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

Abstract

To provide an optical system which is lightweight and compact and has excellent optical performance.SOLUTION: The optical system OL consists of, in order from an object, a front group GA, a stop S, and a rear group GB, wherein the front group GA has, in order from the object, a first positive lens L1p, a second positive lens L2p, a third positive lens L3p, and a first negative lens L1n, the first positive lens L1p and the second positive lens L2p are both single lenses, and the following conditional expressions are satisfied: 2.50 <TL / d1 <15.00, where TL is a length on the optical axis from the lens surface closest to the object side of the optical system OL to the image plane, and d1 is a length on the optical axis from the lens surface on the image plane side in the first positive lens L1p to the lens surface on the object side in the second positive lens L2p SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system, an optical instrument, and a method for manufacturing an optical system. [Background technology]

[0002] Conventionally, optical systems suitable for photo cameras, electronic still cameras, video cameras, etc. have been proposed (see, for example, Patent Document 1). Among such optical systems, there is a demand for optical systems that are lightweight and compact yet have various aberrations well corrected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-145731 Summary of the Invention

[0004] An optical system according to a first aspect of the present invention comprises, arranged in order from the object side along an optical axis, a front group, a stop, and a rear group, the front group having, arranged in order from the object side, a first positive lens, a second positive lens, a third positive lens, and a first negative lens, the first positive lens and the second positive lens each being composed of a single lens, and satisfying the following conditional expression: 2.50 <TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

[0005] An optical system according to a second aspect of the present invention comprises, arranged in order from the object side along the optical axis, a front group, a stop, and a rear group, wherein the front group has, arranged in order from the object side, a first positive lens, a second positive lens, a third positive lens, a fourth positive lens, and a first negative lens, wherein the first positive lens, the second positive lens, and the third positive lens are all composed of single lenses, and satisfies the following conditional expression: 2.50 <TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

[0006] An optical device according to the present invention includes the optical system described above.

[0007] A method for manufacturing an optical system according to the present invention includes arranging, in a lens barrel, a front group, a stop, and a rear group, which are arranged in order from the object side along an optical axis, and the front group has, in order from the object side, a first positive lens, a second positive lens, a third positive lens, and a first negative lens, and the first positive lens and the second positive lens are both single lenses, and are configured to satisfy the following conditional expression: 2.50 <TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

[0008] A method for manufacturing an optical system according to the present invention includes arranging, in a lens barrel, a front group, a stop, and a rear group, which are arranged in order from the object side along the optical axis, and the front group has, in order from the object side, a first positive lens, a second positive lens, a third positive lens, a fourth positive lens, and a first negative lens, and the first positive lens, the second positive lens, and the third positive lens are all single lenses, and are configured to satisfy the following conditional expression: 2.50 <TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 2 is a diagram showing the lens configuration of an optical system according to Example 1. [Figure 2] 5A to 5C are diagrams illustrating various aberrations of the optical system according to Example 1 when focused at infinity. [Figure 3] FIG. 10 is a diagram showing the lens configuration of an optical system according to a second example. [Figure 4] 10A to 10C are diagrams showing various aberrations of the optical system according to Example 2 when focused on infinity. [Figure 5] FIG. 10 is a diagram showing the lens configuration of an optical system according to Example 3. [Figure 6] 10A to 10C are diagrams showing various aberrations of the optical system according to Example 3 when focused at infinity. [Figure 7] FIG. 10 is a diagram showing the lens configuration of an optical system according to Example 4. [Figure 8] 10A to 10C are diagrams showing various aberrations of the optical system according to Example 4 when focused on infinity. [Figure 9] FIG. 10 is a diagram showing the lens configuration of an optical system according to Example 5. [Figure 10] 10A to 10C are diagrams illustrating various aberrations of the optical system according to Example 5 when focused on an object at infinity. [Figure 11] FIG. 13 is a diagram showing the lens configuration of an optical system according to Example 6. [Figure 12] 13A to 13C are diagrams illustrating various aberrations of the optical system according to Example 6 when focused at infinity. [Figure 13] FIG. 1 is a diagram showing the configuration of a camera including an optical system according to each embodiment. [Figure 14] 4 is a flowchart showing a method for manufacturing the optical system according to the first embodiment. [Figure 15] 10 is a flowchart showing a method for manufacturing an optical system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will now be described. First, a camera (optical device) equipped with an optical system according to each embodiment will be described with reference to FIG. 13. As shown in FIG. 13, this camera 1 is composed of a main body 2 and a photographic lens 3 attached to the main body 2. The main body 2 is equipped with an image sensor 4, a main body control unit (not shown) that controls the operation of the digital camera, and an LCD screen 5. The photographic lens 3 is equipped with an optical system OL consisting of multiple lens groups, and a lens position control mechanism (not shown) that controls the position of each lens group. The lens position control mechanism is composed of a sensor that detects the position of the lens groups, a motor that moves the lens groups back and forth along the optical axis, a control circuit that drives the motor, etc.

[0011] Light from the subject is collected by the optical system OL of the photographing lens 3 and reaches the image plane I of the image sensor 4. The light from the subject that reaches the image plane I is photoelectrically converted by the image sensor 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 in response to a user operation. Note that this camera may be a mirrorless camera or a single-lens reflex camera with a quick-return mirror. Also, the optical system OL shown in FIG. 7 is a schematic representation of an optical system provided in the photographing lens 3, and the lens configuration of the optical system OL is not limited to this configuration.

[0012] Next, an optical system according to the first embodiment will be described. As shown in Fig. 1, an optical system OL(1) as an example of the optical system OL according to the first embodiment is composed of, in order from the object side along the optical axis, a front group GA, a stop S, and a rear group GB. The front group has, in order from the object side, a first positive lens L1p, a second positive lens L2p, a third positive lens L3p, and a first negative lens L1n. The first positive lens L1p and the second positive lens L2p are both single lenses, and satisfy the following conditional formula (1A). In this specification, the term "lens component" is used to mean both "single lenses and cemented lenses."

[0013] 2.50 <TL / d1<15.00 ···(1A) where TL is the distance on the optical axis from the lens surface closest to the object in the optical system OL to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens L1p on the image plane side to the lens surface of the second positive lens L2p on the object side

[0014] According to this embodiment, it is possible to obtain an optical system that is lightweight and compact yet has well-corrected axial chromatic aberration, and an optical apparatus that includes this optical system. The optical system OL according to this embodiment may be the optical system OL(2) shown in Fig. 3, the optical system OL(3) shown in Fig. 5, the optical system OL(4) shown in Fig. 7, the optical system OL(5) shown in Fig. 9, or the optical system OL(6) shown in Fig. 11.

[0015] Conditional formula (1A) defines an appropriate relationship between the overall length of the optical system OL and the distance on the optical axis between the first positive lens L1p and the second positive lens L2p. By satisfying conditional formula (1A), the effect of correcting axial chromatic aberration can be more reliably achieved.

[0016] If the corresponding value of conditional formula (1A) exceeds the upper limit, it becomes difficult to effectively correct axial chromatic aberration, etc. By setting the upper limit of conditional formula (1A) to 13.60, 12.20, 10.80, 9.40, or even 8.00, the effect of this embodiment can be further ensured.

[0017] If the corresponding value of conditional formula (1A) falls below the lower limit, the mass of the lens increases, making it difficult to reduce the weight of the optical system. By setting the lower limit of conditional formula (1A) to 2.70, 2.90, 3.10, 3.30, or even 3.50, the effect of this embodiment can be further ensured.

[0018] In the optical system OL according to this embodiment, the following conditional expression (2) may be satisfied. 0.40 <d1 / d2<5.00 ···(2) where d2 is the distance on the optical axis from the lens surface of the second positive lens L2p on the image plane side to the lens surface of the third positive lens on the object side.

[0019] Conditional expression (2) defines appropriate ranges for the distance between the first positive lens L1p and the second positive lens L2p and the distance between the second positive lens L2p and the third positive lens L3p. By satisfying conditional expression (2), the effect of this embodiment, which corrects each aberration while reducing the weight of the optical system, can be more reliably achieved.

