first embodiment, respectively. is there. 3 (A), (B) and (C) are aberration diagrams at the time of short-range focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the first embodiment, respectively. is there.

In each aberration diagram of FIGS. 2A to 2C, FNO indicates an F number and Y indicates an image height. The spherical aberration diagram shows the value of the F number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum value of the image height, and the transverse aberration diagram shows the value of each image height. In each aberration diagram of FIGS. 3A to 3C, NA indicates the numerical aperture and Y indicates the image height. The spherical aberration diagram shows the numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma aberration diagram shows the value of each image height. Further, in each aberration diagram, d indicates the d line (wavelength λ = 587.6 nm), and g indicates the g line (wavelength λ = 435.8 nm). In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. In the aberration diagrams of each of the following examples, the same reference numerals as those of the present embodiment will be used, and duplicate description will be omitted.

From each aberration diagram, the variable magnification optical system according to the first embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance, and further, at the time of short-distance focusing. It can be seen that also has excellent imaging performance.

(Second Example)
The second embodiment will be described with reference to FIGS. 4 to 6 and Table 2. FIG. 4 is a diagram showing a lens configuration of the variable magnification optical system according to the second embodiment. The variable magnification optical system ZL (2) according to the second embodiment has a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and an aperture arranged in order from the object side. Aperture S, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, and a third lens group having a positive refractive power. It is composed of 6 lens groups G6. When scaling from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move in the directions indicated by the arrows in FIG. Change. The lens group consisting of the third to sixth lens groups G3 to G6 corresponds to the subsequent lens group GR.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a negative meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of L13 and a biconvex positive lens L14.

The negative meniscus lens L11 is a hybrid type lens in which a resin layer L11b is provided on the image side surface of the glass lens body L11a. The image-side surface of the resin layer L11b is an aspherical surface, and the negative meniscus lens L11 is a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 1 is the surface of the lens body L11a on the object side, the surface number 2 is the surface of the lens body L11a on the image side and the surface of the resin layer L11b on the object side (the surface where both are joined). ), The surface number 3 indicates the surface of the resin layer L11b on the image side.

The negative meniscus lens L12 is also a hybrid type lens configured by providing a resin layer L12b on the object-side surface of the glass lens body L12a. The surface of the resin layer L12b on the object side is an aspherical surface, and the negative meniscus lens L12 is also a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 4 is the surface of the resin layer L12ba on the object side, the surface number 5 is the surface of the resin layer L12b on the image side and the surface of the lens body L12a on the object side (the surface where both are joined). ), The surface number 6 indicates the surface of the lens body L12a on the image side.

The second lens group G2 is composed of a junction lens of a biconvex positive lens L21 and a biconcave negative lens L22 arranged in order from the object side, and a biconvex positive lens L23. The aperture diaphragm S is provided near the image side of the second lens group G2 and moves together with the second lens group G2 at the time of scaling.

The third lens group G3 is composed of a biconvex positive lens L31 and a junction lens of a negative meniscus lens L32 with a concave surface facing the object side.

The fourth lens group G4 is composed of a biconcave negative lens L41.

The fifth lens group G5 is composed of a positive meniscus lens L51 with a convex surface facing the object side.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side, a negative meniscus lens L62 having a convex surface facing the object side, and a junction lens of a biconvex positive lens L63. The surface of the positive meniscus lens L61 on the image side is an aspherical surface.

In this embodiment, the third lens group G3 constitutes the first focusing lens group, and the fifth lens group G5 constitutes the second focusing lens group. The third lens group G3 moves to the object side and the fifth lens group G5 moves to the image side according to the change from the in-focus state to the long-distance object (infinity object) to the in-focus state to the short-distance object. ..

Table 2 below lists the specifications of the variable magnification optical system according to the second embodiment.

