Optical System and Optical Device

Abstract

The present invention provides an optical system and an optical device. The optical system (LS) includes lenses (L22, L33) that satisfy the following conditional expressions: νdLZ < 35.0, 0.702 < θgFLZ + (0.00316 × νdLZ) where νdLZ: the Abbe number of the lens based on the d line, θgFLZ: the relative partial dispersion of the lens, when the refractive index of the lens with respect to the g line is ngLZ, the refractive index of the lens with respect to the F line is nFLZ, and the refractive index of the lens with respect to the C line is nCLZ, it is defined by the following formula, θgFLZ = (ngLZ - nFLZ) / (nFLZ - nCLZ).

Description

[0001] This application is a divisional application of a patent application for an invention titled "Optical System and Optical Device" with an international filing date of December 15, 2017, an international application number of PCT / JP2017 / 045188, and a national application number of 201780097705.1. Technical Field

[0002] The present invention relates to an optical system, an optical device, and a method for manufacturing an optical system. Background Art

[0003] In recent years, imaging elements used in imaging devices such as digital cameras and video cameras have been advancing toward higher pixel counts. The photographic lens provided in an imaging device using such an imaging element is preferably a lens that, in addition to basic aberrations (aberration of a single wavelength) such as spherical aberration and coma, also corrects chromatic aberration well so that there is no blurring in the color of the image under white light source and has high resolution. In particular, it is preferable that, in the correction of chromatic aberration, in addition to primary achromatism, secondary spectrum is also corrected well. As a means for correcting chromatic aberration, for example, a method of using a resin material having anomalous dispersion characteristics is known (for example, refer to Patent Document 1). As described above, with the recent increase in pixel count of imaging elements, it is desired to realize a photographic lens that corrects each aberration well.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-194609 Summary of the Invention

[0007] The optical system of the first aspect has a lens that satisfies the following conditional expression:

[0008] νdLZ < 35.0

[0009] 0.702 < θgFLZ + (0.00316 × νdLZ)

[0010] where νdLZ: the Abbe number of the lens based on the d line

[0011] θgFLZ: the relative partial dispersion of the lens, which is defined by the following formula when the refractive index of the lens with respect to the g line is ngLZ, the refractive index of the lens with respect to the F line is nFLZ, and the refractive index of the lens with respect to the C line is nCLZ:

[0012] θgFLZ = (ngLZ - nFLZ) / (nFLZ - nCLZ).

[0013] The optical device of the second mode is configured to include the above optical system.

[0014] A method for manufacturing an optical system of a third mode, in which each lens is arranged in a lens barrel in such a manner that the lens satisfies the following conditional expression:

[0015] νdLZ < 35.0

[0016] 0.702 < θgFLZ + (0.00316 × νdLZ)

[0017] where νdLZ: the Abbe number of the lens based on the d line

[0018] θgFLZ: the relative partial dispersion of the lens, which is defined by the following formula when the refractive index of the lens with respect to the g line is ngLZ, the refractive index of the lens with respect to the F line is nFLZ, and the refractive index of the lens with respect to the C line is nCLZ

[0019] θgFLZ = (ngLZ - nFLZ) / (nFLZ - nCLZ). Description of the Drawings

[0020] Figure 1 It is a lens structure diagram in the infinity focus state of the optical system of the first embodiment.

[0021] Figure 2 It is an aberration diagram in the infinity focus state of the optical system of the first embodiment.

[0022] Figure 3 It is a lens structure diagram in the infinity focus state of the optical system of the second embodiment.

[0023] Figure 4 (A), Figure 4 (B), and Figure 4 (C) are aberration diagrams in the infinity focus state in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system of the second embodiment, respectively.

[0024] Figure 5 It is a lens structure diagram in the infinity focus state of the optical system of the third embodiment.

[0025] Figure 6 It is an aberration diagram in the infinity focus state of the optical system of the third embodiment.

[0026] Figure 7 It is a lens structure diagram in the infinity focus state of the optical system of the fourth embodiment.

[0027] Figure 8 (A), Figure 8 (B), and Figure 8(C) are aberration diagrams at infinity focus in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system of the fourth embodiment, respectively.

[0028] Figure 9 is a lens structure diagram of the optical system of the fifth embodiment in the infinity focus state.

[0029] Figure 10 (A), Figure 10 (B), and Figure 10 (C) are aberration diagrams at infinity focus in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system of the fifth embodiment, respectively.

[0030] Figure 11 is a lens structure diagram of the optical system of the sixth embodiment in the infinity focus state.

[0031] Figure 12 are aberration diagrams of the optical system of the sixth embodiment in the infinity focus state.

[0032] Figure 13 is a lens structure diagram of the optical system of the seventh embodiment in the infinity focus state.

[0033] Figure 14 are aberration diagrams of the optical system of the seventh embodiment in the infinity focus state.

[0034] Figure 15 is a diagram showing the structure of a camera equipped with the optical system of this embodiment.

[0035] Figure 16 is a flowchart showing the manufacturing method of the optical system of this embodiment. Detailed Embodiment

[0036] Hereinafter, the optical system and the optical device of this embodiment will be described with reference to the drawings. First, according to Figure 15 a camera (optical device) equipped with the optical system of this embodiment will be described. As Figure 15 shown, this camera 1 is a digital camera equipped with the optical system of this embodiment as a photographic lens 2. In the camera 1, light from an object (subject) (not shown) is condensed by the photographic lens 2 and reaches the imaging element 3. Thus, the light from the subject is imaged by this imaging element 3 and recorded as a subject image in a memory (not shown). Thereby, a photographer can photograph a subject using the camera 1. In addition, this camera can be a mirrorless camera or a single-lens reflex type camera with a quick-recovery mirror.

[0037] As Figure 1As shown, the optical system LS(1) which is an example of the optical system (photographic lens) LS of the present embodiment has lenses (L22, L33) that satisfy the following conditional expressions (1) to (2). In the present embodiment, in order to distinguish from other lenses, the lenses that satisfy the conditional expressions (1) to (2) are sometimes referred to as specific lenses.

[0038] νdLZ < 35.0 …(1)

[0039] 0.702 < θgFLZ + (0.00316 × νdLZ) …(2)

[0040] Wherein, νdLZ: Abbe number of the specific lens based on the d line

[0041] θgFLZ: relative partial dispersion of the specific lens. When the refractive index of the specific lens for the g line is ngLZ, the refractive index of the specific lens for the F line is nFLZ, and the refractive index of the specific lens for the C line is nCLZ, it is defined by the following formula

[0042] θgFLZ = (ngLZ - nFLZ) / (nFLZ - nCLZ)

[0043] In addition, the Abbe number νdLZ of the specific lens based on the d line is defined by the following formula

[0044] νdLZ = (ndLZ - 1) / (nFLZ - nCLZ)

[0045] According to the present embodiment, an optical system that well corrects the secondary spectrum in addition to primary achromatism in the correction of chromatic aberration and an optical device including the optical system can be obtained. The optical system LS of the present embodiment can be Figure 3 the optical system LS(2) shown, or can be Figure 5 the optical system LS(3) shown, or can be Figure 7 the optical system LS(4) shown. In addition, the optical system LS of the present embodiment can be Figure 9 the optical system LS(5) shown, or can be Figure 11 the optical system LS(6) shown, or can be Figure 13 the optical system LS(7) shown.

[0046] The conditional expression (1) specifies an appropriate range of the Abbe number of the specific lens based on the d line. By satisfying the conditional expression (1), it is possible to well correct basic aberrations such as spherical aberration and coma and primary chromatic aberration (achromatism).

[0047] When the corresponding value of conditional expression (1) exceeds the upper limit value, for example, it is difficult to correct axial chromatic aberration in a partial group closer to the object side or the image side than the aperture stop S, so it is not preferable. By setting the upper limit value of conditional expression (1) to 32.5, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of conditional expression (1) is 32.0, 31.5, 31.0, 30.5, 30.0, and further 29.5.

[0048] Conditional expression (2) appropriately defines the anomalous dispersion characteristics of a specific lens. By satisfying conditional expression (2), in the correction of chromatic aberration, in addition to primary achromatism, secondary spectrum can also be corrected well.

