Optical system and imaging device, lens device having the same

Abstract

To provide a compact optical system that combines high optical performance with ease of molding. [Solution] An optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, wherein the optical system has at least 10 lenses, the rear group includes an aspherical lens having an inflection point, and satisfies a predetermined condition when the focal length of the entire optical system is f, the focal length of the front group is f1, the maximum image height of the optical system is ImgH, and the total optical length of the optical system is L.

Description

[Technical Field]

[0001] The disclosures herein relate to optical systems and are suitable for digital still cameras, digital video cameras, surveillance cameras, in-vehicle cameras, smartphone cameras, and the like. [Background technology]

[0002] In wide-angle optical systems, distortion aberrations occurring in the optical system can be corrected by arranging the lens group on the object side relative to the aperture. Patent Document 1 discloses a wide-angle optical system in which a front lens group with negative refractive power, an aperture diaphragm, and a rear lens group with positive refractive power are arranged in order from the object side. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-184065 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, the small optical systems disclosed in the aforementioned patent documents have the problem that the negative refractive power of the front lens group is small, which makes it difficult to mold lenses with complex shapes. [Means for solving the problem]

[0005] One aspect of the present invention is an optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, wherein the optical system has at least 10 lenses, and the optical system includes an aspherical lens having an inflection point, and when the focal length of the entire optical system is f, the focal length of the front group is f1, the maximum image height of the optical system is ImgH, and the total optical length of the optical system is L, -2.98 <f1 / f<0.00 0.40 <ImgH / L It is characterized by satisfying the following conditional expression.

[0006] Furthermore, as another aspect of the present invention, an optical system is provided which has a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, wherein the front group includes at least three lenses, the optical system includes an aspherical lens having an inflection point, and when the focal length of the entire optical system is f and the focal length of the front group is f1, -2.98 <f1 / f<0.00 It is characterized by satisfying the following conditional expression. [Effects of the Invention]

[0007] We can provide an optical system that achieves both high optical performance and moldability. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view of the optical system of Example 1 at infinity focus. [Figure 2] Longitudinal aberration diagram corresponding to Example 1 [Figure 3] Cross-sectional view of the optical system of Example 2 at infinity focus. [Figure 4] Longitudinal aberration diagram corresponding to Example 2 [Figure 5] Cross-sectional view of the optical system of Example 3 at infinity focus. [Figure 6] Longitudinal aberration diagram corresponding to Example 3 [Figure 7] Cross-sectional view of the optical system of Example 4 at infinity focus. [Figure 8] Longitudinal aberration diagram corresponding to Example 4 [Figure 9] Schematic diagram of the hit point of off-axis rays on an optical surface. [Figure 10] Schematic diagram of an imaging device using the optical systems of Examples 1 to 4 [Figure 11] Schematic diagram of a lens device using the optical systems of Examples 1 to 4 [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same members are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0010] FIGS. 1, 3, 5, and 7 are cross-sectional views of the optical system L0 at infinity focus in Examples 1 to 4, respectively. The optical system L0 of each example is used in an imaging device such as a digital still camera, a digital video camera, a surveillance camera, or an in-vehicle camera.

[0011] In each cross-sectional view, the left side is the object side and the right side is the image side. The optical system L0 of each example has a plurality of lens groups. Note that, in this specification, the lens group refers to a collection of lenses separated by the aperture stop SP. Also, each lens group may be composed of one lens or a plurality of lenses. Further, each lens group may include an aspherical lens, a Fresnel lens, a metalens, a diffractive optical element, and the like.

[0012] In the optical system L0 of each example, Li represents the i-th (i is a natural number) lens group counted from the object side among the lens groups included in the optical system L0. Also, Gk represents the k-th (k is a natural number) lens counted from the object side among the lenses included in the optical system.

[0013] In the optical system L0 of each example, L1 (LF) represents the front group as a lens group disposed on the object side of the aperture stop. Also, L2 (LR) represents the rear group as a lens group disposed on the image side of the aperture stop.

[0014] In each cross-sectional view, SP is the aperture diaphragm. FL is an optical element corresponding to an optical filter, low-pass filter, infrared cut filter, etc. IP is the image plane, and when the optical system L0 of each embodiment is used as the imaging optical system of a digital still camera or digital video camera, the imaging plane of a solid-state image sensor such as a CCD sensor or CMOS sensor is positioned there. When the optical system L0 of each embodiment is used as the imaging optical system of a silver halide film camera, the image plane IP becomes the photosensitive surface corresponding to the film plane. The optical system of each embodiment may also be used as a projection lens for a projector, etc. In this case, the left side is the screen side, and the right side is the projected image side.

[0015] Figures 2, 4, 6, and 8 are aberration diagrams of the optical systems L0 of Examples 1 to 4 at infinity focus, respectively. In each figure, spherical aberration, astigmatism, distortion, and chromatic aberration are shown from left to right. In the spherical aberration diagram, Fno. is the F number, the solid line shows the amount of spherical aberration with respect to the d line (wavelength 587.6 nm), and the dashed line shows the amount of spherical aberration with respect to the g line (wavelength 435.8 nm). In the astigmatism diagram, the solid line shows the amount of field curvature of the sagittal image plane, and the dashed line shows the amount of field curvature of the meridional image plane. In the distortion diagram, the amount of distortion with respect to the d line is shown. In the chromatic aberration diagram, the chromatic aberration at the g line is shown. Also, ω is the half-angle of view [°].

[0016] Here, we will explain the off-axis focal length used in each embodiment. The off-axis focal length is the focal length of an off-axis ray that is incident on the optical axis at an angle ω[°] relative to the optical axis, passes through the center of the aperture diaphragm SP, and forms an image on the image side, when the maximum half-angle of view of the optical system L0 with an on-axis focal length of f0 is ω[°].

[0017] Figure 9 shows the method for calculating the off-axis focal length. In Figure 9, Gi is an optical surface such as a lens surface, and the direction of the optical axis on the optical surface is defined as the Z direction. Of the directions perpendicular to the Z direction, two mutually orthogonal directions are defined as the X direction and the Y direction. When the Z direction is parallel to the horizontal direction, the X direction is also parallel to the horizontal direction, and the Y direction is parallel to the vertical direction.

[0018] In Figure 9, the intersection point of the on-axis ray and the optical surface Gi is defined as hp_0. The intersection point of the off-axis ray incident at the maximum field of view ω[°] and the optical surface Gi is defined as the hit point hp_ω. Calculating the curvature near the off-axis principal ray at the hit point hp_ω reveals that this curvature differs depending on the azimuth angle. As described in Reference 1 below, the focal length for the off-axis principal ray can be determined by calculating the curvature at the hit point. (Reference 1) Keisuke Araki, "Development of Non-Coaxial Optical Systems for Imaging Systems," Optics, The Optical Society of Japan, June 2008, Vol. 37, No. 6, pp. 334-339.

[0019] Next, we will describe the characteristic configuration of the optical system L0 in each embodiment.

