Imaging optical system

Abstract

To provide an image formation optical system that has a hand tremor correction mechanism incorporated, is small in a maximum aperture F value in a zoom entire area, and achieves miniaturization.SOLUTION: An image formation optical system comprises, in order from an object side,: a first lens group G1 that has positive refractive power; a front-side lens group GF that has negative refractive power; and a rear-side lens group GR that has the positive refractive power, in which when varying a magnification from a wide-angle end to a telephoto end, an interval between the first lens group G1 and the front-side lens group GF increases, an interval between the front-side lens group GF and rear-side lens group GR contracts, the first lens group G1 moves monotonously to the object side, the first lens group G1 has at least one piece of a negative lens, the front-side lens group GF is composed of one or more lens groups having the negative refractive power, the rear-side lens group GR has a final lens group GL that is disposed closest to an imaging plane side, fixed with respect to an imaging plane I, and does not move upon magnification or focusing, the final lens group GL has an antitremor lens group GS movable in a direction including a vertical direction component relative to an optical axis, and the image formation optical system satisfies a prescribed conditional expression.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging optical system suitable for a photographing lens used in a digital camera, a video camera, and the like.

Background Art

[0002] In recent years, so-called mirrorless cameras that eliminate a quick return mirror disposed between an imaging optical system and an imaging device and guide light rays to a finder optical system have become widespread.

[0003] Since the housing of a mirrorless camera is downsized by eliminating the mirror, downsizing of the imaging optical system has been required accordingly. In addition, there is a demand for a large-aperture zoom lens that is equipped with a shake correction mechanism and has a small open F value throughout the zoom range.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, a bright zoom lens of a positive lead type in which the lens group on the object side is fixed to the image plane at the time of zooming with an open F value of about 2.8 is disclosed. The zoom lens disclosed in Patent Document 1 has an advantage of high convenience and robustness because the overall optical length does not change, but has a problem that the size of the imaging optical system is large.

[0006] Patent Document 2 discloses a positive-lead type zoom lens with a bright aperture of approximately F2.8 and a shortened optical length at the wide-angle end. However, the zoom lens disclosed in Patent Document 2 has a problem in that, because many large-diameter lens groups that move during magnification are arranged on the image side of the aperture, the mechanism required for magnification becomes large, resulting in a large radial size of the lens barrel.

[0007] This invention was made in view of the above circumstances, and aims to provide an imaging optical system that incorporates an image stabilization mechanism, has a small maximum aperture (F) throughout the zoom range, and achieves miniaturization. [Means for solving the problem]

[0008] The first invention according to the present invention comprises, in order from the object side, a first lens group G1 having positive refractive power, a front lens group GF having negative refractive power, and a rear lens group GR having positive refractive power, wherein when magnification is changed from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the front lens group GF increases, the distance between the front lens group GF and the rear lens group GR decreases, the first lens group G1 moves monotonically toward the object side, the first lens group G1 has at least one negative lens, the front lens group GF consists of a lens group having 1 or more negative refractive powers, the rear lens group GR has a final lens group GL positioned closest to the image plane, fixed with respect to the image plane I, and not moving during magnification and focusing, the final lens group GL has an anti-vibration lens group GS that can move in a direction including a component perpendicular to the optical axis, and satisfies the following conditional formula. (1) 0.30 <f1 / fT<1.50 (2) 0.80 < |f1n| / f1 < 4.00 (3) 20.0 <LTT×FnoT / Ymax<50.0 however, f1: Focal length of the first lens group G1 fT: Focal length of the imaging optical system at infinity focus at the telephoto end. f1n: The focal length of at least one negative lens among the negative lenses in the first lens group G1. LTT: Total optical length of the imaging optical system at the telephoto end FnoT: The maximum aperture value of the imaging optical system when focused at infinity at the telephoto end. Ymax: Maximum image height in an imaging optical system

[0009] The second invention according to the present invention is characterized in that the front lens group GF has positive lenses, and the positive lens located closest to the object satisfies the following condition. (4) PgFFp + 0.0022 × νdFp < 0.678 however, PgFFp: The partial dispersion ratio of the g-line and F-line of the positive lens located closest to the object among the positive lenses in the front lens group GF. νdFp: The Abbe number with respect to the d line of the positive lens located closest to the object among the positive lenses in the front lens group GF.

[0010] The third invention according to the present invention is characterized in that the final lens group GL has a negative lens, and at least one of the negative lenses satisfies the following conditional expression. (5) PgFLn + 0.0021 × νdLn > 0.658 however, PgFLn: Partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses in the final lens group GL. νdLn: Abbe number with respect to the d line of at least one negative lens among the negative lenses of the final lens group GL.

[0011] The fourth invention according to the present invention is characterized in that the rear lens group GR has an object-side lens group GO that has a positive refractive power closest to the object, and has at least one focusing lens group GFcs that moves along the optical axis in focusing from an object at infinity to an object at a close distance, located closer to the image plane than the object-side lens group GO.

[0012] The fifth invention according to the present invention is characterized in that the rear lens group GR has an aperture stop S, the aperture stop S is fixed with respect to the image plane I during zooming from the wide-angle end to the telephoto end, and among the lens groups located on the image side of the aperture stop S, all the lens groups that move along the optical axis during zooming from the wide-angle end to the telephoto end are the focusing lens group GFcs that moves along the optical axis during focusing from an infinite object to a close-distance object.

[0013] The sixth invention according to the present invention is characterized by satisfying the conditional expression shown below. (6) 2.50 < f1 / |fFW| < 5.00 However, f1: The focal length of the first lens group G1 fFW: The focal length of the front lens group GF at the wide-angle end

[0014] The seventh invention according to the present invention is characterized by satisfying the conditional expression shown below. (7) L1 / LTW < 0.17 However, L1: The length on the optical axis from the most object-side lens surface to the most image-side lens surface of the first lens group G1 LTW: The overall optical length of the imaging optical system at the wide-angle end

[0015] The eighth invention according to the present invention is characterized in that among the negative lenses of the first lens group G1, at least one negative lens satisfies the conditional expression shown below. (8) νd1n < 50.0 (9) PgF1n + 0.0024 × νd1n < 0.677 However, νd1n: The Abbe number with respect to the d-line of at least one negative lens among the negative lenses of the first lens group G1 PgF1n: The partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses of the first lens group G1

[0016] The ninth invention according to the present invention is characterized by satisfying the conditional expression shown below. (10) 0.55 < |fS| / fW < 1.20 however, fS: Focal length of the GS image stabilization lens group fW: Focal length of the imaging optical system at infinity focus at the wide-angle end.

[0017] The tenth invention according to the present invention is characterized by satisfying the following conditional expression. (11) BF / Ymax < 3.00 however, BF: Back focus in imaging optical systems Ymax: Maximum image height in an imaging optical system [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an imaging optical system that incorporates an image stabilization mechanism, has a small maximum aperture (F-number) throughout the entire zoom range, and achieves miniaturization. [Brief explanation of the drawing]

