Optical systems and optical equipment

Abstract

This invention provides an optical system, an optical device, and a method for manufacturing an optical system having a wide field of view and good optical performance. The optical system (OL) used in an optical device such as a camera (1) includes, from the object side, a first lens group (G1), an aperture stop (S), and a second lens group (G2). The first lens group (G1) includes, from the object side, at least two negative lenses (e.g., negative lenses (L1n1, L1n2)), a positive lens (e.g., positive lens (L1p1)), and a rear negative lens (e.g., negative lens (L1nr)), satisfying conditions based on a predetermined conditional expression.

Description

Technical Field

[0001] The invention relates to an optical system, an optical device and a method for manufacturing the optical system. Background Art

[0002] Conventionally, an optical system that realizes a wide angle of view has been disclosed (for example, see Patent Document 1). However, Patent Document 1 requires further improvement in optical performance.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 09-127412 Summary of the invention

[0006] The optical system of the first aspect of the present invention comprises, in order from the object side, a first lens group, an aperture stop, and a second lens group, wherein the first lens group comprises, in order from the object side, at least two negative lenses, a positive lens, and a rear negative lens, and satisfies the following conditions:

[0007] 90.00°<ωmax

[0008] in,

[0009] ωmax: Maximum value of the half field angle of the optical system [°].

[0010] The optical system of the second aspect of the present invention comprises, in order from the object side, a first lens group, an aperture stop, and a second lens group, wherein the first lens group comprises, in order from the object side, at least two negative lenses, a positive lens, and a rear negative lens, and satisfies the following conditions:

[0011] 0.300<(-f1) / θmax<9.200

[0012] in,

[0013] f1: focal length of the first lens group

[0014] θmax: The maximum value of the half field angle of the optical system [radians].

[0015] The optical system of the third aspect of the present invention comprises, in order from the object side, a first lens group, an aperture stop, and a second lens group, wherein the first lens group comprises, in order from the object side, at least two negative lenses, a positive lens, and a rear negative lens, and satisfies the following conditions:

[0016] 0.280 <D12 / (-f1)<1.200

[0017] in,

[0018] D12: The distance on the optical axis between the two negative lenses of the first lens group disposed closest to the object side

[0019] f1: focal length of the first lens group.

[0020] A method for manufacturing an optical system according to a first aspect of the present invention comprises a first lens group, an aperture stop, and a second lens group in order from the object side, wherein the method for manufacturing the optical system comprises the following steps: configuring at least two negative lenses, a positive lens, and a rear negative lens in the first lens group in order from the object side; and configuring the lenses in a manner that satisfies the following condition, namely,

[0021] 90.00°<ωmax

[0022] in,

[0023] ωmax: Maximum value of the half field angle of the optical system [°].

[0024] A second aspect of the present invention provides a method for manufacturing an optical system, wherein the optical system comprises a first lens group, an aperture stop, and a second lens group in order from the object side, wherein the method for manufacturing the optical system comprises the following steps: configuring at least two negative lenses, a positive lens, and a rear negative lens in the first lens group in order from the object side; and configuring the lenses in a manner that satisfies the following condition, namely,

[0025] 0.300<(-f1) / θmax<9.200

[0026] in,

[0027] f1: focal length of the first lens group

[0028] θmax: The maximum value of the half field angle of the optical system [radians].

[0029] The third aspect of the present invention is a method for manufacturing an optical system, wherein the optical system comprises a first lens group, an aperture stop, and a second lens group in order from the object side, wherein the method for manufacturing the optical system comprises the following steps: configuring at least two negative lenses, a positive lens, and a rear negative lens in the first lens group in order from the object side; and configuring the lenses in a manner that satisfies the following condition, namely,

[0030] 0.280 <D12 / (-f1)<1.200

[0031] in,

[0032] D12: The distance on the optical axis between the two negative lenses of the first lens group disposed closest to the object side

[0033] f1: focal length of the first lens group. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a cross-sectional view showing the lens structure of the optical system according to the first embodiment.

[0035] Figure 2 1 and 2 are diagrams showing various aberrations of the optical system of the first embodiment.

[0036] Figure 3 It is a cross-sectional view showing the lens structure of the optical system according to the second embodiment.

[0037] Figure 4 1 and 2 are diagrams showing various aberrations of the optical system of the second embodiment.

[0038] Figure 5 It is a cross-sectional view showing the lens structure of the optical system of the third embodiment.

[0039] Figure 6 These are various aberration diagrams of the optical system of the third embodiment.

[0040] Figure 7 It is a cross-sectional view showing the lens structure of the optical system of the fourth embodiment.

[0041] Figure 8 These are various aberration diagrams of the optical system of the fourth embodiment.

[0042] Fig. 9 It is a cross-sectional view showing the lens structure of the optical system of Example 5.

[0043] Fig.10 These are various aberration diagrams of the optical system of Example 5.

[0044] Fig.11 It is a cross-sectional view showing the lens structure of the optical system of Example 6.

[0045] Fig.12 These are various aberration diagrams of the optical system of Example 6.

[0046] Fig.13 It is a cross-sectional view showing the lens structure of the optical system of Example 7.

[0047] Fig.14 These are various aberration diagrams of the optical system of Example 7.

[0048] Fig.15 It is a cross-sectional view showing the lens structure of the optical system of Example 8.

[0049] Fig.16 These are various aberration diagrams of the optical system of Example 8.

[0050] Fig.17It is a cross-sectional view showing the lens structure of the optical system of Example 9.

[0051] Fig.18 These are various aberration diagrams of the optical system of Example 9.

[0052] Fig.19 It is a cross-sectional view showing the lens structure of the optical system of Example 10.

[0053] Fig. 20 These are various aberration diagrams of the optical system of Example 10.

[0054] Fig.21 It is a cross-sectional view showing the lens structure of the optical system of Example 11.

[0055] Fig. 22 These are various aberration diagrams of the optical system of Example 11.

[0056] Fig.23 It is a cross-sectional view showing the lens structure of the optical system of Example 12.

[0057] Fig.24 These are various aberration diagrams of the optical system of Example 12.

[0058] Fig.25 A cross-sectional view of a camera equipped with the above-mentioned optical system is shown.

[0059] Fig.26 It is a flowchart for explaining the manufacturing method of the above-mentioned optical system. DETAILED DESCRIPTION

[0060] Hereinafter, preferred embodiments will be described with reference to the drawings.

[0061] like Figure 1 As shown in FIG. 1 , the optical system OL of this embodiment is configured to include, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In addition, the first lens group G1 is configured to include, in order from the object side, at least two negative lenses (for example, Figure 1 In the example, negative meniscus lens L1n1 and aspherical negative lens L1n2), positive lens (for example, Figure 1 In the example, the first positive lens L1p1 is a biconvex positive lens, hereinafter referred to as the "first positive lens") and the image side negative lens (for example, Figure 1 In the example, it is a negative meniscus lens L1nr). With this structure, a high-performance optical system with a wide field of view can be obtained.

[0062] The optical system OL of the present embodiment preferably satisfies the following conditional expression (1).

[0063] 90.00° < ωmax (1)

[0064] in,

[0065] ωmax: Maximum value of half field angle of the optical system OL [°]

[0066] Conditional expression (1) specifies the maximum value of the half-angle of view of the optical system OL. By satisfying this conditional expression (1), an optical system OL with a wide angle of view can be obtained. When the lower limit value of conditional expression (1) is lower than the lower limit value, the wide angle of view required as an ultra-wide-angle lens is lost, which is not preferred. In addition, in order to reliably obtain the effect of conditional expression (1), it is more preferred to make the lower limit value of conditional expression (1) 95.00°, 97.50°, 100.00°, and further 105.00°.

[0067] The optical system OL of the present embodiment preferably satisfies the following conditional expression (2).

[0068] 0.300 <(-f1) / θmax < 9.200 (2)

[0069] in,

[0070] f1: Focal length of the first lens group G1

[0071] θmax: Maximum value of half field angle of optical system OL [radian]

[0072] Conditional expression (2) specifies the ratio of the focal length of the first lens group to the maximum value of the half-angle of view of the optical system OL. Here, there is a relationship of θmax=ωmax×π / 180 (π is pi). By satisfying this conditional expression (2), an optical system OL having a wide angle of view and good optical performance can be obtained. When it is lower than the lower limit value of conditional expression (2), the optical power (power) of the first lens group G1 becomes too strong relative to the angle of view, and the field curvature worsens, which is not preferred. In order to reliably obtain the effect of conditional expression (2), it is more preferable to set the lower limit of conditional expression (2) to 0.500, 0.600, 0.700, 0.800, 0.850, 0.900, 0.950, 1.000, 1.050, 1.100, 1.150, 1.200, 1.250, 1.300, 1.350, 1.400, and further to 1.450. In addition, when the upper limit of conditional expression (2) is exceeded, the refractive power (power) of the first lens group G1 becomes too weak relative to the field angle, and the field curvature deteriorates, which is not preferable. In addition, when the field angle is narrowed, the wide field angle required as an ultra-wide-angle lens is lost, which is not preferable. In order to reliably obtain the effect of conditional expression (2), it is more preferable to set the upper limit value of conditional expression (2) to 8.500, 7.500, 6.750, 6.500, 6.250, 6.000, 5.750, 5.550, 5.250, 5.000, 4.850, 4.700, 4.500, or further to 4.250.

