Optical Department

Abstract

By appropriately using the glass materials of the lenses that make up each lens group, we provide an optical system that achieves weight reduction while correcting various aberrations such as chromatic aberration. [Solution] An optical system is provided, characterized by having a lens LA that satisfies a predetermined condition, configured by arranging an object-side lens group GF and an image-plane-side lens group GR in order from the object side.

Description

Technical Field

[0001] The present invention relates to an optical system suitable for a lens used in an imaging device such as a still camera or a video camera, or a projection device, and relates to an optical system capable of effectively correcting chromatic aberration.

Background Art

[0002] In recent years, with the increase in pixel count of digital cameras and the like, there has been a growing demand for strict correction of various aberrations in optical systems used in imaging devices, projection devices, and the like.

[0003] Therefore, in conventionally proposed optical systems, those using special low-dispersion glass and correcting chromatic aberration from the C line to the g line in the wavelength range have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the above-described conventional technologies had the following problems.

[0006] Patent Document 1 proposes a variable magnification optical system that uses special low-dispersion glass equivalent to HOYA's FCD1 to achieve a wide field of view at the wide-angle end and suppress axial chromatic aberration. However, the optical system described in Patent Document 1 has the problem that the correction of magnification chromatic aberration is not sufficient, especially at the wide-angle end.

[0007] Furthermore, Patent Document 2 proposes an optical system that suppresses axial chromatic aberration while maintaining a wide field of view. However, the optical system described in Patent Document 2 has a problem in that color flare tends to remain from the intermediate field of view to the edges of the screen due to the shift in the image point in the optical axis direction from the C line to the F line.

[0008] Furthermore, Patent Document 3 proposes an optical system that suppresses axial chromatic aberration by using special low-dispersion glass equivalent to calcium fluoride. However, the optical system described in Patent Document 3 has the problem that it does not adequately correct magnification chromatic aberration from the g-line to the h-line.

[0009] Furthermore, Patent Document 4 proposes a variable magnification optical system that suppresses axial chromatic aberration at the telephoto end by using special low-dispersion glass equivalent to HOYA's FCD1. However, the variable magnification optical system described in Patent Document 4 has the problem that the correction of axial chromatic aberration is insufficient at the wide-angle end, and the correction of magnification chromatic aberration is insufficient at the telephoto end.

[0010] This invention has been made in view of at least one of these problems, and aims to provide an optical system that corrects various aberrations such as chromatic aberration by appropriately using lens materials. [Means for solving the problem]

[0011] To achieve the above objective, the optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF and an image-plane side lens group GR, wherein the object-side lens group GF has a negative refractive power as a whole, and the image-plane side lens group GR has a positive refractive power as a whole. At least one of the object-side lens group GF or the image plane-side lens group GR has a lens LA that satisfies the following condition (1). (1) VD_A > 96.00 however, VD_A: Abbe number with reference to the d line of the lens LA.

[0012] Furthermore, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following condition (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: The mean value of the deviation ΔθgF of the partial dispersion ratio of the lens LA with respect to the g line. Here, the deviation ΔθgF of the partial variance ratio relative to the g line is given by, where θgF is the partial variance ratio relative to the g line and VD is the Abbe number on the d line. ΔθgF=θgF-(0.648285-0.00180123×VD) This is calculated for each lens.

[0013] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during magnification. The lens LA is arranged in the object-side lens group GF and is characterized by having a negative refractive power.

[0014] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during magnification. The lens LA is arranged in the image-plane side lens group GR and is characterized by having a positive refractive power.

[0015] Further, in the optical system according to the present invention, preferably, when the optical system is zoomed, in the state of being focused at infinity in the most wide-angle state, or when the optical system is not zoomed, in the state of being focused at infinity, among the air gaps between adjacent lenses of the optical system, the lens group interval between the object-side lens group GF and the image-side lens group GR is the largest. The lens LA is arranged in the object-side lens group GF and has a negative refractive power.

[0016] Further, in the optical system according to the present invention, preferably, when the optical system is zoomed, in the state of being focused at infinity in the most wide-angle state, or when the optical system is not zoomed, in the state of being focused at infinity, among the air gaps between adjacent lenses of the optical system, the lens group interval between the object-side lens group GF and the image-side lens group GR is the largest. The lens LA is arranged in the image-side lens group GR and has a positive refractive power.

[0017] Further, the optical system according to the present invention preferably has a lens group GFA that includes the lens LA and has a negative refractive power. When the optical system is zoomed, when dividing the object-side lens group GF into lens groups with all the air gaps that change during zooming as boundaries, the lens group GFA is arranged on the most image-side of the object-side lens group GF, or the lens group GFA is the same as the object-side lens group GF. When the optical system is not zoomed, the lens group GFA is the same as the object-side lens group GF. The lens group GFA is characterized by being composed of four or more lenses.

[0018] Further, the optical system according to the present invention preferably has an aspherical surface in which the positive refractive power becomes stronger or the negative refractive power becomes weaker at the periphery of the effective light diameter with respect to the optical axis center in the object-side lens group GF.

[0019] Further, the optical system according to the present invention preferably has an aspherical surface in which the image plane side lens group GR has a weakened positive refractive power or an enhanced negative refractive power at the periphery of the effective light diameter with respect to the optical axis center.

[0020] In order to achieve the above object, the optical system according to the present invention is configured by arranging an object side lens group GF and an image plane side lens group GR in order from the object side. An aperture stop is arranged between the object side lens group GF and the image plane side lens group GR. The object side lens group GF has a positive or negative refractive power as a whole, and the image plane side lens group GR has a positive refractive power as a whole. At least one of the object side lens group GF or the image plane side lens group GR has a lens LA that satisfies the following conditional expression (1). (1) VD_A > 96.00 However, VD_A: Abbe number of the lens LA based on the d-line

[0021] Further, the optical system according to the present invention preferably has the lens LA that satisfies the following conditional expression (2). (2) ΔθgF_A > 0.057 However, ΔθgF_A: Average value of the deviation ΔθgF of the partial dispersion ratio with respect to the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio with respect to the g-line is calculated for each lens as follows: when the partial dispersion ratio with respect to the g-line is θgF and the Abbe number at the d-line is VD, ΔθgF = θgF - (0.648285 - 0.00180123 × VD) is calculated for each lens.

[0022] Further, when the optical system according to the present invention is zoomed, the interval between at least the object side lens group GF and the image plane side lens group GR changes during zooming. The lens LA is arranged in the object side lens group GF and has a negative refractive power.

[0023] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during magnification. The lens LA is arranged in the image-plane side lens group GR and is characterized by having a positive refractive power.

[0024] Furthermore, the optical system according to the present invention is preferably characterized in that, when the optical system is magnified, in the widest angle state and in focus at infinity, or when the optical system is not magnified, in the state in focus at infinity, the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis is higher than the height of the on-axial marginal rays passing through the optical surface closest to the object of the optical system from the optical axis.

[0025] Furthermore, the optical system according to the present invention preferably includes the lens LA and a lens group GFA having negative refractive power, When the optical system is magnified, the object-side lens group GF is divided into lens groups with all of the air gaps that change during magnification as boundaries, and the lens group GFA is positioned closest to the object among the negative refractive power lens groups included in the object-side lens group GF. If the optical system does not change magnification, when the object-side lens group GF is divided into lens groups with all the air gaps that change during focusing as boundaries, the lens group GFA is positioned closest to the object among the negative refractive power lens groups included in the object-side lens group GF. The aforementioned lens group GFA is characterized by being composed of four or more lenses.

[0026] Furthermore, the optical system according to the present invention is preferably characterized in that the object-side lens group GF has an aspherical surface in which the positive refractive power is stronger or the negative refractive power is weaker in the vicinity of the effective ray diameter with respect to the optical axis center.

[0027] Furthermore, the optical system according to the present invention is preferably characterized in that the image-plane side lens group GR has an aspherical surface in which the positive refractive power weakens or the negative refractive power strengthens in the vicinity of the effective ray diameter with respect to the optical axis center.

[0028] Furthermore, in order to achieve the above objective, the optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF having a positive refractive power and an image-plane-side lens group GR, and has an aperture diaphragm and a lens LA that satisfies the following condition (1). (1) VD_A > 96.00 however, VD_A: Abbe number with reference to the d line of the lens LA.

[0029] Furthermore, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following condition (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: The mean value of the deviation ΔθgF of the partial dispersion ratio of the lens LA with respect to the g line. Here, the deviation ΔθgF of the partial variance ratio relative to the g line is given by, where θgF is the partial variance ratio relative to the g line and VD is the Abbe number on the d line. ΔθgF=θgF-(0.648285-0.00180123×VD) This is calculated for each lens.

[0030] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during magnification. The lens LA is positioned in the object-side lens group GF and has a positive refractive power. It is characterized by satisfying the following condition (3). (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0031] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during magnification. The aforementioned lens LA is arranged in the image plane side lens group GR and has a negative refractive power. It is characterized by satisfying the following condition (4). (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance on the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR, when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0032] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, in the state where it is focused at infinity in the most telephoto state, or when the optical system is not magnified, in the state where it is focused at infinity, the distance between the lens groups of the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses of the optical system. The lens LA is positioned in the object-side lens group GF and has a positive refractive power. It is characterized by satisfying the following condition (3). (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0033] Furthermore, in the optical system according to the present invention, preferably, when the optical system is magnified, in the state where it is focused at infinity in the most telephoto state, or when the optical system is not magnified, in the state where it is focused at infinity, the distance between the lens groups of the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses of the optical system. The aforementioned lens LA is arranged in the image plane side lens group GR and has a negative refractive power. It is characterized by satisfying the following condition (4). (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance on the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR, when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0034] Furthermore, the optical system according to the present invention is preferably characterized by satisfying the following condition (5). (5) 0.40 > DFR / LT > 0.10 however, If the optical system does not change magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image plane-side lens group GR when the lens is focused at infinity. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the system is focused at infinity. When the optical system changes magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image-plane lens group GR when the object is in focus at infinity at its longest telephoto setting. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the optical system is in focus at infinity at its most telephoto setting.