[0019] [Figure 1] This is a lens configuration diagram at the wide-angle end and infinity shooting distance according to Embodiment 1 of the imaging optical system of the present invention. [Figure 2] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at the wide-angle end with an infinity shooting distance. [Figure 3] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at the wide-angle end and an imaging distance of infinity. [Figure 4] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at the wide-angle end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 5] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at the wide-angle end with a shooting distance of 2260 mm. [Figure 6] This is a lateral aberration diagram of the imaging optical system of Example 1 at the wide-angle end with a shooting distance of 2260 mm. [Figure 7] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at an intermediate zoom level and an infinity shooting distance. [Figure 8] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at an intermediate zoom level and an infinity shooting distance. [Figure 9] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at an intermediate zoom level, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 10] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at an intermediate zoom level with a shooting distance of 3588 mm. [Figure 11] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at an intermediate zoom level with a shooting distance of 3588 mm. [Figure 12] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at the telephoto end with an infinity shooting distance. [Figure 13] This is a diagram of the lateral aberration at the telephoto end of the imaging optical system of Example 1 at an infinity shooting distance. [Figure 14] This is a diagram of the lateral aberration of the imaging optical system of Example 1 at the telephoto end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 15] This is a longitudinal aberration diagram of the imaging optical system of Example 1 at the telephoto end, at a shooting distance of 5348 mm. [Figure 16] This is a lateral aberration diagram of the imaging optical system of Example 1 at the telephoto end, with a shooting distance of 5348 mm. [Figure 17] This is a lens configuration diagram at the wide-angle end and infinity shooting distance according to Embodiment 2 of the imaging optical system of the present invention. [Figure 18] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at the wide-angle end and an imaging distance of infinity. [Figure 19] This is a diagram of the lateral aberration of the imaging optical system of Example 2 at the wide-angle end and an imaging distance of infinity. [Figure 20] This is a diagram of the lateral aberration of the imaging optical system of Example 2 at the wide-angle end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 21] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at the wide-angle end with a shooting distance of 2142 mm. [Figure 22] This is a lateral aberration diagram of the imaging optical system of Example 2 at the wide-angle end with a shooting distance of 2142 mm. [Figure 23] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at an intermediate zoom level and an infinity shooting distance. [Figure 24]This is a diagram of the lateral aberration of the imaging optical system of Example 2 at an intermediate zoom level and an infinity shooting distance. [Figure 25] This is a diagram of the lateral aberration of the imaging optical system of Example 2 at an intermediate zoom level, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 26] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at an intermediate zoom level and a shooting distance of 3460 mm. [Figure 27] This is a diagram of the lateral aberration of the imaging optical system of Example 2 at an intermediate zoom level and a shooting distance of 3460 mm. [Figure 28] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at the telephoto end with an infinity shooting distance. [Figure 29] This is a diagram of the lateral aberration at the telephoto end of the imaging optical system of Example 2 at an infinity shooting distance. [Figure 30] This is a diagram of the lateral aberration of the imaging optical system of Example 2 at the telephoto end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 31] This is a longitudinal aberration diagram of the imaging optical system of Example 2 at the telephoto end, at a shooting distance of 5325 mm. [Figure 32] This is a lateral aberration diagram of the imaging optical system of Example 2 at the telephoto end, with a shooting distance of 5325 mm. [Figure 33] This is a lens configuration diagram at the wide-angle end and infinity shooting distance according to Embodiment 3 of the imaging optical system of the present invention. [Figure 34] This is a longitudinal aberration diagram of the imaging optical system of Example 3 at the wide-angle end with an infinity shooting distance. [Figure 35] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at the wide-angle end and an imaging distance of infinity. [Figure 36] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at the wide-angle end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 37] This is a longitudinal aberration diagram of the imaging optical system of Example 3 at the wide-angle end with a shooting distance of 2209 mm. [Figure 38] This is a lateral aberration diagram of the imaging optical system of Example 3 at the wide-angle end with a shooting distance of 2209 mm. [Figure 39]This is a longitudinal aberration diagram of the imaging optical system of Example 3 at an intermediate zoom level and an infinity shooting distance. [Figure 40] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at an intermediate zoom level and an infinity shooting distance. [Figure 41] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at an intermediate zoom level, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 42] This is a longitudinal aberration diagram of the imaging optical system of Example 3 at an intermediate zoom level with a shooting distance of 3524 mm. [Figure 43] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at an intermediate zoom level with a shooting distance of 3524 mm. [Figure 44] This is a longitudinal aberration diagram of the imaging optical system of Example 3 at the telephoto end with an infinity shooting distance. [Figure 45] This is a diagram of the lateral aberration at the telephoto end of the imaging optical system of Example 3 at an infinity shooting distance. [Figure 46] This is a diagram of the lateral aberration of the imaging optical system of Example 3 at the telephoto end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 47] This is a longitudinal aberration diagram of the imaging optical system of Example 3 at the telephoto end, at a shooting distance of 5583 mm. [Figure 48] This is a lateral aberration diagram of the imaging optical system of Example 3 at the telephoto end, with a shooting distance of 5583 mm. [Figure 49] This is a lens configuration diagram at the wide-angle end and infinity shooting distance according to Embodiment 4 of the imaging optical system of the present invention. [Figure 50] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at the wide-angle end with an infinity shooting distance. [Figure 51] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at the wide-angle end and an imaging distance of infinity. [Figure 52] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at the wide-angle end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 53] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at the wide-angle end with a shooting distance of 2168 mm. [Figure 54]This is a lateral aberration diagram of the imaging optical system of Example 4 at the wide-angle end with a shooting distance of 2168 mm. [Figure 55] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at an intermediate zoom level and an infinity shooting distance. [Figure 56] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at an intermediate zoom level and an infinity shooting distance. [Figure 57] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at an intermediate zoom level, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 58] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at an intermediate zoom level with a shooting distance of 3535 mm. [Figure 59] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at an intermediate zoom level with a shooting distance of 3535 mm. [Figure 60] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at the telephoto end with an infinity shooting distance. [Figure 61] This is a diagram of the lateral aberration at the telephoto end of the imaging optical system of Example 4 at an infinity shooting distance. [Figure 62] This is a diagram of the lateral aberration of the imaging optical system of Example 4 at the telephoto end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 63] This is a longitudinal aberration diagram of the imaging optical system of Example 4 at the telephoto end, with a shooting distance of 5488 mm. [Figure 64] This is a lateral aberration diagram of the imaging optical system of Example 4 at the telephoto end, with a shooting distance of 5488 mm. [Figure 65] This is a lens configuration diagram at the wide-angle end and infinity shooting distance according to Embodiment 5 of the imaging optical system of the present invention. [Figure 66] This is a longitudinal aberration diagram of the imaging optical system of Example 5 at the wide-angle end with an infinity shooting distance. [Figure 67] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at the wide-angle end and an imaging distance of infinity. [Figure 68] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at the wide-angle end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 69]This is a longitudinal aberration diagram of the imaging optical system of Example 5 at the wide-angle end with a shooting distance of 2138 mm. [Figure 70] This is a lateral aberration diagram of the imaging optical system of Example 5 at the wide-angle end with a shooting distance of 2138 mm. [Figure 71] This is a longitudinal aberration diagram of the imaging optical system of Example 5 at an intermediate zoom level and an infinity shooting distance. [Figure 72] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at an intermediate zoom level and an infinity shooting distance. [Figure 73] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at an intermediate zoom level, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 74] This is a longitudinal aberration diagram of the imaging optical system of Example 5 at an intermediate zoom level with a shooting distance of 3481 mm. [Figure 75] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at an intermediate zoom level with a shooting distance of 3481 mm. [Figure 76] This is a longitudinal aberration diagram of the imaging optical system of Example 5 at the telephoto end with an infinity shooting distance. [Figure 77] This is a diagram of the lateral aberration at the telephoto end of the imaging optical system of Example 5 at an infinity shooting distance. [Figure 78] This is a diagram of the lateral aberration of the imaging optical system of Example 5 at the telephoto end, with a shooting distance of infinity and 0.3° vibration isolation. [Figure 79] This is a longitudinal aberration diagram of the imaging optical system of Example 5 at the telephoto end, at a shooting distance of 5474 mm. [Figure 80] This is a lateral aberration diagram of the imaging optical system of Example 5 at the telephoto end, at a shooting distance of 5474 mm. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described below.

[0021] Furthermore, when the refractive indices for the g-line (wavelength 435.8 nm), F-line (wavelength 486.1 nm), d-line (wavelength 587.6 nm), and C-line (wavelength 656.3 nm) are denoted as ng, nF, nd, and nC, respectively, the Abbe number νd for the d-line and the partial dispersion ratio PgF for the g-line and F-line are expressed by the following formulas. νd=(nd-1) / (nF-nC) PgF = (ng - nF) / (nF - nC)

[0022] As can be seen from Figures 1, 17, 33, 49, and 65, the imaging optical system of the present invention consists of, in order from the object side, a first lens group G1 having positive refractive power, a front lens group GF having negative refractive power, and a rear lens group GR having 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 front lens group GF increases, and the distance between the front lens group GF and the rear lens group GR decreases, causing the first lens group G1 to move monotonically toward the object side. The first lens group G1 has at least one negative lens, the front lens group GF consists of a lens group having 1 or more negative refractive powers, the rear lens group GR is positioned closest to the image plane, is fixed to the image plane I, and has a final lens group GL that does not move during magnification and focusing, and the final lens group GL has an anti-vibration lens group GS that can move in a direction including a component perpendicular to the optical axis, and satisfies the following conditional equation. (1) 0.30 <f1 / fT<1.50 (2) 0.80 < |f1n| / f1 < 4.00 (3) 20.0 <LTT×FnoT / Ymax<50.0 however, f1: Focal length of the first lens group G1 fT: Focal length of the imaging optical system at infinity focus at the telephoto end. f1n: The focal length of at least one negative lens among the negative lenses in the first lens group G1. LTT: Total optical length of the imaging optical system at the telephoto end FnoT: The maximum aperture value of the imaging optical system when focused at infinity at the telephoto end. Ymax: Maximum image height in an imaging optical system

[0023] The imaging optical system of the present invention arranges, from the object side, a first lens group G1 with positive refractive power, a front lens group GF with negative refractive power, and a rear lens group GR with positive refractive power. At the wide-angle end, by bringing the first lens group G1 and the front lens group GF closer together, the lens group with negative combined refractive power is positioned on the object side, resulting in a retrofocus type lens arrangement overall, ensuring a good peripheral illumination ratio at the wide-angle end. Furthermore, at the telephoto end, by increasing the distance between the first lens group G1 and the front lens group GF, and decreasing the distance between the front lens group GF and the rear lens group GR, a telephoto type lens arrangement overall is achieved, shortening the overall optical length of the imaging optical system at the telephoto end and ensuring a good peripheral illumination ratio.

[0024] The imaging optical system of the present invention is configured such that, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves monotonically toward the object, and at the wide-angle end, the distance between the front lens group GF and the rear lens group GR is smaller compared to a zoom lens where the first lens group G1 is fixed during magnification as described in Patent Document 1. This achieves a larger aperture and a reduction in the overall optical length of the imaging optical system at the wide-angle end. Furthermore, by moving the first lens group G1 monotonically, magnification can be performed efficiently. In addition, by positioning the image-stabilizing lens group GS in the final lens group GL which is fixed to the image plane I, the mixing of the image stabilization mechanism, magnification mechanism, and focusing mechanism is avoided, and the incorporation of an image stabilization mechanism and miniaturization of the lens barrel are achieved simultaneously.

[0025] Conditional equation (1) defines the ratio of the focal length of the first lens group G1 to the focal length of the imaging optical system at infinity focus at the telephoto end. By satisfying conditional equation (1), the imaging optical system of the present invention achieves both miniaturization and correction of various aberrations.

[0026] If the refractive power of the first lens group G1 weakens beyond the upper limit of condition (1), the amount of movement of the first lens group G1 during magnification increases, which increases the mechanisms required for the movement of the first lens group G1 and leads to a larger lens barrel. Furthermore, if the optical length of the imaging optical system at the telephoto end increases due to the increased amount of movement of the first lens group G1 during magnification, it becomes difficult to maintain a good peripheral illumination ratio at the telephoto end. In this case, the diameter of the first lens group G1 needs to be increased to maintain a good peripheral illumination ratio, which leads to a larger imaging optical system.