[0073] The optical system OL of the present embodiment preferably satisfies the following conditional expression (3).

[0074] 0.280 < D12 / (-f1) < 1.200 (3)

[0075] in,

[0076] D12: The distance on the optical axis between the two negative lenses of the first lens group G1 arranged closest to the object

[0077] f1: Focal length of the first lens group G1

[0078] Conditional expression (3) specifies the ratio of the distance on the optical axis between the two negative lenses of the first lens group G1 that are arranged closest to the object to the focal length of the first lens group G1. By satisfying this conditional expression (3), it is possible to obtain good optical performance of the optical system OL, and by appropriately configuring the two negative lenses (L1n1, L1n2) of the first lens group G1 that are arranged closest to the object, the optical system OL can be miniaturized. When the lower limit value of conditional expression (3) is lower than, when various aberrations are corrected, when the outer diameter increases during manufacturing, the two negative lenses (L1n1, L1n2) of the first lens group G1 that are arranged closest to the object will interfere, so it is not preferred. In addition, it is difficult to correct field curvature, coma, and chromatic aberration of magnification, so it is not preferred. In addition, in order to reliably obtain the effect of conditional formula (3), it is more preferred that the lower limit value of conditional formula (3) is 0.300, 0.325, 0.340, 0.355, 0.370, 0.390, 0.400, 0.420, and further 0.430. In addition, when the upper limit value of conditional formula (3) is exceeded, the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct image plane curvature, coma, and chromatic aberration of magnification, so it is not preferred. In addition, in order to reliably obtain the effect of conditional formula (3), it is more preferred that the upper limit value of conditional formula (3) is 1.185, 1.150, 1.125, 1.100, 1.080, 1.050, 1.025, and further 1.000.

[0079] The optical system OL of the present embodiment preferably satisfies the following conditional expression (4).

[0080] -10.000<(Lnr1-Lpr2) / (Lnr1+Lpr2)≤0.000 (4)

[0081] in,

[0082] Lpr2: radius of curvature of the image side lens surface of the first positive lens L1p1 constituting the first lens group G1

[0083] Lnr1: The curvature radius of the object-side lens surface of the rear negative lens L1nr constituting the first lens group G1

[0084] Conditional expression (4) specifies the shape factor of the air lens between the first positive lens L1p1 and the rear negative lens L1nr constituting the first lens group G1. By satisfying the conditional expression (4), an optical system OL having a wide field angle and good optical performance can be obtained. When it is lower than the lower limit value of the conditional expression (4), it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of the conditional expression (4), it is more preferred to make the lower limit value of the conditional expression (4) -7.500, -5.000, -3.000, -2.000, -1.750, -1.500, -1.250, -1.150, -1.000, and further -0.950. In addition, when it exceeds the upper limit value of the conditional expression (4), it is difficult to correct spherical aberration and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (4), it is more preferable to set the upper limit value of conditional expression (4) to -0.100, -0.250, -0.400, -0.417, -0.500, or even -0.550.

[0085] The optical system OL of the present embodiment preferably satisfies the following conditional expression (5).

[0086] 0.200 < (-f1) / f2 < 4.500 (5)

[0087] in,

[0088] f1: Focal length of the first lens group G1

[0089] f2: Focal length of the second lens group G2

[0090] Conditional expression (5) specifies the ratio of the focal length of the first lens group G1 to the focal length of the second lens group G2. By satisfying conditional expression (5), good optical performance of the optical system OL can be obtained, and the optical power (power) of the first lens group G1 and the second lens group G2 can be appropriately specified. When the lower limit value of conditional expression (5) is exceeded, the optical power (power) of the first lens group G1 becomes stronger than that of the second lens group G2, and it is difficult to correct coma, field curvature, and astigmatism, which is not preferred. In order to reliably obtain the effect of conditional expression (5), it is more preferable to set the lower limit of conditional expression (5) to 0.250, 0.275, 0.300, 0.320, 0.340, 0.350, 0.370, 0.385, 0.400, 0.425, 0.450, 0.475, 0.500, 0.520, 0.535, and further to 0.550. In addition, when the upper limit of conditional expression (5) is exceeded, the optical power (power) of the first lens group G1 becomes weaker than that of the second lens group G2 and the diameter of the first lens group G1 increases, which is not preferable. Moreover, when the optical power (power) of the second lens group G2 becomes stronger, the spherical aberration worsens, which is not preferable. In order to reliably obtain the effect of conditional expression (5), it is more preferable to set the upper limit value of conditional expression (5) to 4.250, 4.000, 3.750, 3.500, 3.400, 3.300, 3.200, 3.100, 3.025, 2.800, 2.500, 2.250, 2.000, 1.800, or further to 1.600.

[0091] The optical system OL of the present embodiment preferably satisfies the following conditional expression (6).

[0092] 0.130 < Dn / f < 3.500 (6)

[0093] in,

[0094] Dn: The thickness on the optical axis of the negative lens disposed most toward the image side among the negative lenses included in the first lens group G1

[0095] f: focal length of the entire optical system OL

[0096] Conditional expression (6) specifies the ratio of the thickness on the optical axis of the negative lens (L1nr) disposed closest to the image side among the negative lenses included in the first lens group G1 to the focal length of the entire optical system OL. By satisfying this conditional expression (6), it is possible to obtain an optical system OL that achieves a wide field of view, is compact, and has good optical performance. When the conditional expression (6) is lower than the lower limit, the total length of the optical system OL becomes larger, so it is not preferred. In addition, it is difficult to correct coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (6), it is more preferred to make the lower limit of conditional expression (6) 0.150, 0.180, 0.200, 0.210, 0.220, and further 0.230. In addition, when the upper limit of conditional expression (6) is exceeded, it is difficult to correct coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (6), it is more preferable to set the upper limit value of conditional expression (6) to 3.450, 3.400, 3.350, 3.300, 3.250, 3.200, 3.150, or further to 3.120.

[0097] The optical system OL of the present embodiment preferably satisfies the following conditional expression (7).

[0098] 0.020 < Dn / (-f1) < 1.500 (7)

[0099] in,

[0100] Dn: The thickness on the optical axis of the negative lens disposed most toward the image side among the negative lenses included in the first lens group G1

[0101] f1: Focal length of the first lens group G1

[0102] Conditional expression (7) specifies the ratio of the thickness on the optical axis of the negative lens (L1nr) disposed closest to the image side among the negative lenses included in the first lens group G1 to the focal length of the first lens group G1. By satisfying this conditional expression (7), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (7), it is difficult to ensure the back focus of the optical system OL, so it is not preferred. In addition, it is difficult to correct image curvature and astigmatism, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (7), it is more preferred to make the lower limit value of conditional expression (7) 0.030, 0.040, 0.045, 0.050, 0.055, 0.060, 0.065, and further 0.068. In addition, when it exceeds the upper limit value of conditional expression (7), it is difficult to correct coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (7), it is more preferable to set the upper limit value of conditional expression (7) to 1.400, 1.350, 1.300, 1.250, 1.200, 1.150, 1.100, 1.050, 1.000, or further to 0.940.

[0103] The optical system OL of the present embodiment preferably satisfies the following conditional expression (8).

[0104] 1.000 < (-f1) / f < 7.000 (8)

[0105] in,

[0106] f1: Focal length of the first lens group G1

[0107] f: focal length of the entire optical system OL

[0108] Conditional expression (8) specifies the ratio of the focal length of the first lens group G1 to the focal length of the entire optical system OL. By satisfying the conditional expression (8), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When the conditional expression (8) is lower than the lower limit, it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (8), it is more preferred to make the lower limit of conditional expression (8) 1.100, 1.200, 1.300, 1.400, 1.500, 1.550, 1.600, 1.650, 1.700, 1.750, 1.800, and further 1.850. In addition, when the upper limit of conditional expression (8) is exceeded, the diameter of the first lens group G1 becomes large, so it is not preferred. In addition, it is difficult to correct field curvature and astigmatism, so it is not preferred. In order to reliably obtain the effect of conditional expression (8), it is more preferable to set the upper limit value of conditional expression (8) to 6.800, 6.500, 6.300, 6.150, 6.000, 5.850, 5.600, 5.500, 5.400, 5.300, 5.250, or further to 5.200.

[0109] The optical system OL of the present embodiment preferably satisfies the following conditional expression (9).

[0110] 2.500 < f2 / f < 4.500 (9)

[0111] in,

[0112] f2: Focal length of the second lens group G2

[0113] f: focal length of the entire optical system OL

[0114] Conditional expression (9) specifies the ratio of the focal length of the second lens group G2 to the focal length of the entire optical system OL. By satisfying the conditional expression (9), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit of conditional expression (9), it is difficult to correct image curvature, coma, and chromatic aberration of magnification, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (9), it is more preferred to make the lower limit of conditional expression (9) 2.550, 2.600, 2.650, 2.680, and further 2.700. In addition, when it exceeds the upper limit of conditional expression (9), the optical focal length (power) of the second lens group G2 becomes weak, and the total length of the optical system OL becomes larger, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (9), it is more preferable to set the upper limit value of conditional expression (9) to 4.300, 4.150, 4.000, 3.980, 3.950, 3.930, 3.900, or further to 3.890.

