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

Abstract

The optical system (OL) includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. The second lens group and the fourth lens group move along the optical axis, and the optical system satisfies the following conditional expression: 0.50 < f1 / f3 < 2.00 (where f1 is the focal length of the first lens group, and f3 is the focal length of the third lens group).

Description

Technical Field

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

[0002] Conventionally, an optical system suitable for a photographic camera, an electronic still camera, a video camera, etc. has been proposed (for example, refer to Patent Document 1). However, it is difficult to achieve bright and good optical performance in such an optical system.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-16822 Summary of the invention

[0006] The optical system of the present invention comprises a first lens group having positive optical power, a second lens group having negative optical power, a third lens group having positive optical power, a fourth lens group having positive optical power, and a fifth lens group having negative optical power, which are arranged in order from the object side along the optical axis. When focusing, the second lens group and the fourth lens group move along the optical axis. The optical system satisfies the following conditional expression: 0.50<f1 / f3<2.00 Wherein, f1: the focal length of the first lens group, f3: focal length of the third lens group.

[0007] The optical device of the present invention is configured by including the above-mentioned optical system.

[0008] The manufacturing method of the optical system of the present invention comprises a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with positive optical power, a fourth lens group with positive optical power and a fifth lens group with negative optical power arranged in sequence from the object side along the optical axis, wherein the second lens group and the fourth lens group move along the optical axis during focusing, and the manufacturing method of the optical system comprises the step of arranging the lenses in the lens barrel in a manner satisfying the following conditional expression: 0.50<f1 / f3<2.00 Wherein, f1: the focal length of the first lens group, f3: focal length of the third lens group. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a diagram showing the lens structure of the optical system according to the first embodiment.

[0010] Figure 21 and 10 are diagrams showing various aberrations of the optical system of Example 1 when the optical system is in infinity focus.

[0011] Figure 3 It is a diagram showing the lens structure of the optical system according to the second embodiment.

[0012] Figure 4 1 and 10 are diagrams showing various aberrations of the optical system of Example 2 when the optical system is in infinity focus.

[0013] Figure 5 It is a diagram showing the lens structure of the optical system of the third embodiment.

[0014] Figure 6 1 and 10 are diagrams showing various aberrations of the optical system of Example 3 when the optical system is in infinity focus.

[0015] Figure 7 It is a diagram showing the lens structure of the optical system of the fourth embodiment.

[0016] Figure 8 1 and 10 are diagrams showing various aberrations of the optical system of Example 4 when the optical system is in infinity focus.

[0017] Fig. 9 It is a diagram showing the lens structure of the optical system of the fifth embodiment.

[0018] Fig.10 These are diagrams showing various aberrations of the optical system of Example 5 when focusing at infinity.

[0019] Fig.11 It is a diagram showing the structure of a camera including the optical system according to the present embodiment.

[0020] Fig.12 1 is a flowchart showing a method for manufacturing the optical system according to the present embodiment. DETAILED DESCRIPTION

[0021] The following describes a preferred embodiment of the present invention. Fig.11 A camera (optical device) having an optical system according to this embodiment will be described. Fig.11 As shown in FIG. 1 , the camera 1 is composed of a main body 2 and a photographic lens 3 mounted on the main body 2. The main body 2 includes an imaging element 4, a main body control unit (not shown) for controlling the operation of the digital camera, and a liquid crystal screen 5. The photographic lens 3 has an optical system OL composed of a plurality of lens groups and a lens position control mechanism (not shown) for controlling the position of each lens group. The lens position control mechanism is composed of a sensor for detecting the position of the lens group, a motor for moving the lens group forward and backward along the optical axis, a control circuit for driving the motor, and the like.

[0022] The light from the subject is focused by the optical system OL of the photographic lens 3 and reaches the image plane I of the imaging element 4. The light from the subject reaching the image plane I is photoelectrically converted by the imaging element 4 and recorded as digital image data in a memory (not shown). The digital image data recorded in the memory can be displayed on the LCD screen 5 according to the user's operation. In addition, the camera can be a mirrorless camera or a single-lens reflex camera with a quick return mirror. In addition, Fig.11 The optical system OL shown schematically shows the optical system included in the photographic lens 3 , and the lens structure of the optical system OL is not limited to this structure.

[0023] Next, the optical system of this embodiment is described. Figure 1 As shown, the optical system OL(1) as an example of the optical system OL of this embodiment includes a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with positive optical power, and a fifth lens group G5 with negative optical power, which are arranged in order from the object side along the optical axis. When focusing, the second lens group G2 and the fourth lens group G4 move along the optical axis.

[0024] With the above configuration, the optical system OL of the present embodiment satisfies the following conditional expression (1). 0.50<f1 / f3<2.00・・・(1) Where, f1: focal length of the first lens group f3: Focal length of the third lens group

[0025] According to this embodiment, a bright optical system having good optical performance and an optical device having the optical system can be obtained. The optical system OL of this embodiment can be Figure 3 The optical system OL(2) shown can also be Figure 5 The optical system OL(3) shown can also be Figure 7 The optical system OL(4) shown can also be Fig. 9 The optical system OL(5) is shown.

[0026] Conditional expression (1) specifies the focal length ratio of the first lens group G1 to the third lens group G3 within an appropriate range. By satisfying conditional expression (1), various aberrations such as spherical aberration, coma, field curvature, and distortion can be corrected well.

[0027] If the corresponding value of conditional expression (1) exceeds the upper limit, the optical power of the first lens group becomes too weak, so the lens diameter becomes large and it is difficult to achieve miniaturization. By setting the upper limit of conditional expression (1) to 1.90, 1.80, 1.70, 1.60, or 1.50, the effect of this embodiment can be made more reliable.

[0028] If the corresponding value of conditional expression (1) is lower than the lower limit, the optical power of the first lens group becomes too strong, so high-order spherical aberration, coma, field curvature, and distortion are generated in the infinite focus state, making it difficult to correct aberrations. By setting the lower limit of conditional expression (1) to 0.50, 0.60, 0.70, 0.80, or 0.90, the effect of this embodiment can be made more reliable.

[0029] The optical system OL of the present embodiment preferably satisfies the following conditional expression (2). 0.30<(-f2) / f3<2.00・・・(2) Where, f2: focal length of the second lens group G2

[0030] The conditional expression (2) specifies the focal length ratio of the second lens group G2 and the third lens group G3 to be within an appropriate range. By satisfying the conditional expression (2), various aberrations such as coma and field curvature can be corrected well.

[0031] If the corresponding value of conditional expression (2) exceeds the upper limit, the optical power of the second lens group becomes too weak, so the lens diameter becomes large and it is difficult to achieve miniaturization. By setting the upper limit of conditional expression (2) to 1.80, 1.60, 1.50, 1.40, or 1.30, the effect of this embodiment can be made more reliable.

[0032] If the corresponding value of conditional expression (2) is lower than the lower limit, the optical power of the second lens group becomes too strong, thus generating high-order coma and image curvature in the infinity focus state, making it difficult to correct aberrations. By setting the lower limit of conditional expression (2) to 0.40, 0.50, 0.60, 0.70, or 0.80, the effect of this embodiment can be made more reliable.