[0020] The optical system L0 in each embodiment has, in order from the object side, a front group L1 with negative refractive power, an aperture diaphragm SP, and a rear group L2. Because the front group L1 has negative refractive power, the optical system L0 has a so-called retrofocus type configuration, so the principal point is located on the image side and back focus can be secured. In addition, the optical system L0 can be miniaturized in the radial direction.

[0021] The optical system L0 of each embodiment includes an aspherical lens. Furthermore, in the optical system L0 of each embodiment, the lens surface of the aspherical lens included in the rear group L2 has an inflection point. An inflection point on the lens surface is a point where the sign of the refractive power of the lens changes from near the optical axis to the periphery of the lens surface. By including an aspherical lens with an inflection point, image field distortion and astigmatism can be effectively corrected.

[0022] As an example of an aspherical lens with an inflection point, the object-side lens surface of the aspherical lens is convex towards the object near the optical axis and concave towards the object at the periphery. Similarly, the image-side lens surface of the aspherical lens is concave towards the image near the optical axis and convex towards the image at the periphery. This allows for correction of Petzval sum near the optical axis while correcting astigmatism at the periphery. Furthermore, the object-side lens surface of the aspherical lens may be concave towards the object near the optical axis and convex towards the object at the periphery. Similarly, the image-side lens surface of the aspherical lens may be concave towards the image near the optical axis and convex towards the image at the periphery.

[0023] Furthermore, the optical system L0 of each embodiment is characterized in that, when the total focal length of the optical system L0 is f, it satisfies the following condition (1). -2.98 <f1 / f<0.00 (1)

[0024] Condition (1) specifies the relationship between the focal length of the front group L1 and the overall focal length of the optical system L0. Satisfying condition (1) allows for good correction of various aberrations while improving the moldability of the lenses constituting the front group L1. If the value falls below the lower limit of condition (1), the absolute value of the negative refractive power of the front group L1 becomes small. In this case, in order to achieve both distortion correction and field curvature correction, it is necessary to increase the thickness ratio of the lenses constituting the front group L1, which is undesirable because it reduces the moldability of the lenses. If the value exceeds the upper limit of condition (1), the front group L1 has a positive refractive power, making it difficult to correct distortion and field curvature, which is undesirable.

[0025] Furthermore, it is more preferable to set the numerical range of conditional expression (1) to the range of (1a) below. -2.80 <f1 / f<-1.00 (1a)

[0026] Furthermore, it is even more preferable to set the numerical range of conditional expression (1) to the range of (1b) below. -2.75 <f1 / f<-2.00 (1b)

[0027] Next, we will describe the conditions that the optical system L0 of each embodiment should preferably satisfy.

[0028] When the maximum image height of the optical system L0 is ImgH and the total optical length is L, it is preferable that the following condition (2) is satisfied. 0.40 <ImgH / L (2)

[0029] Conditional equation (2) specifies the ratio of the maximum image height to the total optical length of the optical system L0. Here, the maximum image height of the optical system L0 refers to the distance from the position on the optical axis where the peripheral light intensity is 10% when the position on the optical axis is defined as having 100% light intensity, to the optical axis. The total optical length L of the optical system L0 refers to the distance on the optical axis from the vertex of the object-side lens surface of the first lens G1, which is positioned closest to the object in the front group L1, to the image plane. If the ratio falls below the lower limit of conditional equation (2), the total length of the optical system L0 becomes long, which is undesirable because it makes the optical system larger. Furthermore, in order to ensure a sufficient total optical length for good correction of various aberrations, it is preferable to set the upper limit of conditional equation (2) to one of 3.00, 2.95, 2.90, 2.85, 2.80, 2.75, 2.70, 2.65, 2.60, 2.55, or 2.50. Furthermore, it is more preferable to set the upper limit of condition (2) to one of the following: 2.45, 2.40, 2.35, 2.30, 2.25, 2.20, 2.15, 2.10, 2.05, or 2.00.

[0030] When the focal length of the first lens G1, which is positioned closest to the object in the optical system L0, is fG1, it is preferable that the following condition (3) is satisfied. 0.52 <fG1 / f1 (3)

[0031] Conditional equation (3) specifies the focal length of the front group L1 and the focal length of the first lens G1, which is positioned closest to the object in the front group L1. Below the lower limit of conditional equation (3) is undesirable because it causes strong barrel distortion. Furthermore, in order to correct the distortion well, it is more preferable to set the upper limit of conditional equation (3) to one of 2.00, 1.95, 1.90, 1.85, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, or 1.50.

[0032] When the off-axis focal length in the meridional direction of the front group L1 is fω1, it is preferable that the following condition (4) is satisfied. -3.00 <fω1 / |f1|<0.00 (4)

[0033] Conditional equation (4) specifies the ratio of the on-axis focal length to the off-axis focal length of the front group L1. If it falls below the lower limit of conditional equation (4), the off-axis power of the front group L1 becomes weaker with respect to the paraxial axis, resulting in strong barrel distortion and field curvature, which is undesirable. If it exceeds the upper limit of conditional equation (4), the off-axis focal length of the front group L1 has a positive refractive power, making it difficult to shorten the overall length of the optical system L0, which is also undesirable.

[0034] When the focal length of the lens GR, which is positioned closest to the image in the rear group L2, is fGR, and the focal length of the rear group L2 is f2, it is preferable that the following condition (5) is satisfied. -6.00 <fGR / f2<-2.00 (5)

[0035] Condition (5) specifies the preferred range of focal length for lens GR, which is positioned closest to the image in the optical system L0. If the focal length falls below the lower limit of condition (5), the negative refractive power of lens GR relative to the rear group L2 becomes too weak. This is undesirable because it increases the back focus of optical system L0 and lengthens the overall length of optical system L0. If the focal length exceeds the upper limit of condition (5), the negative refractive power of lens GR relative to the rear group L2 becomes too strong. This is undesirable because it shortens the back focus of optical system L0 and brings the image plane IP and lens GR too close together.

[0036] When the half-angle of view of the optical system L0 is ω, it is preferable that the following condition (6) is satisfied. 48.0 < ω < 70.0 (6)

[0037] Conditional equation (6) specifies the preferred range of half-angle of view in the optical system L0. Below the lower limit of conditional equation (6) is undesirable because it results in overcorrection of distortion and field curvature. Above the upper limit of conditional equation (6) is also undesirable because it results in strong barrel distortion and field curvature.

[0038] When the Abbe number of the material of the negative lens GN1, which is positioned closest to the object in the rear group L2, is νd, it is preferable that the following condition (7) is satisfied. 14.0 < νd < 40.0 (7)

[0039] Conditional equation (7) specifies the preferred range of Abbe numbers for the negative lens GN1 material. If the Abbe number falls below the lower limit of conditional equation (7), it results in excessive correction for axial chromatic aberration, which is undesirable. If the Abbe number falls above the upper limit of conditional equation (7), it results in insufficient correction for axial chromatic aberration, which is also undesirable.