[0049] When the corresponding value of conditional expression (2) is lower than the lower limit value, the anomalous dispersion characteristics of the specific lens become small, so it is difficult to correct chromatic aberration. By setting the lower limit value of conditional expression (2) to 0.704, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of conditional expression (2) is 0.708, 0.710, 0.712, and further 0.715.

[0050] In the optical system of the present embodiment, the specific lens preferably satisfies the following conditional expression (3).

[0051] ndLZ+(0.01425×νdLZ)<2.12…(3)

[0052] where, ndLZ: refractive index of the specific lens for the d line

[0053] Conditional expression (3) defines an appropriate relationship between the refractive index of the specific lens for the d line and the Abbe number based on the d line. By satisfying conditional expression (3), spherical aberration, coma, and other basic aberrations and primary chromatic aberration (achromatism) can be corrected well.

[0054] When the corresponding value of conditional expression (3) exceeds the upper limit value, for example, the Petzval sum becomes smaller, so it is difficult to correct field curvature, so it is not preferable. By setting the upper limit value of conditional expression (3) to 2.11, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of conditional expression (3) is 2.10, 2.09, 2.08, 2.07, and further 2.06.

[0055] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (1-1).

[0056] 18.0<νdLZ<35.0…(1-1)

[0057] The conditional expression (1-1) is the same as the conditional expression (1). By satisfying the conditional expression (1-1), it is possible to perform good correction of basic aberrations such as spherical aberration and coma, and correction of primary chromatic aberration (achromatism). By setting the upper limit value of the conditional expression (1-1) to 32.5, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (1-1) is 32.0, 31.5, 31.0, 30.5, 30.0, and further 29.5. On the other hand, by setting the lower limit value of the conditional expression (1-1) to 20.0, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (1-1) is 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.0, 27.5, and further 27.7.

[0058] In the optical system of the present embodiment, the specific lens preferably satisfies the following conditional expression (4).

[0059] 1.83 < ndLZ + (0.00787 × νdLZ)…(4)

[0060] The conditional expression (4) stipulates the appropriate relationship between the refractive index of the specific lens for the d-line and the Abbe number based on the d-line. By satisfying the conditional expression (4), it is possible to perform good correction of basic aberrations such as spherical aberration and coma, and correction of primary chromatic aberration (achromatism).

[0061] When the corresponding value of the conditional expression (4) is lower than the lower limit value, for example, the refractive index of the specific lens becomes smaller, making it difficult to correct basic aberrations, especially spherical aberration. Therefore, it is not preferred. By setting the lower limit value of the conditional expression (4) to 1.84, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (4) is 1.85, and further 1.86.

[0062] In the optical system of the present embodiment, the specific lens preferably satisfies the following conditional expression (5).

[0063] 1.55 < ndLZ…(5)

[0064] The conditional expression (5) stipulates the appropriate range of the refractive index of the specific lens for the d-line. By satisfying the conditional expression (5), it is possible to perform good correction of various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration).

[0065] When the corresponding value of conditional expression (5) is lower than the lower limit value, it is difficult to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration), which is not preferable. By setting the lower limit value of conditional expression (5) to 1.58, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of conditional expression (5) is 1.60, 1.62, 1.65, 1.68, 1.70, and further 1.72.

[0066] In the optical system of the present embodiment, the specific lens preferably satisfies the following conditional expression (6).

[0067] DLZ>0.80…(6)

[0068] where, DLZ: thickness on the optical axis of the specific lens [mm]

[0069] Conditional expression (6) defines an appropriate range of the thickness on the optical axis of the specific lens. By satisfying conditional expression (6), various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well.

[0070] When the corresponding value of conditional expression (6) is lower than the lower limit value, it is difficult to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration), which is not preferable. By setting the lower limit value of conditional expression (6) to 0.90, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of conditional expression (6) is 1.00, 1.10, 1.20, and further 1.30.

[0071] In the optical system of the present embodiment, the specific lens preferably satisfies the following conditional expressions (5-1) and (7).

[0072] ndLZ<1.63…(5-1)

[0073] ndLZ-(0.040×νdLZ-2.470)×νdLZ<39.809…(7)

[0074] Conditional expression (5-1) is the same as conditional expression (5). By satisfying conditional expression (5-1), various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well. By setting the upper limit value of conditional expression (5-1) to 1.62, the effects of the present embodiment can be obtained more reliably.

[0075] Conditional expression (7) defines an appropriate relationship between the refractive index of the specific lens for the d line and the Abbe number based on the d line. By satisfying conditional expression (7), basic aberrations such as spherical aberration and coma and primary chromatic aberration correction (achromatism) can be performed well.

[0076] When the corresponding value of conditional expression (7) exceeds the upper limit value, for example, the Petzval sum becomes smaller, making it difficult to correct the image plane curvature. Therefore, this is not preferable. By setting the upper limit value of conditional expression (7) to 39.800, the effects of the present embodiment can be obtained more reliably.

[0077] In the optical system of the present embodiment, a specific lens preferably satisfies the following conditional expression (8).

[0078] ndLZ - (0.020 × νdLZ - 1.080) × νdLZ < 16.260…(8)

[0079] Conditional expression (8) stipulates an appropriate relationship between the refractive index of a specific lens for the d-line and the Abbe number based on the d-line. By satisfying conditional expression (8), it is possible to satisfactorily correct basic aberrations such as spherical aberration and coma, and primary chromatic aberration (achromatism).

[0080] When the corresponding value of conditional expression (8) exceeds the upper limit value, for example, the Petzval sum becomes smaller, making it difficult to correct the image plane curvature. Therefore, this is not preferable. By setting the upper limit value of conditional expression (8) to 16.240, the effects of the present embodiment can be obtained more reliably.

[0081] In the optical system of the present embodiment, a specific lens may also satisfy the following conditional expression (1 - 2).

[0082] 18.0 < νdLZ < 27.0…(1 - 2)

[0083] Conditional expression (1 - 2) is the same as conditional expression (1). By satisfying conditional expression (1 - 2), it is possible to satisfactorily correct basic aberrations such as spherical aberration and coma, and primary chromatic aberration (achromatism). By setting the upper limit value of conditional expression (1 - 2) to 26.6, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of conditional expression (1 - 2) is 26.3, 26.0, 25.7, and further 25.4. On the other hand, by setting the lower limit value of conditional expression (1 - 2) to 21.0, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of conditional expression (1 - 2) is 21.5, 22.0, 22.5, and further 23.0.

[0084] In the optical system of the present embodiment, a specific lens may also satisfy the following conditional expression (5 - 2).

[0085] 1.700 < ndLZ < 1.850…(5 - 2)

[0086] The conditional expression (5-2) is the same as the conditional expression (5). By satisfying the conditional expression (5-2), various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well. By setting the upper limit value of the conditional expression (5-2) to 1.830, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (5-2) is 1.810, 1.790, 1.770, and further 1.764. On the other hand, by setting the lower limit value of the conditional expression (5-2) to 1.709, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (5-2) is 1.718, 1.727, 1.736, and further 1.745.

[0087] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (2-1).

[0088] 0.702 < θgFLZ + (0.00316 × νdLZ) < 0.900…(2-1)

[0089] The conditional expression (2-1) is the same as the conditional expression (2). By satisfying the conditional expression (2-1), in the correction of chromatic aberration, in addition to primary achromatism, secondary spectrum can also be corrected well. By setting the upper limit value of the conditional expression (2-1) to 0.850, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (2-1) is 0.800, and further 0.720. On the other hand, by setting the lower limit value of the conditional expression (2-1) to 0.704, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (2-1) is 0.706.

[0090] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (5-3).

[0091] 1.550 < ndLZ < 1.700…(5-3)

[0092] The conditional expression (5-3) is the same as the conditional expression (5). By satisfying the conditional expression (5-3), it is possible to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) well. By setting the upper limit value of the conditional expression (5-3) to 1.699, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (5-3) is 1.698, 1.697, 1.696, and further 1.695. On the other hand, by setting the lower limit value of the conditional expression (5-3) to 1.560, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (5-3) is 1.570, 1.580, 1.590, and further 1.600.

[0093] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (1-3).