[0033] The optical system OL of the present embodiment preferably satisfies the following conditional expression (3). 1.10<f4 / f3<2.60・・・(3) Where, f4: focal length of the 4th lens group

[0034] The conditional expression (3) specifies the focal length ratio of the fourth lens group G4 to the third lens group G3 within an appropriate range. By satisfying the conditional expression (3), various aberrations such as spherical aberration and field curvature can be corrected well.

[0035] If the corresponding value of conditional expression (3) exceeds the upper limit, the optical power of the fourth lens group becomes too weak, so the lens diameter becomes large and it is difficult to achieve miniaturization. By setting the upper limit of conditional expression (3) to 2.50, 2.40, 2.30, 2.20, or 2.10, the effect of this embodiment can be made more reliable.

[0036] If the corresponding value of conditional expression (3) is lower than the lower limit, the optical power of the fourth lens group becomes too strong, thus generating high-order spherical aberration and image curvature, making it difficult to correct aberrations. By setting the lower limit of conditional expression (3) to 1.20, 1.30, 1.40, 1.50, or 1.60, the effect of this embodiment can be made more reliable.

[0037] The optical system OL of the present embodiment preferably satisfies the following conditional expression (4). 0.35<(-f5) / f3<2.50・・・(4) Where, f5: focal length of the 5th lens group G5

[0038] Conditional expression (4) specifies the focal length ratio between the fifth lens group G5 and the third lens group G3 within an appropriate range. By satisfying conditional expression (4), various aberrations such as field curvature and distortion can be corrected well.

[0039] If the corresponding value of conditional expression (4) exceeds the upper limit, the optical power of the fifth lens group becomes too weak, so the lens diameter becomes large and it is difficult to achieve miniaturization. By setting the upper limit of conditional expression (4) to 2.40, 2.30, 2.20, 2.10, or 2.00, the effect of this embodiment can be made more reliable.

[0040] If the corresponding value of conditional expression (4) is lower than the lower limit, the optical power of the fifth lens group becomes too strong, thus generating high-order image curvature and distortion, making it difficult to correct aberrations. By setting the lower limit of conditional expression (4) to 0.50, 0.70, 0.80, 0.90, or 1.00, the effect of this embodiment can be made more reliable.

[0041] The optical system OL of the present embodiment preferably satisfies the following conditional expression (5). 0.30<D1 / D3<2.00・・・(5) Where D1: The length on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image plane side D3: The length on the optical axis from the lens surface of the third lens group closest to the object side to the lens surface of the third lens group closest to the image plane side

[0042] Conditional expression (5) specifies the ratio of the length of the first lens group to the length of the third lens group on the optical axis within an appropriate range. By satisfying conditional expression (5), various aberrations including spherical aberration, coma, and axial chromatic aberration can be corrected well.

[0043] If the corresponding value of conditional expression (5) exceeds the upper limit, the length of the first lens group becomes too large, making it difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (5) to 1.80, 1.70, 1.60, 1.50, or 1.40, the effect of this embodiment can be made more reliable.

[0044] If the corresponding value of conditional expression (5) is lower than the lower limit, the length of the third lens group becomes too large, making it difficult to correct image curvature and distortion. By setting the lower limit of conditional expression (5) to 0.40, 0.50, 0.60, 0.70, or 0.80, the effect of this embodiment can be made more reliable.

[0045] The optical system OL of the present embodiment preferably satisfies the following conditional expression (6). 0.01<D2 / D3<0.20・・・(6) Where D2: The length on the optical axis from the lens surface of the second lens group closest to the object side to the lens surface of the second lens group closest to the image plane side D3: The length on the optical axis from the lens surface of the third lens group closest to the object side to the lens surface of the third lens group closest to the image plane side

[0046] Conditional expression (6) is a conditional expression for regulating the ratio of the length of the second lens group to the length on the optical axis of the third lens group within an appropriate range. By satisfying conditional expression (6), various aberrations including spherical aberration, coma, and axial chromatic aberration can be corrected well.

[0047] If the corresponding value of conditional expression (6) exceeds the upper limit, the length of the second lens group becomes too large, making it difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (6) to 0.18, 0.16, 0.14, 0.12, or 0.10, the effect of this embodiment can be made more reliable.

[0048] If the corresponding value of conditional expression (6) is lower than the lower limit, the length of the third lens unit becomes too large, making it difficult to correct field curvature and distortion. By setting the lower limit of conditional expression (6) to 0.02 or 0.03, the effect of this embodiment can be made more reliable.

[0049] The optical system OL of the present embodiment preferably satisfies the following conditional expression (7). 0.01<D4 / D3<1.00・・・(7) Where D4 is the length on the optical axis from the lens surface of the 4th lens group closest to the object side to the lens surface of the 4th lens group closest to the image plane side. D3: The length on the optical axis from the lens surface of the third lens group closest to the object side to the lens surface of the third lens group closest to the image plane side

[0050] Conditional expression (7) specifies the ratio of the length of the fourth lens group to the length on the optical axis of the third lens group within an appropriate range. By satisfying conditional expression (7), various aberrations including spherical aberration, coma, and axial chromatic aberration can be corrected well.

[0051] If the corresponding value of conditional expression (7) exceeds the upper limit, the length of the fourth lens group becomes too large, making it difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (7) to 0.90, 0.80, 0.70, 0.60, or 0.50, the effect of this embodiment can be made more reliable.

[0052] If the corresponding value of conditional expression (7) is lower than the lower limit, the length of the third lens group becomes too large, so it is difficult to correct image curvature and distortion. By setting the lower limit of conditional expression (7) to 0.04, 0.06, 0.08, 0.10, or 0.12, the effect of this embodiment can be made more reliable.

[0053] The optical system OL of the present embodiment preferably satisfies the following conditional expression (8). 0.01<D5 / D3<1.50・・・(8) Where D5: The length on the optical axis from the lens surface of the fifth lens group closest to the object side to the lens surface of the fifth lens group closest to the image plane side D3: The length on the optical axis from the lens surface of the third lens group closest to the object side to the lens surface of the third lens group closest to the image plane side

[0054] Conditional expression (8) specifies the ratio of the length of the fifth lens group to the length on the optical axis of the third lens group within an appropriate range. By satisfying conditional expression (8), various aberrations including spherical aberration, coma, and axial chromatic aberration can be corrected well.

[0055] If the corresponding value of conditional expression (8) exceeds the upper limit, the length of the fifth lens group becomes too large, making it difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (8) to 1.20, 1.00, 0.90, 0.80, or 0.70, the effect of this embodiment can be made more reliable.

[0056] If the corresponding value of conditional expression (8) is lower than the lower limit, the length of the third lens group becomes too large, making it difficult to correct image curvature and distortion. By setting the lower limit of conditional expression (8) to 0.02, 0.03, 0.04, 0.05, or 0.06, the effect of this embodiment can be made more reliable.

