Optical system, optical device, and method for manufacturing optical system

Abstract

This optical system, comprising a front group, an aperture diaphragm, and a rear group in the stated order from the object side, the front group having at least three negative lenses and at least one positive lens in the stated order from the object side, and the rear group having at least four lenses, is configured so as to satisfy all of the following conditional expressions: 8.90 < ΣT1 / f < 18.00, 2.00 < (-f12) / f > 4.20, and 160.00° < 2ω, where ΣT1 is the thickness of the front group on the optical axis thereof, f is the focal length of the optical system, f12 is the focal length of the lens arranged second from the object side in the front group, and 2ω is the total angle of view of the optical system.

Description

Technical Field

[0001] The present disclosure relates to an optical system, an optical device, and a method for manufacturing an optical system.

Background Art

[0002] Conventionally, optical systems used in optical devices such as photographic cameras, digital still cameras, and video cameras have been proposed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The optical system of the present disclosure includes, in order from the object side, a front group, an aperture stop, and a rear group. The front group has at least three negative lenses and at least one positive lens in order from the object side, and the rear group has at least four lenses, and both of the following conditional expressions are satisfied. 8.90 < ΣT1 / f < 18.00 2.00 < (-f12) / f< 4.20 160.00° < 2ω However, T1: Thickness on the optical axis of the front group f: Focal length of the optical system f12: Focal length of the second lens arranged from the object side in the front group 2ω: Total field angle of the optical system

[0005] The optical system of the present disclosure includes, in order from the object side, a front group, an aperture stop, and a rear group. The front group has at least three negative lenses and at least one positive lens in order from the object side, and the rear group has at least four lenses, and both of the following conditional expressions are satisfied. 1.30 < f / DS < 9.00 0.10 < D112 / (-f1) < 1.22 160.00° < 2ω However, f: Focal length of the optical system DS: Air space on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group D112: Air space on the optical axis between the lens disposed closest to the object side in the front group and the second lens disposed from the object side f1: Focal length of the front group 2ω: Total field angle of the optical system

[0006] The optical system of the present disclosure comprises, in order from the object side, a front group, an aperture stop, and a rear group. The front group has, in order from the object side, at least 3 negative lenses and at least 1 positive lens, and the rear group has at least 4 lenses, and satisfies the following conditional expressions together. 10.00 < TL / f < 27.00 3.00 < f2l / f < 5.40 2.15 < f11 / f12 < 4.00 160.00° < 2ω However, TL: Total length of the optical system f: Focal length of the optical system f2l: Focal length of the lens disposed closest to the image side in the rear group f11: Focal length of the lens disposed closest to the object side in the front group f12: Focal length of the second lens disposed from the object side in the front group 2ω: Total field angle of the optical system

[0007] The manufacturing method of the optical system of the present disclosure is a manufacturing method of an optical system comprising, in order from the object side, a front group, an aperture stop, and a rear group, the front group having, in order from the object side, at least 3 negative lenses and at least 1 positive lens, and the rear group having at least 4 lenses, and arranging each lens so as to satisfy the following conditional expressions together. 8.90 < ΣT1 / f < 18.00 2.00 < (-f12) / f < 4.20 160.00° < 2ω However, T1: Thickness on the optical axis of the front group f: Focal length of the optical system f12: Focal length of the second lens arranged from the object side in the front group 2ω: Total field angle of the optical system

[0008] The manufacturing method of the optical system consists of a front group, a diaphragm, and a rear group in order from the object side. The front group has at least 3 negative lenses and at least 1 positive lens in order from the object side, and the rear group has at least 4 lenses. It is a manufacturing method of an optical system in which each lens is arranged so as to satisfy the following conditional expressions together. 1.30 < f / DS < 9.00 0.10 < D112 / (-f1) < 1.22 160.00° < 2ω However, f: Focal length of the optical system DS: Air gap on the optical axis between the lens arranged most on the image side in the front group and the lens arranged most on the object side in the rear group D112: Air gap on the optical axis between the lens arranged most on the object side in the front group and the second lens arranged from the object side f1: Focal length of the front group 2ω: Total field angle of the optical system

[0009] The manufacturing method of the optical system consists of a front group, a diaphragm, and a rear group in order from the object side. The front group has at least 3 negative lenses and at least 1 positive lens in order from the object side, and the rear group has at least 4 lenses. It is a manufacturing method of an optical system in which each lens is arranged so as to satisfy the following conditional expressions together. 10.00 < TL / f < 27.00 There is 3.00 < f2l / f < 5.40 2.15 < f11 / f12 < 4.00 160.00° < 2ω However, TL: Total length of the optical system f: Focal length of the optical system f2l: Focal length of the lens disposed closest to the image side in the rear group f11: Focal length of the lens disposed closest to the object side in the front group f12: Focal length of the second lens disposed from the object side in the front group 2ω: Total field angle of the optical system

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] Hereinafter, the optical system, the optical device, and the method for manufacturing the optical system according to the embodiments of the present application will be described.

[0012] The optical system of the present embodiment consists of a front group, an aperture stop, and a rear group in order from the object side. The front group has at least three negative lenses and at least one positive lens in order from the object side. The rear group has at least four lenses and satisfies the following conditional expressions (1) 8.90 < ΣT1 / f < 18.00 (2) 2.00 < (-f12) / f< 4.20 (3) 160.00° < 2ω However, ΣT1: The thickness on the optical axis of the front group f: The focal length of the optical system f12: The focal length of the second lens arranged from the object side in the front group 2ω: The total field angle of the optical system

[0013] By having a front group having at least three negative lenses and at least one positive lens in order from the object side and a rear group having at least four lenses, the optical system of the present embodiment can realize an optical system with good correction of chromatic aberration, astigmatism, distortion aberration, coma aberration, and spherical aberration.

[0014] Conditional expression (I) defines the ratio of the thickness on the optical axis of the front group to the focal length of the entire optical system. By satisfying conditional expression (I), the optical system of the present embodiment can appropriately correct various aberrations such as distortion aberration, field curvature, spherical aberration, and coma aberration while suppressing an increase in the overall length of the optical system.

[0015] When the value of conditional expression (I) exceeds the upper limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as distortion aberration and field curvature.

[0016] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (1) to 18.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (1) to 17.00, 16.00, 15.00, 14.00, 13.00, and further 12.50.

[0017] Also, in the optical system of the present embodiment, when the value of the conditional expression (1) is less than the lower limit value, it becomes difficult to appropriately correct various aberrations such as spherical aberration, coma aberration, and field curvature.

[0018] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (1) to 8.90, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (1) to 8.92, 8.94, 8.96, 8.98, and further 9.00.

[0019] The conditional expression (2) defines the ratio of the focal length of the second lens arranged from the object side in the front group to the focal length of the entire optical system. By satisfying the conditional expression (2), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature and astigmatism while suppressing an increase in the diameter of the lens arranged closest to the object side.

[0020] In the optical system of the present embodiment, when the value of the conditional expression (2) exceeds the upper limit value, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0021] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (2) to 4.20, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (2) to 4.16, 4.12, 4.08, 4.04, and further 4.00.

[0022] Also, in the optical system of the present embodiment, when the value of conditional expression (2) is lower than the lower limit value, the power of the second lens arranged from the object side of the front group becomes stronger, and it becomes necessary to increase the diameter in order to weaken the power of the lens arranged most on the object side of the front group for aberration correction.

[0023] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (2) to 2.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (2) to 2.16, 2.32, 2.48, 2.64, and further 2.80.

[0024] Conditional expression (3) defines the total angle of view of the optical system. The optical system of the present embodiment can be made an ultra-wide-angle lens by satisfying conditional expression (3).

[0025] An optical system that satisfies all of conditional expression (1), conditional expression (2), and conditional expression (3) is an ultra-wide-angle lens, and while suppressing an increase in the overall length of the optical system and the diameter of the lens on the most object side, various aberrations can be appropriately corrected.