[0094] 27.0 < νdLZ < 35.0…(1-3)

[0095] The conditional expression (1-3) is the same as the conditional expression (1). By satisfying the conditional expression (1-3), it is possible to correct basic aberrations such as spherical aberration and coma and primary chromatic aberration (achromatism) well. By setting the upper limit value of the conditional expression (1-3) to 34.5, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (1-3) is 34.0, 33.5, and further 32.9. On the other hand, by setting the lower limit value of the conditional expression (1-3) to 28.0, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (1-3) is 29.0, 30.0, and further 31.0.

[0096] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (5-4).

[0097] 1.550 < ndLZ < 1.700…(5-4)

[0098] The conditional expression (5-4) is the same as the conditional expression (5). By satisfying the conditional expression (5-4), it is possible to correct various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) well. By setting the upper limit value of the conditional expression (5-4) to 1.675, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (5-4) is 1.660, 1.645, 1.630, and further 1.615. On the other hand, by setting the lower limit value of the conditional expression (5-4) to 1.560, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (5-4) is 1.570, 1.580, 1.590, and further 1.600.

[0099] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (1-4).

[0100] 25.0 < νdLZ < 31.0…(1-4)

[0101] The conditional expression (1-4) is the same as the conditional expression (1). By satisfying the conditional expression (1-4), it is possible to correct basic aberrations such as spherical aberration and coma and primary chromatic aberration (achromatism) well. By setting the upper limit value of the conditional expression (1-4) to 30.9, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (1-4) is 30.8. On the other hand, by setting the lower limit value of the conditional expression (1-4) to 25.6, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (1-4) is 26.0, 26.4, and further 26.8.

[0102] In the optical system of the present embodiment, the specific lens may also satisfy the following conditional expression (5-5).

[0103] 1.550 < ndLZ < 1.800…(5-5)

[0104] The conditional expression (5-5) is the same as the conditional expression (5). By satisfying the conditional expression (5-5), various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well. By setting the upper limit value of the conditional expression (5-5) to 1.770, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the upper limit value of the conditional expression (5-5) is 1.745, 1.720, and further 1.695. On the other hand, by setting the lower limit value of the conditional expression (5-5) to 1.565, the effects of the present embodiment can be obtained more reliably. In order to obtain the effects of the present embodiment more reliably, preferably, the lower limit value of the conditional expression (5-5) is 1.590, 1.605, and further 1.622.

[0105] In the optical system of the present embodiment, preferably, an object-side lens disposed closest to the object side is provided, and a specific lens is disposed on the image side with respect to the object-side lens. Thereby, various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well.

[0106] In the optical system of the present embodiment, preferably, an image-side lens disposed closest to the image side is provided, and a specific lens is disposed on the object side with respect to the image-side lens. Thereby, various aberrations such as coma and chromatic aberration (axial chromatic aberration and lateral chromatic aberration) can be corrected well.

[0107] In the optical system of the present embodiment, the specific lens is preferably a glass lens. Thereby, a lens that is resistant to environmental changes such as aging and temperature changes can be obtained as compared with the case where the material is resin.

[0108] Next, with reference to Figure 16 , an overview of the manufacturing method of the above optical system LS will be given. First, at least one lens is arranged (step ST1). At this time, each lens is arranged in the lens barrel such that at least one of these lenses (specific lens) satisfies the above conditional expressions (1) to (2) etc. (step ST2). According to this manufacturing method, an optical system that corrects secondary spectrum well in addition to primary achromatism in the correction of chromatic aberration can be manufactured.

[0109] Examples

[0110] Hereinafter, the optical system LS of the example of the present embodiment will be described with reference to the drawings. Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13It is a cross-sectional view showing the structure and focal power distribution of the optical systems LS {LS(1) to LS(7)} of the first to seventh embodiments. In the cross-sectional views of the optical system LS(1) of the first embodiment, the optical system LS(3) of the third embodiment, and the optical systems LS(6) to LS(7) of the sixth to seventh embodiments, the moving direction of the focusing lens group when focusing from infinity to a nearby object is indicated by an arrow together with words such as "focus". In the cross-sectional views of the optical system LS(2) of the second embodiment and the optical systems LS(4) to LS(5) of the fourth to fifth embodiments, the moving direction of each lens group along the optical axis when zooming from the wide-angle end state (W) to the telephoto end state (T) is indicated by an arrow.

[0111] In these Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13 , each lens group is represented by a combination of the symbol G and a number, and each lens is represented by a combination of the symbol L and a number. In this case, in order to prevent the types and quantities of symbols and numbers from becoming numerous and complicated, the combinations of symbols and numbers are independently used for each embodiment to represent lens groups and the like. Therefore, even if the same combination of symbols and numbers is used between embodiments, it does not mean the same structure.

[0112] Tables 1 to 7 are shown below. Table 1 is a table showing the parameter data in the first embodiment, Table 2 is a table showing the parameter data in the second embodiment, Table 3 is a table showing the parameter data in the third embodiment, Table 4 is a table showing the parameter data in the fourth embodiment, Table 5 is a table showing the parameter data in the fifth embodiment, Table 6 is a table showing the parameter data in the sixth embodiment, and Table 7 is a table showing the parameter data in the seventh embodiment. In each embodiment, as the calculation object of aberration characteristics, the d-line (wavelength λ = 587.6 nm), g-line (wavelength λ = 435.8 nm), C-line (wavelength λ = 656.3 nm), and F-line (wavelength λ = 486.1 nm) are selected.

[0113] In the table of [overall parameters], f represents the focal length of the entire lens system, FNO represents the F-number, 2ω represents the field angle (unit: ° (degree), ω is the semi-field angle), and Y represents the image height. TL represents the distance obtained by adding BF to the distance from the frontmost lens to the final lens on the optical axis when focusing at infinity, and BF represents the distance from the final lens to the image plane I on the optical axis when focusing at infinity (back focal length). In addition, when the optical system is a zoom optical system, these values are shown for each zoom state of the wide-angle end (W), intermediate focal length (M), and telephoto end (T).

[0114] In the table of [lens parameters], the surface number indicates the order of the optical surfaces starting from the object side along the direction of light travel. R represents the radius of curvature of each optical surface (a positive value for a surface with the center of curvature on the image side). D represents the distance on the optical axis from each optical surface to the next optical surface (or the image surface), i.e., the surface interval. nd represents the refractive index of the material of the optical component for the d-line. νd represents the Abbe number of the material of the optical component based on the d-line. θgF represents the relative partial dispersion of the material of the optical component. "∞" for the radius of curvature indicates a plane or an aperture, and (aperture S) indicates the aperture stop S. The notation of the refractive index of air nd = 1.00000 is omitted. When the optical surface is an aspherical surface, an *a mark is attached to the surface number. When the optical surface is a diffractive optical surface, a *b mark is attached to the surface number, and the paraxial radius of curvature is indicated in the column of the radius of curvature R.

[0115] Let the refractive index of the material of the optical component for the g-line (wavelength λ = 435.8 nm) be ng, let the refractive index of the material of the optical component for the F-line (wavelength λ = 486.1 nm) be nF, and let the refractive index of the material of the optical component for the C-line (wavelength λ = 656.3 nm) be nC. At this time, the relative partial dispersion θgF of the material of the optical component is defined by the following formula (A).

[0116] θgF = (ng - nF) / (nF - nC) …(A)

[0117] In the table of [aspherical data], for the aspherical surface shown in [lens parameters], its shape is represented by the following formula (B). X(y) represents the distance (recess amount) along the optical axis direction from the tangent plane at the vertex of the aspherical surface to the position on the aspherical surface at height y. R represents the radius of curvature of the reference sphere (paraxial radius of curvature). κ represents the conic constant. Ai represents the i-th aspherical coefficient. "E-n" represents "×10 -n ". For example, 1.234E-05 = 1.234×10 -5 . In addition, the second-order aspherical coefficient A2 is 0, and its notation is omitted.

[0118] X(y) = (y 2 / R) / {1 + (1 - κ×y 2 / R 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 …(B)

[0119] When the optical system has a diffractive optical element, the phase shape ψ of the diffractive optical surface shown in [diffractive optical surface data] is represented by the following formula (C).

