Optical system and optical apparatus

Abstract

The optical system (OL) consists of a front group (GA), an aperture (S), and a rear group (GB) arranged sequentially along the optical axis from the object side. The rear group (GB) has a first focusing lens group (GF1) and a second focusing lens group (GF2). The first focusing lens group (GF1) is located on the object side of the rear group (GB) and has negative optical power. The second focusing lens group (GF2) is located on the image plane side compared to the first focusing lens group (GF1) and also has negative optical power. When focusing from an object at infinity to a closer object, the first focusing lens group (GF1) and the second focusing lens group (GF2) move along the optical axis to the image plane side along different trajectories.

Description

Technical Field

[0001] This invention relates to optical systems, optical devices, and methods for manufacturing optical systems. Background Technology

[0002] Previously, optical systems that move multiple lens groups along the optical axis for focusing have been disclosed (for example, see Patent Document 1). In such optical systems, the focusing lens group becomes heavy, making it difficult to suppress aberrations during focusing.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-155228 Summary of the Invention

[0006] The optical system of the first invention comprises a front group, an aperture, and a rear group arranged sequentially along the optical axis from the object side. The rear group has a first focusing lens group and a second focusing lens group. The first focusing lens group is located closest to the object side of the rear group and has negative optical power. The second focusing lens group is located on the image plane side compared to the first focusing lens group and also has negative optical power. When focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move along the optical axis to the image plane side along different trajectories.

[0007] The second optical system of the present invention comprises a front lens group with positive optical power, a first focusing lens group with negative optical power, a positive lens group with positive optical power, a second focusing lens group with negative optical power, and a final lens group arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move along the optical axis to the image plane side along different trajectories.

[0008] The optical device of the present invention is configured to include the above-described optical system.

[0009] Regarding the manufacturing method of the optical system of the first invention, the optical system comprises a front group, an aperture, and a rear group arranged sequentially along the optical axis from the object side, wherein each lens is arranged in the lens barrel in the following manner: the rear group has a first focusing lens group and a second focusing lens group, the first focusing lens group being disposed on the object side of the rear group and having negative optical power, and the second focusing lens group being disposed on the image plane side compared to the first focusing lens group and having negative optical power; when focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move along the optical axis on the image plane side along different trajectories.

[0010] Regarding the manufacturing method of the optical system of the second invention, the optical system comprises a front lens group with positive optical power, a first focusing lens group with negative optical power, a positive lens group with positive optical power, a second focusing lens group with negative optical power, and a final lens group arranged sequentially along the optical axis from the object side, wherein each lens is arranged in the lens barrel in such a way that when focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move along the optical axis to the image plane side along different trajectories. Attached Figure Description

[0011] Figure 1 This is a diagram showing the lens structure of the optical system of the first embodiment.

[0012] Figure 2 (A) Figure 2 (B) are aberration diagrams of the optical system of the first embodiment when focusing at infinity and when focusing at close range.

[0013] Figure 3 This is a diagram showing the lens structure of the optical system of the second embodiment.

[0014] Figure 4 (A) Figure 4 (B) are aberration diagrams of the optical system of the second embodiment when focusing at infinity and when focusing at close range.

[0015] Figure 5 This is a diagram showing the lens structure of the optical system of the third embodiment.

[0016] Figure 6 (A) Figure 6 (B) are aberration diagrams of the optical system of the third embodiment when focusing at infinity and when focusing at close range.

[0017] Figure 7 This is a diagram showing the lens structure of the optical system of the fourth embodiment.

[0018] Figure 8 (A) Figure 8 (B) are aberration diagrams of the optical system of the fourth embodiment when focusing at infinity and when focusing at close range.

[0019] Figure 9 This is a diagram showing the lens structure of the optical system of the fifth embodiment.

[0020] Figure 10 (A) Figure 10 (B) are aberration diagrams of the optical system of the fifth embodiment when focusing at infinity and when focusing at close range.

[0021] Figure 11 This is a diagram showing the lens structure of the optical system of the sixth embodiment.

[0022] Figure 12 (A) Figure 12 (B) are aberration diagrams of the optical system of the sixth embodiment when focusing at infinity and when focusing at close range.

[0023] Figure 13 This is a diagram showing the lens structure of the optical system of the seventh embodiment.

[0024] Figure 14 (A) Figure 14 (B) are aberration diagrams of the optical system of the 7th embodiment when focusing at infinity and when focusing at close range.

[0025] Figure 15 This is a diagram showing the lens structure of the optical system of the eighth embodiment.

[0026] Figure 16 (A) Figure 16 (B) are aberration diagrams of the optical system of the 8th embodiment when focusing at infinity and when focusing at close range.

[0027] Figure 17 This is a diagram showing the lens structure of the optical system of the 9th embodiment.

[0028] Figure 18 (A) Figure 18 (B) are aberration diagrams of the optical system of the 9th embodiment when focusing at infinity and when focusing at close range.

[0029] Figure 19 This is a diagram showing the lens structure of the optical system of the 10th embodiment.

[0030] Figure 20 (A) Figure 20 (B) are aberration diagrams of the optical system of the 10th embodiment at infinity and at close range, respectively, in the wide-angle end state.

[0031] Figure 21 (A) Figure 21 (B) are aberration diagrams of the optical system of the 10th embodiment at infinity and at close range, respectively.

[0032] Figure 22 This is a diagram showing the structure of a camera equipped with an optical system according to various embodiments.

[0033] Figure 23This is a flowchart illustrating a method for manufacturing an optical system according to the first embodiment.

[0034] Figure 24 This is a flowchart illustrating a method for manufacturing an optical system according to the second embodiment. Detailed Implementation

[0035] The preferred embodiments of the present invention will be described below. First, according to... Figure 22 A camera (optical device) having an optical system with each embodiment will be described. For example... Figure 22 As shown, the camera 1 consists of a main body 2 and a camera lens 3 mounted on the main body 2. The main body 2 includes an image sensor 4, a main control unit (not shown) for controlling the operation of the digital camera, and an LCD screen 5. The camera lens 3 includes an optical system OL consisting of multiple lens groups and a lens position control mechanism (not shown) for controlling the position of each lens group. The lens position control mechanism consists of a sensor for detecting the position of the lens groups, a motor for moving the lens groups back and forth along the optical axis, and a control circuit for driving the motor.

[0036] Light from the subject is focused by the optical system OL of the camera lens 3 and reaches the image plane I of the image sensor 4. The light from the subject reaching the image plane I is then 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 according to user operation. Furthermore, this camera can be a mirrorless camera or a single-lens reflex camera with a reflex mirror. Figure 22 The optical system OL shown schematically illustrates an optical system included in the photographic lens 3, but the lens structure of the optical system OL is not limited to this structure.

[0037] Next, the optical system of the first embodiment will be described. For example... Figure 1 As shown, the optical system OL (1), as an example of the optical system OL in the first embodiment, consists of a front group GA, an aperture (aperture stop) S, and a rear group GB arranged sequentially along the optical axis from the object side. The rear group GB has a first focusing lens group GF1 and a second focusing lens group GF2. The first focusing lens group GF1 is located closest to the object side of the rear group GB and has negative optical power. The second focusing lens group GF2 is located on the image plane side compared to the first focusing lens group GF1 and also has negative optical power. When focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move along the optical axis to the image plane side along different trajectories.

[0038] According to the first embodiment, an optical system with minimal aberration during focusing and an optical device equipped with such an optical system can be obtained. Furthermore, since the aberration during focusing is minimal, large aperture and excellent optical performance can be achieved. Because each focusing lens group can be made lightweight, an optical system compatible with high-speed autofocus (AF) can be obtained. Because the drive mechanism for each focusing lens group can be simplified, the sensitivity of optical performance to manufacturing errors can be suppressed.

[0039] The optical system OL in the first embodiment can be Figure 3 The zoom 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 Figure 9 The optical system OL(5) shown. Alternatively, the optical system OL of the first embodiment may also be... Figure 11 The zoom optical system OL(6) shown can also be Figure 13 The optical system OL(7) shown can also be Figure 19 The optical system shown

[0040] OL(10).

[0041] The optical system OL of the first embodiment preferably satisfies the following conditional expression (1).

[0042] 0.30 <STL / TL<0.90…(1)

[0043] Where STL: the distance on the optical axis from aperture S to image plane I.

[0044] TL: Total length of the optical system OL

[0045] Condition (1) specifies an appropriate relationship between the distance on the optical axis from the aperture S to the image plane I and the total length of the optical system OL. By satisfying condition (1), the pupil position can be deduced, and a suitable range of aperture positions can be specified. In addition, field of view variations corresponding to changes in back focal length caused by manufacturing errors can be suppressed. Furthermore, in each embodiment, the total length of the optical system OL is the distance (air equivalent distance) on the optical axis from the lens surface of the optical system OL closest to the object when focusing at infinity to the image plane I.

