Optical system

Abstract

To provide an optical system which corrects well for aberrations such as chromatic aberration and offers reduced weight by appropriately selecting glass materials of lenses constituting each lens group.SOLUTION: An optical system disclosed herein comprises an object-side lens group GF and an image-side lens group GR arranged in order from the object side, and has a lens LA that satisfies a given conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical system suitable for lenses used in imaging devices such as still cameras and video cameras, and projection devices, and relates to an optical system capable of effectively correcting chromatic aberration. [Background technology]

[0002] 2. Description of the Related Art In recent years, with the trend toward higher pixel counts in digital cameras and the like, there has been a demand for strict correction of various aberrations in optical systems used in imaging devices, projection devices, and the like.

[0003] Therefore, optical systems proposed up to now have been proposed that use special low dispersion glass to correct chromatic aberration in the wavelength range from C-line to g-line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-101750 A [Patent Document 2] International Publication No. 2019-07344 [Patent Document 3] JP 2019-152887 A [Patent Document 4] JP 2019-020450 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have the following problems.

[0006] Patent Document 1 proposes a variable magnification optical system that has a wide angle of view at the wide-angle end and suppresses axial chromatic aberration by using special low dispersion glass equivalent to HOYA's FCD1. However, the optical system described in Patent Document 1 has a problem in that the correction of lateral chromatic aberration is insufficient, particularly at the wide-angle end.

[0007] Furthermore, Patent Document 2 proposes an optical system that suppresses axial chromatic aberration while providing a wide angle of view. However, the optical system described in Patent Document 2 has a problem in that color flare is likely to remain from the intermediate angle of view to the periphery of the screen due to a shift in the imaging point in the optical axis direction from the C-line to the F-line.

[0008] Also, Patent Document 3 proposes an optical system that uses special low-dispersion glass equivalent to calcium fluoride to suppress axial chromatic aberration. However, the optical system described in Patent Document 3 has a problem in that the correction of lateral chromatic aberration from g-line to h-line is insufficient.

[0009] Also, Patent Document 4 proposes a variable magnification optical system that suppresses axial chromatic aberration at the telephoto end by using special low dispersion glass equivalent to FCD1 manufactured by HOYA Corporation. However, the variable magnification optical system described in Patent Document 4 has a problem in that the correction of axial chromatic aberration at the wide-angle end and the correction of lateral chromatic aberration at the telephoto end are insufficient.

[0010] The present invention has been made in consideration of at least one of these problems, and has an object to provide an optical system in which various aberrations, such as chromatic aberration, are corrected by appropriately using lens materials. [Means for solving the problem]

[0011] In order to achieve the above object, an optical system according to the present invention includes, in order from an object side, an object-side lens group GF and an image-side lens group GR, the object-side lens group GF having a negative refractive power as a whole, and the image-side lens group GR having a positive refractive power as a whole, At least one of the object-side lens group GF and the image-plane-side lens group GR includes a lens LA that satisfies the following conditional expression (1). (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

[0012] Moreover, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following conditional expression (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

[0013] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, The lens LA is disposed in the object-side lens group GF and has a negative refractive power.

[0014] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, The lens LA is disposed in the image-side lens group GR and has a positive refractive power.

[0015] Furthermore, in the optical system according to the present invention, it is preferable that, when the magnification of the optical system is changed, the lens group spacing between the object side lens group GF and the image plane side lens group GR is maximum when the optical system is in a widest angle state and focused on infinity, or when the magnification of the optical system is not changed, the lens group spacing between adjacent lenses of the optical system is maximum when the optical system is in a focused state on infinity; The lens LA is disposed in the object-side lens group GF and has a negative refractive power.

[0016] Furthermore, in the optical system according to the present invention, it is preferable that, when the magnification of the optical system is changed, the lens group spacing between the object side lens group GF and the image plane side lens group GR is maximum when the optical system is in a widest angle state and focused on infinity, or when the magnification of the optical system is not changed, the lens group spacing between adjacent lenses of the optical system is maximum when the optical system is in a focused state on infinity; The lens LA is disposed in the image-side lens group GR and has a positive refractive power.

[0017] Moreover, the optical system according to the present invention preferably comprises a lens group GFA including the lens LA and having negative refractive power, In the case where the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces which change during the magnification change as boundaries, the lens group GFA is disposed closest to the image surface of the object-side lens group GF, or the lens group GFA is identical to the object-side lens group GF; When the optical system does not change magnification, the lens group GFA is the same as the object-side lens group GF, The lens group GFA is characterized by being composed of four or more lenses.

[0018] In addition, the optical system according to the present invention is preferably characterized in that the object-side lens group GF has an aspheric surface in which the positive refractive power becomes stronger or the negative refractive power becomes weaker at the periphery of the effective light diameter with respect to the optical axis center.

[0019] In addition, the optical system according to the present invention is preferably characterized in that the image-side lens group GR has an aspheric surface in which the positive refractive power becomes weaker or the negative refractive power becomes stronger at the periphery of the effective light diameter relative to the optical axis center.

[0020] In order to achieve the above object, an optical system according to the present invention includes an object-side lens group GF and an image-side lens group GR arranged in this order from an object side, an aperture stop is arranged between the object-side lens group GF and the image-side lens group GR, the object-side lens group GF has positive or negative refractive power as a whole, and the image-side lens group GR has positive refractive power as a whole, At least one of the object-side lens group GF and the image-plane-side lens group GR includes a lens LA that satisfies the following conditional expression (1). (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

[0021] Moreover, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following conditional expression (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

[0022] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, The lens LA is disposed in the object-side lens group GF and has a negative refractive power.

[0023] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, The lens LA is disposed in the image-side lens group GR and has a positive refractive power.

[0024] Furthermore, the optical system according to the present invention is preferably characterized in that, when the optical system is in a widest angle state and focused on infinity when the magnification is changed, or when the optical system is not in a variable magnification state and focused on infinity, the height from the optical axis of an axial marginal ray passing through the aperture stop is higher than the height from the optical axis of an axial marginal ray passing through the optical surface closest to the object of the optical system.

[0025] Moreover, the optical system according to the present invention preferably comprises a lens group GFA including the lens LA and having negative refractive power, When the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces that change during the magnification change as boundaries, the lens group GFA is disposed closest to the object among the lens groups having negative refractive power included in the object-side lens group GF, In the case where the optical system does not change magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces that change during focusing as boundaries, the lens group GFA is disposed closest to the object among the lens groups having negative refractive power included in the object-side lens group GF, The lens group GFA is characterized by being composed of four or more lenses.

[0026] In addition, the optical system according to the present invention is preferably characterized in that the object-side lens group GF has an aspheric surface in which the positive refractive power becomes stronger or the negative refractive power becomes weaker at the periphery of the effective light diameter with respect to the optical axis center.

[0027] In addition, the optical system according to the present invention is preferably characterized in that the image-side lens group GR has an aspheric surface in which the positive refractive power becomes weaker or the negative refractive power becomes stronger at the periphery of the effective light diameter relative to the optical axis center.

[0028] In order to achieve the above object, an optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF and an image-plane-side lens group GR, both of which have positive refractive power, has an aperture stop, and has a lens LA that satisfies the following conditional formula (1): (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

[0029] Moreover, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following conditional expression (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

[0030] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, the lens LA is disposed in the object-side lens group GF and has positive refractive power; It is characterized in that the following conditional expression (3) is satisfied. (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0031] In the optical system according to the present invention, when the magnification of the optical system is changed, it is preferable that the distance between at least the object side lens group GF and the image surface side lens group GR is changed during the magnification change, the lens LA is disposed in the image-side lens group GR and has a negative refractive power; It is characterized in that the following conditional expression (4) is satisfied. (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0032] Furthermore, in the optical system according to the present invention, it is preferable that, when the optical system has a variable magnification, the lens group spacing between the object side lens group GF and the image surface side lens group GR is maximum when the optical system is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, the lens group spacing between the object side lens group GF and the image surface side lens group GR is maximum when the optical system is in a state focused on infinity; the lens LA is disposed in the object-side lens group GF and has positive refractive power; It is characterized in that the following conditional expression (3) is satisfied. (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0033] Furthermore, in the optical system according to the present invention, it is preferable that, when the optical system has a variable magnification, the lens group spacing between the object side lens group GF and the image surface side lens group GR is maximum when the optical system is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, the lens group spacing between the object side lens group GF and the image surface side lens group GR is maximum when the optical system is in a state focused on infinity; the lens LA is disposed in the image-side lens group GR and has a negative refractive power; It is characterized in that the following conditional expression (4) is satisfied. (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0034] Moreover, the optical system according to the present invention is preferably characterized in that it satisfies the following conditional expression (5): (5) 0.40 > DFR / LT > 0.10 however, When the optical system does not change magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR when focused at infinity LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when focused at infinity When the optical system has a variable magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR when focused at infinity in the most telephoto state LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when the lens is in the most telephoto position and focused at infinity.

[0035] In order to achieve the above object, the optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF and an image-plane side lens group GR, both of which have positive refractive power, an aperture stop is disposed between the object-side lens group GF and the image-plane side lens group GR, and has a lens LA that satisfies the following conditional expression (1): (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

[0036] Moreover, the optical system according to the present invention is preferably characterized in that the lens LA satisfies the following conditional expression (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

[0037] In the optical system according to the present invention, the lens LA is preferably disposed in the object-side lens group GF and has a positive refractive power, It is characterized in that the following conditional expression (3) is satisfied. (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0038] In the optical system according to the present invention, the lens LA is preferably disposed in the image-side lens group GR and has a negative refractive power, It is characterized in that the following conditional expression (4) is satisfied. (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0039] Furthermore, the optical system according to the present invention is preferably characterized in that, when the optical system has a variable magnification and is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification and is focused on infinity, the height from the optical axis of an on-axis marginal ray passing through the aperture stop is lower than the height from the optical axis of an on-axis marginal ray passing through the optical surface closest to the object of the optical system.