[0040] Furthermore, when the refractive index of the negative lens GN1 material with respect to the d line is nd, it is preferable that the following condition (8) is satisfied. 1.50 <nd<1.70 (8)

[0041] Conditional equation (8) specifies the preferred range of refractive index for the material of the negative lens GN1. If the refractive index falls below the lower limit of conditional equation (8), it will result in insufficient correction for spherical aberration, which is undesirable. If the refractive index exceeds the upper limit of conditional equation (8), it will result in excessive correction for spherical aberration, which is also undesirable.

[0042] Furthermore, it is more preferable to use the following conditional expressions (3a) to (8a) for the numerical ranges of conditional expressions (3) to (8). 0.41 <ImgH / L<1.50 (1a) 0.56 <fG1 / f1 (3a) -2.95 <fω1 / |f1|<-0.02 (4a) -5.80 <fGR / f2<-2.20 (5a) 49.0 < ω < 68.0 (6a) 20.0 < νd < 38.0 (7a) 1.52 <nd<1.65 (8a)

[0043] Furthermore, it is even more preferable to set the numerical range of conditional expressions (3) to (8) to the range of conditional expressions (3b) to (8b) below. 0.42 <ImgH / L<1.30 (1b) 0.60 <fG1 / f1 (3b) -2.90 <fω1 / |f1|<-0.05 (4b) -5.50 <fGR / f2<-2.80 (5b) 50.0 < ω < 65.0 (6b) 25.0 < νd < 35.0 (7a) 1.55 <nd<1.63 (8a)

[0044] Next, we will describe the preferred configurations that the optical system L0 of each embodiment should satisfy.

[0045] The optical system L0 of each embodiment preferably has at least 10 lenses. By distributing the refractive power among the lenses, the sensitivity of each lens can be reduced.

[0046] In the optical system L0 of each embodiment, it is preferable that the front group L1 includes at least three lenses. This allows for sufficient number of lenses to widen the optical system while effectively correcting distortion in the front group L1.

[0047] In the optical system L0 of each embodiment, it is preferable that the front group L1 includes a positive lens. Since the rear group L2 as a whole has a positive refractive power, by placing a positive lens in the front group L1, lenses with positive refractive power are placed on both the object side and the image side of the aperture diaphragm SP, respectively, so that field curvature and distortion aberrations can be corrected well.

[0048] In each embodiment, it is preferable that at least one of the object-side lens surface and the image-side lens surface of at least one lens included in the optical system L0 is aspherical. In particular, making the lens surface of the lens G1 located closest to the object in the front group L1 aspherical is preferable because it reduces the incident angle of off-axis light rays incident on lens G1, which is advantageous for correcting distortion and ensuring sufficient peripheral light. Furthermore, to enhance the above-mentioned effects, it is even more preferable that both the object-side lens surface and the image-side lens surface of lens G1 are aspherical.

[0049] In the optical system L0 of each embodiment, it is preferable that the rear group L2 has a positive lens, a positive lens, and a negative lens arranged in order from the object side. By arranging the positive lens near the image side of the aperture diaphragm SP, the light rays incident on the rear group L2 are converged, and the distance from the aperture diaphragm SP to the image plane can be shortened.

[0050] In each embodiment, among the lenses included in the optical system L0, it is preferable that the object-side lens surface of the lens GR, which is positioned closest to the image, is convex towards the object near the optical axis and concave towards the object at its periphery. Similarly, it is preferable that the image-side lens surface of lens GR is concave towards the image near the optical axis and convex towards the image at its periphery. This allows for correction of Petzval sum near the optical axis of lens GR while correcting astigmatism at its periphery.

[0051] Furthermore, it is preferable to use lenses made of resin material as the lenses included in the optical system L0, as this makes it possible to realize an aspherical lens shape with the inflection point described above.

[0052] Next, we will describe the detailed configurations of Examples 1 to 4. Note that for the optical system L0 of each example, we will omit the explanation of configurations similar to the optical system L0 of Example 1, and will mainly describe the differences from Example 1.

[0053] [Examples 1 to 3] The optical system L0 of Examples 1 to 3 consists of a front group L1 with negative refractive power, an aperture diaphragm SP, and a rear group L2 with positive refractive power, in that order from the object side. Because the front group L1 has negative refractive power, the optical system L0 has a so-called retrofocus type configuration, so the principal point is located on the image side, and the optical system L0 can be miniaturized in the radial direction while ensuring back focus.

[0054] In the optical system L0 of Examples 1 to 3, the front group L1 consists of G1 to G3 lenses, and the rear group L2 consists of G4 to G10 lenses. An optical filter FL is also placed on the image side of the rear group L2.

[0055] In the optical system L0 of Examples 1 to 3, both the object-side lens surface and the image-side lens surface of the lens G1, which is positioned closest to the object in the front group L1, have an aspherical shape. This reduces the incident angle of off-axis light rays incident on lens G1, which is advantageous for correcting distortion and ensuring sufficient peripheral illumination.

[0056] In the optical system L0 of Examples 1 to 3, the rear lens group L2 has positive lenses, positive lenses, and negative lenses arranged in order from the object side. As a result, there is a positive refractive power near the image side of the aperture diaphragm SP, which converges the light rays incident on the rear lens group L2 and shortens the distance from the aperture diaphragm SP to the image plane.

[0057] In the optical system L0 of Examples 1 to 3, the front group L1 includes a positive lens G3. As a result, lenses with positive refractive power are positioned on both the object side and the image side of the aperture diaphragm SP, thereby effectively correcting field curvature and distortion.

[0058] In the optical system L0 of Examples 1 to 3, the object-side lens surface of lens GR, which is positioned furthest towards the image in the rear group L2, is convex towards the object near the optical axis and concave towards the object in the peripheral area. Similarly, the image-side lens surface of lens GR is concave towards the image near the optical axis and convex towards the image in the peripheral area. This allows for correction of Petzval sum near the optical axis of lens GR while correcting astigmatism in the peripheral area. Furthermore, lens GR1, which is positioned adjacent to lens GR on the object side, and negative lens GN1, which is positioned furthest towards the object among the negative lenses included in the rear group L2, also have the same lens shape as lens GR.

[0059] In the optical system L0 of Examples 1 to 3, the negative lens GN1 located closest to the object in the rear group L2 is a lens made of resin material. This improves the moldability of the negative lens GN1 and makes it possible to realize an aspherical lens shape with an inflection point in the negative lens GN1.

[0060] [Example 4] In the optical system L0 of Example 4, the front group L1 consists of four lenses, G1 to G4, and the rear group L2 consists of seven lenses, G5 to G11. An optical filter FL is also positioned on the image side of the rear group L2.

[0061] In the optical system L0 of Example 4, the front group L1 has three negative lenses arranged in order from the object side. In order to ensure sufficient back focus in a wide-angle optical system, a strong negative refractive force is required on the object side of the optical system. By distributing this negative refractive force among three negative lenses, the refractive force per negative lens can be reduced, thereby suppressing barrel distortion and field curvature.

[0062] Next, the numerical examples corresponding to Examples 1 to 4 are shown below.

