Variable magnification optical system and imaging device

Abstract

The present invention provides a variable magnification optical system that achieves compactness, wide angle, and high magnification ratio while possessing good optical performance, as well as an imaging device equipped with this variable magnification optical system. [Solution] The variable magnification optical system consists of a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group, and a final lens group with positive refractive power, arranged in order from the object side to the image side. The front intermediate lens group with positive refractive power is positioned closest to the object in the intermediate group, and the rear intermediate lens group with negative refractive power is positioned closest to the image in the intermediate group. When magnification is changed from the wide-angle end to the telephoto end, the first lens group moves toward the object side. When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, the variable magnification optical system is -0.25

Description

Technical Field

[0001] The technology of the present disclosure relates to a zoom optical system and an imaging device.

Background Art

[0002] Conventionally, as an optical system applicable to an imaging device such as a digital camera, the optical system described in Patent Document 1 below has been proposed.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for a zoom optical system that is small in size, has a high zoom ratio, and has good optical performance. Furthermore, wide-angle conversion is also demanded. These required levels are increasing year by year.

[0005] The present disclosure provides a zoom optical system having good optical performance while achieving small size, wide angle, and high zoom ratio, and an imaging device including this zoom optical system.

Means for Solving the Problems

[0006] The zoom optical system according to one aspect of the present disclosure includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group composed of a plurality of lens groups, and a final lens group having a positive refractive power. A front intermediate lens group having a positive refractive power is disposed on the most object side of the intermediate group, and a rear intermediate lens group having a negative refractive power is disposed on the most image side of the intermediate group. When zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, and all the intervals between adjacent lens groups change. -0.25 < f2 / f1 < -0.05 (1) The condition (1) expressed by is satisfied. Here, the focal length of the first lens group is set to f1. The focal length of the second lens group is set to f2.

[0007] The first lens group preferably consists of a negative meniscus lens with a convex surface on the object side, a positive lens, and another positive lens, in order from the object side to the image side.

[0008] It is preferable to place a positive lens, whose image-side surface is convex, at the image-side end of the final lens group.

[0009] If ZDD1 is defined as the difference between the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane at the wide-angle end and the distance along the optical axis from the lens surface closest to the object in the first lens group to the image plane at the telephoto end, and fw is the focal length of the variable magnification optical system at the wide-angle end, then the variable magnification optical system of the above embodiment is: 2 <ZDD1 / fw<15 (2) It is preferable that the condition (2) expressed by is satisfied.

[0010] In a configuration where a negative meniscus lens, whose object-side surface is convex, is positioned on the object-side side of the first lens group, if the refractive index of the negative meniscus lens on the object-side side of the first lens group with respect to the d-line is Nd1, then the variable magnification optical system of the above embodiment is: 1.7 <Nd1<2.4 (3) It is preferable that the condition expressed in equation (3) is satisfied.

[0011] If the refractive index of the positive lens on the image side of the final lens group with respect to the d line is NdEr, then the variable magnification optical system of the above embodiment is: 1.43 <NdEr<1.85 (4) It is preferable that the condition expressed in equation (4) is satisfied.

[0012] When the distance on the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the final lens group at the wide-angle end, and the sum of the back focus at the air-equivalent distance of the zoom optical system is defined as TLw, and the back focus at the air-equivalent distance of the zoom optical system at the wide-angle end is defined as Bfw, the zoom optical system of the above aspect is 4 < TLw / Bfw < 12 (5) Preferably satisfies the conditional expression (5) represented by

[0013] When the distance on the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the final lens group at the telephoto end, and the sum of the back focus at the air-equivalent distance of the zoom optical system is defined as TLt, and the focal length of the zoom optical system at the telephoto end is defined as ft, the zoom optical system of the above aspect is 0.85 < TLt / ft < 3 (6) Preferably satisfies the conditional expression (6) represented by

[0014] When the focal length of the final lens group is defined as fE, the zoom optical system of the above aspect is 0.9 < f1 / fE < 3 (7) Preferably satisfies the conditional expression (7) represented by

[0015] When the distance on the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the final lens group at the wide-angle end, and the sum of the back focus at the air-equivalent distance of the zoom optical system is defined as TLw, and the focal length of the zoom optical system at the wide-angle end is defined as fw, the zoom optical system of the above aspect is 6 < TLw / fw < 10 (8) Preferably satisfies the conditional expression (8) represented by

[0016] When the refractive index with respect to the d line of the positive lens closest to the object side among the positive lenses included in the first lens group is defined as Nd1p, the zoom optical system of the above aspect is 1.43 < Nd1p < 1.72 (9) Preferably satisfies the conditional expression (9) represented by

[0017] The positive lens closest to the image side of the final lens group is preferably a meniscus lens.

[0018] During zooming, the final lens group may be configured to be fixed with respect to the image plane.

[0019] When the focal length of the rear intermediate lens group is fMr and the focal length of the final lens group is fE, the zoom optical system of the above aspect is -1.5 < fMr / fE < -0.1 (10) It is preferable to satisfy the conditional expression (10) represented by

[0020] When the back focus at the air equivalent distance of the zoom optical system at the wide-angle end is Bfw and the focal length of the zoom optical system at the wide-angle end is fw, the zoom optical system of the above aspect is 0.8 < Bfw / fw < 2 (11) It is preferable to satisfy the conditional expression (11) represented by

[0021] When the focal length of the zoom optical system at the telephoto end is ft and the focal length of the zoom optical system at the wide-angle end is fw, the zoom optical system of the above aspect is 4 < ft / fw < 30 (12) It is preferable to satisfy the conditional expression (12) represented by

[0022] When the focal length of the front intermediate lens group is fMf, the zoom optical system of the above aspect is -3 < fMf / f2 < -0.7 (13) It is preferable to satisfy the conditional expression (13) represented by

[0023] When the combined lateral magnification of all the groups on the image side of the second lens group in the state of focusing on an infinite object at the telephoto end is βT2R and the combined lateral magnification of all the groups on the image side of the second lens group in the state of focusing on an infinite object at the wide-angle end is βW2R, the zoom optical system of the above aspect is 1.5 < βT2R / βW2R < 5 (14) It is preferable to satisfy the conditional expression (14) represented by

[0024] When the lateral magnification of the second lens group is βT2 when focused on an object at infinity at the telephoto end, and the lateral magnification of the second lens group is βW2 when focused on an object at infinity at the wide-angle end, the variable magnification optical system of the above embodiment is: 1.5 < βT2 / βW2 < 6 (15) It is preferable that the conditional expression (15) represented by is satisfied.

[0025] Another aspect of the present disclosure is an imaging device equipped with the magnification optical system of the above aspect.

[0026] Furthermore, the terms "~consisting of" and "~consisting of" in this specification are intended to include, in addition to the listed components, lenses that substantially have no refractive power, optical elements other than lenses such as apertures, filters, and cover glass, and mechanical parts such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.

[0027] In this specification, "a group of lenses having positive refractive power" means that the group as a whole has positive refractive power. Similarly, "a group of lenses having negative refractive power" means that the group as a whole has negative refractive power. "A lens having positive refractive power" and "a positive lens" are synonymous. "A lens having negative refractive power" and "a negative lens" are synonymous. In this specification, "a group of lenses," "a lens group," and "a focusing group" are not limited to a configuration consisting of multiple lenses, but may also consist of a single lens.

[0028] In this specification, the number of lenses refers to the number of constituent lenses. For example, in a cemented lens formed by joining multiple single lenses of different materials, the number of lenses is expressed as the number of single lenses that make up the cemented lens. However, a composite aspherical lens (i.e., a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on that lens are integrally constructed and function as a single aspherical lens as a whole) is not considered a cemented lens and is treated as a single lens. Unless otherwise specified, the sign of the refractive power and the surface shape for lenses including aspherical surfaces are those of the paraxial region.

[0029] In this specification, the "focal length" used in the conditional equations refers to the paraxial focal length. Unless otherwise specified, the "distance on the optical axis" used in the conditional equations refers to the geometric distance. Unless otherwise specified, the values ​​used in the conditional equations are those obtained when the image is in focus on an object at infinity, with the d-line as the reference.