[0040] Moreover, the optical system according to the present invention is preferably characterized in that it satisfies the following conditional expression (6). (6) 0.70 > HS / HR1 > 0.20 however, When the optical system does not change magnification, HS: Height from the optical axis of the on-axis marginal ray passing through the aperture stop when focused at infinity HR1: Height from the optical axis of the axial marginal ray passing through the optical surface closest to the object in the optical system when focused at infinity When the optical system has a variable magnification, HS: Height from the optical axis of the on-axis marginal ray passing through the aperture stop when the lens is focused at infinity in the most telephoto position HR1: The height from the optical axis of the axial marginal ray passing through the optical surface closest to the object of the optical system when the lens is focused at infinity in the most telephoto state Effect of the Invention

[0041] According to the optical system of the present invention, by appropriately using glass materials for the lenses that constitute each lens group, it is possible to provide an optical system that achieves weight reduction while correcting various aberrations such as chromatic aberration. [Brief description of the drawings]

[0042] [Figure 1] 1 is a lens configuration diagram of a variable magnification optical system according to a first embodiment in a state where the lens is focused on infinity at a wide-angle end. [Diagram 2] 4 is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at the wide-angle end. FIG. [Diagram 3]1 is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at an intermediate focal length. [Figure 4] 4 is a longitudinal aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at the telephoto end. FIG. [Diagram 5] 4 is a lateral aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at the wide-angle end. FIG. [Figure 6] 4 is a lateral aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at an intermediate focal length. FIG. [Figure 7] 4 is a lateral aberration diagram of the variable magnification optical system of Example 1 when focused on infinity at the telephoto end. FIG. [Figure 8] FIG. 11 is a lens configuration diagram of a variable magnification optical system according to a second embodiment in a state where the lens is focused on infinity at the wide-angle end. [Figure 9] 11 is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the wide-angle end. FIG. [Figure 10] 11 is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the intermediate focal length. FIG. [Figure 11] 11 is a longitudinal aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the telephoto end. FIG. [Figure 12] 11 is a lateral aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the wide-angle end. FIG. [Figure 13] 11 is a lateral aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the intermediate focal length. FIG. [Figure 14] 11 is a lateral aberration diagram of the variable magnification optical system of Example 2 when focused on infinity at the telephoto end. FIG. [Figure 15] FIG. 11 is a lens configuration diagram of the optical system of Example 3 when focused at infinity. [Figure 16] FIG. 11 is a longitudinal aberration diagram of the optical system of Example 3 when focused at infinity. [Figure 17] 11A to 11C are longitudinal aberration diagrams of the optical system of Example 3 at a shooting distance of 245 mm. [Figure 18] 11A to 11C are diagrams showing lateral aberration in the optical system of Example 3 when focused at infinity. [Figure 19]11A to 11C are diagrams showing lateral aberration in the optical system of Example 3 at a shooting distance of 245 mm. [Figure 20] FIG. 11 is a lens configuration diagram of the optical system of Example 4 when focused at infinity. [Figure 21] FIG. 13 is a longitudinal aberration diagram of the optical system of Example 4 when focused at infinity. [Figure 22] 13A to 13C are longitudinal aberration diagrams of the optical system of Example 4 at a shooting distance of 230 mm. [Figure 23] 11A to 11C are diagrams showing lateral aberration in the optical system of Example 4 when focused at infinity. [Figure 24] 11A to 11C are diagrams showing lateral aberration in the optical system of Example 4 at a shooting distance of 230 mm. [Diagram 25] FIG. 13 is a lens configuration diagram of a variable magnification optical system according to a fifth embodiment when focused on infinity at the wide-angle end. [Figure 26] 13 is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the wide-angle end. FIG. [Figure 27] 13 is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the intermediate focal length. [Figure 28] 13 is a longitudinal aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the telephoto end. FIG. [Figure 29] 13 is a lateral aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the wide-angle end. FIG. [Diagram 30] 13 is a lateral aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the intermediate focal length. [Diagram 31] 13 is a lateral aberration diagram of the variable magnification optical system of Example 5 when focused on infinity at the telephoto end. [Diagram 32] FIG. 13 is a lens configuration diagram of the optical system of Example 6 when focused at infinity. [Diagram 33] FIG. 13 is a longitudinal aberration diagram of the optical system of Example 6 when focused at infinity. [Diagram 34] 13 is a longitudinal aberration diagram of the optical system of Example 6 at a shooting distance of 2675 mm. [Diagram 35] FIG. 13 is a lateral aberration diagram of the optical system of Example 6 when focused at infinity. [Diagram 36] 13A to 13C are diagrams showing lateral aberration in the optical system of Example 6 at a shooting distance of 2675 mm. [Figure 37] FIG. 13 is a lens configuration diagram of the optical system of Example 7 when focused at infinity. [Figure 38] FIG. 13 is a longitudinal aberration diagram of the optical system of Example 7 when focused at infinity. [Figure 39] 13 is a longitudinal aberration diagram of the optical system of Example 7 at a shooting distance of 800 mm. [Diagram 40] FIG. 13 is a lateral aberration diagram of the optical system of Example 7 when focused at infinity. [Diagram 41] 13A to 13C are diagrams showing lateral aberration in the optical system of Example 7 at a shooting distance of 800 mm. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Hereinafter, examples of the optical system according to the present invention will be described in detail. Note that the explanation of the examples is given as an example of the optical system according to the present invention, and the present invention is not limited to the examples within the scope of the gist of the present invention.

[0044] The object of the present invention is to provide an optical system in which various aberrations such as chromatic aberration are well corrected, and it is important to use appropriate glass materials for each of the lenses that make up the optical system.

[0045] Conventionally, a known method for simultaneously correcting axial chromatic aberration and lateral chromatic aberration is to use glass materials that have small wavelength dispersion of the refractive index and large anomalous dispersion on the short wavelength side near the g-line. However, most such glass materials have a low refractive index, which works against the control of short wavelength aberrations.

[0046] Furthermore, when using a conventional glass material in which the wavelength dispersion of the refractive index is small and the anomalous dispersion on the short wavelength side near the g-line is large, it has been difficult to simultaneously correct axial chromatic aberration and lateral chromatic aberration, or in the case of a variable magnification optical system, to correct chromatic aberration over the entire magnification range.

[0047] For example, calcium fluoride single crystal and low dispersion / anomalous dispersion glass equivalent to HOYA's FCD100 have high Abbe numbers and g-line anomalous dispersion, and are effective in correcting chromatic aberration in the primary and secondary spectra; however, it is difficult to correct chromatic aberration from the C-line to the g-line by using these alone.

[0048] Therefore, the optical system according to the present invention uses glasses equivalent to the low-dispersion oxyfluoride glass described in WO 2017-124612 and the ultra-low dispersion fluoride glass K-FIR100UV manufactured by Sumita Corporation, thereby correcting axial chromatic aberration and chromatic aberration from the C-line to the g-line, while also limiting the number of sheets of special low-dispersion glass used, making it easier to use high refractive index glass in other locations, and also making it possible to suppress various aberrations such as astigmatism.

[0049] The optical system according to the present invention has a lens LA that satisfies the following conditional expression (1). (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

[0050] Conditional formula (1) defines a preferable range for the Abbe number at the d-line of the lens LA in the optical system according to the present invention.

[0051] When the lower limit of conditional formula (1) is exceeded and the Abbe number at the d-line of the lens LA becomes small, the lens LA does not have a sufficient ability to correct chromatic aberration, making it difficult to allocate the effect of correcting single-wavelength aberration to other lenses while correcting chromatic aberration.

[0052] Moreover, by setting the lower limit of condition (1) to 97.00, the effects of the present invention can be achieved more reliably.

[0053] Furthermore, in the optical system according to the present invention, it is desirable that the lens LA satisfy the following conditional expression (2). (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

[0054] Conditional formula (2) defines a preferable range for the partial dispersion ratio for the g-line of the lens LA in the optical system according to the present invention.

[0055] If the lower limit of condition (2) is exceeded and the average value of the deviation ΔθgF of the partial dispersion ratio for the g-line of the lens LA becomes small, it becomes difficult to correct the chromatic aberration of the secondary spectrum.

[0056] Moreover, by setting the lower limit of condition (2) to 0.061, the effect of the present invention can be achieved more reliably.

[0057] Hereinafter, examples of wide-angle to standard type and telephoto type optical systems having a lens LA that satisfies the above-mentioned predetermined conditional expressions will be described. In the present examples, Examples 1 to 4 are examples of wide-angle to standard type optical systems having a lens LA, and Examples 5 to 6 are examples of telephoto type optical systems having a lens LA.

[0058] [First embodiment (wide-angle to standard type optical system)] Examples 1 to 4 of wide-angle to standard-type optical systems having a lens LA will be described.

[0059] A wide-angle to standard type optical system according to the present invention is configured by, arranged in order from the object side, an object-side lens group GF and an image-side lens group GR, where the object-side lens group GF has negative refractive power as a whole and the image-side lens group GR has positive refractive power as a whole, and at least one of the object-side lens group GF or the image-side lens group GR includes a lens LA that satisfies the above-mentioned conditional formula.

[0060] By using such a lens configuration, it becomes easier to ensure the back focus and to suppress vignetting, particularly in an optical system having a wide angle of view.

[0061] Alternatively, a wide-angle to standard type optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF and an image-side lens group GR, with an aperture stop disposed between the object-side lens group GF and the image-side lens group GR, with the object-side lens group GF having positive or negative refractive power as a whole and the image-side lens group GR having positive refractive power as a whole, and with a lens LA that satisfies the above-mentioned conditional expression in at least one of the object-side lens group GF or the image-side lens group GR.

[0062] By using such a lens configuration, it is possible to easily suppress aberration of light rays that enter the periphery of the screen while ensuring back focus, particularly in an optical system having a field angle ranging from wide angle to standard range.

[0063] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the magnification of the optical system is changed, it is desirable that at least the distance between the object-side lens group GF and the image-plane-side lens group GR changes during the magnification change, and that the lens LA is disposed in the object-side lens group GF and has negative refractive power.

[0064] With this lens configuration, lateral chromatic aberration can be effectively corrected both in an optical system that does not change magnification and in each magnification state of an optical system that changes magnification.

[0065] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the magnification of the optical system is changed, it is desirable that at least the distance between the object-side lens group GF and the image-side lens group GR changes during the magnification change, and that the lens LA is disposed in the image-side lens group GR and has positive refractive power.

[0066] With this lens configuration, axial chromatic aberration and lateral chromatic aberration can be effectively corrected both in an optical system that does not change magnification and in each magnification state of an optical system that changes magnification.

[0067] Furthermore, in the wide-angle to standard type optical system of the present invention, when the optical system is in a variable magnification state and focused on infinity at its widest angle, or when the optical system is not variable magnification and focused on infinity, the lens group spacing between the object-side lens group GF and the image-plane-side lens group GR is at its largest among the air spaces between adjacent lenses in the optical system, and it is desirable that the lens LA be disposed in the object-side lens group GF and have negative refractive power.