[0020] If the corresponding value of conditional expression (2) exceeds the upper limit, it becomes difficult to correct axial chromatic aberration and spherical aberration. By setting the upper limit of conditional expression (2) to 4.70, 4.40, 4.10, 3.80, or even 3.50, the effect of this embodiment can be further ensured.

[0021] If the corresponding value of conditional expression (2) is below the lower limit, the diameter of the second positive lens L2p increases, which increases the weight of the lens and makes it difficult to make the optical system lightweight. By setting the lower limit of conditional expression (2) to 0.47, 0.54, 0.61, 0.68, or even 0.75, the effect of this embodiment can be made more certain.

[0022] Next, an optical system according to the second embodiment will be described. As shown in Fig. 5, an optical system OL(3) as an example of the optical system OL according to the second embodiment is composed of, in order from the object side along the optical axis, a front group GA, a stop S, and a rear group GB, and the front group has, in order from the object side, a first positive lens L1p, a second positive lens L2p, a third positive lens L3p, a fourth positive lens L4p, and a first negative lens L1n, and the first positive lens L1p, the second positive lens L2p, and the third positive lens L3p are all composed of single lenses, and satisfy the following conditional formula (1B):

[0023] 2.50 <TL / d1<15.00 ···(1B) where TL is the distance on the optical axis from the lens surface closest to the object in the optical system OL to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens L1p on the image plane side to the lens surface of the second positive lens L2p on the object side

[0024] According to this embodiment, it is possible to obtain an optical system that is lightweight and compact yet has excellent correction for axial chromatic aberration, and an optical apparatus that includes this optical system. The optical system OL according to this embodiment may be the optical system OL(6) shown in FIG.

[0025] Conditional formula (1B) defines an appropriate relationship between the overall length of the optical system OL and the distance on the optical axis between the first positive lens L1p and the second positive lens L2p. By satisfying conditional formula (1B), it is possible to achieve a lightweight optical system and to effectively correct axial chromatic aberration and the like.

[0026] If the corresponding value of conditional expression (1B) exceeds the upper limit, it becomes difficult to effectively correct axial chromatic aberration, etc. By setting the upper limit of conditional expression (1B) to 13.60, 12.20, 10.80, 9.40, or even 8.00, the effect of this embodiment can be further ensured.

[0027] If the corresponding value of conditional formula (1B) is below the lower limit, the mass of the lens increases, making it difficult to reduce the weight of the optical system. By setting the lower limit of conditional formula (1B) to 2.70, 2.90, 3.10, 3.30, or even 3.50, the effect of this embodiment can be further ensured.

[0028] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (3). 1.00 <d1 / d3<8.00 ···(3) where d3 is the distance on the optical axis from the lens surface of the third positive lens L3p on the image plane side to the lens surface of the fourth positive lens L4p on the object side.

[0029] Conditional expression (3) defines appropriate ranges for the distance between the first positive lens L1p and the second positive lens L2p, and the distance between the third positive lens L3p and the fourth positive lens L4p. By satisfying conditional expression (3), the weight of the optical system can be reduced.

[0030] If the corresponding value of conditional expression (3) exceeds the upper limit, it becomes difficult to correct axial chromatic aberration and spherical aberration. By setting the upper limit of conditional expression (3) to 7.60, 7.20, 6.80, 6.40, or even 6.00, the effect of this embodiment can be further ensured.

[0031] If the value corresponding to conditional expression (3) falls below the lower limit, the weight of the lens increases, making it difficult to make the optical system lightweight. By setting the lower limit of conditional expression (3) to 1.12, 1.24, 1.36, 1.48, or even 1.60, the effect of this embodiment can be further ensured.

[0032] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (4). 2.00 <f / d1<16.00 ···(4) where f is the focal length of the entire optical system (OL)

[0033] Conditional expression (4) defines an appropriate range for the focal length of the entire optical system OL and the distance between the first positive lens L1p and the second positive lens L2p. By satisfying conditional expression (4), it is possible to reduce the lens mass and to effectively correct spherical aberration.

[0034] If the value corresponding to conditional expression (4) exceeds the upper limit, the mass of the lens increases, making it difficult to reduce the weight of the optical system. By setting the upper limit of conditional expression (4) to 15.00, 14.50, 14.00, 13.50, 13.00, or even 12.50, the effect of this embodiment can be further ensured.

[0035] If the corresponding value of conditional expression (4) falls below the lower limit, it becomes difficult to effectively correct spherical aberration. By setting the lower limit of conditional expression (4) to 2.40, 2.80, 3.20, 3.60, or even 4.00, the effect of this embodiment can be further ensured.

[0036] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (5). 0.20 <fp12 / f<1.00 ···(5) where fp12 is the combined focal length of the first positive lens L1p and the second positive lens L2p f: focal length of the entire optical system

[0037] Conditional expression (5) defines an appropriate range for the combined focal length of the first positive lens L1p and the second positive lens L2, and the focal length of the entire optical system OL. By satisfying conditional expression (5), a reduction in the weight of the optical system can be achieved, and spherical aberration can be effectively corrected.

[0038] If the value corresponding to conditional expression (5) exceeds the upper limit, it becomes difficult to effectively correct spherical aberration. By setting the upper limit of conditional expression (5) to 0.92, 0.84, 0.76, 0.68, or even 0.60, the effect of this embodiment can be further ensured.

[0039] If the corresponding value of conditional expression (5) falls below the lower limit, the mass of the lens increases, making it difficult to reduce the weight of the optical system. By setting the lower limit of conditional expression (5) to 0.24, 0.28, 0.32, 0.36, or even 0.40, the effect of this embodiment can be further ensured.

[0040] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (6). 0.05 <fp123 / f<0.60 ···(6) where fp123 is the composite focal length of the first positive lens L1p, the second positive lens L2p, and the third positive lens L3p. f: focal length of the entire optical system

[0041] Conditional expression (6) defines an appropriate range for the combined focal length of the first positive lens L1p, the second positive lens L2p, and the third positive lens L3p, and the focal length of the entire optical system OL. By satisfying conditional expression (6), a reduction in the weight of the optical system can be achieved, and spherical aberration can be effectively corrected.

[0042] If the corresponding value of conditional expression (6) exceeds the upper limit, it becomes difficult to effectively correct spherical aberration. By setting the upper limit of conditional expression (6) to 0.57, 0.54, 0.51, 0.48, or even 0.45, the effect of this embodiment can be further ensured.

[0043] If the value corresponding to conditional expression (6) falls below the lower limit, the mass of the lens increases, making it difficult to make the optical system lightweight. By setting the lower limit of conditional expression (6) to 0.08, 0.11, 0.14, 0.17, or even 0.20, the effect of this embodiment can be further ensured.

[0044] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (7): 0.50 <fA / BF<6.00 ···(7) However, fA: focal length of the front group GA BF: The distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane

[0045] Condition (7) defines an appropriate range for the focal length of the front group GA and the distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane (i.e., back focus). Satisfying condition (7) enables good correction of coma.

[0046] If the corresponding value of conditional expression (7) exceeds the upper limit, it becomes difficult to effectively correct coma. By setting the upper limit of conditional expression (7) to 5.50, 5.00, 4.50, 4.00, or even 3.50, the effect of this embodiment can be further ensured.

[0047] If the corresponding value of conditional expression (7) falls below the lower limit, it becomes difficult to effectively correct coma. By setting the lower limit of conditional expression (7) to 0.80, 1.10, 1.40, 1.70, or even 1.85, the effect of this embodiment can be further ensured.

[0048] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (8). 0.80<(-fB) / BF<2.50 (8) However, fB is the focal length of the rear group GB. BF: The distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane

[0049] Conditional expression (8) defines an appropriate range for the focal length of the rear group GB and the distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane (i.e., back focus). By satisfying conditional expression (8), the refractive power of the rear group becomes strong, the exit pupil becomes close, and the optical system can be made lighter.

[0050] If the value corresponding to conditional expression (8) exceeds the upper limit, the mass of the lens increases, making it difficult to reduce the weight of the optical system. By setting the upper limit of conditional expression (8) to 2.45, 2.40, 2.30, 2.20, or even 2.10, the effect of this embodiment can be further ensured.