[0035] Furthermore, in order to achieve the above objective, the optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF having a positive refractive power and an image-plane side lens group GR, with an aperture diaphragm placed between the object-side lens group GF and the image-plane side lens group GR, and having a lens LA that satisfies the following condition (1). (1) VD_A > 96.00 however, VD_A: Abbe number with reference to the d line of the lens LA.

[0036] Furthermore, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following condition (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: The mean value of the deviation ΔθgF of the partial dispersion ratio of the lens LA with respect to the g line. Here, the deviation ΔθgF of the partial variance ratio relative to the g line is given by, where θgF is the partial variance ratio relative to the g line and VD is the Abbe number on the d line. ΔθgF=θgF-(0.648285-0.00180123×VD) This is calculated for each lens.

[0037] Furthermore, in the optical system according to the present invention, preferably, the lens LA is arranged in the object-side lens group GF and has a positive refractive power. It is characterized by satisfying the following condition (3). (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0038] Furthermore, in the optical system according to the present invention, preferably, the lens LA is arranged in the image plane side lens group GR and has a negative refractive power. It is characterized by satisfying the following condition (4). (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance on the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR, when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0039] Furthermore, the optical system according to the present invention is preferably characterized in that, when the optical system is magnified, in the state where it is focused on infinity in the most telephoto state, or when the optical system is not magnified, in the state where it is focused on infinity, the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis is lower than the height of the on-axial marginal rays passing through the optical surface closest to the object of the optical system from the optical axis.

[0040] Furthermore, the optical system according to the present invention is preferably characterized by satisfying the following condition (6). (6) 0.70 > HS / HR1 > 0.20 however, If the optical system does not change magnification, HS: The height from the optical axis of the on-axial marginal rays passing through the aperture diaphragm when the focus is set to infinity. HR1: The height from the optical axis of the on-axial marginal ray passing through the optical surface closest to the object in the optical system when in focus at infinity. When the optical system changes magnification, HS: The height from the optical axis of the on-axial marginal rays passing through the aperture diaphragm when the focus is on infinity at the most telephoto setting. HR1: The height from the optical axis of the on-axial marginal ray passing through the optical surface closest to the object in the optical system when it is focused at infinity at its most telephoto setting. [Effects of the Invention]

[0041] According to the optical system of the present invention, by appropriately using the glass material of the lenses constituting each lens group, it is possible to provide an optical system that achieves weight reduction while correcting various aberrations such as chromatic aberration. [Brief explanation of the drawing]

[0042] [Figure 1] This is a diagram of the lens configuration of the variable magnification optical system of Example 1 when it is focused at infinity at the wide-angle end. [Figure 2] This is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at the wide-angle end. [Figure 3]This is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at the intermediate focal length. [Figure 4] This is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at its telephoto end. [Figure 5] This is a lateral aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at the wide-angle end. [Figure 6] This is a lateral aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at the intermediate focal length. [Figure 7] This is a lateral aberration diagram of the variable magnification optical system of Example 1 when it is focused at infinity at its telephoto end. [Figure 8] This is a lens configuration diagram of the variable magnification optical system of Example 2 when it is focused at infinity at the wide-angle end. [Figure 9] This is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when it is focused at infinity at the wide-angle end. [Figure 10] This is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when the intermediate focal length is focused at infinity. [Figure 11] This is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when it is focused at infinity at its telephoto end. [Figure 12] This is a lateral aberration diagram of the variable magnification optical system of Example 2 when it is focused at infinity at the wide-angle end. [Figure 13] This is a lateral aberration diagram of the variable magnification optical system of Example 2 when the intermediate focal length is focused at infinity. [Figure 14] This is a lateral aberration diagram of the variable magnification optical system of Example 2 when it is focused at infinity at its telephoto end. [Figure 15] This is a diagram of the lens configuration of the optical system in Example 3 when it is focused at infinity. [Figure 16] This is a longitudinal aberration diagram of the optical system of Example 3 when it is focused at infinity. [Figure 17] This is a longitudinal aberration diagram of the optical system of Example 3 at a shooting distance of 245 mm. [Figure 18] This is a diagram of the lateral aberration of the optical system of Example 3 when it is focused at infinity. [Figure 19]This is a lateral aberration diagram of the optical system of Example 3 at a shooting distance of 245 mm. [Figure 20] This is a lens configuration diagram of the optical system of Example 4 when it is focused at infinity. [Figure 21] This is a longitudinal aberration diagram of the optical system of Example 4 when it is focused at infinity. [Figure 22] This is a longitudinal aberration diagram of the optical system of Example 4 at a shooting distance of 230 mm. [Figure 23] This is a diagram of the lateral aberration of the optical system of Example 4 when it is focused at infinity. [Figure 24] This is a lateral aberration diagram of the optical system of Example 4 at a shooting distance of 230 mm. [Figure 25] This is a lens configuration diagram of the variable magnification optical system of Example 5 when it is focused at infinity at the wide-angle end. [Figure 26] This is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when it is focused at infinity at the wide-angle end. [Figure 27] This is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when the intermediate focal length is focused at infinity. [Figure 28] This is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when it is focused at infinity at its telephoto end. [Figure 29] This is a diagram of the lateral aberration of the variable magnification optical system of Example 5 when it is focused at infinity at the wide-angle end. [Figure 30] This is a lateral aberration diagram of the variable magnification optical system of Example 5 when the intermediate focal length is focused at infinity. [Figure 31] This is a lateral aberration diagram of the variable magnification optical system of Example 5 when it is focused at infinity at its telephoto end. [Figure 32] This is a lens configuration diagram of the optical system of Example 6 when it is focused at infinity. [Figure 33] This is a longitudinal aberration diagram of the optical system of Example 6 when it is focused at infinity. [Figure 34] This is a longitudinal aberration diagram of the optical system of Example 6 at a shooting distance of 2675 mm. [Figure 35] This is a diagram of the lateral aberration of the optical system of Example 6 when it is focused at infinity. [Figure 36] This is a lateral aberration diagram of the optical system of Example 6 at a shooting distance of 2675 mm. [Figure 37] This is a diagram of the lens configuration of the optical system in Example 7 when it is focused at infinity. [Figure 38] This is a longitudinal aberration diagram of the optical system of Example 7 when it is focused at infinity. [Figure 39] This is a longitudinal aberration diagram of the optical system of Example 7 at a shooting distance of 800 mm. [Figure 40] This is a diagram of the lateral aberration of the optical system of Example 7 when it is focused at infinity. [Figure 41] This is a lateral aberration diagram of the optical system of Example 7 at a shooting distance of 800 mm. [Modes for carrying out the invention]

[0043] The following describes in detail an embodiment of the optical system according to the present invention. Note that this description illustrates an example of the optical system according to the present invention, and the present invention is not limited to this embodiment without departing from its spirit.

[0044] The present invention aims to provide an optical system that effectively corrects various aberrations, such as chromatic aberration, and it is important to use appropriate glass materials for each lens that constitutes the optical system.

[0045] Conventionally, a known method for simultaneously correcting axial chromatic aberration and lateral chromatic aberration is to use a glass material with low wavelength dispersion of refractive index and high anomalous dispersion on the short-wavelength side near the g-line. However, since many such glass materials have low refractive indices, this is detrimental to controlling short-wavelength aberrations.

[0046] Furthermore, when using glass materials with low wavelength dispersion of the refractive index and high anomalous dispersion on the short wavelength side near the g-line, it was difficult to simultaneously correct axial chromatic aberration and lateral chromatic aberration, or, in the case of a variable magnification optical system, to correct chromatic aberration across the entire magnification range.

[0047] For example, calcium fluoride single crystals and low-dispersion / anomalous-dispersion glasses equivalent to HOYA's FCD100 have high Abbe numbers and g-line anomalous dispersion, making them effective in correcting chromatic aberration in primary and secondary spectra. However, it was difficult to correct chromatic aberration from the C-line to the g-line by using these materials alone.

[0048] Therefore, the optical system according to the present invention uses glass equivalent to the low-dispersion oxyfluoride glass described in International Publication No. 2017-124612 or SUMITA's ultra-low-dispersion fluoride glass K-FIR100UV, thereby correcting axial chromatic aberration and chromatic aberration from the C line to the g line, while also suppressing various aberrations such as astigmatism by reducing the number of special low-dispersion glass elements used and making it easier to use high-refractive-index glass in other areas.

[0049] The optical system according to the present invention has a lens LA that satisfies the following condition (1). (1) VD_A > 96.00 however, VD_A: Abbe number with reference to the d line of the lens LA.

[0050] Conditional equation (1) defines a preferred range for the Abbe number in the d-line of the lens LA of the optical system according to the present invention.

[0051] When the lower limit of condition (1) is exceeded and the Abbe number of lens LA on the d line becomes small, the ability of lens LA to correct chromatic aberration is insufficient, making it difficult to correct chromatic aberration while simultaneously distributing the effect of correcting single-wavelength aberrations to other lenses.

[0052] Furthermore, by setting the lower limit of condition (1) to 97.00, the effects of the present invention can be achieved more reliably.

[0053] Furthermore, it is desirable that the optical system according to the present invention satisfies the following condition (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: The mean value of the deviation ΔθgF of the partial dispersion ratio of the lens LA with respect to the g line. Here, the deviation ΔθgF of the partial variance ratio relative to the g line is given by, where θgF is the partial variance ratio relative to the g line and VD is the Abbe number on the d line. ΔθgF=θgF-(0.648285-0.00180123×VD) This is calculated for each lens.

[0054] Conditional equation (2) defines a preferred range for the partial dispersion ratio of lens LA with respect to the g-line in the optical system according to the present invention.

[0055] When the lower limit of condition (2) is exceeded and the average value of the deviation ΔθgF of the partial dispersion ratio of lens LA with respect to the g-line becomes small, it becomes difficult to correct the chromatic aberration of the second spectrum.