[0068] With this lens configuration, lateral chromatic aberration can be effectively corrected both in an optical system that does not change magnification and in an optical system that changes magnification at the wide-angle end.

[0069] Furthermore, in the wide-angle to standard type optical system of the present invention, when the optical system is in a variable magnification state and focused on infinity at its widest angle, or when the optical system is not variable magnification and focused on infinity, the lens group spacing between the object-side lens group GF and the image-side lens group GR is at its largest among the air spaces between adjacent lenses in the optical system, and it is desirable that the lens LA be disposed in the image-side lens group GR and have positive refractive power.

[0070] By using such a lens configuration, it is possible to effectively correct axial chromatic aberration and lateral chromatic aberration both in an optical system that does not vary magnification and in an optical system that varies magnification at the wide-angle end.

[0071] Furthermore, in the wide-angle to standard type optical system according to the present invention, when the magnification of the optical system is changed, it is desirable that when the optical system is in the widest angle state and focused on infinity, or when the magnification of the optical system is not changed, when the optical system is focused on infinity, the height from the optical axis of an axial marginal ray passing through the aperture stop is higher than the height from the optical axis of an axial marginal ray passing through the optical surface closest to the object of the optical system.

[0072] By using such a lens configuration, it becomes easier to ensure back focus, both in an optical system that does not change magnification, and also in the wide-angle end of an optical system that changes magnification, and it also becomes easier to suppress peripheral light falloff.

[0073] Furthermore, the wide-angle to standard type optical system according to the present invention has a lens group GFA which includes a lens LA and has negative refractive power, and when the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces which change during magnification as boundaries, the lens group GFA is disposed closest to the image surface of the object-side lens group GF or is identical to the object-side lens group GF; when the optical system does not vary its magnification, the lens group GFA is identical to the object-side lens group GF and it is desirable that the lens group GFA is composed of four or more lenses.

[0074] Alternatively, the wide-angle to standard type optical system according to the present invention has a lens group GFA which includes a lens LA and has negative refractive power, and when the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces which change during magnification as boundaries, the lens group GFA is located closest to the object among the lens groups which have negative refractive power included in the object-side lens group GF, and when the optical system does not vary its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces which change during focusing as boundaries, the lens group GFA is located closest to the object among the lens groups which have negative refractive power included in the object-side lens group GF, and it is preferable that the lens group GFA is composed of four or more lenses.

[0075] With this lens configuration, it is possible to effectively correct various aberrations such as astigmatism as well as chromatic aberration of magnification both in an optical system that does not change magnification and in each magnification state of an optical system that changes magnification.

[0076] Furthermore, in the wide-angle to standard type optical system according to the present invention, it is desirable that the object-side lens group GF has an aspheric surface in which the positive refractive power becomes stronger or the negative refractive power becomes weaker at the periphery of the effective light diameter relative to the center of the optical axis.

[0077] By using such a lens configuration, distortion can be effectively corrected.

[0078] Furthermore, in the wide-angle to standard type optical system according to the present invention, it is desirable that the image-side lens group GR has an aspheric surface in which the positive refractive power becomes weaker or the negative refractive power becomes stronger at the periphery of the effective light diameter relative to the center of the optical axis.

[0079] By using such a lens configuration, various aberrations such as distortion and curvature of field can be effectively corrected.

[0080] [Second embodiment (telephoto type optical system)] A telephoto type optical system having a lens LA according to embodiments 5 to 7 will be described.

[0081] A telephoto type optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF having positive refractive power and an image-plane-side lens group GR, has an aperture stop, and has a lens LA that satisfies the above-mentioned conditional expression.

[0082] Alternatively, a telephoto type optical system according to the present invention is configured by arranging, in order from the object side, an object-side lens group GF and an image-side lens group GR, both of which have positive refractive power, an aperture stop is disposed between the object-side lens group GF and the image-side lens group GR, and has a lens LA that satisfies the above-mentioned conditional expression.

[0083] By using such a lens configuration, it becomes easy to reduce the overall length and the light beam diameter, particularly in a telephoto optical system, thereby making the optical system more compact and lightweight.

[0084] Furthermore, in the telephoto-type optical system according to the present invention, when the magnification of the optical system is changed, it is desirable that at least the distance between the object-side lens group GF and the image-plane-side lens group GR changes during the magnification change, and that the lens LA is disposed in the object-side lens group GF and has positive refractive power.

[0085] With this configuration, it is possible to effectively correct axial chromatic aberration and lateral chromatic aberration both in an optical system that does not change magnification and in each magnification state of an optical system that changes magnification.

[0086] It is also desirable to satisfy the following condition (3): (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0087] Condition (3) defines a preferable range for the distance on the optical axis between the aperture stop and the image-plane side surface of the lens LA arranged in the object-side lens group GF.

[0088] When the lower limit of conditional formula (3) is exceeded and the distance on the optical axis between the aperture stop and the image-plane side surface of the lens LA arranged in the object-side lens group GF becomes small, it becomes difficult to effectively correct axial chromatic aberration and lateral chromatic aberration.

[0089] Furthermore, in the telephoto type optical system according to the present invention, when the magnification of the optical system is changed, it is desirable that at least the distance between the object side lens group GF and the image side lens group GR changes during the magnification change, and that the lens LA is disposed in the image side lens group GR and has negative refractive power.

[0090] With this configuration, lateral chromatic aberration can be effectively corrected both in an optical system that does not change magnification and in each magnification state of an optical system that changes magnification.

[0091] It is also desirable to satisfy the following condition (4): (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

[0092] Condition (4) defines a preferable range for the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-plane side lens group GR.

[0093] When the lower limit of conditional formula (4) is exceeded and the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-plane side lens group GR becomes small, it becomes difficult to effectively correct lateral chromatic aberration.

[0094] Furthermore, in the telephoto-type optical system according to the present invention, when the optical system has a variable magnification and is in the most telephoto state and focused on infinity, or when the optical system does not have a variable magnification and is focused on infinity, the lens group spacing between the object-side lens group GF and the image-plane-side lens group GR is maximum among the air spaces between adjacent lenses in the optical system, and it is desirable that the lens LA be disposed in the object-side lens group GF and have positive refractive power.

[0095] With this configuration, axial chromatic aberration and lateral chromatic aberration can be effectively corrected both in an optical system that does not vary magnification and in an optical system that varies magnification at the telephoto end.

[0096] Furthermore, in the telephoto-type optical system according to the present invention, when the optical system has a variable magnification and is in the most telephoto state and focused on infinity, or when the optical system does not have a variable magnification and is focused on infinity, the lens group spacing between the object-side lens group GF and the image-side lens group GR is maximum among the air spaces between adjacent lenses in the optical system, and it is desirable that the lens LA be disposed in the image-side lens group GR and have negative refractive power.

[0097] With this configuration, lateral chromatic aberration can be effectively corrected both in an optical system that does not change magnification and in an optical system that changes magnification at the telephoto end.

[0098] Furthermore, it is desirable for the telephoto optical system according to the present invention to satisfy the following conditional expression (5). (5) 0.40 > DFR / LT > 0.10 however, When the optical system does not change magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR when focused at infinity LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when focused at infinity When the optical system has a variable magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR when focused at infinity in the most telephoto state LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when the lens is in the most telephoto position and focused at infinity.

[0099] Condition (5) defines a preferable range for the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR.

[0100] If the upper limit of conditional expression (5) is exceeded and the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR becomes large, it becomes difficult to effectively use the portion of the limited overall optical length that is occupied by this air gap for aberration correction, making it difficult to correct various aberrations such as distortion while achieving a reduction in the overall length of the optical system.

[0101] If the lower limit of conditional formula (5) is exceeded and the air gap on the optical axis between the object-side lens group GF and the image-plane-side lens group GR becomes small, a large number of lenses will be arranged at locations where the light rays are high, making it difficult to reduce the weight of the optical system.

[0102] Moreover, by setting the upper limit of condition (5) to 0.36, the effect of the present invention can be achieved more reliably.

[0103] Moreover, by setting the lower limit of condition (5) to 0.14, the effect of the present invention can be achieved more reliably.

[0104] Furthermore, in the telephoto-type optical system according to the present invention, when the optical system has a variable magnification, and when the optical system is in the most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, and when the optical system is focused on infinity, it is desirable that the height from the optical axis of an axial marginal ray passing through the aperture stop is lower than the height from the optical axis of an axial marginal ray passing through the optical surface closest to the object of the optical system.

[0105] With this configuration, it is possible to easily reduce the overall length of the optical system and the diameter of the aperture stop, both in an optical system that does not vary magnification, and in an optical system that varies magnification, at the telephoto end.

[0106] Furthermore, it is desirable for the telephoto optical system according to the present invention to satisfy the following condition (6): (6) 0.70 > HS / HR1 > 0.20 however, When the optical system does not change magnification, HS: Height from the optical axis of the on-axis marginal ray passing through the aperture stop when focused at infinity HR1: Height from the optical axis of the axial marginal ray passing through the optical surface closest to the object in the optical system when focused at infinity When the optical system has a variable magnification, HS: Height from the optical axis of the on-axis marginal ray passing through the aperture stop when the lens is focused at infinity in the most telephoto position HR1: The height from the optical axis of the axial marginal ray passing through the optical surface closest to the object of the optical system when the lens is focused at infinity in the most telephoto state

[0107] Conditional formula (6) defines a preferable range for the ratio of the height from the optical axis of an axial marginal ray passing through the aperture stop to the height from the optical axis of an axial marginal ray passing through the optical surface closest to the object in the optical system.

[0108] If the upper limit of condition (6) is exceeded and the height from the optical axis of the on-axis marginal ray passing through the aperture stop becomes relatively large, mechanisms such as the variable stop will become larger and it will become difficult to suppress the overall length of the optical system relative to the focal length.

[0109] If the lower limit of condition (6) is exceeded and the height from the optical axis of the on-axis marginal ray passing through the aperture stop becomes relatively low, a surface with extremely strong refractive power will be required to strongly refract the on-axis marginal ray, which will not only worsen various aberrations such as spherical aberration but will also make it more likely that performance will deteriorate due to decentering, etc.

[0110] Moreover, by setting the upper limit of condition (6) to 0.60, the effect of the present invention can be achieved more reliably.