[0063] In the surface data for each numerical example, r(mm) represents the radius of curvature of each optical surface, and d(mm) represents the distance on the optical axis between the k-th surface and the (k+1)-th surface. Here, k is the surface number counted from the object side. Also, nd represents the refractive index of the material of each optical component with respect to the d line, and νd represents the Abbe number of the material of each optical component. Here, the Abbe number νd is given by the refractive index of the Fraunhofer lines c-line (656.3 nm), d-line (587.56 nm), and F-line (486.1 nm), respectively, where nC, nd, and nF are the refractive indices. νd=(nd-1) / (nF-nC) It is represented as follows.

[0064] In each numerical example, the half-angle of view (°) of the optical system L0 is shown, and the maximum image height corresponding to that half-angle of view is shown as "image height". Furthermore, in each numerical example, the focal length of each lens group at the d line is shown as lens group data. Note that d, focal length (mm), F number, and half-angle of view (°) are the values ​​when the optical system L0 of each example is focused at infinity. BF (back focus) represents the distance along the optical axis from the final lens surface (the surface closest to the image) to the paraxial image plane, converted to air equivalent. The total lens length is the sum of the distance along the optical axis from the object-side lens surface of the lens placed closest to the object among the lenses included in the optical system L0 to the image-side lens surface of the lens placed closest to the image, and the back focus.

[0065] Furthermore, for each lens, if the lens surface is aspherical, the symbol * is added to the right of the surface number. The aspherical shape is defined as follows, where X is the displacement from the surface vertex in the optical axis direction, h is the height from the optical axis perpendicular to the optical axis, R is the paraaxial radius of curvature, k is the cone constant, and A4, A6, A8, A10, A12, A14, A16, A18, and A20 are the aspherical coefficients of their respective orders. X=( h 2 / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 ]+A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 +A14×h14 +A16×h 16 +A18×h 18 +A20×h 20 It is represented by. In each aspherical coefficient, "e±XX" means "×10± XX ".

[0066] [Numerical Example 1] Unit: mm Surface data​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​20* 9.650 0.71 1.70500 14.0 6.30 21* 3.941 0.38 7.10 22 ∞ 0.26 1.51700 64.2 7.72 23 ∞ (variable) 7.81 Image plane ∞ Aspherical data Front page K = 0.00000e+00 A 4=-6.22726e-03 A 6= 2.49307e-03 A 8=-3.64351e-04 A10= 3.52612e-05 A12=-1.60799e-06 2nd side K = 0.00000e+00 A 4=-6.31637e-03 A 6=-7.54161e-03 A 8= 4.00579e-03 A10=-1.04685e-03 3rd page K = 0.00000e+00 A 4= 3.88578e-02 A 6=-2.24306e-02 A 8= 6.14943e-03 A10=-1.93389e-03 A12= 1.03603e-04 Side 4 K = 0.00000e+00 A 4= 4.75101e-02 A 6=-4.04733e-02 A 8=-9.32003e-03 A10=-1.56527e-03 5th page K = 0.00000e+00 A 4= 6.04506e-02 A 6= 1.06399e-02 Side 6 K = 0.00000e+00 A 4= 9.61786e-02 A 6= 2.13213e-01 A 8=-4.47519e-01 A10= 4.46135e-01 A18=-5.15324e-01 A20= 1.37029e-01 Side 8 K = 0.00000e+00 A 4=-9.37315e-02 A 6=-1.20621e-01 Page 9 K = 0.00000e+00 A 4= 1.21352e-01 A 6=-3.85874e-01 A 8=-7.05670e-01 A10= 6.83274e+00 A12=-2.23937e+01 A14= 4.22889e+01 A16=-4.74471e+01 A18= 2.95638e+01 A20=-7.91667e+00 Page 10 K = 0.00000e+00 A 4= 2.84988e-01 A 6=-5.32788e-01 A 8= 2.28548e-01 A10= 2.74332e+00 A12=-1.07381e+01 A14= 2.03426e+01 A16=-2.15153e+01 A18= 1.20411e+01 A20=-2.76919e+00 Page 11 K = 0.00000e+00 A 4=-3.24436e-02 A 6=-5.91821e-04 Page 12 K = 0.00000e+00 A 4=-3.47386e-01 A 6= 1.67850e-01 Page 13 K = 0.00000e+00 A 4=-2.73129e-01 A 6=-8.79136e-04 A 8= 4.79035e-01 A10=-1.38435e+00 A12= 2.28912e+00 A14=-2.33036e+00 A16= 1.44741e+00 A18=-5.04487e-01 A20= 7.62655e-02 Page 14 K = 8.11732e+00 A 4=-1.16111e-02 A 6=-9.04062e-02 A 8= 1.54999e-01 A10=-4.17454e-01 A12= 7.33737e-01 A14=-8.04871e-01 A16= 5.33042e-01 A18=-1.98497e-01 A20= 3.21986e-02 Page 15 K =-1.00000e+00 A 4=-2.98752e-02 A 6= 1.36617e-02 A 8=-2.70764e-02 A10= 3.50423e-02 A12=-3.00282e-02 A14= 1.50734e-02 A16=-4.36035e-03 A18= 7.19102e-04 A20=-5.68105e-05 Page 16 K = 0.00000e+00 A 4= 5.76356e-02 A 6=-1.45974e-02 Page 17 K = 0.00000e+00 A 4= 6.65221e-02 A 6= 8.95717e-03 A 8=-6.67550e-03 A10= 7.80982e-04 Page 18 K = 0.00000e+00 A 4=-5.00789e-02 A 6= 3.86987e-03 A 8=-3.64654e-04 Page 19 K = 0.00000e+00 A 4=-4.49372e-02 A 6= 2.22702e-03 A 8=-1.30128e-04 A10= 4.81439e-05 A12=-6.92656e-06 Page 20 K = 0.00000e+00 A 4=-1.12949e-02 A 6=-3.05329e-03 A 8= 1.35380e-03 A10=-1.91853e-04 A12= 1.10320e-05 A14=-2.75407e-07 A16= 6.58006e-09 Page 21 K = 0.00000e+00 A 4=-3.51306e-02 A 6= 5.10806e-03 A 8=-5.06655e-04 A10= 2.25555e-05 A12=-2.41588e-07 A14=-8.18507e-10 A16=-6.12513e-10 Various data Focal length 3.05 F-number 2.21 Half-angle 51.80 Image height 3.88 Lens length 9.00 BF 0.56 Lens group data Group starting plane focal length L1 1 -7.27 L2 7 2.52 Single lens data Lens starting plane, focal length G1 1 -7.30 G2 3 -10.73 G3 5 8.54 G4 8 6.79 G5 11 3.34 G6 13 -5.06 G7 15 -33.42 G8 17 5.10 G9 19 32.59 G10 21 -9.96

