Optical lens system

Abstract

To provide an optical lens system which offers a significant reduction in total length while maintaining good optical performance.SOLUTION: An optical lens system provided herein consists of a first lens group G1 having positive refractive power, an aperture stop STO, and a second lens group G2 having positive refractive power arranged in order from the object side, where the first lens group G1 comprises, in order from the object side, two or more successive positive lenses L1, L2 having convex surfaces on the object side and one negative lens L3 having a concave surface on the image side, while the second lens group G2 comprises, in order from the object side, a cemented lens L6 consisting of a negative meniscus lens L4 having a convex surface on the object side and a positive lens L5 cemented to the negative meniscus lens L4, one or more positive lenses L7, and a negative lens L8 with both surfaces that are concave toward the object side located on the most image side.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical lens system for use in an interchangeable lens camera. [Background technology]

[0002] In optical lens systems used in interchangeable lens cameras, there is a demand for further miniaturization of those with a standard angle of view (total angle of view of approximately 46.0 to 48.0°). For example, Patent Document 1 (Japanese Patent No. 5582905) discloses an optical lens system that includes, in order from the object side to the image side, a first lens group with a positive refractive index, a second lens group with a positive or negative refractive index, and a third lens group with a positive refractive index. The first lens group is composed of, in order from the object side to the image side, a lens component with a positive refractive index and a cemented lens component having a positive lens and a negative lens and having a convex surface facing the object side. An aperture is provided between the object-side surface of the first lens group and the object-side surface of the second lens group. The lens closest to the object in the first lens group and the lens closest to the image in the third lens group are always fixed, and only the second lens group moves along the optical axis when focusing from a long distance to a close distance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5582905 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 states that the adoption of the above-described configuration is advantageous for soundproofing and dustproofing, makes it easier to keep the diameter small, and makes it easier to ensure optical performance. However, with the configuration as disclosed in Patent Document 1, there is a limit to how much the overall length can be shortened, and there is a need for a configuration that can further shorten the overall length. [Means for solving the problem]

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an optical lens system that can achieve a significant reduction in overall length while maintaining optical performance.

[0006] The present invention solves the above problems by the solution means described below as one embodiment. That is, the lens comprises, in order from the object side, a first lens group having positive refractive power, an aperture stop, and a second lens group having positive refractive power, the first lens group having, in order from the object side, two or more consecutive positive lenses each with a convex surface facing the object side, and one negative lens with a concave surface facing the image side, and the second lens group having, in order from the object side, a negative meniscus lens with a convex surface facing the object side and a cemented lens which is a positive lens cemented to this negative meniscus lens, one or more lenses of positive lens components, and a negative lens closest to the image side, both of whose concave surfaces face the object side.

[0007] As with the above configuration, both the first and second lens groups are made up of positive lens components, which contributes to compactness. Furthermore, by using a Gaussian configuration for the first lens group, it becomes a strong telephoto type, which contributes to shortening the overall length. Furthermore, by arranging the lens in the second lens group with its convex surface facing the object side, it is possible to create a lens group with a strong convex component, which leads to a significant reduction in the overall length. Furthermore, by using a negative lens as the lens closest to the image side in the second lens group, the back focus can be shortened, which also contributes to shortening the overall length.

[0008] The first lens group does not include a cemented lens. If a cemented lens were to be included in the first lens group, it would increase the size of the object side and hinder compactness, but this configuration contributes to compactness, and the increased number of refractive surfaces makes it possible to correct spherical aberration and coma.

[0009] The optical system is also characterized in that it comprises an air lens having a convex meniscus shape with a convex surface facing the object side, on the object side of the negative lens closest to the image side in the first lens group. With this configuration, the convex meniscus air lens acts as an apparent negative lens, and the first lens group has a convex-convex-concave-concave Gaussian configuration, making it a strong telephoto type, which contributes to shortening the overall length.