[0111] Moreover, by setting the lower limit of condition (6) to 0.25, the effect of the present invention can be achieved more reliably.

[0112] The following describes the lens configurations, numerical examples, and corresponding values ​​of conditional expressions for the wide-angle to standard type optical system and the telephoto type optical system according to the present invention. Note that in the following description, the lens configurations are described in order from the object side to the image surface side.

[0113] In [Surface Data], the surface number is the lens surface or aperture stop number counted from the object side, r is the radius of curvature of each lens surface, d is the spacing between each lens surface, nd is the refractive index for the d-line (wavelength 587.56 nm), vd is the Abbe number for the d-line, and θgF is the partial dispersion ratio between the g-line (wavelength 435.84 nm) and the F-line (wavelength 486.13 nm).

[0114] An asterisk (*) next to a surface number indicates that the lens surface is aspheric. BF is the back focus, and the object distance is the distance from the subject to the first lens surface.

[0115] The (diaphragm) next to a surface number indicates that an aperture diaphragm is located at that position. The radius of curvature for the plane or aperture diaphragm is marked as ∞ (infinity).

[0116] [Aspheric Data] shows the values ​​of each coefficient that gives the aspheric shape of the lens surface marked with an * in [Surface Data]. The shape of the aspheric surface is expressed by the following formula. In the formula below, the displacement from the optical axis in the direction perpendicular to the optical axis is represented by y, the displacement (sag amount) from the intersection of the aspheric surface and the optical axis in the direction of the optical axis is represented by z, the radius of curvature of the reference sphere is represented by r, and the Conic coefficient is represented by K. Additionally, the aspheric coefficients of the 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th, 15th, and 16th orders are represented by A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, and A16, respectively.

[0117]

number

[0118] [Various Data] shows values ​​such as focal length at each focal length state or each shooting distance focus state.

[0119] [Variable Distance Data] shows the variable distance and BF values ​​for each focal length state or each shooting distance focus state.

[0120] [Lens Group Data] shows the surface number of each lens group closest to the object and the composite focal length of the entire group.

[0121] In addition, in the aberration diagrams corresponding to the respective embodiments, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and the meridional image surface, respectively.

[0122] In addition, for all of the values ​​of the following specifications, the focal length f, radius of curvature r, lens surface spacing d, and other length units are given in millimeters (mm) unless otherwise specified; however, since the optical system provides equivalent optical performance with proportional magnification and proportional reduction, this is not limited to this. EXAMPLES

[0123] FIG. 1 is a lens configuration diagram of a variable magnification optical system according to a first embodiment of the present invention.

[0124] The variable magnification optical system of the first embodiment is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. When changing magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 increases and then decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases. The sixth lens group G6 is fixed with respect to the image surface during the change of magnification.

[0125] The composite group consisting of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF in claims 1 to 6, the composite group consisting of the third lens group G3 to the sixth lens group G6 corresponds to the image-plane-side lens group GR in claims 1 to 6, and the second lens group G2 corresponds to the lens group GFA including the lens LA in claim 7.

[0126] The composite group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF in claims 10 to 14, the composite group of the third lens group G3 to the sixth lens group G6 corresponds to the image-plane-side lens group GR in claims 10 to 14, and the second lens group G2 corresponds to the lens group GFA including the lens LA in claim 15.

[0127] An aperture diaphragm S is disposed between the second lens group G2 and the third lens group G3.

[0128] The first lens group G1 is composed of, in order from the object side, a cemented lens made of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0129] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens consisting of a biconcave lens L5 and a biconvex lens L6, a biconvex lens L7, and a negative meniscus lens L8 with a convex surface facing the image side, and the lens surfaces on both sides of the negative meniscus lens L4 have a predetermined aspheric shape. The negative meniscus lens L8 corresponds to the lens LA in this invention.

[0130] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L9 with a convex surface facing the object side, a cemented lens made up of a positive meniscus lens L10 with a convex surface facing the object side and a negative meniscus lens L11 with a convex surface facing the object side, and a cemented lens made up of a negative meniscus lens L12 with a convex surface facing the object side and a positive meniscus lens L13 with a convex surface facing the object side, and the lens surfaces on both sides of the positive meniscus lens L9 have a predetermined aspheric shape. The positive meniscus lens L13 corresponds to the lens LA in this invention.

[0131] The fourth lens group G4 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens L14 with its convex surface facing the object side and a biconvex lens L15, and a biconvex lens L16, both lens surfaces of which have a predetermined aspheric shape. The biconvex lens L15 corresponds to the lens LA in this invention.

[0132] The fifth lens group G5 is composed solely of a negative meniscus lens L17 having a convex surface facing the object side, in that order from the object side. The fifth lens group G5 moves as a whole toward the image surface side during focusing from an infinity object distance to a close distance.

[0133] The sixth lens group G6 is composed of a biconvex lens L18, a biconcave lens L19, and a negative meniscus lens L20 with its convex surface facing the image surface side, and both lens surfaces of the negative meniscus lens L20 have a predetermined aspheric shape.

[0134] The specifications of the optical system according to the first embodiment are shown below. Numerical Example 1 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1 672.5318 2.5000 1.92286 20.88 0.638840 2 223.7090 8.2551 1.55032 75.50 0.539881 3 -354.6280 0.1500 4 72.3861 8.5434 1.75500 52.32 0.547242 5 225.2088 (d5) 6* 212.1689 2.3000 1.77250 49.50 0.551804 7* 23.4631 10.4743 8 -37.5554 1.6635 1.59282 68.62 0.544009 9 26.8746 7.2057 1.75500 52.32 0.547242 10 -259.9052 0.1500 11 770.2718 3.3191 2.00100 29.13 0.599373 12 -100.6859 3.1153 13 -29.5029 0.9000 1.41390 100.82 0.533605 14 -80.2315 (d14) 15(Aperture) ∞ 1.5000 16* 54.1542 3.3572 1.55332 71.68 0.540167 17* 133.5316 0.1500 18 35.6379 5.4355 1.92286 20.88 0.638840 19 100.5624 1.1000 1.77047 29.74 0.594996 20 38.9981 0.3135 21 39.6115 1.1000 1.85451 25.15 0.610160 22 23.3180 7.4617 1.41390 100.82 0.533605 23 103.9434 (d23) 24 68.3190 1.2000 1.85451 25.15 0.610160 25 31.5332 7.7102 1.41390 100.82 0.533605 26 -151.3755 0.2323 27* 34.4957 10.1222 1.59201 67.02 0.535765 28* -38.5287 (d28) 29 84.1341 0.9000 1.91082 35.25 0.582104 30 29.1111 (d30) 31 139.8664 6.4702 2.00100 29.13 0.599373 32 -48.4533 0.1500 33 -62.5586 0.9000 1.73037 32.23 0.589819 34 153.1720 4.9045 35* -47.2352 1.3500 1.58313 59.46 0.540428 36* -145.3412 (BF) Image plane ∞ [Aspheric data] 6th 7th 16th 17th K 0.00000 0.00000 0.00000 0.00000 A4 2.51576E-07 -2.94360E-06 -3.49364E-06 7.49274E-08 A6 1.94291E-08 1.97402E-08 1.20715E-08 1.57632E-08 A8 -7.87263E-11 -2.23590E-11 -9.32398E-12 -7.62943E-12 A10 1.86394E-13 -8.03218E-14 -3.44187E-14 -3.63402E-14 A12 -2.35091E-16 3.29341E-16 0.00000E+00 0.00000E+00 A14 1.29558E-19 0.00000E+00 0.00000E+00 0.00000E+00 27th page 28th page 35th page 36th page K 0.00000 0.00000 0.00000 0.00000 A4 -7.54571E-06 5.24520E-06 6.33827E-07 2.39126E-06 A6 -1.04713E-09 -9.06910E-09 -3.85594E-08 -4.11777E-08 A8 2.04182E-12 1.12469E-11 4.89128E-12 3.29571E-11 A10 -1.86264E-14 -1.87968E-14 5.03597E-14 -9.46789E-15 A12 2.67430E-17 1.57087E-17 -6.61740E-17 9.29198E-18 A14 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.34 Wide Angle Mid-Telephoto Focal length 28.90 49.99 67.75 F-number 2.07 2.07 2.07 Full angle of view 2ω 76.74 45.57 33.8 Image height Y 21.63 21.63 21.63 Lens length 169.15 171.89 184.16 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 1.5000 17.2434 31.2233 d14 26.7966 6.2404 2.0000 d23 3.9900 2.5649 1.5000 d28 1.9500 3.6671 2.7564 d30 10.6818 17.9447 22.4440 BF 21.2980 21.2980 21.2980 [Lens group data] Group starting plane focal length G1 1 117.28 G2 6 -29.60 G3 15 79.54 G4 24 31.19 G5 29 -49.26 G6 31 262.47 EXAMPLES

[0135] FIG. 8 is a lens configuration diagram of a variable magnification optical system according to a second embodiment of the present invention.

[0136] The variable magnification optical system of Example 2 is composed of, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power. When varying magnification from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases.

[0137] The first lens group G1 corresponds to the object-side lens group GF in claims 1 to 6 and the lens group GFA including the lens LA in claim 7, and the composite group of the second lens group G2 to the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 1 to 6.

[0138] The composite group of the first lens group G1 to the third lens group G3 corresponds to the object-side lens group GF in claims 10 to 14, the first lens group G1 corresponds to the lens group GFA including the lens LA in claim 15, and the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 10 to 14, respectively.

[0139] An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4.

[0140] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a biconcave lens L3, and a positive meniscus lens L4 with a convex surface facing the object side, and the lens surfaces on both sides of the negative meniscus lens L1 have a predetermined aspheric shape. The biconcave lens L3 corresponds to the lens LA in this invention.

[0141] The second lens group G2 is composed only of a cemented lens made up of a negative meniscus lens L5 with a convex surface facing the object side and a biconvex lens L6. The second lens group G2 moves toward the image surface side during focusing from an infinity object distance to a close distance.

[0142] The third lens group G3 is composed of, in order from the object side, a negative meniscus lens L7 with a convex surface facing the image side, and a cemented lens made up of a negative meniscus lens L8 with a convex surface facing the object side and a biconvex lens L9, and the lens surfaces on both sides of the negative meniscus lens L7 have a predetermined aspheric shape.