[0026] The optical system of the present embodiment preferably satisfies the following conditional expression. (4) 0.10 < D112 / (-f1) < 1.22 However, D112: The air interval on the optical axis between the lens arranged most on the object side and the second lens arranged from the object side in the front group f1: The focal length of the front group

[0027] Conditional expression (4) defines the ratio of the air interval on the optical axis between the lens arranged most on the object side and the second lens arranged from the object side in the front group to the focal length of the front group. The optical system of the present embodiment can appropriately correct various aberrations such as field curvature, coma aberration, and longitudinal chromatic aberration while suppressing an increase in the overall length of the optical system by satisfying conditional expression (4).

[0028] In the optical system of this embodiment, when the value of conditional expression (4) exceeds the upper limit value, the overall length of the optical system increases, making it difficult to appropriately correct various aberrations such as field curvature, coma aberration, and chromatic aberration of magnification.

[0029] In the optical system of this embodiment, by setting the upper limit value of conditional expression (4) to 1.22, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (4) to 1.17, 1.11, 1.06, 1.00, and further 0.95.

[0030] Also, in the optical system of this embodiment, when the value of conditional expression (4) is below the lower limit value, the overall length of the optical system becomes large, making it difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0031] In the optical system of this embodiment, by setting the lower limit value of conditional expression (4) to 0.10, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the lower limit value of conditional expression (4) to 0.70, 1.40, 2.00, 2.70, and further 3.30.

[0032] The optical system of this embodiment comprises, in order from the object side, a front group, an aperture stop, and a rear group. The front group has, in order from the object side, at least 3 negative lenses and at least 1 positive lens. The rear group has at least 4 lenses and satisfies both of the following conditional expressions (5) 1.30 < f / DS < 9.00 (4) 0.10 < D112 / (-f1) < 1.22 (3) 160.00° < 2ω However, f: Focal length of the optical system DS: Axial air gap between the lens disposed most on the image side in the front group and the lens disposed most on the object side in the rear group D112: Axial air gap between the lens disposed most on the object side in the front group and the second lens disposed from the object side f1: Focal length of the front group 2ω: Total angular field of the optical system

[0033] Conditional expression (5) defines the ratio between the focal length of the entire optical system and the air gap on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group. By satisfying conditional expression (5), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the overall length of the optical system.

[0034] When the value of conditional expression (5) exceeds the upper limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0035] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (5) to 9.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (5) to 8.70, 8.50, 8.20, 7.80, and further 7.60.

[0036] Further, when the value of conditional expression (5) is below the lower limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0037] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (5) to 1.30, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (5) to 1.70, 2.20, 2.60, 3.10, and further 3.50.

[0038] An optical system that satisfies conditional expression (5), conditional expression (4), and conditional expression (3) is an ultra-wide-angle lens, and can appropriately correct various aberrations while suppressing an increase in the overall length of the optical system.

[0039] Further, the optical system of the present embodiment preferably satisfies the following expression. (6) 0.50 < f2l / f2 < 3.00 However, f2l: Focal length of the lens disposed closest to the image side in the rear group f2: Focal length of the rear group

[0040] Conditional expression (6) defines the ratio between the focal length of the lens disposed closest to the image side in the rear group and the focal length of the rear group. By satisfying conditional expression (6), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature, astigmatism, spherical aberration, and coma aberration while suppressing an increase in the overall length of the optical system.

[0041] If the value of conditional expression (6) exceeds the upper limit value in the optical system of the present embodiment, the power of the lens disposed closest to the image side becomes weak, and it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0042] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (6) to 3.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (6) to 2.70, 2.30, 2.00, 1.70, and further 1.36.

[0043] Also, if the value of conditional expression (6) is below the lower limit value in the optical system of the present embodiment, the power of the entire rear group becomes weak, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0044] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (6) to 0.50, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (6) to 0.55, 0.60, 0.70, 0.75, and further 0.80.

[0045] Also, the optical system of the present embodiment preferably satisfies the following conditional expression. (7) 10.00 < TL / f < 27.00 However, TL: Total length of the optical system in terms of air equivalent length

[0046] Conditional expression (7) defines the ratio of the total length of the optical system in terms of air equivalent length to the focal length of the entire optical system. By satisfying conditional expression (7), the optical system of this embodiment can appropriately correct various aberrations such as field curvature, spherical aberration, coma aberration, and distortion aberration while suppressing an increase in the total length of the optical system.

[0047] When the value of conditional expression (7) exceeds the upper limit value in the optical system of this embodiment, the total length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature, spherical aberration, and coma aberration.

[0048] In the optical system of this embodiment, by setting the upper limit value of conditional expression (7) to 27.00, the effects of this embodiment can be made more certain. Also, in order to make the effects of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (7) to 26.00, 25.00, 23.50, 22.50, and further 21.50.

[0049] Also, when the value of conditional expression (7) is below the lower limit value in the optical system of this embodiment, it becomes difficult to appropriately correct various aberrations such as distortion aberration, field curvature, and spherical aberration.

[0050] In the optical system of this embodiment, by setting the lower limit value of conditional expression (7) to 10.00, the effects of this embodiment can be made more certain. Also, in order to make the effects of this embodiment more certain, it is preferable to set the lower limit value of conditional expression (7) to 11.00, 12.00, 13.00, 14.00, and further 15.00.

[0051] Also, the optical system of this embodiment preferably satisfies the following conditional expression. (8) 3.00 < f2l / f < 5.40 However, f2l: Focal length of the lens arranged closest to the image side in the rear group

[0052] Conditional expression (8) defines the ratio between the focal length of the lens disposed most image-side in the rear group and the focal length of the entire optical system. By satisfying conditional expression (8), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature and astigmatism while suppressing an increase in the overall length of the optical system.

[0053] In the optical system of the present embodiment, when the value of conditional expression (8) exceeds the upper limit value, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0054] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (8) to 5.40, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (8) to 5.25, 5.10, 5.00, 4.85, and further 4.70.

[0055] Also, in the optical system of the present embodiment, when the value of conditional expression (8) is less than the lower limit value, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0056] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (8) to 3.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (8) to 3.06, 3.12, 3.18, 3.24, and further 3.30.

[0057] The optical system of the present embodiment includes, in order from the object side, a front group, an aperture stop, and a rear group. The front group has, in order from the object side, at least three negative lenses and at least one positive lens. The rear group has at least four lenses and satisfies both of the following conditional expressions (7) 10.00 < TL / f < 27.00 (8) 3.00 < f2l / f < 5.40 (9) 2.15 < f11 / f12 < 4.00 (3) 160.00° < 2ω However, TL: Total length of the optical system in terms of the air equivalent length f: Focal length of the optical system f2l: Focal length of the lens disposed closest to the image side in the rear group f11: Focal length of the lens disposed closest to the object side in the front group f12: Focal length of the second lens disposed from the object side in the front group 2ω: Total field angle of the optical system

[0058] Conditional expression (9) defines the ratio between the focal length of the lens disposed closest to the object side in the front group and the focal length of the second lens disposed from the object side in the front group. By satisfying conditional expression (9), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature, spherical aberration, and distortion while suppressing an increase in the diameter of the lens disposed closest to the object side in the front group.

[0059] When the value of conditional expression (9) exceeds the upper limit value in the optical system of the present embodiment, the diameter of the lens disposed closest to the object side in the front group increases, making it difficult to appropriately correct various aberrations such as field curvature, spherical aberration, and distortion.

[0060] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (9) to 4.00, the effects of the present embodiment can be made more reliable. Further, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (9) to 3.85, 3.70, 3.50, 3.35, and further to 3.20.

[0061] Also, when the value of conditional expression (9) is below the lower limit value in the optical system of the present embodiment, the diameter of the lens disposed closest to the object side in the front group becomes large, making it difficult to appropriately correct various aberrations such as field curvature, spherical aberration, and distortion.

[0062] In the optical system of this embodiment, by setting the lower limit value of conditional expression (9) to 2.15, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the lower limit value of conditional expression (9) to 2.18, 2.20, 2.25, 2.28, and further 2.30.

[0063] An optical system that satisfies conditional expressions (7), (8), (9), and (3) is an ultra-wide-angle lens, and while suppressing an increase in the overall length of the optical system and the diameter of the lens disposed on the most object side, various aberrations can be appropriately corrected.