[0010] The optical system is also characterized in that any one of the positive lenses in the first lens group satisfies the following conditional expression: Gr1p-ΔPgF>0.015 where Gr1p-ΔPgF is the largest ΔPgF value among the positive anomalous partial dispersion of the first lens group, ΔPgF is PgF-0.64833+0.00180νd, where g represents the anomalous partial dispersion between the F-lines, PgF is (ng-nF) / (nF-nC), where g represents the partial dispersion ratio between the F-lines, nC is the refractive index at the C-line (wavelength λ=656.27nm), nF is the refractive index at the F-line (wavelength λ=486.13nm), and ng is the refractive index at the g-line (wavelength λ=435.83nm). In this way, chromatic aberration can be corrected by using a positive lens having positive anomalous partial dispersion.

[0011] The optical system is also characterized in that any one of the positive lenses in the first lens group satisfies the following conditional expression: Gr1p-nd>1.90, where Gr1p-nd is the refractive index of the d line (wavelength λ=587.56 nm). In this way, if the refractive index of the positive lens is high, spherical aberration and coma can be corrected well, which contributes to size reduction while improving optical performance.

[0012] The optical system is characterized in that the following condition is satisfied, where the composite focal length of the cemented lens in the second lens group is f21 and the focal length of the entire optical lens system is f. f / f21>1.15

[0013] The optical system is also characterized in that any one of the positive lenses in the second lens group satisfies the following conditional expression: 44.30>Gr2p-νd>28.40 1.790>Gr2p-nd>1.610 Here, Gr2P-νd is the Abbe number of the d-line (wavelength λ=587.56 nm), and Gr2P-nd is the refractive index of the d-line (wavelength λ=587.56 nm). By using such a positive lens, chromatic aberration can be corrected and high performance can be achieved.

[0014] Furthermore, when the distance on the optical axis from the lens surface closest to the object to the image plane is defined as LH, and the distance on the optical axis from the lens surface closest to the image plane to the image plane is defined as L-BF, the optical system is characterized in that LH / L-BF>3.2 is satisfied. This makes the back focus shorter relative to the overall length, contributing to miniaturization.

[0015] Furthermore, when the focal length of the entire lens is f and the total optical length is LH, the lens is characterized in that LH / f<1.30 is satisfied. This reduces the overall length of the lens relative to its focal length, contributing to miniaturization.

[0016] Furthermore, all of the lens surfaces are spherical.

[0017] Furthermore, when focusing on a close-up object, all of the lenses are moved. With this configuration, there is no need to provide a lens spacing between the first lens group and the second lens group for focusing, which reduces the overall length of the lens and contributes to miniaturization. [Effects of the Invention]

[0018] It is possible to significantly reduce the overall length while maintaining optical performance. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an optical lens system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal aberration diagram of the optical lens system according to the first embodiment of the present invention at infinity. [Figure 3]FIG. 10 is a diagram illustrating the configuration of an optical lens system according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a longitudinal aberration diagram of the optical lens system according to the second embodiment of the present invention at infinity. [Figure 5] FIG. 10 is a diagram illustrating the configuration of an optical lens system according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a longitudinal aberration diagram of the optical lens system according to the third embodiment of the present invention at infinity. DETAILED DESCRIPTION OF THE INVENTION

[0020] Each embodiment will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram of an optical lens system 100 according to a first embodiment of the present invention. FIG. 2 is a longitudinal aberration diagram of the optical lens system 100 according to the first embodiment of the present invention at infinity. FIG. 3 is a configuration diagram of an optical lens system 200 according to a second embodiment of the present invention. FIG. 4 is a longitudinal aberration diagram of the optical lens system 200 according to the second embodiment of the present invention at infinity. FIG. 5 is a configuration diagram of an optical lens system 300 according to a third embodiment of the present invention. FIG. 6 is a longitudinal aberration diagram of the optical lens system 300 according to the third embodiment of the present invention at infinity.

[0021] Legends for the C-line (wavelength 656.27 nm), d-line (wavelength 587.56 nm), and g-line (wavelength 435.83 nm) are provided in the upper right corner of each of Figures 2, 4, and 6. Note that in all figures used to explain each embodiment, members having the same functions are denoted by the same reference numerals, and repeated explanations may be omitted.