[0067] [Numerical Example 2] Unit: mm Surface data Face number rd nd νd Effective diameter 1* 7.603 0.50 1.54400 56.0 5.65 2* 2.188 0.26 4.06 3* 2.277 0.57 1.69800 16.3 3.61 4* 1.580 0.51 2.80 5* 1.919 0.39 1.62100 23.6 2.10 6* 2.936 (variable) 1.62 7 (aperture) ∞ 0.10 1.38 8* -5.004 0.34 1.59100 27.2 1.38 9* -2.364 -0.04 1.52 10* -58.417 0.82 1.54400 56.0 1.68 11* -1.567 0.10 2.03 12* -6.235 0.33 1.59100 27.2 2.11 13* 5.581 0.37 2.43 14* -4.238 0.34 1.69800 16.3 2.51 15* -6.006 0.12 3.22 16* -12.367 0.72 1.54400 56.0 3.86 17* -2.300 0.12 4.34 18* 2.752 0.87 1.54400 56.0 5.10 19* 2.968 0.24 5.83 20* 8.650 0.71 1.70500 14.0 6.41 21* 3.917 0.38 7.13 22 ∞ 0.26 1.51700 64.2 7.61 23 ∞ (variable) 7.75 Image plane ∞ Aspherical data Front page K = 0.00000e+00 A 4=-2.54223e-03 A 6= 2.33757e-03 A 8=-3.84207e-04 A10= 3.50458e-05 A12=-1.32461e-06 Page 2 K = 0.00000e+00 A 4= 7.40521e-03 A 6=-1.41320e-02 A 8= 5.86577e-03 A10=-1.03139e-03 Page 3 K = 0.00000e+00 A 4= 4.76308e-02 A 6=-2.67859e-02 A 8= 8.78811e-03 A10=-2.38026e-03 A12= 1.84157e-04 Page 4 K = 0.00000e+00 A 4= 4.32085e-02 A 6=-3.07918e-02 A 8=-9.48084e-03 A10=-6.03052e-05 Page 5 K = 0.00000e+00 A 4= 2.86233e-02 A 6= 8.52926e-03 Page 6 K = 0.00000e+00 A 4= 7.74792e-02 A 6= 1.75679e-01 A 8=-3.64574e-01 A10= 3.79370e-01 A18=-5.15324e-01 A20= 1.37029e-01 Page 8 K = 0.00000e+00 A 4=-8.87681e-02 A 6=-1.18145e-01 Page 9 K = 0.00000e+00 A 4= 1.15568e-01 A 6=-3.86521e-01 A 8=-6.98859e-01 A10= 6.69233e+00 A12=-2.19911e+01 A14= 4.18834e+01 A16=-4.75786e+01 A18= 3.01112e+01 A20=-8.20593e+00 Page 10 K = 0.00000e+00 A 4= 2.75007e-01 A 6=-5.19088e-01 A 8= 1.94907e-01 A10= 2.85683e+00 A12=-1.09850e+01 A14= 2.08839e+01 A16=-2.24096e+01 A18= 1.27730e+01 A20=-2.98287e+00 Page 11 K = 0.00000e+00 A 4=-2.23791e-02 A 6=-1.40848e-03 Page 12 K = 0.00000e+00 A 4=-3.62312e-01 A 6= 1.56113e-01 Page 13 K = 0.00000e+00 A 4=-2.91008e-01 A 6= 4.72921e-03 A 8= 4.75371e-01 A10=-1.37581e+00 A12= 2.28965e+00 A14=-2.34641e+00 A16= 1.46350e+00 A18=-5.11400e-01 A20= 7.74838e-02 Page 14 K = 6.24444e+00 A 4=-6.07468e-03 A 6=-9.27356e-02 A 8= 1.54356e-01 A10=-4.04410e-01 A12= 7.11676e-01 A14=-7.80211e-01 A16= 5.15461e-01 A18=-1.93139e-01 A20= 3.16383e-02 Page 15 K =-1.00000e+00 A 4=-3.26227e-02 A 6= 1.45332e-02 A 8=-2.15837e-02 A10= 3.18867e-02 A12=-3.00215e-02 A14= 1.50493e-02 A16=-4.14077e-03 A18= 6.42277e-04 A20=-5.08179e-05 Page 16 K = 0.00000e+00 A 4= 5.95171e-02 A 6=-1.53097e-02 Page 17 K = 0.00000e+00 A 4= 6.83654e-02 A 6= 1.07515e-02 A 8=-7.32994e-03 A10= 8.46131e-04 Page 18 K = 0.00000e+00 A 4=-5.61689e-02 A 6= 5.80887e-03 A 8=-5.52956e-04 Page 19 K = 0.00000e+00 A 4=-4.68548e-02 A 6= 3.40289e-03 A 8=-2.48175e-04 A10= 3.88490e-05 A12=-4.96182e-06 Page 20 K = 0.00000e+00 A 4=-1.15333e-02 A 6=-3.03950e-03 A 8= 1.49966e-03 A10=-2.38658e-04 A12= 1.75214e-05 A14=-6.47029e-07 A16= 1.24837e-08 Page 21 K = 0.00000e+00 A 4=-3.51270e-02 A 6= 5.29599e-03 A 8=-5.16142e-04 A10= 1.99812e-05 A12= 3.46321e-08 A14=-1.78986e-09 A16=-1.05303e-09 Various data Focal length 2.69 F-number 2.21 Half-angle 55.27 Image height 3.88 Lens length: 8.83 BF 0.45 Lens group data Group starting plane focal length L1 1 -6.30 L2 7 2.40 Single lens data Lens starting plane, focal length G1 1 -5.84 G2 3 -11.14 G3 5 7.77 G4 8 7.24 G5 11 2.95 G6 13 -4.93 G7 15 -22.40 G8 17 5.06 G9 19 28.66 G10 21 -10.82