[0120] ψ(h, m) = {2π / (m × λ0)} × (C2 × h 2 + C4 × h 4 + C6 × h 6 …) …(C)

[0121] wherein,

[0122] h: the height in the direction perpendicular to the optical axis,

[0123] m: the diffraction order of the diffracted light,

[0124] λ0: the designed wavelength,

[0125] Ci: the phase coefficient (i = 2, 4, …).

[0126] In addition, regarding the optical power of the diffractive surface at any wavelength λ and any diffraction order m, it can be expressed using the lowest-order phase coefficient C2 as shown in the following formula (D).

[0127]

[0128] In the table of [Diffractive Optical Surface Data], for the diffractive optical surface shown in [Lens Parameters], the designed wavelength λ0, diffraction order m, quadratic phase coefficient C2, and quartic phase coefficient C4 in formula (C) are shown. "E-n" represents "×10 -n " in the same way as the table of [Aspherical Surface Data].

[0129] When the optical system is not a zoom optical system, as [Variable Interval Data for Close-Up Photography], f represents the focal length of the entire lens system, and β represents the photographic magnification. In addition, in the table of [Variable Interval Data for Close-Up Photography], the surface intervals at the surface numbers where the surface intervals become "variable" in [Lens Parameters] corresponding to each focal length and photographic magnification are shown.

[0130] When the optical system is a zoom optical system, as [Variable Interval Data for Zoom Photography], the surface intervals at the surface numbers where the surface intervals become "variable" in [Lens Parameters] corresponding to each zoom state of the wide-angle end (W), intermediate focal length (M), and telephoto end (T) are shown. In addition, in the table of [Lens Group Data], the starting surface (the surface closest to the object side) and focal length of each lens group are shown.

[0131] In the table of [Condition Formula Corresponding Values], the values corresponding to each condition formula are shown.

[0132] Hereinafter, among all parameter values, for the described focal length f, radius of curvature R, surface interval D, other lengths, etc., "mm" is generally used unless otherwise specified. However, even if the optical system is scaled up or down, the same optical performance can be obtained, so it is not limited thereto.

[0133] The explanations of the tables up to this point are the same in all embodiments, and the repeated explanations are omitted hereinafter.

[0134] (First Embodiment)

[0135] Use Figures 1 - 2 and Table 1 to explain the first embodiment. Figure 1 FIG. is a diagram showing the lens structure in an infinitely focused state of the optical system of the first embodiment of the present embodiment. The optical system LS(1) of the first embodiment is composed of a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, and a third lens group G3 having a positive optical power, which are arranged in order from the object side. When focusing from an infinitely distant object to a close (finite distance) object, the second lens group G2 moves toward the image side along the optical axis. The aperture stop S is arranged near the object side of the third lens group G3 and is fixed relative to the image plane I during focusing, similarly to the first lens group G1 and the third lens group G3. The symbols (+) or (-) attached to the reference numerals of the respective lens groups represent the optical powers of the respective lens groups, which is the same in all the following embodiments.

[0136] The first lens group G1 is composed of a protective glass HG having an extremely weak optical power, a biconvex positive lens L11, a biconvex positive lens L12, a biconcave negative lens L13, and a cemented lens composed of a negative meniscus lens L14 with the convex surface facing the object side and a positive meniscus lens L15 with the convex surface facing the object side, which are arranged in order from the object side. In the present embodiment, the positive lens L11 of the first lens group G1 corresponds to the object-side lens.

[0137] The second lens group G2 is composed of a biconcave negative lens L21 and a cemented lens composed of a positive meniscus lens L22 with the concave surface facing the object side and a biconcave negative lens L23, which are arranged in order from the object side. In the present embodiment, the positive meniscus lens L22 of the second lens group G2 corresponds to a lens (specific lens) that satisfies the conditional expressions (1) to (2), etc.

[0138] The third lens group G3 includes a first partial group G31 with a positive optical power, a second partial group G32 with a negative optical power, and a third partial group G33 with a positive optical power, which are arranged in sequence from the object side. The first partial group G31 is composed of a cemented lens formed by a positive lens L31 with a biconvex shape and a negative meniscus lens L32 with a concave surface facing the object side, which are arranged in sequence from the object side. The second partial group G32 is composed of a cemented lens formed by a positive lens L33 with a biconvex shape and a negative lens L34 with a biconcave shape, which are arranged in sequence from the object side, and a negative lens L35 with a biconcave shape. The third partial group G33 is composed of a positive lens L36 with a biconvex shape and a cemented lens formed by a positive lens L37 with a biconvex shape and a negative lens L38 with a biconcave shape, which are arranged in sequence from the object side. In this embodiment, the negative lens L38 of the third lens group G3 corresponds to the image-side lens, and the positive lens L33 of the third lens group G3 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc. The second partial group G33 of the third lens group G3 constitutes an anti-shake lens group (partial group) that can move in a direction perpendicular to the optical axis, and corrects the displacement of the imaging position (image shake on the image plane I) caused by hand shake or the like. In addition, a fixed aperture (spot shielding blade) Sa is arranged between the second partial group G32 and the third partial group G33 in the third lens group G3.

[0139] An image plane I is arranged on the image side of the third lens group G3. An optical filter FL that can be inserted and replaced is arranged between the third lens group G3 and the image plane I. As the optical filter FL that can be inserted and replaced, for example, an NC filter (neutral color filter), a color filter, a polarization filter, an ND filter (neutral density filter), an IR filter (infrared cut-off filter), etc. are used.

[0140] In Table 1 below, the parameter values of the optical system of the first embodiment are shown.

[0141] (Table 1)

[0142] [Overall parameters]

[0143]

[0144] [Lens parameters]

[0145]

[0146]

[0147] [Variable interval data during close-up photography]

[0148]

[0149] [Conditional expression corresponding values]

[0150] <Positive meniscus lens L22>

[0151] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0152] νdLZ = 26.87

[0153] Conditional expressions (2), (2-1)

[0154] θgFLZ + (0.00316 × νdLZ) = 0.7179 Conditional expression (3)

[0155] ndLZ + (0.01425 × νdLZ) = 2.042

[0156] Conditional expression (4)

[0157] ndLZ + (0.00787 × νdLZ) = 1.871

[0158] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0159] ndLZ = 1.65940

[0160] Conditional expression (6)

[0161] DLZ = 4.500

[0162] Conditional expression (7)

[0163] ndLZ - (0.040 × νdLZ - 2.470) × νdLZ = 39.148 Conditional expression (8)

[0164] ndLZ - (0.020 × νdLZ - 1.080) × νdLZ = 16.239

[0165] <Positive lens L33>

[0166] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0167] νdLZ = 24.66

[0168] Conditional expressions (2), (2-1)

[0169] θgFLZ + (0.00316 × νdLZ) = 0.7049 Conditional expression (3)

[0170] ndLZ + (0.01425 × νdLZ) = 2.101

[0171] Conditional expression (4)

[0172] ndLZ+(0.00787×νdLZ) = 1.944

[0173] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0174] ndLZ = 1.74971

[0175] Conditional expression (6)

[0176] DLZ = 4.700

[0177] Conditional expression (7)

[0178] ndLZ-(0.040×νdLZ - 2.470)×νdLZ = 38.335

[0179] Conditional expression (8)

[0180] ndLZ-(0.020×νdLZ - 1.080)×νdLZ = 16.220

[0181] Figure 2 These are the aberration diagrams in the infinity focus state of the optical system of the first embodiment. In each aberration diagram, FNO represents the F-number, and Y represents the image height. Additionally, in the spherical aberration diagram, the F-number or the value of the numerical aperture corresponding to the maximum aperture is shown. In the astigmatism diagram and the distortion diagram, the maximum value of the image height is shown respectively, and in the coma diagram, the values of each image height are shown. d represents the d-line (wavelength λ = 587.6 nm), g represents the g-line (wavelength λ = 435.8 nm), C represents the C-line (wavelength λ = 656.3 nm), and F represents the F-line (wavelength λ = 486.1 nm). In the astigmatism diagram, the solid line represents the sagittal image plane, and the dashed line represents the meridional image plane. Additionally, in the aberration diagrams of the following embodiments, the same symbols as in this embodiment are used, and repeated explanations are omitted.