[0022] The optical lens systems 100, 200, and 300 in the respective embodiments are, for example, interchangeable imaging lenses used in a photo camera or video camera. As shown in FIGS. 1, 3 and 5, the optical lens systems 100, 200 and 300 include a first lens group G1, an aperture stop STO and a second lens group G2 on the optical axis from an object OBJ to an image plane IMG.

[0023] Furthermore, the optical lens systems 100, 200, and 300 in each embodiment are configured so that when focusing from infinity to a close distance, the entire optical system is moved toward the object side to perform focusing.

[0024] 1, 3, and 5, the surfaces of the lenses are numbered for convenience, but the surface numbers do not necessarily correspond between the embodiments. Also, the cemented surfaces of cemented lenses are assigned the same number. Furthermore, because the aperture stop STO is counted as a virtual surface, the consecutive surface numbers are omitted.

[0025] (First embodiment) In the first embodiment, an imaging lens 100 having a focal length f of the entire system of 48.455 mm, an F-number of 2.254, and a half angle of view ω of 23.797° will be described by way of example in FIG.

[0026] The imaging lens 100 of this embodiment includes, in order on the optical axis from the object OBJ to the image plane IMG, a first lens group G1 having positive refractive power, an aperture stop STO, and a second lens group G2 having positive refractive power. As described above, the first lens group G1 and the second lens group G2 both have positive refractive power, which contributes to the miniaturization of the entire imaging lens 100.

[0027] The first lens group G1 comprises, in order from the object OBJ, a positive meniscus lens L1 with a convex surface facing the object OBJ, a positive meniscus lens L2 with a convex surface facing the object OBJ, and a negative meniscus lens L3 with a concave surface facing the image plane IMG. The gap formed between the positive meniscus lens L2 and the negative meniscus lens L3 is configured as an air lens AL1.

[0028] The air lens AL1 is formed between a lens surface 4 of the positive meniscus lens L2 on the image plane IMG side and a lens surface 5 of the negative meniscus lens L3 on the object OBJ side, and has a positive meniscus shape with the convex surface facing the object OBJ side. The air lens AL1 acts as an apparent negative lens, and by making the first lens group G1 a convex-convex-concave-concave Gaussian configuration, it becomes a strong telephoto type (telephoto type), which can contribute to shortening the overall length.

[0029] The second lens group G2 is arranged closer to the image plane IMG than the aperture stop STO, and includes, in order from the object OBJ, a cemented lens L6 made up of a negative meniscus lens L4 with its convex surface facing the object OBJ and a positive meniscus lens L5 cemented to the negative meniscus lens L4 with its convex surface facing the object OBJ, a positive meniscus lens L7 with its concave surface facing the object OBJ, and a negative meniscus lens L8 with both concave surfaces facing the object OBJ. In this way, by arranging a cemented lens with its convex surface facing the object OBJ side in the second lens group G2 closest to the object OBJ, a strong convex component can be created, which leads to a significant reduction in the overall length. In addition, by making the lens in the second lens group G2 closest to the image plane IMG a negative lens, the back focal length can be shortened, which also contributes to a reduction in the overall length.

[0030] Table 1 shows a summary of various data for the first embodiment. [Table 1]

[0031] In Table 1, LG1 is the overall length of the first lens group G1, and LG2 is the overall length of the second lens group G2. f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f21 is the focal length of the cemented lens L6 immediately after the aperture stop STO, f22 is the focal length of the positive meniscus lens L7 immediately after the cemented lens, and f23 is the focal length of the negative meniscus lens L8 closest to the image plane IMG.

[0032] Also, Gr1P-ΔPgF is the positive anomalous partial dispersion of the first lens group G1, and Gr1P-nd is the refractive index of the d-line (wavelength λ=587.56 nm) of any of the positive lenses in the first lens group G1. Gr2P-νd is the Abbe number of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm), and Gr2P-nd is the refractive index of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm).

[0033] According to the first embodiment, Gr1P-ΔPgF=0.0374, which satisfies Gr1p-ΔPgF>0.015, and therefore chromatic aberration can be corrected.