[0068] [Numerical Example 3] Unit: mm Surface data Face number rd nd νd Effective diameter 1* 4.052 0.50 1.54400 56.0 4.97 2* 2.130 0.12 3.95 3* 2.256 0.40 1.69800 16.3 3.64 4* 1.715 0.73 3.03 5* 1.915 0.33 1.62100 23.6 1.97 6* 2.290 (variable) 1.54 7 (aperture) ∞ 0.10 1.42 8* -8.985 0.32 1.59100 27.2 1.42 9* -3.828 0.13 1.54 10* 126.934 0.85 1.54400 56.0 1.61 11* -1.576 0.10 2.05 12* -13.008 0.30 1.59100 27.2 2.17 13* 3.580 0.30 2.48 14* -4.280 0.30 1.69800 16.3 2.55 15* -5.779 0.24 3.10 16* -17.744 0.63 1.54400 56.0 4.01 17* -2.291 0.10 4.34 18* 2.732 0.87 1.54400 56.0 4.99 19* 3.042 0.35 5.93 20* 14.123 0.71 1.70500 14.0 6.84 21* 3.877 0.38 7.50 22 ∞ 0.26 1.51700 64.2 7.61 23 ∞ (variable) 7.75 Image plane ∞ Aspherical data Front page K = 0.00000e+00 A 4=-3.07731e-03 A 6= 3.00737e-03 A 8=-8.47144e-04 A10= 1.21092e-04 A12=-6.93945e-06 2nd side K = 0.00000e+00 A 4= 2.86153e-02 A 6=-3.02061e-02 A 8= 9.25596e-03 A10=-1.37869e-03 Page 3 K = 0.00000e+00 A 4= 6.15659e-02 A 6=-4.70842e-02 A 8= 1.50910e-02 A10=-2.32884e-03 A12= 2.32308e-05 Page 4 K = 0.00000e+00 A 4= 3.86307e-02 A 6=-4.60362e-02 A 8= 1.68308e-02 A10=-4.98505e-03 Page 5 K = 0.00000e+00 A 4= 3.66836e-02 A 6= 2.61744e-02 Page 6 K = 0.00000e+00 A 4= 8.63360e-02 A 6= 1.36372e-01 A 8=-2.19196e-01 A10= 2.29418e-01 A18=-5.15324e-01 A20= 1.37029e-01 Page 8 K = 0.00000e+00 A 4=-1.03223e-01 A 6=-9.83741e-02 Page 9 K = 0.00000e+00 A 4=-3.64040e-02 A 6=-1.43447e-01 A 8=-5.71314e-01 A10= 5.77888e+00 A12=-2.47397e+01 A14= 6.16318e+01 A16=-9.00846e+01 A18= 7.18831e+01 A20=-2.41209e+01 Page 10 K = 0.00000e+00 A 4= 1.11675e-01 A 6=-1.51230e-01 A 8=-3.40553e-01 A10= 3.41133e+00 A12=-1.18030e+01 A14= 2.25319e+01 A16=-2.45121e+01 A18= 1.40973e+01 A20=-3.29067e+00 Page 11 K = 0.00000e+00 A 4= 3.16674e-02 A 6=-3.34507e-02 Page 12 K = 0.00000e+00 A 4=-3.06293e-01 A 6= 1.14326e-01 Page 13 K = 0.00000e+00 A 4=-2.82012e-01 A 6=-2.15392e-02 A 8= 4.70890e-01 A10=-1.36401e+00 A12= 2.26373e+00 A14=-2.28280e+00 A16= 1.39120e+00 A18=-4.73228e-01 A20= 6.95500e-02 Page 14 K =-6.52180e+00 A 4= 1.60212e-02 A 6=-1.14233e-01 A 8= 1.34753e-01 A10=-3.61854e-01 A12= 6.51815e-01 A14=-7.07864e-01 A16= 4.64806e-01 A18=-1.75866e-01 A20= 2.96999e-02 Page 15 K =-1.00000e+00 A 4=-2.27112e-02 A 6= 1.02657e-02 A 8=-2.01315e-02 A10= 3.22438e-02 A12=-3.06026e-02 A14= 1.42662e-02 A16=-3.20216e-03 A18=3.04576e-04 A20=-5.54668e-06 Page 16 K = 0.00000e+00 A 4= 6.26857e-02 A 6=-1.40260e-02 Page 17 K = 0.00000e+00 A 4= 6.95417e-02 A 6= 1.29310e-02 A 8=-8.04863e-03 A10= 9.39637e-04 Side 18 K = 0.00000e+00 A 4=-5.92072e-02 A 6= 4.64173e-03 A 8=-3.64040e-04 Page 19 K = 0.00000e+00 A 4=-3.98586e-02 A 6= 3.65251e-03 A 8=-4.07558e-04 A10= 3.33785e-05 A12=-2.86780e-06 Page 20 K = 0.00000e+00 A 4=-4.90605e-03 A 6=-4.51089e-03 A 8= 1.75998e-03 A10=-2.96272e-04 A12= 2.67864e-05 A14=-1.26658e-06 A16= 2.47217e-08 Page 21 K = 0.00000e+00 A 4=-3.29180e-02 A 6= 4.26108e-03 A 8=-3.93460e-04 A10= 1.76042e-05 A12=-6.00855e-08 A14=-3.39119e-09 A16=-9.90108e-10 Various data Focal length 3.02 F-number 2.21 Half-angle 52.06 Image height 3.88 Lens length 8.70 BF 0.45 Lens group data Group starting plane focal length L1 1 -8.21 L2 7 2.53 Single lens data Lens starting plane, focal length G1 1 -9.08 G2 3 -14.67 G3 5 14.10 G4 8 11.03 G5 10 2.87 G6 12 -4.72 G7 14 -25.75 G8 16 4.77 G9 18 24.73 G10 20 -7.80