[0056] Furthermore, by setting the lower limit of condition (2) to 0.061, the effects of the present invention can be achieved more reliably.

[0057] The following describes examples of wide-angle to standard type and telephoto type optical systems having a lens LA that satisfies the predetermined condition formula described above. In these examples, Examples 1 to 4 are examples of wide-angle to standard type optical systems having a lens LA, and Examples 5 to 6 are examples of telephoto type optical systems having a lens LA.

[0058] [First Embodiment (Wide-angle to Standard Type Optical System)] Examples 1 to 4 of wide-angle to standard type optical systems having lens LA will be described.

[0059] The wide-angle to standard type optical system according to the present invention is configured by arranging an object-side lens group GF and an image-plane-side lens group GR in order from the object side, wherein the object-side lens group GF has a negative refractive power as a whole, and the image-plane-side lens group GR has a positive refractive power as a whole, and at least one of the object-side lens group GF or the image-plane-side lens group GR has a lens LA that satisfies the above-described condition.

[0060] This lens configuration makes it easier to secure back focus, especially in optical systems with a wide angle of view, and helps to suppress vignetting.

[0061] Alternatively, the wide-angle to standard type optical system according to the present invention is configured by arranging an object-side lens group GF and an image-plane-side lens group GR in order from the object side, with an aperture diaphragm positioned between the object-side lens group GF and the image-plane-side lens group GR, the object-side lens group GF having a positive or negative refractive power as a whole, the image-plane-side lens group GR having a positive refractive power as a whole, and at least one of the object-side lens group GF or the image-plane-side lens group GR having a lens LA that satisfies the above-described condition.

[0062] By using this lens configuration, it becomes easier to suppress aberrations of light rays incident on the edges of the image, especially in optical systems with wide-angle to standard angle of view, while ensuring sufficient back focus.

[0063] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the optical system is magnified, it is desirable that at least the distance between the object-side lens group GF and the image-plane-side lens group GR changes during magnification, and that lens LA is positioned in the object-side lens group GF and has negative refractive power.

[0064] By using this lens configuration, chromatic aberration can be effectively corrected both in optical systems that do not vary magnification and in each magnification state of optical systems that do vary magnification.

[0065] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the optical system is magnified, it is desirable that at least the distance between the object-side lens group GF and the image-plane-side lens group GR changes during magnification, and that lens LA is positioned in the image-plane-side lens group GR and has positive refractive power.

[0066] This lens configuration allows for effective correction of axial chromatic aberration and lateral chromatic aberration, both in optical systems that do not vary magnification and in each magnification state of optical systems that do vary magnification.

[0067] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the optical system is magnified, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum air distance between adjacent lenses of the optical system when it is focused at infinity in the widest angle state, or when the optical system is not magnified, when it is focused at infinity, and it is desirable that lens LA is positioned in the object-side lens group GF and has negative refractive power.

[0068] This lens configuration allows for effective correction of chromatic aberration in both non-magnifying optical systems and at the wide-angle end of variable-magnification optical systems.

[0069] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the optical system is magnified, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum air distance between adjacent lenses of the optical system when it is focused at infinity in the widest angle state, or when the optical system is not magnified, when it is focused at infinity, and it is desirable that lens LA is arranged in the image-plane-side lens group GR and has a positive refractive power.

[0070] This lens configuration allows for effective correction of axial chromatic aberration and lateral chromatic aberration, both in optical systems that do not vary magnification and at the wide-angle end of optical systems that do vary magnification.

[0071] Furthermore, in the wide-angle to standard type optical system according to the present invention, if the optical system is magnified, it is desirable that the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis is higher than the height of the on-axial marginal rays passing through the optical surface closest to the object of the optical system, when the optical system is magnified and in focus at infinity in the widest angle state, or when the optical system is not magnified and in focus at infinity.

[0072] By using this lens configuration, it becomes easier to secure back focus, both in optical systems that do not vary magnification and at the wide-angle end of optical systems that do vary magnification, and it also becomes easier to suppress vignetting.

[0073] Furthermore, the wide-angle to standard type optical system according to the present invention has a lens group GFA that includes lens LA and has negative refractive power, and when the optical system is magnified, when the object-side lens group GF is divided into lens groups with all of the air gaps that change during magnification as boundaries, the lens group GFA is positioned on the image plane side of the object-side lens group GF, or the lens group GFA is the same as the object-side lens group GF, and when the optical system is not magnified, the lens group GFA is the same as the object-side lens group GF, and it is desirable that the lens group GFA is composed of four or more lenses.

[0074] Alternatively, the wide-angle to standard type optical system according to the present invention has a lens group GFA that includes lens LA and has negative refractive power, and when the optical system is magnified, when the object-side lens group GF is divided into lens groups with all of the air gaps that change during magnification as boundaries, lens group GFA is positioned furthest towards the object among the negative refractive power lens groups included in the object-side lens group GF, and when the optical system is not magnified, when the object-side lens group GF is divided into lens groups with all of the air gaps that change during focusing as boundaries, lens group GFA is positioned furthest towards the object among the negative refractive power lens groups included in the object-side lens group GF, and it is desirable that lens group GFA is composed of four or more lenses.

[0075] By using this lens configuration, various aberrations such as astigmatism can be effectively corrected simultaneously with chromatic aberration in both non-magnifying optical systems and in each magnification state of a magnifying optical system.

[0076] Furthermore, in the wide-angle to standard type optical system according to the present invention, it is desirable that the object-side lens group GF has an aspherical surface in which the positive refractive power is stronger or the negative refractive power is weaker at the periphery of the effective ray diameter with respect to the optical axis center.

[0077] This lens configuration allows for effective correction of distortion.

[0078] Furthermore, in the wide-angle to standard type optical system according to the present invention, it is desirable that the image-plane lens group GR has an aspherical surface in which the positive refractive power weakens or the negative refractive power strengthens at the periphery of the effective ray diameter with respect to the optical axis center.

[0079] This lens configuration allows for effective correction of various aberrations such as distortion and field curvature.

[0080] [Second Embodiment (Telephoto Type Optical System)] Examples 5 to 7 of telephoto-type optical systems having lens LA will be described.

[0081] The telephoto optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF having a positive refractive power and an image-plane-side lens group GR, and has an aperture diaphragm and a lens LA that satisfies the above-described condition.

[0082] Alternatively, the telephoto optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF having a positive refractive power and an image-plane side lens group GR, with an aperture diaphragm positioned between the object-side lens group GF and the image-plane side lens group GR, and having a lens LA that satisfies the above-described condition.

[0083] This lens configuration makes it easier to reduce the overall length and light beam diameter, especially in telephoto optical systems, thereby miniaturizing and lightening the device.

[0084] Furthermore, in the telephoto optical system according to the present invention, when the optical system is magnified, it is desirable that the distance between at least the object-side lens group GF and the image-plane-side lens group GR changes during the magnification, and that lens LA is positioned in the object-side lens group GF and has a positive refractive power.

[0085] This configuration allows for effective correction of axial chromatic aberration and lateral chromatic aberration in both non-magnifying optical systems and in each magnification state of a magnifying optical system.

[0086] Furthermore, it is desirable that the following condition (3) be satisfied. (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0087] Conditional equation (3) defines a preferred range for the distance on the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm.

[0088] When the lower limit of condition (3) is exceeded, and the distance on the optical axis between the image plane side surface of lens LA located in the object-side lens group GF and the aperture diaphragm becomes small, it becomes difficult to effectively correct axial chromatic aberration and lateral chromatic aberration.

[0089] Furthermore, in the telephoto optical system according to the present invention, when the optical system is magnified, it is desirable that the distance between at least the object-side lens group GF and the image-plane-side lens group GR changes during the magnification, and that lens LA is positioned in the image-plane-side lens group GR and has negative refractive power.

[0090] This configuration allows for effective correction of chromatic aberration in both non-magnifying optical systems and in each magnification state of a magnifying optical system.

[0091] Furthermore, it is desirable that the following condition (4) be satisfied. (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance on the optical axis between the aperture diaphragm and the object-side surface of the lens LA located in the image-plane lens group GR, when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

[0092] Conditional equation (4) defines a preferred range for the distance on the optical axis between the aperture diaphragm and the object-side surface of lens LA, which is positioned in the image-plane lens group GR.

[0093] When the lower limit of condition (4) is exceeded, and the distance on the optical axis between the aperture diaphragm and the object-side surface of lens LA located in the image-plane lens group GR becomes small, it becomes difficult to effectively correct chromatic aberration.

[0094] Furthermore, in the telephoto optical system according to the present invention, when the optical system is magnified, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses in the optical system when it is focused at infinity in the most telephoto state, or when the optical system is not magnified, when it is focused at infinity, and it is desirable that lens LA is positioned in the object-side lens group GF and has a positive refractive power.

[0095] This configuration allows for effective correction of axial chromatic aberration and lateral chromatic aberration, both in optical systems that do not vary magnification and at the telephoto end of optical systems that do vary magnification.

[0096] Furthermore, in the telephoto optical system according to the present invention, when the optical system is magnified, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses in the optical system when it is focused at infinity in the most telephoto state, or when the optical system is not magnified, when it is focused at infinity, and it is desirable that lens LA is positioned in the image-plane-side lens group GR and has negative refractive power.

[0097] This configuration allows for effective correction of chromatic aberration in both non-magnifying optical systems and at the telephoto end of magnifying optical systems.

[0098] Furthermore, it is desirable that the telephoto optical system according to the present invention satisfies the following condition (5). (5) 0.40 > DFR / LT > 0.10 however, If the optical system does not change magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image plane-side lens group GR when the lens is focused at infinity. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the system is focused at infinity. When the optical system changes magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image-plane lens group GR when the object is in focus at infinity at its longest telephoto setting. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the optical system is in focus at infinity at its most telephoto setting.