[0046] When the corresponding value of conditional expression (1) is lower than the lower limit, the exit pupil approaches the image plane I, and therefore the angle of inclination of the light rays incident on the image plane I becomes steeper. This makes it easier for the field of view to change due to variations in the back focal length caused by manufacturing errors, etc. By setting the lower limit of conditional expression (1) to 0.33, 0.35, 0.38, 0.40, 0.43, 0.45, 0.48, 0.50, and further setting it to 0.52, the effects of this embodiment can be obtained more reliably.

[0047] When the corresponding value of conditional expression (1) is higher than the upper limit value, the cutting ratio of the upper and lower rays in aperture S becomes uneven due to the unsuitable position of aperture S, resulting in a so-called single aperture. Furthermore, aberration correction is difficult to perform because the total length of the optical system OL is too short. By setting the upper limit value of conditional expression (1) to 0.88, 0.85, 0.83, 0.80, 0.78, and further setting it to 0.76, the effects of this embodiment can be obtained more reliably.

[0048] In the optical system OL of the first embodiment, it is preferable that the rear group GB has a positive lens group GP, which is disposed between the first focusing lens group GF1 and the second focusing lens group GF2, and has positive optical power. When focusing from an object at infinity to a closer object, the position of the positive lens group GP relative to the image plane I is fixed. As a result, spherical aberration, Petzval, etc., can be well corrected.

[0049] In the optical system OL of the first embodiment, it is preferable that the front group GA is composed of a front lens group GA1 having positive optical power, and the rear group GB has a positive lens group GP and a final lens group GE. The positive lens group GP is disposed between the first focusing lens group GF1 and the second focusing lens group GF2 and has positive optical power. The final lens group GE is disposed on the image plane side relative to the second focusing lens group GF2. Therefore, by distributing multiple focusing lens groups on the image plane side relative to the aperture S, it is easy to align the axes of the multiple focusing lens groups together during focusing, thus suppressing the sensitivity of optical performance to manufacturing errors. Furthermore, by moving the multiple focusing lens groups during focusing, the focusing lens groups can be made lighter, and aberration variations during focusing can be effectively suppressed.

[0050] Next, the optical system of the second embodiment will be described. For example... Figure 1As shown, the optical system OL (1), as an example of the optical system OL in the second embodiment, is configured to include a front lens group GA1 with positive optical power, a first focusing lens group GF1 with negative optical power, a positive lens group GP with positive optical power, a second focusing lens group GF2 with negative optical power, and a final lens group GE, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move along the optical axis towards the image plane along different trajectories.

[0051] According to the second embodiment, an optical system with minimal aberration during focusing and an optical device equipped with such an optical system can be obtained. Furthermore, since the aberration during focusing is minimal, large aperture and excellent optical performance can be achieved. Because each focusing lens group can be made lightweight, an optical system compatible with high-speed autofocus (AF) can be obtained. Because the drive mechanism for each focusing lens group can be simplified, the sensitivity of optical performance to manufacturing errors can be suppressed.

[0052] The optical system OL in the second embodiment can be Figure 3 The zoom 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 Figure 9 The optical system OL(5) shown is an example. Alternatively, the optical system OL of the second embodiment could also be... Figure 11 The zoom optical system OL(6) shown can also be Figure 13 The optical system OL(7) shown can also be Figure 15 The optical system shown

[0053] OL(8) can also be Figure 17 The optical system OL(9) shown can also be Figure 19 The optical system OL(10) shown is illustrated.

[0054] In the optical system OL of the second embodiment, it is preferable to arrange an aperture stop (aperture stop) S between the front lens group GA1 and the first focusing lens group GF1. This effectively concentrates the light incident on the focusing lens group, enabling the focusing lens group to be compact and lightweight. Furthermore, it facilitates the alignment of the multiple focusing lens groups during focusing, suppressing the sensitivity of optical performance to manufacturing errors. Additionally, it allows for good correction of field-of-view variations during focusing.

[0055] The optical system OL of the second embodiment preferably satisfies the conditional expression (1) described above. By satisfying conditional expression (1), the pupil position can be deduced analogously, just as in the first embodiment, and a suitable range of aperture position can be defined. In addition, field of view variation caused by back focal length changes due to manufacturing errors can be suppressed. By setting the lower limit of conditional expression (1) to 0.33, 0.35, 0.38, 0.40, 0.43, 0.45, 0.48, 0.50, and further to 0.52, the effects of this embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (1) to 0.88, 0.85, 0.83, 0.80, 0.78, and further to 0.76, the effects of this embodiment can be obtained more reliably.

[0056] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (2).

[0057] 0.50 <fA / f<2.00…(2)

[0058] Where fA: focal length of the front lens group GA1

[0059] f: Focal length of the optical system OL

[0060] Condition (2) specifies the appropriate relationship between the focal length of the front lens group GA1 and the focal length of the optical system OL. By satisfying condition (2), chromatic aberration can be well corrected, and the overall length of the optical system OL can be shortened.

[0061] When the corresponding value of conditional expression (2) deviates from the above range, it is difficult to correct the color difference and to shorten the overall length of the optical system OL. By setting the lower limit of conditional expression (2) to 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, and further to 0.95, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (2) to 1.90, 1.80, 1.75, 1.70, 1.65, 1.60, 1.55, 1.50, and further to 1.45, the effects of each embodiment can be obtained more reliably.

[0062] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (3).

[0063] 0.50 <fA / (-fF1)<1.50…(3)

[0064] Where fA: focal length of the front lens group GA1

[0065] fF1: Focal length of the first focusing lens group GF1

[0066] Condition (3) specifies the appropriate relationship between the focal length of the front lens group GA1 and the focal length of the first focusing lens group GF1. By satisfying condition (3), aberration variation and field of view variation during focusing can be reduced.

[0067] When the corresponding value of condition (3) deviates from the above range, it is difficult to suppress aberration changes and field of view changes during focusing. By setting the lower limit of condition (3) to 0.53, 0.55, 0.58, 0.60, 0.63, 0.65, 0.58, 0.70, and further to 0.73, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (3) to 1.48, 1.45, 1.43, 1.40, 1.38, 1.35, and further to 1.33, the effects of each embodiment can be obtained more reliably.

[0068] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (4).

[0069] 0.35 <fB / (-fF1)<1.50…(4)

[0070] Wherein, fB: the combined focal length of the lens group GF1 positioned on the image plane side compared to the first focusing lens group.

[0071] fF1: Focal length of the first focusing lens group GF1

[0072] Condition (4) specifies an appropriate relationship between the combined focal length of the lens group GF1 positioned on the image plane side and the focal length of the first focusing lens group GF1. By satisfying condition (4), aberration variations and field of view variations during focusing can be reduced.

[0073] When the corresponding value of condition (4) deviates from the above range, it is difficult to suppress aberration changes and field of view changes during focusing. By setting the lower limit of condition (4) to 0.38, 0.40, 0.43, 0.45, 0.48, 0.50, 0.53, 0.55, 0.58, and further to 0.60, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (4) to 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.18, 1.20, 1.15, 1.13, and further to 1.10, the effects of each embodiment can be obtained more reliably.

[0074] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (5).

[0075] -2.00<(-fE) / f<15.00…(5)

[0076] Where fE: the focal length of the final lens group GE

[0077] f: Focal length of the optical system OL

[0078] Condition (5) specifies the appropriate relationship between the focal length of the final lens group GE and the focal length of the optical system OL. By satisfying condition (5), shading can be suppressed and the overall length of the optical system OL can be shortened.

[0079] When the corresponding value of condition (5) deviates from the above range, it is difficult to suppress shadows and difficult to shorten the overall length of the optical system OL. By setting the lower limit of condition (5) to -1.80, -1.50, -1.00, -0.50, -0.10, 0.10, 0.50, 0.65, 0.80, and further to 0.90, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (5) to 14.80, 12.00, 10.00, 8.50, 7.50, 6.00, 5.00, 4.50, and further to 4.00, the effects of each embodiment can be obtained more reliably.

[0080] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (6).

[0081] -1.00 <fP / (-fE)<1.50…(6)

[0082] Where fP: focal length of the positive lens group GP

[0083] fE: Focal length of the final lens group GE

[0084] Condition (6) specifies the appropriate relationship between the focal length of the positive lens group GP and the focal length of the final lens group GE. By satisfying condition (6), aberrations during focusing can be effectively suppressed, and the exit pupil can be moved away from the image plane I.

[0085] When the corresponding value of conditional expression (6) deviates from the above range, it is difficult to suppress aberration changes during focusing. By setting the lower limit of conditional expression (6) to -0.80, -0.50, -0.25, -0.10, 0.01, 0.05, 0.12, and further to 0.15, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (6) to 1.40, 1.25, 1.00, 0.85, 0.70, 0.65, 0.60, and further to 0.55, the effects of each embodiment can be obtained more reliably.