[0143] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L10, a cemented lens consisting of a negative meniscus lens L11 with a convex surface facing the object side and a biconvex lens L12, a cemented lens consisting of a biconcave lens L13 and a positive meniscus lens L14 with a convex surface facing the object side, a cemented lens consisting of a negative meniscus lens L15 with a convex surface facing the object side and a biconvex lens L16, and a biconcave lens L17, the lens surfaces on both sides of which have a predetermined aspheric shape. The biconvex lens L10 corresponds to the lens LA in this invention.

[0144] The specifications of the optical system according to the second embodiment are shown below. Numerical Example 2 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 84.2242 3.2000 1.69350 53.18 0.548185 2* 24.7641 12.2180 3 54.3275 1.7000 1.88100 40.14 0.569968 4 19.2421 14.3104 5 -46.8729 1.2500 1.41390 100.82 0.533605 6 51.8469 0.2858 7 39.4670 3.5474 1.86966 20.02 0.643332 8 102.9982 (d8) 9 56.3987 0.8000 2.00069 25.46 0.613492 10 21.2660 5.0673 1.73037 32.23 0.589819 11 -78.1393 (d11) 12* -38.1015 1.1054 1.85135 40.10 0.569406 13* -336.5447 0.1500 14 40.1135 0.9000 1.92286 20.88 0.638840 15 24.4027 6.0529 1.71736 29.50 0.603381 16 -132.0011 (d16) 17(Aperture) ∞ 1.2400 18 39.9349 5.4590 1.41390 100.82 0.533605 19 -61.8782 0.1500 20 28.0224 0.9000 1.77047 29.74 0.594996 21 16.3856 8.6036 1.55032 75.50 0.539881 22 -111.2533 2.4420 23 -52.8314 0.9000 1.95375 32.32 0.590002 24 18.5517 4.9231 1.92286 20.88 0.638840 25 128.8227 0.1500 26 23.6476 0.9000 1.90043 37.37 0.576542 27 15.1999 9.9268 1.49700 81.61 0.538747 28 -33.5096 0.1500 29* -300.0000 1.3000 1.80610 40.73 0.569264 30* 53.0620 (BF) Image plane ∞ [Aspheric data] Side 1 Side 2 Side 12 Side 13 K 0.00000 -0.59024 0.00000 0.00000 A4 3.14115E-05 3.57246E-05 5.87260E-07 1.33089E-06 A6 -9.30287E-08 -2.21252E-08 9.54963E-08 8.27963E-08 A8 1.78995E-10 -4.09995E-10 -1.05725E-09 -9.67519E-10 A10 -2.19064E-13 1.97208E-12 5.82638E-12 5.47255E-12 A12 1.65913E-16 -4.24159E-15 -1.13951E-14 -1.13990E-14 A14 -7.04547E-20 4.49697E-18 0.00000E+00 0.00000E+00 A16 1.29362E-23 -1.89109E-21 0.00000E+00 0.00000E+00 29th page 30th page K 0.00000 0.00000 A4 -1.36584E-05 1.32575E-05 A6 -4.65492E-07 -4.66888E-07 A8 1.25901E-08 1.24064E-08 A10 -1.70606E-10 -1.63327E-10 A12 1.26500E-12 1.16770E-12 A14 -4.79106E-15 -4.29296E-15 A16 7.22467E-18 6.28893E-18 [Various data] Zoom ratio 1.87 Wide Angle Mid-Telephoto Focal length 12.40 17.00 23.15 F-number 2.92 2.92 2.92 Full angle of view 2ω 122.82 103.12 84.4 Image height Y 21.63 21.63 21.63 Lens length 148.00 142.30 141.41 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d8 19.9537 9.4612 3.1500 d11 6.5022 9.0635 7.8411 d16 11.4721 5.1519 1.4000 BF 22.4402 30.9877 41.3850 [Lens group data] Group starting plane focal length G1 1 -16.16 G2 9 70.11 G3 12 1503.78 G4 17 43.21 EXAMPLES

[0145] FIG. 15 is a lens configuration diagram of an optical system according to a third embodiment of the present invention.

[0146] The optical system of the third embodiment is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power.

[0147] The first lens group G1 corresponds to the object-side lens group GF in claims 1 to 6 and the lens group GFA including the lens LA in claim 7, and the composite group of the second lens group G2 to the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 1 to 6.

[0148] The composite group of the first lens group G1 to the third lens group G3 corresponds to the object-side lens group GF in claims 10 to 14, the first lens group G1 corresponds to the lens group GFA including the lens LA in claim 15, and the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 10 to 14, respectively.

[0149] An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4.

[0150] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a convex surface facing the object side, and a cemented lens consisting of a biconvex lens L4 and a biconcave lens L5, and the lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspheric shape. The biconcave lens L5 corresponds to the lens LA in this invention.

[0151] The second lens group G2 is composed only of a cemented lens made up of a negative meniscus lens L6 with a convex surface facing the object side and a positive meniscus lens L7 with a convex surface facing the object side. The second lens group G2 moves toward the image surface during focusing from an infinity object distance to a close distance.

[0152] The third lens group G3 is composed of, from the object side, a cemented lens made of a biconvex lens L8 and a negative meniscus lens L9 with its convex surface facing the image side, and a cemented lens made of a biconcave lens L10 and a biconvex lens L11.

[0153] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L12, a cemented lens consisting of a negative meniscus lens L13 with a convex surface facing the object side and a biconvex lens L14, a cemented lens consisting of a biconcave lens L15 and a biconvex lens L16, a negative meniscus lens L17 with a convex surface facing the object side, and a negative meniscus lens L18 with a convex surface facing the image side, and the lens surfaces on both sides of the negative meniscus lens L18 have a predetermined aspheric shape. The biconvex lens L12 corresponds to the lens LA in this invention.

[0154] The specifications of the optical system according to the third embodiment are shown below. Numerical Example 3 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 557.0263 3.2000 1.69350 53.18 0.548185 2 23.1636 8.4495 3 40.4452 1.7000 1.59282 68.62 0.544009 4 20.6555 8.6089 5* 43.0482 1.8800 1.59201 67.02 0.535765 6* 18.9983 1.8639 7 27.1416 8.9531 1.85451 25.15 0.610160 8 -749.3128 2.9989 1.41390 100.82 0.533605 9 19.3594 (d9) 10 33.4363 0.7000 2.00069 25.46 0.613492 11 16.7938 4.8268 1.75211 25.05 0.619087 12 87.8644 (d12) 13 31.9306 5.7987 1.90043 37.37 0.576542 14 -34.7272 0.8000 1.92286 20.88 0.638840 15 -55.6678 0.6525 16 -110.7050 0.8000 2.00100 29.13 0.599373 17 16.4803 5.5833 1.59349 67.00 0.536541 18 -152.6016 2.1784 19(Aperture) ∞ 2.0527 20 22.4831 5.4394 1.41390 100.82 0.533605 21 -48.0693 0.1511 22 42.2433 0.8000 1.88300 40.80 0.565434 23 13.5353 6.9022 1.55032 75.50 0.539881 24 -63.8490 1.3077 25 -27.4669 0.8000 1.73037 32.23 0.589819 26 24.7307 7.2312 1.92286 20.88 0.638840 27 -35.8817 0.1500 28 41.0230 0.8000 1.85451 25.15 0.610160 29 28.1086 4.4917 30* -54.3848 1.3000 1.69350 53.20 0.546484 31* -106.5247 (BF) Image plane∞ [Aspherical surface] 1 side, 5 sides, 6 sides, 30 sides K 0.00000 0.00000 0.00000 0.00000 A3 0.00000E+00 -1.65156E-05 -2.04166E-05 0.00000E+00 A4 1.30938E-05 1.53574E-06 -5.39138E-06 -1.78785E-05 A5 0.00000E+00 -1.68596E-05 -1.65584E-05 0.00000E+00 A6 -1.98839E-08 2.19398E-06 2.01360E-06 2.78978E-07 A7 0.00000E+00 -7.59058E-08 -4.09560E-08 0.00000E+00 A8 2.41619E-11 -1.94496E-09 -5.42316E-09 -8.51812E-09 A9 0.00000E+00 8.67238E-11 2.16135E-10 0.00000E+00 A10 -1.82623E-14 5.05299E-12 7.74806E-12 7.90301E-11 A11 0.00000E+00 -5.93823E-14 -4.60896E-13 0.00000E+00 A12 7.84092E-18 -1.38773E-14 -1.86374E-14 -2.84505E-13 A13 0.00000E+00 3.11908E-16 9.51558E-16 0.00000E+00 A14 -1.48833E-21 5.51021E-18 1.13424E-16 1.96430E-16 A15 0.00000E+00 9.06185E-20 -7.86519E-18 0.00000E+00 A16 1.08206E-26 -9.87459E-21 1.18780E-19 6.46300E-19 Page 31 K 0.00000 A3 0.00000E+00 A4 1.60382E-05 A5 0.00000E+00 A6 7.86467E-08 A7 0.00000E+00 A8 -3.28905E-09 A9 0.00000E+00 A10 2.08144E-11 A11 0.00000E+00 A12 4.01215E-14 A13 0.00000E+00 A14 -6.81380E-16 A15 0.00000E+00 A16 1.52268E-18 [Various data] INF 245mm Focal length 14.47 13.88 F-number 2.07 2.07 Full angle of view 2ω 114.30 114.11 Image height Y 21.63 21.63 Lens total length 128.00 128.00 [Variable interval data] INF 245mm d0∞117.0000 d9 9.9046 14.0404 d11 7.6755 3.5397 BF 20.0000 20.0000 [Lens group data] Group starting plane focal length G1 1 -16.90 G2 10 139.44 G3 13 60.46 G4 20 40.88 EXAMPLES

[0155] FIG. 20 is a lens configuration diagram of an optical system according to a fourth embodiment of the present invention.

[0156] The optical system of the fourth embodiment is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and a fourth lens group G4 with positive refractive power.

[0157] The first lens group G1 corresponds to the object-side lens group GF in claims 1 to 6 and the lens group GFA including the lens LA in claim 7, and the composite group of the second lens group G2 to the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 1 to 6.

[0158] The composite group of the first lens group G1 to the third lens group G3 corresponds to the object-side lens group GF in claims 10 to 14, the first lens group G1 corresponds to the lens group GFA including the lens LA in claim 15, and the fourth lens group G4 corresponds to the image-plane-side lens group GR in claims 10 to 14, respectively.

[0159] An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4.