[0099] Conditional equation (5) defines a preferred range for the air gap on the optical axis between the object-side lens group GF and the image plane-side lens group GR.

[0100] When the upper limit of condition (5) is exceeded, and the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR becomes large, it becomes difficult to effectively utilize the portion of the limited optical length occupied by this air gap for aberration correction, making it difficult to correct various aberrations such as distortion while achieving miniaturization of the overall length of the optical system.

[0101] When the lower limit of condition (5) is exceeded, and the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR becomes small, it becomes difficult to reduce the weight of the optical system because a large number of lenses will have to be placed at high ray heights.

[0102] Furthermore, by setting the upper limit of condition (5) to 0.36, the effects of the present invention can be achieved more reliably.

[0103] Furthermore, by setting the lower limit of condition (5) to 0.14, the effects of the present invention can be achieved more reliably.

[0104] Furthermore, in the telephoto optical system according to the present invention, if the optical system is magnified, it is desirable that the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis is lower than the height of the on-axial marginal rays passing through the optical surface closest to the object in the state where the optical system is focused at infinity in the most telephoto state, or if the optical system is not magnified, it is desirable that the height of the on-axial marginal rays passing through the optical surface closest to the object in the telephoto optical system from the optical axis is lower than the height of the on-axial marginal rays passing through the optical surface closest to the object in the telephoto optical system.

[0105] This configuration makes it easier to suppress the overall length of the optical system and the diameter of the aperture diaphragm, both in optical systems that do not change magnification and at the telephoto end of optical systems that do change magnification.

[0106] Furthermore, it is desirable that the telephoto optical system according to the present invention satisfies the following condition (6). (6) 0.70 > HS / HR1 > 0.20 however, If the optical system does not change magnification, HS: The height from the optical axis of the on-axial marginal rays passing through the aperture diaphragm when the focus is set to infinity. HR1: The height from the optical axis of the on-axial marginal ray passing through the optical surface closest to the object in the optical system when in focus at infinity. When the optical system changes magnification, HS: The height from the optical axis of the on-axial marginal rays passing through the aperture diaphragm when the focus is on infinity at the most telephoto setting. HR1: The height from the optical axis of the on-axial marginal ray passing through the optical surface closest to the object in the optical system when it is focused at infinity at its most telephoto setting.

[0107] Conditional equation (6) defines a preferred range for the ratio of the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis to the height of the on-axial marginal rays passing through the optical surface closest to the object in the optical system from the optical axis.

[0108] When the upper limit of condition (6) is exceeded, and the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis becomes relatively high, mechanisms such as variable diaphragms become larger, and it becomes difficult to keep the overall length of the optical system in check relative to the focal length.

[0109] When the lower limit of condition (6) is exceeded, and the height of the on-axial marginal rays passing through the aperture diaphragm from the optical axis becomes relatively low, a surface with extremely strong refractive power is required to strongly refract the on-axial marginal rays. This worsens various aberrations such as spherical aberration, and performance degradation due to eccentricity and other factors becomes more likely.

[0110] Furthermore, by setting the upper limit of condition (6) to 0.60, the effects of the present invention can be achieved more reliably.

[0111] Furthermore, by setting the lower limit of conditional equation (6) to 0.25, the effects of the present invention can be achieved more reliably.

[0112] The following describes the lens configuration, numerical examples, and corresponding values ​​for conditional expressions for each embodiment of the wide-angle to standard type optical system and the telephoto type optical system according to the present invention. In the following description, the lens configuration will be described in order from the object side to the image plane side.

[0113] In the [surface data], the surface number is the number of the lens surface or aperture diaphragm counted from the object side, r is the radius of curvature of each lens surface, d is the spacing between each lens surface, nd is the refractive index for the d line (wavelength 587.56 nm), vd is the Abbe number for the d line, and θgF indicates the partial dispersion ratio of the g line (wavelength 435.84 nm) and the F line (wavelength 486.13 nm).

[0114] The asterisk (*) next to the surface number indicates that the lens surface shape is aspherical. BF indicates the back focus, and the object surface distance indicates the distance from the subject to the first lens surface.

[0115] The (diaphragm) next to the face number indicates that an aperture diaphragm is located at that position. The radius of curvature relative to the plane or aperture diaphragm is indicated with ∞ (infinity).

[0116] The [Aspherical Data] section shows the values ​​of the coefficients that give the aspherical shape of the lens surface marked with an asterisk (*) in the [Surface Data] section. The shape of the aspherical surface is expressed by the following formula. In the following formula, y represents the displacement from the optical axis in the direction perpendicular to the optical axis, z represents the displacement (sag) in the direction of the optical axis from the intersection of the aspherical surface and the optical axis, r represents the radius of curvature of the reference sphere, and K represents the conic coefficient. The 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, 15th, and 16th order aspherical coefficients are represented by A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, and A16, respectively.

[0117]

number

[0118] The [Various Data] section shows the values ​​for focal length, etc., for each focal length state or each shooting distance focus state.

[0119] The [Variable Interval Data] section shows the variable interval and BF values ​​for each focal length state or each shooting distance focus state.

[0120] The [Lens Group Data] shows the number of the object-side surface in each lens group and the combined focal length of the entire group.

[0121] Furthermore, in the aberration diagrams corresponding to each embodiment, d, g, and C represent the d line, g line, and C line, respectively, and △S and △M represent the sagittal image plane and meridional image plane, respectively.

[0122] In addition, for all the specifications listed below, the units of focal length f, radius of curvature r, lens plane spacing d, and other lengths are millimeters (mm) unless otherwise specified. However, since equivalent optical performance can be obtained in both proportional magnification and proportional reduction in the optical system, this is not the only unit of measurement. [Examples]

[0123] Figure 1 is a lens configuration diagram of the variable magnification optical system of Embodiment 1 of the present invention.

[0124] The variable magnification optical system of Example 1 consists of, in order from the object 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. When magnifying from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases and then decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. The sixth lens group G6 is fixed to the image plane during magnification.

[0125] The combined group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF, the combined group of the third lens group G3 to the sixth lens group G6 corresponds to the image plane-side lens group GR, and the second lens group G2 corresponds to the lens group GFA which includes lens LA.

[0126] The combined group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF, the combined group of the third lens group G3 to the sixth lens group G6 corresponds to the image plane-side lens group GR, and the second lens group G2 corresponds to the lens group GFA which includes lens LA.

[0127] The aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3.

[0128] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 and a biconvex lens L2, both with their convex surfaces facing the object, and a positive meniscus lens L3 with its convex surface facing the object.

[0129] The second lens group G2 consists of a negative meniscus lens L4 with its convex surface facing the object, a cemented lens consisting of a biconcave lens L5 and a biconvex lens L6, a biconvex lens L7, and a negative meniscus lens L8 with its convex surface facing the image plane, with the lens surfaces on both sides of the negative meniscus lens L4 having a predetermined aspherical shape. The negative meniscus lens L8 corresponds to lens LA in this invention.

[0130] The third lens group G3 consists of a positive meniscus lens L9 with its convex surface facing the body, in order from the object side; a cemented lens consisting of a positive meniscus lens L10 with its convex surface facing the object and a negative meniscus lens L11 with its convex surface facing the object; and a cemented lens consisting of a negative meniscus lens L12 with its convex surface facing the object and a positive meniscus lens L13 with its convex surface facing the object. The lens surfaces on both sides of the positive meniscus lens L9 have a predetermined aspherical shape. The positive meniscus lens L13 corresponds to lens LA in this invention.

[0131] The fourth lens group G4 consists of a cemented lens comprising a negative meniscus lens L14 and a biconvex lens L15, with their convex surfaces facing the object side in order from the object side, and a biconvex lens L16, the lens surfaces on both sides of the biconvex lens L16 having a predetermined aspherical shape. The biconvex lens L15 corresponds to lens LA in this invention.

[0132] The fifth lens group G5 consists solely of negative meniscus lenses L17, with their convex surfaces facing the object side, starting from the object side. When focusing from an infinity object distance to a close distance, the entire fifth lens group G5 moves towards the image plane.

[0133] The sixth lens group G6 consists of a biconvex lens L18, a biconcave lens L19, and a negative meniscus lens L20 with its convex surface facing the image plane, and the lens surfaces on both sides of the negative meniscus lens L20 have a predetermined aspherical shape.