(Table 2)
[Overall specifications]
Focal length (f) 10.3 (fw) --19.32 (ft)
W MT
F.NO 4.6301 5.23998 5.83553
2ω 56.39754 44.87543 37.36057
Air conversion TL 125.91266 113.62769 107.76397
Air conversion BF 20.44108 26.46282 35.19053
[Lens specifications]
Surface RD nd νd
1 66.922 2.40 1.77250 49.61
2 17.7951 0.20 1.56093 36.64
* 3 13.0065 10.96 1.00000
* 4 44.9602 0.20 1.55389 38.09
5 46.0476 1.50 1.77250 49.61
6 20.8512 5.49 1.00000
7 120.000 1.30 1.77250 49.61
8 36.1878 5.92 1.00000
9 37.0286 3.92 1.71736 29.58
10 -749.889 Variable 1.00000
11 51.0535 2.05 1.72825 28.38
12 -32.8904 0.80 1.91082 35.25
13 40.7464 1.22 1.00000
14 22.0824 2.28 1.51680 63.88
15 -35.2067 1.63 1.00000
16 0 Variable 1.00000 Aperture S
17 28.7991 2.69 1.53172 48.78
18 -15.1315 0.90 1.90366 31.27
19 -34.7347 Variable 1.00000
20 -79.1048 0.80 1.91082 35.25
21 55.1803 Variable 1.00000
22 18.6322 1.56 1.51680 63.88
23 31.533 Variable 1.00000
24 -60.0021 1.43 1.53110 55.91
* 25 -33.4796 0.50 1.00000
26 49.3873 0.80 1.91082 35.25
27 15.8208 5.23 1.48749 70.24
28 -53.1349 Variable 1.00000
29 0 2.00 1.51680 63.88
30 0 Bf 1.00000
Image plane (I) ∞
[Aspherical data]
Third side
κ = 0.1002
A4 ＝ -9.02E-06 A6 ＝ -1.45E-08 A8 ＝ 8.99E-11 A10 ＝ 4.58E-13
4th side
κ = -4.6078
A4 ＝ -6.39E-06 A6 ＝ 4.84E-08 A8 ＝ 1.53E-10 A10 ＝ -2.96E-13
25th page
κ = 1.000
A4 ＝ 4.61E-05 A6 ＝ 2.921E-07 A8 ＝ -3.00E-09 A10 ＝ 2.17E-11
[Lens group data]
Focal length
G1 1 -20.0295
G2 11 40.65621
G3 17 50.20726
G4 20 -35.5873
G5 22 84.63536
G6 24 121.5811
[Variable interval data]
W MT W Close M Close T Close
f (β) 10.29984 12.99976 19.31945 -0.05582 -0.0664 -0.0967
d10 32.5917 18.1044 2.00000 32.5917 18.1044 2.0000
d16 2.94702 2.78457 4.11328 2.3937 2.02381 2.79333
d19 1.5000 1.54877 2.3198 2.05332 2.30953 3.63975
d21 3.20723 1.00000 1.50000 3.95327 1.98746 3.21594
d23 11.4491 9.9506 8.86383 10.70306 8.96314 7.14789
d28 19.02252 25.04425 33.77196 19.03768 25.06574 33.81755
Bf 0.1 0.1 0.1 0.1 0.1 0.1 0.1
[magnification]
WM T W Close M Close T Close βF1 0.42189 0.37491 0.28287 0.41447 0.36447 0.26369
βF2 0.48041 0.38803 0.21395 0.48897 0.39928 0.23315
[Other specifications]
ff1 50.207
ff2 84.635
MVF1w -0.568
MVF2w 0.73087

5 (A), 5 (B), and 5 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the second embodiment, respectively. It is a diagram of various aberrations of. 6 (A), 6 (B), and 6 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the second embodiment, respectively. It is a diagram of various aberrations of. From each aberration diagram, the variable magnification optical system according to the second embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance, and further, at the time of short-distance focusing. It can be seen that also has excellent imaging performance.

(Third Example)
The third embodiment will be described with reference to FIGS. 7 to 9 and Table 3. FIG. 7 is a diagram showing a lens configuration of the variable magnification optical system according to the third embodiment. The variable magnification optical system ZL (3) according to the third embodiment is
The first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, the aperture aperture S, and the third lens group G3 having a negative refractive power arranged in order from the object side. It is composed of a fourth lens group G4 having a positive refractive power and a fifth lens group G5 having a positive refractive power. When scaling from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by the arrows in FIG. Change. The lens group consisting of the third to fifth lens groups G3 to G5 corresponds to the subsequent lens group GR.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a negative meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of L13 and a biconvex positive lens L14.

The negative meniscus lens L11 is a hybrid type lens in which a resin layer L11b is provided on the image side surface of the glass lens body L11a. The image-side surface of the resin layer L11b is an aspherical surface, and the negative meniscus lens L11 is a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 1 is the surface of the lens body L11a on the object side, the surface number 2 is the surface of the lens body L11a on the image side and the surface of the resin layer L11b on the object side (the surface where both are joined). ), The surface number 3 indicates the surface of the resin layer L11b on the image side.