[0030] The terms "d-line," "C-line," "F-line," and "g-line" used herein are emission lines. The wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), the wavelength of the F-line as 486.13 nm (nanometers), and the wavelength of the g-line as 435.84 nm (nanometers). [Effects of the Invention]

[0031] According to this disclosure, it is possible to provide a variable magnification optical system that has good optical performance while achieving compactness, wide angle, and high magnification ratio, as well as an imaging device equipped with this variable magnification optical system. [Brief explanation of the drawing]

[0032] [Figure 1] This figure corresponds to the variable magnification optical system of Example 1 and shows a cross-sectional view and movement trajectory of the configuration of the variable magnification optical system according to one embodiment. [Figure 2] Figure 1 is a cross-sectional view of the configuration of the variable magnification optical system, and is also a diagram for explaining the notation of the conditional equation. [Figure 3] These are aberration diagrams for the variable magnification optical system of Example 1. [Figure 4] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 2. [Figure 5] These are aberration diagrams for the variable magnification optical system of Example 2. [Figure 6] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 3. [Figure 7] These are aberration diagrams for the variable magnification optical system of Example 3. [Figure 8] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 4. [Figure 9] These are aberration diagrams for the variable magnification optical system of Example 4. [Figure 10] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 5. [Figure 11] These are aberration diagrams for the variable magnification optical system of Example 5. [Figure 12] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 6. [Figure 13] These are aberration diagrams for the variable magnification optical system of Example 6. [Figure 14] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 7. [Figure 15] These are aberration diagrams for the variable magnification optical system of Example 7. [Figure 16] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 8. [Figure 17] These are aberration diagrams for the variable magnification optical system of Example 8. [Figure 18] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 9. [Figure 19] These are aberration diagrams for the variable magnification optical system of Example 9. [Figure 20] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 10. [Figure 21] These are aberration diagrams for the variable magnification optical system of Example 10. [Figure 22] This figure shows a cross-sectional view and movement trajectory of the variable magnification optical system configuration of Example 11. [Figure 23] These are aberration diagrams for the variable magnification optical system of Example 11. [Figure 24] This is a front perspective view of an imaging device according to one embodiment. [Figure 25] Figure 24 is a perspective view of the rear side of the imaging device shown. [Modes for carrying out the invention]

[0033] Embodiments of this disclosure will be described below with reference to the drawings.

[0034] Figure 1 shows the configuration of a variable magnification optical system, a cross-sectional view of the light beam, and the movement trajectory according to one embodiment of the present disclosure. In Figure 1, the light beams shown are the on-axial light beam and the light beam with the maximum half-angle of view ωw at the wide-angle end, and the on-axial light beam and the light beam with the maximum half-angle of view ωt at the telephoto end. Figure 2 shows a cross-sectional view of the configuration of the variable magnification optical system of Figure 1. In Figures 1 and 2, the upper section labeled "Wide" shows the wide-angle end state, and the lower section labeled "Tele" shows the telephoto end state. In Figures 1 and 2, the left side is the object side and the right side is the image side, showing the state when focused on an object at infinity. The examples shown in Figures 1 and 2 correspond to the variable magnification optical system of Embodiment 1 described later. The following explanation will mainly refer to Figure 1, and to Figure 2 as necessary.

[0035] Figure 1 shows an example where a parallel plate-shaped optical element PP is placed between the variable magnification optical system and the image plane Sim, assuming that the variable magnification optical system is applied to an imaging device. The optical element PP is a component that is intended to be various filters and / or cover glass. The various filters include low-pass filters, infrared cut filters, and / or filters that cut out a specific wavelength range. The optical element PP is a component that does not have refractive power. It is also possible to configure the imaging device without the optical element PP.

[0036] The variable magnification optical system of this disclosure consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM consisting of multiple lens groups, and a final lens group GE having positive refractive power, arranged in order from the object side to the image side along the optical axis Z. The front intermediate lens group having positive refractive power is positioned closest to the object side of the intermediate group GM. The rear intermediate lens group having negative refractive power is positioned closest to the image side of the intermediate group GM. When magnification is changed from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the spacing between all adjacent lens groups changes.

[0037] By making the first lens group G1, which is closest to the object, a lens group with positive refractive power, the overall length can be shortened, which is advantageous for achieving both miniaturization and a high magnification ratio. Also, by making the refractive power of the first lens group G1 positive, the height of the incident light rays to the second lens group G2 can be lowered, which is advantageous for suppressing aberration fluctuations during magnification. By arranging the second lens group G2, which has negative refractive power, it is advantageous for wide-angle viewing. By arranging the front intermediate lens group with positive refractive power adjacent to the image side of the second lens group G2, it is advantageous for miniaturization. The intermediate group GM includes both positive and negative lens groups, a front intermediate lens group with positive refractive power and a rear intermediate lens group with negative refractive power, which is advantageous for correcting various aberrations. By making the refractive power of the final lens group GE, which is closest to the image, the incident angle of the off-axis principal rays to the image plane Sim can be made smaller. During magnification, the first lens group G1 moves towards the object side, which is advantageous for achieving a high magnification ratio. Furthermore, the change in the spacing between multiple lens groups during magnification is advantageous in suppressing various aberrations across the entire magnification range.

[0038] In this specification, a group of lenses whose distance in the optical axis direction changes when magnification is varied is defined as one lens group. Within a single lens group, the distance between adjacent lenses does not change when magnification is varied. That is, a "lens group" is a component of a variable magnification optical system that includes at least one lens, separated by the air gap that changes when magnification is varied. When magnification is varied, each lens group is moved or fixed. A "lens group" may include components other than lenses that do not have refractive power, such as an aperture diaphragm St.

[0039] As an example, the variable magnification optical system in Figure 1 consists of, in order from the object side to the image side, the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5. In the example in Figure 1, the intermediate group GM consists of the third lens group G3 and the fourth lens group G4, and the final lens group GE consists of the fifth lens group G5. In the example in Figure 1, the front intermediate lens group corresponds to the third lens group G3, and the rear intermediate lens group corresponds to the fourth lens group G4. Note that, to avoid complexity in the diagram, some reference numerals are omitted in the lower part of Figure 1.

[0040] As an example, each group of the variable magnification optical system in Figure 1 is configured as follows, as shown in Figure 2. The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture diaphragm St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51. The aperture diaphragm St shown in Figures 1 and 2 indicates its position in the optical axis direction, not its size or shape.

[0041] In the example in Figure 1, during magnification, the fifth lens group G5 is fixed relative to the image plane Sim, while the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z by changing the spacing between adjacent lens groups. In Figure 1, between the upper and lower diagrams, the approximate movement trajectories of each lens group during magnification, from the wide-angle end to the telephoto end, are shown by solid arrows.

[0042] Note that the example in Figure 1 is just one example, and the variable magnification optical system of this disclosure can be modified in various ways without departing from the spirit of the technology of this disclosure. For example, the number of lens groups included in the intermediate group GM may differ from the example in Figure 1. The number and configuration of lenses included in each lens group may differ from the example in Figure 1. The behavior of each lens group during magnification may differ from the example in Figure 1. Also, although Figure 1 shows an example where the variable magnification optical system is a zoom lens, the variable magnification optical system of this disclosure may be a varifocal lens.

[0043] It is preferable to place a negative meniscus lens, whose object-side surface is convex, at the object-side end of the first lens group G1. Placing a negative meniscus lens with a convex object-side surface at the object-side end facilitates aberration correction when the focal length of the variable magnification optical system is shortened at the wide-angle end. The first lens group G1 may also be configured to consist of a negative meniscus lens with a convex object-side surface, a positive lens, and a positive lens, in order from the object side to the image side. In this case, aberration correction within the first lens group G1 becomes easier, which is advantageous in suppressing aberration fluctuations during magnification. Furthermore, the above-mentioned effect can be obtained by placing a negative meniscus lens with a convex object-side surface at the object-side end.

[0044] The second lens group G2 may be configured, for example, to consist of three negative lenses and one positive lens. The second lens group G2 may be configured so that the negative lens is located on the image side, in which case the negative lens on the image side of the second lens group G2 may be a meniscus lens with a convex surface on the image side.

[0045] The intermediate lens group GM may be configured to consist of a front intermediate lens group and a rear intermediate lens group, as shown in the example in Figure 1. By configuring the intermediate lens group GM to consist of two lens groups, the lens group drive mechanism can be simplified.