[0086] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (7).

[0087] 1.10<(-fF1) / fP<3.20…(7)

[0088] Where fF1: the focal length of the first focusing lens group GF1

[0089] fP: Focal length of the positive lens group GP

[0090] Condition (7) specifies the appropriate relationship between the focal length of the first focusing lens group GF1 and the focal length of the positive lens group GP. By satisfying condition (7), the generation of spherical aberration and axial chromatic aberration can be effectively suppressed.

[0091] When the corresponding value of condition (7) deviates from the above range, it is difficult to correct spherical aberration and axial chromatic aberration. By setting the lower limit of condition (7) to 1.15, 1.20, 1.25, 1.30, 1.33, 1.35, 1.38, 1.40, 1.43, and further to 1.45, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (7) to 3.15, 3.10, 3.05, and further to 3.00, the effects of each embodiment can be obtained more reliably.

[0092] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (8).

[0093] 0.30 <fP / f<1.00…(8)

[0094] Where fP: focal length of the positive lens group GP

[0095] f: Focal length of the optical system OL

[0096] Condition (8) specifies the appropriate relationship between the focal length of the positive lens group GP and the focal length of the optical system OL. By satisfying condition (8), spherical aberration, Petzval, and other aberrations can be well corrected.

[0097] When the corresponding value of condition (8) deviates from the above range, it is difficult to correct spherical aberration, Petzval, etc. By setting the lower limit of condition (8) to 0.33, 0.35, 0.38, 0.40, and further to 0.43, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (8) to 0.98, 0.95, 0.93, 0.90, and further to 0.88, the effects of each embodiment can be obtained more reliably.

[0098] In the optical system OL of the first and second embodiments, it is preferable that the positive lens group GP has a negative lens, a first positive lens, and a second positive lens arranged sequentially along the optical axis from the object side. This allows for miniaturization of the optical system OL and enables the exit pupil to move away from the image plane I. Furthermore, it allows for effective correction of various aberrations, primarily spherical aberration.

[0099] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (9).

[0100] 0.10 <fF1 / fF2<2.00…(9)

[0101] Where fF1: the focal length of the first focusing lens group GF1

[0102] fF2: Focal length of the second focusing lens group GF2

[0103] Condition (9) specifies the appropriate relationship between the focal length of the first focusing lens group GF1 and the focal length of the second focusing lens group GF2. By satisfying condition (9), spherical aberration, image plane curvature, etc., can be well corrected.

[0104] When the corresponding value of condition (9) deviates from the above range, it is difficult to correct spherical aberration, image plane curvature, etc. By setting the lower limit of condition (9) to 0.13, 0.15, 0.18, 0.20, 0.23, and further to 0.25, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (9) to 1.98, 1.95, 1.93, 1.90, 1.75, 1.50, 1.40, 1.25, 1.10, and further to 1.00, the effects of each embodiment can be obtained more reliably.

[0105] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (10).

[0106] 0.50 <f / (-fF1)<1.80…(10)

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

[0108] fF1: Focal length of the first focusing lens group GF1

[0109] Condition (10) specifies the appropriate relationship between the focal length of the optical system OL and the focal length of the first focusing lens group GF1. By satisfying condition (10), chromatic aberration, image plane curvature, etc., can be well corrected.

[0110] When the corresponding value of conditional expression (10) deviates from the above range, it is difficult to correct for chromatic aberration, image plane curvature, etc. By setting the lower limit of conditional expression (10) to 0.53, 0.55, 0.58, 0.60, 0.63, 0.65, 0.68, 0.70, 0.73, and further to 0.75, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (10) to 1.78, 1.75, 1.73, 1.70, 1.50, 1.40, and further to 1.20, the effects of each embodiment can be obtained more reliably.

[0111] In the optical system OL of the first and second embodiments, it is preferable that the first focusing lens group GF1 is composed of a negative lens component. This makes the first focusing lens group GF1 lighter, thus enabling high-speed focusing from an object at infinity to a closer object. Furthermore, in each embodiment, the lens component refers to a single lens or a combined lens.

[0112] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (11).

[0113] -2.50<(rF12+rF11) / (rF12-rF11)<0.00…(11)

[0114] Where rF11: the radius of curvature of the lens surface closest to the object in the first focusing lens group GF1.

[0115] rF12: Radius of curvature of the lens surface closest to the image plane of the first focusing lens group GF1.

[0116] Condition (11) specifies an appropriate range for the shape factor of the lens constituting the first focusing lens group GF1. By satisfying condition (11), spherical aberration, coma, etc., can be well corrected.

[0117] When the corresponding value of conditional expression (11) deviates from the above range, it is difficult to correct spherical aberration, coma, etc. By setting the lower limit of conditional expression (11) to -2.45, -2.40, -2.35, -2.30, -2.28, -2.25, and further to -2.23, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (11) to -0.05, -0.10, -0.15, -0.20, -0.25, -0.30, -0.35, -0.40, -0.45, -0.50, and further to -0.55, the effects of each embodiment can be obtained more reliably.

[0118] In the optical system OL of the first and second embodiments, it is preferable that the second focusing lens group GF2 is composed of a negative lens component. This makes the second focusing lens group GF2 lighter, thus enabling high-speed focusing from objects at infinity to objects at close range.

[0119] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (12).

[0120] 0.05 <Bf / TL<0.80…(12)

[0121] Where Bf: the back focal length of the optical system OL

[0122] TL: Total length of the optical system OL

[0123] Condition (12) specifies the appropriate relationship between the back focal length of the optical system OL and the total length of the optical system OL. By satisfying condition (12), spherical aberration, coma, etc., can be well corrected. In addition, in each embodiment, the distance (air equivalent distance) on the optical axis of the optical system OL from the lens surface closest to the image plane to the image plane I when the back focal length of the optical system OL is set to infinity is defined.

[0124] When the corresponding value of conditional expression (12) is lower than the lower limit, a halo is generated on image plane I because the exit pupil is too close to image plane I. When it is desired to avoid this halo, it may be difficult to correct off-axis aberrations, especially coma, which is not preferred. By setting the lower limit of conditional expression (12) to 0.06, and further to 0.07, the effects of each embodiment can be obtained more reliably.

[0125] When the corresponding value of conditional expression (12) is higher than the upper limit, the total length of the optical system OL is too short, making it difficult to correct spherical aberration, coma, etc. In addition, the optical system OL becomes too large due to its excessively long back focal length. By setting the upper limit of conditional expression (12) to 0.75, 0.70, 0.65, 0.50, 0.40, 0.35, 0.30, and further to 0.25, the effects of each implementation method can be obtained more reliably.

[0126] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (13).

[0127] -0.80<(rR2+rR1) / (rR2-rR1)<2.50…(13)

[0128] Where rR1: the radius of curvature of the object-side lens surface of the lens closest to the image plane in the optical system OL.

[0129] rR2: The radius of curvature of the image-side lens surface of the lens closest to the image plane in the optical system OL.

[0130] Condition (13) specifies an appropriate range for the shape factor of the lens positioned on the image plane side of the optical system OL. By satisfying condition (13), coma and other aberrations can be well corrected, and ghosting can be suppressed.

[0131] When the corresponding value of conditional expression (13) deviates from the above range, it is difficult to correct coma and other issues, and it is also difficult to suppress ghosting. By setting the lower limit of conditional expression (13) to -0.75, -0.70, -0.65, -0.60, -0.50, -0.30, 0.30, 0.50, 0.80, and further to 0.95, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (13) to 2.45, 2.35, 2.15, 2.00, 1.85, and further to 1.70, the effects of each embodiment can be obtained more reliably.

[0132] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (14).

[0133] 0.01 < 1 / βF1 < 0.60…(14)

[0134] Wherein, βF1: the lateral magnification of the first focusing lens group GF1 when focusing on an object at infinity.

[0135] Condition (14) specifies an appropriate range for the lateral magnification of the first focusing lens group GF1 when focusing on an object at infinity. By satisfying condition (14), various aberrations such as spherical aberration and image plane curvature when focusing on an object at infinity can be well corrected.

[0136] When the corresponding value of conditional expression (14) deviates from the above range, it becomes difficult to correct various aberrations such as spherical aberration and image plane curvature when focusing on objects at infinity. By setting the lower limit of conditional expression (14) to 0.02, 0.05, and further to 0.08, the effects of each implementation method can be obtained more reliably. In addition, by setting the upper limit of conditional expression (14) to 0.58, 0.55, 0.53, 0.50, 0.48, 0.45, and further to 0.43, the effects of each implementation method can be obtained more reliably.

[0137] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (15).

[0138] 0.50 < 1 / βF2 < 0.95…(15)

[0139] Wherein, βF2: the lateral magnification of the second focusing lens group GF2 when focusing on an object at infinity.