[0182] It can be seen from each aberration diagram that the optical system of the first embodiment corrects each aberration well and has excellent imaging performance.

[0183] (Second Embodiment)

[0184] Use Figures 3 - 4 and Table 2 to describe the second embodiment. Figure 3This is a diagram showing the lens structure in the infinity focus state of the optical system according to the second embodiment of the present embodiment. The optical system LS(2) of the second embodiment is composed of a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, a third lens group G3 having a positive optical power, a fourth lens group G4 having a positive optical power, a fifth lens group G5 having a negative optical power, and a sixth lens group G6 having a negative optical power, which are arranged in sequence from the object side. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to fifth lens groups G1 to G5 move in the directions indicated by the arrows of Figure 3 respectively. The aperture stop S is disposed within the second lens group G2.

[0185] The first lens group G1 is composed of a cemented lens formed by a negative meniscus lens L11 with its convex surface facing the object side and a biconvex positive lens L12 arranged in sequence from the object side, and a positive meniscus lens L13 with its convex surface facing the object side. In this embodiment, the negative meniscus lens L11 of the first lens group G1 corresponds to the object-side lens. A diffractive optical element DOE is disposed on the image-side lens surface of the positive meniscus lens L13. The diffractive optical element DOE is, for example, a close-packed multilayer diffractive optical element in which two diffractive element elements of different materials are in contact in the same diffraction grating groove, and a first-order diffraction grating (a diffraction grating having a rotationally symmetric shape with respect to the optical axis) having a predetermined grating height is formed by two ultraviolet curable resins.

[0186] The second lens group G2 is composed of a cemented lens formed by a biconcave negative lens L21 and a positive meniscus lens L22 with its convex surface facing the object side arranged in sequence from the object side, a positive meniscus lens L23 with its concave surface facing the object side, and a positive meniscus lens L24 with its convex surface facing the object side. The aperture stop S is disposed between the positive meniscus lens L23 and the positive meniscus lens L24 in the second lens group G2. In this embodiment, the positive meniscus lens L22 of the second lens group G2 corresponds to a lens that satisfies the conditional expressions (1) to (2), etc. The cemented lens formed by the negative lens L21 and the positive meniscus lens L22 and the positive meniscus lens L23 in the second lens group G2 constitute an anti-shake lens group (partial group) that can move in a direction perpendicular to the optical axis, and corrects the displacement of the imaging position (image shake on the image plane I) caused by hand shake or the like.

[0187] The third lens group G3 is composed of a negative meniscus lens L31 with its convex surface facing the object side and a biconvex positive lens L32 arranged in sequence from the object side.

[0188] The fourth lens group G4 is composed of a cemented lens formed by a biconvex positive lens L41 and a negative meniscus lens L42 with its concave surface facing the object side arranged in sequence from the object side.

[0189] The fifth lens group G5 is composed of a cemented lens formed by a positive lens L51 with a biconvex shape and a negative lens L52 with a biconcave shape arranged in order from the object side. In this embodiment, focusing is performed by moving the entire fifth lens group G5 along the optical axis.

[0190] The sixth lens group G6 is composed of a cemented lens formed by a negative meniscus lens L61 with its convex surface facing the object side and a positive lens L62 with a biconvex shape, a negative lens L63 with a biconcave shape, and a negative meniscus lens L64 with its concave surface facing the object side, arranged in order from the object side. An image plane I is disposed on the image side of the sixth lens group G6. In this embodiment, the negative meniscus lens L64 of the sixth lens group G6 corresponds to the image-side lens, and the negative meniscus lens L61 of the sixth lens group G6 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc.

[0191] In Table 2 below, the parameter values of the optical system of the second embodiment are shown.

[0192] (Table 2)

[0193] [Overall parameters]

[0194]

[0195] [Lens parameters]

[0196]

[0197]

[0198] [Diffractive optical surface data]

[0199] The fifth surface

[0200] λ0 = 587.6

[0201] m = 1

[0202] C2 = -2.57E-05

[0203] C4 = -2.04E-11

[0204] [Variable interval data during variable magnification photography]

[0205]

[0206] [Lens group data]

[0207]

[0208] [Conditional expression corresponding values]

[0209] [Positive meniscus lens L22]

[0210] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0211] νdLZ = 26.87

[0212] Conditional expressions (2), (2-1)

[0213] θgFLZ + (0.00316 × νdLZ) = 0.7172 Conditional expression (3)

[0214] ndLZ + (0.01425 × νdLZ) = 2.042

[0215] Conditional expression (4)

[0216] ndLZ + (0.00787 × νdLZ) = 1.871

[0217] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0218] ndLZ = 1.659398

[0219] Conditional expression (6)

[0220] DLZ = 3.5689

[0221] Conditional expression (7)

[0222] ndLZ - (0.040 × νdLZ - 2.470) × νdLZ = 39.148

[0223] Conditional expression (8)

[0224] ndLZ - (0.020 × νdLZ - 1.080) × νdLZ = 16.239

[0225] <Negative meniscus lens L61>

[0226] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0227] νdLZ = 26.87

[0228] Conditional expressions (2), (2-1)

[0229] θgFLZ + (0.00316 × νdLZ) = 0.7172

[0230] Conditional expression (3)

[0231] ndLZ + (0.01425 × νdLZ) = 2.042

[0232] Conditional expression (4)

[0233] ndLZ+(0.00787×νdLZ)=1.871

[0234] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0235] ndLZ=1.659398

[0236] Conditional expression (6)

[0237] DLZ=1.7000

[0238] Conditional expression (7)

[0239] ndLZ-(0.040×νdLZ-2.470)×νdLZ=39.148

[0240] Conditional expression (8)

[0241] ndLZ-(0.020×νdLZ-1.080)×νdLZ=16.239

[0242] Figure 4 (A), Figure 4 (B), and Figure 4 (C) are aberration diagrams at infinity focus in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system of the second embodiment, respectively. From each aberration diagram, it can be seen that the optical system of the second embodiment corrects each aberration well and has excellent imaging performance.

[0243] (Third Embodiment)

[0244] Use Figures 5 - 6 and Table 3 to describe the third embodiment. Figure 5 is a diagram showing the lens structure in the infinity focus state of the optical system of the third embodiment of the present embodiment. The optical system LS(3) of the third embodiment is composed of a first lens group G1 having a negative optical power and a second lens group G2 having a positive optical power arranged in sequence from the object side. When focusing from an infinite object to a near (finite distance) object, the second lens group G2 moves toward the object side along the optical axis. The aperture stop S is disposed within the second lens group G2.

[0245] The first lens group G1 is composed of a negative meniscus lens L11 with its convex surface facing the object side, a positive lens L12 with a biconvex shape, a negative lens L13 with a biconcave shape, and a cemented lens composed of a positive lens L14 with a biconvex shape and a negative lens L15 with a biconcave shape, which are arranged in sequence from the object side. In this embodiment, the negative meniscus lens L11 of the first lens group G1 corresponds to the object-side lens, and the negative lens L15 of the first lens group G1 corresponds to the lens that satisfies the conditional expressions (1) to (2) and the like. The lens surface on the image side of the negative lens L13 is an aspherical surface.

[0246] The second lens group G2 is composed of a positive lens L21 with a biconvex shape, a cemented lens composed of a positive meniscus lens L22 with its convex surface facing the object side and a negative meniscus lens L23 with its convex surface facing the object side, a cemented lens composed of a negative lens L24 with a biconcave shape and a positive lens L25 with a biconvex shape, a positive lens L26 with a single-sided planar shape with its convex surface facing the image side, and a positive meniscus lens L27 with its concave surface facing the object side, which are arranged in sequence from the object side. An image plane I is arranged on the image side of the second lens group G2. An aperture stop S is arranged between the positive lens L21 and the positive meniscus lens L22 in the second lens group G2. In this embodiment, the positive meniscus lens L27 of the second lens group G2 corresponds to the image-side lens, and the positive meniscus lens L22 of the second lens group G2 corresponds to the lens that satisfies the conditional expressions (1) to (2) and the like. The lens surface on the image side of the positive lens L26 is an aspherical surface.