[0115] The optical system OL of the present embodiment preferably satisfies the following conditional expression (10).

[0116] 0.100 < D12 / (-f11) < 0.500 (10)

[0117] in,

[0118] D12: The distance on the optical axis between the two negative lenses of the first lens group G1 arranged closest to the object side

[0119] f11: Focal length of the negative lens located closest to the object in the first lens group G1

[0120] Conditional expression (10) specifies the ratio of the distance on the optical axis between the two negative lenses (L1n1, L1n2) of the first lens group G1 arranged on the most object side to the focal length of the negative lens (L1n1) of the first lens group G1 arranged on the most object side. By satisfying this conditional expression (10), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (10), the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (10), it is more preferred to make the lower limit value of conditional expression (10) 0.110, 0.125, 0.140, 0.145, 0.150, 0.155, and further 0.160. In addition, when it exceeds the upper limit value of conditional expression (10), the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct field curvature, coma, and chromatic aberration of magnification, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (10), it is more preferred to make the upper limit value of conditional expression (10) 0.490, 0.475, 0.450, 0.425, 0.410, 0.400, 0.390, 0.380, 0.375, and further 0.370.

[0121] The optical system OL of the present embodiment preferably satisfies the following conditional expression (11).

[0122] 0.015 <DS / (-f1)<1.500 (11)

[0123] in,

[0124] DS: The distance on the optical axis from the lens surface closest to the image side of the first lens group G1 to the lens surface closest to the object side of the second lens group G2

[0125] f1: Focal length of the first lens group G1

[0126] Conditional formula (11) specifies the ratio of the distance on the optical axis from the lens surface closest to the image side of the first lens group G1 to the lens surface closest to the object side of the second lens group G2 to the focal length of the first lens group G1. By satisfying this conditional formula (11), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional formula (11), the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional formula (11), it is more preferred to make the lower limit value of conditional formula (11) 0.018, 0.020, 0.022, and further 0.024. In addition, when the upper limit value of conditional formula (11) is exceeded, the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (11), it is more preferable to set the upper limit value of conditional expression (11) to 1.450, 1.400, 1.350, 1.300, 1.250, 1.200, 1.185, 1.170, 1.150, or further to 1.125.

[0127] The optical system OL of the present embodiment preferably satisfies the following conditional expression (12).

[0128] 0.005 <DS / (-f11)<0.250 (12)

[0129] in,

[0130] DS: The distance on the optical axis from the lens surface closest to the image side of the first lens group G1 to the lens surface closest to the object side of the second lens group G2

[0131] f11: Focal length of the negative lens located closest to the object in the first lens group G1

[0132] Conditional expression (12) specifies the ratio of the distance on the optical axis from the lens surface closest to the image side of the first lens group G1 to the lens surface closest to the object side of the second lens group G2 to the focal length of the negative lens (L1n1) of the first lens group G1 arranged closest to the object side. By satisfying this conditional expression (12), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (12), the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (12), it is more preferred to make the lower limit value of conditional expression (12) 0.007, 0.008, and further 0.009. In addition, when the upper limit value of conditional expression (12) is exceeded, the total length of the optical system OL becomes large, so it is not preferred. In addition, it is difficult to correct spherical aberration and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (12), it is more preferable to set the upper limit value of conditional expression (12) to 0.235, 0.220, 0.200, 0.180, 0.150, 0.125, 0.110, or further to 0.100.

[0133] The optical system OL of the present embodiment preferably satisfies the following conditional expression (13).

[0134] -1.000<(L1r2-L1r1) / (L1r2+L1r1)<-0.250 (13)

[0135] in,

[0136] L1r1: The curvature radius of the object-side lens surface of the negative lens disposed most on the object side of the first lens group G1

[0137] L1r2: The curvature radius of the image side lens surface of the negative lens disposed most on the object side of the first lens group G1

[0138] Conditional expression (13) specifies the shape factor of the negative lens (L1n1) of the first lens group G1 which is arranged closest to the object side. By satisfying the conditional expression (13), an optical system OL having good optical performance can be obtained. When the conditional expression (13) is lower than the lower limit value, it is difficult to correct image curvature and astigmatism, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (13), it is more preferred to make the lower limit value of conditional expression (13) -0.900, -0.750, -0.700, -0.676, -0.650, -0.625, -0.600, -0.575, -0.550, and further -0.525. In addition, when the upper limit value of conditional expression (13) is exceeded, it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (13), it is more preferable to set the upper limit value of conditional expression (13) to -0.270, -0.282, -0.290, -0.300, -0.305, -0.310, -0.315, or further to -0.320.

[0139] The optical system OL of the present embodiment preferably satisfies the following conditional expression (14).

[0140] 8.500 < TL / f < 21.000 (14)

[0141] in,

[0142] TL: Total length of the optical system OL

[0143] f: focal length of the entire optical system OL

[0144] Conditional formula (14) specifies the ratio of the total length of the entire system of the optical system OL to the focal length. By satisfying the conditional formula (14), it is possible to obtain an optical system OL that achieves a wide field of view, is compact and has good optical performance. When it is lower than the lower limit value of the conditional formula (14), it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In addition, in order to reliably obtain the effect of the conditional formula (14), it is more preferred to make the lower limit value of the conditional formula (14) 8.750, 9.000, 9.250, 9.500, 9.750, 9.950, 10.000, 10.250, 10.500, 10.750, 11.000, and further 11.250. In addition, when it exceeds the upper limit value of the conditional formula (14), the total length of the optical system OL becomes larger, so it is not preferred. In addition, it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In order to more reliably obtain the effect of conditional expression (14), it is more preferable to set the upper limit value of conditional expression (14) to 20.600, 20.100, 20.000, 19.850, 19.700, 19.500, or further to 19.250.

[0145] The optical system OL of this embodiment preferably satisfies the following conditional expression (15).

[0146] 0.800 < BF / f < 2.800 (15)

[0147] in,

[0148] BF: Back focal length of the optical system OL

[0149] f: focal length of the entire optical system OL

[0150] Conditional expression (15) specifies the ratio of the back focal length of the entire system of the optical system OL to the focal length. By satisfying the conditional expression (15), it is possible to obtain an optical system OL that achieves a wide field of view, is compact, and has good optical performance. When it is lower than the lower limit value of the conditional expression (15), it is difficult to correct distortion, image curvature, and astigmatism, so it is not preferred. In addition, in order to more reliably obtain the effect of the conditional expression (15), it is more preferred to make the lower limit value of the conditional expression (15) 0.825, 0.850, 0.875, and further 0.900. In addition, when the upper limit value of the conditional expression (15) is exceeded, the diameter of the first lens group G1 becomes large, so it is not preferred. In addition, it is difficult to correct distortion, image curvature, and astigmatism, so it is not preferred. In order to more reliably obtain the effect of conditional expression (15), it is more preferable to set the upper limit value of conditional expression (15) to 2.700, 2.600, 2.550, 2.500, 2.450, 2.400, or further to 2.380.

[0151] The optical system OL of this embodiment preferably satisfies the following conditional expression (16).

[0152] 5.000 < ΣD1 / f < 13.000 (16)

[0153] in,

[0154] ΣD1: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group G1

[0155] f: focal length of the entire optical system OL

[0156] Conditional expression (16) specifies the ratio of the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group G1 to the focal length of the entire system of the optical system OL. By satisfying this conditional expression (16), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (16), it is difficult to correct spherical aberration, coma, and image curvature, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (16), it is more preferred to make the lower limit value of conditional expression (16) 5.250, 5.500, 5.800, 6.000, and further 6.100. In addition, when the upper limit value of conditional expression (16) is exceeded, the total length of the optical system OL increases, so it is not preferred. In addition, it is difficult to correct distortion and image curvature, so it is not preferred. In order to reliably obtain the effect of conditional expression (16), it is more preferable to set the upper limit value of conditional expression (16) to 12.500, 12.000, 11.850, 11.800, 11.750, or further to 11.700.

[0157] The optical system OL of this embodiment preferably satisfies the following conditional expression (17).

[0158] 2.800 < ΣD2 / f < 8.200 (17)

[0159] in,

[0160] ΣD2: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the second lens group G2

[0161] f: focal length of the entire optical system OL

[0162] Conditional expression (17) specifies the ratio of the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the second lens group G2 to the focal length of the entire system of the optical system OL. By satisfying this conditional expression (17), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (17), it is difficult to correct image curvature and astigmatism, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (17), it is more preferred to make the lower limit value of conditional expression (17) 3.000, 3.150, 3.300, 3.450, 3.500, 3.650, 3.750, and further 3.800. In addition, when it exceeds the upper limit value of conditional expression (17), the total length of the optical system OL increases, so it is not preferred. In addition, it is difficult to correct spherical aberration, coma, and image curvature, so it is not preferred. In order to reliably obtain the effect of conditional expression (17), it is more preferable to set the upper limit value of conditional expression (17) to 8.000, 7.750, 7.550, 7.400, 7.150, 7.000, 6.850, 6.700, 6.500, 6.350, 6.200, 6.100, or further to 6.000.