[0140] Condition (15) specifies an appropriate range for the lateral magnification of the second focusing lens group GF2 when focusing on an object at infinity. By satisfying condition (15), various aberrations such as spherical aberration and image plane curvature when focusing on an object at infinity can be well corrected.

[0141] When the corresponding value of conditional expression (15) deviates from the above range, it becomes difficult to correct various aberrations such as spherical aberration and image plane curvature when focusing on objects at infinity. By setting the lower limit of conditional expression (15) to 0.53, 0.55, 0.58, and further to 0.60, the effects of each implementation method can be obtained more reliably. In addition, by setting the upper limit of conditional expression (15) to 0.94, 0.92, 0.90, and further to 0.85, the effects of each implementation method can be obtained more reliably.

[0142] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (16).

[0143] {βF1+(1 / βF1)} -2 <0.20…(16)

[0144] Wherein, βF1: the lateral magnification of the first focusing lens group GF1 when focusing on an object at infinity.

[0145] Condition (16) specifies an appropriate range for the lateral magnification of the first focusing lens group GF1 when focusing on an object at infinity. By satisfying condition (16), various aberrations such as spherical aberration and image plane curvature when focusing on an object at infinity can be well corrected.

[0146] When the corresponding value of condition (16) deviates from the above range, it is difficult to correct various aberrations such as spherical aberration and image plane curvature when focusing on objects at infinity. By setting the upper limit of condition (16) to 0.18, 0.16, 0.15, and further setting it to 0.14, the effects of each implementation method can be obtained more reliably.

[0147] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (17).

[0148] {βF2+(1 / βF2)} -2 ≤0.25…(17)

[0149] Wherein, βF2: the lateral magnification of the second focusing lens group GF2 when focusing on an object at infinity.

[0150] Condition (17) specifies an appropriate range for the lateral magnification of the second focusing lens group GF2 when focusing on an object at infinity. By satisfying condition (17), various aberrations such as spherical aberration and image plane curvature when focusing on an object at infinity can be well corrected. When the corresponding value of condition (17) deviates from the above range, it is difficult to correct various aberrations such as spherical aberration and image plane curvature when focusing on an object at infinity.

[0151] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (18).

[0152] 0.15 <MF2 / MF1<0.80…(18)

[0153] Wherein, MF1: the absolute value of the movement of the first focusing lens group GF1 when focusing from an object at infinity to a closer object.

[0154] MF2: The absolute value of the movement of the second focusing lens group GF2 when focusing from an object at infinity to a closer object.

[0155] Condition (18) specifies the appropriate relationship between the movement of the first focusing lens group GF1 and the movement of the second focusing lens group GF2 when focusing from an object at infinity to a closer object. By satisfying condition (18), spherical aberration, coma, and image plane curvature can be well corrected.

[0156] When the corresponding value of conditional expression (18) deviates from the above range, it becomes difficult to correct spherical aberration, coma, and image plane curvature. By setting the lower limit of conditional expression (18) to 0.16, 0.18, 0.20, and further to 0.22, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of conditional expression (18) to 0.78, 0.75, 0.73, 0.70, and further to 0.68, the effects of each embodiment can be obtained more reliably.

[0157] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (19).

[0158] 20.00°<2ω<40.00°…(19)

[0159] Where 2ω: the full field of view of the optical system OL

[0160] Condition (19) specifies an appropriate range for the full field of view of the optical system OL. By satisfying condition (19), an optical system with a wide field of view can be obtained, which is therefore preferred. By setting the lower limit of condition (19) to 22.00°, 24.00°, and 26.00°, and further to 27.00°, the effects of each embodiment can be obtained more reliably. Furthermore, by setting the upper limit of condition (19) to 38.00°, 37.00°, and further to 36.00°, the effects of each embodiment can be obtained more reliably.

[0161] The optical system OL of the first and second embodiments preferably satisfies the following conditional expression (20).

[0162] 0.08 <Bf / f<1.20…(20)

[0163] Where Bf: the back focal length of the optical system OL

[0164] f: Focal length of the optical system OL

[0165] Condition (20) specifies an appropriate relationship between the back focal length and the focal length of the optical system OL. By satisfying condition (20), the generation of various aberrations is well suppressed, and an optical system with a short back focal length can be obtained. By setting the lower limit of condition (20) to 0.09, 0.10, 0.11, and further to 0.12, the effects of each embodiment can be obtained more reliably. In addition, by setting the upper limit of condition (20) to 1.18, 1.15, 1.13, 1.10, 1.08, 1.05, and further to 1.03, the effects of each embodiment can be obtained more reliably.

[0166] Next, refer to Figure 23 The manufacturing method of the optical system OL according to the first embodiment will be summarized. First, the front group GA, the aperture (aperture stop) S, and the rear group GB are arranged sequentially along the optical axis from the object side (step ST1). Next, a first focusing lens group GF1 with negative optical power is arranged on the object side of the rear group GB, and a second focusing lens group GF2 with negative optical power is arranged on the image plane side of the rear group GB compared to the first focusing lens group GF1 (step ST1).

[0167] ST2). Furthermore, the lenses are arranged within the lens barrel in such a manner that, when focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move along the optical axis towards the image plane along different trajectories (step ST3). According to this manufacturing method, it is possible to manufacture an optical system with minimal aberration during focusing.

[0168] Next, refer to Figure 24 The manufacturing method of the optical system OL according to the second embodiment will be summarized. First, along the optical axis from the object side, a front lens group GA1 with positive optical power, a first focusing lens group GF1 with negative optical power, a positive lens group GP with positive optical power, a second focusing lens group GF2 with negative optical power, and a final lens group GE are arranged sequentially (step ST11). Furthermore, each lens is arranged within the lens barrel such that, when focusing from an object at infinity to a closer object, the first focusing lens group GF1 and the second focusing lens group GF2 move along the optical axis towards the image plane along different trajectories (step ST12). According to this manufacturing method, an optical system with minimal aberration during focusing can be manufactured.

[0169] Example

[0170] Hereinafter, the optical system OL of each embodiment will be described with reference to the accompanying drawings. Furthermore, the embodiments corresponding to the first embodiment are embodiments 1 to 7 and embodiments 10, and the embodiments corresponding to the second embodiment are embodiments 1 to 10. Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13 , Figure 15 , Figure 17 , Figure 19 This is a cross-sectional view showing the structure and power distribution of the optical systems OL{OL(1) to OL(10)} of embodiments 1 to 10. In the cross-sectional views of the optical systems OL(1) to OL(10) of embodiments 1 to 10, arrows indicate the direction of movement of each lens group along the optical axis when focusing from infinity to a near object. In the cross-sectional view of the optical system OL(10) of embodiment 10, arrows indicate the direction of movement of each lens group along the optical axis when zooming from the wide-angle end state (W) to the telephoto end state (T).

[0171] In these figures ( Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13 , Figure 15 , Figure 17 , Figure 19In this embodiment, each lens group is represented by a combination of the symbol G and a number, and each lens is represented by a combination of the symbol L and a number. To prevent the use of symbols and numbers from becoming too complex due to their large number of types and digits, a separate combination of symbols and numbers is used to represent the lens group, etc., for each embodiment. Therefore, even if the same combination of symbols and numbers is used across embodiments, it does not necessarily mean that they are identical structures.

[0172] Tables 1 through 10 are shown below. Table 1 shows the parameter data in the first embodiment, Table 2 shows the parameter data in the second embodiment, Table 3 shows the parameter data in the third embodiment, Table 4 shows the parameter data in the fourth embodiment, Table 5 shows the parameter data in the fifth embodiment, Table 6 shows the parameter data in the sixth embodiment, Table 7 shows the parameter data in the seventh embodiment, Table 8 shows the parameter data in the eighth embodiment, Table 9 shows the parameter data in the ninth embodiment, and Table 10 shows the parameter data in the tenth embodiment. In each embodiment, the d-line (wavelength λ = 587.6 nm) and the g-line (wavelength λ = 435.8 nm) are selected as the objects for calculating aberration characteristics.

[0173] In the [Overall Parameters] table, f represents the focal length of the entire lens system, FNO represents the F-number, 2ω represents the field of view (in degrees, ω is the half field of view), and Y represents the image height. TL represents the distance along the optical axis from the front of the lens to the rear surface of the lens when focusing at infinity, plus the distance Bf. Bf represents the distance along the optical axis from the rear surface of the lens to image plane I when focusing at infinity (back focal length). Additionally, TL(a) represents the distance along the optical axis of the optical system from the lens surface closest to the object to image plane I when focusing at infinity (air equivalent distance). Bf(a) represents the distance along the optical axis of the optical system from the lens surface closest to the image plane to image plane I when focusing at infinity (air equivalent distance). Furthermore, in the case of a zoom optical system, these values ​​are shown for each zoom state at the wide-angle end (W), intermediate focal length (M), and telephoto end (T).