[0057] The optical system OL of the present embodiment preferably satisfies the following conditional expression (9). 0.05<(-f2) / f4<1.40・・・(9) Where, f2: focal length of the second lens group f4: Focal length of the 4th lens group

[0058] Conditional expression (9) specifies the focal length ratio between the second lens group and the fourth lens group that move during focusing within an appropriate range. By satisfying conditional expression (9), various aberrations can be corrected well from infinity to the closest point.

[0059] If the corresponding value of conditional expression (9) exceeds the upper limit, the optical power of the second lens group becomes too weak, so the movement amount of the second lens group becomes too large, and the total length of the optical system becomes longer. By setting the upper limit of conditional expression (9) to 1.20, 1.00, 0.90, 0.80, or 0.70, the effect of this embodiment can be made more reliable.

[0060] If the corresponding value of conditional expression (9) is lower than the lower limit, the power of the second lens group becomes too strong, thus generating spherical aberration. When focusing, the variation of spherical aberration from infinity to the closest distance becomes large, making it difficult to correct aberration. By setting the lower limit of conditional expression (9) to 0.10, 0.20, 0.30, or 0.40, the effect of this embodiment can be made more reliable.

[0061] The optical system OL of the present embodiment preferably satisfies the following conditional expression (10). 0.25<Mv2 / Mv4<1.35・・・(10) Where Mv2: The absolute value of the movement of the second lens group on the optical axis during focusing Mv4: The absolute value of the movement of the fourth lens group on the optical axis during focusing

[0062] Conditional expression (10) is a conditional expression that specifies the ratio of the moving distances of the second lens group and the fourth lens group on the optical axis when focusing within an appropriate range. By satisfying conditional expression (10), various aberrations can be well corrected from infinity to the closest. In addition, in this embodiment, the movement amount of the second lens group when focusing is the movement amount of the second lens group when focusing from an infinitely distant object to a close object. In addition, the movement amount of the fourth lens group when focusing is the movement amount of the fourth lens group when focusing from an infinitely distant object to a close object.

[0063] If the corresponding value of conditional expression (10) exceeds the upper limit, the movement amount of the second lens group becomes too large, and the total length of the optical system becomes longer. By setting the upper limit of conditional expression (10) to 1.30, 1.25, 1.20, 1.15, or 1.10, the effect of this embodiment can be made more reliable.

[0064] If the corresponding value of conditional expression (10) is lower than the lower limit, the refractive power of the second lens group becomes too strong, so when focusing, the variation of spherical aberration and coma from infinity to the closest distance becomes large, making it difficult to correct aberrations. By setting the lower limit of conditional expression (10) to 0.30, 0.35, 0.40, 0.45, or 0.50, the effect of this embodiment can be made more reliable.

[0065] The optical system OL of the present embodiment preferably satisfies the following conditional expression (11). 1.00<β2 / β4<10.00・・・(11) Where, β2: lateral magnification of the second lens group β4: Lateral magnification of the fourth lens group

[0066] Conditional expression (11) is a conditional expression for regulating the ratio of the lateral magnification of the second lens group and the fourth lens group as the focusing group within an appropriate range. By satisfying conditional expression (11), various aberrations can be well corrected from infinity to the closest. In addition, in the present embodiment, the lateral magnification of the second lens group refers to the lateral magnification of the second lens group when focusing at infinity. In addition, the lateral magnification of the fourth lens group refers to the lateral magnification of the fourth lens group when focusing at infinity.

[0067] If the corresponding value of conditional expression (11) exceeds the upper limit, the lateral magnification of the second lens group becomes too large, and the changes in spherical aberration and coma become large during focusing, making it difficult to correct aberrations. By setting the upper limit of conditional expression (11) to 9.00, 8.00, 7.00, 6.50, and 6.00, the effect of this embodiment can be made more reliable.

[0068] If the corresponding value of conditional expression (11) is lower than the lower limit, the lateral magnification of the second lens group becomes too small, the movement amount of the second lens group during focusing becomes large, and the total optical length becomes longer. By setting the lower limit of conditional expression (11) to 1.50, 2.00, 2.50, 2.75, 3.00, the effect of this embodiment can be made more reliable.

[0069] In the optical system OL of this embodiment, the second lens group is preferably composed of a single lens. By making the second lens group composed of a single lens, the optical system can be made lighter. By making it lighter, it can be driven by, for example, a stepping motor.

[0070] In the optical system OL of the present embodiment, the fourth lens group is preferably composed of one cemented lens. By making the fourth lens group consist of one cemented lens, it is possible to suppress the variation of chromatic aberration during focusing.

[0071] In the optical system OL of this embodiment, it is preferable to have an aperture stop disposed on the image side of the second lens unit. By having an aperture stop on the image side of the second lens unit, spherical aberration can be corrected from infinity to the closest point.

[0072] The optical system OL of the present embodiment preferably satisfies the following conditional expressions (12) and (13). 1.80<nd1・・・(12) 17.00<νd1<35.00・・・(13) Where, nd1: the refractive index of the lens closest to the object side of the optical system OL based on the d line νd1: Abbe number of the lens closest to the object side of the optical system OL based on the d line

[0073] Conditional expression (12) defines an appropriate range for the refractive index of the lens closest to the object side of the optical system OL of the present embodiment. When conditional expression (12) is satisfied, the occurrence of axial chromatic aberration can be suppressed.

[0074] If the corresponding value of conditional expression (12) is lower than the lower limit, it is difficult to suppress the change of the axial chromatic aberration. By setting the lower limit of conditional expression (12) to 1.85 or 1.90, the effect of this embodiment can be made more reliable. In addition, by setting the upper limit of conditional expression (12) to 2.00, the effect of this embodiment can be made more reliable.

[0075] Conditional expression (13) defines an appropriate range for the Abbe number of the lens closest to the object side of the optical system OL of the present embodiment. By satisfying conditional expression (13), the occurrence of axial chromatic aberration can be suppressed.

[0076] If the corresponding value of the conditional expression (13) exceeds the upper limit, it is difficult to suppress the variation of the generated axial chromatic aberration. By setting the upper limit of the conditional expression (13) to 34.00, 33.00, 32.00, or 31.00, the effect of the present embodiment can be made more reliable.

[0077] If the corresponding value of the conditional expression (13) is lower than the lower limit, it is difficult to suppress the variation of the generated axial chromatic aberration. By setting the lower limit of the conditional expression (13) to 18.50, 19.00, 19.50, or 20.00, the effect of the present embodiment can be made more reliable.

[0078] The fifth lens group of the optical system OL of the present embodiment preferably includes at least one lens satisfying the following conditional expressions (14) and (15). 1.80<nd2・・・(14) 17.00<νd2<35.00・・・(15) Where, nd2: the refractive index of the lens of the fifth lens group of the optical system OL based on the d line νd2: Abbe number of the lens of the fifth lens group of the optical system OL based on the d line

[0079] Conditional expression (14) is a conditional expression for specifying an appropriate range of the refractive index of the lens of the fifth lens group of the optical system OL of the present embodiment. In addition, conditional expression (15) is a conditional expression for specifying an appropriate range of the Abbe number of the lens of the fifth lens group of the optical system OL of the present embodiment. By having the fifth lens group include lenses satisfying conditional expressions (14) and (15), chromatic aberration of magnification can be corrected well.