[0034] Furthermore, according to the first embodiment, Gr1P-nd=2.00100, which satisfies Gr1P-nd>1.90, making it possible to effectively correct spherical aberration and coma, thereby contributing to size reduction while improving optical performance.

[0035] Furthermore, according to the first embodiment, f / f21=1.18, which satisfies f / f21>1.15, which can contribute to shortening the overall length.

[0036] Furthermore, according to the first embodiment, LH / L-BF=4.04, which satisfies LH / L-BF>3.2, and therefore L-BF can be made shorter, which contributes to shortening the overall length. Furthermore, according to the first embodiment, LH / f=1.17, which satisfies LH / f<1.30, which makes it possible to further reduce the telephoto ratio and contribute to shortening the overall length.

[0037] Next, Table 2 shows the lens data of the optical lens system 100 according to the first embodiment shown in FIG.

[0038] [Table 2]

[0039] Table 2 shows the radius of curvature R (mm) corresponding to the virtual surface and lens surface counted from the object OBJ side, the surface spacing D (mm) on the optical axis, the refractive index nd of the lens, and the Abbe number νd of the lens. When the lens surface is convex with respect to the object OBJ, the radius of curvature R is positive, and when the lens surface is concave with respect to the object OBJ, the radius of curvature R is negative. In addition, nd and vd are values ​​for the d-line (wavelength λ=587.56 nm). Also, D is the distance from one surface to the next surface. Furthermore, the blanks in nd and νd indicate air.

[0040] As shown in Table 2, all lens surfaces in the first embodiment are spherical.

[0041] [Table 3]

[0042] Table 3 shows the variable spacing between lenses.

[0043] Next, FIG. 2 shows spherical aberration, astigmatism, and distortion in the optical lens system 100. The scales are ±0.50 mm, ±0.50 mm, and ±5.00%. As shown in Figure 2, it can be confirmed that good aberration correction is achieved in all cases.

[0044] (Second embodiment) Next, a second embodiment will be described using an imaging lens 200 shown in FIG. 3, in which the focal length of the entire system is f=48.700 mm, the F-number is 2.265, and the half angle of view ω=23.623°.

[0045] The imaging lens 200 in this embodiment includes, in order on the optical axis from the object OBJ to the image plane IMG, a first lens group G1 having positive refractive power, an aperture stop STO, and a second lens group G2 having positive refractive power. As described above, both the first lens group G1 and the second lens group G2 have positive refractive power, which contributes to the miniaturization of the entire imaging lens 200.

[0046] The first lens group G1 comprises, in order from the object OBJ, a positive meniscus lens L9 with its convex surface facing the object OBJ side, a positive meniscus lens L10 with its convex surface facing the object OBJ side, a positive meniscus lens L11 with its convex surface facing the object OBJ side, and a negative meniscus lens L12 with its concave surface facing the image plane IMG side. The gap formed between the positive meniscus lens L11 and the negative meniscus lens L12 is configured as an air lens AL2.

[0047] The air lens AL2 is formed between a lens surface 6 of the positive meniscus lens L11 on the image plane IMG side and a lens surface 7 of the negative meniscus lens L12 on the object OBJ side, and has a positive meniscus shape with its convex surface facing the object OBJ side. The air lens AL2 acts as an apparent negative lens, and by making the first lens group G1 a convex-convex-concave-concave Gaussian configuration, it becomes a strong telephoto type (telephoto type), which can contribute to shortening the overall length.

[0048] The second lens group G2 is arranged closer to the image plane IMG than the aperture stop STO, and includes, in order from the object OBJ, a cemented lens L15 made up of a negative meniscus lens L13 with its convex surface facing the object OBJ and a positive meniscus lens L14 cemented to the negative meniscus lens L13 with its convex surface facing the object OBJ, a positive meniscus lens L16 with its concave surface facing the object OBJ, and a negative meniscus lens L17 with both concave surfaces facing the object OBJ. In this way, by arranging a cemented lens with its convex surface facing the object OBJ side in the second lens group G2 closest to the object OBJ, a strong convex component can be created, which leads to a significant reduction in the overall length. In addition, by making the lens in the second lens group G2 closest to the image plane IMG a negative lens, the back focal length can be shortened, which also contributes to a reduction in the overall length.