[0027] When the refractive power of the first lens group G1 increases beyond the lower limit of condition (1), it becomes difficult to suppress spherical aberration and astigmatism occurring in the first lens group G1.

[0028] Furthermore, regarding condition (1), it is preferable to limit its lower limit to 0.50 or its upper limit to 1.00 to make the aforementioned effect more reliable.

[0029] Condition (2) defines the ratio between the absolute value of the focal length of at least one negative lens among the negative lenses of the first lens group G1 and the focal length of the first lens group G1. By satisfying condition (2), the imaging optical system of the present invention achieves both miniaturization and correction of various aberrations.

[0030] When the upper limit of condition (2) is exceeded and the refractive power of the negative lens included in the first lens group G1 decreases, the correction effect of various aberrations in the first lens group G1, in particular the correction effect of chromatic aberration at the telephoto end, decreases, which is undesirable.

[0031] If the refractive power of the negative lens included in the first lens group G1 exceeds the lower limit of condition (2), the refractive power of each lens constituting the first lens group G1 will increase, leading to an increase in the size of the first lens group G1, which is undesirable.

[0032] Furthermore, regarding condition (2), it is preferable to limit its lower limit to 1.30 or its upper limit to 3.30 to make the aforementioned effect more certain.

[0033] Conditional equation (3) defines the ratio of the total optical length of the imaging optical system at the telephoto end, the maximum aperture F value when the imaging optical system is focused at infinity at the telephoto end, and the maximum image height of the imaging optical system. By satisfying conditional equation (3), the imaging optical system of the present invention achieves both brightness, miniaturization, and correction of various aberrations.

[0034] Generally, the smaller the F-number of the imaging optical system, the higher the on-axis rays passing through the imaging optical system. Also, the larger the maximum image height, the higher the off-axis rays passing through the group closest to the object or the image plane. These correspond to a decrease in the FnoT / Ymax component in condition (3). To correct aberrations in such a situation, it is effective to increase the overall optical length of the imaging optical system to soften the incident rays on each lens surface of the imaging optical system. However, in order to achieve this while maintaining miniaturization, it is necessary to appropriately set the overall optical length of the imaging optical system according to the F-number and maximum image height at the telephoto end.

[0035] When the upper limit of condition (3) is exceeded, and the total optical length of the imaging optical system at the telephoto end becomes large relative to the ratio of the maximum aperture F-number at infinity focus and the maximum image height of the imaging optical system at the telephoto end, it becomes easier to suppress various aberrations occurring in the entire imaging optical system, but the total optical length of the imaging optical system increases. Alternatively, the F-number at the telephoto end becomes large, making it difficult to achieve a bright imaging optical system.

[0036] When the lower limit of condition (3) is exceeded, and the total optical length of the imaging optical system at the telephoto end becomes smaller than the ratio of the maximum aperture F value at infinity focus and the maximum image height in the imaging optical system at the telephoto end, the total optical length of the imaging optical system can be kept small. However, the refraction of light rays in the imaging optical system becomes stronger, increasing the aberrations generated in each lens group. This makes it difficult to adequately correct variations such as astigmatism, spherical aberration, and coma aberration, mainly during magnification.

[0037] Furthermore, regarding condition (3), it is preferable to limit its lower limit to 23.0 or its upper limit to 40.0 to make the aforementioned effect more certain.

[0038] Furthermore, in the imaging optical system of the present invention, it is desirable that the front lens group GF has positive lenses, and that the positive lens located closest to the object satisfies the following condition. (4) PgFFp + 0.0022 × νdFp < 0.678 however, PgFFp: The partial dispersion ratio of the g-line and F-line of the positive lens located closest to the object among the positive lenses in the front lens group GF. νdFp: The Abbe number with respect to the d line of the positive lens located closest to the object among the positive lenses in the front lens group GF.

[0039] Conditional equation (4) specifies the preferred optical properties for the material of the positive lens located closest to the object among the positive lenses in the front lens group GF, in order to effectively correct chromatic aberration.

[0040] If an optical material with high positive anomalous partial dispersion is used as the material for the positive lens located closest to the object among the positive lenses included in the front lens group GF, the lateral chromatic aberration of the g-line in the over-angle direction at the wide-angle end will increase, making it difficult to correct lateral chromatic aberration, including the second-order spectrum.

[0041] When the upper limit of condition (4) is exceeded, and the positive anomalous partial dispersion of the positive lens located closest to the object among the positive lenses included in the front lens group GF becomes large, the effect of correcting lateral chromatic aberration, including the second-order spectrum, in the front lens group GF at the wide-angle end becomes too large, making it difficult to suppress lateral chromatic aberration.

[0042] Furthermore, regarding condition (4), it is preferable to limit its upper limit to 0.675, which will make the aforementioned effect more certain.

[0043] Furthermore, in the imaging optical system of the present invention, it is desirable that the final lens group GL has negative lenses, and that at least one of these negative lenses satisfies the following conditional equation. (5) 0.658 <PgFLn+0.0021×νdLn however, PgFLn: Partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses in the final lens group GL. νdLn: Abbe number with respect to the d line of at least one negative lens among the negative lenses of the final lens group GL.

[0044] Conditional equation (5) specifies the preferred optical properties for the material of at least one negative lens among the negative lenses in the final lens group GL in order to effectively correct chromatic aberration. By using an optical material with high positive anomalous partial dispersion as the material for the negative lens included in the final lens group GL, it becomes possible to correct the magnification chromatic aberration of the g line in the peripheral region in the over-correction direction.

[0045] In positive-lead variable magnification optical systems, the challenge in correcting chromatic aberration lies in how to simultaneously correct both the over-correction of g-line chromatic aberration that occurs at the wide-angle end and the under-correction of g-line chromatic aberration that occurs at the telephoto end.

[0046] To correct chromatic aberration across the entire magnification range, it is desirable to correct chromatic aberration at the telephoto end using the first lens group G1, where the peripheral light beam is incident at a high position relative to the optical axis, and to correct chromatic aberration at the wide-angle end using the front lens group GF, where the peripheral light beam is incident at a high position relative to the optical axis.

[0047] However, in the imaging optical system of the present invention, since miniaturization is the objective, the radius of curvature of each lens surface constituting the first lens group G1 cannot be reduced, and therefore the chromatic aberration at the telephoto end cannot be sufficiently corrected by the first lens group G1.

[0048] On the other hand, the final lens group GL has a large corrective effect on chromatic aberration because the position through which the peripheral light beam passes is high relative to the optical axis. Furthermore, because it is fixed relative to the image plane I during magnification, the change in the corrective effect on chromatic aberration due to magnification can be minimized.

[0049] Therefore, in the imaging optical system of the present invention, by using a highly dispersed optical material with large positive anomalous partial dispersion in the negative lens of the final lens group GL, the chromatic aberration of the g line is corrected in the over-angle direction so that the chromatic aberration of the g line becomes smaller at the telephoto end. As a result, the chromatic aberration of the g line in the over-angle direction, which becomes large at the wide-angle end, is corrected by the front lens group GF, thereby making it possible to suppress fluctuations in chromatic aberration of the magnification that occur when changing magnification.

[0050] When the lower limit of condition (5) is exceeded, and the positive anomalous partial dispersion of at least one negative lens among the negative lenses in the final lens group GL decreases, the correction effect of lateral chromatic aberration, including the second-order spectrum, in the final lens group GL at the telephoto end decreases, making it difficult to suppress lateral chromatic aberration.

[0051] Furthermore, regarding condition (5), it is preferable to limit its lower limit to 0.665, which will make the aforementioned effect more reliable.

[0052] Furthermore, in the imaging optical system of the present invention, it is desirable that the rear lens group GR has an object-side lens group GO that has a positive refractive power closest to the object, and that it has at least one focusing lens group GFcs that moves along the optical axis in focusing from an object at infinity to a nearby object, located closer to the image plane than the object-side lens group GO.

[0053] To achieve faster focusing, it is necessary to miniaturize the lens group that moves during focusing. By positioning the focusing lens group GFcs on the image plane side of the rear lens group GR, which has positive refractive power, the light rays expanded by the front lens group GF are converged by the object-side lens group GO and incident on the focusing lens group GFcs. This allows for a smaller lens diameter for the focusing lens group GFcs, enabling faster focusing.

[0054] Furthermore, in the imaging optical system of the present invention, the rear lens group GR has an aperture diaphragm S, which is fixed to the image plane I when changing magnification from the wide-angle end to the telephoto end, and it is desirable that all lens groups located on the image side of the aperture diaphragm S that move along the optical axis when changing magnification from the wide-angle end to the telephoto end are focusing lens groups GFcs that move along the optical axis when focusing from an object at infinity to an object at a close distance.

[0055] The aperture diaphragm S changes its diameter when the F-number is changed, so the overall diameter of the mechanism tends to be larger than the diameter of the aperture diaphragm S. Moving the mechanism of the large-diameter aperture diaphragm S during magnification requires an even larger mechanism, which is undesirable as it results in a larger lens barrel. Furthermore, if all the lens group that moves during magnification and focusing among the lens group located on the image plane side of the aperture diaphragm S is the focusing group, it can be driven by an actuator, thus eliminating the need for a complex mechanism. As a result, a mechanism for moving the aperture diaphragm S and the lens group on the image plane side of the aperture diaphragm S is unnecessary, making it possible to miniaturize the lens barrel.

[0056] Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional equation. (6) 2.50 <f1 / |fFW|<5.00 however, f1: Focal length of the first lens group G1 fFW: Focal length of the front lens group GF at the wide-angle end

[0057] Conditional equation (6) defines the ratio of the focal length of the first lens group G1 to the focal length of the front lens group GF at the wide-angle end. By satisfying conditional equation (6), the imaging optical system of the present invention achieves both miniaturization and correction of various aberrations.