The negative meniscus lens L12 is also a hybrid type lens configured by providing a resin layer L12b on the object-side surface of the glass lens body L12a. The surface of the resin layer L12b on the object side is an aspherical surface, and the negative meniscus lens L12 is also a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 4 is the surface of the resin layer L12ba on the object side, the surface number 5 is the surface of the resin layer L12b on the image side and the surface of the lens body L12a on the object side (the surface where both are joined). ), The surface number 6 indicates the surface of the lens body L12a on the image side.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a positive meniscus lens L23 having a concave surface facing the object side, and a negative meniscus lens L24 having a concave surface facing the object side, which are arranged in order from the object side. Consists of a bonded lens. The aperture diaphragm S is provided near the image side of the second lens group G2 and moves together with the second lens group G2 at the time of scaling.

The third lens group G3 is composed of a biconvex positive lens L31, a junction lens of a negative meniscus lens L32 with a concave surface facing the object side, and a biconcave negative lens L33. In the third lens group G3, the junction lens of the positive lens L31 and the negative meniscus lens L32 constitutes the front lens group G3A, and the negative lens L33 constitutes the rear lens group G3B. Then, the front lens group G3A constitutes the first focusing lens group.

The fourth lens group G4 is composed of a positive meniscus lens L41 having a convex surface facing the object side. The fourth lens group G4 constitutes the second focusing lens group.

The fifth lens group G5 is composed of a positive meniscus lens L51 having a concave surface facing the object side, a negative meniscus lens L52 having a convex surface facing the object side, and a biconvex positive lens L53. The surface of the positive meniscus lens L51 on the image side is an aspherical surface.

In this embodiment, a part of the image side of the third lens group G3 (front lens group G3A) constitutes the first focusing lens group, and the fourth lens group G4 constitutes the second focusing lens group. .. Then, a part of the image side of the third lens group G3 (front lens group G3A) becomes an object according to the change from the in-focus state to the long-distance object (infinity object) to the in-focus state to the short-range object. The fourth lens group G4 moves to the image side.

Table 3 below lists the specifications of the variable magnification optical system according to the third embodiment.

(Table 3)
[Overall specifications]
Focal length (f) 11.3 (fw) ―― 19.3 (ft)
WMT
F.NO 4.61296 5.00943 5.68446
2ω 52.82737 44.07011 36.15833
Air conversion TL 120.87241 108.97567 108.40436
Air conversion BF 16.52159 24.01249 31.04985
[Lens specifications]
Surface RD nd νd
1 42.2613 2.40 1.77250 49.61
2 16.1746 0.20 1.56093 36.64
* 3 13.0027 10.79 1.00000
* 4 99.2765 0.20 1.55389 38.09
5 91.8259 1.50 1.77250 49.61
6 21.4633 4.89 1.00000
7 120.0000 1.30 1.77250 49.61
8 59.6747 7.41 1.00000
9 43.1309 3.59 1.71736 29.58
10 -750.0000 Variable 1.00000
11 23.8089 1.88 1.51680 63.88
12 101.019 2.23 1.00000
13 -114.581 0.80 1.91082 35.25
14 -40.4733 1.43 1.72825 28.38
15 -52.685 1.28 1.00000
16 0 Variable 1.00000 Aperture S
17 26.5144 2.55 1.53172 48.78
18 -14.8795 0.90 1.90366 31.27
19 -32.8111 Variable 1.00000
20 -1986.21 0.80 1.91082 35.25
21 21.4616 Variable 1.00000
22 19.6202 1.79 1.51680 63.88
23 103.813 Variable 1.00000
24 -59.9998 1.56 1.53110 55.91
* 25 -33.5052 0.50 1.00000
26 34.3198 0.80 1.91082 35.25
27 15.1432 5.39 1.48749 70.24
28 -259.404 Variable 1.00000
29 0 2.00 1.51680 63.88
30 0 BF 1.00000
Image plane (I) ∞
[Aspherical data]
Third side
κ = 0.2869
A4 ＝ 1.03E-05 A6 ＝ 2.72E-08 A8 ＝ -1.10E-10 A10 ＝ 8.60E-13
4th side
κ = 12.1204
A4 ＝ 1.25E-06 A6 ＝ -1.11E-08 A8 ＝ 1.38E-10 A10 ＝ -2.23E-13
25th page
κ = 1.000
A4 ＝ 2.71E-05 A6 ＝ 7.25E-08 A8 ＝ -6.06E-10 A10 ＝ 6.36E-12
[Lens group data]
Focal length
G1 1 -22.49113
G2 11 38.13818
G3 17 -58.34838
G4 22 46.47508
G5 24 126.00073
[Variable interval data]
W M T W Close M Close T Close
f (β) 11.2996 14.8995 19.3194 -0.05898 -0.07401 -0.09672
d10 30.4632 13.8849 2.0000 30.4632 13.8849 2.0000
d16 2.76367 2.80224 4.56673 2.11089 2.09423 3.56283
d19 1.5000 1.5000 1.5000 2.15278 2.20801 2.5039
d21 1.80903 2.00882 6.09908 2.7882 2.78763 7.10298
d23 13.6245 10.5768 8.99828 12.64533 9.79799 7.99438
d28 15.10303 22.59384 29.63121 15.10303 22.59384 29.63121
Bf 0.1 0.10008 0.10008 0.1 0.10008 0.10008
[magnification]
W M T W Close M Close T Close βF1 0.43161 0.38253 0.32802 0.42303 0.37074 0.30964
βF2 0.11541 -0.06604 -0.30118 0.13648 -0.04929 -0.27958
[Other specifications]
ff1 44.31219
ff2 46.47508
MVF1w -0.6528
MVF2w 0.97917