[0080] If the corresponding value of conditional expression (14) is lower than the lower limit, it is difficult to suppress the change of magnification chromatic aberration. By setting the lower limit of conditional expression (14) to 1.85 or 1.90, the effect of this embodiment can be made more reliable. In addition, by setting the upper limit of conditional expression (14) to 2.00, the effect of this embodiment can be made more reliable.

[0081] If the corresponding value of the conditional expression (15) exceeds the upper limit, it is difficult to suppress the variation of the generated chromatic aberration of magnification. By setting the upper limit of the conditional expression (15) to 34.00, 33.00, 32.00, or 31.00, the effect of the present embodiment can be made more reliable.

[0082] If the corresponding value of the conditional expression (15) is lower than the lower limit, it is difficult to suppress the variation of the chromatic aberration of magnification. By setting the lower limit of the conditional expression (15) to 18.50, 19.00, 19.50, or 20.00, the effect of the present embodiment can be made more reliable.

[0083] In the optical system OL of this embodiment, it is preferable that the third lens group has at least five lenses. When the third lens group has at least five lenses, spherical aberration and coma aberration can be corrected efficiently.

[0084] In the optical system OL of the present embodiment, it is preferred that the third lens group includes at least two cemented lenses. When the third lens group includes at least two cemented lenses, axial chromatic aberration can be efficiently corrected.

[0085] It is preferable that the lens closest to the object side of the optical system OL of the present embodiment satisfies the following conditional expression (16). 1.00<(L1r1+L1r2) / (L1r2-L1r1)<9.00・・・(16) Where, L1r1: The radius of curvature of the object-side lens surface of the lens closest to the object side of the optical system OL L1r2: The curvature radius of the image-side lens surface of the lens closest to the object side of the optical system OL

[0086] Conditional expression (16) specifies the relationship between the object-side and image-side curvature radii of the lens disposed closest to the object in the optical system OL of the present embodiment within an appropriate range. By satisfying conditional expression (16), the occurrence of spherical aberration can be suppressed.

[0087] If the corresponding value of conditional expression (16) exceeds the upper limit value, the curvature difference between the object side lens surface and the image side lens surface of the lens closest to the object side becomes too small, making it difficult to correct various aberrations such as spherical aberration. By setting the upper limit value of conditional expression (16) to 8.00, 7.00, 6.50, 6.00, and 5.50, the effect of this embodiment can be made more reliable.

[0088] If the corresponding value of conditional expression (16) is lower than the lower limit, the image side lens surface of the lens closest to the object side becomes too slow, making it difficult to correct spherical aberration. By setting the lower limit of conditional expression (16) to 1.10, 1.20, 1.30, 1.40, or 1.50, the effect of this embodiment can be made more reliable.

[0089] The optical system OL of the present embodiment preferably satisfies the following conditional expression (17). 5.00°<ω<16.00°・・・(17) Where, ω: half field angle of the optical system OL in the infinite focus state

[0090] Conditional expression (17) is a conditional expression for regulating the half angle of view of the optical system OL of the present embodiment within an appropriate range. By satisfying conditional expression (17), a bright optical system can be realized.

[0091] In order to make the effect of the present embodiment reliable, it is preferred to set the upper limit value of the conditional expression (17) to 15.00°. In addition, by setting the upper limit value of the conditional expression (17) to 14.00°, 13.00°, 12.00°, and further setting it to 11.00°, the effect of the present embodiment can be made more reliable. In order to make the effect of the present embodiment reliable, it is preferred to set the lower limit value of the conditional expression (17) to 6.00°. In addition, by setting the lower limit value of the conditional expression (17) to 7.00°, and further setting it to 8.00°, the effect of the present embodiment can be made more reliable.

[0092] Next, refer to Fig.12 , a manufacturing method of the optical system OL of the present embodiment is briefly described. First, a first lens group G1 having positive focal power, a second lens group G2 having negative focal power, a third lens group G3 having positive focal power, a fourth lens group G4 having positive focal power, and a fifth lens group G5 having negative focal power are sequentially arranged along the optical axis from the object side (step ST1). Next, the second lens group G2 and the fourth lens group G4 are arranged in such a manner that they move along the optical axis when focusing (step ST2). Then, each lens is arranged in the lens barrel in such a manner that the above-mentioned conditional expression (1) is satisfied (step ST3). According to such a manufacturing method, a bright optical system having good optical performance can be manufactured.

[0093] Example

[0094] Hereinafter, an optical system OL according to an example of the present embodiment will be described based on the drawings. Figure 1 , Figure 3 , Figure 5 , Figure 7 , Fig. 9 1 is a cross-sectional view showing the structure of the optical system OL {OL(1) to OL(5)} according to the first to fifth embodiments. Figure 1 , Figure 3 , Figure 5 , Figure 7 , Fig. 9 In the figure, arrows are used to indicate the movement direction of each lens group along the optical axis when focusing from infinity to a close object.

[0095] In these Figure 1 , Figure 3 , Figure 5 , Figure 7 , Fig. 9In the embodiment, each lens group is represented by a combination of a symbol G and a number, and each lens is represented by a combination of a symbol L and a number. In this case, in order to prevent the types and numbers of symbols and numbers from becoming large and complicated, a combination of symbols and numbers is used independently in each embodiment to represent a lens group, etc. Therefore, even if the same combination of symbols and numbers is used between embodiments, it does not mean that the same structure is used.

[0096] Tables 1 to 6 are shown below, where Table 1 is a table showing various parameter data in the first embodiment, Table 2 is a table showing various parameter data in the second embodiment, Table 3 is a table showing various parameter data in the third embodiment, Table 4 is a table showing various parameter data in the fourth embodiment, and Table 5 is a table showing various parameter data in the fifth embodiment. In each embodiment, the d line (wavelength λ=587.6nm) and the g line (wavelength λ=435.8nm) are selected as the calculation objects of the aberration characteristics.

[0097] In the table of [Overall parameters], f represents the focal length of the entire lens system when focusing at infinity, FNО represents the F value when focusing at infinity, ω represents the half angle of view when focusing at infinity (unit: ° (degrees), and Y represents the image height. TL represents the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image plane side of the optical system plus Bf (back focal length), and Bf represents the distance on the optical axis from the lens surface closest to the image plane side of the optical system to the image plane (air conversion distance).

[0098] In the table of [Overall Parameters], D1 to D5 represent the length on the optical axis from the lens surface closest to the object side of each lens group to the lens surface closest to the image side of each lens group in the first to fifth lens groups. Mv2 and Mv4 represent the absolute values ​​of the movement of the second lens group and the fourth lens group when focusing from the infinite focus state to the close focus state. β2 and β4 represent the lateral magnifications of the second lens group and the fourth lens group in the infinite focus state.