[0058] If the refractive power of the first lens group G1 weakens when it exceeds the upper limit of condition (6), the correction effect of the first lens group G1 in the imaging optical system, particularly the correction effect of chromatic aberration at the telephoto end, becomes small, which is undesirable. Also, if the refractive power of the front lens group GF becomes strong at the wide-angle end, it becomes difficult to suppress coma aberration and astigmatism that occur in the front lens group GF.

[0059] If the refractive power of the first lens group G1 exceeds the lower limit of condition (6), the refractive power of each lens constituting the first lens group G1 increases, leading to an increase in the size of the first lens group G1, which is undesirable. Also, if the refractive power of the front lens group GF at the wide-angle end decreases, the magnification effect of the front lens group GF decreases, and the distance between the front lens group GF and the rear lens group GR at the wide-angle end increases. This increases the overall optical length of the imaging optical system at the wide-angle end, which is undesirable.

[0060] Furthermore, regarding conditional equation (6), it is preferable to limit its lower limit to 3.00 or its upper limit to 4.20 to make the aforementioned effect more certain.

[0061] Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional equation. (7) L1 / LTW < 0.17 however, L1: Length along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the first lens group G1. LTW: Total optical length of the imaging optical system at the wide-angle end

[0062] Conditional equation (7) defines the ratio of the length along the optical axis from the object-side surface to the image-side surface of the first lens group G1 to the total optical length of the imaging optical system at the wide-angle end. By satisfying conditional equation (7), the imaging optical system of the present invention can be miniaturized.

[0063] If the upper limit of condition (7) is exceeded and the length of the first lens group G1 along the optical axis increases, the weight of the first lens group G1 increases, which is undesirable because it increases the weight of the entire imaging optical system. Furthermore, the increased weight of the first lens group G1 causes it to move towards the object when changing magnification from the wide-angle end to the telephoto end, resulting in a large shift in the center of gravity of the imaging optical system, which is also undesirable.

[0064] Furthermore, regarding condition (7), it is preferable to limit its upper limit to 0.13, which will make the aforementioned effect more certain.

[0065] Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional equation among the negative lenses of the first lens group G1. (8)νd1n<50.0 (9) PgF1n + 0.0024 × νd1n < 0.677 however, νd1n: ​​The Abbe number with respect to the d line of at least one negative lens among the negative lenses of the first lens group G1. PgF1n: The partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses of the first lens group G1.

[0066] Conditional equations (8) and (9) specify the preferred optical properties for the material of at least one negative lens among the negative lenses of the first lens group G1 in order to effectively correct chromatic aberration. By using an optical material with negative anomalous partial dispersion and high dispersion as the material for the negative lens of the first lens group G1, it is possible to suppress the variation in magnification chromatic aberration, including the second-order spectrum, during magnification.

[0067] When the upper limit of condition (8) is exceeded and the Abbe number of the negative lens in the first lens group G1 becomes large, the achromatic effect of the first lens group G1 decreases, making it difficult to suppress chromatic aberration.

[0068] Furthermore, regarding condition (8), it is preferable to limit its upper limit to 41.0, which will make the aforementioned effect more certain.

[0069] When the upper limit of condition (9) is exceeded and the negative anomalous partial dispersion of the negative lens in the first lens group G1 decreases, the achromatic effect, including the secondary spectrum, in the first lens group G1 decreases, making it difficult to suppress chromatic aberration.

[0070] Furthermore, regarding condition (9), it is preferable to limit its upper limit to 0.672, which will make the aforementioned effect more certain.

[0071] Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional equation. (10) 0.55 < |fS| / fW < 1.20 however, fS: Focal length of the GS image stabilization lens group fW: Focal length of the imaging optical system at infinity focus at the wide-angle end.

[0072] Conditional equation (10) defines the ratio of the focal length of the vibration-damping lens group GS to the focal length of the imaging optical system at infinity focus at the wide-angle end. By satisfying conditional equation (10), the imaging optical system of the present invention achieves both high vibration damping effect and good imaging performance.

[0073] When the upper limit of condition (10) is exceeded and the refractive power of the GS image stabilization lens group decreases, the amount of movement during image stabilization increases, leading to a decrease in the responsiveness of the image stabilization operation and an increase in the size of the lens barrel.

[0074] When the lower limit of condition (10) is exceeded and the refractive power of the vibration-damping lens group GS increases, the aberration fluctuations during vibration damping become larger.

[0075] Furthermore, regarding conditional equation (10), it is preferable to limit its lower limit to 0.65 or its upper limit to 0.95 to make the aforementioned effect more reliable.

[0076] Furthermore, it is desirable that the imaging optical system of the present invention satisfies the following conditional equation. (11) BF / Ymax < 3.00 however, BF: Back focus in imaging optical systems Ymax: Maximum image height in an imaging optical system

[0077] Conditional equation (11) defines the ratio of the back focus in the imaging optical system to the maximum image height in the imaging optical system. By satisfying conditional equation (11), the imaging optical system of the present invention is made miniaturized. Here, the back focus in the present invention refers to the air-equivalent length on the optical axis from the lens surface on the image side of the final lens group GL to the image plane I.

[0078] If the back focus exceeds the upper limit of condition (11), the overall optical length of the imaging optical system increases, which is undesirable.

[0079] Furthermore, regarding condition (11), it is preferable to limit its upper limit to 2.30, which will make the aforementioned effect more certain.

[0080] The lens configurations, numerical examples, and corresponding values ​​for conditional expressions of each embodiment of the imaging optical system of the present invention are described below. In the following description, the lens configurations are described in order from the object side to the image plane side. Also, the notation Ln in the embodiments refers to the nth lens from the object side.

[0081] In the [surface data], the surface number is the number of the lens surface or aperture diaphragm 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 PgF indicates the partial dispersion ratio of the g line (wavelength 435.84 nm) and the F line (wavelength 486.13 nm).

[0082] The asterisk (*) next to the surface number indicates that the lens surface shape is aspherical. BF indicates the back focus, and the object surface distance indicates the distance from the subject to the first lens surface.

[0083] The (diaphragm) next to the face number indicates that an aperture diaphragm is located at that position. The radius of curvature relative to the plane or aperture diaphragm is indicated with ∞ (infinity).

[0084] The [Aspherical Data] section shows the values ​​of the coefficients that give the aspherical shape of the lens surface marked with an asterisk (*) in the [Surface Data] section. The shape of the aspherical surface is expressed by the following formula. In the following formula, y represents the displacement from the optical axis in the direction perpendicular to the optical axis, z represents the displacement (sag) in the direction of the optical axis from the intersection of the aspherical surface and the optical axis, r represents the radius of curvature of the reference sphere, and K represents the conic coefficient. The 4th, 6th, 8th, and 10th order aspherical coefficients are represented by A4, A6, A8, and A10, respectively.

[0085] TIFF0007849837000001.tif37170

[0086] The [Various Data] section shows the values ​​for focal length and other parameters at each focal length state.

[0087] The [Variable Interval Data] section shows the variable interval and BF values ​​for each shooting distance focus state.

[0088] The [Lens Group Data] shows the object-side face number for each lens group and the combined focal length of the entire group.

[0089] Furthermore, in the aberration diagrams corresponding to each embodiment, d, g, and C represent the d line, g line, and C line, respectively, and △S and △M represent the sagittal image plane and meridional image plane, respectively.

[0090] In addition, for all the specifications listed below, the units of focal length f, radius of curvature r, lens plane spacing d, and other lengths are millimeters (mm) unless otherwise specified. However, since equivalent optical performance can be obtained in both proportional magnification and proportional reduction in the optical system, this is not the only unit of measurement. [Examples]

[0091] Figure 1 is a lens configuration diagram of the imaging optical system according to Embodiment 1 of the present invention.

[0092] The imaging optical system of Example 1 consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The aperture diaphragm S is located within the fourth lens group G4. 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 changes, the distance between the fifth lens group G5 and the sixth lens group G6 changes, the first lens group G1 moves monotonically toward the object, and the fourth lens group G4 and the sixth lens group G6 are fixed relative to the image plane I.

[0093] The front lens group GF corresponds to the second lens group G2, the rear lens group GR corresponds to the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6, the object-side lens group GO corresponds to the third lens group G3, and the final lens group GL corresponds to the sixth lens group G6.

[0094] The fifth lens group G5 is the focusing lens group GFcs, which moves along the optical axis when focusing from an object at infinity to an object at a close distance.

[0095] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 with its convex surface facing the object, a biconvex lens L2, and a positive meniscus lens L3 with its convex surface facing the object.

[0096] The second lens group G2 consists of a negative meniscus lens L4 with its convex surface facing the object, a positive meniscus lens L5 with its convex surface facing the object, a biconcave lens L6, a positive meniscus lens L7 with its convex surface facing the image plane, and a negative meniscus lens L8 with its convex surface facing the image plane.

[0097] The third lens group G3 consists of a biconvex lens L9, in which both the R1 and R2 surfaces are aspherical.

[0098] The fourth lens group G4 consists of a biconvex lens L10, an aperture diaphragm S, a negative meniscus lens L11 with its convex surface facing the object, a biconvex lens L12, and a biconvex lens L13.

[0099] The fifth lens group G5 consists of a biconvex lens L14 and a biconcave lens L15, both of which have aspherical R1 and R2 surfaces.

[0100] The sixth lens group G6 consists of a cemented lens of a negative meniscus lens L16 with its convex surface facing the object and a positive meniscus lens L17 with its convex surface facing the object, a cemented lens of a biconvex lens L18 and a biconcave lens L19, a biconvex lens L20, and a negative meniscus lens L21 with aspherical R1 and R2 surfaces and its convex surface facing the image plane. The cemented lens of L16 and L17 is the vibration-damping lens group GS, and moves with a component perpendicular to the optical axis during vibration damping.