[0051] If the corresponding value of conditional expression (8) falls below the lower limit, it becomes difficult to correct lateral chromatic aberration, distortion, etc. By setting the lower limit of conditional expression (8) to 0.84, 0.88, 0.92, 0.96, or even 1.00, the effect of this embodiment can be further ensured.

[0052] In the optical system OL according to this embodiment, it is preferable to satisfy the following conditional expression (9). 3.50 <fp1 / BF<10.00 ···(9) However, fp1 is the focal length of the first positive lens L1p. BF: The distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane

[0053] Conditional expression (9) defines an appropriate range for the focal length of the first positive lens L1p and the distance on the optical axis from the lens surface closest to the image plane in the optical system OL to the image plane, i.e., the back focus. Satisfying conditional expression (9) enables good correction of lateral chromatic aberration, coma, and other aberrations.

[0054] If the corresponding value of conditional expression (9) exceeds the upper limit, it becomes difficult to effectively correct coma. By setting the upper limit of conditional expression (9) to 9.40, 8.80, 8.20, 7.60, or even 7.00, the effect of this embodiment can be further ensured.

[0055] If the corresponding value of conditional expression (9) falls below the lower limit, it becomes difficult to effectively correct lateral chromatic aberration. By setting the lower limit of conditional expression (9) to 3.70, 3.90, 4.10, 4.30, or even 4.50, the effect of this embodiment can be further ensured.

[0056] In the optical system OL according to this embodiment, the following conditional expression (10) may be satisfied. 0.80 <fA / (-fB)<5.00 ···(10) However, fA: focal length of the front group GA fB: Focal length of rear group GB

[0057] Conditional expression (10) defines an appropriate range for the focal length of the front group GA and the focal length of the rear group GB. By satisfying conditional expression (10), the effect of this embodiment can be more reliably achieved.

[0058] If the corresponding value of conditional expression (10) exceeds the upper limit, it becomes difficult to effectively correct distortion. By setting the upper limit of conditional expression (10) to 4.60, 4.20, 3.80, 3.40, or even 3.00, the effect of this embodiment can be further ensured.

[0059] If the corresponding value of conditional expression (10) falls below the lower limit, it becomes difficult to reduce the size of the optical system. By setting the lower limit of conditional expression (10) to 0.86, 0.92, 0.98, 1.04, or even 1.10, the effect of this embodiment can be further ensured.

[0060] In the optical system OL according to this embodiment, the following conditional expression (11) may be satisfied. 0.10 <fA / f<0.80 ···(11) However, fA: focal length of the front group GA f: focal length of the entire optical system

[0061] Conditional expression (11) defines an appropriate range for the focal length of the front group GA and the focal length of the entire optical system OL. By satisfying conditional expression (11), the effect of this embodiment can be more reliably achieved.

[0062] If the corresponding value of conditional expression (11) exceeds the upper limit, it becomes difficult to reduce the size of the optical system. By setting the upper limit of conditional expression (11) to 0.74, 0.68, 0.62, 0.56, or even 0.50, the effect of this embodiment can be further ensured.

[0063] If the corresponding value of conditional expression (11) falls below the lower limit, it becomes difficult to correct axial chromatic aberration. By setting the lower limit of conditional expression (11) to 0.16, 0.22, 0.28, 0.34, or even 0.40, the effect of this embodiment can be further ensured.

[0064] In the optical system OL according to this embodiment, the following conditional expression (12) may be satisfied. 0.10<(-fB) / f<0.70 (12) However, fB is the focal length of the rear group GB. f: focal length of the entire optical system

[0065] Conditional expression (12) defines an appropriate range for the focal length of the rear group GB and the focal length of the entire optical system OL. By satisfying conditional expression (12), the effects of this embodiment can be more reliably achieved.

[0066] If the corresponding value of conditional expression (12) exceeds the upper limit, it becomes difficult to reduce the size of the optical system. By setting the upper limit of conditional expression (12) to 0.64, 0.58, 0.52, 0.46, or even 0.42, the effect of this embodiment can be further ensured.

[0067] If the corresponding value of conditional expression (12) falls below the lower limit, it becomes difficult to correct longitudinal chromatic aberration. By setting the lower limit of conditional expression (12) to 0.12, 0.13, 0.14, 0.15, or even 0.16, the effect of this embodiment can be further ensured.

[0068] In the optical system OL according to this embodiment, the following conditional expression (13) may be satisfied. 0.10 <TL / f<1.00 ···(13) where TL is the distance on the optical axis from the lens surface closest to the object in the optical system OL to the image plane. f: focal length of the entire optical system

[0069] Condition (13) defines an appropriate range for the overall length of the optical system OL and the focal length of the entire optical system OL. By satisfying condition (13), the optical system can be made compact.

[0070] If the corresponding value of conditional expression (13) exceeds the upper limit, it becomes difficult to reduce the size of the optical system. By setting the upper limit of conditional expression (13) to 0.97, 0.94, 0.91, 0.88, or even 0.85, the effect of this embodiment can be further ensured.

[0071] If the corresponding value of conditional expression (13) falls below the lower limit, the mass of the optical system increases and correction of lateral chromatic aberration and distortion becomes difficult. By setting the lower limit of conditional expression (13) to 0.18, 0.26, 0.34, 0.42, or even 0.50, the effect of this embodiment can be further ensured.

[0072] In the optical system OL according to this embodiment, the following conditional expressions (14) and (15) may be satisfied. ndL1p<1.60 (14) 60.00<νdL1p ···(15) where ndL1p is the refractive index of the first positive lens L1p for the d line νdL1p: Abbe number of the first positive lens L1p based on the d line

[0073] Conditional expression (14) defines an appropriate range for the refractive index of the first positive lens L1p for the d-line. By satisfying conditional expression (14), the weight of the optical system can be reduced.

[0074] If the value corresponding to conditional expression (14) exceeds the upper limit, it becomes difficult to reduce the weight of the optical system. By setting the upper limit of conditional expression (14) to 1.55, or even 1.50, the effect of this embodiment can be made even more certain.

[0075] The effect of this embodiment can be further ensured by setting the lower limit of conditional expression (14) to 1.00. To further ensure the effect of this embodiment, the lower limit of conditional expression (14) may be set to 1.35, 1.40, or even 1.45.

[0076] Conditional expression (15) defines an appropriate range for the Abbe number of the first positive lens L1p with respect to the d-line. By satisfying conditional expression (15), lateral chromatic aberration and the like can be corrected well.

[0077] If the corresponding value of conditional expression (15) falls below the lower limit, it becomes difficult to correct lateral chromatic aberration. By setting the lower limit of conditional expression (15) to 70.00, or even 80.00, the effect of this embodiment can be further ensured.

[0078] The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (15) to 90.00. To further ensure the effect of this embodiment, the lower limit of conditional expression (15) may be set to 85.00.

[0079] In the optical system OL according to this embodiment, the following conditional expression (16) may be satisfied. 60.00<νdLrn ···(16) where νdLrn is the Abbe number, based on the d-line, of the negative lens Lrn that is located closest to the image plane among the negative lenses in the optical system OL.

[0080] Condition (16) defines an appropriate range of the Abbe number, based on the d-line, of the negative lens Lrn, which is located closest to the image plane among the negative lenses in the optical system OL. By satisfying condition (16), lateral chromatic aberration and the like can be effectively corrected.

[0081] If the corresponding value of conditional expression (16) falls below the lower limit, it becomes difficult to correct lateral chromatic aberration. By setting the lower limit of conditional expression (16) to 70.00, or even 80.00, the effect of this embodiment can be further ensured.

[0082] The effect of this embodiment can be further ensured by setting the upper limit of conditional expression (16) to 90.00. To further ensure the effect of this embodiment, the lower limit of conditional expression (16) may be set to 88.00, 86.00, or even 84.00.

[0083] In the optical system OL according to this embodiment, the rear group GB may be configured to include at least two cemented lenses. By configuring the rear group GB to include at least two cemented lenses, chromatic aberration of magnification can be effectively corrected.