[0163] The optical system OL of this embodiment preferably satisfies the following conditional expression (18).

[0164] 1.000<(-f1ne) / f<3.000 (18)

[0165] in,

[0166] f1ne: The composite focal length of the negative lens of the first lens group G1 that is arranged on the object side relative to the first positive lens

[0167] f: focal length of the entire optical system OL

[0168] Conditional expression (18) specifies the ratio of the synthetic focal length of the negative lens of the first lens group G1 arranged on the object side relative to the first positive lens to the focal length of the entire system of the optical system OL. By satisfying this conditional expression (18), it is possible to obtain an optical system OL that achieves a wide field of view, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (18), it is difficult to correct image curvature and astigmatism, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (18), it is more preferred to make the lower limit value of conditional expression (18) 1.050, 1.100, 1.115, 1.200, 1.225, 1.250, 1.275, 1.290, and further 1.300. In addition, when it exceeds the upper limit value of conditional expression (18), the diameter of the first lens group G1 becomes large, so it is not preferred. In addition, it is difficult to correct image curvature and astigmatism, so it is not preferred. In order to reliably obtain the effect of conditional expression (18), it is more preferable to set the upper limit value of conditional expression (18) to 2.850, 2.700, 2.600, 2.500, 2.350, 2.200, 2.150, 2.100, or further to 2.080.

[0169] The optical system OL of this embodiment preferably satisfies the following conditional expression (19).

[0170] 1.200 < f22 / f < 4.100 (19)

[0171] in,

[0172] f22: Focal length of the positive lens of the cemented lens located closest to the object among the cemented lenses included in the second lens group G2

[0173] f: focal length of the entire optical system OL

[0174] Conditional expression (19) specifies the ratio of the focal length of the positive lens (L22) of the cemented lens (CL21) located closest to the object side among the cemented lenses included in the second lens group G2 to the focal length of the entire optical system OL. By satisfying the conditional expression (19), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When it is lower than the lower limit value of the conditional expression (19), it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In addition, in order to reliably obtain the effect of the conditional expression (19), it is more preferred to make the lower limit value of the conditional expression (19) 1.300, 1.450, 1.550, 1.650, 1.700, 1.750, 1.800, 1.850, 1.900, and further 1.950. In addition, when it exceeds the upper limit value of the conditional expression (19), it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (19), it is more preferable to set the upper limit value of conditional expression (19) to 4.000, 3.850, 3.700, 3.650, 3.500, 3.350, 3.200, 3.100, 3.000, or further to 2.950.

[0175] The optical system OL of this embodiment preferably satisfies the following conditional expression (20).

[0176] -8.000 < f2CL / (-f1) < 90.000 (20)

[0177] in,

[0178] f2CL: Focal length of the cemented lens disposed closest to the object among the cemented lenses included in the second lens group G2

[0179] f: focal length of the entire optical system OL

[0180] Conditional expression (20) specifies the ratio of the focal length of the cemented lens (CL21) disposed on the most object side among the cemented lenses included in the second lens group G2 to the focal length of the entire optical system OL. By satisfying this conditional expression (20), it is possible to obtain an optical system OL that achieves a wide field angle, is compact, and has good optical performance. When the lower limit value of conditional expression (20) is lower than the lower limit value, the focal length (power) of the cemented lens disposed on the most object side among the cemented lenses included in the second lens group G2 becomes stronger, and it is difficult to correct spherical aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (20), it is more preferred to make the lower limit value of conditional expression (20) -7.500, -7.000, -6.700, -6.500, -6.250, -6.000, -5.750, -5.550, and further -5.540. In addition, when the upper limit value of conditional expression (20) is exceeded, the refractive power (power) of the first lens group G1 becomes strong, and it is difficult to correct spherical aberration, coma, and field curvature, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (20), it is more preferred to make the upper limit value of conditional expression (20) 80.000, 70.000, 64.500, 60.000, 55.000, 50.000, 45.000, and further 40.000.

[0181] The optical system OL of this embodiment preferably satisfies the following conditional expression (21).

[0182] 0.500<(-f1ne) / θmax<4.500 (21)

[0183] in,

[0184] f1ne: The composite focal length of the negative lens of the first lens group G1 that is arranged on the object side relative to the first positive lens

[0185] θmax: Maximum value of half field angle of optical system OL [radian]

[0186] Conditional expression (21) specifies the ratio of the synthetic focal length of the negative lens of the first lens group G1, which is arranged on the object side compared to the first positive lens, to the maximum value of the half angle of view of the optical system OL. By satisfying this conditional expression (21), it is possible to obtain an optical system OL that achieves a wide angle of view, is compact, and has good optical performance. When the value is lower than the lower limit of conditional expression (21), the synthetic optical focal length (power) of the negative lens of the first lens group G1, which is arranged on the object side compared to the first positive lens, is too strong relative to the angle of view of the optical system OL, and the image curvature deteriorates, which is not preferred. In addition, when the angle of view of the optical system OL becomes smaller, it is not preferred because the wide angle of view required as an ultra-wide-angle lens is lost. In order to reliably obtain the effect of conditional expression (21), it is more preferable to set the lower limit of conditional expression (21) to 0.525, 0.540, 0.550, 0.575, 0.590, 0.625, 0.800, 0.850, 0.900, 0.950, 0.975, and further to 1.000. In addition, when the upper limit of conditional expression (21) is exceeded, the synthetic optical power (power) of the negative lens arranged on the object side relative to the first positive lens of the first lens group G1 is too weak with respect to the field angle of the optical system OL, and the field curvature deteriorates, which is not preferable. In order to reliably obtain the effect of conditional expression (21), it is more preferable to set the upper limit value of conditional expression (21) to 4.000, 3.750, 3.500, 3.200, 3.000, 2.750, 2.500, 2.250, 2.000, 1.850, or further to 1.700.

[0187] The optical system OL of this embodiment preferably satisfies the following conditional expression (22).

[0188] 32.000 < νda < 70.000 (22)

[0189] in,

[0190] νda: Average value of the Abbe number of the medium of the negative lens arranged on the object side relative to the first positive lens of the first lens group G1 for the d-line

[0191] Conditional expression (22) specifies the average value of the Abbe number of the medium of the lens arranged on the object side relative to the first positive lens of the first lens group G1 for the d-line. By satisfying this conditional expression (22), it is possible to obtain an optical system OL that achieves a wide angle of view, is compact, and has good optical performance. When it is lower than the lower limit value of conditional expression (22), it is difficult to correct the color components of magnification chromatic aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (22), it is more preferred to make the lower limit value of conditional expression (22) 32.500, 33.000, 33.500, and further 34.000. In addition, when it exceeds the upper limit value of conditional expression (22), it is difficult to correct the color components of magnification chromatic aberration and coma, so it is not preferred. In addition, in order to reliably obtain the effect of conditional expression (22), it is more preferred to make the upper limit value of conditional expression (22) 68.000, and further 67.200.

[0192] The optical system OL of this embodiment preferably satisfies the following conditional expression (23).

[0193] 0.250<(L3r1-L2r2) / (L3r1+L2r2)<1.500 (23)

[0194] in,

[0195] L2r2: The curvature radius of the image side lens surface of the second lens arranged from the object side in the first lens group G1

[0196] L3r1: The curvature radius of the object-side lens surface of the third lens arranged from the object side in the first lens group G1

[0197] Conditional expression (23) specifies the shape factor of the air lens between the second lens (L12) and the third lens (L13) of the first lens group G1 from the object side. By satisfying the conditional expression (23), an optical system OL having good optical performance can be obtained. When it is lower than the lower limit value of the conditional expression (23), it is difficult to correct image curvature and astigmatism, so it is not preferred. In addition, in order to reliably obtain the effect of the conditional expression (23), it is more preferred to make the lower limit value of the conditional expression (23) 0.280, 0.300, 0.325, 0.340, and further 0.380. In addition, when it exceeds the upper limit value of the conditional expression (23), it is difficult to correct image curvature, astigmatism, and coma, so it is not preferred. In order to reliably obtain the effect of conditional expression (23), it is more preferable to set the upper limit value of conditional expression (23) to 1.400, 1.300, 1.250, 1.200, 1.175, 1.150, or further to 1.120.

[0198] In the optical system OL of this embodiment, it is preferred that the lens closest to the object side of the second lens group G2 has an object side lens surface and an image side lens surface formed into an aspherical shape. When configured as described above, coma, field curvature, astigmatism, and distortion can be corrected.

[0199] In addition, the contents described below can be appropriately adopted within a range not impairing the optical performance.

[0200] In this embodiment, although a two-group optical system OL is shown, the above-mentioned configuration conditions and the like can also be applied to other group structures such as three groups and four groups. In addition, a structure in which a lens or a lens group is added to the object side, or a structure in which a lens or a lens group is added to the image side can also be used. In addition, a lens group refers to a portion having at least one lens separated by an air space that changes when zooming.