[0134] The specifications of the optical system according to Example 1 are shown below. Numerical Example 1 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1 672.5318 2.5000 1.92286 20.88 0.638840 2 223.7090 8.2551 1.55032 75.50 0.539881 3 -354.6280 0.1500 4 72.3861 8.5434 1.75500 52.32 0.547242 5 225.2088 (d5) 6* 212.1689 2.3000 1.77250 49.50 0.551804 7* 23.4631 10.4743 8 -37.5554 1.6635 1.59282 68.62 0.544009 9 26.8746 7.2057 1.75500 52.32 0.547242 10 -259.9052 0.1500 11 770.2718 3.3191 2.00100 29.13 0.599373 12 -100.6859 3.1153 13 -29.5029 0.9000 1.41390 100.82 0.533605 14 -80.2315 (d14) 15 (aperture) ∞ 1.5000 16* 54.1542 3.3572 1.55332 71.68 0.540167 17* 133.5316 0.1500 18 35.6379 5.4355 1.92286 20.88 0.638840 19 100.5624 1.1000 1.77047 29.74 0.594996 20 38.9981 0.3135 21 39.6115 1.1000 1.85451 25.15 0.610160 22 23.3180 7.4617 1.41390 100.82 0.533605 23 103.9434 (d23) 24 68.3190 1.2000 1.85451 25.15 0.610160 25 31.5332 7.7102 1.41390 100.82 0.533605 26 -151.3755 0.2323 27* 34.4957 10.1222 1.59201 67.02 0.535765 28* -38.5287 (d28) 29 84.1341 0.9000 1.91082 35.25 0.582104 30 29.1111 (d30) 31 139.8664 6.4702 2.00100 29.13 0.599373 32 -48.4533 0.1500 33 -62.5586 0.9000 1.73037 32.23 0.589819 34 153.1720 4.9045 35* -47.2352 1.3500 1.58313 59.46 0.540428 36* -145.3412 (BF) Image plane ∞ [Aspherical data] 6 sides 7 sides 16 sides 17 sides K 0.00000 0.00000 0.00000 0.00000 A4 2.51576E-07 -2.94360E-06 -3.49364E-06 7.49274E-08 A6 1.94291E-08 1.97402E-08 1.20715E-08 1.57632E-08 A8 -7.87263E-11 -2.23590E-11 -9.32398E-12 -7.62943E-12 A10 1.86394E-13 -8.03218E-14 -3.44187E-14 -3.63402E-14 A12 -2.35091E-16 3.29341E-16 0.00000E+00 0.00000E+00 A14 1.29558E-19 0.00000E+00 0.00000E+00 0.00000E+00 Pages 27, 28, 35, and 36 K 0.00000 0.00000 0.00000 0.00000 A4 -7.54571E-06 5.24520E-06 6.33827E-07 2.39126E-06 A6 -1.04713E-09 -9.06910E-09 -3.85594E-08 -4.11777E-08 A8 2.04182E-12 1.12469E-11 4.89128E-12 3.29571E-11 A10 -1.86264E-14 -1.87968E-14 5.03597E-14 -9.46789E-15 A12 2.67430E-17 1.57087E-17 -6.61740E-17 9.29198E-18 A14 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 [Various Data] Zoom ratio 2.34 Wide-angle, Medium, Telephoto Focal length 28.90 49.99 67.75 F-number 2.07 2.07 2.07 Full angle of view 2ω 76.74 45.57 33.8 Image height Y 21.63 21.63 21.63 Lens length: 169.15, 171.89, 184.16 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.5000 17.2434 31.2233 d14 26.7966 6.2404 2.0000 d23 3.9900 2.5649 1.5000 d28 1.9500 3.6671 2.7564 d30 10.6818 17.9447 22.4440 BF 21.2980 21.2980 21.2980 [Lens group data] Group starting plane focal length G1 1 117.28 G2 6 -29.60 G3 15 79.54 G4 24 31.19 G5 29 -49.26 G6 31 262.47 [Examples]

[0135] Figure 8 is a lens configuration diagram of the variable magnification optical system of Embodiment 2 of the present invention.

[0136] The variable magnification optical system of Example 2 consists of, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. When magnifying from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

[0137] The first lens group G1 corresponds to the lens group GFA, which includes the object-side lens group GF and lens LA, and the combined group of the second lens group G2 to the fourth lens group G4 corresponds to the image plane-side lens group GR.

[0138] The combined group of the first lens group G1 to the third lens group G3 corresponds to the object-side lens group GF, the first lens group G1 corresponds to the lens group GFA which includes lens LA, and the fourth lens group G4 corresponds to the image plane-side lens group GR.

[0139] The aperture diaphragm S is positioned between the third lens group G3 and the fourth lens group G4.

[0140] The first lens group G1 consists of, in order from the object side, a negative meniscus lens L1 with its convex surface facing the object side, a negative meniscus lens L2 with its convex surface facing the object side, a biconcave lens L3, and a positive meniscus lens L4 with its convex surface facing the object side. The lens surfaces on both sides of the negative meniscus lens L1 have a predetermined aspherical shape. The biconcave lens L3 corresponds to lens LA in this invention.

[0141] The second lens group G2 consists solely of a cemented lens comprising a negative meniscus lens L5 with its convex surface facing the object, and a biconvex lens L6. The second lens group G2 moves towards the image plane when focusing from an object distance of infinity to a close distance.

[0142] The third lens group G3 consists of, in order from the object side, a negative meniscus lens L7 with a convex surface facing the image plane, and a cemented lens consisting of a negative meniscus lens L8 with a convex surface facing the object and a biconvex lens L9, with the lens surfaces on both sides of the negative meniscus lens L7 having a predetermined aspherical shape.

[0143] The fourth lens group G4 consists of, in order from the object side, a biconvex lens L10, a cemented lens consisting of a negative meniscus lens L11 and a biconvex lens L12 with their convex surfaces facing the object side, a cemented lens consisting of a biconcave lens L13 and a positive meniscus lens L14 with its convex surface facing the object side, a cemented lens consisting of a negative meniscus lens L15 and a biconvex lens L16 with their convex surfaces facing the object side, and a biconcave lens L17, with the lens surfaces on both sides of the biconcave lens L17 having a predetermined aspherical shape. The biconvex lens L10 corresponds to lens LA in this invention.

[0144] The specifications of the optical system according to Example 2 are shown below. Numerical Example 2 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1* 84.2242 3.2000 1.69350 53.18 0.548185 2* 24.7641 12.2180 3 54.3275 1.7000 1.88100 40.14 0.569968 4 19.2421 14.3104 5 -46.8729 1.2500 1.41390 100.82 0.533605 6 51.8469 0.2858 7 39.4670 3.5474 1.86966 20.02 0.643332 8 102.9982 (d8) 9 56.3987 0.8000 2.00069 25.46 0.613492 10 21.2660 5.0673 1.73037 32.23 0.589819 11 -78.1393 (d11) 12* -38.1015 1.1054 1.85135 40.10 0.569406 13* -336.5447 0.1500 14 40.1135 0.9000 1.92286 20.88 0.638840 15 24.4027 6.0529 1.71736 29.50 0.603381 16 -132.0011 (d16) 17 (aperture) ∞ 1.2400 18 39.9349 5.4590 1.41390 100.82 0.533605 19 -61.8782 0.1500 20 28.0224 0.9000 1.77047 29.74 0.594996 21 16.3856 8.6036 1.55032 75.50 0.539881 22 -111.2533 2.4420 23 -52.8314 0.9000 1.95375 32.32 0.590002 24 18.5517 4.9231 1.92286 20.88 0.638840 25 128.8227 0.1500 26 23.6476 0.9000 1.90043 37.37 0.576542 27 15.1999 9.9268 1.49700 81.61 0.538747 28 -33.5096 0.1500 29* -300.0000 1.3000 1.80610 40.73 0.569264 30* 53.0620 (BF) Image plane ∞ [Aspherical data] Page 1 Page 2 Page 12 Page 13 K 0.00000 -0.59024 0.00000 0.00000 A4 3.14115E-05 3.57246E-05 5.87260E-07 1.33089E-06 A6 -9.30287E-08 -2.21252E-08 9.54963E-08 8.27963E-08 A8 1.78995E-10 -4.09995E-10 -1.05725E-09 -9.67519E-10 A10 -2.19064E-13 1.97208E-12 5.82638E-12 5.47255E-12 A12 1.65913E-16 -4.24159E-15 -1.13951E-14 -1.13990E-14 A14 -7.04547E-20 4.49697E-18 0.00000E+00 0.00000E+00 A16 1.29362E-23 -1.89109E-21 0.00000E+00 0.00000E+00 Pages 29 and 30 K 0.00000 0.00000 A4 -1.36584E-05 1.32575E-05 A6 -4.65492E-07 -4.66888E-07 A8 1.25901E-08 1.24064E-08 A10 -1.70606E-10 -1.63327E-10 A12 1.26500E-12 1.16770E-12 A14 -4.79106E-15 -4.29296E-15 A16 7.22467E-18 6.28893E-18 [Various Data] Zoom ratio 1.87 Wide-angle, Medium, Telephoto Focal length 12.40 17.00 23.15 F-number 2.92 2.92 2.92 Full picture angle 2ω 122.82 103.12 84.4 Image height Y 21.63 21.63 21.63 Overall lens length 148.00 142.30 141.41 [Variable interval data] Wide angle Medium Telephoto d0 ∞ ∞ ∞ d8 19.9537 9.4612 3.1500 d11 6.5022 9.0635 7.8411 d16 11.4721 5.1519 1.4000 BF 22.4402 30.9877 41.3850 [Lens group data] Group Starting surface Focal length G1 1 -16.16 G2 9 70.11 G3 12 1503.78 G4 17 43.21

Example

[0145] Figure 15 is a lens configuration diagram of the optical system of Example 3 of the present invention.

[0146] The optical system of Example 3 is composed of, in order from the object side, a first lens group G1 with a negative refractive power, a second lens group G2 with a positive refractive power, a third lens group G3 with a positive refractive power, and a fourth lens group G4 with a positive refractive power. [[ID=�6]]

[0147] The first lens group G1 corresponds to a lens group GFA including an object-side lens group GF and a lens LA, and the combined groups of the second lens group G2 to the fourth lens group G4 respectively correspond to an image-side lens group GR.

[0148] The combined group of the first lens group G1 to the third lens group G3 corresponds to an object-side lens group GF, the first lens group G1 corresponds to a lens group GFA including a lens LA, and the fourth lens group G4 corresponds to an image-side lens group GR. [

[0149] An aperture stop S is disposed between the third lens group G3 and the fourth lens group G4.

[0150] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a convex surface facing the object side, a cemented lens composed of a biconvex lens L4 and a biconcave lens L5, and the lens surfaces on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. The biconcave lens L5 corresponds to the lens LA in the present invention.

[0151] The second lens group G2 is composed only of a cemented lens consisting of a negative meniscus lens L6 with a convex surface facing the object side and a positive meniscus lens L7 with a convex surface facing the object side. The second lens group G2 moves toward the image plane side during focusing from an infinite object distance to a short distance.

[0152] The third lens group G3 is composed of, in order from the object side, a cemented lens consisting of a biconvex lens L8 and a negative meniscus lens L9 with a convex surface facing the image side, and a cemented lens consisting of a biconcave lens L10 and a biconvex lens L11.

[0153] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L12, a cemented lens consisting of a negative meniscus lens L13 with a convex surface facing the object side and a biconvex lens L14, a cemented lens consisting of a biconcave lens L15 and a biconvex lens L16, a negative meniscus lens L17 with a convex surface facing the object side, and a negative meniscus lens L18 with a convex surface facing the image plane side, and the lens surfaces on both sides of the negative meniscus lens L18 have a predetermined aspherical shape. The biconvex lens L12 corresponds to the lens LA in the present invention.