[0101] The specifications of the optical system according to Example 1 are shown below. Numerical Example 1 Unit: mm [Surface data] Face number rd nd vd PgF Object surface ∞ (d0) 1 157.1970 1.2000 1.76634 35.82 0.5792 2 74.7404 6.0850 1.49700 81.61 0.5389 3 -330.0940 0.1500 4 65.6434 5.6418 1.43700 95.10 0.5336 5 763.5059 (d5) 6 133.3397 0.9000 1.55032 75.50 0.5401 7 30.3907 2.7345 8 34.8642 2.2357 1.92119 23.96 0.6202 9 47.8947 2.7765 10 -150.3110 0.9000 1.71300 53.94 0.5442 11 83.6988 2.9085 12 -35.8560 2.4679 1.92286 20.88 0.6390 13 -27.1997 0.6217 14 -27.0761 1.5746 1.83481 42.72 0.5647 15 -70.8673 (d15) 16* 30.0653 4.8350 1.59271 66.97 0.5367 17* -101.9800 (d17) 18 41.5917 4.0604 1.49700 81.61 0.5389 19 -114.1310 1.2019 20 (aperture) ∞ 1.0000 21 159.2466 0.9000 1.95375 32.32 0.5901 22 25.9136 0.8774 23 34.2602 3.6878 1.49700 81.61 0.5389 24 -107.8400 0.1500 25 170.3157 2.8945 1.61997 63.88 0.5426 26 -48.2637 (d26) 27 403.5897 2.0487 2.05090 26.94 0.6052 28 -70.9652 0.2034 29* -183.0700 0.9000 1.76802 49.24 0.5516 30* 17.9524 (d30) 31 245.6632 0.9000 1.77250 49.63 0.5504 32 24.0758 1.7130 1.92286 20.88 0.6390 33 27.8057 1.0000 34 26.1342 6.0947 1.77250 49.63 0.5504 35 -24.5197 1.0129 1.86966 20.02 0.6435 36 61.4764 4.5104 37 280.6612 5.3975 1.95906 17.47 0.6598 38 -34.0926 0.7340 39* -33.1651 0.9000 1.59201 67.02 0.5358 40* 368.7869 (BF) Image plane ∞ [Aspherical data] 16th, 17th, 29th, 30th K 0.0000 0.0000 0.0000 0.0000 A4 -3.70287E-06 1.42522E-05 -1.76572E-05 -1.00061E-05 A6 9.04389E-09 4.26214E-09 1.34110E-08 -3.79049E-08 A8 -3.88102E-13 5.06609E-12 5.32156E-11 1.68284E-12 A10 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Pages 39 and 40 K 0.0000 0.0000 A4 -2.78280E-05 -3.40099E-05 A6 1.60355E-07 1.31472E-07 A8 -5.11466E-10 -3.70121E-10 A10 0.00000E+00 0.00000E+00 [Various Data] Zoom ratio 2.56 Wide-angle, Medium, Telephoto Focal length 51.50 88.04 132.00 F-number 2.92 2.92 2.92 Full angle of view 2ω 31.56 18.01 12.01 Image height Y 14.20 14.20 14.20 Lens length: 130.00 141.02 154.13 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.3000 27.3382 46.7040 d15 21.0911 7.0107 1.0000 d17 2.5443 1.6015 1.3583 d26 3.8978 5.2254 1.8284 d30 8.5482 7.2206 10.6176 BF 17.4008 17.4008 17.4008 Wide-angle, Medium, Telephoto d0 2129.9983 3446.8854 5194.3676 d5 1.3000 27.3382 46.7040 d15 21.0911 7.0107 1.0000 d17 2.5443 1.6015 1.3583 d26 4.2348 5.8633 2.6752 d30 8.2113 6.5828 9.7708 BF 17.4008 17.4008 17.4008 [Lens group data] Group starting plane focal length G1 1 113.28 G2 6 -32.59 G3 16 39.72 G4 18 48.25 G5 27 -34.45 G6 31 606.42 [Examples]

[0102] Figure 17 is a lens configuration diagram of the imaging optical system according to Embodiment 2 of the present invention.

[0103] The imaging optical system of Example 2 consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, an aperture diaphragm S, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having 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 changes, the distance between the fifth lens group G5 and the sixth lens group G6 decreases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases. The first lens group G1 moves monotonically toward the object, while the fifth lens group G5 and the seventh lens group G7 are fixed relative to the image plane I.

[0104] The front lens group GF corresponds to the second lens group G2 and the third lens group G3, the rear lens group GR corresponds to the fourth lens group G4, the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7, the object-side lens group GO corresponds to the fourth lens group G4, and the final lens group GL corresponds to the seventh lens group G7.

[0105] The sixth lens group G6 is the focusing lens group GFcs, which moves along the optical axis when focusing from an object at infinity to an object at a close distance.

[0106] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 with its convex surface facing the object, a biconvex lens L2, and a positive meniscus lens L3 with its convex surface facing the object.

[0107] The second lens group G2 consists of a cemented lens comprising a negative meniscus lens L4 with its convex surface facing the object and a positive meniscus lens L5 with its convex surface facing the object.

[0108] The third lens group G3 consists of a biconcave lens L6, a biconvex lens L7, and a biconcave lens L8.

[0109] The fourth lens group G4 consists of a biconvex lens L9, in which both the R1 and R2 surfaces are aspherical.

[0110] The fifth lens group G5 consists of a cemented lens comprising a negative meniscus lens L10 with its convex surface facing the object and a positive meniscus lens L11 with its convex surface facing the object, a cemented lens comprising a biconvex lens L12 and a negative meniscus lens L13 with its convex surface facing the image plane, and a biconvex lens L14.

[0111] The sixth lens group G6 consists of a positive meniscus lens L15 with a convex surface facing the image plane, and a biconcave lens L16 with both R1 and R2 surfaces being aspherical.

[0112] The seventh lens group G7 consists of a negative meniscus lens L17 with a convex surface facing the object and a positive meniscus lens with a convex surface facing the object. mosquito It consists of a cemented lens L18 and a negative meniscus lens L19 with a convex surface facing the image plane and aspherical R1 and R2 surfaces. The cemented lenses L17 and L18 form the vibration-damping lens group GS, which moves with a component perpendicular to the optical axis during vibration damping.

[0113] The specifications of the optical system according to Example 2 are shown below. Numerical Example 2 Unit: mm [Surface data] Face number rd nd vd PgF Object surface ∞ (d0) 1 101.9606 1.5000 1.78880 28.43 0.6009 2 66.0186 6.3941 1.49700 81.61 0.5389 3 -462.6850 0.1500 4 57.1433 5.2783 1.43700 95.10 0.5336 5 274.8881 (d5) 6 55.0778 0.9000 1.87070 40.73 0.5682 7 17.8699 2.5917 1.67300 38.26 0.5757 8 23.1108 (d8) 9 -38.2877 0.9000 1.55032 75.50 0.5401 10 181.8696 0.1500 11 39.5096 3.4083 1.92286 20.88 0.6390 12 -156.0450 1.2173 13 -45.7125 0.9000 1.91082 35.25 0.5822 14 560.6244 (d14) 15* 31.0289 4.3028 1.61881 63.85 0.5417 16* -102.0810 (d16) 17 (aperture) ∞ 1.0000 18 34.2989 0.9000 1.92119 23.96 0.6202 19 18.4243 2.8303 1.49700 81.61 0.5389 20 27.5000 0.7203 21 33.8891 6.4167 1.49700 81.61 0.5389 22 -19.1838 0.9000 1.92286 20.88 0.6390 23 -36.1468 0.1500 24 154.2758 3.1400 1.92286 20.88 0.6390 25 -44.5275 (d25) 26 -41.1448 1.8158 1.92286 20.88 0.6390 27 -29.4968 0.1500 28* -55.4120 0.9391 1.61881 63.85 0.5417 29* 12.6232 (d29) 30 24.5124 0.8500 1.92286 20.88 0.6390 31 17.4778 3.5164 1.77250 49.63 0.5504 32 222.0324 3.1493 33* -13.5181 2.0064 1.49710 81.56 0.5385 34* -19.4535 (BF) Image plane ∞ [Aspherical data] Pages 15, 16, 28, and 29 K 0.0000 0.0000 0.0000 0.0000 A4 1.94080E-06 1.98221E-05 -3.79758E-05 -7.26383E-05 A6 1.54463E-08 -6.19918E-09 1.58714E-07 -1.22650E-07 A8 -7.12289E-11 -5.80620E-11 -6.67702E-10 -1.80017E-09 A10 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Pages 33 and 34 K 0.0000 0.0000 A4 3.08634E-04 2.47981E-04 A6 -1.46504E-06 -1.18744E-06 A8 5.78815E-09 3.32949E-09 A10 0.00000E+00 0.00000E+00 [Various Data] Zoom ratio 2.59 Wide-angle, Medium, Telephoto Focal length 51.00 84.98 132.00 F number 2.91 2.91 2.91 Full angle of view 2ω 30.33 18.08 11.74 Image height Y 14.20 14.20 14.20 Lens length: 120.00, 137.13, 145.00 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.3000 26.4143 41.9795 d8 7.4491 6.3225 4.9644 d14 14.1504 8.0511 1.0000 d16 2.2547 1.5000 2.2103 d25 5.0932 4.1731 1.6537 d29 3.4991 4.4192 6.9386 BF 30.0768 30.0768 30.0768 Wide-angle, Medium, Telephoto d0 2021.6393 3323.1259 5180.2512 d5 1.3000 26.4143 41.9795 d8 7.4491 6.3225 4.9644 d14 14.1504 8.0511 1.0000 d16 2.2547 1.5000 2.2103 d25 5.3163 4.5420 2.2052 d29 3.2760 4.0503 6.3871 BF 30.0768 30.0768 30.0768 [Lens group data] Group starting plane focal length G1 1 96.21 G2 6 -41.93 G3 9 -109.48 G4 15 38.94 G5 17 32.60 G6 26 -19.26 G7 30 59.96 [Examples]

[0114] Figure 33 is a lens configuration diagram of the imaging optical system according to Embodiment 3 of the present invention.