[0201] In addition, it is also possible to use a focus lens group that moves a single lens group or a plurality of lens groups, or a part of the lens group, in the direction of the optical axis to focus from an infinitely distant object to a close-up object. In this case, the focus lens group can also be applied to autofocus, and is also suitable for motor drive (such as an ultrasonic motor) for autofocus. In particular, it is preferred that the entire optical system OL is a focus lens group.

[0202] Alternatively, the lens group or part of the lens group may be moved in a manner having a component perpendicular to the optical axis, or rotated (swayed) in a plane including the optical axis, thereby correcting image jitter caused by hand shaking. In particular, it is preferred that the entire second lens group G2 or a part of the second lens group G2 be an anti-shake lens group.

[0203] In addition, the lens surface can be formed by a spherical surface or a plane, and can also be formed by an aspherical surface. When the lens surface is a spherical surface or a plane, lens processing and assembly adjustment become easy, and the degradation of optical performance caused by errors in processing and assembly adjustment is prevented, so it is preferred. In addition, in the case of image plane deviation, the degradation of drawing performance is also less, so it is preferred. When the lens surface is an aspherical surface, the aspherical surface can also be an aspherical surface based on grinding processing, a glass molded aspherical surface in which glass is formed into an aspherical shape by a mold, and a composite aspherical surface in which resin is formed into an aspherical shape on the surface of the glass. In addition, the lens surface can also be a diffraction surface, and the lens can also be a refractive index distribution lens (GRIN lens) or a plastic lens.

[0204] Although the aperture stop S is preferably disposed between the first lens group G1 and the second lens group G2, it is also possible not to provide a member serving as the aperture stop, but to use the lens frame instead to perform its function.

[0205] Furthermore, an antireflection film having high transmittance in a wide wavelength range may be applied to each lens surface in order to reduce glare and ghosting and achieve high optical performance with high contrast.

[0206] In addition, the above-described structures and conditions each exert the above-described effects, and are not limited to satisfying all structures and conditions. The above-described effects can be obtained even if any one structure or condition, or any combination of structures or conditions, is satisfied.

[0207] exist Fig.25 , a schematic cross-sectional view of a single-lens reflex camera 1 (hereinafter simply referred to as a camera) is shown as an optical device having the above-mentioned optical system OL. In the camera 1, light from an object (subject) not shown in the figure is focused by a photographic lens 2 (optical system OL) and imaged on a focus plate 4 via a quick return mirror 3. Furthermore, the light imaged on the focus plate 4 is reflected multiple times by a pentaprism 5 and introduced into an eyepiece 6. Thus, the photographer can observe the object (subject) image through the eyepiece 6 as an erect image.

[0208] In addition, when the photographer presses the release button (not shown), the quick return mirror 3 retreats out of the optical path, and the light of the object (subject) (not shown) focused by the photographic lens 2 forms a subject image on the imaging element 7. Thus, the light from the object (subject) is photographed by the imaging element 7 and recorded as the object (subject) image in the memory (not shown). Thus, the photographer can take pictures of the object (subject) based on the present camera 1. In addition, as described in Fig.25 The camera 1 may also be detachably holding the photographic lens 2, or may be formed integrally with the photographic lens 2. In addition, the camera 1 may be a so-called single-lens reflex camera, or may be a compact camera without a quick return mirror or a single-lens reflex camera without a mirror.

[0209] Below, refer to Fig.26 The manufacturing method of the optical system OL of the present embodiment is briefly described. First, the first lens group G1, the aperture stop S, and the second lens group G2 of the optical system OL are prepared by arranging each lens (step S100). In addition, at least two negative lenses, a positive lens, and a rear negative lens are arranged in the first lens group G1 in order from the object side (step S200). And, each lens group and the aperture stop S are arranged in a manner that satisfies the conditions based on a predetermined conditional expression (for example, the above-mentioned conditional expression (1)) (step S300).

[0210] Specifically, in this embodiment, for example, Figure 1As shown, as the optical system OL, a negative meniscus lens L1n1 with a convex surface facing the object side, a negative meniscus-shaped aspheric negative lens L1n2 with a convex surface facing the object side, a biconvex positive lens L1p1, and a negative meniscus lens L1nr with a concave surface facing the object side are sequentially arranged from the object side as the first lens group G1, and a positive meniscus lens L21 facing the object side, a cemented positive lens CL21 formed by cementing a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24 are arranged as the second lens group G2, the lens surface on the object side and the lens surface on the image side of the aspheric negative lens L1n2 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric. And, the lens groups and aperture stop S prepared in this way are arranged in the above order to manufacture the optical system OL.

[0211] With the above-described configuration, it is possible to provide a compact optical system having a wide viewing angle and excellent optical performance, an optical device including the optical system, and a method for manufacturing the optical system.

[0212] [Example]

[0213] Hereinafter, various embodiments of the present application will be described according to the accompanying drawings. Figure 1 , Figure 3 , Figure 5 , Figure 7 , Fig. 9 , Fig.11 , Fig.13 , Fig.15 , Fig.17 , Fig.19 , Fig.21 as well as Fig.23 It is a cross-sectional view showing the structure and power distribution of the optical system OL (OL1 to OL12) according to each embodiment.

[0214] In each embodiment, the aspheric surface is represented by the following formula (a) when the height in the direction perpendicular to the optical axis is y, the distance along the optical axis from the tangent plane of the vertex of each aspheric surface at the height y to each aspheric surface (the amount of concavity) is S(y), the radius of curvature of the reference spherical surface (paraxial radius of curvature) is r, the conic constant is K, and the n-order aspheric coefficient is An. In the following embodiments, "En" represents "×10 -n ”.

[0215] S(y)=(y 2 / r) / {1+(1-K×y 2 / r 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8+A10×y 10 (a)

[0216] In each example, the two-dimensional aspheric coefficient A2 is 0. In the table of each example, an aspheric surface is marked with an * on the right side of the surface number.

[0217] [First embodiment]

[0218] Figure 1 1 is a diagram showing the structure of an optical system OL1 according to Example 1. The optical system OL1 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0219] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0220] The second lens group G2 is composed, from the object side, of a positive meniscus lens L21 with its convex surface facing the object side, a joined positive lens CL21 formed by joining a double convex positive lens L22 and a double concave negative lens L23, and a double convex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0221] Furthermore, in the optical system OL1 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0222] Table 1 below shows the values ​​of parameters of the optical system OL1. In Table 1, f shown in the overall parameters represents the focal length of the entire system, FNO represents the F value, 2ω represents the angle of view [°], Y represents the maximum image height, BF represents the back focal length converted to air, and TL represents the value of the total length converted to air. Here, the back focal length BF represents the distance on the optical axis from the lens surface closest to the image side (the 16th surface in the first embodiment) to the image surface I, and the total length TL represents the distance on the optical axis from the lens surface closest to the object side (the 1st surface in the first embodiment) to the image surface I. In addition, the first column m in the lens data shows the order of the lens surfaces from the object side along the traveling direction of the light (surface number), the second column r shows the curvature radius of each lens surface, the third column d shows the distance on the optical axis from each optical surface to the next optical surface (surface spacing), and the fourth column nd and the fifth column νd show the refractive index and Abbe number for the d-line (λ=587.6nm). In addition, the curvature radius of 0.00000 indicates a flat surface, and the refractive index of air 1.00000 is omitted. In addition, the lens group focal lengths show the surface numbers and focal lengths of the initial surfaces of the first lens group G1 and the second lens group G2.

[0223] Here, although the focal length f, radius of curvature r, surface spacing d, and other length units recorded in all the following parameter values ​​are generally expressed in "mm", the same optical performance can be obtained even if the optical system is scaled up or scaled down, so it is not limited to this. In addition, the description of these reference numerals and the description of the parameter table are the same in the subsequent embodiments.

[0224] (Table 1) First embodiment

[0225] [Overall parameters]

[0226] f=1.5178

[0227] FNO=2.8586

[0228] 2ω=220.000°

[0229] Y=2.8200

[0230] BF (air equivalent length) = 2.0694

[0231] TL (air equivalent length) = 25.1694

[0232] [Lens data]

[0233]

[0234] [Focal length of lens group]

[0235] Lens group initial focal length

[0236] First lens group G1 1 -5.1458

[0237] The second lens group G2 12 4.9638

[0238] θmax=1.920

[0239] f11=-14.443

[0240] f1ne=-2.401

[0241] f22=4.236

[0242] f2CL=198.183

[0243] In the optical system OL1, the third surface, the fourth surface, the fifteenth surface, and the sixteenth surface are formed into aspherical shapes. Table 2 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0244] (Table 2)

[0245] [Aspherical surface data]

[0246]

[0247] exist Figure 2 The spherical aberration diagram, astigmatism diagram, distortion diagram and coma diagram of the optical system OL1 are shown. In each aberration diagram, ω represents the half field angle [°]. In addition, the value of the F value corresponding to the maximum aperture is shown in the spherical aberration diagram, the maximum value of the half field angle is shown in the astigmatism diagram and the distortion diagram, and the value of each half field angle is shown in the coma diagram. D represents the d line (λ=587.6nm), g represents the g line (λ=435.8nm), e represents the e line (λ=546.1nm), F represents the F line (λ=486.1nm), and C represents the C line (λ=656.3nm). In the astigmatism diagram, the solid line represents the sagittal image plane, and the dotted line represents the meridional image plane. In addition, in the aberration diagrams of the various embodiments shown below, the same reference numerals as those of the present embodiment are also used. It can be seen from these various aberration diagrams that the optical system OL1 corrects various aberrations well.