[0154] [[ID=二十]]The specifications of the optical system according to Example 3 are shown below. Numerical Example 3 Unit: mm [Surface Data] Surface No. r d nd vd θgF Object surface ∞ (d0) 1* 557.0263 3.2000 1.69350 53.18 0.548185 2 23.1636 8.4495 3 40.4452 1.7000 1.59282 68.62 0.544009 4 20.6555 8.6089 5* 43.0482 1.8800 1.59201 67.02 0.535765 6* 18.9983 1.8639 7 27.1416 8.9531 1.85451 25.15 0.610160 8 -749.3128 2.9989 1.41390 100.82 0.533605 9 19.3594 (d9) 10 33.4363 0.7000 2.00069 25.46 0.613492 11 16.7938 4.8268 1.75211 25.05 0.619087 12 87.8644 (d12) 13 31.9306 5.7987 1.90043 37.37 0.576542 14 -34.7272 0.8000 1.92286 20.88 0.638840 15 -55.6678 0.6525 16 -110.7050 0.8000 2.00100 29.13 0.599373 17 16.4803 5.5833 1.59349 67.00 0.536541 18 -152.6016 2.1784 19 (aperture) ∞ 2.0527 20 22.4831 5.4394 1.41390 100.82 0.533605 21 -48.0693 0.1511 22 42.2433 0.8000 1.88300 40.80 0.565434 23 13.5353 6.9022 1.55032 75.50 0.539881 24 -63.8490 1.3077 25 -27.4669 0.8000 1.73037 32.23 0.589819 26 24.7307 7.2312 1.92286 20.88 0.638840 27 -35.8817 0.1500 28 41.0230 0.8000 1.85451 25.15 0.610160 29 28.1086 4.4917 30* -54.3848 1.3000 1.69350 53.20 0.546484 31* -106.5247 (BF) Image plane ∞ [Aspherical surface] 1 side, 5 sides, 6 sides, 30 sides K 0.00000 0.00000 0.00000 0.00000 A3 0.00000E+00 -1.65156E-05 -2.04166E-05 0.00000E+00 A4 1.30938E-05 1.53574E-06 -5.39138E-06 -1.78785E-05 A5 0.00000E+00 -1.68596E-05 -1.65584E-05 0.00000E+00 A6 -1.98839E-08 2.19398E-06 2.01360E-06 2.78978E-07 A7 0.00000E+00 -7.59058E-08 -4.09560E-08 0.00000E+00 A8 2.41619E-11 -1.94496E-09 -5.42316E-09 -8.51812E-09 A9 0.00000E+00 8.67238E-11 2.16135E-10 0.00000E+00 A10 -1.82623E-14 5.05299E-12 7.74806E-12 7.90301E-11 A11 0.00000E+00 -5.93823E-14 -4.60896E-13 0.00000E+00 A12 7.84092E-18 -1.38773E-14 -1.86374E-14 -2.84505E-13 A13 0.00000E+00 3.11908E-16 9.51558E-16 0.00000E+00 A14 -1.48833E-21 5.51021E-18 1.13424E-16 1.96430E-16 A15 0.00000E+00 9.06185E-20 -7.86519E-18 0.00000E+00 A16 1.08206E-26 -9.87459E-21 1.18780E-19 6.46300E-19 31st surface K 0.00000 A3 0.00000E+00 A4 1.60382E-05 A5 0.00000E+00 A6 7.86467E-08 A7 0.00000E+00 A8 -3.28905E-09 [[ID=�0]]A9 0.00000E+00 A10 2.08144E-11 A11 0.00000E+00 A12 4.01215E-14 A13 0.00000E+�0 A14 -6.81380E-16 A15 0.00000E+00 A16 1.52268E-18 [Various data] INF 245mm Focal length 14.47 13.88 F-number 2.07 2.07 Full angle of view 2ω 114.30 114.11 Image height Y 21.63 21.63 Lens length 128.00 128.00 [Variable interval data] INF 245mm d0 ∞ 117.0000 d9 9.9046 14.0404 d11 7.6755 3.5397 BF 20.0000 20.0000 [Lens group data] Group starting plane focal length G1 1 -16.90 G2 10 139.44 G3 13 60.46 G4 20 40.88 [Examples]

[0155] Figure 20 is a lens configuration diagram of the optical system according to Embodiment 4 of the present invention.

[0156] The optical system of Example 4 consists of, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power.

[0157] The first lens group G1 corresponds to the lens group GFA, which includes the object-side lens group GF and lens LA, and the combined group of the second lens group G2 to the fourth lens group G4 corresponds to the image plane-side lens group GR.

[0158] The combined group of the first lens group G1 to the third lens group G3 corresponds to the object-side lens group GF, the first lens group G1 corresponds to the lens group GFA which includes lens LA, and the fourth lens group G4 corresponds to the image plane-side lens group GR.

[0159] The aperture diaphragm S is positioned between the third lens group G3 and the fourth lens group G4.

[0160] The first lens group G1 consists of, in order from the object side, a negative meniscus lens L1 with its convex surface facing the object, a negative meniscus lens L2 with its convex surface facing the object, a negative meniscus lens L3 with its convex surface facing the object, and a cemented lens consisting of a biconvex lens L4 and a biconcave lens L5. The object-side lens surface of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspherical shape. The biconcave lens L5 corresponds to lens LA in this invention.

[0161] The second lens group G2 consists only of a cemented lens comprising a negative meniscus lens L6 with its convex surface facing the object and a positive meniscus lens L7 with its convex surface facing the object. The second lens group G2 moves toward the image plane when focusing from an object distance of infinity to a close distance.

[0162] The third lens group G3 consists of, in order from the object side, a cemented lens comprising a biconvex lens L8 and a negative meniscus lens L9 with its convex surface facing the image side, and a cemented lens comprising a biconcave lens L10 and a positive meniscus lens L11 with its convex surface facing the object side.

[0163] The fourth lens group G4 consists, in order from the object side, of a biconvex lens L12, a cemented lens consisting of a negative meniscus lens L13 and a biconvex lens L14 with their convex surfaces facing the object side, a cemented lens consisting of a biconcave lens L15 and a biconvex lens L16, a negative meniscus lens L17 with its convex surface facing the object side, and a negative meniscus lens L18 with its convex surface facing the image plane side, with the lens surfaces on both sides of the negative meniscus lens L18 having a predetermined aspherical shape. The biconvex lens L12 corresponds to lens LA in this invention.

[0164] The specifications of the optical system according to Example 4 are shown below. Numerical Example 4 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1* 345.5736 3.2000 1.69350 53.18 0.548185 2 23.2818 8.9032 3 43.3044 1.7000 1.59282 68.62 0.544009 4 20.2688 8.6138 5* 46.6429 1.8800 1.59201 67.02 0.535765 6* 18.2799 2.2099 7 26.6989 9.1000 1.85451 25.15 0.610160 8 -193.5728 3.0000 1.42537 97.75 0.534212 9 18.8420 (d9) 10 31.1125 0.7000 2.00069 25.46 0.613492 11 16.8217 4.6143 1.68430 26.81 0.623031 12 121.3655 (d12) 13 32.2912 5.9158 1.91082 35.25 0.582104 14 -30.5864 0.8000 1.92286 20.88 0.638840 15 -55.8697 0.1500 16 -252.3463 0.8000 2.00100 29.13 0.599373 17 15.3145 5.3640 1.59349 67.00 0.536541 18 556.5564 2.5846 19 (aperture) ∞ 2.3551 20 21.5784 5.4219 1.42537 97.75 0.534212 21 -48.3957 0.1500 22 41.6151 0.8000 1.88300 40.80 0.565434 23 13.0308 7.2226 1.55032 75.50 0.539881 24 -53.9843 1.1910 25 -27.1893 0.8000 1.73037 32.23 0.589819 26 24.3547 7.4144 1.92286 20.88 0.638840 27 -34.4511 0.1500 28 49.2619 0.8000 1.85451 25.15 0.610160 29 30.3051 4.2228 30* -61.9600 1.3000 1.69350 53.20 0.546484 31* -140.0670 (BF) Image plane ∞ [Aspherical surface] 1 side, 5 sides, 6 sides, 30 sides K 0.00000 0.00000 0.00000 0.00000 A3 0.00000E+00 -4.29394E-05 -4.47699E-05 0.00000E+00 A4 1.31973E-05 -3.23917E-06 -1.07631E-05 -1.48304E-05 A5 0.00000E+00 -1.55812E-05 -1.52773E-05 0.00000E+00 A6 -2.12142E-08 2.25385E-06 1.97098E-06 -2.75773E-08 A7 0.00000E+00 -8.26148E-08 -3.01272E-08 0.00000E+00 A8 2.59364E-11 -1.88418E-09 -6.18964E-09 -2.48320E-09 A9 0.00000E+00 8.03602E-11 1.88741E-10 0.00000E+00 A10 -2.02754E-14 4.75377E-12 7.60157E-12 -1.06682E-11 A11 0.00000E+00 -4.51040E-14 -3.91478E-13 0.00000E+00 A12 1.09327E-17 -1.25773E-14 -1.49127E-14 5.33561E-13 A13 0.00000E+00 3.82153E-16 1.10177E-15 0.00000E+00 A14 -4.19867E-21 5.71539E-18 1.14822E-16 -3.53995E-15 A15 0.00000E+00 -1.55740E-19 -8.29782E-18 0.00000E+00 A16 8.60486E-25 -8.89043E-21 9.21510E-20 7.21968E-18 31 pages K 0.00000 A3 0.00000E+00 A4 2.28967E-05 A5 0.00000E+00 A6 -1.93440E-07 A7 0.00000E+00 A8 5.22259E-10 A9 0.00000E+00 A10 -2.27781E-11 A11 0.00000E+00 A12 3.91172E-13 A13 0.00000E+00 A14 -2.16287E-15 A15 0.00000E+00 A16 3.92770E-18 [Various Data] INF 230mm Focal length 14.00 13.39 F-number 2.07 2.07 Full angle of view 2ω 116.02 115.92 Image height Y 21.63 21.63 Lens length 128.00 128.00 [Variable interval data] INF 245mm d0 ∞ 102.0000 d9 9.1032 12.8682 d11 7.5336 3.7685 BF 20.0000 20.0000 [Lens group data] Group starting plane focal length G1 1 -16.09 G2 10 121.93 G3 13 67.06 G4 20 38.19 [Examples]

[0165] Figure 25 is a lens configuration diagram of the variable magnification optical system of Example 5 at the wide-angle end at infinity. Example 5 is an embodiment of the variable magnification optical system according to the present invention.

