Variable power optical system

Abstract

To provide a variable power optical system in which various aberrations such as spherical aberration and curvature of field are suppressed over the entire variable power range in spite of a relatively small size by making a change in an interval between lens groups appropriate.SOLUTION: The zoom lens includes, in order from an object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, and an image surface side lens group GR, and during zooming from a wide angle end to a telephoto end, an air interval between the first lens group G1 and the second lens group G2 decreases, an air interval between the second lens group G2 and the third lens group G3 changes, an air interval between the third lens group G3 and the image surface side lens group GR increases, and predetermined conditional expressions are satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system suitable for use as a photographic lens in imaging devices such as still cameras and video cameras, and to a variable magnification optical system that has a relatively large aperture ratio, is small and lightweight, and corrects various aberrations such as field curvature over the entire variable magnification range. [Background technology]

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

[0003] On the other hand, with the rise of smartphones and other devices, there is a growing demand for optical systems suitable for digital cameras with large image sensors to take advantage of larger bokeh in order to differentiate themselves from other devices.

[0004] However, optical systems with bright F-numbers that enable large bokeh expressions that have been proposed up until now often employ complex lens configurations to correct various aberrations such as spherical aberration and field curvature, making it difficult to achieve compactness.

[0005] Examples of patent documents relating to the above are disclosed in Patent Document 1 and Patent Document 2. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-196572 [Patent Document 2] Patent Publication No. 2021-139930 Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 proposes a variable magnification optical system that has a relatively large aperture ratio and a relatively short overall lens length. However, the variable magnification optical system in Patent Document 1 is undesirable because, in examples in which the overall lens length does not change with magnification, the curvature of field tends to worsen at intermediate focal lengths, and axial chromatic aberration and chromatic aberration of magnification tend to worsen at the telephoto end.

[0008] Patent Document 2 proposes a variable magnification optical system that has a relatively large aperture ratio and suppresses various aberrations throughout the entire variable magnification range. However, the variable magnification optical system in Patent Document 2 is not preferable because the overall lens length changes significantly when the magnification is changed and it is necessary to drive the lens group closest to the object, which is heavy, making it difficult to achieve both mechanical strength and lightweight design.

[0009] The present invention aims to provide a variable magnification optical system that is relatively compact yet suppresses aberrations such as spherical aberration and field curvature over the entire variable magnification range by appropriately changing the spacing between lens groups. [Means for solving the problem]

[0010] The first invention, which is a means for solving the above problem, is a variable magnification optical system that is composed of, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and an image-plane side lens group GR, and when varying magnification from the wide-angle end to the telephoto end, the air space between the first lens group G1 and the second lens group G2 decreases, the air space between the second lens group G2 and the third lens group G3 changes, and the air space between the third lens group G3 and the image-plane side lens group GR increases, and is characterized by satisfying the following conditional expression: (1)-0.08 < (D23T-D23W) / (D12W-D12T) < 0.08 (2)0.08 < (D23N-D23W) / (D12W-D12T) < 0.40 (3)0.08 < (D23N-D23T) / (D12W-D12T) < 0.40 (4)0.50 < (D34T-D34W) / (D12W-D12T) < 2.00 however, D12W: Distance between the first lens group G1 and the second lens group G2 at the wide-angle end D12T: Distance between the first lens group G1 and the second lens group G2 at the telephoto end D23W: Distance between the second lens group G2 and the third lens group G3 at the wide-angle end D23N: Distance between the second lens group G2 and the third lens group G3 in the intermediate magnification state D23T: Distance between the second lens group G2 and the third lens group G3 at the telephoto end D34W: Distance between the third lens group G3 and the image-side lens group GR at the wide-angle end D34T: Distance between the third lens group G3 and the image-side lens group GR at the telephoto end fw: focal length of the entire lens system at the wide-angle end when shooting at infinity ft: focal length of the entire lens system when shooting at infinity at the telephoto end The intermediate state of magnification variation is defined as a state in which the focal length of the entire optical system is √(fw×ft) or close to it due to magnification variation. [Effects of the Invention]