8 (A), 8 (A), and 8 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the third embodiment, respectively. It is a diagram of various aberrations of. 9 (A), 9 (B), and 9 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the third embodiment, respectively. It is a diagram of various aberrations of. From each aberration diagram, the variable magnification optical system according to the third embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance, and further, at the time of short-distance focusing. It can be seen that also has excellent imaging performance.

(Fourth Example)
A fourth embodiment will be described with reference to FIGS. 10 to 12 and Table 4. FIG. 10 is a diagram showing a lens configuration of the variable magnification optical system according to the fourth embodiment. The variable magnification optical system ZL (4) according to the fourth embodiment has the first lens group G1 having a negative refractive power arranged in order from the object side, and the aperture aperture S having a positive refractive power in the middle. It is composed of a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a positive refractive power. When scaling from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in the directions indicated by the arrows in FIG. Change. The lens group consisting of the third to fourth lens groups G3 to G4 corresponds to the subsequent lens group GR.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a biconcave negative lens L13 arranged in order from the object side. It is composed of a convex positive lens L14.

The negative meniscus lens L11 is a hybrid type lens in which a resin layer L11b is provided on the image side surface of the glass lens body L11a. The image-side surface of the resin layer L11b is an aspherical surface, and the negative meniscus lens L11 is a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 1 is the surface of the lens body L11a on the object side, the surface number 2 is the surface of the lens body L11a on the image side and the surface of the resin layer L11b on the object side (the surface where both are joined). ), The surface number 3 indicates the surface of the resin layer L11b on the image side.

The negative meniscus lens L12 is also a hybrid type lens configured by providing a resin layer L12b on the object-side surface of the glass lens body L12a. The surface of the resin layer L12b on the object side is an aspherical surface, and the negative meniscus lens L12 is also a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 4 is the surface of the resin layer L12ba on the object side, the surface number 5 is the surface of the resin layer L12b on the image side and the surface of the lens body L12a on the object side (the surface where both are joined). ), The surface number 6 indicates the surface of the lens body L12a on the image side.

The second lens group G2 includes a junction lens of a biconvex positive lens L21 and a biconcave negative lens L22 arranged in order from the object side, a positive meniscus lens L23 with a concave surface facing the object side, and a biconvex shape. It is composed of a positive lens L24 and a junction lens of a negative meniscus lens L25 with a concave surface facing the object side. The aperture diaphragm S is located between the positive meniscus lens L23 and the positive lens L24 and is provided inside the second lens group G2, and moves together with the second lens group G2 at the time of scaling. As shown in the figure, the second lens group G2 includes a front lens group G2A (composed of a junction lens of a positive lens L21 and a negative lens L22), an intermediate lens group G2B (composed of a positive meniscus lens L23), and a rear side. It is composed of a lens group G2C (composed of a junction lens of a positive lens L24 and a negative meniscus lens L25).

The third lens group G3 is composed of a biconcave negative lens L31 and a positive meniscus lens L32 with a convex surface facing the object side. As shown in the figure, the third lens group G3 is composed of a front lens group G3A (composed of a negative lens L31) and a rear lens group G3B (composed of a positive meniscus lens L32).

The fourth lens group G4 is composed of a positive meniscus lens L41 having a concave surface facing the object side, a biconcave negative lens L42, and a biconvex positive lens L43. The surface of the positive meniscus lens L41 on the image side is an aspherical surface.

In this embodiment, the rear lens group G2C of the second lens group G2 constitutes the first focusing lens group.
The rear lens group G3B of the third lens group G3 constitutes the second focusing lens group. The first in-focus lens group (rear lens group G2C) moves to the object side and the second in-focus state according to the change from the in-focus state to the long-distance object (infinity object) to the in-focus state to the short-range object. The focusing lens group (rear lens group G3B) moves to the image side.

Further, the intermediate lens group G2B (positive meniscus lens L23) constituting the second lens group G2 is moved so as to have a component in the direction perpendicular to the optical axis, and is an anti-vibration lens group for correcting image blurring due to camera shake or the like. It has become.