[0046] Alternatively, the intermediate GM group may be configured to consist of a front intermediate lens group, a lens group with positive refractive power, and a rear intermediate lens group. Configuring the intermediate GM group to consist of three lens groups in this way is advantageous in suppressing aberration fluctuations during magnification. Furthermore, since the positive refractive power can be shared, it is particularly advantageous for achieving high magnification ratios.

[0047] If the intermediate lens group GM consists of a front intermediate lens group, a lens group with positive refractive power, and a rear intermediate lens group, the final lens group GE may be configured to move during magnification. By configuring the intermediate lens group GM to consist of three lens groups, the above effect can be obtained, and furthermore, by making the final lens group GE movable during magnification, it is advantageous to suppress aberration fluctuations during magnification.

[0048] The intermediate GM group may be configured to consist of a front intermediate lens group, a lens group with negative refractive power, and a rear intermediate lens group. Configuring the intermediate GM group to consist of three lens groups in this way is advantageous in suppressing aberration fluctuations during magnification. Furthermore, it becomes easier to increase the positive refractive power of the front intermediate lens group, which is advantageous in securing back focus when widening the angle.

[0049] The intermediate lens group GM may be configured so that the aperture diaphragm St is positioned closest to the object. In this case, the distance between the first lens group G1 and the aperture diaphragm St can be made relatively short, thus shortening the distance from the lens surface closest to the object to the entrance pupil position, which is advantageous for miniaturizing the first lens group G1.

[0050] The rear intermediate lens group may be configured to consist of a single negative lens. This configuration is advantageous for reducing the weight of the optical system.

[0051] Alternatively, the rear intermediate lens group may be configured to consist of a single cemented lens formed by joining a positive lens and a negative lens. This configuration is advantageous in suppressing fluctuations in chromatic aberration during magnification.

[0052] The rear intermediate lens group may be configured so that the positive lens is positioned closest to the object. This configuration is advantageous for correcting spherical aberration at the telephoto end.

[0053] The rear intermediate lens group may be configured so that the negative lens is positioned closest to the image sensor. This configuration is advantageous for correcting field curvature.

[0054] It is preferable to place a positive lens, whose image-side surface is convex, at the image-side end of the final lens group GE. In this case, aberration correction within the final lens group GE is easier, which is advantageous in suppressing aberration fluctuations during magnification. It is preferable that the positive lens at the image-side end of the final lens group GE is a meniscus lens. In this case, aberration correction within the final lens group GE is even easier, which is advantageous in suppressing aberration fluctuations during magnification.

[0055] The final lens group GE may be configured to consist of one or two lenses. This configuration is advantageous for miniaturization.

[0056] The final lens group GE may be configured to consist of positive lenses, where the image-side surface in the paraxial region is convex and at least one lens surface has an aspherical shape. Configuring the final lens group GE with such aspherical lenses is advantageous for suppressing aberrations and simplifies the configuration of the final lens group GE.

[0057] During magnification, the final lens group GE may be configured to be fixed to the image plane Sim. In this case, the lens drive mechanism can be simplified.

[0058] Alternatively, the final lens group GE may be configured to move during magnification. This configuration is advantageous in suppressing aberration fluctuations during magnification.

[0059] The variable magnification optical system may be configured to include a focusing group that moves along the optical axis Z when focusing. Typically, the amount of movement of the focusing group when focusing is greater at the telephoto end than at the wide-angle end. Also, in the lens group configuration of the variable magnification optical system of this disclosure, the gap between the rear intermediate lens group and the final lens group GE tends to widen considerably. For these reasons, in order to ensure sufficient spacing for the focusing group to move, it is preferable to configure the focusing group to consist of the rear intermediate lens group. Furthermore, it is preferable that the rear intermediate lens group moves toward the image side when focusing from an object at infinity to a nearby object. By configuring it in this way, the focusing group can be miniaturized, which is advantageous for miniaturizing the entire lens system and also advantageous for suppressing breathing. If, in a lens group configuration similar to the variable magnification optical system of this disclosure, the focusing group is composed of a lens group other than the rear intermediate lens group, it is necessary to widen the spacing between the lens groups in order to focus, which may be disadvantageous for miniaturizing the entire lens system.

[0060] In the example shown in Figure 1, the focusing group consists of the fourth lens group G4, which is the rear intermediate lens group. In the lower part of Figure 1, parentheses and left-right arrows are placed below the lenses corresponding to the focusing group. These left-right arrows indicate the direction in which the focusing group moves when focusing from an object at infinity to a nearby object. The focusing group functions throughout the entire zoom range, including the wide-angle end, but in Figure 1, to avoid complexity, the arrows are only shown in the lower part of the diagram. The same method of illustrating the focusing group is used in the diagrams of other embodiments.

[0061] In the variable magnification optical system of this disclosure, it is preferable that the maximum full angle of view at the wide-angle end is 80 degrees or more. In this case, a variable magnification optical system with a larger angle of view at the wide-angle end can be realized. The maximum full angle of view is twice the maximum half angle of view. It is more preferable that the maximum full angle of view at the wide-angle end be 85 degrees or more, even more preferably 90 degrees or more, and even more preferably 95 degrees or more.

[0062] Next, preferred configurations of the variable magnification optical system of this disclosure with respect to the conditional formulas will be described. In the following explanation of the conditional formulas, the same symbols will be used for the same definitions, and redundant explanations of symbols will be omitted to avoid redundancy. Also, to avoid redundancy, "the variable magnification optical system of this disclosure" will also be simply referred to as "the variable magnification optical system" below.

[0063] When the focal length of the first lens group G1 is f1 and the focal length of the second lens group G2 is f2, it is preferable that the variable magnification optical system satisfies the following condition (1). By ensuring that the corresponding value in condition (1) does not fall below the lower limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous in suppressing aberrations occurring in the first lens group G1, especially spherical aberration at the telephoto end. By ensuring that the corresponding value in condition (1) does not exceed the upper limit, the refractive power of the first lens group G1 does not become too weak, which allows the height of the light rays incident on the second lens group G2 to be lowered, thereby being advantageous in miniaturizing the optical system. -0.25 <f2 / f1<-0.05 (1)

[0064] To obtain better characteristics, the lower limit of conditional equation (1) is more preferably -0.22, even more preferably -0.2, even more preferably -0.18, even more preferably -0.17, even more preferably -0.16, and even more preferably -0.15. To obtain better characteristics, the upper limit of conditional equation (1) is more preferably -0.07, even more preferably -0.09, even more preferably -0.1, even more preferably -0.115, even more preferably -0.12, and even more preferably -0.125.

[0065] The variable magnification optical system preferably satisfies the following condition (2). Here, ZDD1 is defined as the difference between the distance along the optical axis from the lens surface closest to the object of the first lens group G1 to the image plane Sim at the wide-angle end and the distance along the optical axis from the lens surface closest to the object of the first lens group G1 to the image plane Sim at the telephoto end. fw is the focal length of the variable magnification optical system at the wide-angle end. As an example, Figure 2 shows the above difference ZDD1. Note that since the variable magnification optical system shown in Figures 1 and 2 is a zoom lens, the position of the image plane Sim does not change even when magnification is applied, as shown in Figure 2. By ensuring that the corresponding value of condition (2) does not fall below the lower limit, it is advantageous to achieve both wide-angle and high magnification ratios. By ensuring that the corresponding value of condition (2) does not exceed the upper limit, the amount of movement of the first lens group G1 during magnification can be reduced, which is advantageous for miniaturizing the optical system. 2 <ZDD1 / fw<15 (2)

[0066] To obtain better characteristics, the lower limit of conditional equation (2) is more preferably 2.4, even more preferably 2.7, even more preferably 3, even more preferably 3.1, even more preferably 3.2, and even more preferably 3.3. To obtain better characteristics, the upper limit of conditional equation (2) is more preferably 13, even more preferably 11, even more preferably 10, even more preferably 9, even more preferably 8, and even more preferably 7.5.