[0049] Table 4 shows a summary of various data for the second embodiment. [Table 4]

[0050] In Table 4, LG1 is the overall length of the first lens group G1, and LG2 is the overall length of the second lens group G2. f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f21 is the focal length of the cemented lens L15 immediately after the aperture stop STO, f22 is the focal length of the positive meniscus lens L16 immediately after the cemented lens L15, and f23 is the focal length of the negative meniscus lens L17 closest to the image plane IMG.

[0051] Also, Gr1P-ΔPgF is the positive anomalous partial dispersion of the first lens group G1, and Gr1P-nd is the refractive index of the d-line (wavelength λ=587.56 nm) of any of the positive lenses in the first lens group G1. Gr2P-νd is the Abbe number of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm), and Gr2P-nd is the refractive index of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm).

[0052] According to the second embodiment, Gr1P-ΔPgF=0.0374, which satisfies Gr1p-ΔPgF>0.015, and therefore chromatic aberration can be corrected.

[0053] Furthermore, according to the second embodiment, Gr1P-nd=1.90043, which satisfies Gr1P-nd>1.90, making it possible to effectively correct spherical aberration and coma, thereby contributing to size reduction while improving optical performance.

[0054] Furthermore, according to the second embodiment, f / f21=1.26, which satisfies f / f21>1.15, which can contribute to shortening the overall length.

[0055] Furthermore, according to the second embodiment, LH / L-BF=3.23, which satisfies LH / L-BF>3.2, can be further shortened L-BF, which contributes to shortening the overall length. Furthermore, according to the second embodiment, LH / f=1.15, which satisfies LH / f<1.30, which makes it possible to further reduce the telephoto ratio and contribute to shortening the overall length.

[0056] Next, Table 5 shows lens data for the optical lens system 200 according to the second embodiment shown in FIG. [Table 5]

[0057] Table 5 shows the radius of curvature R (mm) corresponding to the virtual surface and lens surface counted from the object OBJ side, the surface spacing D (mm) on the optical axis, the refractive index nd of the lens, and the Abbe number νd of the lens. When the lens surface is convex with respect to the object OBJ, the radius of curvature R is positive, and when the lens surface is concave with respect to the object OBJ, the radius of curvature R is negative. In addition, nd and vd are values ​​for the d-line (wavelength λ=587.56 nm). Also, D is the distance from one surface to the next surface. Furthermore, the blanks in nd and νd indicate air.

[0058] As shown in Table 5, all lens surfaces in the second embodiment are spherical.

[0059] [Table 6]

[0060] Table 6 shows the variable spacing between lenses.

[0061] Next, FIG. 4 shows spherical aberration, astigmatism, and distortion in the optical lens system 200. The scales are ±0.50 mm, ±0.50 mm, and ±5.00%. As shown in Figure 4, it can be confirmed that good aberration correction is achieved in all cases.

[0062] (Third embodiment) Next, a third embodiment will be described using an imaging lens 300 shown in FIG. 5, in which the focal length of the entire system is f=48.765 mm, the F-number is 2.268, and the half angle of view ω=23.604°.

[0063] The imaging lens 300 in this embodiment includes, in order on the optical axis from the object OBJ to the image plane IMG, a first lens group G1 having positive refractive power, an aperture stop STO, and a second lens group G2 having positive refractive power. As described above, both the first lens group G1 and the second lens group G2 have positive refractive power, which contributes to the miniaturization of the entire imaging lens 200.

[0064] The first lens group G1 comprises, in order from the object OBJ, a positive meniscus lens L18 with its convex surface facing the object OBJ, a positive meniscus lens L19 with its convex surface facing the object OBJ, and a negative meniscus lens L20 with its concave surface facing the image plane IMG. The gap formed between the positive meniscus lens L19 and the negative meniscus lens L20 is configured as an air lens AL3.