[0166] The variable magnification optical system of Example 5 consists of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with positive refractive power, a seventh lens group G7 with negative refractive power, and an eighth lens group G8 with negative refractive power. An aperture diaphragm S is positioned between the fifth lens group G5 and the sixth lens group G6.

[0167] The first lens group G1 corresponds to the object-side lens group GF in claim 1, and the combined group of the second lens group G2 to the eighth lens group G8 corresponds to the image plane-side lens group GR in claim 1.

[0168] The combined group of the first lens group G1 to the fifth lens group G5 corresponds to the object-side lens group GF, and the combined group of the sixth lens group G6 to the eighth lens group G8 corresponds to the image plane-side lens group GR.

[0169] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 and the eighth lens group G8 are fixed relative to the image plane, the first lens group G1 moves toward the object, the second lens group G2 moves toward the image, and the fourth lens group G4 to the seventh lens group G7 each move toward the object. The distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases.

[0170] The first lens group G1 consists of, in order from the object side, a negative meniscus lens L1 with its convex surface facing the object, a positive meniscus lens L2 with its convex surface facing the object, and a positive meniscus lens L3 with its convex surface facing the object. The positive meniscus lens L3 corresponds to lens LA in this invention.

[0171] The second lens group G2 consists only of cemented lenses, which are a biconvex lens L4 and a biconcave lens L5, in that order from the object side.

[0172] The third lens group G3 consists of, in order from the object side, a biconvex lens L6, a cemented lens consisting of a biconcave lens L7 and a positive meniscus lens L8 with its convex surface facing the object, a biconcave lens L9, and a cemented lens consisting of a biconcave lens L10 and a biconvex lens L11. Furthermore, by moving the biconcave lens L9 and the cemented lens consisting of the biconcave lens L10 and the biconvex lens L11 as a single unit perpendicular to the optical axis, it is also possible to make them function as vibration-damping groups.

[0173] The fourth lens group G4 consists of a biconvex lens L12 and a cemented lens comprising a biconvex lens L13 and a negative meniscus lens L14 with its convex surface facing the image side, in that order from the object side.

[0174] The fifth lens group G5 consists of a biconvex lens L15, a negative meniscus lens L16 with its convex surface facing the object, and a cemented lens consisting of a biconvex lens L17, in that order from the object side.

[0175] The sixth lens group G6 consists solely of cemented lenses: a biconvex lens L18 and a negative meniscus lens L19 with its convex surface facing the image side, in that order from the object side. When focusing from an infinity object distance to a close distance, the entire sixth lens group G6 moves towards the object side.

[0176] The seventh lens group G7 consists of a cemented lens comprising a positive meniscus lens L20 and a biconcave lens L21, with their convex surfaces facing the image side in order from the object side, and a cemented lens comprising a positive meniscus lens L22 with its convex surface facing the image side and a negative meniscus lens L23 with its convex surface facing the image side. The negative meniscus lens L23 corresponds to lens LA in this invention.

[0177] The eighth lens group G8 consists of a cemented lens comprising a biconvex lens L24 and a biconcave lens L25, in order from the object side, and a negative meniscus lens L26 with its convex surface facing the image side.

[0178] The specifications of the optical system according to Example 5 are shown below. Numerical Example 5 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1 229.5367 2.9999 1.61340 44.27 0.563261 2 113.6783 0.3042 3 113.6776 9.7491 1.49700 81.61 0.538747 4 1554.0767 0.4000 5 155.4355 7.6390 1.41390 100.82 0.533605 6 2378.2886 (d6) 7 149.1765 5.4165 1.80518 25.46 0.615570 8 -243.4151 1.4497 1.92286 20.88 0.638840 9 615.6485 (d9) 10 103.0359 3.9954 1.53172 48.84 0.562956 11 -2868.5651 8.6239 12 -576.2228 1.0000 1.95375 32.32 0.590421 13 49.3785 3.3171 1.80809 22.76 0.628525 14 110.3663 5.8425 15 -1447.6315 0.8985 1.78590 44.20 0.563036 16 69.9168 3.4207 17 -53.3084 0.8976 1.76385 48.49 0.558845 18 70.2262 3.5785 1.85451 25.15 0.610160 19 -508.3408 (d19) 20 173.4815 2.8197 1.76385 48.49 0.558845 21 -121.8628 0.3000 22 44.0638 6.5847 1.41390 100.82 0.533605 23 -53.5108 0.8996 1.91082 35.25 0.582104 24 -566.9645 (d24) 25 69.1711 3.8855 1.72825 28.32 0.607404 26 -115.6877 0.3000 27 434.2774 0.8997 28 29.0131 5.2716 1.91082 35.25 0.582104 29 -794.7897 3.0000 1.41390 100.82 0.533605 30 (aperture) ∞ (d30) 31 60.0072 4.5217 1.74077 27.76 0.607621 32 -49.5858 0.8000 1.94595 17.98 0.654432 33 -186.1592 (d33) 34 -250.7606 1.7524 1.82166 24.04 0.623642 35 -58.2923 0.8998 1.90525 35.04 0.584723 36 52.8406 9.4298 37 -281.2955 6.0996 1.61340 44.27 0.563261 38 -25.9751 0.9999 1.41390 100.82 0.533605 39 -305.6963 (d39) 40 55.5004 7.9523 1.61340 44.27 0.563261 41 -32.0309 0.9998 1.53775 74.70 0.539232 42 148.3945 13.9898 43 -42.9000 0.8999 1.95375 32.32 0.590421 44 -258.7263 37.0956 45 ∞ 2.5000 1.51680 64.20 0.534177 46 ∞ (BF) Image plane ∞ [Various Data] Zoom ratio 3.74 Wide-angle, Medium, Telephoto Focal length 154.50 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.68 8.65 4.18 Image height Y 21.63 21.63 21.63 Lens length: 280.00 333.16 380.00 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d6 17.0583 74.2825 131.3315 d9 16.2732 12.2077 2.0000 d19 33.7924 21.0378 2.0000 d24 11.4042 4.8495 2.1386 d30 16.2626 26.5499 44.8691 d33 10.7755 9.2044 3.3000 d39 2.0000 12.5930 21.9269 BF 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 263.4314 G2 7 289.6265 G3 10 -34.6015 G4 20 76.7664 G5 25 367.2863 G6 31 75.5253 G7 34 -78.2659 G8 40 -203.8433 [Examples]

[0179] Figure 32 is a lens configuration diagram of the optical system of Example 6 at infinity. Example 6 is an example of a non-magnifying optical system according to the present invention.

[0180] The optical system of Example 6 consists of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, and a third lens group G3 with negative refractive power. An aperture diaphragm S is positioned between the second lens group G2 and the third lens group G3.

[0181] The combined group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF of claim 1, and the third lens group G3 corresponds to the image plane-side lens group GR of claim 1.

[0182] The first lens group G1 is composed of, in order from the object side, a biconvex lens L1, a positive meniscus lens L2 with its convex surface facing the object, a biconcave lens L3, a negative meniscus lens L4 with its convex surface facing the object, and a cemented lens consisting of a positive meniscus lens L5 with its convex surface facing the object. The biconvex lens L1 and the positive meniscus lens L2 correspond to lens LA in this invention.

[0183] The second lens group G2 consists solely of a cemented lens comprising a negative meniscus lens L6 with its convex surface facing the object and a positive meniscus lens L7 with its convex surface facing the object. When focusing from an object distance of infinity to a close distance, the entire second lens group G2 moves toward the image plane.

[0184] The third lens group G3 consists of a cemented lens comprising a biconvex lens L8 and a biconcave lens L9, a cemented lens comprising a biconvex lens L10 and a biconcave lens L11, a biconcave lens L12, a cemented lens comprising a biconvex lens L13 and a negative meniscus lens L14 with its convex surface facing the image plane, a cemented lens comprising a negative meniscus lens L15 with its convex surface facing the object and a biconvex lens L16, and a negative meniscus lens L17 with its convex surface facing the image plane. The negative meniscus lens L15 corresponds to lens LA in this invention. Furthermore, the cemented lens comprising the biconvex lens L10 and the biconcave lens L11 and the biconcave lens L12 within the third lens group G3 can also function as a vibration isolation group by moving them together in a direction perpendicular to the optical axis.