[0099] In the table of [lens parameters], the surface number indicates the order of the optical surfaces from the object side along the direction of light travel, R indicates the radius of curvature of each optical surface (the surface with the center of curvature on the image side is a positive value), D indicates the distance on the optical axis from the optical surface to the next optical surface (or image surface), i.e., the surface interval, nd indicates the refractive index of the material of the optical component with respect to the d-line (wavelength λ=587.6nm), and νd indicates the Abbe number of the material of the optical component based on the d-line. The "∞" of the radius of curvature indicates a plane or an opening, and (aperture S) indicates the aperture stop S. The refractive index of air nd=1.00000 is omitted. In the case of an aspherical optical surface, the surface number is marked with an *, and the paraxial curvature radius is shown in the column of the radius of curvature R.

[0100] In the table of [Aspheric surface data], for the aspheric surface shown in [Lens parameters], its shape is expressed by the following formula (A). X(y) represents the distance along the optical axis from the tangent plane at the vertex of the aspheric surface to the position on the aspheric surface at height y (the amount of concavity), R represents the curvature radius of the reference spherical surface (paraxial curvature radius), κ represents the cone constant, and Ai represents the i-th order aspheric coefficient. "En" represents "×10 -n For example, 1.234E-05=1.234×10 -5 In addition, the secondary aspheric coefficient A2 is 0, and its description is omitted.

[0101] X(y)=(y 2 / R) / {1+(1-κ×y 2 / R 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 (A)

[0102] In the table of [Variable Interval Data], the surface number i of the starting surface with the surface interval (variable) in the table of [Lens Parameters] is used to indicate the surface interval in the infinite focus state and the surface interval in the close focus state. In the table of [Variable Interval Data], f indicates the focal length, FNO indicates the F value, and ω indicates the half angle of view for the infinite focus state and the close focus state.

[0103] The table of [Lens Group Data] shows the initial surface (the surface closest to the object side) and the focal length of each lens group.

[0104] In the following, all parameter values, such as focal length f, radius of curvature R, surface spacing D, and other lengths, are generally expressed in "mm" unless otherwise specified. However, the optical system is not limited to this because the same optical performance can be achieved even if it is scaled up or down.

[0105] The description of the table so far is common to all the embodiments, and repeated description will be omitted below.

[0106] (First embodiment)

[0107] use Figure 1-2 and Table 1 illustrate the first embodiment. Figure 11 is a diagram showing the lens structure of the optical system of the first embodiment. The optical system OL (1) of the first embodiment is composed of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with positive optical power, and a fifth lens group with negative optical power, which are arranged in sequence from the object side along the optical axis. When focusing from an infinitely distant object to a close-up object, the second lens group G2 and the fourth lens group G4 move along the optical axis, specifically, the second lens group G2 moves toward the image plane side, and the fourth lens group G4 moves toward the object side, and the intervals between adjacent lens groups change. In addition, when focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane I. The symbol (+) or (-) attached to each lens group number indicates the optical power of each lens group, and this is also the case in all the following embodiments.

[0108] The second lens group G2 as the first focusing group is arranged on the object side of the aperture stop S. During focusing, the position of the aperture stop S is fixed relative to the image plane I. In this embodiment, the aperture stop S is arranged between the second lens group G2 and the third lens group G3.

[0109] The first lens group G1 is composed of a positive meniscus lens L11 with a convex surface facing the object side, a positive meniscus lens L12 with a convex surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L13 and a biconcave negative lens L14, and a positive meniscus lens L15 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The lens surface on the object side of the positive meniscus lens L15 is an aspherical surface. In addition, the lens L11 of the first lens group G1 is a lens that satisfies the above-mentioned conditional expressions (12) and (13).

[0110] The second lens group G2 is composed of a biconcave negative lens L21. When focusing, the second lens group G2 moves along the optical axis toward the image plane I. An aperture stop S is arranged on the image side of the second lens group G2.

[0111] The third lens group G3 is composed of a cemented lens formed by a biconcave negative lens L31 and a positive meniscus lens L32 with a convex object side arranged in sequence along the optical axis, a cemented lens formed by a biconcave negative lens L33 and a biconvex positive lens L34, and a biconvex positive lens L35.

[0112] The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42 arranged in order from the object side along the optical axis. When focusing, the fourth lens group G4 moves along the optical axis toward the object side.

[0113] The fifth lens group G5 is composed of a cemented lens formed by cementing a biconvex positive lens L51 and a biconcave negative lens L52 arranged in sequence from the object side along the optical axis, and a negative meniscus lens L53 with a convex surface facing the image side. The object side surface of the negative meniscus lens L53 is an aspherical surface. An image surface I is arranged on the image side of the fifth lens group G5. In addition, the lens L51 of the fifth lens group G5 is a lens that satisfies the above-mentioned conditional expressions (14) and (15).

[0114] Table 1 below shows the values ​​of parameters of the optical system of the first embodiment.

[0115] (Table 1)

[0116] [Overall parameters]

[0117] [Lens parameters]

[0118] [Aspherical surface data]

[0119] [Variable interval data]

[0120] [Lens group data]

[0121] Figure 2 These are various aberration diagrams when the optical system of the first embodiment is focused at infinity. In the various aberration diagrams when focused at infinity, FNO represents the F value, and A represents the maximum photographic half-field angle in the negative direction. In addition, the spherical aberration diagram shows the F value or the value of the numerical aperture corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram respectively show the maximum value of the half-field angle, and the coma diagram shows the value of each half-field angle. d represents the d-line (wavelength λ=587.6nm), and g represents the g-line (wavelength λ=435.8nm). In the astigmatism diagram, the solid line represents the sagittal image plane, and the dotted line represents the meridional image plane. In addition, in the aberration diagrams of the various embodiments shown below, the same symbols as those of the present embodiment are used, and repeated descriptions are omitted.

[0122] As can be seen from the aberration diagrams, the optical system of Example 1 corrects various aberrations well and has excellent imaging performance.

[0123] (Second embodiment)

[0124] use Figure 3-4and Table 2 illustrate the second embodiment. Figure 3 : is a diagram showing the lens structure of the optical system of the second embodiment. The optical system OL (2) of the second embodiment is composed of a first lens group G1 with positive optical focal length, a second lens group G2 with negative optical focal length, a third lens group G3 with positive optical focal length, a fourth lens group G4 with positive optical focal length, and a fifth lens group with negative optical focal length, which are arranged in sequence from the object side along the optical axis. When focusing from an infinitely distant object to a close-up object, the second lens group G2 and the fourth lens group G4 move along the optical axis, specifically, the second lens group G2 moves toward the image plane side, and the fourth lens group G4 moves toward the object side, and the intervals between adjacent lens groups change. In addition, when focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane I.

[0125] The second lens group G2 as the first focusing group is arranged on the object side of the aperture stop S. During focusing, the position of the aperture stop S is fixed relative to the image plane I. In this embodiment, the aperture stop S is arranged between the second lens group G2 and the third lens group G3.