[0011] According to the present invention, by appropriately setting the trajectory of each lens group during magnification variation, it is possible to provide a variable magnification optical system that has a relatively large aperture ratio and is compact, yet corrects various aberrations such as spherical aberration and field curvature over the entire variable magnification range. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of the variable magnification optical system of Example 1 at the wide-angle end when focused on infinity. [Figure 2] Longitudinal aberration diagram of the variable magnification optical system of Example 1 at the wide-angle end when focused on infinity [Figure 3] Longitudinal aberration diagram of the variable magnification optical system of Example 1 at an intermediate focal length when focused at infinity [Figure 4] Longitudinal aberration diagram of the variable magnification optical system of Example 1 at the telephoto end when focused on infinity [Figure 5] Transverse aberration diagram of the variable magnification optical system of Example 1 at the wide-angle end when focused on infinity [Figure 6]Transverse aberration diagram of the variable magnification optical system of Example 1 at an intermediate focal length when focused at infinity [Figure 7] Transverse aberration diagram of the variable magnification optical system of Example 1 at the telephoto end when focused on infinity [Figure 8] 10 is a cross-sectional view of the variable magnification optical system of Example 2 at the wide-angle end when focused on infinity. [Figure 9] Longitudinal aberration diagram of the variable magnification optical system of Example 2 at the wide-angle end when focused on infinity [Figure 10] Longitudinal aberration diagram of the variable magnification optical system of Example 2 at an intermediate focal length when focused at infinity [Figure 11] Longitudinal aberration diagram of the variable magnification optical system of Example 2 at the telephoto end when focused on infinity [Figure 12] Transverse aberration diagram of the variable magnification optical system of Example 2 at the wide-angle end when focused on infinity [Figure 13] Transverse aberration diagram of the variable magnification optical system of Example 2 at an intermediate focal length when focused at infinity [Figure 14] Transverse aberration diagram of the variable magnification optical system of Example 2 at the telephoto end when focused on infinity [Figure 15] 10 is a cross-sectional view of the variable magnification optical system of Example 3 at the wide-angle end when focused on infinity. [Figure 16] Longitudinal aberration diagram of the variable magnification optical system of Example 3 at the wide-angle end when focused on infinity [Figure 17] Longitudinal aberration diagram of the variable magnification optical system of Example 3 at an intermediate focal length when focused at infinity [Figure 18] Longitudinal aberration diagram of the variable magnification optical system of Example 3 at the telephoto end when focused on infinity [Figure 19] Transverse aberration diagram of the variable magnification optical system of Example 3 at the wide-angle end when focused on infinity [Figure 20] Transverse aberration diagram of the variable magnification optical system of Example 3 at an intermediate focal length when focused at infinity [Figure 21] Transverse aberration diagram of the variable magnification optical system of Example 3 at the telephoto end when focused on infinity [Figure 22] 10 is a cross-sectional view of the variable magnification optical system of Example 4 at the wide-angle end when focused on infinity. [Figure 23] Longitudinal aberration diagram of the variable magnification optical system of Example 4 at the wide-angle end when focused on infinity [Figure 24] Longitudinal aberration diagram of the variable magnification optical system of Example 4 at an intermediate focal length when focused at infinity [Figure 25] Longitudinal aberration diagram of the variable magnification optical system of Example 4 at the telephoto end when focused on infinity [Figure 26] Transverse aberration diagram of the variable magnification optical system of Example 4 at the wide-angle end when focused on infinity [Figure 27] Transverse aberration diagram of the variable magnification optical system of Example 4 at an intermediate focal length when focused at infinity [Figure 28] Transverse aberration diagram of the variable magnification optical system of Example 4 at the telephoto end when focused on infinity [Figure 29] 10 is a cross-sectional view of the variable magnification optical system of Example 5 at the wide-angle end when focused on infinity. [Figure 30] Longitudinal aberration diagram of the variable magnification optical system of Example 5 at the wide-angle end when focused on infinity [Figure 31] Longitudinal aberration diagram of the variable magnification optical system of Example 5 at an intermediate focal length when focused at infinity [Figure 32] Longitudinal aberration diagram of the variable magnification optical system of Example 5 at the telephoto end when focused on infinity [Figure 33] Transverse aberration diagram of the variable magnification optical system of Example 5 at the wide-angle end when focused on infinity [Figure 34] Transverse aberration diagram of the variable magnification optical system of Example 5 at an intermediate focal length when focused at infinity [Figure 35] Transverse aberration diagram of the variable magnification optical system of Example 5 at the telephoto end when focused on infinity [Figure 36] 10 is a cross-sectional view of the variable magnification optical system of Example 6 at the wide-angle end when focused on infinity. [Figure 37] Longitudinal aberration diagram of the variable magnification optical system of Example 6 at the wide-angle end when focused on infinity [Figure 38] Longitudinal aberration diagram of the variable magnification optical system of Example 6 at an intermediate focal length when focused at infinity [Figure 39] Longitudinal aberration diagram of the variable magnification optical system of Example 6 at the telephoto end when focused on infinity [Figure 40] Transverse aberration diagram of the variable magnification optical system of Example 6 at the wide-angle end when focused on infinity [Figure 41] Transverse aberration diagram of the variable magnification optical system of Example 6 at an intermediate focal length when focused at infinity [Figure 42] Transverse aberration diagram of the variable magnification optical system of Example 6 at the telephoto end when focused on infinity [Figure 43] 10 is a cross-sectional view of the variable magnification optical system of Example 7 at the wide-angle end when focused on infinity. [Figure 44] Longitudinal aberration diagram of the variable magnification optical system of Example 7 at the wide-angle end when focused on infinity [Figure 45] Longitudinal aberration diagram of the variable magnification optical system of Example 7 at an intermediate focal length when focused at infinity [Figure 46] Longitudinal aberration diagram of the variable magnification optical system of Example 7 at the telephoto end when focused on infinity [Figure 47] Transverse aberration diagram of the variable magnification optical system of Example 7 at the wide-angle end when focused on infinity [Figure 48] Transverse aberration diagram of the variable magnification optical system of Example 7 at an intermediate focal length when focused at infinity [Figure 49] Transverse aberration diagram of the variable magnification optical system of Example 7 at the telephoto end when focused on infinity DETAILED DESCRIPTION OF THE INVENTION

[0013] Examples of the optical system according to the present invention will be described in detail below. Note that the following description of the examples is an example of a variable magnification optical system according to the present invention, and the present invention is not limited to these examples within the scope of the gist of the present invention.

[0014] As can be seen from the lens construction diagrams shown in Figures 1, 8, 15, 22, 29, 36, and 43, the variable magnification optical system of the present invention is composed of, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and an image-side lens group GR, and when varying magnification from the wide-angle end to the telephoto end, the air space between the first lens group G1 and the second lens group G2 decreases, the air space between the second lens group G2 and the third lens group G3 changes, and the air space between the third lens group G3 and the image-side lens group GR increases.

[0015] The objective of the present invention is to provide a variable magnification optical system that has a relatively large aperture ratio and is compact, yet corrects for various aberrations, including field curvature, throughout the entire variable magnification range, and it is therefore important to appropriately set the trajectory of each lens group as the magnification changes.