[0084] In the optical system OL according to this embodiment, a vibration-reduction lens group Gvr that corrects the image formed on the image plane by moving in a direction perpendicular to the optical axis may be disposed adjacent to the diaphragm S. By disposing the vibration-reduction lens group Gvr adjacent to the diaphragm S, it is possible to effectively correct field curvature.

[0085] In the optical system OL according to this embodiment, the front group GA includes a focusing lens group that moves during focusing, and the focusing lens group may be composed of a single lens component. This configuration allows the optical system to be made lighter.

[0086] In the optical system OL according to this embodiment, the rear group GB may have negative refractive power, which allows the entire optical system to be made compact.

[0087] Here, a manufacturing method of the optical system OL according to the first embodiment will be described with reference to FIG. 14. First, a front group, a diaphragm, and a rear group are arranged in order from the object side along the optical axis (step ST11). Then, the front group is configured to have, in order from the object side, a first positive lens, a second positive lens, a third positive lens, and a first negative lens (step ST12). Furthermore, both the first positive lens and the second positive lens are configured as single lenses (step ST13). Then, the lenses are arranged in the lens barrel so as to satisfy at least the above conditional formula (1A) (step ST14). This manufacturing method makes it possible to manufacture an optical system that is lightweight and compact yet has various aberrations well corrected.

[0088] Next, a manufacturing method of the optical system OL according to the second embodiment will be described with reference to FIG. 15. First, a front group, a diaphragm, and a rear group are arranged in order from the object side along the optical axis (step ST21). Then, the front group is configured to have, in order from the object side, a first positive lens, a second positive lens, a third positive lens, a fourth positive lens, and a first negative lens (step ST22). Furthermore, the first positive lens, the second positive lens, and the third lens are all configured as single lenses (step ST23). Then, the lenses are arranged in the lens barrel so as to satisfy at least the above conditional formula (1B) (step ST24). This manufacturing method makes it possible to manufacture an optical system that is lightweight and compact yet has various aberrations well corrected. [Example]

[0089] Optical systems OL according to examples of this embodiment will be described below with reference to the drawings. Figs. 1, 3, 5, 7, 9, and 11 are cross-sectional views showing the configurations of optical systems OL {OL(1) to OL(6)} according to first to sixth examples. In Figs. 1, 3, 5, 7, 9, and 11, the direction of movement of each lens group along the optical axis when focusing from infinity to a close-distance object is indicated by an arrow accompanied by the word (focusing). The direction of movement of the vibration-reduction lens group Gvr is also indicated by an arrow accompanied by the word (vibration reduction).

[0090] 1, 3, 5, 7, 9, and 11, the lens groups are represented by the symbols first lens group G1, second lens group G2, front group GA, and rear group GB, and each lens is represented by a number along with the symbol L, but each example represents a lens group independently, etc. Therefore, even if the same symbols are used between examples, this does not mean that the examples have the same configuration.

[0091] Tables 1 to 6 are shown below, which respectively show the data of the various specifications in Examples 1 to 6. In each example, the d-line (λ=587.6 nm) and g-line (λ=435.8 nm) are selected as the targets for calculating aberration characteristics.

[0092] In the [Overall Specifications] table, f is the focal length of the entire optical system, FNO is the F-number, ω is the half angle of view (unit: °), and Y is the image height. TL is the total length of the optical system, and more specifically, it is the value obtained by adding the air-equivalent distance from the final lens surface on the optical axis to the image plane I when focused at infinity to the distance from the final lens surface on the optical axis to the image plane I when focused at infinity. BF is the air-equivalent distance (back focus) from the final lens surface on the optical axis to the image plane I when focused at infinity. In addition, fp1 is the focal length of the first positive lens Lp1, fp12 is the composite focal length of the first positive lens Lp1 and the second positive lens Lp2, and fp123 is the composite focal length of the first positive lens Lp1, the second positive lens Lp2, and the third positive lens Lp3.

[0093] In the [Lens Specifications] table, the surface number indicates the order of the optical surface from the object side along the direction of light ray travel, R is the radius of curvature of each optical surface (surfaces whose center of curvature is located on the image plane side have a positive value), D is the surface spacing, which is the distance on the optical axis from each optical surface to the next optical surface (or image plane), and nd is the refractive index of the optical component material based on the d-line. The "∞" in the radius of curvature indicates a plane or an aperture, and (stop S) indicates an aperture stop. The refractive index of air, nd=1.00000, is omitted.

[0094] The "Variable Distance Data" table shows the surface spacings listed for the surface numbers in the "Lens Specifications" table that have a "variable" surface spacing, and also shows the surface spacings when focused at infinity and when focused at close distances. Note that f represents the focal length of the entire lens system, and β represents the magnification. Also, D0 represents the distance from the object to the optical surface closest to the object in the optical system.

[0095] The [Lens Group Data] table shows the starting surface (the surface closest to the object) and focal length of each lens group.

[0096] In the following, for all specifications, the focal length, radius of curvature R, surface spacing D, and other lengths are generally expressed in "mm" unless otherwise specified, but this is not limited to this, as the same optical performance can be obtained even when the optical system is proportionally enlarged or reduced.

[0097] The explanation of the tables up to this point is common to all the embodiments, and duplicate explanations will be omitted below.

[0098] (First Example) Example 1 will be described with reference to Fig. 1, Fig. 2, and Table 1. Fig. 1 is a diagram showing the lens configuration of an optical system according to Example 1. The optical system OL(1) according to Example 1 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0099] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconvex positive lens L11, a meniscus positive lens L12 with its convex surface facing the object side, a biconvex positive lens L13, a cemented lens of a biconcave negative lens L14 and a biconvex positive lens L15, a cemented lens of a biconcave negative lens L16 and a meniscus positive lens L17 with its convex surface facing the object side, a meniscus negative lens L18 with its convex surface facing the object side, and a meniscus positive lens L19 with its convex surface facing the object side. When focusing from an object at infinity to a close object, the positive lens L19 moves toward the object side.

[0100] The second lens group G2 is composed of a cemented lens of a meniscus positive lens L21 with its convex surface facing the image side and a biconcave negative lens L22, a biconcave negative lens L23, a biconvex positive lens L24, a cemented lens of a biconvex positive lens L25 and a biconcave negative lens L26, a cemented lens of a biconvex positive lens L27 and a biconcave negative lens L28, and a biconvex positive lens L29.

[0101] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0102] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, and the negative lens L14 corresponds to the first negative lens L1n. The negative lens L28 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(1). The positive lens L19 constitutes a focusing lens group that moves when focusing from an object at infinity to an object at a close distance. The positive lens L21 and the cemented lens of the negative lens L22 and the negative lens L23 in the second lens group G2 constitute a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0103] Table 1 below shows the values ​​of the specifications in the optical system according to the first example.

[0104] (Table 1) [Overall specifications] f=497.01 FNO=4.12 2ω=2.45 Y=21.63 TL=410.000 BF=97.938 fp1=446.371 fp12=226.616 fp123=129.955 [Lens specifications] Surface number RD nd νd 1 233.5508 11.494 1.49700 81.61 2 -4353.8430 110.008 3 85.1334 10.250 1.43384 95.16 4 190.1286 34.932 5 97.3608 10.884 1.43384 95.16 6 -242.1276 0.100 7 -285.5727 2.557 1.80610 40.97 8 101.7686 8.422 1.66382 27.35 9 -454.5738 0.100 10 -464.5972 2.348 1.61266 44.46 11 71.6234 7.325 1.43700 95.10 12 334.4228 16.893 13 66.4298 1.766 1.92286 20.88 14 47.9926 Variable (D14) 15 61.5459 5.625 1.56732 42.58 16 242.7061 Variable (D16) 17 ∞ 2.500 (Aperture) 18 -1446.3900 4.070 1.94595 17.98 19 -96.1471 1.188 1.87071 40.73 20 60.6093 3.014 21 -85.2853 1.145 2.00100 29.12 22 744.3350 2.240 23 178.5829 4.677 1.72047 34.71 24 -84.5861 1.785 25 60.5633 6.390 1.61293 36.94 26 -49.0103 1.300 1.94595 17.98 27 100.3529 18.182 28 212.6621 6.102 2.00069 25.46 29 -57.9355 1.500 1.49782 82.57 30 55.5438 2.012 31 219.2245 3.996 1.74077 27.74 32 -386.1577 BF [Variable Interval Data] Infinity focus Close focus f=497.01 β=0.130 D0 ∞ 3698.68 D14 25.250 7.290 D16 4.010 21.970 [Lens group data] Group starting plane focal length G1 1 229.73 G2 18 -204.46