[0126] The first lens group G1 is composed of a positive meniscus lens L11 with a convex surface facing the object side, a positive meniscus lens L12 with a convex surface facing the object side, a cemented lens formed by cementing a positive meniscus lens L13 with a convex surface facing the object side and a negative meniscus lens L14 with a convex surface facing the object side, and a positive meniscus lens L15 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The lens surfaces on the object side and the image side of the positive meniscus lens L15 are aspherical surfaces. In addition, the lens L11 of the first lens group G1 is a lens that satisfies the above-mentioned conditional expressions (12) and (13).

[0127] The second lens group G2 is composed of a biconcave negative lens L21. When focusing, the second lens group G2 moves along the optical axis toward the image plane I. An aperture stop S is arranged on the image side of the second lens group G2.

[0128] The third lens group G3 is composed of a cemented lens formed by a negative meniscus lens L31 with a convex surface facing the object side and a positive meniscus lens L32 with a convex surface facing the object side, a cemented lens formed by a biconvex positive lens L33 and a negative meniscus lens L34 with a convex surface facing the image side, and a biconvex positive lens L35. The lens surface on the image side of the positive meniscus lens L32 is an aspherical surface.

[0129] The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42 arranged in order from the object side along the optical axis. When focusing, the fourth lens group G4 moves along the optical axis toward the object side.

[0130] The fifth lens group G5 is composed of a cemented lens formed by cementing a biconvex positive lens L51 and a biconcave negative lens L52 arranged in order from the object side along the optical axis, and a negative meniscus lens L53 with a convex surface facing the image side. An image surface I is arranged on the image side of the fifth lens group G5. In addition, the lens L51 of the fifth lens group G5 is a lens that satisfies the above-mentioned conditional expressions (14) and (15).

[0131] Table 2 below lists the values ​​of parameters of the optical system of the second embodiment.

[0132] (Table 2)

[0133] [Overall parameters]

[0134] [Lens parameters]

[0135] [Aspherical surface data]

[0136] [Variable interval data]

[0137] [Lens group data]

[0138] Figure 4 1 and 10 are diagrams of various aberrations when the optical system of Example 2 is in infinity focus. As can be seen from the diagrams, the optical system of Example 2 has various aberrations corrected well and has excellent imaging performance.

[0139] (Third embodiment)

[0140] use Figure 5-6 And Table 3 illustrate the third embodiment. Figure 5: is a diagram showing the lens structure of the optical system of the third embodiment. The optical system OL (3) of the third embodiment is composed of a first lens group G1 with positive optical focal length, a second lens group G2 with negative optical focal length, a third lens group G3 with positive optical focal length, a fourth lens group G4 with positive optical focal length, and a fifth lens group with negative optical focal length, which are arranged in sequence from the object side along the optical axis. When focusing from an infinitely distant object to a close-up object, the second lens group G2 and the fourth lens group G4 move along the optical axis, specifically, the second lens group G2 moves toward the image plane side, and the fourth lens group G4 moves toward the object side, and the intervals between adjacent lens groups change. In addition, when focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane I.

[0141] The second lens group G2 as the first focusing group is arranged on the object side of the aperture stop S. During focusing, the position of the aperture stop S is fixed relative to the image plane I. In this embodiment, the aperture stop S is arranged between the second lens group G2 and the third lens group G3.

[0142] The first lens group G1 is composed of a positive meniscus lens L11 with a convex surface facing the object side, a positive meniscus lens L12 with a convex surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L13 and a biconcave negative lens L14, and a positive meniscus lens L15 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The lens surface on the object side of the positive meniscus lens L15 is an aspherical surface. In addition, the lens L11 of the first lens group G1 is a lens that satisfies the above-mentioned conditional expressions (12) and (13).

[0143] The second lens group G2 is composed of a biconcave negative lens L21. When focusing, the second lens group G2 moves along the optical axis toward the image plane I. An aperture stop S is arranged on the image side of the second lens group G2.

[0144] The third lens group G3 is composed of a cemented lens formed by a biconcave negative lens L31 and a positive meniscus lens L32 with a convex object side arranged in sequence along the optical axis, a cemented lens formed by a biconcave negative lens L33 and a biconvex positive lens L34, and a biconvex positive lens L35.

[0145] The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42 arranged in order from the object side along the optical axis. When focusing, the fourth lens group G4 moves along the optical axis toward the object side.

[0146] The fifth lens group G5 is composed of a cemented lens formed by cementing a biconvex positive lens L51 and a biconcave negative lens L52 arranged in order from the object side along the optical axis, and a negative meniscus lens L53 with a convex surface facing the image side. An image surface I is arranged on the image side of the fifth lens group G5. In addition, the lens L51 of the fifth lens group G5 is a lens that satisfies the above-mentioned conditional expressions (14) and (15).

[0147] Table 3 below lists the values ​​of the parameters of the optical system of the third embodiment.

[0148] (Table 3)

[0149] [Overall parameters]

[0150] [Lens parameters]

[0151] [Aspherical surface data]

[0152] [Variable interval data]

[0153] [Lens group data]

[0154] Figure 6 1 and 10 are diagrams of various aberrations when the optical system of Example 3 is in infinity focus. As can be seen from the diagrams, the optical system of Example 3 has various aberrations corrected well and has excellent imaging performance.

[0155] (Fourth embodiment)

[0156] use Figure 7-Figure 8 And Table 4 illustrate the fourth embodiment. Figure 7: is a diagram showing the lens structure of the optical system of the fourth embodiment. The optical system OL (4) of the fourth embodiment is composed of a first lens group G1 with positive optical focal length, a second lens group G2 with negative optical focal length, a third lens group G3 with positive optical focal length, a fourth lens group G4 with positive optical focal length, and a fifth lens group with negative optical focal length, which are arranged in sequence from the object side along the optical axis. When focusing from an infinitely distant object to a close-up object, the second lens group G2 and the fourth lens group G4 move along the optical axis, specifically, the second lens group G2 moves toward the image plane side, and the fourth lens group G4 moves toward the object side, and the intervals between adjacent lens groups change. In addition, when focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane I.

[0157] The second lens group G2 as the first focusing group is arranged on the object side of the aperture stop S. During focusing, the position of the aperture stop S is fixed relative to the image plane I. In this embodiment, the aperture stop S is arranged between the second lens group G2 and the third lens group G3.

[0158] The first lens group G1 is composed of a positive meniscus lens L11 with a convex surface facing the object side, a positive meniscus lens L12 with a convex surface facing the object side, a cemented lens formed by cementing a positive meniscus lens L13 with a convex surface facing the object side and a negative meniscus lens L14 with a convex surface facing the object side, and a positive meniscus lens L15 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The lens surface on the object side of the positive meniscus lens L15 is an aspherical surface. In addition, the lens L11 of the first lens group G1 is a lens that satisfies the above-mentioned conditional expressions (12) and (13).

[0159] The second lens group G2 is composed of a negative meniscus lens L21 with a convex object side. The lens surface of the negative meniscus lens L21 on the image side is an aspherical surface. When focusing, the second lens group G2 moves along the optical axis toward the image plane I. An aperture stop S is arranged on the image side of the second lens group G2.