[0174] Additionally, in the [Overall Parameters] table, fA represents the focal length of the front lens group. fB represents the combined focal length compared to the lens group positioned on the image plane side of the first focusing lens group. βF1 represents the lateral magnification of the first focusing lens group when focusing on an object at infinity. βF2 represents the lateral magnification of the second focusing lens group when focusing on an object at infinity. MF1 represents the absolute value of the movement of the first focusing lens group when focusing from an object at infinity to a closer object. MF2 represents the absolute value of the movement of the second focusing lens group when focusing from an object at infinity to a closer object.

[0175] In the [Lens Parameters] table, the surface number indicates the order of the optical surfaces from the object side along the direction of light travel; R represents the radius of curvature of each optical surface (the surface with the center of curvature on the image side is positive); D represents the distance on the optical axis from each optical surface to the next optical surface (or image surface), i.e., the surface spacing; nd represents the refractive index of the optical component material with respect to the d-line; and νd represents the Abbe number of the optical component material with respect to the d-line. "∞" for the radius of curvature indicates a plane or opening; (aperture S) indicates the aperture stop S. The refractive index of air, nd = 1.00000, is omitted.

[0176] In the [Variable Interval Data] table, the plane interval at plane number i with plane interval (Di) is shown in the [Lens Parameters] table. If the optical system is not a zoom optical system, in the [Variable Interval Data] table, f represents the focal length of the entire lens system, and β represents the magnification. Additionally, D0 represents the distance from the object to the optical surface closest to the object in the optical system. If the optical system is a zoom optical system, in the [Variable Interval Data] table, the plane interval at plane number i with plane interval (Di) corresponding to each zoom state (wide-angle (W), intermediate focal length (M), and telephoto (T)) in the [Lens Parameters] table is shown.

[0177] The table in [Lens Group Data] shows the initial plane (the plane closest to the object) and focal length of each lens group.

[0178] In all parameter values ​​below, the focal length f, radius of curvature R, interplanar spacing D, and other lengths will generally be expressed in "mm" unless otherwise specified. However, the same optical performance can be obtained even if the optical system is scaled up or down, so it is not limited to this.

[0179] The descriptions of the tables up to this point are the same in all embodiments, and repeated descriptions are omitted below.

[0180] (First Embodiment)

[0181] use Figures 1-2 Table 1 describes the first embodiment. Figure 1This is a diagram illustrating the lens structure of the optical system of the first embodiment. The optical system OL(1) of the first embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed. The symbols (+) or (-) attached to the markings of each lens group indicate the optical power of each lens group, which is the same in all the following embodiments.

[0182] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0183] The first lens group G1 consists of a combined lens formed by joining a convex positive meniscus lens L11, a convex positive meniscus lens L12, a convex positive meniscus lens L13, and a convex negative meniscus lens L14, arranged sequentially along the optical axis from the object side, along with a convex negative meniscus lens L15 and a convex positive meniscus lens L16. The second lens group G2 consists of a convex negative meniscus lens L21.

[0184] The third lens group G3 consists of a combined lens formed by joining a biconcave negative lens L31 and a biconvex positive lens L32 arranged sequentially along the optical axis from the object side, a biconvex positive lens L33, and a biconvex positive lens L34. The fourth lens group G4 consists of a biconcave negative lens L41.

[0185] The fifth lens group G5 consists of a combined lens formed by joining a biconvex positive lens L51 (arranged sequentially along the optical axis from the object side) and a negative meniscus lens L52 (with its concave surface facing the object side), and a negative meniscus lens L53 (with its concave surface facing the object side). An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0186] Table 1 below shows the values ​​of the parameters of the optical system of the first embodiment.

[0187] (Table 1)

[0188] [Overall Parameters]

[0189]

[0190] [Lens Parameters]

[0191]

[0192]

[0193] [Variable Interval Data]

[0194]

[0195]

[0196] [Lens Group Data]

[0197]

[0198] Figure 2 (A) is a diagram of aberrations when the optical system of the first embodiment is focused at infinity. Figure 2 (B) is an aberration diagram of the optical system of the first embodiment during close-range focusing. In the aberration diagrams during infinity focusing, FNO represents the F-value and Y represents the image height. In the aberration diagrams during close-range focusing, NA represents the numerical aperture and Y represents the image height. Additionally, the spherical aberration diagram shows the F-value or numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and distortion diagram show the maximum image height, and the coma diagram shows the values ​​of each image height. d represents the d-line (wavelength λ = 587.6 nm), and g represents the g-line (wavelength λ = 435.8 nm). In the astigmatism diagram, solid lines represent the sagittal image plane, and dashed lines represent the meridional image plane. Furthermore, the same symbols as in this embodiment are used in the aberration diagrams of the embodiments shown below, and repeated descriptions are omitted.

[0199] As can be seen from the various aberration diagrams, the optical system of the first embodiment effectively corrects various aberrations throughout the entire region from focusing at infinity to focusing at close range, and has excellent imaging performance.

[0200] (Second Embodiment)

[0201] use Figures 3-4 Table 2 illustrates the second embodiment. Figure 3This is a diagram illustrating the lens structure of the optical system of the second embodiment. The optical system OL(2) of the second embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0202] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0203] The first lens group G1 consists of a combined lens formed by joining a positive meniscus lens L11 (convex side facing the object), a positive meniscus lens L12 (convex side facing the object), a positive lens L13 (biconvex), and a negative lens L14 (biconcave), arranged sequentially along the optical axis from the object side, and a positive meniscus lens L15 (convex side facing the object). The second lens group G2 consists of a negative meniscus lens L21 (convex side facing the object).

[0204] The third lens group G3 consists of a combined lens formed by joining a negative meniscus lens L31 (convex side facing the object) and a positive meniscus lens L32 (convex side facing the object), arranged sequentially along the optical axis from the object side, and a biconvex positive lens L33. The fourth lens group G4 consists of a negative meniscus lens L41 (convex side facing the object).

[0205] The fifth lens group G5 consists of a positive meniscus lens L51 with its convex surface facing the object side and a negative meniscus lens L52 with its concave surface facing the object side, arranged sequentially along the optical axis from the object side. An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0206] Table 2 below shows the values ​​of the parameters of the optical system of the second embodiment.

[0207] (Table 2)

[0208] [Overall Parameters]

[0209]

[0210] [Lens Parameters]

[0211]

[0212]

[0213] [Variable Interval Data]

[0214]

[0215] [Lens Group Data]

[0216]

[0217] Figure 4 (A) is a diagram of aberrations when the optical system of the second embodiment is focused at infinity. Figure 4 (B) is an aberration diagram of the optical system of the second embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the second embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0218] (Third Embodiment)

[0219] use Figures 5-6 Table 3 illustrates the third embodiment. Figure 5 This is a diagram illustrating the lens structure of the optical system of the third embodiment. The optical system OL(3) of the third embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0220] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0221] The first lens group G1 consists of a combined lens consisting of a positive meniscus lens L11 with its convex surface facing the object, a positive meniscus lens L12 with its convex surface facing the object, a biconvex positive lens L13, and a biconcave negative lens L14, arranged sequentially along the optical axis from the object side. The second lens group G2 consists of a negative meniscus lens L21 with its convex surface facing the object.

[0222] The third lens group G3 consists of a biconvex positive lens L31. The fourth lens group G4 consists of a negative meniscus lens L41 with its convex surface facing the object.

[0223] The fifth lens group G5 consists of a positive meniscus lens L51 with its convex surface facing the object side and a negative meniscus lens L52 with its concave surface facing the object side, arranged sequentially along the optical axis from the object side. An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0224] Table 3 below shows the values ​​of the parameters of the optical system of the third embodiment.

[0225] (Table 3)

[0226] [Overall Parameters]

[0227]

[0228] [Lens Parameters]

[0229]

[0230]

[0231] [Variable Interval Data]

[0232]

[0233] [Lens Group Data]

[0234]

[0235] Figure 6 (A) is a diagram of aberrations when the optical system of the third embodiment is focused at infinity. Figure 6 (B) is an aberration diagram of the optical system of the third embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the third embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0236] (Example 4)

[0237] use Figures 7-8 Table 4 illustrates the fourth embodiment. Figure 7 This is a diagram illustrating the lens structure of the optical system of the fourth embodiment. The optical system OL(4) of the fourth embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0238] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0239] The first lens group G1 consists of a combined lens formed by joining a positive meniscus lens L11 (convex side facing the object), a positive meniscus lens L12 (convex side facing the object), and a negative meniscus lens L13 (convex side facing the object), arranged sequentially along the optical axis from the object side, and a combined lens formed by joining a biconvex positive lens L14 and a biconcave negative lens L15. The second lens group G2 consists of a negative meniscus lens L21 (convex side facing the object).

[0240] The third lens group G3 consists of a negative meniscus lens L31 with its concave surface facing the object side, a positive meniscus lens L32 with its concave surface facing the object side, and a biconvex positive lens L33 arranged sequentially along the optical axis from the object side. The fourth lens group G4 consists of a negative meniscus lens L41 with its convex surface facing the object side.