[0115] The imaging optical system of Example 3 consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The aperture diaphragm S is located within the fourth lens group G4. 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 the distance between the fifth lens group G5 and the sixth lens group G6 decreases. The first lens group G1 moves monotonically toward the object, while the fourth lens group G4 and the sixth lens group G6 are fixed relative to the image plane I.

[0116] The front lens group GF corresponds to the second lens group G2, the rear lens group GR corresponds to the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6, the object-side lens group GO corresponds to the third lens group G3, and the final lens group GL corresponds to the sixth lens group G6.

[0117] The fifth lens group G5 is the focusing lens group GFcs, which moves along the optical axis when focusing from an object at infinity to an object at a close distance.

[0118] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 with its convex surface facing the object, a biconvex lens L2, and a positive meniscus lens L3 with its convex surface facing the object.

[0119] The second lens group G2 consists of a negative meniscus lens L4 with its convex side facing the object, a biconcave lens L5, a biconvex lens L6, and a biconcave lens L7.

[0120] The third lens group G3 consists of a biconvex lens L8, in which both the R1 and R2 surfaces are aspherical.

[0121] The fourth lens group G4 consists of a biconvex lens L9, a positive meniscus lens L10 with its convex surface facing the object, an aperture diaphragm S, a biconcave lens L11, and a positive meniscus lens L12 with its convex surface facing the image plane.

[0122] The fifth lens group G5 consists of a cemented lens comprising a negative meniscus lens L13 with its convex surface facing the object and a positive meniscus lens L14 with its convex surface facing the object.

[0123] The sixth lens group G6 consists of a cemented lens comprising a positive meniscus lens L15 with its convex surface facing the image plane and a biconcave lens L16 with an aspherical R2 surface, and a biconvex lens L17. The cemented lens of L15 and L16 is the vibration-damping lens group GS, and moves with a component perpendicular to the optical axis during vibration damping.

[0124] The specifications of the optical system according to Example 3 are shown below. Numerical Example 3 Unit: mm [Surface data] Face number rd nd vd PgF Object surface ∞ (d0) 1 105.2785 1.8000 1.77047 29.74 0.5951 2 64.3162 6.9874 1.49700 81.61 0.5389 3 -399.3190 0.1500 4 54.1632 6.1609 1.43700 95.10 0.5336 5 397.9567 (d5) 6 1271.4610 0.9000 1.77250 49.63 0.5504 7 25.3690 3.9960 8 -43.3814 0.9000 1.55032 75.50 0.5401 9 350.5870 0.1500 10 46.1248 3.1439 1.92119 23.96 0.6202 11 -270.4890 1.5674 12 -43.0197 0.9000 1.77250 49.63 0.5504 13 254.3148 (d13) 14* 30.1953 4.5715 1.55332 71.69 0.5404 15* -171.0580 (d15) 16 40.8986 4.3056 1.59282 68.62 0.5440 17 -102.5480 0.1500 18 86.3297 2.2810 1.55032 75.50 0.5401 19 1116.6830 1.5610 20 (aperture) ∞ 1.2234 21 -257.7980 0.9000 1.73037 32.23 0.5899 22 22.0510 3.1096 23 -138.9600 2.7156 1.49700 81.61 0.5389 24 -33.5734 (d24) 25 25.2922 0.9000 1.73037 32.23 0.5899 26 19.0764 3.4995 1.61997 63.88 0.5426 27 78.5849 (d27) 28 -152.9980 2.4754 1.77047 29.74 0.5951 29 -37.6723 0.9000 1.59201 67.02 0.5358 30* 24.1827 2.5703 31 88.8971 2.9492 1.48749 70.44 0.5306 32 -58.5852 (BF) Image plane ∞ [Aspherical data] Surface 14, Surface 15, Surface 30 K 0.0000 0.0000 0.0000 A4 -3.77793E-06 8.92318E-06 -7.29476E-07 A6 -2.16177E-09 -2.09760E-09 -2.19744E-08 A8 1.94118E-11 2.39209E-11 8.77000E-11 A10 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.69 Wide angle, Medium, Telephoto Focal length 51.00, 86.49, 137.40 F-number 2.92, 2.92, 2.92 Full picture angle 2ω 30.84, 17.96, 11.24 Image height Y 14.20, 14.20, 14.20 Total lens length 125.00, 145.30, 150.00 [Variable interval data] Wide angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.7317, 28.5482, 41.1913 ​​​​​​​​BF 29.4658 29.4659 29.4659 Wide angle, Medium, Telephoto d0 2084.0638 3378.2126 5432.7395 d5 1.7317 28.5482 41.1913 d13 12.6738 9.1723 1.3000 d15 4.5835 1.5647 1.5000 d24 2.7541 7.3200 11.6873 d27 13.0233 8.4574 4.0901 BF 29.4659 29.4659 29.4659 [Lens group data] Group, Starting surface, Focal length G1 1 89.40 G2 6 -22.51 G3 14 46.76 G4 16 186.72 G5 25 63.29 G6 28 -101.84

Example

[0125] Figure 49 is a lens configuration diagram of the imaging optical system according to Example 4 of the present invention.

[0126] The imaging optical system of Example 4 consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, an aperture diaphragm S, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having 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 changes, 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 changes, the distance between the sixth lens group G6 and the seventh lens group G7 changes, the first lens group G1 moves monotonically toward the object, and the fifth lens group G5 and the seventh lens group G7 are fixed relative to the image plane I.

[0127] The front lens group GF corresponds to the second lens group G2 and the third lens group G3, the rear lens group GR corresponds to the fourth lens group G4, the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7, the object-side lens group GO corresponds to the fourth lens group G4, and the final lens group GL corresponds to the seventh lens group G7.

[0128] The second lens group G2 and the sixth lens group G6 are the focusing lens group GFcs, which move along the optical axis when focusing from an object at infinity to an object at a close distance.

[0129] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 with its convex surface facing the object, a biconvex lens L2, and a positive meniscus lens L3 with its convex surface facing the object.

[0130] The second lens group G2 consists of a negative meniscus lens L4 with a convex surface facing the object and both the R1 and R2 surfaces being aspherical.

[0131] The third lens group G3 consists of a biconcave lens L5, a biconvex lens L6, and a biconcave lens L7.

[0132] The fourth lens group G4 consists of a biconvex lens L8 with both the R1 surface and the R2 surface being aspherical surfaces.

[0133] The fifth lens group G5 consists of a plano-convex lens L9 with a plane facing the object side, a cemented lens of a negative meniscus lens L10 with a convex surface facing the object side and a biconvex lens L11, a cemented lens of a biconcave lens L12 and a biconvex lens L13.

[0134] The sixth lens group G6 consists of a negative meniscus lens L14 with a convex surface facing the image plane side.

[0135] The seventh lens group G7 consists of a negative meniscus lens L15 with a convex surface facing the object side and a cemented lens of a positive meniscus lens L16 with a convex surface facing the object side, a biconvex lens L17, a biconcave lens L18, a biconvex lens L19, and a negative meniscus lens L20 with convex surfaces facing the image plane side and with both the R1 surface and the R2 surface being aspherical surfaces. The cemented lens of L15 and L16 is an anti-vibration lens group GS, which moves with a component in a direction perpendicular to the optical axis during anti-vibration. mosquito