Table 4 below lists the specifications of the variable magnification optical system according to the fourth embodiment.

(Table 4)
[Overall specifications]
Focal length (f) 10.3 (fw) ―― 19.4 (ft)
WMT
F.NO 4.6301 5.23998 5.83553
2ω 56.39754 44.87543 37.36057
Air conversion TL 127.19237 118.45802 118.27894
Air conversion BF 38.11835 45.70695 53.49651
[Lens specifications]
Surface RD nd νd
1 72.1955 2.40 1.77250 49.62
2 18.1031 0.20 1.56093 36.64
* 3 12.8098 13.50 1.00000
* 4 38.7281 0.20 1.55389 38.09
5 33.8000 1.50 1.80610 40.97
6 15.4815 6.41 1.00000
7 -213.939 1.30 1.69680 55.52
8 48.4224 0.10 1.00000
9 25.7571 4.15 1.71736 29.57
10 -228.544 Variable 1.00000
11 25.4457 2.55 1.72825 28.38
12 -15.8585 0.80 1.91082 35.25
13 28.6288 1.92 1.00000
14 -195.244 1.58 1.51680 63.88
15 -24.949 1.45 1.00000
16 0 Variable 1.00000 Aperture S
17 21.5531 3.28 1.53172 48.78
18 -15.0486 0.90 1.91082 35.25
19 -23.5039 Variable 1.00000
20 -112.948 0.80 1.91082 35.25
21 28.2311 Variable 1.00000
22 18.6211 1.83 1.51680 63.88
23 77.6694 Variable 1.00000
24 -59.8503 1.36 1.53110 55.91
* 25 -34.4312 0.60 1.00000
26 -136.828 0.80 1.91082 35.25
27 21.0189 5.60 1.48749 70.31
28 -15.2735 Variable 1.00000
29 0 2.00 1.51680 63.88
30 0 Bf 1.00000
Image plane (I) ∞
[Aspherical data]
Third side
κ = 0.0387
A4 ＝ -1.10E-05 A6 ＝ -2.98E-08 A8 ＝ 1.59E-10 A10 ＝ 2.68E-13
4th side
κ = 0.2082
A4 ＝ -3.60E-06 A6 ＝ 8.87E-08 A8 ＝ 2.10E-10 A10 ＝ -2.30E-13
25th page
κ = 1.000
A4 ＝ 5.63E-05 A6 ＝ 4.89E-08 A8 ＝ -2.05E-09 A10 ＝ 3.5E-11
[Lens group data]
Focal length
G1 1 -16.3772
G2 11 24.84907
G3 20 -56.2908
G4 24 70.2103
[Variable interval data]
W M T W Close M Close T Close
F (β) 10.31023 15.00257 19.4 -0.05436 -0.07709 -0.10236
d10 26.1646 9.84165 1.87301 26.1646 9.84165 1.87301
d16 1.80195 1.80195 1.80195 1.32479 1.00051 0.20687
d19 1.45964 2.6478 3.18161 1.9368 3.44925 4.77669
d21 0.6974 0.6974 0.6974 1.89031 1.73928 1.97347
d23 5.72006 4.5319 3.99809 4.52716 3.49002 2.72203
d28 36.69978 44.28838 52.07794 36.69978 44.28838 52.07794
Bf 0.1 0.1 0.1 0.1 0.1 0.1 0.1
[magnification]
W M T W Close M Close T Close βF1 -0.29802 -0.49787 -0.68391 -0.31172 -0.53124 -0.75951
βF2 -0.67094 -1.34785 -2.55372 -0.64551 -1.32564 -2.52651
[Other specifications]
ff1 26.66669
ff2 46.89864
MVF1w -0.477
MVF2w 1.1929

11 (A), 11 (B), and 11 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fourth embodiment, respectively. It is a diagram of various aberrations of. 12 (A), 12 (B), and 12 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fourth embodiment, respectively, at the time of short-distance focusing. It is a diagram of various aberrations of. From each aberration diagram, the variable magnification optical system according to the fourth embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance, and further, at the time of short-distance focusing. It can be seen that also has excellent imaging performance.

(Fifth Example)
A fifth embodiment will be described with reference to FIGS. 13 to 15 and Table 5. FIG. 13 is a diagram showing a lens configuration of the variable magnification optical system according to the fifth embodiment. In the variable magnification optical system ZL (5) according to the fifth embodiment, the first lens group G1 having a negative refractive power and the second lens group G2 having a negative refractive power arranged in order from the object side are positive. The third lens group G3 having the refractive power of, the aperture aperture S, the fourth lens group G4 having the positive refractive power, the fifth lens group G5 having the negative refractive power, and the third lens group G5 having the positive refractive power. It is composed of a 6-lens group G6 and a 7th lens group G7 having a positive refractive power. When scaling from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. The lens group consisting of the third to seventh lens groups G3 to G7 corresponds to the subsequent lens group GR.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, and a negative meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side. It is composed of L13 and a biconvex positive lens L14.