[0248] [Second embodiment]

[0249] Figure 3 1 is a diagram showing the structure of an optical system OL2 according to Example 2. The optical system OL2 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0250] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0251] The second lens group G2 is composed of, from the object side, a biconvex aspheric positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric.

[0252] Furthermore, in the optical system OL2, a filter group FL is arranged between the second lens group G2 and the image plane I.

[0253] Table 3 below shows the values ​​of the parameters of the optical system OL2.

[0254] (Table 3) Second embodiment

[0255] [Overall parameters]

[0256] f=1.4487

[0257] FNO=2.0559

[0258] 2ω=220.000°

[0259] Y=2.8200

[0260] BF (air equivalent length) = 1.9670

[0261] TL (air equivalent length) = 23.5170

[0262] [Lens data]

[0263]

[0264] [Focal length of lens group]

[0265] Lens group initial focal length

[0266] 1st lens group G1 1 -4.7278

[0267] The second lens group G2 12 4.8507

[0268] θmax=1.920

[0269] f11=-13.026

[0270] f1ne=-2.865

[0271] f22=3.948

[0272] f2CL=-24.527

[0273] In the optical system OL2, the third, fourth, tenth, eleventh, fifteenth and sixteenth surfaces are formed into aspherical shapes. Table 4 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0274] (Table 4)

[0275] [Aspherical surface data]

[0276]

[0277] exist Figure 4 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL2 are shown. From these aberration diagrams, it can be seen that the optical system OL2 corrects each aberration well.

[0278] [Third embodiment]

[0279] Figure 5 : is a diagram showing the structure of the optical system OL3 of Example 3. The optical system OL3 is composed of a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power in this order from the object side.

[0280] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0281] The second lens group G2 is composed of, from the object side, a biconvex aspheric positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric.

[0282] Furthermore, in the optical system OL3, a filter group FL is arranged between the second lens group G2 and the image plane I.

[0283] Table 5 below shows the values ​​of the parameters of the optical system OL3.

[0284] (Table 5) Example 3

[0285] [Overall parameters]

[0286] f = 1.3638

[0287] FNO = 2.0533

[0288] 2ω=220.000°

[0289] Y=2.8200

[0290] BF (air equivalent length) = 1.9370

[0291] TL (air equivalent length) = 23.4870

[0292] [Lens data]

[0293]

[0294]

[0295] [Focal length of lens group]

[0296] Lens group initial focal length

[0297] First lens group G1 1 -5.4519

[0298] The second lens group G2 12 4.7300

[0299] θmax=1.920

[0300] f11=-13.658

[0301] f1ne=-2.786

[0302] f22=3.959

[0303] f2CL=-18.969

[0304] In the optical system OL3, the third, fourth, tenth, eleventh, fifteenth and sixteenth surfaces are formed into aspherical shapes. Table 6 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0305] (Table 6)

[0306] [Aspherical surface data]

[0307]

[0308] exist Figure 6The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL3 are shown. From these aberration diagrams, it can be seen that the optical system OL3 corrects each aberration well.

[0309] [Fourth embodiment]

[0310] Figure 7 : is a figure which shows the structure of the optical system OL4 of Example 4. This optical system OL4 consists of the 1st lens group G1 with negative refractive power, the aperture stop S, and the 2nd lens group G2 with positive refractive power in this order from the object side.

[0311] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0312] The second lens group G2 is composed of, from the object side, a biconvex aspheric positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric.

[0313] Furthermore, in the optical system OL4, a filter group FL is arranged between the second lens group G2 and the image plane I.

[0314] Table 7 below shows the values ​​of the parameters of the optical system OL4.

[0315] (Table 7) Example 4

[0316] [Overall parameters]

[0317] f=1.5164

[0318] FNO=2.0505

[0319] 2ω=220.000°

[0320] Y=2.8200

[0321] BF (air equivalent length) = 2.1818

[0322] TL (air equivalent length) = 25.0318

[0323] [Lens data]

[0324]

[0325]

[0326] [Focal length of lens group]

[0327] Lens group initial focal length

[0328] First lens group G1 1 -7.7535

[0329] The second lens group G2 12 5.2012

[0330] θmax=1.920

[0331] f11=-14.541

[0332] f1ne=-3.078

[0333] f22=4.212

[0334] f2CL=-41.086

[0335] In the optical system OL4, the third, fourth, tenth, eleventh, fifteenth and sixteenth surfaces are formed into aspherical shapes. Table 8 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0336] (Table 8)

[0337] [Aspherical surface data]

[0338]

[0339] exist Figure 8 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL4 are shown. From these aberration diagrams, it can be seen that the optical system OL4 corrects each aberration well.

[0340] [Fifth embodiment]

[0341] Fig. 9 1 is a diagram showing the structure of an optical system OL5 according to Example 5. The optical system OL5 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0342] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0343] The second lens group G2 is composed of, from the object side, a biconvex aspheric positive lens L21, a joined positive lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric.

[0344] Furthermore, in the optical system OL5 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0345] Table 9 below shows the values ​​of the parameters of the optical system OL5.

[0346] (Table 9) Fifth embodiment

[0347] [Overall parameters]

[0348] f = 1.5172

[0349] FNO = 2.8550

[0350] 2ω=220.000°

[0351] Y=2.8200

[0352] BF (air equivalent length) = 2.1270

[0353] TL (air equivalent length) = 26.1270

[0354] [Lens data]

[0355]

[0356] [Focal length of lens group]

[0357] Lens group initial focal length 1st lens group G1 1 -7.8550 The second lens group G2 12 5.2400

[0358] θmax=1.920

[0359] f11=-14.278

[0360] f1ne=-2.805

[0361] f22=4.146

[0362] f2CL=211.611

[0363] In the optical system OL5, the third, fourth, tenth, eleventh, fifteenth and sixteenth surfaces are formed into aspherical shapes. Table 10 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0364] (Table 10)

[0365] [Aspherical surface data]

[0366]

[0367] exist Fig.10 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL5 are shown. From these aberration diagrams, it can be seen that the optical system OL5 corrects each aberration well.

[0368] [Sixth embodiment]

[0369] Fig.11 The figure shows the structure of the optical system OL6 of Example 6. The optical system OL6 is composed of a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power in this order from the object side.

[0370] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0371] The second lens group G2 is composed, from the object side, of a positive meniscus lens L21 with its convex surface facing the object side, a joined positive lens CL21 formed by joining a double convex positive lens L22 and a double concave negative lens L23, and a double convex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0372] Furthermore, in the optical system OL6 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0373] Table 11 below shows the values ​​of the parameters of the optical system OL6.

[0374] (Table 11) Sixth embodiment

[0375] [Overall parameters]

[0376] f = 1.5171

[0377] FNO =2.8276

[0378] 2ω=220.000°

[0379] Y=2.8200

[0380] BF (air equivalent length) = 2.0611

[0381] TL (air equivalent length) = 25.5855

[0382] [Lens data]

[0383]

[0384]

[0385] [Focal length of lens group]

[0386] Lens group initial focal length

[0387] First lens group G1 1 -6.1237

[0388] The second lens group G2 12 5.2825

[0389] θmax=1.920

[0390] f11=-14.074

[0391] f1ne=-2.738

[0392] f22=3.901

[0393] f2CL=52.787

[0394] In the optical system OL6, the third surface, the fourth surface, the fifteenth surface, and the sixteenth surface are formed into aspherical shapes. Table 12 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0395] (Table 12)

[0396] [Aspherical surface data]

[0397]

[0398] exist Fig.12 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL6 are shown. From these aberration diagrams, it can be seen that the optical system OL6 corrects each aberration well.

[0399] [Seventh embodiment]

[0400] Fig.13: is a diagram showing the structure of an optical system OL7 according to Example 7. The optical system OL7 is composed of a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power in this order from the object side.

[0401] The first lens group G1 is composed, from the object side, of a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, and a joined positive lens formed by joining a positive meniscus lens L1p1 with its concave surface facing the object side and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical in shape.

[0402] The second lens group G2 is composed, from the object side, in sequence: a positive meniscus-shaped aspheric positive lens L21 with the convex surface toward the object side, a joined negative lens CL21 formed by joining a double convex positive lens L22 and a double concave negative lens L23, and a double convex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric surfaces, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric surfaces.

[0403] Furthermore, in the optical system OL7, a filter group FL is arranged between the second lens group G2 and the image plane I.

[0404] Table 13 below shows the values ​​of the parameters of the optical system OL7.