[0185] The specifications of the optical system according to Example 6 are shown below. Numerical Example 6 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1 153.4863 22.0000 1.42537 97.75 0.534212 2 -789.8781 18.5397 3 128.1087 16.6088 1.41390 100.82 0.533605 4 1068.1574 3.4364 5 -1078.9331 4.5000 1.65160 58.54 0.538879 6 402.3975 42.5469 7 84.3943 2.5000 1.88300 40.80 0.565434 8 54.8662 0.1500 9 54.2574 17.6556 1.43700 95.10 0.533516 10 341.7838 (d10) 11 379.2478 2.0000 1.88100 40.14 0.569968 12 96.1649 4.3878 1.92286 20.88 0.638840 13 125.4389 (d13) 14 (aperture) ∞ 3.0000 15 47.1304 7.6236 1.95375 32.32 0.590421 16 -136.1010 0.9500 1.84666 23.78 0.619078 17 42.9084 6.2385 18 152.3712 5.0488 1.85451 25.15 0.610160 19 -73.8150 0.9500 1.76385 48.49 0.558845 20 58.7382 3.4228 21 -138.9520 0.9500 1.69680 55.46 0.542469 22 70.9139 3.0000 23 74.4387 8.7925 1.68893 31.16 0.598858 24 -34.5131 0.9500 1.95375 32.32 0.590421 25 -181.5318 12.3412 26 85.6865 1.1000 1.41390 100.82 0.533605 27 34.6404 13.2138 1.48749 70.44 0.530491 28 -64.2408 14.0691 29 -40.8218 1.0001 1.95375 32.32 0.590421 30 -66.9955 42.4101 31 ∞ 2.4000 1.51680 64.17 0.534826 32 ∞ (BF) Image plane ∞ [Various Data] INF 2675mm Focal length 388.00 287.57 F-number 2.88 2.92 Full angle of view 2ω 6.32 4.62 Image height Y 21.63 21.63 Lens length 330.00 330.00 [Variable interval data] INF 2675mm d0 ∞ 2345.0001 d10 3.7975 31.5887 d13 63.4170 35.6257 BF 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 199.08 G2 11 -220.49 G3 14 -470.94 [Examples]

[0186] Figure 37 is a lens configuration diagram of the optical system of Example 7 at infinity. Example 7 is an example of a non-magnifying optical system according to the present invention.

[0187] The optical system of Example 7 consists of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, and a third lens group G3 with positive refractive power. An aperture diaphragm S is positioned between the first lens group G1 and the second lens group G2.

[0188] The combined group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF in claim 1, and the third lens group G3 corresponds to the image plane-side lens group GR in claim 1.

[0189] The first lens group G1 corresponds to the object-side lens group GF, and the combined group of the second lens group G2 and the third lens group G3 corresponds to the image plane-side lens group GR.

[0190] The first lens group G1 consists of, in order from the object side, a positive meniscus lens L1 with its convex surface facing the object, a positive meniscus lens L2 with its convex surface facing the object, a positive meniscus lens L3 with its convex surface facing the object, a cemented lens consisting of a positive meniscus lens L4 with its convex surface facing the object and a negative meniscus lens L5 with its convex surface facing the object, and a positive meniscus lens L6 with its convex surface facing the object. The positive meniscus lens L2 corresponds to lens LA in this invention.

[0191] The second lens group G2 consists solely of a negative meniscus lens L7 with its convex surface facing the object. When focusing from an object at infinity to a close distance, the entire second lens group G2 moves towards the image plane.

[0192] The third lens group G3 consists of a cemented lens comprising a negative meniscus lens L8 with a convex surface facing the object side and a biconvex lens L9, a cemented lens comprising a biconcave lens L10 and a biconvex lens L11, a biconvex lens L12, a biconcave lens L13, and a negative meniscus lens L14 with a convex surface facing the image plane side, with the lens surfaces on both sides of the negative meniscus lens L14 with a convex surface facing the image plane side having a predetermined aspherical shape. The biconcave lens L13 corresponds to lens LA in this invention.

[0193] The specifications of the optical system according to Example 7 are shown below. Numerical Example 7 Unit: mm [Surface data] Face number rd nd vd θgF Object surface ∞ (d0) 1 72.6808 5.0242 1.94595 17.98 0.654432 2 104.0955 0.7000 3 72.1022 7.9180 1.41390 100.82 0.533605 4 217.7112 0.1500 5 54.3986 7.8515 1.59282 68.62 0.544009 6 118.8800 0.7000 7 42.8489 9.9642 1.55032 75.50 0.539881 8 218.4736 1.4000 1.85478 24.80 0.612166 9 28.4179 3.9004 10 39.3462 6.0649 1.59282 68.62 0.544009 11 127.4290 5.4355 12 (aperture) ∞ (d12) 13 657.7179 1.0000 1.51742 52.15 0.558829 14 28.1131 (d14) 15 287.8934 0.9000 1.85451 25.15 0.610160 16 25.1931 5.5789 1.59282 68.62 0.544009 17 -106.2671 2.5244 18 -44.0902 0.9500 1.55032 75.50 0.539881 19 92.5544 3.7150 1.68430 26.81 0.623031 20 -89.6313 0.1500 21 96.6146 5.8235 1.78880 28.43 0.600773 22 -42.0630 0.1500 23 -75.0235 1.0000 1.41390 100.82 0.533605 24 89.0720 3.6009 25* -90.9091 1.7000 1.51633 64.06 0.533322 26* -200.0000 (BF) Image plane ∞ [Aspherical data] Pages 25 and 26 K 0.00000 0.00000 A4 2.23113E-06 3.95648E-06 A6 -2.52151E-08 -2.40968E-08 A8 9.33417E-11 6.86747E-11 A10 -1.19404E-13 -5.63942E-14 A12 3.13559E-17 -3.57179E-17 H14 0.00000E+00 0.00000E+00 [Various Data] INF 800mm Focal length 131.00 111.39 F-number 1.85 2.10 Full angle of view 2ω 18.04 15.44 Image height Y 21.63 21.63 Lens length 129.50 129.50 [Variable interval data] INF 800mm d0 ∞ 670.5000 d12 3.9792 17.1120 d14 18.8972 5.7644 BF 30.4221 30.4221 [Lens group data] Group starting plane focal length G1 1 78.79 G2 13 -56.79 G3 15 101.15

[0194] The corresponding values ​​for each example are shown below. [Conditional expression corresponding value] Conditional expression Example 1 Example 2 Example 3 Example 4 (1) VD_A > 96.00 100.82 100.82 100.82 97.75 (2) ΔθgF_A > 0.057 0.067 0.067 0.067 0.062 Conditional expression Example 5 Example 6 Example 7 (1) VD_A > 96.00 100.82 97.75~100.82 100.82 (2) ΔθgF_A > 0.057 0.067 0.062~0.067 0.067 (3) DAF / f > 0.270 0.346 0.372~0.463 0.271 (4) DAR / f > 0.120 0.124 0.137 0.333 (5) 0.40 > DFR / LT > 0.10 0.3456 0.1922 0.1459 (6) 0.70 > HS / HR1 > 0.20 0.2831 0.3158 0.5084 [Explanation of symbols]

[0195] S: Aperture diaphragm I: image plane G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: Lens group #6 G7: 7th lens group G8: 8th lens group GF: Object-side lens group GR: Image plane lens group CC line (wavelength λ=656.3nm) dd line (wavelength λ=587.6nm) gg line (wavelength λ=435.8nm) Y image height ΔS sagittal image plane ΔM Meridional Image Surface

Claims

1. An optical system comprising an object-side lens group GF and an image-plane lens group GR arranged in order from the object side, having an aperture diaphragm, and a lens LA that satisfies the following condition (1). (1) VD_A > 96.00 however, VD_A: Abbe number based on the d line of the lens LA.

2. In the optical system described in claim 1, An optical system characterized in that the lens LA satisfies the following condition (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: The average value of the deviation ΔθgF of the partial dispersion ratio of the lens LA with respect to the g line. Here, the deviation ΔθgF of the partial variance ratio relative to the g line is given by θgF, where θgF is the partial variance ratio relative to the g line and VD is the Abbe number on the d line. ΔθgF=θgF-(0.648285-0.00180123×VD) This is calculated for each lens.

3. In the optical system described in claim 1 or 2, When the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during the magnification process. The lens LA is positioned in the object-side lens group GF and has a positive refractive power. An optical system characterized by satisfying the following condition (3). (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the lens is in focus at infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

4. In the optical system described in claim 1 or 2, When the optical system is magnified, the distance between at least the object-side lens group GF and the image plane-side lens group GR changes during the magnification process. The lens LA is arranged in the image plane side lens group GR and has a negative refractive power. An optical system characterized by satisfying the following condition (4). (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA positioned in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA positioned in the image-plane lens group GR, when the lens is focused at infinity at its maximum telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

5. In the optical system described in claim 1, When the optical system is magnified, at the maximum telephoto setting when it is focused at infinity, or when the optical system is not magnified, at the setting when it is focused at infinity, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses of the optical system. The lens LA is positioned in the object-side lens group GF and has a positive refractive power. An optical system characterized by satisfying the following condition (3). (3) DAF / f > 0.270 however, If the optical system does not change magnification, DAF: The distance along the optical axis between the image plane side surface of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the lens is in focus at infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAF: The distance along the optical axis between the image plane side of lens LA, which is located in the object-side lens group GF, and the aperture diaphragm when the focus is on infinity at the most telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

6. In the optical system described in claim 1, When the optical system is magnified, at the maximum telephoto setting when it is focused at infinity, or when the optical system is not magnified, at the setting when it is focused at infinity, the distance between the object-side lens group GF and the image-plane-side lens group GR is the maximum distance between adjacent lenses of the optical system. The lens LA is arranged in the image plane side lens group GR and has a negative refractive power. An optical system characterized by satisfying the following condition (4). (4) DAR / f > 0.120 however, If the optical system does not change magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA positioned in the image-plane lens group GR when the focus is set to infinity. f: The focal length of the optical system when in focus at infinity. When the optical system changes magnification, DAR: The distance along the optical axis between the aperture diaphragm and the object-side surface of the lens LA positioned in the image-plane lens group GR, when the lens is focused at infinity at its maximum telephoto setting. f: The focal length of the optical system when it is in focus at infinity at its most telephoto setting.

7. In the optical system described in claim 5 or 6, An optical system characterized by satisfying the following condition (5). (5) 0.40 > DFR / LT > 0.10 however, If the optical system does not change magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image plane-side lens group GR when in focus at infinity. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the system is focused at infinity. When the optical system changes magnification, DFR: The air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR when the focus is on infinity at the most telephoto setting. LT: The distance along the optical axis between the object-side surface of the optical system and the image plane when the optical system is in focus at infinity at its most telephoto setting.

Images