[0241] The fifth lens group G5 consists of a negative meniscus lens L51 with its convex surface facing the object, a positive meniscus lens L52 with its convex surface facing the object, and a negative meniscus lens L53 with its concave surface facing the object, arranged sequentially along the optical axis from the object side. An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0242] Table 4 below shows the values ​​of the parameters of the optical system of the fourth embodiment.

[0243] (Table 4)

[0244] [Overall Parameters]

[0245]

[0246] [Lens Parameters]

[0247]

[0248]

[0249] [Variable Interval Data]

[0250]

[0251]

[0252] [Lens Group Data]

[0253]

[0254] Figure 8 (A) is a diagram of aberrations when the optical system of the fourth embodiment is focused at infinity. Figure 8 (B) is an aberration diagram of the optical system of the fourth embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the fourth embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0255] (5th embodiment)

[0256] use Figures 9-10 Table 5 illustrates the fifth embodiment. Figure 9This is a diagram illustrating the lens structure of the optical system of the fifth embodiment. The optical system OL(5) of the fifth embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0257] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0258] The first lens group G1 consists of a combined lens formed by joining a positive meniscus lens L11 (convex side facing the object), a biconvex positive lens L12, and a biconcave negative lens L13, arranged sequentially along the optical axis from the object side; and a combined lens formed by joining a negative meniscus lens L14 (convex side facing the object) and a positive meniscus lens L15 (convex side facing the object). The second lens group G2 consists of a combined lens with negative optical power formed by joining a positive meniscus lens L21 (concave side facing the object) and a biconcave negative lens L22, arranged sequentially from the object side.

[0259] The third lens group G3 consists of a biconvex positive lens L31 arranged sequentially along the optical axis from the object side and a negative meniscus lens L32 with its concave surface facing the object side. The fourth lens group G4 consists of a combined lens with negative optical power, consisting of a biconvex positive lens L41 and a biconcave negative lens L42 joined together from the object side.

[0260] The fifth lens group G5 consists of a combined lens formed by joining a negative meniscus lens L51 (convex side facing the object) and a positive biconvex lens L52, arranged sequentially along the optical axis from the object side, and a negative meniscus lens L53 (concave side facing the object). An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0261] Table 5 below shows the values ​​of the parameters of the optical system of the fifth embodiment.

[0262] (Table 5)

[0263] [Overall Parameters]

[0264]

[0265]

[0266] [Lens Parameters]

[0267]

[0268]

[0269] [Variable Interval Data]

[0270]

[0271] [Lens Group Data]

[0272]

[0273] Figure 10 (A) is a diagram of aberrations when the optical system of the fifth embodiment is focused at infinity. Figure 10 (B) is an aberration diagram of the optical system of the fifth embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the fifth embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0274] (Sixth Embodiment)

[0275] use Figures 11-12 Table 6 describes the sixth embodiment. Figure 11 This is a diagram illustrating the lens structure of the optical system of the sixth embodiment. The optical system OL(6) of the sixth embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0276] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0277] The first lens group G1 consists of a combined lens formed by joining a convex positive meniscus lens L11, L12, L13 (convex towards the object side), and a negative meniscus lens L14 (convex towards the object side) arranged sequentially along the optical axis from the object side, a negative meniscus lens L15 (convex towards the object side), and a positive meniscus lens L16 (convex towards the object side). The second lens group G2 consists of a negative meniscus lens L21 (convex towards the object side) and a negative meniscus lens L16 (convex towards the object side) arranged sequentially from the object side.

[0278] L22 is composed of a bonded lens with negative optical power.

[0279] The third lens group G3 consists of a combined lens formed by joining a biconcave negative lens L31 and a biconvex positive lens L32 arranged sequentially along the optical axis from the object side, a positive meniscus lens L33 with its convex surface facing the object side, and a biconvex positive lens L34. The fourth lens group G4 consists of a negative meniscus lens L41 with its convex surface facing the object side.

[0280] The fifth lens group G5 consists of a combined lens formed by joining a biconvex positive lens L51 (arranged sequentially along the optical axis from the object side) and a negative meniscus lens L52 (with its concave surface facing the object side), and a negative meniscus lens L53 (with its concave surface facing the object side). An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0281] Table 6 below shows the values ​​of the parameters of the optical system of the sixth embodiment.

[0282] (Table 6)

[0283] [Overall Parameters]

[0284]

[0285] [Lens Parameters]

[0286]

[0287]

[0288] [Variable Interval Data]

[0289]

[0290]

[0291] [Lens Group Data]

[0292]

[0293] Figure 12 (A) is a diagram of aberrations when the optical system of the sixth embodiment is focused at infinity. Figure 12 (B) is an aberration diagram of the optical system of the sixth embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the sixth embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0294] (Seventh Embodiment)

[0295] use Figures 13-14 Table 7 describes the seventh embodiment. Figure 13 This is a diagram illustrating the lens structure of the optical system of the seventh embodiment. The optical system OL(7) of the seventh embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0296] An aperture stop S is positioned between the first lens group G1 and the second lens group G2. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 constitutes the front group GA, and the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the rear group GB. Furthermore, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0297] The first lens group G1 consists of a combined lens formed by joining a positive meniscus lens L11 (convex side facing the object), a biconvex positive lens L12, and a biconcave negative lens L13, arranged sequentially along the optical axis from the object side; and a combined lens formed by joining a negative meniscus lens L14 (convex side facing the object) and a positive meniscus lens L15 (convex side facing the object). The second lens group G2 consists of a combined lens with negative optical power formed by joining a positive meniscus lens L21 (concave side facing the object) and a biconcave negative lens L22, arranged sequentially from the object side.

[0298] The third lens group G3 consists of a combined lens formed by joining a biconvex positive lens L31 with a negative meniscus lens whose concave surface faces the object side, arranged sequentially along the optical axis from the object side; and a combined lens formed by joining a negative meniscus lens L33 with a convex surface facing the object side and a biconvex positive lens L34. The fourth lens group G4 consists of a combined lens with negative optical power formed by joining a positive meniscus lens L41 with a concave surface facing the object side and a biconcave negative lens L42, arranged sequentially from the object side.

[0299] The fifth lens group G5 consists of a negative meniscus lens L51 with its convex surface facing the object side, a biconvex positive lens L52, and a negative meniscus lens L53 with its concave surface facing the object side, arranged sequentially along the optical axis from the object side. An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0300] Table 7 below shows the values ​​of the parameters of the optical system of the seventh embodiment.

[0301] (Table 7)

[0302] [Overall Parameters]

[0303]

[0304]

[0305] [Lens Parameters]

[0306]

[0307]

[0308] [Variable Interval Data]

[0309]

[0310] [Lens Group Data]

[0311]

[0312] Figure 14(A) is a diagram of aberrations when the optical system of the 7th embodiment is focused at infinity. Figure 14 (B) is an aberration diagram of the optical system of the 7th embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the 7th embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0313] (Embodiment 8)

[0314] use Figures 15-16 Table 8 describes the eighth embodiment. Figure 15 This is a diagram showing the lens structure of the optical system of the eighth embodiment. The optical system OL(8) of the eighth embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0315] The aperture stop S is positioned between the second lens group G2 and the third lens group G3. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0316] The first lens group G1 consists of a combined lens formed by joining a positive meniscus lens L11 (convex side facing the object), a positive meniscus lens L12 (convex side facing the object), a biconvex positive lens L13, and a biconcave negative lens L14, arranged sequentially along the optical axis from the object side, and a positive meniscus lens L15 (convex side facing the object). The second lens group G2 consists of a biconcave negative lens L21.

[0317] The third lens group G3 consists of a biconvex positive lens L31, a biconcave negative lens L32, a biconvex positive lens L33, and a biconvex positive lens L34 arranged sequentially along the optical axis from the object side. The fourth lens group G4 consists of a combined lens with negative optical power, formed by joining a biconcave negative lens L41 and a positive meniscus lens L42 with its convex surface facing the object side, arranged sequentially from the object side.

[0318] The fifth lens group G5 consists of a positive meniscus lens L51 with its convex surface facing the object side and a negative meniscus lens L52 with its concave surface facing the object side, arranged sequentially along the optical axis from the object side. An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0319] Table 8 below shows the values ​​of the parameters of the optical system of the eighth embodiment.