[0069] [Numerical Example 4] Unit: mm Surface data Face number rd nd νd Effective diameter 1* 5.000 0.50 1.54400 56.0 5.88 2* 2.227 0.34 4.24 3* 2.344 0.40 1.69800 16.3 3.76 4* 1.793 0.47 3.29 5* 6.487 0.30 1.54400 56.0 3.07 6* 4.232 0.19 2.76 7* 1.969 0.30 1.62100 23.6 2.09 8* 2.592 (variable) 1.75 9 (aperture) ∞ 0.10 1.46 10* -5.665 0.30 1.59100 27.2 1.35 11* -2.538 0.08 1.47 12* 89.117 0.83 1.54400 56.0 1.56 13* -1.557 0.10 1.93 14* -3.735 0.30 1.59100 27.2 1.97 15* 6.169 0.34 2.34 16* -5.072 0.35 1.69800 16.3 2.43 17* -8.148 0.10 3.12 18* 27.830 0.72 1.54400 56.0 4.01 19* -2.347 0.16 4.39 20* 2.820 0.87 1.54400 56.0 5.22 21* 2.961 0.24 5.82 22* 8.518 0.71 1.70500 14.0 6.28 23* 4.126 0.38 7.13 24 ∞ 0.26 1.51700 64.2 7.32 25 ∞ (variable) 7.43 Image plane ∞ Aspherical data Front page K = 0.00000e+00 A 4=-6.07893e-04 A 6= 1.32175e-03 A 8=-2.93328e-04 A10= 3.07045e-05 A12=-1.25878e-06 2nd side K = 0.00000e+00 A 4= 3.03485e-02 A 6=-1.67125e-02 A 8= 6.33996e-03 A10=-1.07597e-03 3rd page K = 0.00000e+00 A 4= 9.16094e-02 A 6=-3.58801e-02 A 8= 1.03115e-02 A10=-2.84761e-03 A12= 2.39186e-04 Side 4 K = 0.00000e+00 A 4= 9.51787e-02 A 6=-2.90906e-02 A 8=-9.16503e-03 A10= 1.21401e-03 Page 5 K = 0.00000e+00 A 4= 1.12544e-01 A 6=-2.08590e-02 A 8= 8.45431e-04 A10=-5.73030e-04 Page 6 K = 0.00000e+00 A 4= 1.55899e-01 A 6=-5.98208e-02 Page 7 K = 0.00000e+00 A 4= 6.97646e-02 A 6=-3.75828e-02 Page 8 K = 0.00000e+00 A 4= 5.97916e-02 A 6= 2.65502e-01 A 8=-6.09114e-01 A10= 5.87441e-01 A18=-5.15324e-01 A20= 1.37029e-01 Page 10 K = 0.00000e+00 A 4=-8.55150e-02 A 6=-1.28438e-01 Page 11 K = 0.00000e+00 A 4= 1.59565e-01 A 6=-6.60450e-01 A 8= 7.69393e-01 A10=-3.08663e-01 A12= 8.56686e-02 A14=-3.97626e+00 A16= 1.40912e+01 A18=-1.89261e+01 A20= 9.22077e+00 Page 12 K = 0.00000e+00 A 4= 3.35567e-01 A 6=-6.23402e-01 A 8= 3.12741e-01 A10= 2.85469e+00 A12=-1.11485e+01 A14= 2.10627e+01 A16=-2.22059e+01 A18= 1.20228e+01 A20=-2.44933e+00 Page 13 K = 0.00000e+00 A 4= 1.44043e-02 A 6=-3.33594e-02 Page 14 K = 0.00000e+00 A 4=-4.07482e-01 A 6= 1.58953e-01 Page 15 K = 0.00000e+00 A 4=-3.34168e-01 A 6= 6.35319e-03 A 8= 5.01334e-01 A10=-1.43512e+00 A12= 2.41307e+00 A14=-2.48412e+00 A16= 1.54198e+00 A18=-5.33067e-01 A20= 7.98230e-02 Page 16 K =-1.26320e+01 A 4= 1.85302e-02 A 6=-1.69465e-01 A 8= 1.85576e-01 A10=-3.88721e-01 A12= 6.94163e-01 A14=-7.92491e-01 A16= 5.32772e-01 A18=-1.98749e-01 A20= 3.05655e-02 Page 17 K =-1.00000e+00 A 4=-1.50198e-02 A 6=-5.99313e-03 A 8=-1.78373e-02 A10= 3.19572e-02 A12=-3.04820e-02 A14= 1.52540e-02 A16=-4.63191e-03 A18=9.11564e-04 A20=-9.37171e-05 Side 18 K = 0.00000e+00 A 4= 4.50798e-02 A 6=-1.13848e-02 Page 19 K = 0.00000e+00 A 4= 6.75442e-02 A 6= 1.15663e-02 A 8=-7.29456e-03 A10= 8.55124e-04 Page 20 K = 0.00000e+00 A 4=-6.04143e-02 A 6= 7.15022e-03 A 8=-5.74141e-04 Page 21 K = 0.00000e+00 A 4=-5.00251e-02 A 6= 4.21282e-03 A 8=-3.31094e-04 A10= 5.54193e-05 A12=-6.88983e-06 Page 22 K = 0.00000e+00 A 4=-1.08354e-02 A 6=-3.65405e-03 A 8= 1.55345e-03 A10=-2.31254e-04 A12= 1.62608e-05 A14=-5.90919e-07 A16= 1.15953e-08 Page 23 K = 0.00000e+00 A 4=-3.19763e-02 A 6= 4.61814e-03 A 8=-4.53528e-04 A10= 1.92003e-05 A12= 1.72738e-08 A14= 4.58410e-10 A16=-1.34101e-09 Various data Focal length 2.58 F-number 2.21 Half-angle 56.35 Image height 3.88 Lens length 9.00 BF 0.45 Lens group data Group starting plane focal length L1 1 -6.13 L2 9 2.36 Single lens data Lens starting plane, focal length G1 1 -7.88 G2 3 -15.55 G3 5 -23.47 G4 7 11.15 G5 10 7.51 G6 12 2.82 G7 14 -3.89 G8 16 -20.19 G9 18 4.01 G10 20 34.20 G11 22 -12.16

[0070] The numerical values ​​for conditional formulas (1) to (8) in each embodiment are shown in Table 1.

[0071] [Table 1]

[0072] [Imaging device] Next, we will describe an imaging device that uses the optical system L0 of each embodiment as the imaging optical system.

[0073] Figure 10 is a schematic diagram of an imaging device 10 equipped with the optical system L0 of each embodiment. The imaging device 10 comprises a camera body 13, an optical system 11 which is the same as any of the optical systems L0 described in Embodiments 1 to 4 above, and a light-receiving element 12 which converts the image formed by the optical system 11 into photoelectricity.

[0074] Furthermore, an image sensor such as a CCD or CMOS sensor can be used as the light-receiving element 12. In this case, the output image can be made higher quality by correcting various aberrations such as distortion and chromatic aberration of the image acquired by the light-receiving element 12, for example, using an electrical method.

[0075] Furthermore, the optical system L0 in each embodiment is not limited to the digital still camera shown in Figure 10, but can be applied to various optical devices such as digital video cameras and silver halide film cameras. Also, the camera can be either a fixed-lens type or a lens-interchangeable type.

[0076] [Lens device] Next, we will describe the lens apparatus using the optical system L0 of each embodiment.

[0077] Figure 11 is a schematic diagram of the external appearance of a lens device 20 equipped with the optical system L0 of each embodiment. The lens device 20 is a so-called interchangeable lens that is detachably attached to a camera body (not shown). The lens device 20 has a photographic optical system 21 composed of one of the optical systems described in Embodiments 1 to 4. The lens device 20 also has a focus operation means 22 and an operation means 23 for changing the shooting mode.

[0078] By operating the focus control means 22, the arrangement of the imaging optical system 21 can be changed mechanically or electrically, thereby changing the focal position.

[0079] Furthermore, the user may operate the operating means 23 to change the arrangement of the lens group of the imaging optical system 21 for purposes other than focusing. For example, the arrangement of the lens group of the imaging optical system 21 may be changed mechanically or electrically in conjunction with the operation of the operating means 23, thereby changing the aberration of the imaging optical system 21. In this case, it is preferable that the focus position does not change substantially.

[0080] Although preferred embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of its gist.

[0081] Furthermore, the disclosures herein include the following configurations.

[0082] (Composition 1) An optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, The optical system has at least 10 lenses, The aforementioned group includes an aspherical lens having an inflection point. When the focal length of the entire optical system is f, the focal length of the front group is f1, the maximum image height of the optical system is ImgH, and the total optical length of the optical system is L, -2.98 <f1 / f<0.00 0.40 <ImgH / L An optical system characterized by satisfying the following conditional equation.

[0083] (Configuration 2) An optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, The optical system has an aspherical lens with an inflection point, The aforementioned front group includes at least three lenses, When the focal length of the entire optical system is f and the focal length of the front group is f1, -2.98 <f1 / f<0.00 An optical system characterized by satisfying the following conditional equation.

[0084] (Composition 3) When fG1 is the focal length of lens G1, which is positioned closest to the object among the lenses included in the front group, 0.52 <fG1 / f1 The optical system according to configuration 1 or 2, characterized by satisfying the following conditional expression.