[0160] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a negative meniscus lens L2 with a convex surface facing the object side, a negative meniscus lens L3 with a convex surface facing the object side, and a cemented lens consisting of a biconvex lens L4 and a biconcave lens L5, and the lens surface on the object side of the negative meniscus lens L1 and the lens surfaces on both sides of the negative meniscus lens L3 have a predetermined aspheric shape. The biconcave lens L5 corresponds to the lens LA in this invention.

[0161] The second lens group G2 is composed only of a cemented lens made up of a negative meniscus lens L6 with a convex surface facing the object side and a positive meniscus lens L7 with a convex surface facing the object side. The second lens group G2 moves toward the image surface during focusing from an infinity object distance to a close distance.

[0162] The third lens group G3 is composed of, in order from the object side, a cemented lens consisting of a biconvex lens L8 and a negative meniscus lens L9 with its convex surface facing the image side, and a cemented lens consisting of a biconcave lens L10 and a positive meniscus lens L11 with its convex surface facing the object side.

[0163] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens L12, a cemented lens consisting of a negative meniscus lens L13 with a convex surface facing the object side and a biconvex lens L14, a cemented lens consisting of a biconcave lens L15 and a biconvex lens L16, a negative meniscus lens L17 with a convex surface facing the object side, and a negative meniscus lens L18 with a convex surface facing the image side, and the lens surfaces on both sides of the negative meniscus lens L18 have a predetermined aspheric shape. The biconvex lens L12 corresponds to the lens LA in this invention.

[0164] The specifications of the optical system according to the fourth embodiment are shown below. Numerical Example 4 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 345.5736 3.2000 1.69350 53.18 0.548185 2 23.2818 8.9032 3 43.3044 1.7000 1.59282 68.62 0.544009 4 20.2688 8.6138 5* 46.6429 1.8800 1.59201 67.02 0.535765 6* 18.2799 2.2099 7 26.6989 9.1000 1.85451 25.15 0.610160 8 -193.5728 3.0000 1.42537 97.75 0.534212 9 18.8420 (d9) 10 31.1125 0.7000 2.00069 25.46 0.613492 11 16.8217 4.6143 1.68430 26.81 0.623031 12 121.3655 (d12) 13 32.2912 5.9158 1.91082 35.25 0.582104 14 -30.5864 0.8000 1.92286 20.88 0.638840 15 -55.8697 0.1500 16 -252.3463 0.8000 2.00100 29.13 0.599373 17 15.3145 5.3640 1.59349 67.00 0.536541 18 556.5564 2.5846 19(Aperture) ∞ 2.3551 20 21.5784 5.4219 1.42537 97.75 0.534212 21 -48.3957 0.1500 22 41.6151 0.8000 1.88300 40.80 0.565434 23 13.0308 7.2226 1.55032 75.50 0.539881 24 -53.9843 1.1910 25 -27.1893 0.8000 1.73037 32.23 0.589819 26 24.3547 7.4144 1.92286 20.88 0.638840 27 -34.4511 0.1500 28 49.2619 0.8000 1.85451 25.15 0.610160 29 30.3051 4.2228 30* -61.9600 1.3000 1.69350 53.20 0.546484 31* -140.0670 (BF) Image plane ∞ [Aspheric data] 1 page 5 pages 6 pages 30 pages K 0.00000 0.00000 0.00000 0.00000 A3 0.00000E+00 -4.29394E-05 -4.47699E-05 0.00000E+00 A4 1.31973E-05 -3.23917E-06 -1.07631E-05 -1.48304E-05 A5 0.00000E+00 -1.55812E-05 -1.52773E-05 0.00000E+00 A6 -2.12142E-08 2.25385E-06 1.97098E-06 -2.75773E-08 A7 0.00000E+00 -8.26148E-08 -3.01272E-08 0.00000E+00 A8 2.59364E-11 -1.88418E-09 -6.18964E-09 -2.48320E-09 A9 0.00000E+00 8.03602E-11 1.88741E-10 0.00000E+00 A10 -2.02754E-14 4.75377E-12 7.60157E-12 -1.06682E-11 A11 0.00000E+00 -4.51040E-14 -3.91478E-13 0.00000E+00 A12 1.09327E-17 -1.25773E-14 -1.49127E-14 5.33561E-13 A13 0.00000E+00 3.82153E-16 1.10177E-15 0.00000E+00 A14 -4.19867E-21 5.71539E-18 1.14822E-16 -3.53995E-15 A15 0.00000E+00 -1.55740E-19 -8.29782E-18 0.00000E+00 A16 8.60486E-25 -8.89043E-21 9.21510E-20 7.21968E-18 Page 31 K 0.00000 A3 0.00000E+00 A4 2.28967E-05 A5 0.00000E+00 A6 -1.93440E-07 A7 0.00000E+00 A8 5.22259E-10 A9 0.00000E+00 A10 -2.27781E-11 A11 0.00000E+00 A12 3.91172E-13 A13 0.00000E+00 A14 -2.16287E-15 A15 0.00000E+00 A16 3.92770E-18 [Various data] INF 230mm Focal length 14.00 13.39 F-number 2.07 2.07 Full angle of view 2ω 116.02 115.92 Image height Y 21.63 21.63 Lens total length 128.00 128.00 [Variable interval data] INF 245mm d0∞102.0000 d9 9.1032 12.8682 d11 7.5336 3.7685 BF 20.0000 20.0000 [Lens group data] Group starting plane focal length G1 1 -16.09 G2 10 121.93 G3 13 67.06 G4 20 38.19 EXAMPLES

[0165] 25 is a lens arrangement diagram at infinity at the wide-angle end of a variable magnification optical system according to Example 5. Example 5 is an example of a variable magnification optical system according to the present invention.

[0166] The variable magnification optical system of Example 5 is composed of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having negative refractive power. An aperture stop S is disposed between the fifth lens group G5 and the sixth lens group G6.

[0167] The first lens group G1 corresponds to the object-side lens group GF in claim 18, and the composite group of the second lens group G2 to the eighth lens group G8 corresponds to the image-plane-side lens group GR in claim 18, respectively.

[0168] The composite group of the first lens group G1 to the fifth lens group G5 corresponds to the object side lens group GF in claim 25, and the composite group of the sixth lens group G6 to the eighth lens group G8 corresponds to the image surface side lens group GR in claim 25, respectively.

[0169] When changing magnification from the wide-angle end to the telephoto end, the third lens group G3 and the eighth lens group G8 are fixed with respect to the image plane, the first lens group G1 moves toward the object side, the second lens group G2 moves toward the image side, the fourth lens group G4 to the seventh lens group G7 each move toward the object side, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, the distance between the fifth lens group G5 and the sixth lens group G6 increases, the distance between the sixth lens group and the seventh lens group G7 decreases, and the distance between the seventh lens group G7 and the eighth lens group G8 increases.

[0170] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, a positive meniscus lens L2 with a convex surface facing the object side, and a positive meniscus lens L3 with a convex surface facing the object side. The positive meniscus lens L3 corresponds to the lens LA in this invention.

[0171] The second lens group G2 is composed solely of a cemented lens that is made up of, in order from the object side, a biconvex lens L4 and a biconcave lens L5.

[0172] The third lens group G3 is composed of, in order from the object side, a biconvex lens L6, a cemented lens made of a biconcave lens L7 and a positive meniscus lens L8 with its convex surface facing the object side, a biconcave lens L9, and a cemented lens made of a biconcave lens L10 and a biconvex lens L11. In addition, the biconcave lens L9 and the cemented lens made of the biconcave lens L10 and the biconvex lens L11 in the third lens group G3 can be moved as a unit in a direction perpendicular to the optical axis to function as an image stabilizing group.

[0173] The fourth lens group G4 is composed of a cemented lens including, in order from the object side, a biconvex lens L12, a biconvex lens L13, and a negative meniscus lens L14 with its convex surface facing the image side.

[0174] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15, and a cemented lens made up of a negative meniscus lens L16 with its convex surface facing the object side, and a biconvex lens L17.

[0175] The sixth lens group G6 is composed only of a cemented lens having, in order from the object side, a biconvex lens L18 and a negative meniscus lens L19 with its convex surface facing the image side. The sixth lens group G6 moves as a whole toward the object side during focusing from an infinity object distance to a close distance.

[0176] The seventh lens group G7 is composed of, in order from the object side, a cemented lens made of a positive meniscus lens L20 with a convex surface facing the image side and a biconcave lens L21, and a cemented lens made of a positive meniscus lens L22 with a convex surface facing the image side and a negative meniscus lens L23 with a convex surface facing the image side. The negative meniscus lens L23 corresponds to the lens LA in this invention.

[0177] The eighth lens group G8 is composed of, in order from the object side, a cemented lens made up of a biconvex lens L24 and a biconcave lens L25, and a negative meniscus lens L26 with its convex surface facing the image side.

[0178] The specifications of the optical system according to the fifth embodiment are shown below. Numerical Example 5 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1 229.5367 2.9999 1.61340 44.27 0.563261 2 113.6783 0.3042 3 113.6776 9.7491 1.49700 81.61 0.538747 4 1554.0767 0.4000 5 155.4355 7.6390 1.41390 100.82 0.533605 6 2378.2886 (d6) 7 149.1765 5.4165 1.80518 25.46 0.615570 8 -243.4151 1.4497 1.92286 20.88 0.638840 9 615.6485 (d9) 10 103.0359 3.9954 1.53172 48.84 0.562956 11 -2868.5651 8.6239 12 -576.2228 1.0000 1.95375 32.32 0.590421 13 49.3785 3.3171 1.80809 22.76 0.628525 14 110.3663 5.8425 15 -1447.6315 0.8985 1.78590 44.20 0.563036 16 69.9168 3.4207 17 -53.3084 0.8976 1.76385 48.49 0.558845 18 70.2262 3.5785 1.85451 25.15 0.610160 19 -508.3408 (d19) 20 173.4815 2.8197 1.76385 48.49 0.558845 21 -121.8628 0.3000 22 44.0638 6.5847 1.41390 100.82 0.533605 23 -53.5108 0.8996 1.91082 35.25 0.582104 24 -566.9645 (d24) 25 69.1711 3.8855 1.72825 28.32 0.607404 26 -115.6877 0.3000 27 434.2774 0.8997 28 29.0131 5.2716 1.91082 35.25 0.582104 29 -794.7897 3.0000 1.41390 100.82 0.533605 30(Aperture) ∞ (d30) 31 60.0072 4.5217 1.74077 27.76 0.607621 32 -49.5858 0.8000 1.94595 17.98 0.654432 33 -186.1592 (d33) 34 -250.7606 1.7524 1.82166 24.04 0.623642 35 -58.2923 0.8998 1.90525 35.04 0.584723 36 52.8406 9.4298 37 -281.2955 6.0996 1.61340 44.27 0.563261 38 -25.9751 0.9999 1.41390 100.82 0.533605 39 -305.6963 (d39) 40 55.5004 7.9523 1.61340 44.27 0.563261 41 -32.0309 0.9998 1.53775 74.70 0.539232 42 148.3945 13.9898 43 -42.9000 0.8999 1.95375 32.32 0.590421 44 -258.7263 37.0956 45 ∞ 2.5000 1.51680 64.20 0.534177 46∞(BF) Image plane ∞ [Various data] Zoom ratio 3.74 Wide Angle Mid-Telephoto Focal length 154.50 280.00 577.80 F-number 5.16 5.80 6.49 Full angle of view 2ω 15.68 8.65 4.18 Image height Y 21.63 21.63 21.63 Lens total length 280.00 333.16 380.00 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d6 17.0583 74.2825 131.3315 d9 16.2732 12.2077 2.0000 d19 33.7924 21.0378 2.0000 d24 11.4042 4.8495 2.1386 d30 16.2626 26.5499 44.8691 d33 10.7755 9.2044 3.3000 d39 2.0000 12.5930 21.9269 BF 1.0000 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 263.4314 G2 7 289.6265 G3 10 -34.6015 G4 20 76.7664 G5 25 367.2863 G6 31 75.5253 G7 34 -78.2659 G8 40 -203.8433 EXAMPLES