[0320] (Table 8)

[0321] [Overall Parameters]

[0322]

[0323] [Lens Parameters]

[0324]

[0325]

[0326] [Variable Interval Data]

[0327]

[0328] [Lens Group Data]

[0329]

[0330] Figure 16 (A) is a diagram of aberrations when the optical system of the 8th embodiment is focused at infinity. Figure 16 (B) is an aberration diagram of the optical system of the 8th embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the 8th embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0331] (Embodiment 9)

[0332] use Figures 17-18 Table 9 describes the ninth embodiment. Figure 17This is a diagram illustrating the lens structure of the optical system of the 9th embodiment. The optical system OL(9) of the 9th embodiment consists 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 negative optical power, and a fifth lens group G5 with negative optical power, arranged sequentially along the optical axis from the object side. When focusing from an object at infinity to a closer object, the second lens group G2 and the fourth lens group G4 move along the optical axis to the image side with different trajectories (movement amounts), and the spacing between adjacent lens groups changes. In addition, during focusing, the positions of the first lens group G1, the third lens group G3, and the fifth lens group G5 relative to the image plane I are fixed.

[0333] The aperture stop S is positioned between the second lens group G2 and the third lens group G3. During focusing, the aperture stop S is fixed in position relative to the image plane I. In this embodiment, the first lens group G1 corresponds to the front lens group GA1, the second lens group G2 corresponds to the first focusing lens group GF1, the third lens group G3 corresponds to the positive lens group GP, the fourth lens group G4 corresponds to the second focusing lens group GF2, and the fifth lens group G5 corresponds to the final lens group GE.

[0334] The first lens group G1 consists of a combined lens formed by joining a biconvex positive lens L11, a biconvex positive lens L12, and a biconcave negative lens L13 arranged sequentially along the optical axis from the object side, and a positive meniscus lens L14 with its convex surface facing the object side. The second lens group G2 consists of a combined lens with negative optical power formed by joining a biconvex positive lens L21 and a biconcave negative lens L22 sequentially from the object side.

[0335] The third lens group G3 consists of a combined lens formed by joining a biconvex positive lens L31, a biconcave negative lens L32, and a biconvex positive lens L33 arranged sequentially along the optical axis from the object side, and a biconvex positive lens L34. The fourth lens group G4 consists of a combined lens with negative optical power formed by joining a negative meniscus lens L41 with its convex surface facing the object side and a positive meniscus lens L42 with its convex surface facing the object side, arranged sequentially from the object side.

[0336] The fifth lens group G5 consists of a combined lens formed by joining a biconvex positive lens L51 (arranged sequentially along the optical axis from the object side) and a negative meniscus lens L52 (with its concave surface facing the object side), and a negative meniscus lens L53 (with its concave surface facing the object side). An image plane I is positioned on the image side of the fifth lens group G5. A parallel plate PP is positioned between the fifth lens group G5 and the image plane I.

[0337] Table 9 below shows the values ​​of the parameters of the optical system of the ninth embodiment.

[0338] (Table 9)

[0339] [Overall Parameters]

[0340]

[0341] [Lens Parameters]

[0342]

[0343]

[0344] [Variable Interval Data]

[0345]

[0346] [Lens Group Data]

[0347]

[0348] Figure 18 (A) is a diagram of aberrations when the optical system of the 9th embodiment is focused at infinity. Figure 18 (B) is an aberration diagram of the optical system of the 9th embodiment during close-range focusing. As can be seen from the aberration diagram, the optical system of the 9th embodiment effectively corrects aberrations throughout the entire region from infinity focusing to close-range focusing, and has excellent imaging performance.

[0349] (Embodiment 10)

[0350] use Figures 19-21 Table 10 describes the 10th embodiment. Figure 19 This is a diagram illustrating the lens structure of the optical system according to the tenth embodiment. Optical System of the Tenth Embodiment

[0351] OL(10) consists 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 negative optical power, a fifth lens group G5 with positive optical power, a sixth lens group G6 with negative optical power, a seventh lens group G7 with negative optical power, and an eighth lens group G8 with positive optical power, arranged sequentially along the optical axis from the object side. When zooming from the wide-angle end (W) to the telephoto end (T), the first to eighth lens groups G1 to G8 move along the optical axis to the object side, and the spacing between adjacent lens groups changes. In addition, when focusing from an object at infinity to a closer object, the fourth lens group G4 and the sixth lens group G6 move along the optical axis to the image side with different trajectories (movement amounts). In addition, during focusing, the positions of the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G5, the seventh lens group G7, and the eighth lens group G8 relative to the image plane I are fixed.

[0352] An aperture stop S is positioned between the third lens group G3 and the fourth lens group G4. During zooming, the aperture stop S moves along the optical axis together with the third lens group G3. Furthermore, during focusing, the aperture stop S and the third lens group G3 are fixed in position relative to the image plane I. In this embodiment, the first lens group G1, the second lens group G2, and the third lens group G3 constitute the front group GA, and the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 constitute the rear group GB. Additionally, the first lens group G1, the second lens group G2, and the third lens group G3 correspond to the front lens group GA1. The fourth lens group G4 corresponds to the first focusing lens group GF1, the fifth lens group G5 corresponds to the positive lens group GP, and the sixth lens group G6 corresponds to the second focusing lens group GF2. The seventh lens group G7 and the eighth lens group G8 correspond to the final lens group GE.

[0353] In addition, in this embodiment, the values ​​of the parameters corresponding to the above-described conditional expressions (1) to (20) are set to the values ​​of the parameters in the wide-angle state. The focal length of the front lens group GA1 is set to the focal length of the front lens group GA1 in the wide-angle state, that is, the combined focal length of the first lens group G1, the second lens group G2, and the third lens group G3 in the wide-angle state. The focal length of the final lens group GE is set to the focal length of the final lens group GE in the wide-angle state, that is, the combined focal length of the seventh lens group G7 and the eighth lens group G8 in the wide-angle state.

[0354] The first lens group G1 consists of a combined lens formed by joining a negative meniscus lens L11 (convex side facing the object) and a positive biconvex lens L12 arranged sequentially along the optical axis from the object side, and a positive meniscus lens L13 (convex side facing the object). The second lens group G2 consists of a combined lens formed by joining a negative meniscus lens L21 (convex side facing the object) and a negative biconcave lens L22 (convex side facing the object) and a positive meniscus lens L23 (convex side facing the object) arranged sequentially along the optical axis from the object side.

[0355] The third lens group G3 consists of a biconvex positive lens L31 arranged sequentially along the optical axis from the object side and a positive meniscus lens L32 with its convex surface facing the object side. The fourth lens group G4 consists of a negative meniscus lens L41 with its convex surface facing the object side.

[0356] The fifth lens group G5 consists of a combined lens, which is formed by joining a biconvex positive lens L51 and a negative meniscus lens L52 with its concave surface facing the object side, arranged sequentially along the optical axis from the object side; a positive meniscus lens L53 with its concave surface facing the object side; and a biconvex positive lens L54. The sixth lens group G6 consists of a positive meniscus lens L61 with its convex surface facing the object side and a negative meniscus lens L62 with its convex surface facing the object side, arranged sequentially along the optical axis from the object side.

[0357] The 7th lens group G7 consists of a biconcave negative lens L71. The 8th lens group G8 consists of a biconvex positive lens L81. An image plane I is disposed on the image side of the 8th lens group G8. A parallel plate PP is disposed between the 8th lens group G8 and the image plane I.

[0358] Table 10 below shows the values ​​of the parameters of the optical system of the 10th embodiment.

[0359] (Table 10)

[0360] [Overall Parameters]

[0361] Magnification ratio = 3.90

[0362] fA = 62.983 fB = 65.548

[0363] βF1 = 6.538 βF2 = 1.193

[0364] MF1 = 4.361 MF2 = 2.626

[0365]

[0366]

[0367] [Lens Parameters]

[0368]

[0369]

[0370] [Variable Interval Data]

[0371]

[0372]

[0373] [Lens Group Data]

[0374]

[0375] Figure 20 (A) is a diagram of aberrations when focusing at infinity in the wide-angle end state of the optical system of the 10th embodiment. Figure 20 (B) is a diagram of aberrations during close-range focusing in the wide-angle end state of the optical system of the 10th embodiment. Figure 21 (A) is a diagram of aberrations when focusing at infinity in the far focal state of the optical system of the 10th embodiment. Figure 21(B) is an aberration diagram of the optical system of the 10th embodiment during close-range focusing in the telephoto end state. As can be seen from the aberration diagram, the optical system of the 10th embodiment corrects aberrations well not only in the wide-angle end state but also in the telephoto end state, and in the entire region from infinity focusing to close-range focusing, thus exhibiting excellent imaging performance.