[0016] In a variable magnification optical system, a method is known in which, from the object side, a group having negative refractive power, a group having positive refractive power, and a group having positive refractive power are arranged, and the spacing between the groups is changed to control the curvature of field in the intermediate zoom range while maintaining a wide angle of view at the wide-angle end. However, in the group arrangement of the present invention, if the spacing between the second lens group G2 and the third lens group G3 widens at the wide-angle end, the variable magnification function of the second lens group G2 is restricted, while if the spacing between the second lens group G2 and the third lens group G3 widens at the telephoto end, the variable magnification function of the third lens group G3 is restricted.

[0017] If the second lens group G2 and the third lens group G3 are aligned and made into the same lens group during magnification, the magnification function is not restricted and the diameter of the marginal ray beam incident on the third lens group G3 and the image-side lens group GR can be reduced. However, it becomes necessary to move the first lens group G1 significantly along the optical axis to reduce fluctuations in field curvature in the focal range during magnification. Since the first lens group G1 has a relatively large lens diameter and tends to make the lens barrel heavy, a large amount of movement during magnification requires a larger mechanism for supporting the lens, increasing the weight of the entire optical system. Furthermore, because the object side of the first lens group G1 is in contact with the outside air, significant movement also reduces the strength and dust- and moisture-resistant performance of the lens barrel.

[0018] Therefore, by setting the distance between the second lens group G2 and the third lens group G3 to be close to the minimum at the wide-angle end and the telephoto end and to a locus that widens at the intermediate position of the magnification, it is possible to suppress the change in field curvature while reducing the amount of movement of the first lens group G1, making it possible to make the lens compact and lightweight.

[0019] The variable magnification optical system of the present invention is further characterized by satisfying the following conditional expression: (1)-0.08 < (D23T-D23W) / (D12W-D12T) < 0.08 D12W: Distance between the first lens group G1 and the second lens group G2 at the wide-angle end D12T: Distance between the first lens group G1 and the second lens group G2 at the telephoto end D23W: Distance between the second lens group G2 and the third lens group G3 at the wide-angle end D23T: Distance between the second lens group G2 and the third lens group G3 at the telephoto end

[0020] Conditional formula (1) defines a preferable range for the ratio of the change in the distance between the first lens group G1 and the second lens group G2 to the change in the distance between the second lens group G2 and the third lens group G3 from the wide-angle end to the telephoto end.

[0021] If the lower limit of conditional expression (1) is exceeded and the distance between the second lens group G2 and the third lens group G3 at the wide-angle end becomes large, the magnification change function of the second lens group G2 is restricted, making it difficult to ensure a sufficient range of magnification change.

[0022] If the upper limit of conditional expression (1) is exceeded and the distance between the second lens group G2 and the third lens group G3 at the telephoto end becomes large, the diameter of the marginal light beam at the third lens group G3 and the image-plane-side lens group GR increases, making it difficult to reduce the size of the lens barrel.

[0023] Furthermore, by setting the lower limit of conditional expression (1) to -0.06, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (1) to 0.06, the effect of the present invention can be achieved more reliably.

[0024] The variable magnification optical system of the present invention is further characterized by satisfying the following conditional expression: (2)0.08 < (D23N-D23W) / (D12W-D12T) < 0.40 D23N: Distance between the second lens group G2 and the third lens group G3 in the intermediate magnification state fw: focal length of the entire lens system at the wide-angle end when shooting at infinity ft: focal length of the entire lens system when shooting at infinity at the telephoto end The intermediate state of magnification variation is defined as a state in which the focal length of the entire optical system is √(fw×ft) or close to it due to magnification variation.

[0025] Conditional expression (2) defines a preferable range for the distance between the second lens group G2 and the third lens group G3 in an intermediate state of magnification.

[0026] If the lower limit of conditional expression (2) is exceeded and the distance between the second lens group G2 and the third lens group G3 in the intermediate magnification range becomes narrow, it becomes difficult to suppress curvature of field near this magnification range.

[0027] If the upper limit of conditional expression (2) is exceeded and the distance between the second lens group G2 and the third lens group G3 in the intermediate magnification range becomes large, it becomes difficult to suppress chromatic aberration of magnification near this magnification range.

[0028] Furthermore, by setting the lower limit of conditional expression (2) to 0.10, the effects of the present invention can be more reliably achieved. By setting the upper limit of conditional expression (2) to 0.35, the effects of the present invention can be more reliably achieved. Furthermore, in order to reliably achieve the effects of the present invention, it is preferable to set the upper limit of conditional expression (2) to 0.30.

[0029] The variable magnification optical system of the present invention is further characterized by satisfying the following conditional expression: (3)0.08 < (D23N-D23T) / (D12W-D12T) < 0.40 D23N: Distance between the second lens group G2 and the third lens group G3 in the intermediate magnification state fw: focal length of the entire lens system at the wide-angle end when shooting at infinity ft: focal length of the entire lens system when shooting at infinity at the telephoto end The intermediate state of magnification variation is defined as a state in which the focal length of the entire optical system is √(fw×ft) or close to it due to magnification variation.

[0030] Conditional expression (3) defines a preferable range for the distance between the second lens group G2 and the third lens group G3 in an intermediate state of magnification.

[0031] If the lower limit of conditional expression (3) is exceeded and the distance between the second lens group G2 and the third lens group G3 in the intermediate magnification range becomes narrow, it becomes difficult to suppress spherical aberration near this magnification range.

[0032] If the upper limit of conditional expression (3) is exceeded and the distance between the second lens group G2 and the third lens group G3 in the intermediate magnification range becomes large, spherical aberration near this magnification range will be overcorrected and it will become difficult to suppress lateral chromatic aberration.

[0033] Furthermore, by setting the lower limit of conditional expression (3) to 0.10, the effects of the present invention can be achieved more reliably. By setting the upper limit of conditional expression (3) to 0.35, the effects of the present invention can be achieved more reliably. Furthermore, in order to reliably achieve the effects of the present invention, it is preferable to set the upper limit of conditional expression (3) to 0.30.