[0064] Further, the optical system of this embodiment preferably satisfies the following conditional expressions. (10) -3.00 < (r2+r1) / (r2-r1) < -2.00 However, r1: The radius of curvature of the object-side surface of the lens disposed on the most object side in the front group r2: The radius of curvature of the image-side surface of the lens disposed on the most object side in the front group

[0065] Conditional expression (10) defines the shape factor of the lens disposed on the most object side in the front group. By satisfying conditional expression (10), the optical system of this embodiment can appropriately correct various aberrations such as field curvature, astigmatism, and coma aberration.

[0066] When the value of conditional expression (10) exceeds the upper limit value in the optical system of this embodiment, it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0067] In the optical system of this embodiment, by setting the upper limit value of conditional expression (10) to -2.00, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (10) to -2.05, -2.10, -2.20, -2.25, and further 2.30.

[0068] In addition, in the optical system of the present embodiment, when the value of conditional expression (10) is lower than the lower limit value, it becomes difficult to appropriately correct various aberrations such as field curvature, astigmatism, and coma aberration.

[0069] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (10) to -3.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (10) to -2.95, -2.90, -2.85, and further -2.80.

[0070] In addition, the optical system of the present embodiment preferably satisfies the following conditional expression. (11) 3.00 < ΣT2 / f < 7.00 However, ΣT2: Thickness on the optical axis of the rear group

[0071] Conditional expression (11) defines the ratio of the thickness on the optical axis of the rear group to the focal length of the entire optical system. By satisfying conditional expression (11), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration, coma aberration, field curvature, and chromatic aberration of magnification while suppressing an increase in the overall length of the optical system.

[0072] When the value of conditional expression (11) exceeds the upper limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0073] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (11) to 7.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (11) to 6.90, 6.80, 6.65, 6.50, and further 6.40.

[0074] In addition, when the value of conditional expression (11) is lower than the lower limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as field curvature, coma aberration, and chromatic aberration of magnification.

[0075] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (11) to 3.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (11) to 3.25, 3.50, 3.80, 4.00, and further 4.30.

[0076] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (12) 1.00 < (-f1) / f < 25.00 However, f1: Focal length of the front group

[0077] The conditional expression (12) defines the ratio of the focal length of the front group to the focal length of the entire optical system. By satisfying the conditional expression (12), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature, astigmatism, spherical aberration, and coma aberration while suppressing an increase in the diameter of the lens disposed closest to the object side in the front group.

[0078] When the value of the conditional expression (12) exceeds the upper limit value in the optical system of the present embodiment, the power of the lens disposed closest to the object side in the front group becomes weak and the diameter increases, making it difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0079] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (12) to 25.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (12) to 24.50, 24.00, 23.50, and further 23.00.

[0080] Further, when the value of the conditional expression (12) is less than the lower limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0081] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (12) to 1.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (12) to 1.40, 1.75, 2.20, 2.50, and further 2.90.

[0082] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (13) 2.70 < f2 / f < 4.8 However, f2: Focal length of the rear group

[0083] Conditional expression (13) defines the ratio of the focal length of the rear group to the focal length of the entire optical system. By satisfying conditional expression (13), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration, coma aberration, field curvature, and chromatic aberration of magnification while suppressing an increase in the overall length of the optical system.

[0084] When the value of conditional expression (13) exceeds the upper limit value in the optical system of the present embodiment, the power of the rear group becomes weak, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration. [[ID=!19]]

[0085] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (13) to 4.80, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (13) to 4.70, 4.60, 4.50, 4.40, and further 4.30.

[0086] Further, when the value of conditional expression (13) is less than the lower limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as field curvature, coma aberration, and chromatic aberration of magnification.

[0087] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (13) to 2.70, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (13) to 2.78, 2.85, 2.95, 3.00, and further 3.10.

[0088] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (14) 0.45 < (-f1) / f2 < 6.00 However, f1: Focal length of the front group f2: Focal length of the rear group

[0089] The conditional expression (14) defines the ratio of the focal length of the front group to the focal length of the rear group. By satisfying the conditional expression (14), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the diameter of the lens disposed closest to the object side in the front group.

[0090] When the value of the conditional expression (14) exceeds the upper limit value in the optical system of the present embodiment, the power of the front group becomes weaker than that of the rear group, so the diameter of the lens disposed closest to the object side in the front group increases, and the spherical aberration deteriorates because the power of the rear group becomes stronger.

[0091] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (14) to 6.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (14) to 5.60, 5.20, 4.80, 4.40, and further 4.00.

[0092] Further, when the value of the conditional expression (14) is below the lower limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0093] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (14) to 0.45, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (14) to 0.50, 0.55, 0.60, 0.65, and further 0.70.

[0094] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (15) 1.50 < D112 / f < 4.50 However, D112: The air interval on the optical axis between the lens disposed closest to the object side in the front group and the second lens disposed from the object side.

[0095] The conditional expression (15) defines the ratio of the air interval on the optical axis between the lens disposed closest to the object side in the front group and the second lens disposed from the object side to the focal length of the optical system. By satisfying the conditional expression (15), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature, spherical aberration, coma aberration, and distortion aberration while suppressing an increase in the overall length of the optical system.

[0096] When the value of the conditional expression (15) exceeds the upper limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as field curvature, spherical aberration, and coma aberration.

[0097] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (15) to 4.50, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (15) to 4.25, 4.00, 3.70, 3.45, and further 3.20.

[0098] Further, when the value of the conditional expression (15) is below the lower limit value in the optical system of the present embodiment, it becomes difficult to appropriately correct various aberrations such as distortion aberration, field curvature, and spherical aberration.

[0099] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (15) to 1.50, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (15) to 1.65, 1.80, 2.00, 2.15, and further 2.30.

[0100] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (16) 0.005 < DS / (-f1) < 0.700 However, DS: The air interval on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group f1: The focal length of the front group

[0101] The conditional expression (16) defines the ratio of the air interval on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group to the focal length of the front group. By satisfying the conditional expression (16), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the overall length of the optical system.

[0102] When the value of the conditional expression (16) exceeds the upper limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0103] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (16) to 0.70, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (16) to 0.68, 0.66, 0.64, 0.62, and further 0.60.

[0104] Further, when the value of the conditional expression (16) is below the lower limit value in the optical system of the present embodiment, the overall length of the optical system increases, and it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0105] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (16) to 1.50, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (16) to 1.65, 1.80, 2.00, 2.15, and further 2.30.

[0106] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (17) 0.20 < (-f112) / f2 < 1.00 However, f112: The combined focal length of the lens disposed closest to the object side in the front group and the second lens disposed from the object side. f2: The focal length of the rear group.

[0107] The conditional expression (17) defines the ratio of the combined focal point of the lens disposed closest to the object side in the front group and the second lens disposed from the object side to the focal length of the rear group. By satisfying the conditional expression (17), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the overall length of the optical system and the diameter of the lens disposed closest to the object side in the front group.

[0108] When the value of the conditional expression (17) exceeds the upper limit value in the optical system of the present embodiment, the power of the front group becomes weaker than that of the rear group, so the diameter of the lens disposed closest to the object side in the front group increases, and the power of the rear group becomes stronger, resulting in deterioration of spherical aberration.

[0109] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (17) to 1.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (17) to 0.95, 0.90, 0.80, 0.75, and further 0.70.

[0110] In addition, in the optical system of the present embodiment, when the value of conditional expression (17) is less than the lower limit value, the power of the rear group becomes weak, so the overall optical length increases, making it difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0111] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (17) to 0.20, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (17) to 0.24, 0.28, 0.32, 0.36, and further 0.40.

[0112] In addition, the optical system of the present embodiment preferably satisfies the following conditional expression. (18) 1.10 < (-f11) / f2l < 4.00 However, f11: Focal length of the lens disposed closest to the object side in the front group f2l: Focal length of the lens disposed closest to the image side in the rear group

[0113] Conditional expression (18) defines the ratio of the focal length of the lens disposed closest to the object side in the front group to the focal length of the lens disposed closest to the image side in the rear group. By satisfying conditional expression (18), the optical system of the present embodiment can appropriately correct various aberrations such as spherical aberration and coma aberration while suppressing an increase in the diameter of the lens disposed closest to the object side in the front group.