[0247] In Table 3 below, the parameter values of the optical system of the third embodiment are shown.

[0248] (Table 3)

[0249] [Overall parameters]

[0250]

[0251]

[0252] [Lens parameters]

[0253]

[0254]

[0255] [Aspherical data]

[0256] The 7th surface

[0257] κ = 0.0000

[0258] A4 = -2.99E-06, A6 = -2.39E-08, A8 = 1.13E-10, A10 = -3.69E-13

[0259] The 22nd surface

[0260] κ = 0.0000

[0261] A4 = 2.03E - 05, A6 = 4.37E - 09, A8 = 1.85E - 10, A10 = -1.33E - 12

[0262] [Variable interval data for close - up photography]

[0263] Infinity focus state Close - up focus state

[0264] f = 28.7734 β = -0.2174

[0265] D10 9.5660 2.3031

[0266] [Corresponding values of conditional expressions]

[0267] <Negative lens L15>

[0268] Conditional expressions (1), (1 - 1), (1 - 2), (1 - 3), (1 - 4)

[0269] νdLZ = 24.66

[0270] Conditional expressions (2), (2 - 1)

[0271] θgFLZ+(0.00316×νdLZ)=0.7051

[0272] Conditional expression (3)

[0273] ndLZ+(0.01425×νdLZ)=2.101

[0274] Conditional expression (4)

[0275] ndLZ+(0.00787×νdLZ)=1.944

[0276] Conditional expressions (5), (5 - 1), (5 - 2), (5 - 3), (5 - 4), (5 - 5)

[0277] ndLZ = 1.749714

[0278] Conditional expression (6)

[0279] DLZ = 1.7000

[0280] Conditional expression (7)

[0281] ndLZ-(0.040×νdLZ - 2.470)×νdLZ = 38.335

[0282] Conditional expression (8)

[0283] ndLZ - (0.020×νdLZ - 1.080)×νdLZ = 16.220

[0284] <Positive meniscus lens L22>

[0285] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0286] νdLZ = 26.87

[0287] Conditional expressions (2), (2-1)

[0288] θgFLZ + (0.00316×νdLZ) = 0.7172

[0289] Conditional expression (3)

[0290] ndLZ + (0.01425×νdLZ) = 2.042

[0291] Conditional expression (4)

[0292] ndLZ + (0.00787×νdLZ) = 1.871

[0293] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0294] ndLZ = 1.659398

[0295] Conditional expression (6)

[0296] DLZ = 1.3000

[0297] Conditional expression (7)

[0298] ndLZ - (0.040×νdLZ - 2.470)×νdLZ = 39.148

[0299] Conditional expression (8)

[0300] ndLZ - (0.020×νdLZ - 1.080)×νdLZ = 16.239

[0301] Figure 6 These are aberration diagrams in the infinity focus state of the optical system of the third embodiment. From each aberration diagram, it can be seen that the optical system of the third embodiment corrects each aberration well and has excellent imaging performance.

[0302] (Fourth Embodiment)

[0303] Use Figures 7 - 8 and Table 4 to illustrate the fourth embodiment. Figure 7This is a diagram showing the lens structure in the infinity focus state of the optical system according to the fourth embodiment of the present embodiment. The optical system LS(4) of the fourth embodiment is composed of a first lens group G1 with a positive optical power, a second lens group G2 with a negative optical power, a third lens group G3 with a positive optical power, and a fourth lens group G4 with a positive optical power, which are arranged in sequence from the object side. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in the directions indicated by the arrows of Figure 7 . The aperture stop S is arranged within the fourth lens group G4.

[0304] The first lens group G1 is composed of a biconvex positive lens L11 arranged in sequence from the object side and a cemented lens composed of a negative meniscus lens L12 with the convex surface facing the object side and a positive meniscus lens L13 with the convex surface facing the object side. In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object-side lens, and the negative meniscus lens L12 of the first lens group G1 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc.

[0305] The second lens group G2 is composed of a cemented lens composed of a biconcave negative lens L21 and a positive meniscus lens L22 with the convex surface facing the object side arranged in sequence from the object side and a biconcave negative lens L23.

[0306] The third lens group G3 is composed of a biconvex positive lens L31. In this embodiment, when focusing from an infinite object to a close (finite distance) object, the entire third lens group G3 moves along the optical axis toward the object side.

[0307] The fourth lens group G4 is composed of a cemented lens composed of a biconvex positive lens L41 and a biconcave negative lens L42 arranged in sequence from the object side, a biconvex positive lens L43, a cemented lens composed of a positive meniscus lens L44 with the concave surface facing the object side and a biconcave negative lens L45, a biconvex positive lens L46, and a negative meniscus lens L47 with the concave surface facing the object side. An image plane I is arranged on the image side of the fourth lens group G4. The aperture stop S is arranged between the positive lens L43 and the positive meniscus lens L44 in the fourth lens group G4. In this embodiment, the negative meniscus lens L47 of the fourth lens group G4 corresponds to the image-side lens.

[0308] In Table 4 below, the parameter values of the optical system of the fourth embodiment are shown.

[0309] (Table 4)

[0310] [Overall parameters]

[0311]

[0312] [Lens Parameters]

[0313]

[0314]

[0315] [Variable Interval Data during Zoom Photography]

[0316]

[0317] [Lens Group Data]

[0318]

[0319] [Conditional Corresponding Values]

[0320] Conditional Expressions (1), (1-1), (1-2), (1-3), (1-4)

[0321] νdLZ = 31.26

[0322] Conditional Expressions (2), (2-1)

[0323] θgFLZ + (0.00316 × νdLZ) = 0.7168 Conditional Expression (3)

[0324] ndLZ + (0.01425 × νdLZ) = 2.057 Conditional Expression (4)

[0325] ndLZ + (0.00787 × νdLZ) = 1.858

[0326] Conditional Expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0327] ndLZ = 1.61155

[0328] Conditional Expression (6)

[0329] DLZ = 1.7

[0330] Conditional Expression (7)

[0331] ndLZ - (0.040 × νdLZ - 2.470) × νdLZ = 39.736

[0332] Conditional Expression (8)

[0333] ndLZ - (0.020 × νdLZ - 1.080) × νdLZ = 15.829

[0334] Figure 8 (A), Figure 8 (B) and Figure 8(C) are aberration diagrams at infinity focus in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system of the fourth embodiment, respectively. From each aberration diagram, it can be seen that the optical system of the fourth embodiment corrects each aberration well and has excellent imaging performance.

[0335] (The Fifth Embodiment)

[0336] Use Figures 9 - 10 and Table 5 to describe the fifth embodiment. Figure 9 is a diagram showing the lens structure in the infinity focus state of the optical system of the fifth embodiment of the present embodiment. The optical system LS(5) of the fifth embodiment is composed of a first lens group G1 having a negative optical power, a second lens group G2 having a positive optical power, a third lens group G3 having a negative optical power, and a fourth lens group G4 having a positive optical power, which are arranged in order from the object side. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to fourth lens groups G1 to G4 move in the directions indicated by the arrows of Figure 9 respectively. The aperture stop S is arranged between the first lens group G1 and the second lens group G2, and moves along the optical axis together with the second lens group G2 during zooming.

[0337] The first lens group G1 is composed of a negative meniscus lens L11 with its convex surface facing the object side, a negative meniscus lens L12 with its convex surface facing the object side, a biconcave negative lens L13, and a biconvex positive lens L14, which are arranged in order from the object side. In this embodiment, the negative meniscus lens L11 of the first lens group G1 corresponds to the object-side lens. The lens surfaces on both sides of the negative meniscus lens L11 are aspherical surfaces. The image-side lens surface of the negative lens L13 is an aspherical surface.

[0338] The second lens group G2 is composed of a cemented lens composed of a negative meniscus lens L21 with its convex surface facing the object side and a positive meniscus lens L22 with its convex surface facing the object side, which are arranged in order from the object side, and a biconvex positive lens L23. In this embodiment, the negative meniscus lens L21 of the second lens group G2 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc.