The negative meniscus lens L11 is a hybrid type lens in which a resin layer L11b is provided on the image side surface of the glass lens body L11a. The image-side surface of the resin layer L11b is an aspherical surface, and the negative meniscus lens L11 is a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 1 is the surface of the lens body L11a on the object side, the surface number 2 is the surface of the lens body L11a on the image side and the surface of the resin layer L11b on the object side (the surface where both are joined). ), The surface number 3 indicates the surface of the resin layer L11b on the image side.

The negative meniscus lens L12 is also a hybrid type lens configured by providing a resin layer L12b on the object-side surface of the glass lens body L12a. The surface of the resin layer L12b on the object side is an aspherical surface, and the negative meniscus lens L12 is also a composite aspherical surface lens. In the [Lens Specifications] column described later, the surface number 4 is the surface of the resin layer L12ba on the object side, the surface number 5 is the surface of the resin layer L12b on the image side and the surface of the lens body L12a on the object side (the surface where both are joined). ), The surface number 6 indicates the surface of the lens body L12a on the image side.

The second lens group G2 is composed of a junction lens of a biconvex positive lens L21 and a biconcave negative lens L22.

The third lens group G3 is composed of a biconvex positive lens L31. The aperture diaphragm S is provided near the image side of the third lens group G3 and moves together with the third lens group G3 at the time of scaling.

The fourth lens group G4 is composed of a biconvex positive lens L41 and a junction lens of a negative meniscus lens L42 with a concave surface facing the object side.

The fifth lens group G5 is composed of a biconcave negative lens L51.

The sixth lens group G6 is composed of a positive meniscus lens L61 with a convex surface facing the object side.

The seventh lens group G7 is composed of a positive meniscus lens L71 having a concave surface facing the object side, a negative meniscus lens L72 having a convex surface facing the object side, and a junction lens of a biconvex positive lens L73. The surface of the positive meniscus lens L71 on the image side is an aspherical surface.

In this embodiment, the fourth lens group G4 constitutes the first focusing lens group, and the sixth lens group G6 constitutes the second focusing lens group. The first in-focus lens group (fourth lens group G4) moves to the object side and the second in-focus state according to the change from the in-focus state to the long-distance object (infinity object) to the in-focus state to the short-range object. The focusing lens group (sixth lens group G6) moves to the image side.

Table 5 below lists the specifications of the variable magnification optical system according to the fifth embodiment.