[0114] In the optical system of the present embodiment, when the value of conditional expression (18) exceeds the upper limit value, the power of the front group becomes weaker than that of the rear group, so the diameter of the lens disposed closest to the object side in the front group increases, and the spherical aberration deteriorates because the power of the rear group becomes stronger.

[0115] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (18) to 4.00, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (18) to 3.85, 3.70, 3.50, 3.35, and further 3.20.

[0116] In addition, in the optical system of the present embodiment, when the value of conditional expression (18) is less than the lower limit value, it becomes difficult to appropriately correct various aberrations such as spherical aberration and coma aberration.

[0117] In the optical system of the present embodiment, by setting the lower limit value of conditional expression (18) to 1.10, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of conditional expression (18) to 1.45, 1.80, 2.10, 2.45, and further 2.80.

[0118] In addition, the optical system of the present embodiment preferably satisfies the following conditional expression. (19) 1.85 < nd1 < 2.20 However, nd1: Refractive index based on the d-line of the lens disposed closest to the object side in the front group

[0119] Conditional expression (19) defines the refractive index based on the d-line of the lens disposed closest to the object side in the front group. The optical system of the present embodiment can appropriately correct field curvature by satisfying conditional expression (19).

[0120] When the value of conditional expression (19) exceeds the upper limit value in the optical system of the present embodiment, the power of the lens disposed closest to the object side in the front group becomes strong, and it becomes difficult to appropriately correct field curvature.

[0121] In the optical system of the present embodiment, by setting the upper limit value of conditional expression (19) to 2.20, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of conditional expression (19) to 2.15, 2.10, 2.05, and further 1.95.

[0122] In addition, when the value of conditional expression (19) is less than the lower limit value in the optical system of the present embodiment, the power of the lens disposed closest to the object side in the front group becomes weak, and it becomes difficult to appropriately correct field curvature.

[0123] In the optical system of this embodiment, by setting the lower limit value of the conditional expression (19) to 1.85, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (19) to 1.87, 1.89, 1.91, 1.93, and further 1.95.

[0124] Further, the optical system of this embodiment preferably satisfies the following conditional expression. (20) 1.50 < nd2 < 1.95 However, nd2: Refractive index based on the d-line of the lens arranged second from the object side in the front group

[0125] The conditional expression (20) defines the refractive index based on the d-line of the lens arranged second from the object side in the front group. By satisfying the conditional expression (20), the optical system of this embodiment can appropriately correct the field curvature.

[0126] When the value of the conditional expression (20) exceeds the upper limit value in the optical system of this embodiment, the power of the lens arranged second from the object side in the front group becomes strong, and it becomes difficult to appropriately correct the field curvature.

[0127] In the optical system of this embodiment, by setting the upper limit value of the conditional expression (20) to 1.95, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the upper limit value of the conditional expression (20) to 1.90, 1.85, 1.80, 1.75, and further 1.70.

[0128] Also, when the value of the conditional expression (20) is below the lower limit value in the optical system of this embodiment, the power of the lens arranged second from the object side in the front group becomes weak, and it becomes difficult to appropriately correct the field curvature.

[0129] In the optical system of the present embodiment, by setting the lower limit value of the conditional expression (20) to 1.50, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the lower limit value of the conditional expression (20) to 1.51, 1.52, and further 1.53.

[0130] Further, the optical system of the present embodiment preferably satisfies the following conditional expression. (21) 1.45 < nd3 < 1.90 However, nd3: The refractive index based on the d-line of the lens disposed closest to the image side in the rear group

[0131] The conditional expression (21) defines the refractive index based on the d-line of the lens disposed closest to the image side in the rear group. By satisfying the conditional expression (21), the optical system of the present embodiment can appropriately correct various aberrations such as field curvature and astigmatism.

[0132] When the value of the conditional expression (21) exceeds the upper limit value in the optical system of the present embodiment, the power of the lens disposed closest to the image side in the rear group becomes strong, and it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0133] In the optical system of the present embodiment, by setting the upper limit value of the conditional expression (21) to 1.90, the effects of the present embodiment can be made more certain. Further, in order to make the effects of the present embodiment more certain, it is preferable to set the upper limit value of the conditional expression (21) to 1.85, 1.80, 1.75, and further 1.70.

[0134] Also, when the value of the conditional expression (21) is below the lower limit value in the optical system of the present embodiment, the power of the lens disposed closest to the image side in the rear group becomes weak, and it becomes difficult to appropriately correct various aberrations such as field curvature and astigmatism.

[0135] In the optical system of this embodiment, by setting the lower limit value of the conditional expression (21) to 1.45, the effects of this embodiment can be made more certain. Further, in order to make the effects of this embodiment more certain, it is preferable to set the lower limit value of the conditional expression (21) to 1.46, 1.47, 1.48, and further to 1.49.

[0136] With the above configuration, an optical system having a small size and good imaging performance can be realized.

[0137] The optical device of this embodiment has an optical system with the above-described configuration. Thereby, an optical device having a small size and good optical performance can be realized.

[0138] The manufacturing method of the optical system of this embodiment is a manufacturing method of an optical system including, in order from the object side, a front group, an aperture stop, and a rear group, wherein the front group has at least 3 negative lenses and at least 1 positive lens in order from the object side, and the rear group has at least 4 lenses, and each lens is arranged so as to satisfy the following conditional expressions. (1) 8.90 < ΣT1 / f < 18.00 (2) 2.00 < (-f12) / f< 4.20 (3) 160.00° < 2ω However, ΣT1: Thickness on the optical axis of the front group f: Focal length of the optical system f12: Focal length of the second lens arranged from the object side in the front group 2ω: Total field angle of the optical system

[0139] The manufacturing method of the optical system of this embodiment is a manufacturing method of an optical system including, in order from the object side, a front group, an aperture stop, and a rear group, wherein the front group has at least 3 negative lenses and at least 1 positive lens in order from the object side, and the rear group has at least 4 lenses, and each lens is arranged so as to satisfy the following conditional expressions. (5) 1.30 < f / DS < 9.00 (4) 0.10 < D112 / (-f1) < 1.22 (3) 160.00° < 2ω However, f: Focal length of the optical system DS: Air space on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group D112: Air space on the optical axis between the lens disposed closest to the object side in the front group and the second lens disposed from the object side f1: Focal length of the front group 2ω: Total field angle of the optical system

[0140] The manufacturing method of the optical system of this embodiment consists of, in order from the object side, a front group, an aperture stop, and a rear group. The front group has, in order from the object side, at least 3 negative lenses and at least 1 positive lens, and the rear group has at least 4 lenses. It is a manufacturing method of an optical system in which each lens is arranged so as to satisfy the following conditional expressions. (7) 10.00 < TL / f < 27.00 (8) 3.00 < f2l / f < 5.40 (9) 2.15 < f11 / f12 < 4.00 (3) 160.00° < 2ω However, TL: Total length of the entire optical system in terms of air equivalent length f: Focal length of the optical system f2l: Focal length of the lens disposed closest to the image side in the rear group f11: Focal length of the lens disposed closest to the object side in the front group f12: Focal length of the second lens disposed from the object side in the front group 2ω: Total field angle of the optical system

[0141] By such a manufacturing method of an optical system, an optical system having a small size and good optical performance can be manufactured.

[0142] (Numerical Examples) Hereinafter, examples of the present application will be described with reference to the drawings.

[0143] (First Embodiment) FIG. 1 is a cross-sectional view of the optical system according to the first embodiment.

[0144] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0145] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with its convex surface facing the object side, a negative meniscus lens L2 with its convex surface facing the object side, a cemented positive lens composed of a biconcave negative lens L3 and a biconvex positive lens L4, and a negative meniscus lens L5 with its concave surface facing the object side.

[0146] The rear group G2 consists of, in order from the object side, a cemented positive lens composed of a biconvex positive lens L6 and a negative meniscus lens L7 with its concave surface facing the object side, a cemented positive lens composed of a biconvex positive lens L8 and a biconcave negative lens L9, and a biconvex positive lens L10.

[0147] An image pickup device (not shown) composed of a CCD, a CMOS, or the like is disposed on the image plane I.

[0148] [[ID=((23))]]A filter FL is disposed between the optical system of this embodiment and the image plane I.

[0149] The following Table 1 lists the values of the specifications of the optical system of this embodiment.