[0105] FIG. 2 shows various aberration diagrams of the optical system according to Example 1 when focused at infinity. In each aberration diagram, FNO indicates the F-number, and Y indicates the image height. In each aberration diagram when focused at infinity, Y indicates the image height. In addition, in each aberration diagram, d indicates the aberration at the d-line (λ=587.6 nm), and g indicates the aberration at the g-line (λ=435.8 nm). In addition, in the aberration diagrams showing the curvature of field, the solid line indicates the sagittal image plane, and the dashed line indicates the meridional image plane. In the distortion diagrams, distortion based on the d-line is shown. Note that the same symbols as in this example are used in the aberration diagrams of each example shown below, and redundant explanations will be omitted.

[0106] From the various aberration diagrams, it can be seen that the optical system according to Example 1 has excellent correction of various aberrations and has excellent imaging performance.

[0107] (Second Example) Example 2 will be described with reference to Figs. 3, 4, and Table 2. Fig. 3 is a diagram showing the lens configuration of an optical system according to Example 2. The optical system OL(2) according to Example 2 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0108] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L11, a meniscus positive lens L12 with its convex surface facing the object side, a cemented lens of a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens of a meniscus positive lens L15 with its convex surface facing the object side and a meniscus negative lens L16 with its convex surface facing the object side, a biconvex positive lens L17, a cemented lens of a meniscus negative lens L18 with its convex surface facing the object side and a plano-convex positive lens L19 with its convex surface facing the object side, a meniscus negative lens L20 with its convex surface facing the object side, and a cemented lens of a meniscus negative lens L21 with its convex surface facing the object side and a meniscus positive lens L22 with its convex surface facing the object side. When focusing from an object at infinity to an object at a close distance, the negative lens L20 moves toward the image plane.

[0109] The second lens group G2 is composed of a cemented lens of a biconvex positive lens L25 and a biconcave negative lens L26, a biconcave negative lens L27, a biconvex positive lens L28, a cemented lens of a biconvex positive lens L29 and a biconcave negative lens L30, a cemented lens of a biconvex positive lens L31 and a biconcave negative lens L32, and a cemented lens of a biconvex positive lens L33 and a plano-concave negative lens L34 with its concave surface facing the object side.

[0110] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0111] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, and the negative lens L14 corresponds to the first negative lens L1n. The negative lens L34 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(2). The negative lens L20 constitutes a focusing lens group that moves when focusing from an object at infinity to a close object. The cemented lens of the positive lens L25 and the negative lens L26 in the second lens group G2, together with the negative lens L27, constitutes a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0112] Table 2 below shows the values ​​of the specifications in the optical system according to the second example.

[0113] (Table 2) [Overall specifications] f=497.01 FNO=4.12 2ω=2.45 Y=21.63 TL=340,000 BF=67.153 fp1=450.000 fp12=214.506 fp123=115.970 [Lens specifications] Surface number RD nd νd 1 236.5546 11.564 1.48749 70.32 2 -2971.4604 40.685 3 110.6766 12.590 1.43384 95.16 4 344.1658 52.303 5 70.5324 13.129 1.43384 95.16 6 -828.7641 2.728 1.73211 46.18 7 58.3373 2.000 8 51.8599 12.719 1.43700 95.10 9 21864.1404 2.357 1.74950 35.25 10 120.6369 11.391 11 76.2408 7.638 1.80518 25.45 12 -2127.3667 1.000 13 1629.6054 1.961 1.73211 46.18 14 34.3249 10.583 1.43700 95.10 15 0.0000 Variable (D15) 16 130.2437 2.000 1.60738 56.74 17 51.2877 Variable (D17) 18 59.0814 1.161 1.92286 20.88 19 25.0326 6.640 1.85000 27.03 20 180.3928 1.986 21 ∞ 1.500 (Aperture) 22 180.2820 4.329 1.94595 17.98 23 -110.6291 1.064 1.87071 40.73 24 47.3532 2.714 25 -92.2864 1.016 1.87071 40.73 26 73.3478 2.722 27 50.0265 5.252 1.60342 38.03 28 -139.3328 0.100 29 37.6301 5.828 1.78472 25.64 30 -135.5464 1.000 1.94595 17.98 31 33.4331 7.429 32 82.7847 7.837 1.68376 37.64 33 -22.7712 1.500 1.78590 44.17 34 40.6472 0.100 35 40.4951 9.6118 1.68376 37.64 36 -25.2785 1.500 1.49782 82.57 37∞BF [Variable Interval Data] Infinity focus Close focus f=497.01 β=0.130 D0 ∞ 3763.08 D15 3.000 21.350 D17 21.910 3.560 [Lens group data] Group starting plane focal length G1 1 210.87 G2 22 -85.02

[0114] 4 shows diagrams of various aberrations when the optical system according to Example 2 is focused at infinity. From these diagrams, it can be seen that the optical system according to Example 2 has excellent correction for various aberrations and has excellent imaging performance.

[0115] (Third Example) Example 3 will be described with reference to Fig. 5, Fig. 6, and Table 3. Fig. 5 is a diagram showing the lens configuration of an optical system according to Example 3. The optical system OL(3) according to Example 3 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0116] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a meniscus positive lens L11 with a convex surface facing the object side, a meniscus positive lens L12 with a convex surface facing the object side, a meniscus positive lens L13 with a convex surface facing the object side, a biconvex positive lens L14, a cemented lens of a biconcave negative lens L15 and a meniscus positive lens L16 with a convex surface facing the object side, a cemented lens of a biconcave negative lens L17 and a biconvex positive lens L18, a meniscus negative lens L19 with a convex surface facing the object side, and a meniscus positive lens L20 with a convex surface facing the object side. When focusing from an object at infinity to a close object, the positive lens L20 moves toward the object side.

[0117] The second lens group G2 is composed of a cemented lens of a meniscus positive lens L21 with its convex surface facing the image side and a biconcave negative lens L22, a meniscus negative lens L23 with its convex surface facing the image side, a biconvex positive lens L24, a cemented lens of a biconvex positive lens L25 and a biconcave negative lens L26, a cemented lens of a biconvex positive lens L27 and a biconcave negative lens L28, and a biconvex positive lens L29.

[0118] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0119] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, the positive lens L14 corresponds to the fourth positive lens, and the negative lens L15 corresponds to the first negative lens L1n. The negative lens L28 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(3). The negative lens L20 constitutes a focusing lens group that moves when focusing from an object at infinity to a close object. The cemented lens of the positive lens L21 and the negative lens L22 in the second lens group G2, together with the negative lens L23, constitutes a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0120] Table 3 below shows the values ​​of the specifications of the optical system according to the third example.