(Table 5)
[Overall specifications]
Focal length (f) 10.3 (fw) ―― 19.3 (ft)
WMT
F.NO 4.6683 4.96374 5.80239
2ω 55.25456 48.20506 35.45169
Air conversion TL 121.01438 108.39582 103.93683
Air conversion BF 16.95795 23.02697 29.43842
[Lens specifications]
Surface RD nd νd
1 58.6074 2.40 1.77250 49.61
2 17.5078 0.20 1.56093 36.64
* 3 13.0042 9.90 1.00000
* 4 50.3458 0.20 1.55389 38.09
5 56.8198 1.50 1.77250 49.61
6 21.5929 5.45 1.00000
7 119.999 1.30 1.77250 49.61
8 39.5142 7.63 1.00000
9 41.6577 3.67 1.71736 29.58
10 -749.999 Variable 1.00000
11 37.7166 1.91 1.72825 28.38
12 -96.4635 0.80 1.91082 35.25
13 32.6266 Variable 1.00000
14 18.8176 2.29 1.51680 63.88
15 -41.5207 1.71 1.00000
16 0 Variable 1.00000 Aperture S
17 28.3401 2.69 1.53172 48.78
18 -14.0687 0.90 1.90366 31.27
19 -34.3736 Variable 1.00000
20 -67.0447 0.80 1.91082 35.25
21 45.6913 Variable 1.00000
22 18.0512 1.59 1.51680 63.88
23 34.0298 Variable 1.00000
24 -60.0006 1.35 1.53110 55.91
* 25 -33.4648 0.91 1.00000
26 42.1746 0.80 1.91082 35.25
27 15.6452 4.94 1.48749 70.24
28 -103.065 29.88 1.00000
29 0 2.00 1.51680 63.88
30 0 0.10 1.00000
Image plane (I) ∞
[Aspherical data]
Third side
κ = 0.1402
A4 ＝ -5.51E-06 A6 ＝ -1.51E-08 A8 ＝ 2.32E-11 A10 ＝ 6.51E-13
4th side
κ =-5.3009
A4 ＝ -9.86E-06 A6 ＝ 3.87E-08 A8 ＝ 1.40E-10 A10 ＝ -2.96E-13
25th page
κ = 1.000
A4 ＝ 6.04E-05 A6 ＝ 5.21E-07 A8 ＝ -5.53E-09 A10 ＝ 4.16E-11
[Lens group data]
Focal length
G1 1 -20.6289
G2 11 -103.51107
G3 14 25.38363
G4 17 53.4659
G5 20 -29.73283
G6 22 71.94709
G7 24 150.4283
[Variable interval data]
W M T W Close M Close T Close
F (β) 10.29989 12.99987 19.31936 -0.05435 -0.06458 -0.09437
d10 32.0027 12.9451 2.0000 32.0027 12.9451 2.0000
d13 1.21092 3.95802 1.07653 1.21092 3.95802 1.07653
d16 2.7494 2.86437 3.6529 2.29199 2.33306 2.65189
d19 1.5000 0.40476 2.07238 1.95741 0.93607 3.07339
d21 2.39681 1.0000 1.5000 2.83592 1.31879 2.31081
d23 11.2541 9.43894 8.26897 10.81499 9.12015 7.45816
d28 15.53939 22.84512 29.83997 15.55377 22.86546 29.88341
Bf 0.1 0.1 0.1 0.1 0.1 0.1 0.1
[magnification]
W M T W Close M Close T Close βF1 0.52437 0.50057 0.42462 0.51772 0.49189 0.4088
βF2 0.45968 0.34278 0.20627 0.46552 0.3468 0.21654
[Other specifications]
ff1 53.4659
ff2 71.94709
MVF1w -0.4718
MVF2w 0.42473

14 (A), 14 (B), and 14 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fifth embodiment, respectively. It is a diagram of various aberrations of. 15 (A), 15 (B), and 15 (C) show the wide-angle end state, the intermediate focal length state, and the telephoto end state of the variable magnification optical system according to the fifth embodiment, respectively, at the time of short-distance focusing. It is a diagram of various aberrations of. From each aberration diagram, the variable magnification optical system according to the fifth embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance, and further, at the time of short-distance focusing. It can be seen that also has excellent imaging performance.

Finally, the table of [Conditional expression correspondence value] is shown below. In this table, the values corresponding to each conditional expression (1) to (5) are summarized for all the examples (first to fifth examples).
Conditional expression (1) 0.10 <(-f1) /f2 <1.20
Conditional expression (2) 0.20 <ff1 / ff2 <1.70
Conditional expression (3) 0.15 <(-f1) / ff1 <1.30
Conditional expression (4) 0.10 <(-f1) / ff2 <0.95
Conditional expression (5) 0.01 <(-MVF1) / MVF2 <30.0
Conditional expression (6) −0.80 <βWF1 <0.80
Conditional expression (7) −0.80 <βWF2 <0.80
Conditional expression (8) (βWF1 + (1 / βWF1)) ^-2 <0.25
Conditional expression (9) (βWF2 + (1 / βWF2)) ^-2 <0.25

[Conditional expression correspondence value]
Conditional expression 1st Example 2nd Example 3rd Example 4th Example 5th Example (1) 0.442 0.778 0.667 0.400 1.111
(2) 0.454 0.593 0.953 0.569 0.743
(3) 0.615 0.399 0.508 0.614 0.386
(4) 0.279 0.237 0.484 0.349 0.287
(5) 0.368 0.493 0.590 0.680 -0.199
(6) 0.185 0.422 0.432 -0.298 0.524
(7) 0.374 0.480 0.115 -0.671 0.460
(8) 0.032 0.128 0.132 0.075 0.169
(9) 0.108 0.152 0.013 0.214 0.144

The first to fifth embodiments described above show a specific example of the present embodiment, and the present embodiment is not limited thereto.

The following contents can be appropriately adopted as long as the optical performance of the variable magnification optical system according to the present embodiment is not impaired.

As numerical examples of the variable magnification optical system, those having a 4-group configuration, a 5-group configuration, a 6-group configuration, and a 7-group configuration are shown, but the present application is not limited to this, and other group configurations (for example, 8 groups, etc.) are shown. A variable magnification optical system can also be configured. Specifically, a lens or a lens group may be added to the most object side or the most image plane side of the variable magnification optical system. The lens group refers to a portion having at least one lens separated by an air interval that changes at the time of magnification change.