[0034] The variable magnification optical system of the present invention is further characterized by satisfying the following conditional expression: (4)0.50 < (D34T-D34W) / (D12W-D12T) < 2.00 D34W: Distance between the third lens group G3 and the image-side lens group GR at the wide-angle end D34T: Distance between the third lens group G3 and the image-side lens group GR at the telephoto end

[0035] Condition (4) defines a preferable range for the ratio of the change in the distance between the first lens group G1 and the second lens group G2 to the change in the distance between the third lens group G3 and the image-plane-side lens group GR from the wide-angle end to the telephoto end.

[0036] If the lower limit of conditional expression (4) is exceeded and the distance between the third lens group G3 and the image-plane-side lens group GR at the telephoto end becomes narrow, the magnification change function of the third lens group G3 is restricted, making it difficult to ensure a sufficient magnification change range.

[0037] If the upper limit of conditional expression (4) is exceeded and the distance between the third lens group G3 and the image-plane-side lens group GR at the telephoto end becomes large, the diameter of the off-axial light beam in the third lens group G3 and the group on its object side increases, making it difficult to make the lens barrel compact.

[0038] Furthermore, by setting the lower limit of conditional expression (4) to 0.70, the effects of the present invention can be achieved more reliably. In order to further ensure the effects of the present invention, it is preferable to set the lower limit of conditional expression (4) to 0.90. In addition, by setting the upper limit of conditional expression (4) to 1.80, the effects of the present invention can be achieved more reliably. In order to further ensure the effects of the present invention, it is preferable to set the upper limit of conditional expression (4) to 1.60.

[0039] It is also desirable that the variable magnification optical system of the present invention satisfy the following conditional expression: (5)-0.04 < (LTN-LTW) / LTW < 0.06 (6)-0.06 < (LTT-LTW) / LTW < 0.08 LTW: Total lens length at the wide-angle end LTN: Total lens length at intermediate magnification LTT: Total length of lens at telephoto end

[0040] If the lower or upper limit of condition (5) is exceeded and the overall lens length changes due to magnification, it becomes difficult to ensure the strength and dustproof / waterproof performance of the lens barrel.

[0041] If the lower or upper limit of conditional expression (6) is exceeded and the overall lens length changes due to magnification, it becomes difficult to ensure the strength and dust-proof and moisture-proof performance of the lens barrel.

[0042] Furthermore, by setting the lower limit of conditional expression (5) to -0.02, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (5) to 0.03, the effect of the present invention can be achieved more reliably.

[0043] Furthermore, by setting the lower limit of conditional expression (6) to -0.03, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (6) to 0.04, the effect of the present invention can be achieved more reliably.

[0044] In the variable magnification optical system of the present invention, it is desirable that the first lens group G1 remains stationary during magnification variation.

[0045] By keeping the first lens group G1 stationary during zooming, it becomes easier to ensure the strength and dust-proof and drip-proof performance of the lens barrel.

[0046] In the variable magnification optical system of the present invention, it is desirable that the first lens group G1 further includes one or more lenses having positive refractive power and two or more lenses having negative refractive power, and that the following conditional expression be satisfied: (7) 0.20 < ndPG1-ndNG1 < 0.45 ndPG1: average value of refractive index at the wavelength of the d-line of the lenses having positive refractive power arranged in the first lens group G1 ndNG1: average value of refractive index at the wavelength of the d-line of the lens having negative refractive power arranged in the first lens group G1

[0047] If the lower limit of conditional expression (7) is exceeded and the difference in refractive index between the lens having positive refractive power and the lens having negative refractive power in the first lens group G1 becomes small, it becomes difficult to suppress curvature of field.

[0048] If the upper limit of conditional expression (7) is exceeded and the difference in refractive index between the lens element having positive refractive power and the lens element having negative refractive power in the first lens group G1 becomes large, the range of glass materials that can be used is limited, and it becomes difficult to maintain a wide angle of view at the wide-angle end while suppressing distortion.

[0049] Furthermore, by setting the lower limit of conditional expression (7) to 0.25, the effect of the present invention can be more reliably achieved, and by setting the upper limit of conditional expression (7) to 0.40, the effect of the present invention can be more reliably achieved.

[0050] In the variable magnification optical system of the present invention, it is desirable that the second lens group G2 further includes one or more lenses having positive refractive power and one or more lenses having negative refractive power, and that the following conditional expression be satisfied: (8) dPgPG2-dPgNG2 > 0.010 dPgPG2: The average value of the deviation of the partial dispersion ratio for the g-line of the lens having positive refractive power arranged in the second lens group G2 dPgNG2: Average value of deviation of partial dispersion ratio for g-line of lens having negative refractive power arranged in second lens group G2 However, the deviation dPgF of the partial dispersion ratio for the g-line is given by θgF for each lens, and vd for the Abbe number at the d-line. dPgF=θgF-(0.648285-0.00180123×vd) is calculated as

[0051] If the lower limit of conditional expression (8) is exceeded and the difference in partial dispersion ratio for the g-line between the lens having positive refractive power and the lens having negative refractive power in the second lens group G2 becomes small, it becomes difficult to suppress axial chromatic aberration and chromatic aberration of magnification on the telephoto side.

[0052] Furthermore, by setting the lower limit of conditional expression (8) to 0.015, the effects of the present invention can be achieved more reliably.