[0067] In a configuration where a negative meniscus lens, whose object-facing surface is convex, is positioned on the object-facing side of the first lens group G1, it is preferable that the variable magnification optical system satisfies the following condition (3). Here, Nd1 is defined as the refractive index of the negative meniscus lens on the object-facing side of the first lens group G1 with respect to the d line. By ensuring that the corresponding value in condition (3) does not fall below the lower limit, it is advantageous to suppress aberrations occurring in the first lens group G1, particularly spherical aberration at the telephoto end and astigmatism at the wide-angle end. By ensuring that the corresponding value in condition (3) does not exceed the upper limit, it is possible to select a material with high transmittance. 1.7 <Nd1<2.4 (3)

[0068] To obtain better characteristics, the lower limit of conditional equation (3) is more preferably 1.8, even more preferably 1.85, even more preferably 1.88, even more preferably 1.9, even more preferably 1.91, and even more preferably 1.92. To obtain better characteristics, the upper limit of conditional equation (3) is more preferably 2.35, even more preferably 2.3, even more preferably 2.2, even more preferably 2.15, even more preferably 2.1, and even more preferably 2.06.

[0069] In a configuration where a positive lens with a convex image-side surface is positioned on the image-side end of the final lens group GE, it is preferable that the variable magnification optical system satisfies the following condition (4). Here, NdEr is defined as the refractive index of the positive lens on the image-side end of the final lens group GE with respect to the d line. By ensuring that the corresponding value in condition (4) does not fall below the lower limit, it becomes easier to secure the refractive power required for the final lens group GE, which is advantageous for suppressing aberrations occurring in the final lens group GE. By ensuring that the corresponding value in condition (4) does not exceed the upper limit, the refractive power of the final lens group GE does not become too strong, which is advantageous for correcting field curvature and distortion aberrations. 1.43 <NdEr<1.85 (4)

[0070] To obtain better characteristics, the lower limit of conditional equation (4) is more preferably 1.46, even more preferably 1.47, even more preferably 1.48, even more preferably 1.49, and even more preferably 1.5. To obtain better characteristics, the upper limit of conditional equation (4) is more preferably 1.75, even more preferably 1.7, even more preferably 1.65, even more preferably 1.62, and even more preferably 1.6.

[0071] The variable magnification optical system preferably satisfies the following condition (5). Here, TLw is the sum of the distance along the optical axis from the lens surface closest to the object of the first lens group G1 to the lens surface closest to the image of the final lens group GE at the wide-angle end, and the back focus of the variable magnification optical system in air equivalent distance. Bfw is the back focus of the variable magnification optical system in air equivalent distance at the wide-angle end. By ensuring that the corresponding value of condition (5) does not fall below the lower limit, the back focus is shortened, allowing the final lens group GE to be positioned further away from the other lens groups, which is advantageous for correcting field curvature. By ensuring that the corresponding value of condition (5) does not exceed the upper limit, it is advantageous for miniaturizing the optical system at the wide-angle end and for securing the back focus. 4 <TLw / Bfw<12 (5)

[0072] To obtain better characteristics, the lower limit of conditional equation (5) is more preferably set to 4.2, and even more preferably to 4.8. To obtain better characteristics, the upper limit of conditional equation (5) is more preferably set to 11, and even more preferably to 10.

[0073] The variable magnification optical system preferably satisfies the following condition (6). Here, TLt is the sum of the distance along the optical axis from the object-side lens surface of the first lens group G1 to the image-side lens surface of the final lens group GE at the telephoto end, and the back focus of the variable magnification optical system in air equivalent distance. ft is the focal length of the variable magnification optical system at the telephoto end. Ensuring that the corresponding value in condition (6) does not fall below the lower limit is advantageous for aberration correction at the telephoto end. Ensuring that the corresponding value in condition (6) does not exceed the upper limit is advantageous for miniaturizing the optical system at the telephoto end. 0.85 <TLt / ft<3 (6)

[0074] To obtain better characteristics, the lower limit of conditional equation (6) is more preferably 0.89, and even more preferably 0.92. To obtain better characteristics, the upper limit of conditional equation (6) is more preferably 2.5, and even more preferably 2.3.

[0075] When the focal length of the final lens group GE is fE, it is preferable that the variable magnification optical system satisfies the following condition (7). By ensuring that the corresponding value in condition (7) does not fall below the lower limit, the refractive power of the first lens group G1 does not become too strong, which is advantageous in suppressing aberrations occurring in the first lens group G1, especially spherical aberration at the telephoto end. By ensuring that the corresponding value in condition (7) does not exceed the upper limit, the refractive power of the first lens group G1 does not become too weak, which allows the height of the light rays incident on the second lens group G2 to be lowered, thereby being advantageous in miniaturizing the optical system. 0.9 <f1 / fE<3 (7)

[0076] To obtain better characteristics, the lower limit of conditional equation (7) is more preferably 1, even more preferably 1.05, even more preferably 1.1, even more preferably 1.13, and even more preferably 1.15. To obtain better characteristics, the upper limit of conditional equation (7) is more preferably 2.5, even more preferably 2.2, even more preferably 1.9, even more preferably 1.7, and even more preferably 1.5.

[0077] The variable magnification optical system preferably satisfies the following condition (8). Ensuring that the corresponding value in condition (8) does not fall below the lower limit is advantageous for achieving a high magnification ratio. Ensuring that the corresponding value in condition (8) does not exceed the upper limit is advantageous for miniaturizing the optical system at the wide-angle end. 6 <TLw / fw<10 (8)

[0078] To obtain better characteristics, the lower limit of conditional equation (8) is more preferably 6.5, and even more preferably 7. To obtain better characteristics, the upper limit of conditional equation (8) is more preferably 9.9, and even more preferably 9.7.

[0079] The variable magnification optical system preferably satisfies the following condition (9). Here, Nd1p is defined as the refractive index with respect to the d line of the positive lens closest to the object among the positive lenses included in the first lens group G1. By ensuring that the corresponding value in condition (9) does not fall below the lower limit, it is advantageous to suppress spherical aberration, especially at the telephoto end, and astigmatism at the wide-angle end. Generally, as the refractive index decreases, the specific gravity decreases, so by ensuring that the corresponding value in condition (9) does not exceed the upper limit, it is advantageous to reduce the weight of the lens. Furthermore, by ensuring that the corresponding value in condition (9) does not exceed the upper limit, it becomes easier to select materials with a large Abbe number, which is advantageous to suppress chromatic aberration. 1.43 <Nd1p<1.72 (9)

[0080] To obtain better characteristics, the lower limit of conditional equation (9) is more preferably 1.48, even more preferably 1.5, even more preferably 1.52, and even more preferably 1.54. To obtain better characteristics, the upper limit of conditional equation (9) is more preferably 1.68, even more preferably 1.65, even more preferably 1.62, and even more preferably 1.6.

[0081] When the focal length of the rear intermediate lens group is fMr, it is preferable that the variable magnification optical system satisfies the following condition (10). By ensuring that the corresponding value in condition (10) does not fall below the lower limit, the refractive power of the final lens group GE does not become too strong, making it easier to correct aberrations within the final lens group GE, which is advantageous in suppressing aberration fluctuations during magnification. By ensuring that the corresponding value in condition (10) does not exceed the upper limit, the refractive power of the final lens group GE does not become too weak, which is advantageous in correcting field curvature and distortion aberrations. -1.5 <fMr / fE<-0.1 (10)

[0082] To obtain better characteristics, the lower limit of conditional equation (10) is more preferably -1.2, even more preferably -0.9, even more preferably -0.6, even more preferably -0.5, and even more preferably -0.4. To obtain better characteristics, the upper limit of conditional equation (10) is more preferably -0.2, even more preferably -0.22, even more preferably -0.24, even more preferably -0.26, and even more preferably -0.27.

[0083] The variable magnification optical system preferably satisfies the following condition (11). By ensuring that the corresponding value in condition (11) does not fall below the lower limit, it is advantageous to secure back focus and also advantageous to widen the angle of view. By ensuring that the corresponding value in condition (11) does not exceed the upper limit, the back focus is shortened, so that the final lens group GE can be placed at a position away from the other lens groups, which is advantageous for correcting field curvature. 0.8 <Bfw / fw<2 (11)

[0084] To obtain better characteristics, the lower limit of conditional equation (11) is more preferably 0.85, and even more preferably 0.87. To obtain better characteristics, the upper limit of conditional equation (11) is more preferably 1.98, and even more preferably 1.95.