[0136] The specifications of the optical system according to Example 4 are shown below. Numerical Example 4 Unit: mm [Surface Data] Surface number r d nd vd PgF Object surface ∞ (d0) 1 110.8865 1.2000 1.75000 28.95 0.5948 2 71.7917 6.2404 1.49700 81.61 0.5389 3 -468.1850 0.1500 4 66.3984 4.9658 1.43700 95.10 0.5336 5 354.5132 (d5) 6* 206.4825 0.9000 1.80610 40.73 0.5694 7* 38.1769 (d7) 8 -43.3166 0.9001 1.49700 81.61 0.5389 9 206.7869 0.1500 10 63.4714 3.6184 1.92119 23.96 0.6202 11 -64.2933 1.1206 12 -36.2567 0.9000 1.87070 40.73 0.5682 13 171.7287 (d13) 14* 32.5749 3.9079 1.85135 40.10 0.5695 15* -610.7880 (d15) 16 (aperture) ∞ 1.0000 17 ∞ 3.0436 1.49700 81.61 0.5389 18 -45.8068 0.1500 19 28.7905 0.9000 1.90110 27.06 0.6072 20 15.9000 5.2729 1.49700 81.61 0.5389 21 -780.1410 0.3133 22 -634.4430 0.9000 1.71736 29.50 0.6040 23 42.7268 3.2393 1.55032 75.50 0.5401 24 -66.9993 (d24) 25 60.5662 0.9000 1.72916 54.67 0.5453 26 17.1482 (d26) 27 309.5050 0.9000 1.95375 32.32 0.5901 28 18.1151 2.5722 1.92286 20.88 0.6390 29 33.8199 1.0521 30 27.1822 3.7032 1.87070 40.73 0.5682 31 -503.3710 0.9679 32 -71.3834 0.9000 1.92286 20.88 0.6390 33 41.2602 5.0126 34 99.5610 5.2778 2.00069 25.46 0.6136 35 -30.9639 1.2587 36* -21.1606 0.8999 1.55332 71.69 0.5404 37* -50.0557 (BF) Image plane ∞ [Aspherical data] 6 sides 7 sides 14 sides 15 sides K 0.0000 0.0000 0.0000 0.0000 A4 5.60046E-06 4.09101E-06 -5.70420E-07 1.17204E-05 A6 -2.06304E-10 1.49883E-10 7.97332E-09 7.15638E-09 A8 2.21510E-11 2.73090E-11 5.79324E-12 4.89953E-12 A10 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Pages 36 and 37 K 0.0000 0.0000 A4 1.49273E-05 3.82329E-06 A6 5.01494E-08 2.70391E-08 A8 -4.63894E-11 -3.30174E-11 A10 0.00000E+00 0.00000E+00 [Various Data] Zoom ratio 2.66 Wide-angle, Medium, Telephoto Focal length 51.12 86.61 136.00 F-number 2.92 2.92 2.92 Full angle of view 2ω 31.04 17.96 11.43 Image height Y 14.20 14.20 14.20 Lens length: 120.00 135.68 144.00 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.2000 27.4112 46.0389 d7 5.7801 6.3376 4.5795 d13 19.0905 8.9233 1.0000 d15 3.0531 2.1335 1.5054 d24 4.7209 4.8103 1.2002 d26 6.6389 6.5496 10.1597 BF 17.2000 17.2000 17.2000 Wide-angle, Medium, Telephoto d0 2048.3036 3399.3582 5343.6304 d5 1.9740 27.6345 45.9889 d7 5.0062 6.1142 4.6295 d13 19.0905 8.9233 1.0000 d15 3.0531 2.1335 1.5054 d24 5.0572 5.3909 2.0724 d26 6.3027 5.9690 9.2875 BF 17.2000 17.2000 17.2000 [Lens group data] Group starting plane focal length G1 1 104.25 G2 6 -58.24 G3 8 -73.29 G4 14 36.43 G5 16 48.75 G6 25 -33.10 G7 27 181.16 [Examples]

[0137] Figure 65 is a lens configuration diagram of the imaging optical system according to Embodiment 5 of the present invention.

[0138] The imaging optical system of Example 5 consists of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, an aperture diaphragm S, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having negative 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 increases, 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 changes, the distance between the fifth lens group G5 and the sixth lens group G6 decreases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases. The first lens group G1 moves monotonically toward the object, while the fifth lens group G5 and the seventh lens group G7 are fixed relative to the image plane I.

[0139] The front lens group GF corresponds to the second lens group G2 and the third lens group G3, the rear lens group GR corresponds to the fourth lens group G4, the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7, the object-side lens group GO corresponds to the fourth lens group G4, and the final lens group GL corresponds to the seventh lens group G7.

[0140] The sixth lens group G6 is the focusing lens group GFcs, which moves along the optical axis when focusing from an object at infinity to an object at a close distance.

[0141] The first lens group G1 consists of a cemented lens comprising a negative meniscus lens L1 with its convex surface facing the object, a biconvex lens L2, and a positive meniscus lens L3 with its convex surface facing the object.

[0142] The second lens group G2 consists of a negative meniscus lens L4 with its convex surface facing the object, a biconcave lens L5, and a biconvex lens L6.

[0143] The third lens group G3 consists of a negative meniscus lens L7 with a convex surface facing the image plane.

[0144] The fourth lens group G4 consists of a biconvex lens L8, in which both the R1 and R2 surfaces are aspherical.

[0145] The fifth lens group G5 consists of a cemented lens of a plano-concave lens L9 with its plane facing the object and a positive meniscus lens L10 with its convex surface facing the object, a biconvex lens L11, a cemented lens of a negative meniscus lens L12 with its convex surface facing the object and a biconvex lens L13, and a biconvex lens L14.

[0146] The sixth lens group G6 consists of a negative meniscus lens L15 with a convex surface facing the object and both the R1 and R2 surfaces being aspherical.

[0147] The seventh lens group G7 consists of a negative meniscus lens L16 with a convex surface facing the object and a positive meniscus lens with a convex surface facing the object. mosquito The lens consists of a cemented lens L17, a biconvex lens L18, and a negative meniscus lens L19 with its convex surface facing the image plane and its R1 and R2 surfaces being aspherical. The cemented lenses L16 and L17 form the vibration-damping lens group GS, which moves with a component perpendicular to the optical axis during vibration damping.

[0148] The specifications of the optical system according to Example 5 are shown below. Numerical Example 5 Unit: mm [Surface data] Face number rd nd vd PgF Object surface ∞ (d0) 1 115.2505 1.2000 1.71950 31.75 0.5887 2 59.5948 7.2300 1.49700 81.61 0.5389 3 -456.0790 0.1500 4 51.4474 6.1955 1.43700 95.10 0.5336 5 288.6756 (d5) 6 81.0185 0.9000 1.76385 48.49 0.5589 7 22.2965 5.1548 8 -41.9688 0.9000 1.52841 76.46 0.5396 9 87.9551 0.1500 10 39.5712 4.8931 1.83080 24.95 0.6072 11 -56.0880 (d11) 12 -36.1968 0.9000 2.05090 26.94 0.6052 13 -197.3260 (d13) 14* 40.4838 3.7842 1.73077 40.50 0.5715 15* -88.7713 (d15) 16 (aperture) ∞ 1.0000 17 ∞ 0.9000 1.95375 32.32 0.5901 18 19.5571 2.9544 1.92286 18.90 0.6495 19 31.7771 0.1500 20 29.8000 5.1165 1.49700 81.61 0.5389 21 -43.3814 0.1500 22 63.6903 0.9000 1.89286 20.36 0.6393 23 22.5934 5.2321 1.49700 81.61 0.5389 24 -60.1293 1.7570 25 33.9787 4.3506 1.61340 44.27 0.5633 26 -47.0434 (d26) 27* 130.1364 0.9000 1.58913 61.25 0.5374 28* 12.8537 (d28) 29 109.1863 0.9000 1.88300 40.81 0.5656 30 18.0034 2.6882 1.84666 23.78 0.6192 31 29.4960 6.8907 32 136.3965 4.8732 1.83481 42.72 0.5647 33 -27.2642 2.5677 34* -16.7437 0.9843 1.49710 81.56 0.5385 35* -55.8353 (BF) Image plane ∞ [Aspherical data] Pages 14, 15, 27, and 28 K 0.0000 0.0000 0.0000 0.0000 A4 2.95068E-08 1.64848E-05 -2.20521E-06 -1.29514E-05 A6 1.62921E-08 6.90270E-09 -5.02595E-08 -1.37735E-07 A8 -2.64797E-11 -2.05727E-11 2.45877E-10 -8.14122E-10 A10 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Pages 34 and 35 K 0.0000 0.0000 A4 4.40735E-06 -3.39E-05 A6 1.31029E-07 5.23E-08 A8 -3.39504E-10 -3.54E-10 A10 0.00000E+00 0.00000E+00 [Various Data] Zoom ratio 2.68 Wide-angle, Medium, Telephoto Focal length 51.00 86.00 136.80 F-number 2.92 2.92 2.92 Full angle of view 2ω 30.87 18.17 11.44 Image height Y 14.20 14.20 14.20 Lens length: 125.00, 138.43, 150.00 [Variable interval data] Wide-angle, Medium, Telephoto d0 ∞ ∞ ∞ d5 1.2000 23.9706 39.4864 d11 4.3362 4.9316 5.5651 d13 16.0073 6.4395 1.0000 d15 2.1719 1.8023 2.6639 d26 5.3486 4.7088 1.6793 d28 5.3370 5.9768 9.0063 BF 16.8266 16.8266 16.8266 Wide-angle, Medium, Telephoto d0 2012.8838 3342.2404 5323.5256 d5 1.2000 23.9706 39.4864 d11 4.3362 4.9316 5.5651 d13 16.0073 6.4395 1.0000 d15 2.1719 1.8023 2.6639 d26 5.5744 5.0826 2.2003 d28 5.1112 5.6030 8.4853 BF 16.8266 16.8266 16.8266 [Lens group data] Group starting plane focal length G1 1 94.91 G2 6 -279.77 G3 12 -42.30 G4 14 38.52 G5 16 28.06 G6 27 -24.28 G7 29 -403.73

[0149] The following shows the corresponding values ​​for the conditional expressions in each of the above embodiments. [Conditional expression corresponding value] Conditional Expression / Example 1 2 3 4 5 (1) 0.30 <f1 / fT<1.50 0.86 0.73 0.65 0.77 0.69 (2) 0.80<|f1n| / f1<4.00 1.65 2.51 2.45 2.64 0.00 (3) 20.0 <LTT×FnoT / Ymax<50.0 31.7 29.7 30.8 29.6 30.8 (4) PgFFp+0.0022×νdFp<0.678 0.673 0.660 0.673 0.673 0.662 (5) 0.658 <PgFLn+0.0021×νdLn 0.686 0.683 0.677 0.683 0.710 0.677 0.710 0.691 (6) 2.50 <f1 / |fFW|<5.00 3.48 3.43 3.97 3.46 3.09 (7) L1 / LTW<0.17 0.10 0.11 0.12 0.10 0.12 (8) νd1n<50.0 35.82 28.43 29.74 28.95 31.75 (9) PgF1n+0.0024×νd1n<0.677 0.665 0.669 0.666 0.664 0.665 (10) 0.55<|fS| / fW<1.20 0.83 0.76 0.79 0.76 0.88 (11) BF / Ymax<3.00 1.23 2.12 2.08 1.21 1.18

[0150] Each of the embodiments described above illustrates a specific implementation example of the present invention. The technical scope of the present invention is not limited to the embodiments of each example.