[0053] In the variable magnification optical system of the present invention, it is desirable that the image-side lens group GR further includes one or more lenses having positive refractive power and one or more lenses having negative refractive power, and that the following conditional expression be satisfied: (9) dPgPGR-dPgNGR > 0.010 dPgPGR: Average value of deviation of partial dispersion ratio for g-line of lenses with positive refractive power arranged in the image-side lens group GR dPgNGR: Average value of deviation of partial dispersion ratio for g-line of lenses with negative refractive power arranged in the image-side lens group GR As with conditional formula (8), the deviation dPgF of the partial dispersion ratio for the g-line is given by θgF for each lens, and vd for the Abbe number at the d-line. dPgF=θgF-(0.648285-0.00180123×vd) is calculated as

[0054] If the lower limit of conditional expression (9) is exceeded and the difference in partial dispersion ratio for the g-line between the lens element having positive refractive power and the lens element having negative refractive power in the image-plane-side lens group GR becomes small, it becomes difficult to suppress lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end.

[0055] Furthermore, by setting the lower limit of conditional expression (9) to 0.015, the effects of the present invention can be achieved more reliably.

[0056] Furthermore, it is desirable that the variable magnification optical system of the present invention further satisfies the following conditional expression: (10)-0.60 < fw / f1 < -0.30 (11) 0.20 < ft / f2 < 0.60 (12) 0.40 < ft / f3 < 0.80 fw: focal length of the entire lens system at the wide-angle end when shooting at infinity ft: focal length of the entire lens system when shooting at infinity at the telephoto end f1: focal length of the first lens group G1 f2: Focal length of the second lens group G2 f3: Focal length of the third lens group G3

[0057] If the lower limit of conditional expression (10) is exceeded and the negative refractive power of the first lens group G1 becomes too strong, the marginal light beam becomes thicker, making it difficult to reduce the diameter of the lenses in the second lens group G2 and onward.

[0058] If the upper limit of conditional expression (10) is exceeded and the negative refractive power of the first lens group G1 becomes weak, it becomes difficult to maintain a wide angle of view at the wide-angle end.

[0059] Furthermore, by setting the lower limit of conditional expression (10) to -0.55, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (10) to -0.35, the effect of the present invention can be achieved more reliably.

[0060] If the lower limit of conditional expression (11) is exceeded and the positive refractive power of the second lens group G2 becomes weak, the marginal light beam becomes thicker, making it difficult to reduce the diameter of the lenses after the third lens group G3.

[0061] If the upper limit of conditional expression (11) is exceeded and the positive refractive power of the second lens group G2 becomes strong, it becomes difficult to select a glass material for the lenses in the second lens group G2 that satisfies conditional expression (8) while suppressing spherical aberration and coma aberration.

[0062] Furthermore, by setting the lower limit of conditional expression (11) to 0.25, the effect of the present invention can be more reliably achieved, and by setting the upper limit of conditional expression (11) to 0.55, the effect of the present invention can be more reliably achieved.

[0063] If the lower limit of conditional expression (12) is exceeded and the positive refractive power of the third lens group G3 becomes weak, it becomes difficult to ensure sufficient zooming function when changing from the wide-angle end to the telephoto end.

[0064] If the upper limit of conditional expression (12) is exceeded and the positive refractive power of the third lens group G3 becomes too strong, it becomes difficult to suppress spherical aberration and coma.

[0065] Furthermore, by setting the lower limit of conditional expression (12) to 0.45, the effect of the present invention can be more reliably achieved, and by setting the upper limit of conditional expression (12) to 0.75, the effect of the present invention can be more reliably achieved.

[0066] In the variable magnification optical system of the present invention, it is desirable that the image-plane-side lens group GR further comprises, from the object side, a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power.

[0067] By using such an arrangement, it becomes possible to appropriately control the fluctuations of spherical aberration and astigmatism.

[0068] Furthermore, it is desirable that the variable magnification optical system of the present invention further satisfies the following conditional expression: (13)-1.40 < ft / f4 < -0.70 f4: Focal length of the fourth lens group G4

[0069] If the lower limit of conditional expression (13) is exceeded and the negative refractive power of the fourth lens group G4 becomes too strong, the marginal light beam becomes too thick, making it difficult to reduce the diameter of the lenses in the fifth lens group G5 and onwards.

[0070] If the upper limit of conditional expression (13) is exceeded and the negative refractive power of the fourth lens group G4 becomes weak, it becomes difficult to suppress fluctuations in spherical aberration.

[0071] Furthermore, by setting the lower limit of conditional expression (13) to -1.30, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (13) to -0.80, the effect of the present invention can be achieved more reliably.

[0072] Furthermore, it is desirable that the variable magnification optical system of the present invention further satisfies the following conditional expression: (14) 1.75 < ft / fw < 3.50

[0073] If the lower limit of conditional expression (14) is exceeded and the zoom ratio of the optical system becomes small, it becomes difficult to obtain the convenience of a variable magnification optical system, and if the upper limit of conditional expression (14) is exceeded and the zoom ratio of the optical system becomes large, it becomes difficult to achieve compactness while maintaining high imaging performance.

[0074] Furthermore, by setting the lower limit of conditional expression (14) to 2.00, the effect of the present invention can be achieved more reliably. Furthermore, by setting the upper limit of conditional expression (14) to 3.00, the effect of the present invention can be achieved more reliably.

[0075] Furthermore, it is desirable that the variable magnification optical system of the present invention further satisfies the following conditional expression: (15) 1.40 ≦ Fnot ≦ 2.80 Fnot: F-number of the entire lens system when shooting at infinity at the telephoto end

[0076] If the lower limit of conditional expression (15) is exceeded and the F-number of the optical system becomes too large, it becomes difficult to achieve compactness while maintaining high imaging performance.If the upper limit of conditional expression (15) is exceeded and the F-number becomes too small, it becomes difficult to take advantage of large bokeh or to use a short shutter speed in dark places.