[0085] The variable magnification optical system preferably satisfies the following condition (12). By ensuring that the corresponding value in condition (12) does not fall below the lower limit, a variable magnification optical system with a higher magnification ratio can be realized. By not making the magnification ratio too high so that the corresponding value in condition (12) does not exceed the upper limit, it is advantageous for miniaturization and suppression of aberration fluctuations during magnification. 4 <ft / fw<30 (12)

[0086] To obtain better characteristics, the lower limit of conditional expression (12) is more preferably 6, even more preferably 7, and even more preferably 8. To obtain better characteristics, the upper limit of conditional expression (12) is more preferably 20, even more preferably 13, and even more preferably 10.

[0087] When the focal length of the front intermediate lens group is fMf, it is preferable that the variable magnification optical system satisfies the following condition (13). By ensuring that the corresponding value in condition (13) does not fall below the lower limit, the refractive power of the second lens group G2 does not become too strong, which is advantageous in suppressing aberration fluctuations during magnification. By ensuring that the corresponding value in condition (13) does not exceed the upper limit, the refractive power of the second lens group G2 does not become too weak, which is advantageous in miniaturizing and widening the angle of the optical system. -3 <fMf / f2<-0.7 (13)

[0088] To obtain better characteristics, the lower limit of conditional equation (13) is more preferably -2.8, even more preferably -2.3, even more preferably -1.9, even more preferably -1.7, and even more preferably -1.5. To obtain better characteristics, the upper limit of conditional equation (13) is more preferably -0.8, even more preferably -0.9, even more preferably -1, even more preferably -1.05, and even more preferably -1.1.

[0089] The variable magnification optical system preferably satisfies the following condition (14). Here, βT2R is defined as the combined lateral magnification of all groups on the image side from the second lens group G2 when focused on an object at infinity at the telephoto end. βW2R is defined as the combined lateral magnification of all groups on the image side from the second lens group G2 when focused on an object at infinity at the wide-angle end. Ensuring that the corresponding value in condition (14) does not fall below the lower limit is advantageous for achieving a high magnification ratio. Ensuring that the corresponding value in condition (14) does not exceed the upper limit is advantageous for suppressing aberration fluctuations during magnification. 1.5 < βT2R / βW2R < 5 (14)

[0090] To obtain better characteristics, the lower limit of conditional equation (14) is more preferably 1.8, even more preferably 2, even more preferably 2.2, and even more preferably 2.4. To obtain better characteristics, the upper limit of conditional equation (14) is more preferably 4.3, even more preferably 4, even more preferably 3.8, and even more preferably 3.6.

[0091] The variable magnification optical system preferably satisfies the following condition (15). Here, βT2 is the lateral magnification of the second lens group G2 when focused on an object at infinity at the telephoto end. βW2 is the lateral magnification of the second lens group G2 when focused on an object at infinity at the wide-angle end. Ensuring that the corresponding value in condition (15) does not fall below the lower limit is advantageous for achieving a high magnification ratio. Ensuring that the corresponding value in condition (15) does not exceed the upper limit is advantageous for suppressing aberration fluctuations during magnification. 1.5 < βT2 / βW2 < 6 (15)

[0092] To obtain better characteristics, the lower limit of conditional expression (15) is more preferably 2, even more preferably 2.2, even more preferably 2.3, and even more preferably 2.4. To obtain better characteristics, the upper limit of conditional expression (15) is more preferably 5.5, even more preferably 5.1, even more preferably 5, and even more preferably 4.9.

[0093] When ωw is the maximum half-angle at the wide-angle end, it is preferable that the variable magnification optical system satisfies the following condition (16). Ensuring that the corresponding value in condition (16) does not fall below the lower limit is advantageous in suppressing aberration fluctuations during magnification. Ensuring that the corresponding value in condition (16) does not exceed the upper limit is advantageous in miniaturizing the optical system at the wide-angle end. 6 <TLw / (fw×tanωw)<10 (16)

[0094] To obtain better characteristics, the lower limit of conditional equation (16) is more preferably 6.5, and even more preferably 7. To obtain better characteristics, the upper limit of conditional equation (16) is more preferably 9.5, and even more preferably 8.8.

[0095] In a configuration where the first lens group G1 includes a positive lens and a negative lens, it is preferable that the variable magnification optical system satisfies the following condition (17). Here, νdn is the d-line reference Abbe number of the negative lens closest to the object among the negative lenses included in the variable magnification optical system. By ensuring that the corresponding value of condition (17) does not fall below the lower limit, it is possible to suppress insufficient refractive power of the negative lens closest to the object, which is caused by the difference between the Abbe numbers of the positive lens and the negative lens included in the first lens group G1 becoming too large, thus being advantageous for suppressing astigmatism at the wide-angle end. By ensuring that the corresponding value of condition (17) does not exceed the upper limit, it becomes easier to secure the difference between the Abbe numbers of the positive lens and the negative lens included in the first lens group G1, thus being advantageous for correcting chromatic aberration of the first lens group G1. 17<νdn<45 (17)

[0096] To obtain better characteristics, the lower limit of conditional expression (17) is more preferably 18, even more preferably 19, even more preferably 20, and even more preferably 20.5. To obtain better characteristics, the upper limit of conditional expression (17) is more preferably 40, even more preferably 36, even more preferably 30, and even more preferably 28.

[0097] When νdp is the Abbe number of the positive lens closest to the image line among the positive lenses included in the variable magnification optical system, it is preferable that the variable magnification optical system satisfies the following condition (18). By ensuring that the corresponding value of condition (18) does not fall below the lower limit, it is advantageous to suppress chromatic aberration occurring in the final lens group GE. By ensuring that the corresponding value of condition (18) does not exceed the upper limit, it becomes easier to select a material with a high refractive index for the final lens group GE, which is advantageous to suppress aberrations occurring in the final lens group GE. 48 < νdp < 78 (18)

[0098] To obtain better characteristics, the lower limit of conditional expression (18) is more preferably 58, even more preferably 60, even more preferably 62, and even more preferably 63.5. To obtain better characteristics, the upper limit of conditional expression (18) is more preferably 75, even more preferably 71.5, even more preferably 68.5, and even more preferably 67.5.

[0099] The preferred and possible configurations described above, including those relating to conditional expressions, can be combined in any way within the bounds of consistency, and are preferably selected selectively as appropriate according to the required specifications.

[0100] As an example, a preferred embodiment of the present disclosure is a variable magnification optical system comprising, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM consisting of multiple lens groups, and a final lens group GE having positive refractive power, wherein a front intermediate lens group having positive refractive power is positioned on the object side of the intermediate group GM, and a rear intermediate lens group having negative refractive power is positioned on the image side of the intermediate group GM, and when magnification is performed from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the spacing between all adjacent lens groups changes, satisfying the above condition (1).

[0101] Next, embodiments of the variable magnification optical system of this disclosure will be described with reference to the drawings. Note that the reference numerals assigned to each group in the cross-sectional view of each embodiment are used independently for each embodiment to avoid complexity in the explanation and drawings due to the increasing number of digits in the reference numerals. Therefore, even if common reference numerals are assigned in the drawings of different embodiments, they do not necessarily represent common configurations.

[0102] [Example 1] The configuration and movement trajectory of the variable magnification optical system of Example 1 are shown in Figure 1, and the method of illustration and configuration are as described above, so some redundant explanations will be omitted here. The variable magnification optical system of Example 1 consists of, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The intermediate group GM consists of the third lens group G3 and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5.

[0103] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fourth lens group G4. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0104] For the variable magnification optical system of Example 1, the basic lens data is shown in Table 1, the specifications and variable plane spacing are shown in Table 2, and the aspherical coefficients are shown in Tables 3A and 3B.