[0085] (Configuration 4) The front group includes a positive lens, and the optical system according to any one of Configurations 1 to 3, characterized in that

[0086] (Configuration 5) In the rear group, a positive lens, a positive lens, and a negative lens are arranged in this order from the object side to the image side, and the optical system according to any one of Configurations 1 to 4, characterized in that

[0087] (Configuration 6) When the off-axis focal length in the meridional direction of the front group is fω1, -3.00 < fω1 / |f1| < 0.00 The optical system according to any one of Configurations 1 to 5, characterized in that it satisfies the conditional expression

[0088] (Configuration 7) When the focal length of the lens GR arranged closest to the image side in the rear group is fGR and the focal length of the rear group is f2, -6.00 < fGR / f2 < -2.00 The optical system according to any one of Configurations 1 to 6, characterized in that it satisfies the conditional expression

[0089] (Configuration 8) When the semi-field angle corresponding to the maximum image height is ω[°], 48.0 < ω < 70.0 The optical system according to any one of Configurations 1 to 7, characterized in that it satisfies the conditional expression

[0090] (Configuration 9) When the Abbe number of the material of the negative lens GN1 arranged closest to the object side among the negative lenses included in the rear group is νd, 14.0 < νd < 40.0 The optical system according to any one of Configurations 1 to 8, characterized in that it satisfies the conditional expression

[0091] (Configuration 10) When the refractive index of the material of the negative lens GN1 with respect to the d-line is nd, 1.50 < nd < 1.70 The optical system according to any one of Configurations 1 to 9, characterized by satisfying the conditional expression.

[0092] (Configuration 11) The optical system has a lens made of a resin material, The optical system according to any one of Configurations 1 to 10, characterized in that at least one of the object-side lens surface of the lens and the image-side lens is an aspherical surface.

[0093] (Configuration 12) The object-side lens surface of the lens GR, which is arranged most closely to the image side in the rear group, is convex on the object side near the optical axis and concave on the object side at the peripheral part, The image-side lens surface of the lens GR is concave on the image side near the optical axis and convex on the image side at the peripheral part, and the optical system according to any one of Configurations 1 to 11 is characterized by this.[[ID=N19]]

[0094] (Configuration 13) The object-side lens surface of the lens GR1, which is arranged adjacent to the object side of the lens arranged most closely to the image side in the rear group, is convex on the object side near the optical axis and concave on the object side at the peripheral part, The image-side lens surface of the lens GR1 is concave on the image side near the optical axis and convex on the image side at the peripheral part, and the optical system according to any one of Configurations 1 to 12 is characterized by this.

[0095] (Configuration 14)<s The object-side lens surface of the negative lens GN1, which is arranged most closely to the object side among the negative lenses included in the rear group, is convex on the object side near the optical axis and concave on the object side at the peripheral part, The image-side lens surface of the negative lens GN1 is concave on the image side near the optical axis and convex on the image side at the peripheral part, and the optical system according to any one of Configurations 1 to 13 is characterized by this.

[0096] (Configuration 15) The front group consists of three lenses, and the rear group consists of seven lenses, and the optical system according to any one of Configurations 1 to 14 is characterized by this.

[0097] (Composition 16) The optical system according to any one of configurations 1 to 14, characterized in that the front group consists of four lenses and the rear group consists of seven lenses.

[0098] (Composition 17) The optical system described in any one of configurations 1 to 16, An imaging device characterized by having an image sensor that receives light from an image formed by the optical system.

[0099] (Composition 18) A lens device characterized by having an optical system according to any one of configurations 1 to 16 and an operating means operated by a user. [Explanation of symbols]

[0100] L1 front group L2 rear group SP aperture diaphragm FL Optical Filter IP image plane

Claims

1. An optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, The optical system has at least 10 lenses, The aforementioned group includes an aspherical lens having an inflection point. When the focal length of the entire optical system is f, the focal length of the front group is f1, the maximum image height of the optical system is ImgH, and the total optical length of the optical system is L, -2.98<f1 / f<0.00 0.40<ImgH / L An optical system characterized by satisfying the following conditional equation.

2. When fG1 is the focal length of lens G1, which is positioned closest to the object among the lenses included in the front group, 0.52<fG1 / f1 The optical system according to claim 1, characterized in that it satisfies the following condition.

3. The optical system according to claim 1 or 2, characterized in that the front group includes a positive lens.

4. The optical system according to claim 1 or 2, characterized in that in the rear group, a positive lens, a positive lens, and a negative lens are arranged in order from the object side to the image side.

5. When the off-axis focal length in the meridional direction of the aforementioned front group is fω1, -3.00<fω1 / |f1|<0.00 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

6. When the focal length of lens GR, which is positioned closest to the image sensor in the rear group, is fGR, and the focal length of the rear group is f2, -6.00<fGR / f2<-2.00 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

7. When the half-angle of view corresponding to the maximum image height is ω [°] 48.0<ω<70.0 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

8. When the Abbe number of the material of the negative lens GN1, which is the negative lens located closest to the object among the negative lenses included in the aforementioned group, is νd, 14.0<νd<40.0 The optical system according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

9. When the refractive index of the material of the negative lens GN1 with respect to the d line is nd, 1.50<nd<1.70 The optical system according to claim 8, characterized in that it satisfies the following conditional expression.

10. The optical system has lenses made of resin material, The optical system according to claim 1 or 2, characterized in that at least one of the object-side lens surface and the image-side lens of the lens made of the resin material is aspherical.

11. The object-side lens surface of the lens GR, which is positioned closest to the image in the aforementioned rear group, is convex towards the object near the optical axis and concave towards the object at its periphery. The optical system according to claim 1 or 2, characterized in that the image-side lens surface of the lens GR is concave towards the image side near the optical axis and convex towards the image side at the periphery.

12. In the aforementioned rear group, the object-side lens surface of lens GR1, which is positioned adjacent to the object-side lens of the lens positioned closest to the image axis, is convex towards the object side near the optical axis and concave towards the object side at the periphery. The optical system according to claim 1 or 2, characterized in that the image-side lens surface of the lens GR1 is concave towards the image side near the optical axis and convex towards the image side at the periphery.

13. The object-side lens surface of the negative lens GN1, which is positioned closest to the object among the negative lenses included in the aforementioned rear group, is convex towards the object near the optical axis and concave towards the object at its periphery. The optical system according to claim 1 or 2, characterized in that the image-side lens surface of the negative lens GN1 is concave towards the image side near the optical axis and convex towards the image side at the periphery.

14. The optical system according to claim 1 or 2, characterized in that the front group consists of three lenses and the rear group consists of seven lenses.

15. The optical system according to claim 1 or 2, characterized in that the front group consists of four lenses and the rear group consists of seven lenses.

16. An optical system having a front group with negative refractive power, an aperture diaphragm, and a rear group with positive refractive power, arranged in order from the object side to the image side, The optical system has an aspherical lens with an inflection point, The aforementioned front group includes at least three lenses, When the focal length of the entire optical system is f and the focal length of the front group is f1, -2.98<f1 / f<0.00 An optical system characterized by satisfying the following conditional equation.

17. The optical system according to claim 1 or 2, An imaging device characterized by having an image sensor that receives light from an image formed by the optical system.

18. A lens device characterized by comprising an optical system according to claim 1 or 2 and an operating means operated by a user.

Images