The lens surface may be formed on a spherical surface or a flat surface, or may be formed on an aspherical surface. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to processing and assembly adjustment errors can be prevented, which is preferable. Further, even if the image plane is deviated, the depiction performance is less deteriorated, which is preferable.

When the lens surface is aspherical, the aspherical surface is an aspherical surface formed by grinding, a glass mold aspherical surface formed by forming glass into an aspherical shape, or a composite aspherical surface formed by forming resin on the glass surface into an aspherical shape. It doesn't matter which one. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

The role of the aperture diaphragm may be substituted by the frame of the lens without providing the member as the aperture diaphragm.

An antireflection film having a high transmittance in a wide wavelength range may be applied to each lens surface in order to reduce flare and ghost and achieve high contrast optical performance. As a result, flare and ghost can be reduced, and high-contrast and high optical performance can be achieved.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group I image plane S aperture aperture

Claims (17)

It has a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a succeeding lens group arranged side by side on the optical axis in order from the object side.
When scaling from the wide-angle end to the telephoto end, the distance between adjacent lens groups changes,
The subsequent lens group includes a first focusing lens group having a positive refractive power and a second focusing lens group having a positive refractive power.
A variable magnification optical system in which the first focusing lens group and the second focusing lens group move in the optical axis direction when focusing from infinity to a short distance. The variable magnification optical system according to claim 1, which satisfies the following conditional expression.
0.10 <(-f1) /f2 <1.20
However, f1: the focal length of the first lens group,
f2: Focal length of the second lens group The variable magnification optical system according to claim 1 or 2, which satisfies the following conditional expression 0.20 <ff1 / ff2 <1.70
However, ff1: focal length of the first focusing lens group ff2: focal length of the second focusing lens group The variable magnification optical system according to any one of claims 1 to 3, which satisfies the following conditional expression.
0.15 <(-f1) / ff1 <1.30 The variable magnification optical system according to any one of claims 1 to 4, which satisfies the following conditional expression.
0.10 <(-f1) / ff2 <0.95 The variable magnification optical system according to any one of claims 1 to 5, wherein the first focusing lens group moves to the object side when the magnification is changed from infinity to close proximity. The variable magnification optical system according to any one of claims 1 to 6, wherein the second focusing lens group moves to the image side when the magnification is changed from infinity to close proximity. The variable magnification optical system according to any one of claims 1 to 7, which satisfies the following conditional expression 0.01 <(-MVF1) / MVF2 <30.00.
However, MVF1: the amount of movement of the first focusing lens group when focusing from an infinite object to a short-distance object,
MVF2: The amount of movement of the second focusing lens group when focusing from an infinite object to a short-distance object,
The movement to the image side is positive. The variable magnification optical system according to any one of claims 1 to 8, wherein the second focusing lens group comprises one convex lens. The variable magnification optical system according to any one of claims 1 to 9, wherein the first focusing lens group includes a junction lens of a convex lens and a concave lens. The variable magnification optical system according to any one of claims 1 to 10, wherein the first lens group has three negative lenses in order from the object side. The variable magnification optical system according to any one of claims 1 to 11, which satisfies the following conditional expression.
−0.80 <βWF1 <0.80
However, βWF1: the lateral magnification of the first focusing lens group at the time of focusing an object at infinity in the wide-angle end state. The variable magnification optical system according to any one of claims 1 to 12, which satisfies the following conditional expression.
−0.80 <βWF2 <0.80
However, βWF2; the lateral magnification of the second focusing lens group at the time of focusing an object at infinity in the wide-angle end state. The variable magnification optical system according to any one of claims 1 to 13, which satisfies the following conditional expression.
(ΒWF1 + (1 / βWF1)) ^-2 <0.25
However, βWF1: the lateral magnification of the first focusing lens group at the time of focusing an object at infinity in the wide-angle end state. The variable magnification optical system according to any one of claims 1 to 14, which satisfies the following conditional expression.
(ΒWF2 + (1 / βWF2)) ^-2 <0.25
However, βWF2: lateral magnification at the time of focusing on an infinite object in the wide-angle end state of the second focusing lens group. An optical device including the variable magnification optical system according to any one of claims 1 to 15. The following lens group has a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a succeeding lens group arranged side by side on the optical axis in order from the object side. Is a method for manufacturing a variable magnification optical system having a first focusing lens group having a positive refractive power and a second focusing lens group having a positive refractive power.
When scaling from the wide-angle end to the telephoto end, the distance between adjacent lens groups changes,
When focusing from infinity to a short distance, the first focusing lens group and the second focusing lens group move in the optical axis direction.
A method for manufacturing a variable magnification optical system in which each lens is arranged in a lens barrel.

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