[0105] The basic lens data table is described as follows: The "Sn" column shows the surface number, with the surface closest to the object being designated as the 1st surface and the number increasing by one as you move toward the image side. The "R" column shows the radius of curvature of each surface. The "D" column shows the interplanar spacing on the optical axis between each surface and the surface adjacent to it on the image side. The "Nd" column shows the refractive index of each component with respect to the d line. The "νd" column shows the Abbe number of each component based on the d line. The "Material" column shows the material name of each component and the name of the manufacturer, separated by a period. The manufacturer names are generally shown as follows: "CDGM" refers to Chengdu Guangming Optoelectronics Co., Ltd. "NHG" refers to Hubei Xinhua Optoelectronics Materials Co., Ltd. "HOYA" refers to HOYA Corporation. "HIKARI" refers to Hikari Glass Co., Ltd. "SUMITA" refers to Sumita Optical Glass Co., Ltd. "OHARA" refers to Ohara Corporation. The "ED" column shows the effective diameter of each surface.

[0106] In the basic lens data table, the sign of the radius of curvature of a surface with a convex shape facing the object is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image is negative. The basic lens data table also shows the aperture diaphragm St and optical component PP. In the column for the surface number of the surface corresponding to the aperture diaphragm St, the surface number and the phrase (St) are entered. The value in the bottom column of column D in the table is the distance between the surface closest to the image in the table and the image plane Sim. For variable surface spacing, the symbol DD[ ] is used, and the surface number on the object side for this spacing is placed inside the [ ] and entered in the surface spacing column.

[0107] Table 2 shows the magnification ratio Zr, focal length f, back focus Bf in air equivalent distance, maximum aperture F-number FNo., maximum angle of view 2ω, and variable plane spacing relative to the d line. If the variable magnification optical system is a zoom lens, the magnification ratio is synonymous with the zoom magnification. The [°] in the 2ω column indicates that the unit is degrees. Table 2 shows the values ​​for the wide-angle end, intermediate focal length, and telephoto end for both the state when focused on an object at infinity and the state when focused on a nearby object. When focused on an object at infinity, "Infinity" is written in the object distance row, and when focused on a nearby object, the object distance to the nearest object is written in the object distance row. In Table 2, "0.2m" in the object distance column is a meter. Note that the object distance is the distance on the optical axis between the object that is the subject of the variable magnification optical system and the lens surface closest to the object in the variable magnification optical system. However, f and Bf are shown only for the state when focused on an object at infinity. In the rows for the magnification state, "Wide," "Middle," and "Tele" refer to the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

[0108] In the basic lens data table, the aspherical surface number is marked with an asterisk (*), and the column for the radius of curvature of the aspherical surface lists the value of the paraxial radius of curvature. In Table 3, the row labeled Sn shows the aspherical surface number, and the rows labeled KA and Am show the numerical value of the aspherical coefficient for each aspherical surface. Note that m in Am is an integer greater than or equal to 3 and varies depending on the surface. For example, in the 6th surface of Example 1, m = 3, 4, 5, ..., 16. The numerical value of the aspherical coefficient in Table 3, "E±n" (n: integer), is "×10 ±nThis means "[...]. KA and Am are the aspheric coefficients in the aspheric equation expressed by the following formula. Zd = C × h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2}+ΣAm×h m however, Zd: Aspherical depth (length of the perpendicular line drawn from a point on the aspherical surface at height h to a plane perpendicular to the optical axis Z to which the aspherical surface tangent is located). h: Height (distance from the optical axis Z to the lens surface) C: Reciprocal of the radius of paraxial curvature KA, Am: Aspherical coefficients Therefore, the Σ in aspherical formulas represents the summation with respect to m.

[0109] In the data in each table, degrees are used as the unit of angle, and millimeters are used as the unit of length, except for object distances in the specifications table. However, since optical systems can be used even with proportional enlargement or reduction, other appropriate units can also be used. In addition, the values ​​shown in the following tables are rounded to a predetermined number of decimal places.

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3A]

[0113] [Table 3B]

[0114] Figure 3 shows the aberration diagrams of the variable magnification optical system of Example 1 when focused on an object at infinity. In Figure 3, from left to right, the diagrams show spherical aberration, astigmatism, distortion, and chromatic aberration. In Figure 3, the upper section labeled "Wide" shows the aberrations at the wide-angle end, the middle section labeled "Middle" shows the aberrations at intermediate focal lengths, and the lower section labeled "Tele" shows the aberrations at the telephoto end. In the spherical aberration diagram, the aberrations along the d, C, F, and g lines are shown as solid lines, long dashed lines, short dashed lines, and dashed lines, respectively. In the astigmatism diagram, the aberration along the d line in the sagittal direction is shown as a solid line, and the aberration along the d line in the tangential direction is shown as a short dashed line. In the distortion diagram, the aberration along the d line is shown as a solid line. In the chromatic aberration diagram, the aberrations along the C and F lines are shown as long dashed lines and short dashed lines, respectively. In the spherical aberration diagram, the value of the wide-open aperture F-number is shown after FNo.=. In other aberration diagrams, the value of the maximum half-angle is shown after ω=.

[0115] The symbols, meanings, methods of description, and methods of illustration for each data point in Example 1 described above are basically the same in the following examples unless otherwise specified, so redundant explanations will be omitted below.

[0116] [Example 2] Figure 4 shows the configuration and movement trajectory of the variable magnification optical system of Example 2. The variable magnification optical system of Example 2 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0117] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0118] For the variable magnification optical system of Example 2, the basic lens data is shown in Table 4, the specifications and variable plane spacing in Table 5, the aspherical coefficients in Tables 6A and 6B, and the aberration diagrams are shown in Figure 5.

[0119] [Table 4]

[0120] [Table 5]

[0121] [Table 6A]

[0122] [Table 6B]

[0123] [Example 3] Figure 6 shows the configuration and movement trajectory of the variable magnification optical system of Example 3. The variable magnification optical system of Example 3 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0124] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0125] For the variable magnification optical system of Example 3, the basic lens data is shown in Table 7, the specifications and variable plane spacing in Table 8, the aspherical coefficients in Tables 9A and 9B, and the aberration diagrams are shown in Figure 7.

[0126] [Table 7]

[0127] [Table 8]

[0128] [Table 9A]

[0129] [Table 9B]

[0130] [Example 4] Figure 8 shows the configuration and movement trajectory of the variable magnification optical system of Example 4. The variable magnification optical system of Example 4 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0131] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0132] For the variable magnification optical system of Example 4, the basic lens data is shown in Table 10, the specifications and variable plane spacing are shown in Table 11, the aspherical coefficients are shown in Tables 12A and 12B, and the aberration diagrams are shown in Figure 9.

[0133] [Table 10]

[0134] [Table 11]

[0135] [Table 12A]

[0136] [Table 12B]

[0137] [Example 5] Figure 10 shows the configuration and movement trajectory of the variable magnification optical system of Example 5. The variable magnification optical system of Example 5 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0138] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0139] For the variable magnification optical system of Example 5, the basic lens data is shown in Table 13, the specifications and variable plane spacing in Table 14, the aspherical coefficient in Table 15, and the aberration diagrams in Figure 11.

[0140] [Table 13]

[0141] [Table 14]

[0142] [Table 15]

[0143] [Example 6] Figure 12 shows the configuration and movement trajectory of the variable magnification optical system of Example 6. The variable magnification optical system of Example 6 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0144] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0145] For the variable magnification optical system of Example 6, the basic lens data is shown in Table 16, the specifications and variable plane spacing are shown in Table 17, the aspherical coefficient is shown in Table 18, and the aberration diagrams are shown in Figure 13.

[0146] [Table 16]

[0147] [Table 17]

[0148] [Table 18]

[0149] [Example 7] Figure 14 shows the configuration and movement trajectory of the variable magnification optical system of Example 7. The variable magnification optical system of Example 7 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0150] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0151] For the variable magnification optical system of Example 7, the basic lens data is shown in Table 19, the specifications and variable plane spacing are shown in Table 20, the aspherical coefficient is shown in Table 21, and the aberration diagrams are shown in Figure 15.

[0152] [Table 19]

[0153] [Table 20]

[0154] [Table 21]

[0155] [Example 8] Figure 16 shows the configuration and movement trajectory of the variable magnification optical system of Example 8. The variable magnification optical system of Example 8 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0156] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0157] For the variable magnification optical system of Example 8, the basic lens data is shown in Table 22, the specifications and variable plane spacing in Table 23, the aspherical coefficient in Table 24, and the aberration diagrams in Figure 17.