[0405] (Table 13) Embodiment 7

[0406] [Overall parameters]

[0407] f=1.4579

[0408] FNO=2.8496

[0409] 2ω=220.000°

[0410] Y=2.8437

[0411] BF (air equivalent length) = 2.1303

[0412] TL (air equivalent length) = 27.8853

[0413] [Lens data]

[0414]

[0415]

[0416] [Focal length of lens group]

[0417] Lens group initial focal length

[0418] 1st lens group G1 1 -4.8669

[0419] The second lens group G2 12 5.6419

[0420] θmax=1.920

[0421] f11=-12.923

[0422] f1ne=-2.442

[0423] f22=2.881

[0424] f2CL=-17.746

[0425] In the optical system OL7, the third, fourth, ninth, tenth, fourteenth and fifteenth surfaces are formed into aspherical shapes. Table 14 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0426] (Table 14)

[0427] [Aspherical surface data]

[0428]

[0429]

[0430] exist Fig.14 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL7 are shown. From these aberration diagrams, it can be seen that the optical system OL7 corrects each aberration well.

[0431] [Eighth Embodiment]

[0432] Fig.15 : is a diagram showing the structure of an optical system OL8 according to Example 8. The optical system OL8 is composed of a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power in this order from the object side.

[0433] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a negative meniscus lens L1n3 with its convex surface facing the object side, and a joined positive lens formed by joining a positive meniscus lens L1p1 with its concave surface facing the object side and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0434] The second lens group G2 is composed, from the object side, in sequence: a biconvex positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0435] Furthermore, in the optical system OL8 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0436] Table 15 below shows the values ​​of the parameters of the optical system OL8.

[0437] (Table 15) Example 8

[0438] [Overall parameters]

[0439] f=1.4929

[0440] FNO=2.8434

[0441] 2ω=220.000°

[0442] Y=2.9000

[0443] BF (air equivalent length) = 3.5356

[0444] TL (air equivalent length) = 25.0104

[0445] [Lens data]

[0446]

[0447]

[0448] [Focal length of lens group]

[0449] Lens group initial focal length

[0450] 1st lens group G1 1 -2.8222

[0451] The second lens group G2 12 4.9065

[0452] θmax=1.920

[0453] f11=-17.020

[0454] f1ne=-2.194

[0455] f22=4.097

[0456] f2CL=-11.733

[0457] In the optical system OL8, the third surface, the fourth surface, the sixteenth surface, and the seventeenth surface are formed into aspherical shapes. Table 16 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0458] (Table 16)

[0459] [Aspherical surface data]

[0460]

[0461] exist Fig.16 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL8 are shown. From these aberration diagrams, it can be seen that the optical system OL8 corrects each aberration well.

[0462] [Ninth embodiment]

[0463] Fig.17 1 is a diagram showing the structure of an optical system OL9 according to Example 9. The optical system OL9 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0464] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a negative meniscus lens L1n3 with its convex surface facing the object side, and a joined positive lens formed by joining a positive meniscus lens L1p1 with its concave surface facing the object side and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0465] The second lens group G2 is composed, from the object side, in sequence: a biconvex positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0466] Furthermore, in the optical system OL9, a filter group FL is arranged between the second lens group G2 and the image plane I.

[0467] Table 17 below shows the values ​​of the parameters of the optical system OL9.

[0468] (Table 17) 9th embodiment

[0469] [Overall parameters]

[0470] f = 1.4800

[0471] FNO = 2.8400

[0472] 2ω=220.000°

[0473] Y=2.9000

[0474] BF (air equivalent length) = 2.7363

[0475] TL (air equivalent length) = 25.2274

[0476] [Lens data]

[0477]

[0478] [Focal length of lens group]

[0479] Lens group initial focal length 1st lens group G1 1 -4.9339 The second lens group G2 12 5.1951

[0480] θmax=1.920

[0481] f11=-13.480

[0482] f1ne=-2.045

[0483] f22=3.470

[0484] f2CL=-11.245

[0485] In the optical system OL9, the third surface, the fourth surface, the sixteenth surface, and the seventeenth surface are formed into aspherical shapes. Table 18 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0486] (Table 18)

[0487] [Aspherical surface data]

[0488]

[0489] exist Fig.18 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL9 are shown. From these aberration diagrams, it can be seen that the optical system OL9 corrects each aberration well.

[0490] [10th embodiment]

[0491] Fig.19 1 is a diagram showing the structure of an optical system OL10 according to Example 10. The optical system OL10 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0492] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspherical negative lens L1n2 with its convex surface facing the object side, a negative meniscus lens L1n3 with its convex surface facing the object side, a double convex positive lens L1p1 and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspherical negative lens L1n2 are aspherical.

[0493] The second lens group G2 is composed, from the object side, of a positive meniscus lens L21 with its convex surface facing the object side, a joined positive lens CL21 formed by joining a double convex positive lens L22 and a double concave negative lens L23, and a double convex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0494] Furthermore, in the optical system OL10 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0495] Table 19 below shows the values ​​of the parameters of the optical system OL10.

[0496] (Table 19) Example 10

[0497] [Overall parameters]

[0498] f = 1.4900

[0499] FNO = 2.8500

[0500] 2ω=220.000°

[0501] Y = 2.8576

[0502] BF (air equivalent length) = 1.3763

[0503] TL (air equivalent length) = 25.0121

[0504] [Lens data]

[0505]

[0506]

[0507] [Focal length of lens group]

[0508] Lens group initial focal length

[0509] First lens group G1 1 -5.3604

[0510] The second lens group G2 12 5.3544

[0511] θmax=1.920

[0512] f11=-19.208

[0513] f1ne=-1.943

[0514] f22=3.561

[0515] f2CL=45.028

[0516] In the optical system OL10, the third surface, the fourth surface, the seventeenth surface, and the eighteenth surface are formed into aspherical shapes. Table 20 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0517] (Table 20)

[0518] [Aspherical surface data]

[0519]

[0520] exist Fig. 20 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL10 are shown. As can be seen from these aberration diagrams, the optical system OL10 corrects each aberration well.

[0521] [11th embodiment]

[0522] Fig.21 11 is a diagram showing the structure of an optical system OL11 according to Example 11. The optical system OL11 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0523] The first lens group G1 is composed, from the object side, in sequence: a negative meniscus lens L1n1 with its convex surface facing the object side, a negative meniscus aspheric negative lens L1n2 with its convex surface facing the object side, a cemented positive lens formed by cementing a negative meniscus lens L1n3 with its convex surface facing the object side and a double convex positive lens L1p1, and a negative meniscus lens L1nr with its concave surface facing the object side. The lens surface on the object side and the lens surface on the image side of the aspheric negative lens L1n2 are aspherical.

[0524] The second lens group G2 is composed, from the object side, in sequence: a positive meniscus aspheric positive lens L21 with its concave surface facing the object side, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24. The lens surface on the object side and the lens surface on the image side of the aspheric positive lens L21 are aspheric, and the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric.

[0525] Furthermore, in the optical system OL11 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0526] Table 21 below shows the values ​​of the parameters of the optical system OL11.

[0527] (Table 21) Example 11

[0528] [Overall parameters]

[0529] f=1.4036

[0530] FNO=2.5144

[0531] 2ω=220.000°

[0532] Y=2.8258

[0533] BF (air equivalent length) = 1.8104

[0534] TL (air equivalent length) = 20.2494

[0535] [Lens data]

[0536]

[0537]

[0538] [Focal length of lens group]

[0539] Lens group initial focal length

[0540] First lens group G1 1 -3.8708

[0541] The second lens group G2 12 3.8529

[0542] θmax=1.920

[0543] f11=-13.230

[0544] f1ne=-1.231

[0545] f22=3.791

[0546] f2CL=-8.191

[0547] In the optical system OL11, the third, fourth, eleventh, twelfth, sixteenth and seventeenth surfaces are formed into aspherical shapes. Table 22 below shows aspherical surface data, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0548] (Table 22)

[0549] [Aspherical surface data]

[0550]

[0551]

[0552] exist Fig. 22 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL11 are shown. As can be seen from these aberration diagrams, the optical system OL11 corrects each aberration well.

[0553] [Example 12]

[0554] Fig.23 1 is a diagram showing the structure of an optical system OL12 according to Example 12. The optical system OL12 is composed of, in order from the object side, a first lens group G1 having negative refractive power, an aperture stop S, and a second lens group G2 having positive refractive power.

[0555] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1n1 with a convex surface facing the object side, a negative meniscus lens L1n2 with a convex surface facing the object side, a biconvex positive lens L1p1, and a negative meniscus lens L1nr with a concave surface facing the object side.

[0556] The second lens group G2 is composed, from the object side, in sequence: a biconvex positive lens L21, a joined negative lens CL21 formed by joining a biconvex positive lens L22 and a biconcave negative lens L23, and a biconvex aspheric positive lens L24, wherein the lens surface on the object side and the lens surface on the image side of the aspheric positive lens L24 are aspheric shapes.

[0557] Furthermore, in the optical system OL12 , a filter group FL is arranged between the second lens group G2 and the image plane I.

[0558] Table 23 below shows the values ​​of the parameters of the optical system OL12.