[0077] Furthermore, by setting the lower limit of conditional expression (15) to 1.60, the effect of the present invention can be more reliably achieved, and by setting the upper limit of conditional expression (15) to 2.40, the effect of the present invention can be more reliably achieved.

[0078] Next, lens configurations, numerical examples, and corresponding values ​​of conditional expressions of examples of the variable magnification optical system of the present invention will be described. Note that in the following description, the lens configurations will be described in order from the object side to the image plane side.

[0079] In the [Surface Data] section, the surface number is the lens surface or aperture stop number counted from the object side, r is the radius of curvature of each lens surface, d is the spacing between each lens surface, nd is the refractive index for the d-line (wavelength 587.56 nm), vd is the Abbe number for the d-line, and θgF is the partial dispersion ratio between the g-line (wavelength 435.84 nm) and the F-line (wavelength 486.13 nm).

[0080] An asterisk (*) next to a surface number indicates that the lens surface is aspherical, and BF represents the back focal length.

[0081] The (diaphragm) next to the surface number indicates that an aperture diaphragm is located at that position. The radius of curvature for the plane or aperture diaphragm is marked as ∞ (infinity).

[0082] [Aspherical Surface Data] shows the values ​​of each coefficient that determines the aspherical shape of lens surfaces marked with an * in [Surface Data]. The shape of an aspherical surface is expressed by the following equation. In the equation below, y represents the displacement from the optical axis in a direction perpendicular to the optical axis, z represents the displacement (sag) from the intersection of the aspherical surface and the optical axis in the direction of the optical axis, r represents the radius of curvature of the reference sphere, and K is the Conic coefficient. Furthermore, when the aspherical coefficients of the 4th, 6th, 8th, 10th, 12th, and 14th orders are represented by A4, A6, A8, A10, A12, and A14, respectively, the coordinates of the aspherical surface are expressed by the following equation.

[0083] TIFF2026024127000002.tif19123

[0084] [Various Data] shows values ​​such as zoom ratio and focal length for each focal length state.

[0085] [Variable Distance Data] shows the variable distance and BF values ​​for each focal length state.

[0086] [Lens Group Data] shows the surface number of each lens group closest to the object and the composite focal length of the entire group.

[0087] In the aberration diagrams corresponding to the respective examples, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and meridional image surface, respectively.

[0088] In the following specification values, the focal length f, radius of curvature r, lens surface spacing d, and other length units are given in millimeters (mm) unless otherwise specified; however, this is not a limitation, as optical systems can achieve equivalent optical performance with proportional magnification and proportional reduction. [Example]

[0089] FIG. 1 is a diagram showing the configuration of an optical system according to a first embodiment of the present invention.

[0090] The optical system of Example 1 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S moves integrally with the fourth lens group G4 during magnification variation.

[0091] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0092] The second lens group G2 is composed solely of a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image surface side.

[0093] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0094] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0095] The fifth lens group G5 is composed of, in order from the object side, a cemented lens consisting of a biconcave lens and a biconvex lens, a biconvex lens, and a positive meniscus lens whose both surfaces have predetermined aspherical shapes and whose convex surface faces the object side.

[0096] The sixth lens group G6 is composed solely of a negative meniscus lens with its convex surface facing the object side, and moves entirely toward the image plane during focusing from an infinity object distance to a close distance.

[0097] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0098] Furthermore, in the variable magnification optical system of Example 1, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0099] In the variable magnification optical system of Example 1, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0100] Next, the specifications of the optical system according to the first embodiment are shown below. Numerical Example 1 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 250.0000 2.0027 1.59271 66.97 0.5367 2 27.8483 5.9106 3* 75.5339 1.7000 1.55352 71.72 0.5398 4* 43.9336 8.9578 5 -42.5013 1.2000 1.48749 70.44 0.5306 6 59.3792 4.8124 1.85033 42.70 0.5646 7 -158.0782 (d7) 8 73.9893 7.8404 1.55032 75.50 0.5401 9 -38.4074 0.9000 1.77047 29.74 0.5951 10 -71.2235 (d10) 11 69.5442 0.9000 1.75211 25.05 0.6192 12 39.4005 6.0497 1.75500 52.32 0.5473 13 -303.0102 (d13) 14 (Aperture) ∞ 3.4674 15 -31.4322 0.9500 1.78590 43.94 0.5612 16 49.4614 2.2536 1.98612 16.48 0.6656 17 258.2249 (d17) 18 -410.5686 0.9000 1.73037 32.23 0.5899 19 26.6348 6.4880 1.59282 68.62 0.5440 20 -44.4800 0.1500 21 31.2840 5.5107 1.59282 68.62 0.5440 22 -57.9617 0.2500 23* 35.7978 2.7669 1.59271 66.97 0.5367 24* 234.5415 (d24) 25 46.4631 0.9000 1.74330 49.22 0.5495 26 17.9200 (d26) 27* 60.4900 3.8719 1.80610 40.73 0.5694 28 -80.4564 0.9000 1.85451 25.15 0.6103 29 80.4564 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 23rd page 24th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 8.81137E-06 -2.07372E-06 6.10616E-06 -8.60792E-06 3.85958E-06 A6 -9.35247E-09 7.46142E-09 6.61601E-09 1.99952E-09 1.95216E-08 A8 3.56200E-12 -1.62322E-11 -4.17607E-11 -4.94951E-11 -7.83598E-11 A10 9.76737E-15 9.72804E-15 5.07229E-14 -7.59311E-14 1.91464E-13 A12 -1.41083E-17 0.00000E+00 0.00000E+00 5.27607E-16 0.00000E+00 A14 6.28920E-21 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 27 sides K 0.00000 A4 1.05308E-06 A6 5.18117E-08 A8 -4.36191E-10 A10 2.64638E-12 A12 -5.67644E-15 A14 0.00000E+00 [Various data] Zoom ratio 2.21 Wide-angle Mid-range Telephoto Focal length 17.55 26.06 38.70 F-number 1.86 1.86 1.86 Full angle of view 2ω 83.28 56.14 38.54 Image height Y 14.20 14.20 14.20 Lens length 133.60 133.60 133.60 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 24.2001 10.3101 1.3704 d10 1.0967 4.7167 1.0966 d13 1.7600 13.8950 29.4811 d17 11.0343 7.0293 1.6434 d24 3.5756 2.6096 1.6000 d26 6.5786 7.5446 8.5541 BF 16.6727 18.8127 21.1723 [Lens group data] Group Starting plane Focal length G1 1 -41.68 G2 8 81.16 G3 11 75.35 G4 14 -40.22 G5 18 20.37 G6 25 -39.78 G7 27 401.59 [Example]