[0151] In addition to the embodiments described above, the present invention can be implemented by various modified embodiments. Modified embodiments in which the constituent elements of the present invention are altered, modified, limited, substituted, added, or / and numerical values ​​are changed or / and numerical ranges are limited, without departing from the technical scope of the present invention, are included in the technical scope of the present invention or are equivalent to the present invention. Furthermore, these modified embodiments will achieve the same effects as the embodiments described above.

[0152] The present invention can also be configured in any of the following ways. [Section 1] Starting from the object side, the lens consists of a first lens group G1 with positive refractive power, a front lens group GF with negative refractive power, and a rear lens group GR 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 front lens group GF increases, the distance between the front lens group GF and the rear lens group GR decreases, and the first lens group G1 moves monotonically toward the object. The first lens group G1 has at least one negative lens, The front lens group GF consists of a lens group having a negative refractive power of 1 or more. The rear lens group GR is positioned closest to the image plane, is fixed to the image plane I, and has a final lens group GL that does not move during magnification and focusing. The final lens group GL has a vibration-damping lens group GS that is movable in a direction including a component perpendicular to the optical axis, An imaging optical system characterized by satisfying the following conditional equation. (1) 0.30 <f1 / fT<1.50 (2) 0.80 < |f1n| / f1 < 4.00 (3) 20.0 <LTT×FnoT / Ymax<50.0 however, f1: Focal length of the first lens group G1 fT: Focal length of the imaging optical system at infinity focus at the telephoto end. f1n: The focal length of at least one negative lens among the negative lenses in the first lens group G1. LTT: Total optical length of the imaging optical system at the telephoto end FnoT: The maximum aperture value of the imaging optical system when focused at infinity at the telephoto end. Ymax: Maximum image height in an imaging optical system [Section 2] The imaging optical system according to [Item 1], characterized in that the front lens group GF has positive lenses, and the positive lens located closest to the object satisfies the following condition. (4) PgFFp + 0.0022 × νdFp < 0.678 however, PgFFp: The partial dispersion ratio of the g-line and F-line of the positive lens located closest to the object among the positive lenses in the front lens group GF. νdFp: The Abbe number with respect to the d line of the positive lens located closest to the object among the positive lenses in the front lens group GF. [Section 3] The imaging optical system according to [Item 1] or [Item 2], characterized in that the final lens group GL has negative lenses, and at least one of the negative lenses satisfies the following condition. (5) 0.658 <PgFLn+0.0021×νdLn however, PgFLn: Partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses in the final lens group GL. νdLn: Abbe number with respect to the d line of at least one negative lens among the negative lenses of the final lens group GL. [Section 4] The imaging optical system according to any one of [Clause 1] to [Clause 3], characterized in that the rear lens group GR has an object-side lens group GO having the most positive refractive power on the object side, and has at least one focusing lens group GFcs that moves along the optical axis in focusing from an object at infinity to an object at a close distance, located on the image plane side of the object-side lens group GO. [Section 5] The imaging optical system according to any one of [Item 1] to [Item 4], characterized in that the rear lens group GR has an aperture diaphragm S, the aperture diaphragm S is fixed with respect to the image plane I when the magnification changes from the wide-angle end to the telephoto end, and all lens groups located on the image side of the aperture diaphragm S that move along the optical axis when the magnification changes from the wide-angle end to the telephoto end are the focusing lens group GFcs that move along the optical axis when focusing from an object at infinity to an object at close range. [Section 6] An imaging optical system according to any one of [Item 1] to [Item 5], characterized in that it satisfies the following conditional formulas. (6) 2.50 <f1 / |fFW|<5.00 however, f1: Focal length of the first lens group G1 fFW: Focal length of the front lens group GF at the wide-angle end [Section 7] An imaging optical system according to any one of [Item 1] to [Item 6], characterized in that it satisfies the following conditional formulas. (7) L1 / LTW < 0.17 however, L1: Length along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the first lens group G1. LTW: Total optical length of the imaging optical system at the wide-angle end [Section 8] The imaging optical system according to any one of [Item 1] to [Item 7], characterized in that at least one of the negative lenses in the first lens group G1 satisfies the following conditional expression. (8)νd1n<50.0 (9) PgF1n + 0.0024 × νd1n < 0.677 however, νd1n: ​​The Abbe number with respect to the d line of at least one negative lens among the negative lenses of the first lens group G1. PgF1n: The partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses of the first lens group G1. [Section 9] An imaging optical system according to any one of [Item 1] to [Item 8], characterized in that it satisfies the following conditional formulas. (10) 0.55 < |fS| / fW < 1.20 however, fS: Focal length of the GS image stabilization lens group fW: Focal length of the imaging optical system at infinity focus at the wide-angle end. [Section 10] An imaging optical system according to any one of [Item 1] to [Item 9], characterized in that it satisfies the following conditional formulas. (11) BF / Ymax < 3.00 however, BF: Back focus in imaging optical systems Ymax: Maximum image height in an imaging optical system [Explanation of Symbols]

[0153] G1 First Lens Group GF front lens group GR rear lens group GL Final Lens Group GS Image Stabilizing Lens Group GO object-side lens group GFcs focusing lens group G2 Second Lens Group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group S Aperture diaphragm I image plane

Claims

1. Starting from the object side, the lens consists of a first lens group G1 with positive refractive power, a front lens group GF with negative refractive power, and a rear lens group GR 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 front lens group GF increases, the distance between the front lens group GF and the rear lens group GR decreases, and the first lens group G1 moves monotonically toward the object. The first lens group G1 has at least one negative lens, The front lens group GF consists of one or two lens groups having negative refractive power, and when the front lens group GF consists of two lens groups having negative refractive power, when changing magnification from the wide-angle end to the telephoto end, the distance between each of the two lens groups having negative refractive power and the lens group adjacent to that lens group changes. The rear lens group GR has a final lens group GL that is positioned closest to the image plane and fixed to the image plane I, and does not move during magnification and focusing, an object-side lens group GO that has positive refractive power and is closest to the object, and at least one focusing lens group GFcs that moves along the optical axis when focusing from an infinity object to a near-field object, located closer to the image plane than the object-side lens group GO, and consists of a total of four lens groups, and when magnification is changed from the wide-angle end to the telephoto end, the distance between each of the four lens groups constituting the rear lens group GR and the lens group adjacent to that lens group changes, and has an aperture diaphragm S, the aperture diaphragm S is fixed to the image plane I when magnification is changed from the wide-angle end to the telephoto end, and all lens groups located closer to the image plane than the aperture diaphragm S that move along the optical axis when magnification is changed from the wide-angle end to the telephoto end are the focusing lens group GFcs. The final lens group GL has a vibration-damping lens group GS that is movable in a direction including a component perpendicular to the optical axis, An imaging optical system characterized by satisfying the following conditions. (1) 0.30<f1 / fT<1.50 (2) 0.80<|f1n| / f1<4.00 (3) 20.0<LTT×FnoT / Ymax<50.0 however, f1: Focal length of the first lens group G1 fT: Focal length of the imaging optical system at infinity focus at the telephoto end. f1n: The focal length of at least one negative lens among the negative lenses in the first lens group G1. LTT: Total optical length of the imaging optical system at the telephoto end FnoT: The maximum aperture value of the imaging optical system when focused at infinity at the telephoto end. Ymax: Maximum image height in an imaging optical system

2. The imaging optical system according to claim 1, characterized in that the front lens group GF has positive lenses, and the positive lens located closest to the object satisfies the following condition. (4) PgFFp+0.0022×νdFp<0.678 however, PgFFp: Partial dispersion ratio with respect to the g-line and F-line of the positive lens located closest to the object among the positive lenses of the front lens group GF. νdFp: The Abbe number with respect to the d line of the positive lens located closest to the object among the positive lenses of the front lens group GF.

3. The imaging optical system according to claim 1, characterized in that the final lens group GL has negative lenses, and at least one of the negative lenses satisfies the following condition. (5) 0.658<PgFLn+0.0021×νdLn however, PgFLn: Partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses in the final lens group GL. νdLn: Abbe number with respect to the d line of at least one negative lens among the negative lenses of the final lens group GL.

4. The imaging optical system according to claim 1, characterized in that it satisfies the following conditional formula. (6) 2.50<f1 / |fFW|<5.00 however, f1: Focal length of the first lens group G1 fFW: Focal length of the front lens group GF at the wide-angle end

5. The imaging optical system according to claim 1, characterized in that it satisfies the following conditional formula. (7) L1 / LTW<0.17 however, L1: Length along the optical axis from the lens surface closest to the object to the lens surface closest to the image in the first lens group G1. LTW: Total optical length of the imaging optical system at the wide-angle end

6. The imaging optical system according to claim 1, characterized in that at least one of the negative lenses in the first lens group G1 satisfies the following conditional expression. (8) νd1n<50.0 (9) PgF1n+0.0024×νd1n<0.677 however, νd1n: ​​The Abbe number with respect to the d line of at least one negative lens among the negative lenses of the first lens group G1. PgF1n: The partial dispersion ratio with respect to the g-line and F-line of at least one negative lens among the negative lenses of the first lens group G1.

7. The imaging optical system according to claim 1, characterized in that it satisfies the following conditional formula. (10) 0.55<|fS| / fW<1.20 however, fS: Focal length of the GS image stabilization lens group fW: Focal length of the imaging optical system at infinity focus at the wide-angle end

8. The imaging optical system according to claim 1, characterized in that it satisfies the following conditional formula. (11) BF / Ymax<3.00 however, BF: Back focus in imaging optical systems Ymax: Maximum image height in an imaging optical system

Images