[0376] Next, a table of [corresponding values ​​for conditional expressions] is shown below. In this table, the values ​​corresponding to each conditional expression (1) to (20) are shown together for all embodiments (1 to 10). Conditional expression (1) 0.30 <STL / TL<0.90

[0377] Conditional expression (2)0.50 <fA / f<2.00

[0378] Conditional expression (3)0.50 <fA / (-fF1)<1.50

[0379] Conditional expression (4)0.35 <fB / (-fF1)<1.50

[0380] Condition (5) - 2.00 < (-fE) / f < 15.00

[0381] Conditional expression (6)-1.00 <fP / (-fE)<1.50

[0382] Condition (7) 1.10 < (-fF1) / fP < 3.20

[0383] Conditional expression (8)0.30 <fP / f<1.00

[0384] Conditional expression (9)0.10 <fF1 / fF2<2.00

[0385] Conditional expression (10)0.50 <f / (-fF1)<1.80

[0386] Condition (11) - 2.50 < (rF12 + rF11) / (rF12 - rF11) < 0.00 Condition (12) 0.05 <Bf / TL<0.80

[0387] Condition (13) - 0.80 < (rR2 + rR1) ​​ / (rR2 - rR1) ​​< 2.50

[0388] Condition (14) 0.01 < 1 / βF1 < 0.60

[0389] Condition (15) 0.50 < 1 / βF2 < 0.95

[0390] Condition (16){βF1+(1 / βF1)} -2 <0.20

[0391] Condition (17){βF2+(1 / βF2)} -2 ≤0.25

[0392] Conditional expression (18)0.15 <MF2 / MF1<0.80

[0393] Conditional expression (19) 20.00° < 2ω < 40.00°

[0394] Conditional expression (20)0.08 <Bf / f<1.20

[0395] [Conditional values] (Examples 1-4)

[0396]

[0397]

[0398] [Conditional values] (Examples 5-8)

[0399]

[0400]

[0401] [Conditional values] (Examples 9-10)

[0402]

[0403] According to the above embodiments, an optical system with minimal aberration changes during focusing can be achieved.

[0404] The above embodiments illustrate specific examples of the invention of this application, but the invention of this application is not limited to these.

[0405] The following can be appropriately adopted within the range that does not impair the optical performance of the optical system of this embodiment.

[0406] Although embodiments of the optical system in this embodiment show structures with 5 and 8 lens groups, this application is not limited to these and other structures (e.g., 6, 9, etc.) can also be constructed. Specifically, it is also possible to add a lens or lens group to the optical system in this embodiment on the side closest to the object or the side closest to the image plane. In addition, a lens group refers to a portion having at least one lens that is separated by the air gap that changes during focusing or zooming.

[0407] It can also be an image stabilizing lens group that corrects image shake caused by hand tremors by moving the lens group or part of the lens group in a manner that has a component perpendicular to the optical axis, or by rotating (oscillating) in the in-plane direction containing the optical axis.

[0408] The lens surface can be formed from a spherical or flat surface, or from an aspherical surface. When the lens surface is spherical or flat, lens processing and assembly adjustments become easier, preventing degradation of optical performance caused by errors in processing and assembly adjustments, and therefore this is preferred. Furthermore, there is less degradation in rendering performance when the image plane is offset, and this is also preferred.

[0409] When the lens surface is aspherical, the aspherical surface can be any of the following: a ground aspherical surface, a glass-molded aspherical surface formed by molding glass into an aspherical shape using a mold, or a composite aspherical surface formed by molding resin into an aspherical shape on the glass surface. Alternatively, the lens surface can also be a diffractive surface, or the lens can be a refractive index distribution lens (GRIN lens) or a plastic lens.

[0410] Although the aperture stop is preferably positioned between the first lens group and the second lens group, or between the second lens group and the third lens group, or between the third lens group and the fourth lens group, it is also possible to omit the aperture stop component and instead use the lens frame to perform its function.

[0411] In order to reduce glare and ghosting and achieve high contrast optical performance, an antireflective coating with high transmittance in a wide wavelength range can also be applied to each lens surface.

[0412] Label Explanation

[0413] G1 Lens Group 1 G2 Lens Group 2

[0414] G3 is the third lens group, and G4 is the fourth lens group.

[0415] G5 is the 5th lens group, and G6 is the 6th lens group.

[0416] G7 7th lens group; G8 8th lens group

[0417] I Image Plane S Aperture Stop

Claims

1. An optical system, wherein, The optical system consists of a front group, an aperture, and a rear group arranged sequentially along the optical axis from the object side. The front group consists of a front lens group, which is a lens group with positive optical power. The rear group consists of a first focusing lens group with negative optical power, a positive lens group with positive optical power, a second focusing lens group with negative optical power, and a final lens group with negative optical power, arranged sequentially from the object side of the rear group. When focusing from an object at infinity to a closer object, the first focusing lens group and the second focusing lens group move along the optical axis towards the image plane along different trajectories. Both the first focusing lens group and the second focusing lens group consist of one or two lenses. In the front lens group, a single lens with positive optical power is provided on the side closest to the object. The optical system satisfies the following condition: 0.862≤f / (-fF1)<1.80 Where f: the focal length of the optical system. fF1: The focal length of the first focusing lens group.

2. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.30 <STL / TL<0.90 Wherein, STL: the distance along the optical axis from the aperture to the image plane. TL: The total length of the optical system.

3. The optical system according to claim 1, wherein, When focusing from an object at infinity to a closer object, the position of the positive lens group relative to the image plane is fixed.

4. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.50 <fA / f<2.00 Wherein, fA: the focal length of the front lens group. f: The focal length of the optical system.

5. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.50 <fA / (-fF1)<1.50 Wherein, fA: the focal length of the front lens group. fF1: The focal length of the first focusing lens group.

6. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.35 <fB / (-fF1)<1.50 Wherein, fB: the combined focal length of the positive lens group, the second focusing lens group, and the final lens group. fF1: The focal length of the first focusing lens group.

7. The optical system according to claim 1, wherein, The optical system satisfies the following condition: -2.00 < (-fE) / f < 15.00 Where fE: the focal length of the final lens group. f: The focal length of the optical system.

8. The optical system according to claim 1, wherein, The optical system satisfies the following condition: -1.00 <fP / (-fE)<1.50 Where fP: the focal length of the positive lens group. fE: The focal length of the final lens group.

9. The optical system according to claim 3, wherein, The optical system satisfies the following condition: 1.10 < (-fF1) / fP < 3.20 Wherein, fF1: the focal length of the first focusing lens group. fP: The focal length of the positive lens group.

10. The optical system according to claim 3, wherein, The optical system satisfies the following condition: 0.30 <fP / f<1.00 Where fP: the focal length of the positive lens group. f: The focal length of the optical system.

11. The optical system according to claim 3, wherein, The positive lens group has a negative lens, a first positive lens, and a second positive lens arranged sequentially along the optical axis from the object side.

12. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.10 <fF1 / fF2<2.00 Wherein, fF1: the focal length of the first focusing lens group. fF2: The focal length of the second focusing lens group.

13. The optical system according to claim 1, wherein, The first focusing lens group consists of a negative lens component.

14. The optical system according to claim 1, wherein, The optical system satisfies the following condition: -2.50<(rF12+rF11) / (rF12-rF11)<0.00 Wherein, rF11: the radius of curvature of the lens surface closest to the object in the first focusing lens group. rF12: The radius of curvature of the lens surface closest to the image plane of the first focusing lens group.

15. The optical system according to claim 1, wherein, The second focusing lens group consists of a negative lens component.

16. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.05 <Bf / TL<0.80 Wherein, Bf: the back focal length of the optical system. TL: The total length of the optical system.

17. The optical system according to claim 1, wherein, The optical system satisfies the following condition: -0.80<(rR2+rR1) / (rR2-rR1)<2.50 Wherein, rR1: the radius of curvature of the object-side lens surface of the lens positioned closest to the image plane in the optical system. rR2: The radius of curvature of the image-side lens surface of the lens of the optical system located closest to the image surface.

18. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.01<1 / βF1<0.60 Wherein, βF1: the lateral magnification of the first focusing lens group when focusing on an object at infinity.

19. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.50<1 / βF2<0.95 Wherein, βF2: the lateral magnification of the second focusing lens group when focusing on an object at infinity.

20. The optical system according to claim 1, wherein, The optical system satisfies the following condition: {βF1+(1 / βF1)} -2 <0.20 Wherein, βF1: the lateral magnification of the first focusing lens group when focusing on an object at infinity.

21. The optical system according to claim 1, wherein, The optical system satisfies the following condition: {βF2 + (1 / βF2)} -2 ≤ 0.25 Wherein, βF2: the lateral magnification of the second focusing lens group when focusing on an object at infinity.

22. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.15 <MF2 / MF1<0.80 Wherein, MF1: the absolute value of the amount of movement of the first focusing lens group when focusing from an object at infinity to a closer object. MF2: The absolute value of the amount of movement of the second focusing lens group when focusing from an object at infinity to a closer object.

23. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 20.00°<2ω<40.00° Wherein, 2ω: the full field of view of the optical system.

24. The optical system according to claim 1, wherein, The optical system satisfies the following condition: 0.08 <Bf / f<1.20 Wherein, Bf: the back focal length of the optical system. f: The focal length of the optical system.

25. An optical device configured to have the optical system described in any one of claims 1 to 24.

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