[0179] 32 is a lens arrangement diagram at infinity of the optical system of Example 6. Example 6 is an embodiment of an optical system according to the present invention that does not vary magnification.

[0180] The optical system of the sixth embodiment is composed of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a negative refractive power. An aperture stop S is disposed between the second lens group G2 and the third lens group G3.

[0181] The composite group of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF in claims 18 and 25, and the third lens group G3 corresponds to the image-plane-side lens group GR in claims 18 and 25, respectively.

[0182] The first lens group G1 is composed of, in order from the object side, a biconvex lens L1, a positive meniscus lens L2 with a convex surface facing the object side, a biconcave lens L3, and a cemented lens made up of a negative meniscus lens L4 with a convex surface facing the object side and a positive meniscus lens L5 with a convex surface facing the object side. The biconvex lens L1 and the positive meniscus lens L2 correspond to the lens LA in this invention.

[0183] The second lens group G2 is composed only of a cemented lens made up of a negative meniscus lens L6 with a convex surface facing the object side and a positive meniscus lens L7 with a convex surface facing the object side. The second lens group G2 moves as a whole toward the image plane during focusing from an infinity object distance to a close distance.

[0184] The third lens group G3 is composed of a cemented lens consisting of a biconvex lens L8 and a biconcave lens L9, a cemented lens consisting of a biconvex lens L10 and a biconcave lens L11, a cemented lens consisting of a biconcave lens L12, a cemented lens consisting of a biconvex lens L13 and a negative meniscus lens L14 with a convex surface facing the image side, a cemented lens consisting of a negative meniscus lens L15 with a convex surface facing the object side and a biconvex lens L16, and a negative meniscus lens L17 with a convex surface facing the image side. The negative meniscus lens L15 corresponds to the lens LA in the present invention. In addition, the cemented lens consisting of the biconvex lens L10 and the biconcave lens L11 and the biconcave lens L12 in the third lens group G3 can be moved together in a direction perpendicular to the optical axis to function as a vibration isolating group.

[0185] The specifications of the optical system according to the sixth embodiment are shown below. Numerical Example 6 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1 153.4863 22.0000 1.42537 97.75 0.534212 2 -789.8781 18.5397 3 128.1087 16.6088 1.41390 100.82 0.533605 4 1068.1574 3.4364 5 -1078.9331 4.5000 1.65160 58.54 0.538879 6 402.3975 42.5469 7 84.3943 2.5000 1.88300 40.80 0.565434 8 54.8662 0.1500 9 54.2574 17.6556 1.43700 95.10 0.533516 10 341.7838 (d10) 11 379.2478 2.0000 1.88100 40.14 0.569968 12 96.1649 4.3878 1.92286 20.88 0.638840 13 125.4389 (d13) 14(Aperture) ∞ 3.0000 15 47.1304 7.6236 1.95375 32.32 0.590421 16 -136.1010 0.9500 1.84666 23.78 0.619078 17 42.9084 6.2385 18 152.3712 5.0488 1.85451 25.15 0.610160 19 -73.8150 0.9500 1.76385 48.49 0.558845 20 58.7382 3.4228 21 -138.9520 0.9500 1.69680 55.46 0.542469 22 70.9139 3.0000 23 74.4387 8.7925 1.68893 31.16 0.598858 24 -34.5131 0.9500 1.95375 32.32 0.590421 25 -181.5318 12.3412 26 85.6865 1.1000 1.41390 100.82 0.533605 27 34.6404 13.2138 1.48749 70.44 0.530491 28 -64.2408 14.0691 29 -40.8218 1.0001 1.95375 32.32 0.590421 30 -66.9955 42.4101 31 ∞ 2.4000 1.51680 64.17 0.534826 32∞(BF) Image plane ∞ [Various data] INF 2675mm Focal length 388.00 287.57 F-number 2.88 2.92 Full angle of view 2ω 6.32 4.62 Image height Y 21.63 21.63 Lens total length 330.00 330.00 [Variable interval data] INF 2675mm d0∞2345.0001 d10 3.7975 31.5887 d13 63.4170 35.6257 BF 1.0000 1.0000 [Lens group data] Group starting plane focal length G1 1 199.08 G2 11 -220.49 G3 14 -470.94 EXAMPLES

[0186] 37 is a lens arrangement diagram at infinity of the optical system of Example 7. Example 7 is an embodiment of an optical system according to the present invention that does not vary magnification.

[0187] The optical system of the seventh embodiment is composed of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. An aperture stop S is disposed between the first lens group G1 and the second lens group G2.

[0188] The composite lens group consisting of the first lens group G1 and the second lens group G2 corresponds to the object-side lens group GF in claim 18, and the third lens group G3 corresponds to the image-plane-side lens group GR in claim 18, respectively.

[0189] The first lens group G1 corresponds to the object-side lens group GF in claim 25, and the composite group of the second lens group G2 and the third lens group G3 corresponds to the image-plane-side lens group GR in claim 25, respectively.

[0190] The first lens group G1 is composed of, in order from the object side, a positive meniscus lens L1 with a convex surface facing the object side, a positive meniscus lens L2 with a convex surface facing the object side, a positive meniscus lens L3 with a convex surface facing the object side, a cemented lens made up of a positive meniscus lens L4 with a convex surface facing the object side and a negative meniscus lens L5 with a convex surface facing the object side, and a positive meniscus lens L6 with a convex surface facing the object side. The positive meniscus lens L2 corresponds to the lens LA in this invention.

[0191] The second lens group G2 is composed only of a negative meniscus lens L7 with a convex surface facing the object side. The second lens group G2 moves as a whole toward the image surface side during focusing from an infinity object distance to a close distance.

[0192] The third lens group G3 is composed of a cemented lens consisting of a negative meniscus lens L8 with a convex surface facing the object side and a biconvex lens L9, a cemented lens consisting of a biconcave lens L10 and a biconvex lens L11, a biconvex lens L12, a biconcave lens L13, and a negative meniscus lens L14 with a convex surface facing the image side, and the lens surfaces on both sides of the negative meniscus lens L14 with a convex surface facing the image side have a predetermined aspheric shape. The biconcave lens L13 corresponds to the lens LA in this invention.

[0193] The specifications of the optical system according to the seventh embodiment are shown below. Numerical Example 7 Unit: mm [Face data] Surface number rd nd vd θgF Object surface ∞ (d0) 1 72.6808 5.0242 1.94595 17.98 0.654432 2 104.0955 0.7000 3 72.1022 7.9180 1.41390 100.82 0.533605 4 217.7112 0.1500 5 54.3986 7.8515 1.59282 68.62 0.544009 6 118.8800 0.7000 7 42.8489 9.9642 1.55032 75.50 0.539881 8 218.4736 1.4000 1.85478 24.80 0.612166 9 28.4179 3.9004 10 39.3462 6.0649 1.59282 68.62 0.544009 11 127.4290 5.4355 12 (Aperture) ∞ (d12) 13 657.7179 1.0000 1.51742 52.15 0.558829 14 28.1131 (d14) 15 287.8934 0.9000 1.85451 25.15 0.610160 16 25.1931 5.5789 1.59282 68.62 0.544009 17 -106.2671 2.5244 18 -44.0902 0.9500 1.55032 75.50 0.539881 19 92.5544 3.7150 1.68430 26.81 0.623031 20 -89.6313 0.1500 21 96.6146 5.8235 1.78880 28.43 0.600773 22 -42.0630 0.1500 23 -75.0235 1.0000 1.41390 100.82 0.533605 24 89.0720 3.6009 25* -90.9091 1.7000 1.51633 64.06 0.533322 26* -200.0000 (BF) Image plane ∞ [Aspheric data] 25th page 26th page K 0.00000 0.00000 A4 2.23113E-06 3.95648E-06 A6 -2.52151E-08 -2.40968E-08 A8 9.33417E-11 6.86747E-11 A10 -1.19404E-13 -5.63942E-14 A12 3.13559E-17 -3.57179E-17 A14 0.00000E+00 0.00000E+00 [Various data] INF 800mm Focal length 131.00 111.39 F-number 1.85 2.10 Full angle of view 2ω 18.04 15.44 Image height Y 21.63 21.63 Lens length 129.50 129.50 [Variable interval data] INF 800mm d0∞670.5000 d12 3.9792 17.1120 d14 18.8972 5.7644 BF 30.4221 30.4221 [Lens group data] Group starting plane focal length G1 1 78.79 G2 13 -56.79 G3 15 101.15

[0194] Values ​​corresponding to the conditional expressions in each embodiment are shown below. [Conditional expression corresponding value] Conditional Expression Example 1 Example 2 Example 3 Example 4 (1) VD_A > 96.00 100.82 100.82 100.82 97.75 (2) ΔθgF_A > 0.057 0.067 0.067 0.067 0.062 Conditional Expression Example 5 Example 6 Example 7 (1) VD_A > 96.00 100.82 97.75~100.82 100.82 (2) ΔθgF_A > 0.057 0.067 0.062~0.067 0.067 (3) DAF / f > 0.270 0.346 0.372~0.463 0.271 (4) DAR / f > 0.120 0.124 0.137 0.333 (5) 0.40 > DFR / LT > 0.10 0.3456 0.1922 0.1459 (6) 0.70 > HS / HR1 > 0.20 0.2831 0.3158 0.5084 [Explanation of symbols]

[0195] S: Aperture I: image plane G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: 6th lens group G7: Seventh lens group G8: 8th lens group GF: Object-side lens group GR: Imaging lens group CC line (wavelength λ=656.3nm) dd line (wavelength λ=587.6nm) gg line (wavelength λ=435.8nm) Y image height ΔS Sagittal image plane ΔM meridional image plane

Claims

1. the optical system is configured by arranging, in order from the object side, an object-side lens group GF and an image-side lens group GR, the object-side lens group GF having a negative refractive power as a whole, the image-side lens group GR having a positive refractive power as a whole, An optical system comprising a lens LA, which satisfies the following conditional expression (1), in at least one of the object-side lens group GF and the image-plane-side lens group GR: (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

2. 2. The optical system according to claim 1, The optical system is characterized in that the lens LA satisfies the following conditional expression (2): (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

3. 2. The optical system according to claim 1, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. The optical system is characterized in that the lens LA is disposed in the object-side lens group GF and has negative refractive power.