[0150] In [Overall Specifications] of Table 1, TL represents the overall length of the optical system in terms of air equivalent length, and f represents the focal length of the optical system.

[0151] In [Lens Specifications] of Table 1, m represents the order of the optical surface counted from the object side, r represents the radius of curvature, d represents the surface interval, nd represents the refractive index with respect to the d line (wavelength 587.6 nm), and νd represents the Abbe number with respect to the d line. A radius of curvature r = ∞ indicates a plane. Also, an optical surface marked with "*" indicates an aspherical surface.

[0152] In the [Aspherical Data] of Table 1, m indicates the optical surface corresponding to the aspherical data, K indicates the conic constant, and A4 to A10 indicate the aspherical coefficients.

[0153] The aspherical surface is expressed by the following formula (a), where y is the height in the direction perpendicular to the optical axis, S(y) is the distance (amount of sag) along the optical axis from the tangent plane of the vertex of each aspherical surface at height y to each aspherical surface, r is the radius of curvature (paraxial radius of curvature) of the reference spherical surface, K is the conic constant, and An is the n-th order aspherical coefficient. In each example, the second order aspherical coefficient A2 is 0. Also, "En" is expressed as "×10 -n " indicates.

[0154] (a) 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

[0155] The units of focal length f, radius of curvature r, and other lengths listed in Table 1 are "mm." However, this is not limited to this, as the same optical performance can be obtained even when the optical system is proportionally enlarged or reduced.

[0156] The symbols in Table 1 described above will be used in the same manner in tables of other embodiments described later.

[0157] (Table 1) [Overall specifications] TL 25.06 f 1.47 [Lens specifications] mrd nd νd 1) 17.500 1.400 1.950000 29.37 2) 7.105 4.130 * 3) 8.500 1.000 1.693500 53.20 * 4) 2.126 3.780 5) -5.611 0.600 1.496997 81.61 6) 3.256 2.150 1.755200 27.57 7) -9.807 0.320 8) -4.670 0.900 1.496997 81.61 9) -7.192 0.330 10> ∞ 0.000 (Open aperture) 11) 5.040 1.800 1.622990 58.12 12) -3.000 0.400 1.755200 27.57 13) -35.000 0.150 14) 5.629 1.800 1.618000 63.34 15) -3.049 0.400 1.755200 27.57 16) 25.316 1.470 *17) 5.350 2.300 1.693500 53.20 *18) -20.000 1.000 19) ∞ 0.800 1.516800 63.88 20) ∞ 0.607 [Aspherical data] m K A4 A6 A8 A10 3) 1.0000 -3.38E-03 1.51E-04 -4.14E-06 4.51E-08 4) -1.6954 2.11E-02 -3.02E-03 4.08E-04 -2.08E-05 17) 1.0000 -4.43E-03 1.16E-04 -1.44E-04 1.14E-05 18) 1.0000 3.24E-03 -9.31E-04 1.45E-06 5.40E-06 [Focal length data for each group] Group Starting surface Focal length G1 1 -4.41 G2 11 5.04

[0158] Figure 2 is a diagram of various aberrations of the optical system of the first embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberration fluctuations and has high optical performance.

[0159] (Second Embodiment) Figure 3 is a cross-sectional view of the optical system of the second embodiment.

[0160] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0161] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a convex surface facing the object side, a positive meniscus lens L4 with a concave surface facing the object side, and a cemented positive lens composed of a negative meniscus lens L5 with a concave surface facing the object side.

[0162] The rear group G2 consists of, in order from the object side, a biconvex positive lens L6, a biconvex positive lens L7 a cemented negative lens composed of a biconcave negative lens L8, and a biconvex positive lens L9.

[0163] On the image plane I, an image sensor (not shown) composed of a CCD or CMOS, etc. is arranged.

[0164] A filter FL is arranged between the optical system of this embodiment and the image plane I.

[0165] The following Table 2 lists the values of the specifications of the optical system of this embodiment.

[0166] (Table 2) [Overall Specifications] TL 25.23 f 1.48 [Lens Specifications] m r d nd νd 1) 16.913 1.500 2.001000 29.12 2) 7.254 4.150 * 3) 7.136 1.000 1.693500 53.20 * 4) 2.326 2.050 5) 7.072 0.300 1.618000 63.34 6) 3.285 1.550 7) -42.977 2.300 1.755200 27.57 8) -3.302 0.500 1.618000 63.34 9) -9.971 2.600 10> ∞ 0.100 (Open aperture) 11) 5.143 1.150 1.497103 81.56 12) -6.668 0.100 13) 5.839 1.550 1.618000 63.34 14) -3.054 0.350 1.755200 27.57 15) 4.209 1.050 16) 5.459 2.200 1.497103 81.56 *17) -5.042 1.000 *18) ∞ 1.000 1.516800 63.88 19) ∞ 1.118 [Aspherical data] m K A4 A6 A8 A10 3) 1.0000 -3.65E-03 1.02E-04 -1.87E-06 1.15E-08 4) 1.0000 1.19E-03 -3.15E-04 7.14E-05 -3.53E-06 16) 1.0000 -3.79E-03 -1.08E-04 -1.15E-04 1.32E-05 17) 1.0000 -5.42E-04 -8.08E-05 -8.13E-05 8.73E-06 [Focus distance data for each group] Group Starting surface Focus distance G1 1 -5.12 G2 11 5.26

[0167] Figure 4 is a diagram of various aberrations of the optical system of the second embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0168] (Third Embodiment) Figure 5 is a cross-sectional view of the optical system of the third embodiment.

[0169] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0170] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a biconcave negative lens L3, a cemented positive lens composed of a biconvex positive lens L'4, and a negative meniscus lens L5 with a concave surface facing the object side.

[0171] The rear group G2 consists of, in order from the object side, a biconvex positive lens L6, a negative meniscus lens L7 with a concave surface facing the object side, a cemented negative lens composed of a biconvex positive lens L8 and a biconcave negative lens L9, and a biconvex positive lens L10.

[0172] On the image plane I, an image sensor (not shown) composed of a CCD or CMOS, etc. is arranged.

[0173] A filter FL is arranged between the optical system of this embodiment and the image plane I.

[0174] The following Table 3 lists the values of the specifications of the optical system of this embodiment.

[0175] (Table 3) [Overall specifications] TL 25.08 f 1.45 [Lens Specifications] m r d nd νd 1) 18.400 1.400 1.950000 29.37 2) 7.317 4.300 * 3) 7.046 1.000 1.693500 53.20 * 4) 2.003 3.650 5) -10.700 0.400 1.496997 81.61 6) 7.811 2.100 1.846660 23.80 7) -7.811 0.600 8) -4.184 1.900 1.744000 44.80 9) -7.257 0.350 10> ∞ 0.000 (Aperture Stop) 11) 6.799 1.400 1.700000 48.10 12) -3.398 0.400 1.846660 23.80 13) -6.862 0.500 14) 8.053 1.500 1.593190 67.90 15) -3.968 0.400 1.846660 23.80 16) 11.500 1.450 *17) 5.123 1.550 1.622625 58.16 *18) -2,001 1.000 19) ∞ 0.800 1.516800 63.88 20) ∞ 0.656 [Aspherical Data] m K A4 A6 A8 A10 3) 1.0000 -3.33E-03 8.24E-05 -1.46E-06 7.74E-09 4) 1.0000 1.78E-02 -1.99E-03 2.16E-04 -9.95E-06 17) 1.0000 -4.24E-03 6.52E-04 -2.92E-04 2.23E-05 18) 1.0000 3.15E-04 7.13E-04 -3.33E-04 2.64E-05 [Focal distance data for each group] Group Starting surface Focal distance G1 1 -4.85 G2 11 5.00

[0176] Figure 6 is a diagram of various aberrations of the optical system of the third embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0177] (Fourth Embodiment) Figure 7 is a cross-sectional view of the optical system of the fourth embodiment.

[0178] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0179] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative lens L3 with a bi-concave shape, a cemented positive lens composed of a positive lens L4 with a bi-convex shape, and a negative meniscus lens L5 with a concave surface facing the object side.