[0160] The third lens group G3 is composed of a joined lens formed by a negative meniscus lens L31 with a convex surface facing the object side and a positive meniscus lens L32 with a convex surface facing the object side, which are arranged in sequence from the object side along the optical axis, a joined lens formed by a biconvex positive lens L33 and a negative meniscus lens L34 with the convex surface facing the image side, and a biconvex positive lens L35.

[0161] The fourth lens group G4 is composed of a biconvex positive lens L41. The lens surfaces on the object side and the image side of the positive lens L41 are aspherical surfaces. When focusing, the fourth lens group G4 moves along the optical axis toward the object side.

[0162] The fifth lens group G5 is composed of a cemented lens formed by cementing a biconvex positive lens L51 and a biconcave negative lens L52 arranged in order from the object side along the optical axis, and a negative meniscus lens L53 with a convex surface facing the image side. An image surface I is arranged on the image side of the fifth lens group G5. In addition, the lens L51 of the fifth lens group G5 is a lens that satisfies the above-mentioned conditional expressions (14) and (15).

[0163] Table 4 below lists the values ​​of parameters of the optical system of Example 4.

[0164] (Table 4)

[0165] [Overall parameters]

[0166] [Lens parameters]

[0167] [Aspherical surface data]

[0168] [Variable interval data]

[0169] [Lens group data]

[0170] Figure 8 1 and 10 are diagrams of various aberrations when the optical system of Example 4 is in infinity focus. As can be seen from the diagrams, the optical system of Example 4 has various aberrations corrected well and has excellent imaging performance.

[0171] (Fifth embodiment)

[0172] use Figure 9-10 And Table 5 illustrate the fifth embodiment. Fig. 9: is a diagram showing the lens structure of the optical system of the fifth embodiment. The optical system OL (5) of the fifth embodiment is composed of a first lens group G1 with positive optical focal length, a second lens group G2 with negative optical focal length, a third lens group G3 with positive optical focal length, a fourth lens group G4 with positive optical focal length, and a fifth lens group with negative optical focal length, which are arranged in sequence from the object side along the optical axis. When focusing from an infinitely distant object to a close-up object, the second lens group G2 and the fourth lens group G4 move along the optical axis, specifically, the second lens group G2 moves toward the image plane side, and the fourth lens group G4 moves toward the object side, and the intervals between adjacent lens groups change. In addition, when focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed relative to the image plane I.

[0173] The second lens group G2 as the first focusing group is arranged on the object side of the aperture stop S. During focusing, the position of the aperture stop S is fixed relative to the image plane I. In this embodiment, the aperture stop S is arranged between the second lens group G2 and the third lens group G3.

[0174] The first lens group G1 is composed of a positive meniscus lens L11 with a convex surface facing the object side, a cemented lens formed by cementing a biconvex positive lens L12 and a biconcave negative lens L13, and a positive meniscus lens L14 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The lens surface on the object side of the positive meniscus lens L14 is an aspherical surface. In addition, the lens L11 of the first lens group G1 is a lens that satisfies the above-mentioned conditional expressions (12) and (13).

[0175] The second lens group G2 is composed of a negative meniscus lens L21 with a convex surface facing the object side. When focusing, the second lens group G2 moves along the optical axis toward the image plane I. An aperture stop S is arranged on the image side of the second lens group G2.

[0176] The third lens group G3 is composed of a cemented lens formed by a biconcave negative lens L31 and a biconvex positive lens L32 arranged in sequence along the optical axis from the object side, a cemented lens formed by a biconcave negative lens L33 and a positive meniscus lens L34 with a convex surface facing the object side, and a biconvex positive lens L35.

[0177] The fourth lens group G4 is composed of a cemented lens composed of a negative meniscus lens L41 and a positive meniscus lens L42 arranged in order from the object side along the optical axis. When focusing, the fourth lens group G4 moves along the optical axis toward the object side.

[0178] The fifth lens group G5 is composed of a cemented lens formed by cementing a biconvex positive lens L51 and a biconcave negative lens L52 arranged in sequence from the object side along the optical axis, and a negative meniscus lens L53 with a convex surface facing the image side. The lens surface on the object side of the negative meniscus lens L53 is an aspherical surface. An image surface I is arranged on the image side of the fifth lens group G5. In addition, the lens L51 of the fifth lens group G5 is a lens that satisfies the above-mentioned conditional expressions (14) and (15).

[0179] Table 5 below lists the values ​​of the parameters of the optical system of Example 5.

[0180] (Table 5)

[0181] [Overall parameters]

[0182] [Lens parameters]

[0183] [Aspherical surface data]

[0184] [Variable interval data]

[0185] [Lens group data]

[0186] Fig.10 1 and 10 are diagrams of various aberrations when the optical system of Example 5 is in infinity focus. As can be seen from the diagrams, the optical system of Example 5 has various aberrations corrected well and has excellent imaging performance.

[0187] Next, a table of [conditional expression corresponding values] is shown below. In this table, values ​​corresponding to the conditional expressions (1) to (17) are collectively shown as Ex1 to Ex5 for all the examples (first to fifth examples).

[0188] Conditional formula (1) 0.50<f1 / f3<2.00

[0189] Conditional formula (2) 0.30<(-f2) / f3<2.00

[0190] Conditional formula (3) 1.10<f4 / f3<2.60

[0191] Conditional formula (4) 0.35<(-f5) / f3<2.50

[0192] Conditional expression (5) 0.30<D1 / D3<2.00

[0193] Conditional expression (6) 0.01<D2 / D3<0.20

[0194] Conditional expression (7) 0.01<D4 / D3<1.00

[0195] Conditional expression (8) 0.01<D5 / D3<1.50

[0196] Conditional formula (9) 0.05<(-f2) / f4<1.40

[0197] Conditional expression (10) 0.25<Mv2 / Mv4<1.35

[0198] Conditional formula (11) 1.00<β2 / β4<10.00

[0199] Conditional formula (12) 1.80<nd1

[0200] Conditional formula (13) 17.00<νd1<35.00

[0201] Conditional formula (14) 1.80<nd2

[0202] Conditional formula (15) 17.00<νd2<35.00

[0203] Conditional formula (16) 1.00<(L1r1+L1r2) / (L1r2-L1r1)<9.00

[0204] Conditional formula (17) 5.00°<ω<16.00°

[0205] [Conditional Expression Corresponding Value] (1st to 5th Embodiments)

[0206] According to the above-described embodiments, it is possible to realize an optical system that is bright and has excellent optical performance.

[0207] The above-mentioned embodiments are specific examples of the present invention, and the present invention is not limited thereto.

[0208] The following contents can be appropriately adopted within the range not impairing the optical performance of the optical system of this embodiment.

[0209] As an example of the optical system of this embodiment, an optical system with a 5-group structure is shown, but the present application is not limited thereto, and an optical system with other group structures (e.g., 6 groups, 7 groups, 8 groups, etc.) may also be formed. Specifically, a structure in which a lens or a lens group is added to the object side or the image side of the optical system of this embodiment. A structure in which a third focusing lens group is added in addition to the two focusing lens groups may also be used. In addition, a lens group refers to a portion having at least one lens separated by an air gap that changes during focusing.