[0121] (Table 3) [Overall specifications] f=497.01 FNO=4.12 2ω=2.45 Y=21.63 TL=410.000 BF=104.010 fp1=468.274 fp12=274.744 fp123=199.280 [Lens specifications] Surface number RD nd νd 1 183.8266 11.274 1.49700 81.61 2 857.0014 118.337 3 111.3036 7.247 1.49700 81.61 4 200.0000 7.739 5 114.3357 7.088 1.43384 95.16 6 237.2358 19.929 7 102.3063 9.370 1.43384 95.16 8 -509.8616 0.100 9 -691.1528 2.793 1.80610 40.97 10 66.2371 8.648 1.66382 27.35 11 381.1106 1.805 12 -618.4030 2.474 1.61266 44.46 13 108.6957 7.294 1.43700 95.10 14 -413.4592 9.294 15 86.3972 1.935 1.92286 20.88 16 53.5424 Variable (D16) 17 60.1559 6.265 1.56732 42.58 18 330.2347 Variable (D18) 19 ∞ 2.500 (Aperture) 20 -1669.6841 4.351 1.94595 17.98 21 -91.5907 1.310 1.87071 40.73 22 63.0357 3.381 23 -88.5940 1.258 2.00100 29.12 24 -7197.8366 2.100 25 163.0699 4.644 1.72047 34.71 26 -117.8305 0.100 27 52.7299 6.300 1.61293 36.94 28 -84.7935 1.300 1.94595 17.98 29 66.4499 19.439 30 128.5739 5.954 2.00069 25.46 31 -77.8412 1.500 1.49782 82.57 32 52.0502 2.360 33 293.4462 3.735 1.74077 27.74 34 -537.9493 BF [Variable Interval Data] Infinity focus Close focus f=497.01 β=0.130 D0 ∞ 3716.9 D16 20.200 6.300 D18 3.970 17.860 [Lens group data] Group starting plane focal length G1 1 207.64 G2 20 -140.62

[0122] 6 shows diagrams of various aberrations when the optical system according to Example 3 is focused at infinity. From these diagrams, it can be seen that the optical system according to Example 3 has excellent correction for various aberrations and has excellent imaging performance.

[0123] (Fourth Example) Example 4 will be described with reference to Fig. 7, Fig. 8, and Table 4. Fig. 7 is a diagram showing the lens configuration of an optical system according to Example 4. The optical system OL(4) according to Example 4 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0124] The first lens group G1 is composed of, arranged along the optical axis from the object side, a biconvex positive lens L11, a meniscus positive lens L12 with its convex surface facing the object side, a cemented lens of a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens of a biconvex positive lens L15 and a biconcave negative lens L16, a meniscus positive lens L17 with its convex surface facing the object side, a cemented lens of a meniscus negative lens L18 with its convex surface facing the object side and a biconvex positive lens L19, a meniscus negative lens L20 with its convex surface facing the object side, and a cemented lens of a meniscus negative lens L21 with its convex surface facing the object side and a meniscus positive lens L22 with its convex surface facing the object side. When focusing from an object at infinity to a close distance, the negative lens L20 moves toward the image plane.

[0125] The second lens group G2 is composed of a cemented lens of a biconvex positive lens L25 and a biconcave negative lens L26, a biconcave negative lens L27, a biconvex positive lens L28, a cemented lens of a meniscus positive lens L29 with its convex surface facing the object side and a meniscus negative lens L30 with its convex surface facing the object side, a cemented lens of a biconvex positive lens L31 and a biconcave negative lens L32, and a cemented lens of a biconvex positive lens L33 and a plano-concave negative lens L34 with its concave surface facing the object side.

[0126] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0127] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, and the negative lens L14 corresponds to the first negative lens L1n. The negative lens L34 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(4). The negative lens L20 constitutes a focusing lens group that moves when focusing from an object at infinity to a close object. The cemented lens of the positive lens L25 and the negative lens L26 in the second lens group G2, together with the negative lens L27, constitutes a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0128] Table 4 below shows the values ​​of the specifications of the optical system according to the fourth example.

[0129] (Table 4) [Overall specifications] f=497.01 FNO=4.12 2ω=2.45 Y=21.63 TL=340,000 BF=67.277 fp1=375.548 fp12=206.285 fp123=114.924 [Lens specifications] Surface number RD nd νd 1 189.8400 13.370 1.48749 70.32 2 -5019.7168 67.953 3 99.7766 10.642 1.43384 95.16 4 255.1599 40.751 5 75.8592 12.107 1.43384 95.16 6 -304.6165 2.528 1.73211 46.18 7 48.2862 2.000 8 46.0436 14.251 1.43700 95.10 9 -239.6197 2.202 1.74950 35.25 10 309.8608 6.822 11 55.4378 7.795 1.80518 25.45 12 274.4646 1.000 13 291.3854 1.872 1.73211 46.18 14 31.1241 11.771 1.43700 95.10 15 -178.9385 Variable (D15) 16 219.5003 2.000 1.60738 56.74 17 41.0948 Variable (D17) 18 89.7622 1.089 1.92286 20.88 19 22.5962 6.998 1.85000 27.03 20 3517.9882 1.522 21 ∞ 1.500 (Aperture) 22 1497.7896 4.097 1.94595 17.98 23 -78.6141 1.020 1.87071 40.73 24 49.5814 2.341 25 -108.9022 1.000 1.87071 40.73 26 81.8950 2.544 27 43.5565 5.041 1.60342 38.03 28 -310.1479 0.100 29 36.0198 4.280 1.78472 25.64 30 76.6504 1.000 1.94595 17.98 31 29.3058 6.887 32 69.5775 7.728 1.68376 37.64 33 -24.1649 1.500 1.78590 44.17 34 40.1248 0.100 35 39.6674 9.331 1.68376 37.64 36 -26.6336 1.500 1.49782 82.57 37∞BF [Variable Interval Data] Infinity focus Close focus f=497.01 β=0.130 D0 ∞ 3665.14 D15 3.000 12.290 D17 13.080 3.790 [Lens group data] Group starting plane focal length G1 1 211.50 G2 22 -86.69

[0130] 8 shows diagrams of various aberrations when the optical system according to Example 4 is focused at infinity. From these diagrams, it can be seen that the optical system according to Example 4 has excellent correction for various aberrations and has excellent imaging performance.

[0131] (Fifth Example) Example 5 will be described with reference to Figs. 9, 10, and Table 5. Fig. 9 is a diagram showing the lens configuration of an optical system according to Example 5. The optical system OL(5) according to Example 5 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0132] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a meniscus positive lens L11 with a convex surface facing the object side, a meniscus positive lens L12 with a convex surface facing the object side, a cemented lens of a biconvex positive lens L13 and a biconcave negative lens L14, a cemented lens of a biconvex positive lens L15 and a biconcave negative lens L16, a meniscus positive lens L17 with a convex surface facing the object side, a cemented lens of a meniscus negative lens L18 with a convex surface facing the object side and a meniscus positive lens L19 with a convex surface facing the object side, a meniscus negative lens L20 with a convex surface facing the object side, and a cemented lens of a meniscus negative lens L21 with a convex surface facing the object side and a biconvex positive lens L22. When focusing from an object at infinity to an object at a close distance, the negative lens L20 moves toward the image plane.

[0133] The second lens group G2 is composed of a cemented lens of a biconvex positive lens L25 and a biconcave negative lens L26, a biconcave negative lens L27, a biconvex positive lens L28, a cemented lens of a meniscus positive lens L29 with its convex surface facing the object side and a meniscus negative lens L30 with its convex surface facing the object side, a cemented lens of a biconvex positive lens L31 and a biconcave negative lens L32, and a cemented lens of a biconvex positive lens L33 and a plano-concave negative lens L34 with its concave surface facing the object side.

[0134] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0135] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, and the negative lens L14 corresponds to the first negative lens L1n. The negative lens L34 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(5). The negative lens L20 constitutes a focusing lens group that moves when focusing from an object at infinity to a close object. The cemented lens of the positive lens L25 and the negative lens L26 in the second lens group G2, together with the negative lens L27, constitutes a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0136] Table 5 below shows the values ​​of the specifications of the optical system according to the fifth example.