[0158] [Table 22]

[0159] [Table 23]

[0160] [Table 24]

[0161] [Example 9] Figure 18 shows the configuration and movement trajectory of the variable magnification optical system of Example 9. The variable magnification optical system of Example 9 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0162] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0163] For the variable magnification optical system of Example 9, the basic lens data is shown in Table 25, the specifications and variable plane spacing in Table 26, the aspherical coefficient in Table 27, and the aberration diagrams in Figure 19.

[0164] [Table 25]

[0165] [Table 26]

[0166] [Table 27]

[0167] [Example 10] Figure 20 shows the configuration and movement trajectory of the variable magnification optical system of Example 10. The variable magnification optical system of Example 10 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0168] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image.

[0169] For the variable magnification optical system of Example 10, the basic lens data is shown in Table 28, the specifications and variable plane spacing in Table 29, the aspherical coefficient in Table 30, and the aberration diagrams in Figure 21.

[0170] [Table 28]

[0171] [Table 29]

[0172] [Table 30]

[0173] [Example 11] Figure 22 shows the configuration and movement trajectory of the variable magnification optical system of Example 11. The variable magnification optical system of Example 11 consists of, in order from the object side to the image side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. The intermediate group GM consists of the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE consists of the sixth lens group G6.

[0174] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z by changing the spacing between adjacent lens groups. The focusing group consists of the fifth lens group G5. When focusing from an object at infinity to a nearby object, the focusing group moves towards the image. For the variable magnification optical system of Example 11, the basic lens data is shown in Table 31, the specifications and variable plane spacing in Table 32, the aspherical coefficient in Table 33, and the aberration diagrams in Figure 23.

[0175] [Table 31]

[0176] [Table 32]

[0177] [Table 33]

[0178] Table 34 shows the corresponding values ​​for the conditional equations (1) to (18) of the variable magnification optical systems in Examples 1 to 11 described above. The corresponding values ​​shown in Table 34 may be used as the upper or lower limits of the conditional equations to set a preferred range for the conditional equations.

[0179] [Table 34]

[0180] The variable magnification optical systems of Examples 1 to 11 have a wide field of view, with a maximum total angle of view of 85 degrees or more at the wide-angle end. Furthermore, the variable magnification optical systems of Examples 1 to 11 have a magnification ratio of 6 times or more, achieving a high magnification ratio. Moreover, despite their compact configuration, the variable magnification optical systems of Examples 1 to 11 maintain high optical performance with aberrations well corrected throughout the entire magnification range.

[0181] Next, an imaging device according to an embodiment of the present disclosure will be described. Figures 24 and 25 show external views of a camera 30, which is an imaging device according to one embodiment of the present disclosure. Figure 24 shows a perspective view of the camera 30 from the front, and Figure 25 shows a perspective view of the camera 30 from the rear. The camera 30 is a so-called mirrorless type digital camera, and an interchangeable lens 20 can be detachably attached. The interchangeable lens 20 is configured to include a variable magnification optical system 1 according to one embodiment of the present disclosure, which is housed in the lens barrel.

[0182] The camera 30 comprises a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display captured images and images within the field of view before the image was captured.

[0183] A shooting aperture is provided in the center of the front of the camera body 31, through which light from the subject being photographed enters. A mount 37 is provided at a position corresponding to the shooting aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0184] An image sensor 38 is provided inside the camera body 31. The image sensor 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) can be used as the image sensor 38. The camera body 31 also contains a signal processing circuit (not shown) and a recording medium (not shown). The signal processing circuit processes the imaging signal output from the image sensor 38 to generate an image. The recording medium is for recording the generated image. With the camera 30, still images or videos can be taken by pressing the shutter button 32, and the image data obtained from this shooting is recorded on the recording medium.

[0185] Although the technology of this disclosure has been described above with reference to embodiments and examples, the technology of this disclosure is not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, interplanar spacing, refractive index, Abbe number, and aspheric coefficient of each lens are not limited to the values ​​shown in each of the above embodiments, but can take other values.

[0186] Furthermore, the imaging device according to the embodiments of this disclosure is not limited to the above examples, and can take various forms, such as cameras other than mirrorless types, cameras in which the imaging lens and camera body are integrally configured, film cameras, video cameras, surveillance cameras, broadcast cameras, movie cameras, FA (Factory Automation) cameras, and MV (Machine Vision) cameras.

[0187] The following additional information is disclosed regarding the above embodiments and examples. [Note 1] From the object side to the image side, it consists of a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group consisting of multiple lens groups, and a final lens group with positive refractive power. A front intermediate lens group having positive refractive power is positioned at the object-side end of the aforementioned intermediate group. A rear intermediate lens group with negative refractive power is positioned at the image-side end of the aforementioned intermediate group. When changing magnification from the wide-angle end to the telephoto end, the first lens group moves toward the object, and the spacing between all adjacent lens groups changes. The focal length of the first lens group is f1, When the focal length of the second lens group is set to f2, -0.25 <f2 / f1<-0.05 (1) A variable magnification optical system that satisfies the condition (1) expressed by . [Note 2] The first lens group is a variable magnification optical system as described in Appendix 1, comprising, in order from the object side to the image side, a negative meniscus lens with a convex surface on the object side, a positive lens, and another positive lens. [Note 3] The variable magnification optical system described in Appendix 1 or Appendix 2, wherein a positive lens with a convex image-side surface is positioned at the image-side end of the final lens group. [Note 4] The difference between the distance along the optical axis from the lens surface closest to the object of the first lens group to the image plane at the wide-angle end and the distance along the optical axis from the lens surface closest to the object of the first lens group to the image plane at the telephoto end is ZDD1. When the focal length of the variable magnification optical system at the wide-angle end is fw, 2 <ZDD1 / fw<15 (2) A variable magnification optical system described in any one of the appendices 1 to 3 that satisfies the conditional equation (2) represented by . [Note 5] A negative meniscus lens, whose object-facing surface is convex, is positioned at the object-facing end of the first lens group. If the refractive index of the negative meniscus lens closest to the object in the first lens group is Nd1 with respect to the d line, 1.7 <Nd1<2.4 (3) A variable magnification optical system described in any one of the appendices 1 to 4 that satisfies the conditional equation (3) represented by . [Note 6] If NdEr is the refractive index of the positive lens on the image side of the final lens group with respect to the d line, 1.43 <NdEr<1.85 (4) The zoom optical system according to Appendix 3 that satisfies the conditional expression (4) represented by [Appendix 7] At the wide-angle end, the sum of the distance on the optical axis from the most object-side lens surface of the first lens group to the most image-side lens surface of the final lens group and the back focus at the air-equivalent distance of the zoom optical system is defined as TLw. When the back focus at the air-equivalent distance of the zoom optical system at the wide-angle end is defined as Bfw, 4 < TLw / Bfw < 12 (5) The zoom optical system according to any one of Appendices 1 to 6 that satisfies the conditional expression (5) represented by [Appendix 8] At the telephoto end, the sum of the distance on the optical axis from the most object-side lens surface of the first lens group to the most image-side lens surface of the final lens group and the back focus at the air-equivalent distance of the zoom optical system is defined as TLt. When the focal length of the zoom optical system at the telephoto end is defined as ft, 0.85 < TLt / ft < 3 (6) The zoom optical system according to any one of Appendices 1 to 7 that satisfies the conditional expression (6) represented by [Appendix 9] When the focal length of the final lens group is defined as fE, 0.9 < f1 / fE < 3 (7) The zoom optical system according to any one of Appendices 1 to 8 that satisfies the conditional expression (7) represented by [Appendix 10] At the wide-angle end, the sum of the distance on the optical axis from the most object-side lens surface of the first lens group to the most image-side lens surface of the final lens group and the back focus at the air-equivalent distance of the zoom optical system is defined as TLw. When the focal length of the zoom optical system at the wide-angle end is defined as fw, 6 < TLw / fw < 10 (8) The zoom optical system according to any one of Appendices 1 to 9 that satisfies the conditional expression (8) represented by [Appendix 11] When the refractive index with respect to the d line of the most object-side positive lens among the positive lenses included in the first lens group is defined as Nd1p, 1.43 < Nd1p < 1.72 (9) The zoom optical system according to any one of Appendices 1 to 10 that satisfies the conditional expression (9) represented by [Appendix 12] The zoom optical system according to Appendix 3, wherein the positive lens on the most image side of the final lens group is a meniscus lens. [Appendix 13] The zoom optical system according to any one of Appendices 1 to 12, wherein the final lens group is fixed with respect to the image plane during zooming. [Appendix 14] When the focal length of the rear intermediate lens group is fMr, and the focal length of the final lens group is fE, -1.5 < fMr / fE < -0.1 (10) The zoom optical system according to any one of Appendices 1 to 13 that satisfies the conditional expression (10) represented by [Appendix 15] When the back focus at the air equivalent distance of the zoom optical system at the wide-angle end is Bfw, and the focal length of the zoom optical system at the wide-angle end is fw, 0.8 < Bfw / fw < 2 (11) The zoom optical system according to any one of Appendices 1 to 14 that satisfies the conditional expression (11) represented by [Appendix 16] When the focal length of the zoom optical system at the telephoto end is ft, and the focal length of the zoom optical system at the wide-angle end is fw, 4 < ft / fw < 30 (12) The zoom optical system according to any one of Appendices 1 to 15 that satisfies the conditional expression (12) represented by [Appendix 17] When the focal length of the front intermediate lens group is fMf, -3 < fMf / f2 < -0.7 (13) The zoom optical system according to any one of Appendices 1 to 16 that satisfies the conditional expression (13) represented by [Appendix 18] When focused on an object at infinity at the telephoto end, the combined lateral magnification of all groups on the image side from the second lens group is βT2R. When the combined lateral magnification of all groups on the image side from the second lens group is βW2R in a state where the object at infinity is in focus at the wide-angle end, 1.5 < βT2R / βW2R < 5 (14) A variable magnification optical system described in any one of the appendices 1 to 17 that satisfies the conditional equation (14) represented by . [Note 19] The lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is βT2, When the lateral magnification of the second lens group is βW2 when focused on an object at infinity at the wide-angle end, 1.5 < βT2 / βW2 < 6 (15) A variable magnification optical system described in any one of the appendices 1 to 18 that satisfies the conditional equation (15) represented by . [Note 20] An imaging device equipped with a variable magnification optical system as described in any one of the appendices 1 to 19. [Explanation of Symbols]