[0065] The air lens AL3 is formed between a lens surface 4 of the positive meniscus lens L19 on the image plane IMG side and a lens surface 5 of the negative meniscus lens L20 on the object OBJ side, and has a positive meniscus shape with the convex surface facing the object OBJ side. The air lens AL3 acts as an apparent negative lens, and by making the first lens group G1 a convex-convex-concave-concave Gaussian configuration, it becomes a strong telephoto type (telephoto type), which can contribute to shortening the overall length.

[0066] The second lens group G2 is arranged closer to the image plane IMG than the aperture stop STO, and includes, in order from the object OBJ, a cemented lens L23 made up of a negative meniscus lens L21 with its convex surface facing the object OBJ and a biconvex lens L20 cemented to the negative meniscus lens L19, a cemented lens L26 made up of a biconcave lens L24 and a biconvex lens L25 cemented to the biconcave lens L24, and a negative meniscus lens L27 with concave surfaces on both sides facing the object OBJ. In this way, by arranging the cemented lens L23 with its convex surface facing the object OBJ side in the second lens group G2 closest to the object OBJ, a strong convex component can be created, which leads to a significant reduction in the overall length. In addition, by making the lens in the second lens group G2 closest to the image plane IMG a negative lens, the back focal length can be shortened, which also contributes to a reduction in the overall length.

[0067] Table 7 shows a summary of various data for the third embodiment. [Table 7]

[0068] In Table 7, LG1 is the overall length of the first lens group G1, and LG2 is the overall length of the second lens group G2. f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f21 is the focal length of the cemented lens L23 immediately after the aperture stop STO, f22 is the focal length of the cemented lens L26, and f23 is the focal length of the negative meniscus lens L27 closest to the image plane IMG.

[0069] Also, Gr1P-ΔPgF is the positive anomalous partial dispersion of the first lens group G1, and Gr1P-nd is the refractive index of the d-line (wavelength λ=587.56 nm) of any of the positive lenses in the first lens group G1. Gr2P-νd is the Abbe number of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm), and Gr2P-nd is the refractive index of one of the positive lenses in the second lens group G2 at the d-line (wavelength λ=587.56 nm).

[0070] According to the third embodiment, Gr1P-ΔPgF=0.0374, which satisfies Gr1p-ΔPgF>0.015, making it possible to correct chromatic aberration.

[0071] Furthermore, according to the third embodiment, Gr1P-nd=1.90043, which satisfies Gr1P-nd>1.90, making it possible to effectively correct spherical aberration and coma, thereby contributing to size reduction while improving optical performance.

[0072] Furthermore, according to the third embodiment, f / f21=1.28, which satisfies f / f21>1.15, which can contribute to shortening the overall length.

[0073] Furthermore, according to the third embodiment, LH / L-BF=3.43, which satisfies LH / L-BF>3.2, and therefore L-BF can be made shorter, which contributes to shortening the overall length. Furthermore, according to the second embodiment, LH / f=1.15, which satisfies LH / f<1.30, which makes it possible to further reduce the telephoto ratio and contribute to shortening the overall length.

[0074] Next, Table 8 shows lens data for the optical lens system 300 according to the third embodiment shown in FIG. [Table 8]

[0075] Table 8 shows the radius of curvature R (mm) corresponding to the virtual surface and lens surface counted from the object OBJ side, the surface spacing D (mm) on the optical axis, the refractive index nd of the lens, and the Abbe number νd of the lens. When the lens surface is convex with respect to the object OBJ, the radius of curvature R is positive, and when the lens surface is concave with respect to the object OBJ, the radius of curvature R is negative. In addition, nd and vd are values ​​for the d-line (wavelength λ=587.56 nm). Also, D is the distance from one surface to the next surface. Furthermore, the blanks in nd and νd indicate air.

[0076] As shown in Table 8, all lens surfaces in the third embodiment are spherical.

[0077] [Table 9]

[0078] Table 9 shows the variable spacing between lenses.

[0079] Next, FIG. 6 shows spherical aberration, astigmatism, and distortion in the optical lens system 300. The scales are ±0.50 mm, ±0.50 mm, and ±5.00%. As shown in Figure 6, it can be confirmed that good aberration correction is achieved in all cases.