[0101] FIG. 8 is a diagram showing the configuration of an optical system according to a second embodiment of the present invention.

[0102] The optical system of Example 2 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S moves integrally with the fourth lens group G4 during magnification variation.

[0103] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0104] The second lens group G2 is composed solely of a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image surface side.

[0105] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0106] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0107] The fifth lens group G5 is composed of, in order from the object side, a cemented lens consisting of a biconcave lens and a biconvex lens, a biconvex lens, and a positive meniscus lens whose both surfaces have predetermined aspherical shapes and whose convex surface faces the object side.

[0108] The sixth lens group G6 is composed solely of a negative meniscus lens with its convex surface facing the object side, and moves entirely toward the image plane during focusing from an infinity object distance to a close distance.

[0109] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0110] Furthermore, in the variable magnification optical system of Example 2, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0111] In the variable magnification optical system of Example 2, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0112] Next, the specifications of the optical system according to the second embodiment are shown below. Numerical Example 2 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 250.0000 2.0000 1.59271 66.97 0.5367 2 28.0986 5.9974 3* 79.6790 1.7000 1.55352 71.72 0.5398 4* 42.3231 8.9421 5 -44.2746 1.2000 1.48749 70.44 0.5306 6 62.2565 5.0259 1.85033 42.70 0.5646 7 -132.4181 (d7) 8 71.3997 7.9567 1.57144 71.61 0.5419 9 -38.7392 0.9000 1.73037 32.23 0.5899 10 -88.3123 (d10) 11 57.1124 0.9000 1.68430 26.81 0.6232 12 38.5040 6.5166 1.59282 68.62 0.5440 13 -169.7744 (d13) 14 (Aperture) ∞ 3.4915 15 -30.7261 0.9500 1.78590 43.94 0.5612 16 52.1805 2.2231 1.98612 16.48 0.6656 17 317.2241 (d17) 18 -250.4292 0.9000 1.73037 32.23 0.5899 19 26.9764 6.5142 1.59282 68.62 0.5440 20 -41.9747 0.1500 21 31.3561 5.4603 1.59282 68.62 0.5440 22 -58.8165 0.2500 23* 33.3228 3.0755 1.59271 66.97 0.5367 24* 321.7339 (d24) 25 52.1821 0.9000 1.74330 49.22 0.5495 26 17.7596 (d26) 27* 63.5310 3.7356 1.77250 49.50 0.5519 28 -78.8320 0.9000 1.77047 29.74 0.5951 29 78.8320 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 23rd page 24th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 7.26691E-06 -6.24828E-07 5.81787E-06 -8.59838E-06 3.80591E-06 A6 -7.22521E-09 6.26382E-09 5.39580E-09 -1.12781E-08 2.43011E-09 A8 -4.06461E-13 -2.14124E-11 -4.71268E-11 -1.16085E-11 -2.25411E-12 A10 1.61641E-14 1.59496E-14 5.37658E-14 -1.18479E-13 8.99556E-14 A12 -2.07944E-17 0.00000E+00 0.00000E+00 6.31297E-16 0.00000E+00 A14 9.19755E-21 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 27 sides K 0.00000 A4 5.05265E-07 A6 5.94289E-08 A8 -5.47652E-10 A10 3.60505E-12 A12 -8.28823E-15 A14 0.00000E+00 [Various data] Zoom ratio 2.21 Wide-angle Mid-range Telephoto Focal length 17.55 26.06 38.70 F-number 1.86 1.86 1.86 Full angle of view 2ω 83.27 56.11 38.54 Image height Y 14.20 14.20 14.20 Lens length 133.60 133.60 133.60 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 24.4525 10.1532 1.2336 d10 1.0107 4.7033 1.0000 d13 1.5000 14.5085 29.5150 d17 10.4987 6.5321 1.2531 d24 3.5725 2.8431 1.6000 d26 6.2091 6.9385 8.1816 BF 16.6677 18.2325 21.1280 [Lens group data] Group Starting plane Focal length G1 1 -43.52 G2 8 83.44 G3 11 77.20 G4 14 -40.14 G5 18 19.71 G6 25 -36.63 G7 27 367.38 [Example]

[0113] FIG. 15 is a diagram showing the configuration of an optical system according to a third embodiment of the present invention.

[0114] The optical system of Example 3 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S moves integrally with the fourth lens group G4 during magnification variation.

[0115] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0116] The second lens group G2 is composed of a cemented lens made up of a biconvex lens and a biconcave lens, and a biconvex lens.

[0117] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0118] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0119] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconcave lens and a biconvex lens, a biconvex lens, and a biconvex lens whose both surfaces have predetermined aspherical shapes and whose convex surface faces the object side.

[0120] The sixth lens group G6 is composed solely of a negative meniscus lens with its convex surface facing the object side, and moves entirely toward the image plane during focusing from an infinity object distance to a close distance.