[0339] The third lens group G3 is composed of a cemented lens composed of a biconvex positive lens L31 and a biconcave negative lens L32, which are arranged in order from the object side, a negative meniscus lens L33 with its concave surface facing the object side, and a biconvex positive lens L34. In this embodiment, when focusing from an infinite object to a near (finite distance) object, the negative meniscus lens L33 and the positive lens L34 of the third lens group G3 move toward the image side along the optical axis.

[0340] The fourth lens group G4 is composed of a cemented lens formed by a biconvex positive lens L41 and a biconcave negative lens L42 arranged in order from the object side, a biconvex positive lens L43, and a cemented lens formed by a biconvex positive lens L44 and a biconcave negative lens L45. An image plane I is disposed on the image side of the fourth lens group G4. In the present embodiment, the negative lens L45 of the fourth lens group G4 corresponds to the image-side lens. The lens surface on the image side of the negative lens L45 is an aspherical surface.

[0341] In Table 5 below, the parameter values of the optical system of the fifth embodiment are shown.

[0342] (Table 5)

[0343] [Overall parameters]

[0344]

[0345]

[0346] [Lens parameters]

[0347]

[0348]

[0349] [Aspherical data]

[0350] First surface

[0351] κ = 1.0000

[0352] A4 = 3.00E-06, A6 = 3.39E-09, A8 = 0.00E+00, A10 = 0.00E+00 Second surface

[0353] κ = 1.0000

[0354] A4 = -2.11E-05, A6 = 0.00E+00, A8 = 0.00E+00, A10 = 0.00E+00

[0355] Seventh surface

[0356] κ = 1.0000

[0357] A4 = 1.75E-05, A6 = -2.74E-08, A8 = 1.77E-11, A10 = 0.00E+00

[0358] Thirtieth surface

[0359] κ = 1.0000

[0360] A4 = 1.53E-05, A6 = 8.95E-09, A8 = 0.00E+00, A10 = 0.00E+00

[0361] [Variable interval data during variable magnification photography]

[0362]

[0363] [Lens group data]

[0364]

[0365]

[0366] [Conditional corresponding values]

[0367] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0368] νdLZ = 24.66

[0369] Conditional expressions (2), (2-1)

[0370] θgFLZ+(0.00316×νdLZ) = 0.7051

[0371] Conditional expression (3)

[0372] ndLZ+(0.01425×νdLZ) = 2.101

[0373] Conditional expression (4)

[0374] ndLZ+(0.00787×νdLZ) = 1.944

[0375] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0376] ndLZ = 1.74971

[0377] Conditional expression (6)

[0378] DLZ = 1.050

[0379] Conditional expression (7)

[0380] ndLZ-(0.040×νdLZ - 2.470)×νdLZ = 38.335

[0381] Conditional expression (8)

[0382] ndLZ-(0.020×νdLZ - 1.080)×νdLZ = 16.220

[0383] Figure 10 (A), Figure 10 (B), and Figure 10 (C) are aberration diagrams at infinity focus in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system of the fifth embodiment, respectively. From each aberration diagram, it can be seen that the optical system of the fifth embodiment corrects each aberration well and has excellent imaging performance.

[0384] (The sixth embodiment)

[0385] Use Figures 11 - 12 and Table 6 to describe the sixth embodiment. Figure 11 is a diagram showing the lens structure in the infinity focus state of the optical system of the sixth embodiment of the present embodiment. The optical system LS(6) of the sixth embodiment is composed of a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, and a third lens group G3 having a positive optical power, which are arranged in order from the object side. When focusing from an infinite object to a close (finite distance) object, the second lens group G2 moves toward the image side along the optical axis. The aperture stop S is arranged near the object side of the third lens group G3 and is fixed relative to the image plane I during focusing, like the first lens group G1 and the third lens group G3.

[0386] The first lens group G1 is composed of a protective glass HG having an extremely weak optical power, a biconvex positive lens L11, a biconvex positive lens L12, a biconcave negative lens L13, and a cemented lens composed of a negative meniscus lens L14 with the convex surface facing the object side and a positive meniscus lens L15 with the convex surface facing the object side, which are arranged in order from the object side. In this embodiment, the positive lens L11 of the first lens group G1 corresponds to the object-side lens.

[0387] The second lens group G2 is composed of a biconcave negative lens L21 and a cemented lens composed of a positive meniscus lens L22 with the concave surface facing the object side and a biconcave negative lens L23, which are arranged in order from the object side.

[0388] The third lens group G3 is composed of a positive lens L31 with a biconvex shape, a negative meniscus lens L32 with its concave surface facing the object side, which are arranged in sequence from the object side, a cemented lens composed of a positive lens L33 with a biconvex shape and a negative lens L34 with a biconcave shape, a negative lens L35 with a biconcave shape, a positive lens L36 with a biconvex shape, a cemented lens composed of a positive lens L37 with a biconvex shape and a negative lens L38 with a biconcave shape, a cemented lens composed of a positive meniscus lens L39 with its concave surface facing the object side and a negative meniscus lens L40 with its concave surface facing the object side, a cemented lens composed of a negative meniscus lens L41 with its convex surface facing the object side and a positive meniscus lens L42 with its convex surface facing the object side, a negative lens L43 with a biconcave shape, and a cemented lens composed of a positive lens L44 with a biconvex shape and a negative meniscus lens L45 with its concave surface facing the object side. In this embodiment, the negative meniscus lens L45 of the third lens group G3 corresponds to the image-side lens, and the positive meniscus lens L39 of the third lens group G3 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc.

[0389] An image plane I is disposed on the image side of the third lens group G3. Between the negative lens L38 and the positive meniscus lens L39 in the third lens group G3, an optical filter FL that can be inserted, pulled out, and replaced is disposed. As the optical filter FL that can be inserted, pulled out, and replaced, for example, an NC filter (neutral color filter), a color filter, a polarization filter, an ND filter (neutral density filter), an IR filter (infrared cut-off filter), etc. are used.

[0390] In Table 6 below, the parameter values of the optical system of the sixth embodiment are shown.

[0391] (Table 6)

[0392] [Overall parameters]

[0393]

[0394] [Lens parameters]

[0395]

[0396]

[0397] [Variable interval data during close-up photography]

[0398]

[0399] [Corresponding values of conditional expressions]

[0400] Conditional expressions (1), (1-1), (1-2), (1-3), (1-4)

[0401] νdLZ = 26.84

[0402] Conditional expressions (2), (2-1)

[0403] θgFLZ+(0.00316×νdLZ) = 0.7168

[0404] Conditional expression (3)

[0405] ndLZ+(0.01425×νdLZ) = 2.042

[0406] Conditional expression (4)

[0407] ndLZ+(0.00787×νdLZ) = 1.871

[0408] Conditional expressions (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0409] ndLZ = 1.659398

[0410] Conditional expression (6)

[0411] DLZ = 6.2000

[0412] Conditional expression (7)

[0413] ndLZ-(0.040×νdLZ-2.470)×νdLZ = 39.139

[0414] Conditional expression (8)

[0415] ndLZ-(0.020×νdLZ-1.080)×νdLZ = 16.239

[0416] Figure 12 These are aberration diagrams in the infinity focus state of the optical system of the sixth embodiment. From each aberration diagram, it can be seen that the optical system of the sixth embodiment corrects each aberration well and has excellent imaging performance.

[0417] (Seventh embodiment)

[0418] Use Figures 13 - 14 and Table 7 to illustrate the seventh embodiment. Figure 13This is a diagram showing the lens structure in the infinity focus state of the optical system according to the 7th embodiment of the present embodiment. The optical system LS(7) of the 7th embodiment is composed of a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, and a third lens group G3 having a positive optical power, which are arranged in order from the object side. When focusing from an infinite object to a close (finite distance) object, the second lens group G2 moves axially toward the image side. The aperture stop S is arranged near the object side of the third lens group G3 and is fixed relative to the image plane I during focusing, like the first lens group G1 and the third lens group G3.

[0419] The first lens group G1 is composed of a positive meniscus lens L11 with its convex surface facing the object side, a cemented lens composed of a biconvex positive lens L12 and a biconcave negative lens L13, arranged in order from the object side, a biconvex positive lens L14, and a cemented lens composed of a negative meniscus lens L15 with its convex surface facing the object side and a positive meniscus lens L16 with its convex surface facing the object side. In this embodiment, the positive meniscus lens L11 of the first lens group G1 corresponds to the object-side lens.