[0180] The rear group G2 consists of, in order from the object side, a cemented positive lens composed of a positive lens L6 with a bi-convex shape and a negative lens L7 with a bi-concave shape, a cemented negative lens composed of a positive lens L8 with a bi-convex shape and a negative lens L9 with a bi-concave shape, and a positive lens L10 with a bi-convex shape.

[0181] On the image plane I, an image sensor (not shown) composed of a CCD or CMOS, etc. is arranged.

[0182] A filter FL is arranged between the optical system of this embodiment and the image plane I.

[0183] Table 4 below lists the specifications of the optical system of this embodiment.

[0184] (Table 4) [Overall specifications] TL 25.23 f 1.51 [Lens specifications] m r d nd νd 1) 18.400 1.400 1.950000 29.37 2) 7.400 3.900 * 3) 7.140 1.000 1.693500 53.20 * 4) 2.455 4.300 5) -6.678 0.400 1.618000 63.34 6) 7.105 2.200 1.846660 23.80 7) -7.054 0.750 8) -3.246 1.550 1.593190 67.90 9) -3.771 0.100 10> ∞ 0.100 (Aperture stop) 11) 5.106 1.600 1.816000 46.59 12) -5.736 0.500 1.846660 23.80 13) 15.919 0.100 14) 7.589 1.500 1.593190 67.90 15) -4.737 0.400 1.846660 23.80 16) 10.218 0.850 *17) 5.843 2.450 1.693500 53.20 *18) -8.229 1.000 19) ∞ 1.000 1.516800 63.88 20) ∞ 0.468 [Aspherical data] m K A4 A6 A8 A10 3) 1.0000 -2.49E-03 5.31E-05 -8.84E-07 3.58E-09 4) 1.0000 1.69E-02 -1.86E-03 1.76E-04 -6.48E-06 17) 1.0000 -4.33E-03 -2.16E-05 -6.32E-05 6.53E-06 18) 1.0000 1.42E-03 2.47E-05 -8.73E-05 9.74E-06 [Focal distance data for each group] Group Starting surface Focal distance G1 1 -21.76 G2 11 5.57

[0185] Figure 8 is the aberration diagram of the optical system of the fourth embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberration fluctuations and has high optical performance.

[0186] (Fifth Embodiment) Figure 9 is a cross-sectional view of the optical system of the fifth embodiment.

[0187] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0188] The front group G1 consists of, in order from the object side, a cemented negative lens formed by a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a concave surface facing the object side, and a positive meniscus lens L4 with a concave surface facing the object side, and a cemented positive lens formed by a negative meniscus lens L5 with a convex surface facing the object side and a biconvex positive lens L6.

[0189] The rear group G2 consists of, in order from the object side, a cemented positive lens formed by a biconvex positive lens L7 and a biconcave negative lens L8, a cemented positive lens formed by a biconvex positive lens L9 and a biconcave negative lens L10, and a biconvex positive lens L11.

[0190] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0191] Between the optical system of this embodiment and the image plane I, a filter FL is disposed.

[0192] Table 5 below lists the specifications of the optical system of this example.

[0193] (Table 5) [Overall specifications] TL 31.80 f 1.48 [Lens specifications] mrd nd νd 1) 19.058 1.500 1.950000 29.37 2) 7.582 4.700 * 3) 7.447 1.000 1.693500 53.20 * 4) 2.298 4.000 5) -7.500 0.500 1.618000 63.34 6) -21.949 2.900 1.784720 25.64 7) -21.053 0.100 8) 22.559 0.700 1.593190 67.90 9) 6.364 3.000 1.784720 25.64 10) -18.365 1.700 11> ∞ 0.100 (aperture stop) 12) 12.000 2.000 1.816000 46.59 13) -5.067 0.600 1.846660 23.80 14) 219.914 0.400 15) 4.980 2.000 1.618000 63.34 16) -10.712 0.600 1.846660 23.80 *17) 6.930 1.300 *18) 4.966 2.500 1.618806 63.86 19) -10.910 1.000 20) ∞ 1.000 1.516800 63.88 21) ∞ 0.537 [Aspherical Data] m K A4 A6 A8 A10 A12 A14 3) 1.0000 -3.08E-03 8.11E-05 -1.40E-06 8.24E-09 4) 1.0000 6.25E-04 -1.97E-04 3.05E-05 -3.74E-07 18) 1.0000 -4.52E-03 -9.83E-05 -2.94E-05 5.92E-07 19) 1.0000 3.36E-04 6.90E-05 -5.38E-05 4.12E-06 [Focal Length Data for Each Group] Group Starting Surface Focal Length G1 1 -33.10 G2 12 6.27

[0194] Figure 10 is a diagram of various aberrations of the optical system of the fifth embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0195] (Sixth Embodiment) Figure 11 is a cross-sectional view of the optical system of the sixth embodiment.

[0196] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0197] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a cemented positive lens composed of a biconcave negative lens L3 and a biconvex positive lens L4, and a negative meniscus lens L5 with a concave surface facing the object side.

[0198] The rear group G2 consists of, in order from the object side, a cemented positive lens of a biconvex positive lens L6 and a biconcave negative lens L7, a cemented negative lens of a biconvex positive lens L8 and a biconcave negative lens L9, and a biconvex positive lens L10.

[0199] An image pickup device (not shown) composed of a CCD, a CMOS, or the like is disposed on the image plane I.

[0200] A filter FL is disposed between the optical system of this embodiment and the image plane I.

[0201] The following Table 6 lists the values of the specifications of the optical system of this embodiment.

[0202] (Table 6) [Overall specifications] TL 25.01 f 1.29 [Lens specifications] m r d nd νd 1) 18.467 1.400 1.950000 29.37 2) 7.406 3.900 * 3) 7.131 1.000 1.693500 53.20 * 4) 2.178 4.300 5) -7.473 0.400 1.618000 63.34 6) 6.152 2.200 1.846660 23.80 7) -8.020 0.500 8) -3.415 1.650 1.593190 67.90 9) -3.867 0.350 10> ∞ 0.000 (Aperture stop) 11) 4.666 1.700 1.816000 46.59 12) -6.100 0.500 1.846660 23.80 13) 15.792 0.100 14) 11.273 1.600 1.593190 67.90 15) -3.000 0.400 1.846660 23.80 16) 22.308 0.850 *17) 7.103 2.050 1.693500 53.20 *18) -4.850 1.000 19) ∞ 1.000 1.516800 63.88 20) ∞ 0.448 [Aspherical Data] m K A4 A6 A8 A10 3) 1.0000 -2.50E-03 5.17E-05 -8.17E-07 2.68E-09 4) 1.0000 1.69E-02 -1.98E-03 1.85E-04 -6.83E-06 17) 1.0000 -5.59E-03 3.50E-04 -1.51E-04 1.40E-05 18) 1.0000 5.01E-03 -1.60E-04 -9.55E-05 1.22E-05 [Focal Length Data for Each Group] Group Starting Surface Focal Length G1 1 -16.60 G2 11 5.23

[0203] Figure 12 is a diagram of various aberrations of the optical system of the sixth embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0204] (Seventh Embodiment) Figure 13 is a cross-sectional view of the optical system of the seventh embodiment.

[0205] The optical system of this embodiment has, in order from the object side, a front group G1 having a negative refractive power, an aperture stop S, and a rear group G2 having a positive refractive power.

[0206] The front group G1 consists of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a convex surface facing the object side, and a biconvex positive lens L4.

[0207] The rear group G2 consists of, in order from the object side, a biconvex positive lens L5, a cemented negative lens formed by a biconvex positive lens L6 and a biconcave negative lens L7, and a biconvex positive lens L8.

[0208] An imaging element (not shown) composed of a CCD, a CMOS, or the like is arranged on the image plane I.

[0209] A filter FL is arranged between the optical system of this embodiment and the image plane I.

[0210] The following Table 7 lists the values of the specifications of the optical system of this embodiment.