4. 2. The optical system according to claim 1, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. The optical system is characterized in that the lens LA is disposed in the image-side lens group GR and has positive refractive power.

5. 2. The optical system according to claim 1, when the optical system has a variable magnification, in a state where the optical system is in a widest angle state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is in a focused on infinity, among the air spaces between adjacent lenses in the optical system, a lens group space between the object side lens group GF and the image side lens group GR is maximum; The optical system is characterized in that the lens LA is disposed in the object-side lens group GF and has negative refractive power.

6. 2. The optical system according to claim 1, when the optical system has a variable magnification, in a state where the optical system is in a widest angle state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is in a focused on infinity, among the air spaces between adjacent lenses in the optical system, a lens group space between the object side lens group GF and the image side lens group GR is maximum; The optical system is characterized in that the lens LA is disposed in the image-side lens group GR and has positive refractive power.

7. 2. The optical system according to claim 1, a lens group GFA including the lens LA and having negative refractive power; In the case where the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces which change during the magnification change as boundaries, the lens group GFA is disposed closest to the image surface of the object-side lens group GF, or the lens group GFA is identical to the object-side lens group GF, When the optical system does not change magnification, the lens group GFA is the same as the object-side lens group GF, The optical system is characterized in that the lens group GFA is composed of four or more lenses.

8. In the optical system according to any one of claims 1 to 7, an aspheric surface having a positive refractive power that is stronger or a negative refractive power that is weaker at the periphery of an effective light beam diameter relative to the optical axis center;

9. In the optical system according to any one of claims 1 to 7, An optical system characterized in that the image-side lens group GR has an aspheric surface whose positive refractive power becomes weaker or whose negative refractive power becomes stronger at the periphery of an effective light beam diameter with respect to the optical axis center.

10. the optical system is configured by arranging, in order from the object side, an object side lens group GF and an image side lens group GR, an aperture stop is arranged between the object side lens group GF and the image side lens group GR, the object side lens group GF has a positive or negative refractive power as a whole, and the image side lens group GR has a positive refractive power as a whole, An optical system comprising a lens LA, which satisfies the following conditional expression (1), in at least one of the object-side lens group GF and the image-plane-side lens group GR: (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

11. 11. The optical system according to claim 10, The optical system is characterized in that the lens LA satisfies the following conditional expression (2): (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

12. 11. The optical system according to claim 10, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. The optical system is characterized in that the lens LA is disposed in the object-side lens group GF and has negative refractive power.

13. 11. The optical system according to claim 10, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. The optical system is characterized in that the lens LA is disposed in the image-side lens group GR and has positive refractive power.

14. 11. The optical system according to claim 10, When the optical system has a variable magnification, in a state where the optical system is in a widest angle state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is in a focused on infinity, a height from the optical axis of an on-axis marginal ray passing through the aperture stop is higher than a height from the optical axis of an on-axis marginal ray passing through an optical surface closest to the object of the optical system.

15. 11. The optical system according to claim 10, a lens group GFA including the lens LA and having negative refractive power; When the optical system varies its magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces that change during the magnification change as boundaries, the lens group GFA is disposed closest to the object among the lens groups having negative refractive power included in the object-side lens group GF, In the case where the optical system does not change magnification, when the object-side lens group GF is divided into lens groups using all of the air spaces that change during focusing as boundaries, the lens group GFA is disposed closest to the object among the lens groups having negative refractive power included in the object-side lens group GF, The optical system is characterized in that the lens group GFA is composed of four or more lenses.

16. In the optical system according to any one of claims 10 to 15, an aspheric surface having a positive refractive power that is stronger or a negative refractive power that is weaker at the periphery of an effective light beam diameter relative to the optical axis center;

17. In the optical system according to any one of claims 10 to 15, An optical system characterized in that the image-side lens group GR has an aspheric surface whose positive refractive power becomes weaker or whose negative refractive power becomes stronger at the periphery of an effective light beam diameter with respect to the optical axis center.

18. An optical system including, in order from the object side, an object-side lens group GF having positive refractive power and an image-plane-side lens group GR, an aperture stop, and a lens LA that satisfies the following conditional expression (1): (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

19. 19. The optical system according to claim 18, The optical system is characterized in that the lens LA satisfies the following conditional expression (2): (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

20. 20. The optical system according to claim 18 or 19, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. the lens LA is disposed in the object-side lens group GF and has positive refractive power; An optical system characterized by satisfying the following conditional expression (3): (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

21. 20. The optical system according to claim 18 or 19, When the optical system changes magnification, the distance between at least the object side lens group GF and the image side lens group GR changes during the magnification change. the lens LA is disposed in the image-side lens group GR and has negative refractive power; An optical system characterized by satisfying the following conditional expression (4): (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

22. 19. The optical system according to claim 18, when the optical system has a variable magnification, in a state where the optical system is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is in a focused on infinity, among the air spaces between adjacent lenses of the optical system, a lens group space between the object side lens group GF and the image surface side lens group GR is maximum; the lens LA is disposed in the object-side lens group GF and has positive refractive power; An optical system characterized by satisfying the following conditional expression (3): (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

23. 19. The optical system according to claim 18, when the optical system has a variable magnification, in a state where the optical system is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is in a focused on infinity, among the air spaces between adjacent lenses of the optical system, a lens group space between the object side lens group GF and the image surface side lens group GR is maximum; the lens LA is disposed in the image-side lens group GR and has negative refractive power; An optical system characterized by satisfying the following conditional expression (4): (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

24. 24. The optical system according to claim 22 or 23, An optical system characterized by satisfying the following conditional expression (5): (5) 0.40 > DFR / LT > 0.10 however, When the optical system does not change magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-side lens group GR when focused at infinity LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when the lens is focused at infinity When the optical system has a variable magnification, DFR: the air gap on the optical axis between the object-side lens group GF and the image-side lens group GR when the lens is focused at infinity in the most telephoto state LT: The distance on the optical axis between the surface closest to the object and the image plane of the optical system when the lens is in the most telephoto position and focused at infinity.

25. An optical system including, in order from the object side, an object-side lens group GF having positive refractive power and an image-side lens group GR, an aperture stop is disposed between the object-side lens group GF and the image-side lens group GR, and a lens LA that satisfies the following conditional expression (1): (1) VD_A > 96.00 however, VD_A: Abbe number of the lens LA based on the d line

26. 26. The optical system according to claim 25, The optical system is characterized in that the lens LA satisfies the following conditional expression (2): (2) ΔθgF_A > 0.057 however, ΔθgF_A: average value of deviation ΔθgF of partial dispersion ratio for the g-line of the lens LA Here, the deviation ΔθgF of the partial dispersion ratio for the g-line is expressed as follows, where θgF is the partial dispersion ratio for the g-line and VD is the Abbe number for the d-line: ΔθgF=θgF-(0.648285-0.00180123×VD) is calculated for each lens as

27. 26. The optical system according to claim 25, the lens LA is disposed in the object-side lens group GF and has positive refractive power; An optical system characterized by satisfying the following conditional expression (3): (3) DAF / f > 0.270 however, When the optical system does not change magnification, DAF: the distance on the optical axis between the image-plane side surface of the lens LA arranged in the object-side lens group GF and the aperture stop when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAF: the distance on the optical axis between the aperture stop and the image-side surface of the lens LA arranged in the object-side lens group GF when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

28. 26. The optical system according to claim 25, the lens LA is disposed in the image-side lens group GR and has negative refractive power; An optical system characterized by satisfying the following conditional expression (4): (4) DAR / f > 0.120 however, When the optical system does not change magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when focused at infinity f: focal length of the optical system when focused at infinity When the optical system has a variable magnification, DAR: the distance on the optical axis between the aperture stop and the object-side surface of the lens LA arranged in the image-side lens group GR when the lens is focused at infinity in the most telephoto state f: focal length of the optical system when focused at infinity in the most telephoto state

29. 29. The optical system according to claim 25, An optical system characterized in that, when the optical system has a variable magnification, in a state where the optical system is in a most telephoto state and focused on infinity, or when the optical system does not have a variable magnification, in a state where the optical system is focused on infinity, a height from the optical axis of an on-axis marginal ray passing through the aperture stop is lower than a height from the optical axis of an on-axis marginal ray passing through an optical surface closest to the object of the optical system.

30. 30. The optical system according to claim 29, An optical system characterized by satisfying the following conditional expression (6): (6) 0.70 > HS / HR1 > 0.20 however, When the optical system does not change magnification, HS: Height from the optical axis of the axial marginal ray passing through the aperture stop when focused at infinity HR1: Height from the optical axis of the axial marginal ray passing through the optical surface closest to the object in the optical system when focused at infinity When the optical system has a variable magnification, HS: Height from the optical axis of the axial marginal ray passing through the aperture stop when the lens is focused at infinity in the most telephoto state HR1: the height from the optical axis of the axial marginal ray passing through the optical surface closest to the object of the optical system when the optical system is in the most telephoto state and focused at infinity

Images