[0420] The second lens group G2 is composed of a cemented lens composed of a positive meniscus lens L21 with its concave surface facing the object side and a biconcave negative lens L22, and a cemented lens composed of a positive meniscus lens L23 with its concave surface facing the object side and a biconcave negative lens L24, arranged in order from the object side.

[0421] The third lens group G3 is composed of a biconvex positive lens L31, a negative meniscus lens L32 with its concave surface facing the object side, a positive meniscus lens L33 with its concave surface facing the object side, a biconvex positive lens L34, a negative meniscus lens L35 with its convex surface facing the object side, a cemented lens composed of a biconvex positive lens L36, a biconcave negative lens L37, and a biconvex positive lens L38, a positive meniscus lens L39 with its concave surface facing the object side, and a negative meniscus lens L40 with its concave surface facing the object side, arranged in order from the object side. In this embodiment, the negative meniscus lens L40 of the third lens group G3 corresponds to the image-side lens, and the positive lens L34 of the third lens group G3 corresponds to the lens that satisfies the conditional expressions (1) to (2), etc. The lens surface on the object side of the positive meniscus lens L39 is an aspherical surface.

[0422] The image plane I is arranged on the image side of the third lens group G3. An optical filter FL that can be inserted and replaced is arranged between the positive meniscus lens L33 and the positive lens L34 in the third lens group G3. As the optical filter FL that can be inserted and replaced, for example, an NC filter (neutral color filter), a color filter, a polarization filter, an ND filter (neutral density filter), an IR filter (infrared cut-off filter), etc. are used.

[0423] In Table 7 below, the values of the parameters of the optical system of the 7th embodiment are shown.

[0424] (Table 7)

[0425] [Overall parameters]

[0426]

[0427] [Lens parameters]

[0428]

[0429]

[0430] [Aspherical data]

[0431] 34th surface

[0432] κ = 1.0000

[0433] A4 = 8.36373E-06, A6 = 2.40160E-09, A8 = 0.00000E+00, A10 = 0.00000E+00

[0434] [Variable interval data during close-up photography]

[0435]

[0436] [Conditional formula corresponding values]

[0437] Conditional formulas (1), (1-1), (1-2), (1-3), (1-4)

[0438] νdLZ = 31.26

[0439] Conditional formulas (2), (2-1)

[0440] θgFLZ+(0.00316×νdLZ) = 0.7168

[0441] Conditional formula (3)

[0442] ndLZ+(0.01425×νdLZ) = 2.057

[0443] Conditional formula (4)

[0444] ndLZ+(0.00787×νdLZ) = 1.858

[0445] Conditional formulas (5), (5-1), (5-2), (5-3), (5-4), (5-5)

[0446] ndLZ = 1.611553

[0447] Conditional expression (6)

[0448] DLZ = 5.0000

[0449] Conditional expression (7)

[0450] ndLZ - (0.040 × νdLZ - 2.470) × νdLZ = 39.736

[0451] Conditional expression (8)

[0452] ndLZ - (0.020 × νdLZ - 1.080) × νdLZ = 15.829

[0453] Figure 14 These are aberration diagrams in the infinity focus state of the optical system of the seventh embodiment. From each aberration diagram, it can be seen that the optical system of the seventh embodiment corrects each aberration well and has excellent imaging performance.

[0454] According to the above embodiments, an optical system can be realized as follows: In the correction of chromatic aberration, in addition to primary achromatism, secondary spectrum is also corrected well.

[0455] Here, the above embodiments show a specific example of the present invention, and the present invention is not limited thereto.

[0456] In addition, the following content can be appropriately adopted within the range that does not damage the optical performance of the optical system of the present embodiment.

[0457] The focusing lens group represents a part having at least one lens separated by an air interval that changes when focusing is performed. That is, it can also be a focusing lens group that moves one or more lens groups, or a partial lens group in the optical axis direction to perform focusing from an infinite object to a close object. This focusing lens group can also be applied to autofocus and is also suitable for motor drive for autofocus (using an ultrasonic motor, etc.).

[0458] In the first and second embodiments of the optical system of the present embodiment, although a structure having an anti - shake function is shown, the present application is not limited thereto, and it can also be a structure without an anti - shake function. In addition, for other embodiments without an anti - shake function, it can also be a structure having an anti - shake function.

[0459] The lens surface can be formed by a spherical surface or a plane surface, or can be formed by an aspherical surface. When the lens surface is a spherical surface or a plane surface, lens processing and assembly adjustment become easy, and deterioration of optical performance caused by errors in processing and assembly adjustment is prevented, so it is preferred. In addition, even in the case of image plane shift, deterioration of the rendering performance is small, so it is preferred.

[0460] When the lens surface is an aspherical surface, the aspherical surface can be any one of an aspherical surface based on grinding, a glass molded aspherical surface formed by molding glass into an aspherical shape using a mold, and a composite aspherical surface formed by molding resin into an aspherical shape on the surface of glass. In addition, the lens surface can also be a diffractive surface, and the lens can also be a gradient index lens (GRIN lens) or a plastic lens.

[0461] On each lens surface, in order to reduce glare and ghosting and achieve high-contrast optical performance, an antireflection film having a high transmittance in a wide wavelength region can also be applied. Thereby, it is possible to reduce glare and ghosting and achieve high optical performance with high contrast.

[0462] Reference Numeral Explanation

[0463] G1 First lens group G2 Second lens group

[0464] G3 Third lens group G4 Fourth lens group

[0465] G5 Fifth lens group G6 Sixth lens group

[0466] I Image plane S Aperture stop

Claims

1. An optical system, wherein, the optical system is composed of a first lens group having a negative optical power and a second lens group having a positive optical power, which are arranged in sequence from the object side, and the second lens group includes a lens that satisfies the following conditional expressions; alternatively, the optical system is composed of a first lens group having a positive optical power, a second lens group having a negative optical power, and a third lens group having a positive optical power, which are arranged in sequence from the object side, and the second lens group includes a lens that satisfies the following conditional expressions; alternatively, the optical system is composed of a first lens group having a positive optical power, a second lens group having a negative optical power, and a third lens group having a positive optical power, which are arranged in sequence from the object side, and the third lens group includes a lens that satisfies the following conditional expressions; alternatively, the optical system is composed of a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, a fourth lens group having a positive optical power, a fifth lens group having a negative optical power, and a sixth lens group having a negative optical power, which are arranged in sequence from the object side, and the second lens group and the sixth lens group include a lens that satisfies the following conditional expressions; The following conditional expressions are: 25.0 < νdLZ < 29.5 0.708 < θgFLZ + (0.00316 × νdLZ) ≤ 0.7179 1.65 < ndLZ 1.871 ≤ ndLZ + (0.00787 × νdLZ) wherein, νdLZ: Abbe number of the lens based on the d-line θgFLZ: Relative partial dispersion of the lens, which is defined by the following formula when the refractive index of the lens for the g-line is ngLZ, the refractive index of the lens for the F-line is nFLZ, and the refractive index of the lens for the C-line is nCLZ θgFLZ = (ngLZ - nFLZ) / (nFLZ - nCLZ), ndLZ: Refractive index of the lens for the d-line 2. The optical system according to claim 1, wherein, The lens satisfies the following conditional formula: ndLZ + (0.01425 × νdLZ) < 2.12 where ndLZ: Refractive index of the lens for the d-line 3. The optical system according to claim 1 or 2, wherein, The lens satisfies the following conditional formula: DLZ > 0.80 where DLZ: Thickness [mm] on the optical axis of the lens 4. The optical system according to claim 1 or 2, wherein, The optical system includes an object-side lens disposed on the object side closest to the object The lens is disposed on the image side with respect to the object-side lens 5. The optical system according to claim 1 or 2, wherein, The optical system includes an image-side lens disposed on the image side closest to the image The lens is disposed on the object side with respect to the image-side lens 6. The optical system according to claim 1 or 2, wherein, The lens is a glass lens 7. An optical device configured to include the optical system according to any one of claims 1 to 6.

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