[0211] (Table 7) [Overall specifications] TL 25.11 f 1.58 [Lens specifications] m r d nd νd 1) 16.242 1.550 2.001000 29.12 2) 7.470 4.000 * 3) 7.800 1.000 1.693500 53.20 * 4) 2.526 2.640 5) 150.000 0.350 1.603000 65.44 6) 3.308 0.720 7) 11.331 5.160 1.846660 23.80 8) -11.331 0.200 9> ∞ 0.100 (Aperture stop) 10) 6.695 1.750 1.693500 53.20 11) -6.695 0.100 12) 9.627 1.580 1.618000 63.34 13) -3.017 0.350 1.846660 23.80 14) 8.500 1.860 *15) 4.300 1.620 1.553319 71.68 *16) -21.831 1.000 17) ∞ 1.000 1.516800 63.88 18) ∞ 0.466 [Aspherical Data] m K A4 A6 A8 A10 3) 1.0000 -2.37E-03 4.92E-05 -9.48E-07 9.14E-09 4) 1.0000 1.88E-02 -2.00E-03 2.46E-04 -1.20E-05 15) 1.0000 -4.42E-03 -1.33E-04 -9.98E-05 5.00E-06 16) 1.0000 2.93E-04 3.04E-04 -2.09E-04 1.63E-05 [Group Focal Length Data] Group Starting Surface Focal Length G1 1 -5.61 G2 10 5.27

[0212] Figure 14 is a diagram of various aberrations of the optical system of the seventh embodiment. From each aberration diagram, it can be seen that the optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0213] According to each of the above embodiments, an optical system having a small size and good optical performance can be realized.

[0214] The conditional formula corresponding values of each embodiment are shown below.

[0215] TL is the overall length of the optical system in terms of the equivalent air length, f is the focal length of the optical system, and 2ω is the overall angle of view of the optical system. ΣT1 is the thickness on the optical axis of the front group, and f1 is the focal length of the front group. r1 is the radius of curvature of the object-side surface of the lens that is most disposed on the object side in the front group, r2 is the radius of curvature of the image-side surface of the lens that is most disposed on the object side in the front group, and f11 is the focal length of the lens that is most disposed on the object side in the front group. f12 is the focal length of the lens that is disposed second from the object side in the front group. D112 is the air interval on the optical axis between the lens that is most disposed on the object side and the lens that is disposed second from the object side in the front group, and f112 is the combined focal length of the lens that is most disposed on the object side and the lens that is disposed second from the object side in the front group. DS is the air interval on the optical axis between the lens that is most disposed on the image side in the front group and the lens that is most disposed on the object side in the rear group. ΣT2 is the thickness on the optical axis of the rear group, and f2 is the focal length of the rear group. f2l is the focal length of the lens that is most disposed on the image side in the rear group. nd1 is the refractive index based on the d-line of the lens that is most disposed on the object side in the front group, nd2 is the refractive index based on the d-line of the lens that is disposed second from the object side in the front group, and nd3 is the refractive index based on the d-line of the lens that is most disposed on the image side in the rear group.

[0216] [Condition formula corresponding value] Condition formula | Example 1st 2nd 3rd 4th 5th 6th 7th (1) ΣT1 / f : 9.727 9.020 10.586 10.299 12.432 11.909 9.757 (2) -f12 / f : 2.963 3.676 3.029 3.929 3.502 3.825 3.695 (3) 2ω :220.0 220.0 220.0 220.0 220.0 220.0 210.0 (4) D112 / (-f1) : 0.936 0.811 0.887 0.179 0.142 0.235 0.713 (5) f / DS : 4.449 - 4.143 7.525 - 3.683 5.268 (6) f2l / f2 : 1.248 1.077 1.341 0.953 0.933 0.854 1.261 (7) TL / f : 17.072 17.046 17.299 16.762 21.483 19.402 15.885 (8) f2l / f : 4.287 3.829 4.627 3.525 3.951 3.468 4.201 (9) f11 / f12 : 3.074 2.529 3.103 2.349 2.710 2.814 2.596 (10) (r2+r1) / (r2-r1) : -2.367 -2.502 -2.320 -2.346 -2.321 -2.339 -2.703 (11) ΣT2 / f : 5.667 5.000 4.966 4.917 6.351 5.586 4.594 (12) -f1 / f : 3.006 3.456 3.344 14.455 22.364 12.876 3.551 (13) f2 / f : 3.435 3.555 3.451 3.699 4.236 4.058 3.332 (14) -f1 / f2 : 0.875 0.972 0.969 3.908 5.280 3.173 1.066 (15) D112 / f : 2.813 2.804 2.966 2.591 3.176 3.026 2.531 (16) DS / (-f1) : 0.075 0.528 0.072 0.009 0.054 0.021 0.053 (17) -f112 / f2 : 0.520 0.600 0.527 0.610 0.478 0.565 0.666 (18) -f11 / f2l : 2.125 2.428 2.031 2.619 2.402 3.103 2.283 (19) nd1 : 1.950 2.001 1.950 1.950 1.950 1.950 2.001 (20) nd2: 1.694 1.694 1.694 1.694 1.694 1.694 1.694 (21) nd3: 1.694 1.497 1.623 1.694 1.619 1.694 1.553

[0217] Each of the above embodiments shows a specific example of the present invention, and the present invention is not limited thereto. The following content can be appropriately adopted within the range that does not impair the optical performance of the optical system of the form of this application.

[0218] In the optical system of each of the above embodiments, the aperture stop may be configured to substitute its role with the lens frame without providing a member.

[0219] The lens surface of the lens constituting the optical system of each of the above embodiments may be a spherical surface or a flat surface, or may be an aspherical surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented, which is preferable. Also, it is preferable because deterioration of the rendering performance is small even when the image plane is shifted. When the lens surface is an aspherical surface, it may be any of an aspherical surface by grinding, a glass mold aspherical surface formed by molding glass into an aspherical shape with a mold, or a composite aspherical surface formed by forming a resin provided on the glass surface into an aspherical shape. Also, the lens surface may be a diffractive surface, and the lens may be a gradient-index lens (GRIN lens) or a plastic lens.

[0220] An antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the optical system of each of the above embodiments. Thereby, flare and ghost can be reduced, and optical performance with high contrast can be achieved.

[0221] Next, a camera including the optical system of the present embodiment will be described with reference to FIG. 15. FIG. 15 is a schematic diagram of a camera including the optical system of the present embodiment.

[0222] The camera 1 is a so-called omnidirectional camera that includes the optical systems according to the first embodiment as photographing lenses 2-1 and 2-2, one on each of one surface and the opposite surface thereof.

[0223] In the camera 1, light from an object (subject) (not shown) is condensed by the photographing lens 2-1 or 2-2 and reaches the imaging device 3-1 or 3-2. The imaging devices 3-1 and 3-2 convert the light from the subject into image data, respectively.

[0224] Also, when a release button (not shown) is pressed by the photographer, the image data is stored in a memory (not shown). In this way, the photographer can photograph the subject with the camera 1.

[0225] Here, the optical system of the first embodiment mounted on the camera 1 as the photographing lenses 2-1 and 2-2 is an optical system having a small size and good optical performance. Therefore, the camera 1 can achieve a small size and good optical performance. Note that even if a camera is configured by mounting the optical systems of the second to seventh embodiments as the photographing lenses 2-1 and 2-2, the same effects as those of the camera 1 can be obtained. Also, the number of optical systems mounted on the camera 1 is not limited to two, and may be one or three or more.

[0226] Finally, an outline of the manufacturing method of the optical system of the present embodiment will be described with reference to FIG. 16. FIG. 16 is a flowchart showing an outline of the manufacturing method of the optical system of the present embodiment.

[0227] The manufacturing method of the optical system of the present embodiment shown in FIG. 16 includes the following steps S1 to S2.

[0228] Step S1: Prepare, in order from the object side, a front group having at least three negative lenses and at least one positive lens, an aperture stop, and a rear group having at least four lenses.