[0559] (Table 23) Example 12

[0560] [Overall parameters]

[0561] f = 1.3278

[0562] FNO=2.0198

[0563] 2ω=200.000°

[0564] Y=2.1690

[0565] BF (air equivalent length) = 1.8800

[0566] TL (air equivalent length) = 15.2622

[0567] [Lens data]

[0568]

[0569] [Focal length of lens group]

[0570] Lens group initial focal length

[0571] 1st lens group G1 1 -3.9397

[0572] The second lens group G2 12 3.6107

[0573] θmax=1.745

[0574] f11=-7.287

[0575] f1ne=-2.168

[0576] f22=3.574

[0577] f2CL=-18.995

[0578] In the optical system OL12, the 15th surface and the 16th surface are formed into aspherical shapes. Table 24 below shows data of the aspherical surface, that is, the values ​​of the cone constant K and the aspherical constants A4 to A10.

[0579] (Table 24)

[0580] [Aspherical surface data]

[0581]

[0582] exist Fig.24 The spherical aberration diagram, astigmatism diagram, distortion diagram, and coma diagram of the optical system OL12 are shown. From these aberration diagrams, it can be seen that the optical system OL11 corrects each aberration well.

[0583] Numerical values ​​of conditional expressions (1) to (23) in the first embodiment (optical system OL1 ) to the twelfth embodiment (optical system OL12 ) are described below.

[0584] (1)ωmax

[0585] (2)(-f1) / θmax

[0586] (3)D12 / (-f1)

[0587] (4) (Lnr1-Lpr2) / (Lnr1+Lpr2)

[0588] (5)(-f1) / f2

[0589] (6)Dn / f

[0590] (7)Dn / (-f1)

[0591] (8)(-f1) / f

[0592] (9)f2 / f

[0593] (10)D12 / (-f11)

[0594] (11)DS / (-f1)

[0595] (12)DS / (-f11)

[0596] (13) (L1r2-L1r1) / (L1r2+L1r1)

[0597] (14)TL / f

[0598] (15)BF / f

[0599] (16)ΣD1 / f

[0600] (17)ΣD2 / f

[0601] (18)(-f1ne) / f

[0602] (19)f22 / f

[0603] (20)f2CL / (-f1)

[0604] (21)(-f1ne) / θmax

[0605] (22) νda

[0606] (23)(L3r1-L2r2) / (L3r1+L2r2)

[0607]

[0608]

[0609]

[0610]

[0611] Description of labels:

[0612] 1 Camera (optical equipment) OL (OL1~OL12) optical system

[0613] G11st lens group G22nd lens group

[0614] L1n1, L1n2, L1n3 negative lenses

[0615] L1p1 positive lens L1nr rear negative lens

Claims

1. An optical system, wherein: The lens is composed of, in order from the object side, a first lens group having negative refractive power, an aperture stop, and a second lens group having positive refractive power; The first lens group is composed of two negative lenses, a positive lens, and a rear negative lens in order from the object side, and the second lens group is composed of a positive lens, a cemented lens formed by cementing a positive lens and a negative lens, and a positive lens in order from the object side. Alternatively, the first lens group is composed of two negative lenses and a cemented positive lens formed by cementing a positive lens and a rear negative lens in order from the object side, and the second lens group is composed of a positive lens, a cemented negative lens formed by cementing a positive lens and a negative lens in order from the object side, and a positive lens, Alternatively, the first lens group is composed of three negative lenses and a cemented positive lens formed by cementing a positive lens and a rear negative lens in order from the object side, and the second lens group is composed of a positive lens, a cemented negative lens formed by cementing a positive lens and a negative lens in order from the object side, and a positive lens, Alternatively, the first lens group is composed of three negative lenses, a positive lens, and a rear negative lens in order from the object side, and the second lens group is composed of a positive lens, a cemented positive lens formed by cementing a positive lens and a negative lens, and a positive lens in order from the object side, Alternatively, the first lens group is composed of, in order from the object side, two negative lenses, a cemented positive lens formed by cementing a negative lens and a positive lens, and a rear negative lens, and the second lens group is composed of, in order from the object side, a positive lens, a cemented negative lens formed by cementing a positive lens and a negative lens, and a positive lens; All of the negative lenses of the first lens group disposed on the object side relative to the positive lens of the first lens group are meniscus-shaped with a convex surface facing the object side. The lens placed closest to the image side is a single lens. And satisfy the following conditions: 90.00°<ωmax≤110.00° 0.800 <BF / f≤1.849 0.200<(-f1) / f2<4.500 in, ωmax: Maximum value of the half field angle of the optical system [°] BF: back focal length of the optical system f: focal length of the entire system of the optical system f1: focal length of the first lens group f2: focal length of the second lens group.

2. The optical system according to claim 1, wherein: Satisfy the following conditions: 0.130 <Dn / f<3.500 in, Dn: The thickness on the optical axis of the negative lens disposed most on the image side among the negative lenses included in the first lens group f: The focal length of the entire optical system.

3. The optical system according to claim 1, wherein: Satisfy the following conditions: 0.100 <D12 / (-f11)<0.500 in, D12: The distance on the optical axis between the two negative lenses of the first lens group disposed closest to the object side f11: The focal length of the negative lens of the first lens group disposed most on the object side.

4. The optical system according to claim 1, wherein: Satisfy the following conditions: -10.000<(Lnr1-Lpr2) / (Lnr1+Lpr2)≤0.000 in, Lpr2: The radius of curvature of the image side lens surface of the positive lens Lnr1: The radius of curvature of the object-side lens surface of the rear negative lens.

5. The optical system according to claim 1, wherein: Satisfy the following conditions: 0.020 <Dn / (-f1)<1.500 in, Dn: The thickness on the optical axis of the negative lens disposed most on the image side among the negative lenses included in the first lens group f1: focal length of the first lens group.

6. The optical system according to claim 1, wherein: Satisfy the following conditions: 1.000<(-f1) / f<7.000 in, f1: focal length of the first lens group f: The focal length of the entire optical system.

7. The optical system according to claim 1, wherein: Satisfy the following conditions: 2.500 <f2 / f<4.500 in, f2: focal length of the second lens group f: The focal length of the entire optical system.

8. The optical system according to claim 1, wherein: Satisfy the following conditions: 0.015 <DS / (-f1)<1.500 in, DS: The distance on the optical axis from the lens surface of the first lens group closest to the image side to the lens surface of the second lens group closest to the object side f1: focal length of the first lens group.

9. The optical system according to claim 1, wherein: Satisfy the following conditions: 0.005 <DS / (-f11)<0.250 in, DS: The distance on the optical axis from the lens surface of the first lens group closest to the image side to the lens surface of the second lens group closest to the object side f11: The focal length of the negative lens of the first lens group disposed most on the object side.

10. The optical system according to claim 1, wherein: Satisfy the following conditions: -1.000<(L1r2-L1r1) / (L1r2+L1r1)<-0.250 in, L1r1: The radius of curvature of the object-side lens surface of the negative lens disposed closest to the object side in the first lens group L1r2: The curvature radius of the image-side lens surface of the negative lens disposed most on the object side in the first lens group.

11. The optical system according to claim 1, wherein: Satisfy the following conditions: 8.500 <TL / f<21.000 in, TL: total length of the optical system f: The focal length of the entire optical system.

12. The optical system according to claim 1, wherein: Satisfy the following conditions: 5.000<ΣD1 / f<13.000 in, ΣD1: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the first lens group f: The focal length of the entire optical system.

13. The optical system according to claim 1, wherein: Satisfy the following conditions: 2.800<ΣD2 / f<8.200 in, ΣD2: The distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the second lens group f: The focal length of the entire optical system.

14. The optical system according to claim 1, wherein: Satisfy the following conditions: 1.000<(-f1ne) / f<3.000 in, f1ne: The composite focal length of the negative lens of the first lens group arranged on the object side relative to the positive lens f: The focal length of the entire optical system.

15. The optical system of claim 1, wherein: Satisfy the following conditions: 1.200 <f22 / f<4.100 in, f22: The focal length of the biconvex positive lens of the cemented lens included in the second lens group, which is located closest to the object and is formed by cementing a biconvex positive lens and a biconcave negative lens. f: The focal length of the entire optical system.

16. The optical system of claim 1, wherein: Satisfy the following conditions: -8.000 <f2CL / (-f1)<90.000 in, f2CL: The focal length of the cemented lens disposed closest to the object among the cemented lenses included in the second lens group f1: focal length of the first lens group.

17. The optical system of claim 1, wherein: Satisfy the following conditions: 0.500<(-f1ne) / θmax<4.500 in, f1ne: The composite focal length of the negative lens of the first lens group arranged on the object side relative to the positive lens [mm] θmax: The maximum value of the half field angle of the optical system [radians].

18. The optical system of claim 1, wherein: Satisfy the following conditions: 32.000<νda<70.000 in, νda: average value of the Abbe numbers of the medium of the negative lens of the first lens group arranged on the object side with respect to the positive lens for d-line.

19. The optical system of claim 1, wherein: Satisfy the following conditions: 0.250<(L3r1-L2r2) / (L3r1+L2r2)<1.500 in, L2r2: The curvature radius of the image side lens surface of the second lens arranged from the object side in the first lens group L3r1: The curvature radius of the object-side lens surface of the third lens arranged from the object side in the first lens group.

20. An optical device comprising the optical system according to any one of claims 1 to 19.

Images