[0137] (Table 5) [Overall specifications] f=497.01 FNO=4.12 2ω=2.45 Y=21.63 TL=340,000 BF=67.999 fp1=356.622 fp12=204.808 fp123=117.482 [Lens specifications] Surface number RD nd νd 1 166.2846 13.835 1.49700 81.61 2 2615.8947 77.786 3 92.4857 9.951 1.43384 95.16 4 211.1070 37.083 5 73.6785 11.215 1.43384 95.16 6 -394.3544 2.441 1.73211 46.18 7 46.7356 2.000 8 43.9658 13.355 1.43700 95.10 9 -319.2059 2.125 1.74950 35.25 10 305.1864 2.300 11 50.9793 7.256 1.80518 25.45 12 149.6027 1.000 13 158.3858 1.823 1.73211 46.18 14 29.2214 10.583 1.43700 95.10 15 2223.0426 Variable (D15) 16 408.9541 2.000 1.60738 56.74 17 45.0268 Variable (D17) 18 128.5842 1.105 1.92286 20.88 19 24.6890 7.256 1.85000 27.03 20 -169.2724 1.500 21 ∞ 1.500 (Aperture) 22 8244.5617 4.076 1.94595 17.98 23 -78.6529 1.034 1.87071 40.73 24 50.4898 2.257 25 -127.5306 1.000 1.87071 40.73 26 77.8613 2.609 27 51.6690 4.820 1.60342 38.03 28 -235.9491 0.100 29 39.9696 4.654 1.78472 25.64 30 212.3443 1.000 1.94595 17.98 31 34.1743 7.278 32 73.1779 7.698 1.68376 37.64 33 -24.4808 1.500 1.78590 44.17 34 37.5899 0.102 35 37.6789 9.790 1.68376 37.64 36 -25.4610 1.500 1.49782 82.57 37∞BF [Variable Interval Data] Infinity focus Close focus f=497.01 β=0.130 D0 ∞ 3699.04 D15 3.000 12.890 D17 13.470 3.570 [Lens group data] Group starting plane focal length G1 1 202.60 G2 22 -81.95

[0138] 10 shows diagrams of various aberrations when the optical system according to Example 5 is focused at infinity. From these diagrams, it can be seen that the optical system according to Example 5 has excellent correction for various aberrations and has excellent imaging performance.

[0139] (Sixth Example) Example 6 will be described with reference to FIGS. 11, 12, and Table 6. FIG. 11 is a diagram showing the lens configuration of an optical system according to Example 6. The optical system OL(6) according to Example 6 is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, an aperture stop S, and a second lens group G2 having negative refractive power.

[0140] The first lens group G1 is composed of, arranged in order from the object side along the optical axis, a meniscus positive lens L11 with a convex surface facing the object side, a meniscus positive lens L12 with a convex surface facing the object side, a meniscus positive lens L13 with a convex surface facing the object side, a cemented lens of a biconvex positive lens L14 and a biconcave negative lens L15, a cemented lens of a biconvex positive lens L16 and a biconcave negative lens L17, a meniscus positive lens L18 with a convex surface facing the object side, a cemented lens of a meniscus negative lens L19 with a convex surface facing the object side and a biconvex positive lens L20, a meniscus negative lens L21 with a convex surface facing the object side, and a cemented lens of a meniscus negative lens L22 with a convex surface facing the object side and a biconvex positive lens L23. When focusing from an object at infinity to an object at a close distance, the negative lens L21 moves toward the image plane.

[0141] The second lens group G2 is composed of a cemented lens of a meniscus positive lens L25 with its convex surface facing the image side and a biconcave negative lens L26, a biconcave negative lens L27, a biconvex positive lens L28, a cemented lens of a meniscus positive lens L29 with its convex surface facing the object side and a meniscus negative lens L30 with its convex surface facing the object side, a cemented lens of a biconvex positive lens L31 and a biconcave negative lens L32, and a cemented lens of a biconvex positive lens L33 and a plano-concave negative lens L34 with its concave surface facing the object side.

[0142] An aperture stop S for adjusting the amount of light is disposed between the first lens group G1 and the second lens group G2.

[0143] In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2 constitutes the rear group GB. The positive lens L11 in the first lens group G1 corresponds to the first positive lens L1p, the positive lens L12 corresponds to the second positive lens L2p, the positive lens L13 corresponds to the third positive lens L3p, the positive lens L14 corresponds to the fourth positive lens, and the negative lens L15 corresponds to the first negative lens L1n. The negative lens L34 corresponds to the negative lens Lrn located closest to the image plane among the negative lenses in the optical system OL(6). The negative lens L21 constitutes a focusing lens group that moves when focusing from an object at infinity to a close object. The cemented lens of the positive lens L25 and the negative lens L26 in the second lens group G2, together with the negative lens L27, constitutes a vibration-proof lens group Gvr that can move in a direction perpendicular to the optical axis, and corrects displacement of the imaging position (image blur on the image plane I) due to camera shake or the like.

[0144] Table 6 below shows the values ​​of the specifications of the optical system according to the sixth example.

[0145] (Table 6) [Overall specifications] f=497.02 FNO=4.12 2ω=2.45 Y=21.63 TL=340,000 BF=66.409 fp1=398.289 fp12=250.589 fp123=182.022 [Lens specifications] Surface number RD nd νd 1 171.1133 12.878 1.48749 70.32 2 1405.9110 66.481 3 132.5634 7.626 1.49700 81.61 4 250.0000 1.557 5 135.5484 8.089 1.43384 95.16 6 328.5061 34.000 7 80.4144 11.822 1.43384 95.16 8 -253.3526 2.263 1.73211 46.18 9 47.9043 2.000 10 46.0010 14.134 1.43700 95.10 11 -200.3985 2.370 1.74950 35.25 12 344.9736 2.787 13 55.6006 7.486 1.80518 25.45 14 212.7473 1.000 15 207.0742 1.668 1.73211 46.18 16 31.9494 11.637 1.43700 95.10 17 -174.9344 Variable (D17) 18 358.5187 2.000 1.60738 56.74 19 39.1867 Variable (D19) 20 166.9535 1.086 1.92286 20.88 21 25.8367 6.721 1.85000 27.03 22 -231.4627 1.500 23 ∞ 1.555 (Aperture) 24 -1543.9199 4.042 1.94595 17.98 25 -74.9447 1.000 1.87071 40.73 26 48.0883 2.471 27 -101.2950 1.000 1.87071 40.73 28 110.2016 2.314 29 48.0644 4.862 1.60342 38.03 30 -248.9362 8.402 31 39.7625 3.876 1.78472 25.64 32 63.8298 1.000 1.94595 17.98 33 31.6670 6.707 34 61.5515 7.768 1.68376 37.64 35 -28.1497 1.500 1.78590 44.17 36 47.6753 0.100 37 45.3226 8.745 1.68376 37.64 38 -31.9503 1.500 1.49782 82.57 39∞BF [Variable Interval Data] Infinity focus Close focus f=497.02 β=0.130 D0 ∞ 3687.680 D17 3.000 10.560 D19 14.640 7.080 [Lens group data] Group starting plane focal length G1 1 219.82 G2 24 -114.98

[0146] 12 shows diagrams of various aberrations when the optical system according to Example 6 is focused at infinity. From these diagrams, it can be seen that the optical system according to Example 6 has excellent correction for various aberrations and has excellent imaging performance.

[0147] Next, the table of [Values ​​Corresponding to Conditional Expressions] is shown below. This table shows the values ​​corresponding to each conditional expression for all Examples (Examples 1 to 6). Conditional expression (1A),(1B) 2.50 <TL / d1<15.00 Condition (2) 0.40 <d1 / d2<5.00 Condition (3) 1.00 <d1 / d3<8.00 Condition (4) 2.00 <f / d1<16.00 Condition (5) 0.20 <fp12 / f<1.00 Condition (6) 0.05 <fp123 / f<0.60 Condition (7) 0.50 <fA / BF<6.00 Conditional expression (8) 0.80<(-fB) / BF<2.50 Condition (9) 3.50 <fp1 / BF<10.00 Condition (10) 0.80 <fA / (-fB)<5.00 Condition (11) 0.10 <fA / f<0.80 Conditional expression (12) 0.10<(-fB) / f<0.70 Condition (13) 0.10 <TL / f<1.00 Conditional expression (14) ndL1p<1.60 Conditional expression (15) 60.00<νdL1p Conditional expression (16) 60.00<νdLrn