[0210] A lens group or part of a lens group may be used as an anti-shake lens group, which moves in a direction having a component perpendicular to the optical axis, or rotates and moves (sways) in a plane including the optical axis to correct image shake caused by hand shake.

[0211] The lens surface may be formed by a spherical surface or a flat surface, or may be formed by an aspherical surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment become easy, and degradation of optical performance caused by errors in processing and assembly adjustment can be prevented, so it is preferred. In addition, even in the case of deviation of the image plane, degradation of the image rendering performance is small, so it is preferred.

[0212] When the lens surface is an aspheric surface, the aspheric surface may be any of an aspheric surface based on grinding, a glass molded aspheric surface formed by a mold into an aspheric shape of glass, and a composite aspheric surface formed by a resin on the surface of glass into an aspheric shape. In addition, the lens surface may be a diffraction surface, and the lens may be a distributed refractive index lens (GRIN lens) or a plastic lens.

[0213] The aperture stop is preferably arranged on the image plane side of the second lens group as the first focus lens group, but a member serving as an aperture stop may be omitted and the lens frame may be used instead to perform its function.

[0214] In order to reduce glare and ghosting and achieve high-contrast optical performance, an antireflection film with high transmittance in a wide wavelength range may be applied to each lens surface.

[0215] Description of symbols G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 Lens Group 5 I Image plane S Aperture stop

Claims

1. An optical system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, arranged in order from the object side along an optical axis, During focusing, the second lens group and the fourth lens group move along the optical axis. The optical system satisfies the following conditional formula: 0.50<f1 / f3<2.00 in, f1: focal length of the first lens group, f3: focal length of the third lens group.

2. The optical system according to claim 1, wherein: The optical system satisfies the following conditional formula: 0.30<(-f2) / f3<2.00 Wherein, f2: focal length of the second lens group.

3. The optical system according to claim 1 or 2, wherein: The optical system satisfies the following conditional formula: 1.10<f4 / f3<2.60 Wherein, f4: the focal length of the fourth lens group.

4. The optical system according to any one of claims 1 to 3, wherein: The optical system satisfies the following conditional formula: 0.35<(-f5) / f3<2.50 Wherein, f5 is the focal length of the fifth lens group.

5. The optical system according to any one of claims 1 to 4, wherein: The optical system satisfies the following conditional formula: 0.30<D1 / D3<2.00 Wherein, D1: the length on the optical axis from the lens surface of the first lens group closest to the object side to the lens surface of the first lens group closest to the image plane side, D3: The length on the optical axis from the lens surface of the third lens group that is most object-side to the lens surface of the third lens group that is most image-plane-side.

6. The optical system according to any one of claims 1 to 5, wherein: The optical system satisfies the following conditional formula: 0.01<D2 / D3<0.20 Wherein, D2: the length on the optical axis from the lens surface of the second lens group closest to the object side to the lens surface of the second lens group closest to the image plane side, D3: The length on the optical axis from the lens surface of the third lens group that is most object-side to the lens surface of the third lens group that is most image-plane-side.

7. The optical system according to any one of claims 1 to 6, wherein: The optical system satisfies the following conditional formula: 0.01<D4 / D3<1.00 Wherein, D4: the length on the optical axis from the lens surface of the fourth lens group closest to the object side to the lens surface of the fourth lens group closest to the image plane side, D3: The length on the optical axis from the lens surface of the third lens group that is most object-side to the lens surface of the third lens group that is most image-plane-side.

8. The optical system according to any one of claims 1 to 7, wherein: The optical system satisfies the following conditional formula: 0.01<D5 / D3<1.50 Wherein, D5: the length on the optical axis from the lens surface of the fifth lens group closest to the object side to the lens surface of the fifth lens group closest to the image plane side, D3: The length on the optical axis from the lens surface of the third lens group that is most object-side to the lens surface of the third lens group that is most image-plane-side.

9. The optical system according to any one of claims 1 to 8, wherein: The optical system satisfies the following conditional formula: 0.05<(-f2) / f4<1.40 Wherein, f2: focal length of the second lens group, f4: focal length of the fourth lens group.

10. The optical system according to any one of claims 1 to 9, wherein: The optical system satisfies the following conditional formula: 0.25<Mv2 / Mv4<1.35 Wherein, Mv2: the absolute value of the movement of the second lens group on the optical axis during focusing, Mv4: The absolute value of the movement of the fourth lens group on the optical axis during focusing.

11. The optical system according to any one of claims 1 to 10, wherein: The optical system satisfies the following conditional formula: 1.00＜β2 / β4＜10.00 Wherein, β2: the lateral magnification of the second lens group, β4: the lateral magnification of the fourth lens group.

12. The optical system according to any one of claims 1 to 11, wherein: The second lens group is composed of a single lens.

13. The optical system according to any one of claims 1 to 12, wherein: The fourth lens group is composed of one cemented lens.

14. The optical system according to any one of claims 1 to 13, wherein: The optical system includes an aperture stop disposed on the image side of the second lens unit.

15. The optical system according to any one of claims 1 to 14, wherein: The optical system satisfies the following conditional formula: 1.80<nd1 17.00<νd1<35.00 Wherein, nd1: the refractive index of the lens closest to the object side of the optical system based on the d line, νd1: Abbe number of the lens closest to the object side of the optical system, based on the d-line.

16. The optical system according to any one of claims 1 to 15, wherein: The fifth lens group has at least one lens satisfying the following conditional formula: 1.80<nd2 17.00<νd2<35.00 Wherein, nd2: the refractive index of the lens of the fifth lens group based on the d line, νd2: Abbe number of the lens of the fifth lens group based on the d-line.

17. The optical system according to any one of claims 1 to 16, wherein: The third lens group has at least five lenses.

18. The optical system according to any one of claims 1 to 17, wherein: The third lens group includes at least two cemented lenses.

19. The optical system according to any one of claims 1 to 18, wherein: The optical system satisfies the following conditional formula: 1.00<(L1r1+L1r2) / (L1r2-L1r1)<9.00 Wherein, L1r1: the radius of curvature of the object-side lens surface of the lens closest to the object side of the optical system, L1r2: The radius of curvature of the image-side lens surface of the lens closest to the object side of the optical system.

20. The optical system according to any one of claims 1 to 19, wherein: The optical system satisfies the following conditional formula: 5.00°<ω<16.00° Wherein, ω is the half field angle of the optical system when focusing at infinity.

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

22. A method for manufacturing an optical system, the optical system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, arranged in order from the object side along an optical axis, During focusing, the second lens group (G2) and the fourth lens group (G4) move along the optical axis. The manufacturing method of the optical system comprises the steps of arranging each lens in the lens barrel in a manner satisfying the following conditional expression: 0.50<f1 / f3<2.00 in, f1: focal length of the first lens group, f3: focal length of the third lens group.

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