[0188] 1. Variable magnification optical system 20 interchangeable lenses 30 Cameras 31 Camera Body 32 Shutter button 33 Power button 34 Control section 35 Control section 36 Display section 37 Mount 38 Image sensor G1 First Lens Group G2 Second Lens Group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group GE Final Lens Series GM intermediate group L11~L51 Lenses PP optical components Sim image plane St aperture stop Z optical axis ZDD1 difference ωt maximum half angle of view ωw maximum half angle of view

Claims

1. Starting from the object side and moving towards the image side, the lens consists of a first lens group with positive refractive power, a second lens group with negative refractive power, an intermediate group consisting of multiple lens groups, and a final lens group with positive refractive power. A front intermediate lens group having positive refractive power is positioned at the object-side end of the aforementioned intermediate group. A rear intermediate lens group with negative refractive power is positioned at the image-side end of the aforementioned intermediate group. When changing magnification from the wide-angle end to the telephoto end, the first lens group moves toward the object, and the spacing between all adjacent lens groups changes. The focal length of the first lens group is f1, When the focal length of the second lens group is set to f2, -0.25<f2 / f1<-0.05 (1) A variable magnification optical system that satisfies the condition (1) represented by .

2. The variable magnification optical system according to claim 1, wherein the first lens group comprises, in order from the object side to the image side, a negative meniscus lens having a convex surface on the object side, a positive lens, and a positive lens.

3. The variable magnification optical system according to claim 1, wherein a positive lens having a convex surface on the image side is arranged at the image side of the final lens group.

4. The difference between the distance along the optical axis from the lens surface closest to the object of the first lens group to the image plane at the wide-angle end and the distance along the optical axis from the lens surface closest to the object of the first lens group to the image plane at the telephoto end is ZDD1. When the focal length of the variable magnification optical system at the wide-angle end is fw, 2<ZDD1 / fw<15 (2) A variable magnification optical system according to claim 1 that satisfies the conditional expression (2) represented by .

5. A negative meniscus lens, whose object-facing surface is convex, is positioned at the object-facing end of the first lens group. When the refractive index of the negative meniscus lens closest to the object in the first lens group is Nd1 with respect to the d line, 1.7<Nd1<2.4 (3) A variable magnification optical system according to claim 1 that satisfies the conditional expression (3) represented by .

6. When NdEr is the refractive index of the positive lens on the image side of the final lens group with respect to the d line, 1.43<NdEr<1.85 (4) A variable magnification optical system according to claim 3 that satisfies the conditional expression (4) represented by .

7. At the wide-angle end, the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the final lens group, and the back focus of the variable magnification optical system in air equivalent distance is TLw. When the back focus of the variable magnification optical system at the wide-angle end is Bfw in terms of the air-equivalent distance, 4<TLw / Bfw<12 (5) A variable magnification optical system according to claim 1 that satisfies the conditional expression (5) represented by .

8. At the telephoto end, TLt is the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the final lens group, and the back focus of the variable magnification optical system in air equivalent distance. When the focal length of the variable magnification optical system at the telephoto end is denoted as ft, 0.85<TLt / ft<3 (6) A variable magnification optical system according to claim 1 that satisfies the conditional expression (6) represented by .

9. When the focal length of the final lens group is denoted as fE, 0.9<f1 / fE<3 (7) A variable magnification optical system according to claim 1 that satisfies the conditional expression (7) represented by .

10. At the wide-angle end, the sum of the distance along the optical axis from the lens surface closest to the object in the first lens group to the lens surface closest to the image in the final lens group, and the back focus of the variable magnification optical system in air equivalent distance is TLw. When the focal length of the variable magnification optical system at the wide-angle end is fw, 6<TLw / fw<10 (8) A variable magnification optical system according to claim 1 that satisfies the conditional expression (8) represented by .

11. If the refractive index of the positive lens closest to the object among the positive lenses included in the first lens group is Nd1p with respect to the d line, 1.43<Nd1p<1.72 (9) A variable magnification optical system according to claim 1 that satisfies the conditional expression (9) represented by .

12. The variable magnification optical system according to claim 3, wherein the positive lens on the image side of the final lens group is a meniscus lens.

13. The variable magnification optical system according to claim 1, wherein the final lens group is fixed with respect to the image plane during magnification.

14. The focal length of the aforementioned rear intermediate lens group is fMr, When the focal length of the final lens group is denoted as fE, -1.5<fMr / fE<-0.1 (10) A variable magnification optical system according to claim 1 that satisfies the conditional expression (10) represented by .

15. At the wide-angle end, the back focus of the variable magnification optical system in terms of air equivalent distance is Bfw. When the focal length of the variable magnification optical system at the wide-angle end is fw, 0.8<Bfw / fw<2 (11) A variable magnification optical system according to claim 1 that satisfies the conditional expression (11) represented by .

16. The focal length of the variable magnification optical system at the telephoto end is ft, When the focal length of the variable magnification optical system at the wide-angle end is fw, 4<ft / fw<30 (12) A variable magnification optical system according to claim 1 that satisfies the conditional expression (12) represented by .

17. When the focal length of the front intermediate lens group is denoted as fMf, -3<fMf / f2<-0.7 (13) A variable magnification optical system according to claim 1 that satisfies the conditional expression (13) represented by .

18. When the lens is in focus on an object at infinity at the telephoto end, the combined lateral magnification of all lens groups on the image side from the second lens group is βT2R. When the combined lateral magnification of all groups on the image side from the second lens group is βW2R in a state where the object at infinity is in focus at the wide-angle end, 1.5<βT2R / βW2R<5 (14) A variable magnification optical system according to claim 1 that satisfies the conditional expression (14) represented by .

19. The lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is βT2, When the lateral magnification of the second lens group is βW2 in a state where it is in focus on an object at infinity at the wide-angle end, 1.5<βT2 / βW2<6 (15) A variable magnification optical system according to claim 1 that satisfies the conditional expression (15) represented by .

20. An imaging apparatus comprising a variable magnification optical system according to any one of claims 1 to 19.

Images