[0229] Step S2: Make the optical system satisfy both of the following conditional expressions. (1) 8.90 < ΣT1 / f < 18.00 (2) 2.00 < (-f12) / f < 4.20 (3) 160.00° < 2ω However, ΣT1: Thickness on the optical axis of the front group f: Focal length of the optical system f12: Focal length of the second lens arranged from the object side in the front group 2ω: Entire angle of view of the optical system

[0230] In step S2, the optical system may satisfy the following conditional expressions together. (5) 1.30 < f / DS < 9.00 (4) 0.10 < D112 / (-f1) < 1.22 (3) 160.00° < 2ω However, f: Focal length of the optical system DS: Air space on the optical axis between the lens arranged most on the image side in the front group and the lens arranged most on the object side in the rear group D112: Air space on the optical axis between the lens arranged most on the object side in the front group and the second lens arranged from the object side f1: Focal length of the front group 2ω: Entire angle of view of the optical system

[0231] In step S2, the optical system may satisfy the following conditional expressions together. (7) 10.00 < TL / f < 27.00 (8) 3.00 < f2l / f < 5.40 (9 2.15 < f11 / f12 < 4.00 (3) 160.00° < 2ω However, TL: Total length of the entire optical system in terms of air equivalent length f: Focal length of the optical system f2l: Focal length of the lens arranged most on the image side in the rear group f11: Focal length of the lens arranged most on the object side in the front group f12: The focal length of the second lens arranged from the object side in the front group 2ω: The total angle of view of the optical system

[0232] According to the manufacturing method of the optical system of the present embodiment, an optical system having a small size and good imaging performance can be manufactured.

[0233] It should be understood by those skilled in the art that various changes, substitutions, and modifications can be added to this without departing from the spirit and scope of the present invention.

Explanation of reference signs

[0234] S Aperture stop I Image plane 1 Camera 2-1, 2-2 Photographing lenses 3-1, 3-2 Image sensors

Claims

1. Comprising, in order from the object side, a front group having a negative refractive power, an aperture stop, and a rear group having a positive refractive power, The front group has at least three negative lenses and at least one positive lens arranged in sequence from the object side, The rear group has at least four lenses, An optical system that satisfies the following conditional expressions simultaneously. 9.02 < ΣT1 / f < 18.00 2.00 < (-f12) / f < 4.20 160.00° < 2ω -3.00 < (r2 + r1) / (r2 - r1) < -2.00 1.10 < (-f11) / f2l < 3.50 However, ΣT1: The thickness on the optical axis of the front group f: The focal length of the optical system f12: The focal length of the second lens arranged from the object side in the front group 2ω: The total field angle of the optical system r1: The radius of curvature of the object-side surface of the lens arranged closest to the object side in the front group r2: The radius of curvature of the image-side surface of the lens arranged closest to the object side in the front group f11: The focal length of the lens arranged closest to the object side in the front group f2l: The focal length of the lens arranged closest to the image side in the rear group

2. The optical system according to Claim 1, which satisfies the following conditional expression. 1.30 < f / DS < 9.00 However, DS: The air space on the optical axis between the lens arranged closest to the image side in the front group and the lens arranged closest to the object side in the rear group

3. The optical system according to Claim 1 or 2, which satisfies the following conditional expression. 2.70 < f2 / f < 4.8 However, f2: The focal length of the rear group

4. Comprising, in order from the object side, a front group having a negative refractive power, an aperture stop, and a rear group having a positive refractive power, The front group has at least three negative lenses and at least one positive lens arranged in sequence from the object side, The rear group has at least four lenses, An optical system that satisfies the following conditional expressions simultaneously. 1.30 < f / DS < 9.00 0.10 < D112 / (-f1) < 1.22 160.00° < 2ω 2.00 < (-f12) / f < 4.20 -3.00 < (r2 + r1) / (r2 - r1) < -2.00 2.95 < f2 / f < 4.8 1.10 < (-f11) / f2l < 3.50 However, f: The focal length of the optical system DS: The air space on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group D112: The air space on the optical axis between the lens disposed closest to the object side in the front group and the second lens disposed from the object side f1: The focal length of the front group 2ω: The total angle of view of the optical system f12: The focal length of the second lens disposed from the object side in the front group r1: The radius of curvature of the object-side surface of the lens disposed closest to the object side in the front group r2: The radius of curvature of the image-side surface of the lens disposed closest to the object side in the front group f2: The focal length of the rear group f11: The focal length of the lens disposed closest to the object side in the front group f2l: The focal length of the lens disposed closest to the image side in the rear group **Claim 5** The optical system according to claim 1 or 4, satisfying the following formula 10.00 < TL / f < 27.00 wherein TL: The overall length of the optical system in terms of air equivalent length **Claim 6** The optical system according to claim 1 or 4, satisfying the following formula 3.00 < f2l / f < 5.40 **Claim 7** The optical system according to claim 1 or 4, satisfying the following formula 2.15 < f11 / f12 < 4.00 **Claim 8** Comprising, in order from the object side, a front group having a negative refractive power, an aperture stop, and a rear group having a positive refractive power The front group has at least three negative lenses and at least one positive lens arranged in sequence from the object side The rear group has at least four lenses An optical system that satisfies the following conditional formulas 10.00 < TL / f < 27.00 3.00 < f2l / f < 5.40 2.15 < f11 / f12 < 3.70 160.00° < 2ω 2.00 < (-f12 / f) < 4.20 2.78 < f2 / f < 4.8 1.30 < f / DS < 9.00 wherein TL: The overall length of the optical system in terms of air equivalent length f: The focal length of the optical system f2l: The focal length of the lens disposed closest to the image side in the rear group f11: The focal length of the lens disposed closest to the object side in the front group f12: The focal length of the second lens disposed from the object side in the front group 2ω: The total angle of view of the optical system f2: The focal length of the rear group DS: The air space on the optical axis between the lens disposed closest to the image side in the front group and the lens disposed closest to the object side in the rear group **Claim 9** The optical system according to claim 4 or 8, which satisfies the following formula. 8.90 < ΣT1 / f < 18.00 However, ΣT1: The thickness on the optical axis of the front group

10. The optical system according to claim 1 or 8, which satisfies the following formula. 0.10 < D112 / (-f1) < 1.22 However, D112: The air interval on the optical axis between the lens arranged closest to the object side in the front group and the second lens arranged from the object side f1: The focal length of the front group

11. The optical system according to claim 8, which satisfies the following formula. -3.00 < (r2 + r1) / (r2 - r1) < -2.00 However, r1: The radius of curvature of the object-side surface of the lens arranged closest to the object side in the front group r2: The radius of curvature of the image-side surface of the lens arranged closest to the object side in the front group

12. The optical system according to claim 8, which satisfies the following formula. 0.50 < f2l / f2 < 3.00 However, f2l: The focal length of the lens arranged closest to the image side in the rear group f2: The focal length of the rear group

13. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 3.00 < ΣT2 / f < 7.00 However, ΣT2: The thickness on the optical axis of the rear group

14. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 1.00 < (-f1) / f < 25.00 However, f1: The focal length of the front group

15. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 2.70 < f2 / f < 4.8 However, f2: The focal length of the rear group

16. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 0.45 < (-f1) / f2 < 6.00 However, f1: The focal length of the front group f2: The focal length of the rear group

17. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 1.50 < D112 / f < 4.50 However, D112: The air interval on the optical axis between the lens arranged closest to the object side in the front group and the second lens arranged from the object side

18. The optical system according to any one of claims 1, 4, and 8, which satisfies the following formula. 0.005 < DS / (-f1) < 0.700 However, DS: The air interval on the optical axis between the lens arranged most image-side in the front group and the lens arranged most object-side in the rear group f1: The focal length of the front group

19. The optical system according to any one of Claims 1, 4, and 8, satisfying the following formula. 0.20 < (-f112) / f2 < 1.00 However, f112: The combined focal length of the lens arranged most object-side in the front group and the second lens arranged from the object side f2: The focal length of the rear group

20. The optical system according to any one of Claims 1, 4, and 8, satisfying the following formula. 1.10 < (-f11) / f2l < 4.00 However, f11: The focal length of the lens arranged most object-side in the front group

21. The optical system according to any one of Claims 1, 4, and 8, satisfying the following formula. 1.85 < nd1 < 2.20 However, nd1: The refractive index based on the d-line of the lens arranged most object-side in the front group

22. The optical system according to any one of Claims 1, 4, and 8, satisfying the following formula. 1.50 < nd2 < 1.95 However, nd2: The refractive index based on the d-line of the second lens arranged from the object side in the front group

23. The optical system according to any one of Claims 1, 4, and 8, satisfying the following formula. 1.45 < nd3 < 1.90 However, nd3: The refractive index based on the d-line of the lens arranged most image-side in the rear group

24. An optical device having the optical system according to any one of Claims 1, 4, and 8.

Images