[0148] [Conditional Expression Corresponding Values] (First to Third Examples) Conditional Expression First Example Second Example Third Example (1A),(1B) 3.727 8.357 3.465 (2) 3.149 0.778 15.292 (3) - - 5.938 (4) 4.518 12.216 4.200 (5) 0.456 0.432 0.553 (6) 0.261 0.233 0.401 (7) 2.346 3.140 1.996 (8) 2.088 1.266 1.352 (9) 4.558 6.701 4.502 (10) 1.124 2.480 1.477 (11) 0.462 0.424 0.418 (12) 0.411 0.171 0.283 (13) 0.825 0.684 0.825 (14) 1.49700 1.48749 1.49700 (15) 81.607 70.318 81.607 (16) 82.570 82.570 82.570 [Conditional Expression Corresponding Values] (Fourth to Sixth Examples) Conditional Expression 4th Example 5th Example 6th Example (1A),(1B) 5.003 4.371 5.114 (2) 1.668 2.098 42.705 (3) - - 1.955 (4) 7.314 6.389 7.476 (5) 0.415 0.412 0.504 (6) 0.231 0.236 0.366 (7) 3.144 2.979 3.310 (8) 1.289 1.205 1.731 (9) 5.582 5.245 5.998 (10) 2.440 2.472 1.912 (11) 0.426 0.408 0.442 (12) 0.174 0.165 0.231 (13) 0.684 0.684 0.684 (14) 1.48749 1.49700 1.48749 (15) 70.318 81.607 70.318 (16) 82.570 82.570 82.570

[0149] As described above, according to each embodiment, it is possible to realize an optical system and optical equipment that is lightweight and small, yet has good optical performance.

[0150] In the above-described embodiment, the following contents can be appropriately adopted within the scope that does not impair the optical performance.

[0151] Although a two-group configuration has been shown as an example of the optical system of this embodiment, the present application is not limited to this, and optical systems with other group configurations (for example, three groups, four groups, etc.) can also be configured. Specifically, a configuration in which a lens or lens group is added to the most object side or the most image side of the optical system of this embodiment can also be used. A configuration in which a second focusing lens group is added in addition to one focusing lens group can also be used. Note that a lens group refers to a portion having at least one lens separated by an air gap that changes during focusing.

[0152] The lens surface may be spherical, flat, or aspherical. Spherical or flat lens surfaces are preferred because they facilitate lens processing and assembly adjustment, and prevent degradation of optical performance due to errors in processing and assembly adjustment. Furthermore, they are preferred because they minimize degradation of imaging performance even when the image plane is misaligned.

[0153] If the lens surface is aspherical, the aspherical surface may be any of the following: a ground aspherical surface, a glass-molded aspherical surface in which glass is molded into an aspherical shape, or a hybrid aspherical surface in which a resin is formed into an aspherical shape on the surface of glass. The lens surface may also be a diffractive surface, or the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0154] The aperture diaphragm may not be provided as a component, and the lens frame may play the role of the aperture diaphragm.

[0155] Each lens surface may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range in order to reduce flare and ghosting and achieve high-contrast optical performance. [Explanation of symbols]

[0156] OL optical system G1 First lens group G2 Second lens group GA front group GB rear group L1p 1st positive lens L2p 2nd positive lens L3p 3rd positive lens L4p 4th positive lens L1n First negative lens Gvr vibration-proof lens group S Aperture stop I Image plane

Claims

1. It consists of a front group, a stop, and a rear group, arranged in order from the object side along the optical axis. the front group includes, in order from the object side, a first positive lens, a second positive lens, a third positive lens, and a first negative lens; the first positive lens and the second positive lens are each composed of a single lens, An optical system that satisfies the following condition: 2.50<TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

2. It consists of a front group, a stop, and a rear group, arranged in order from the object side along the optical axis. the front group includes, in order from the object side, a first positive lens, a second positive lens, a third positive lens, a fourth positive lens, and a first negative lens; the first positive lens, the second positive lens, and the third positive lens are each composed of a single lens, An optical system that satisfies the following condition: 2.50<TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

3. 2. The optical system according to claim 1, wherein the following condition is satisfied: 0.40<d1 / d2<5.00 where d2 is the distance on the optical axis from the lens surface of the second positive lens on the image side to the lens surface of the third positive lens on the object side.

4. 3. The optical system according to claim 2, wherein the following condition is satisfied: 1.00<d1 / d3<8.00 where d3 is the distance on the optical axis from the lens surface of the third positive lens on the image plane side to the lens surface of the fourth positive lens on the object side.

5. 5. The optical system according to claim 1, wherein the following condition is satisfied: 2.00<f / d1<16.00 where f is the focal length of the entire optical system.

6. 6. The optical system according to claim 1, wherein the following condition is satisfied: 0.20<fp12 / f<1.00 where fp12 is the composite focal length of the first positive lens and the second positive lens. f: focal length of the entire optical system

7. 7. The optical system according to claim 1, wherein the following condition is satisfied: 0.05<fp123 / f<0.60 where fp123 is the composite focal length of the first positive lens, the second positive lens, and the third positive lens. f: focal length of the entire optical system

8. 8. The optical system according to claim 1, wherein the following condition is satisfied: 0.50<fA / BF<6.00 where fA is the focal length of the front group BF: the distance on the optical axis from the lens surface closest to the image plane in the optical system to the image plane

9. 9. The optical system according to claim 1, wherein the following condition is satisfied: 0.80<(-fB) / BF<2.50 where fB is the focal length of the rear group BF: the distance on the optical axis from the lens surface closest to the image plane in the optical system to the image plane

10. 10. The optical system according to claim 1, wherein the following condition is satisfied: 3.50<fp1 / BF<10.00 where fp1 is the focal length of the first positive lens. BF: the distance on the optical axis from the lens surface closest to the image plane in the optical system to the image plane

11. The optical system according to any one of claims 1 to 10, which satisfies the following conditional expression: 0.80<fA / (-fB)<5.00 where fA is the focal length of the front group fB: focal length of the rear group

12. 12. The optical system according to claim 1, wherein the following condition is satisfied: 0.10<fA / f<0.80 where fA is the focal length of the front group f: focal length of the entire optical system

13. The optical system according to any one of claims 1 to 12, which satisfies the following conditional expression: 0.10<(-fB) / f<0.70 where fB is the focal length of the rear group f: focal length of the entire optical system

14. The optical system according to any one of claims 1 to 13, which satisfies the following conditional expression: 0.10<TL / f<1.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. f: focal length of the entire optical system

15. The optical system according to any one of claims 1 to 14, which satisfies the following conditional expression: ndL1p<1.60 60.00<νdL1p where ndL1p is the refractive index of the first positive lens with respect to the d-line. νdL1p: Abbe number of the first positive lens based on the d line

16. The optical system according to any one of claims 1 to 15, which satisfies the following conditional expression: 60.00<νdLrn where νdLrn is the Abbe number based on the d-line of the negative lens arranged closest to the image plane among the negative lenses in the optical system.

17. 17. The optical system according to claim 1, wherein the rear group includes at least two cemented lenses.

18. The optical system according to any one of claims 1 to 17, wherein an image stabilization lens group is disposed adjacent to the diaphragm, the image stabilization lens group moving in a direction perpendicular to the optical axis to correct an image formed on an image plane.

19. the front group includes a focusing lens group that moves during focusing, The optical system according to any one of claims 1 to 18, wherein the focusing lens group is composed of one lens component.

20. 20. The optical system according to claim 1, wherein the rear group has negative refractive power.

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

22. A front group, a stop, and a rear group are arranged in this order from the object side along the optical axis within the lens barrel, the front group includes, in order from the object side, a first positive lens, a second positive lens, a third positive lens, and a first negative lens; A method for manufacturing an optical system in which the first positive lens and the second positive lens are both single lenses and are configured to satisfy the following conditional expression: 2.50<TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

23. A front group, a stop, and a rear group are arranged in this order from the object side along the optical axis within the lens barrel, the front group includes, in order from the object side, a first positive lens, a second positive lens, a third positive lens, a fourth positive lens, and a first negative lens; A method for manufacturing an optical system in which the first positive lens, the second positive lens, and the third positive lens are all single lenses and are configured to satisfy the following conditional expressions: 2.50<TL / d1<15.00 where TL is the distance on the optical axis from the lens surface closest to the object side of the optical system to the image plane. d1: the distance on the optical axis from the lens surface of the first positive lens on the image plane side to the lens surface of the second positive lens on the object side

Images