[0080] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention. [Explanation of symbols]

[0081] 100 Optical Lens System 200 Optical Lens System 300 Optical Lens System AL1 Air Lens AL2 Air Lens AL3 Air Lens G1 Group 1 G2 2nd group L1 positive meniscus lens L2 positive meniscus lens L3 negative meniscus lens L4 negative meniscus lens L5 positive meniscus lens L6 cemented lens L7 positive meniscus lens L8 negative meniscus lens L9 positive meniscus lens L10 positive meniscus lens L11 positive meniscus lens L12 negative meniscus lens L13 negative meniscus lens L14 positive meniscus lens L15 cemented lens L16 positive meniscus lens L17 negative meniscus lens L18 positive meniscus lens L19 positive meniscus lens L20 negative meniscus lens L21 negative meniscus lens L22 biconvex lens L23 cemented lens L24 biconcave lens L25 biconvex lens L26 cemented lens L27 negative meniscus lens STO aperture stop OBJ object IMG Image plane

Claims

1. The lens comprises, in order from the object side, a first lens group having positive refractive power, an aperture stop, and a second lens group having positive refractive power, The first lens group is The lens has, in order from the object side, two or more consecutive positive lenses each having a convex surface facing the object side, and one negative lens each having a concave surface facing the image side, The second lens group is The optical lens system has, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a cemented lens which is a positive lens cemented to the negative meniscus lens, one or more lenses of positive lens components, and a negative lens closest to the image side, both of whose concave surfaces face the object side.

2. 2. The optical lens system according to claim 1, wherein said first lens group does not include any cemented lens.

3. 2. The optical lens system according to claim 1, further comprising a convex meniscus air lens with a convex surface facing the object side, on the object side of the negative lens closest to the image side in said first lens group.

4. 2. The optical lens system according to claim 1, wherein any one of the positive lenses in the first lens group satisfies the following condition: 1 / (f / f<f<f) / f / f< ... Gr1p-ΔPgF>0.015 where Gr1p-ΔPgF is the value of ΔPgF, which is the largest positive anomalous partial dispersion of the first lens group; ΔPgF is PgF-0.64833+0.00180νd, and represents the anomalous partial dispersion between the g and F lines; PgF is (ng-nF) / (nF-nC), and represents the partial dispersion ratio between the g and F lines; nC is the refractive index at the C line (wavelength λ=656.27 nm); nF is the refractive index at the F line (wavelength λ=486.13 nm); and ng is the refractive index at the g line (wavelength λ=435.83 nm).

5. 2. The optical lens system according to claim 1, wherein any one of the positive lenses in the first lens group satisfies the following condition: 1 / (f / f<f<f) / f / f< ... Gr1p-nd>1.90 Here, Gr1p-nd is the refractive index of the d-line (wavelength λ=587.56 nm).

6. 2. The optical lens system according to claim 1, wherein the following condition is satisfied: f21 is a composite focal length of the cemented lens in the second lens group; and f is a focal length of the entire optical lens system. f / f21>1.15

7. 2. The optical lens system according to claim 1, wherein any one of the positive lenses in the second lens group satisfies the following condition: 1 / (f / f<f<f) / f / f< ... 44.30>Gr2p-νd>28.40 1.790>Gr2p-nd>1.610 Here, Gr2P-νd is the Abbe number of the d-line (wavelength λ=587.56 nm), and Gr2P-nd is the refractive index of the d-line (wavelength λ=587.56 nm).

8. When the distance on the optical axis from the lens surface closest to the object to the image plane is L-H, and the distance on the optical axis from the lens surface closest to the image to the image plane is L-BF, L-H / L-BF>3.2 2. The optical lens system according to claim 1, wherein

9. When the focal length of the entire lens is f and the total optical length is L-H, L-H / f<1.30 2. The optical lens system according to claim 1, wherein

10. 2. The optical lens system of claim 1, wherein all lens surfaces are spherical.

11. 2. The optical lens system according to claim 1, wherein all lenses are moved when focusing on a close-distance object.

Images