[0121] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0122] Furthermore, in the variable magnification optical system of Example 3, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0123] In the variable magnification optical system of Example 3, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0124] Next, the specifications of the optical system according to the third embodiment are shown below. Numerical Example 3 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 250.0000 2.0024 1.59271 66.97 0.5367 2 28.3681 6.1839 3* 88.8389 1.7000 1.55352 71.72 0.5398 4* 42.9753 8.2631 5 -51.9299 1.2000 1.48749 70.44 0.5306 6 55.8392 4.9041 1.88300 40.81 0.5656 7 -218.7120 (d7) 8 97.0199 4.8364 1.55032 75.50 0.5401 9 -81.1509 0.9000 1.77047 29.74 0.5951 10 1096.3011 0.1500 11 135.4524 4.0554 1.55032 75.50 0.5401 12 -107.0918 (d12) 13 62.5660 0.9000 1.80809 22.76 0.6287 14 39.1804 6.0244 1.75500 52.32 0.5473 15 -339.3229 (d15) 16 (Aperture) ∞ 3.4363 17 -31.4738 0.9500 1.78590 43.94 0.5612 18 48.3598 2.2714 1.98612 16.48 0.6656 19 262.8369 (d19) 20 -279.2338 0.9000 1.73037 32.23 0.5899 21 27.1590 6.1753 1.59282 68.62 0.5440 22 -49.3988 0.1500 23 34.7926 5.2807 1.59282 68.62 0.5440 24 -56.4441 0.2500 25* 33.2854 3.5428 1.59271 66.97 0.5367 26* -1419.9085 (d26) 27 47.6860 0.9000 1.74330 49.22 0.5495 28 17.8501 (d28) 29* 64.2381 3.6815 1.82080 42.71 0.5643 30 -84.0859 0.9000 1.85451 25.15 0.6103 31 84.0859 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 25th page 26th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 6.31297E-06 6.53481E-07 6.33956E-06 -8.05304E-06 3.80378E-06 A6 -5.83453E-09 1.44395E-09 7.47935E-10 -5.73130E-09 2.90012E-09 A8 -1.74364E-12 -1.40687E-11 -3.75063E-11 -7.77939E-11 -6.34632E-11 A10 1.68817E-14 1.22544E-14 4.94385E-14 1.71745E-13 2.45809E-13 A12 -2.09273E-17 0.00000E+00 0.00000E+00 2.07293E-16 0.00000E+00 A14 9.13022E-21 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 29 sides K 0.00000 A4 4.41208E-07 A6 4.71040E-08 A8 -3.91613E-10 A10 2.51575E-12 A12 -5.53043E-15 A14 0.00000E+00 [Various data] Zoom ratio 2.21 Wide-angle Mid-range Telephoto Focal length 17.55 26.06 38.70 F-number 1.86 1.86 1.86 Full angle of view 2ω 83.28 56.19 38.54 Image height Y 14.20 14.20 14.20 Lens total length 134.80 134.80 134.80 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 24.2268 10.2456 1.2000 d12 1.5368 4.8568 1.5401 d15 1.8159 14.5431 30.0459 d19 10.8884 6.8733 1.3666 d26 3.7287 2.7156 1.6000 d28 6.4191 7.4321 8.5478 BF 16.6266 18.5758 20.9419 [Lens group data] Group Starting plane Focal length G1 1 -43.40 G2 8 88.85 G3 13 73.04 G4 16 -40.54 G5 20 20.19 G6 27 -38.88 G7 29 392.42 [Example]

[0125] FIG. 22 is a diagram showing the configuration of an optical system according to a fourth embodiment of the present invention.

[0126] The optical system of Example 4 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S moves integrally with the fourth lens group G4 during magnification variation.

[0127] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0128] The second lens group G2 is composed solely of a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image surface side.

[0129] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0130] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0131] The fifth lens group G5 is composed of, in order from the object side, a cemented lens made up of a biconcave lens and a biconvex lens, a biconvex lens, and a biconvex lens having predetermined aspherical shapes on both sides.

[0132] The sixth lens group G6 is composed solely of a cemented lens consisting of a positive meniscus lens with its convex surface facing the object side and a negative meniscus lens with its convex surface facing the object side, and the entire sixth lens group G6 moves toward the image plane during focusing from an infinity object distance to a close distance.

[0133] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0134] Furthermore, in the variable magnification optical system of Example 4, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0135] In the variable magnification optical system of Example 4, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0136] Next, the specifications of the optical system according to Example 4 are shown below. Numerical Example 4 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 500.0000 3.0410 1.59201 67.02 0.5358 2 37.1039 9.2482 3* 65.7351 2.0000 1.55332 71.69 0.5404 4* 45.0196 13.9075 5 -59.7341 1.5000 1.48749 70.44 0.5306 6 90.6103 7.2805 1.85033 42.70 0.5646 7 -158.4287 (d7) 8 113.8185 10.3255 1.57144 71.61 0.5419 9 -51.6441 1.0000 1.77047 29.74 0.5951 10 -158.0772 (d10) 11 79.9330 1.0000 1.75211 25.05 0.6192 12 62.8248 8.8988 1.59282 68.62 0.5440 13 -118.6927 (d13) 14 (Aperture) ∞ 5.3772 15 -40.3471 1.0000 1.77250 49.63 0.5504 16 79.5143 3.2109 1.98612 16.48 0.6656 17 458.9755 (d17) 18 -686.3201 0.9000 1.77047 29.74 0.5951 19 42.4979 8.0533 1.55032 75.50 0.5401 20 -73.2713 0.2250 21 51.2676 8.3088 1.59282 68.62 0.5440 22 -64.9895 0.2250 23* 59.0872 4.3507 1.59201 67.02 0.5358 24* -209.9135 (d24) 25 62.5397 3.1293 1.98612 16.48 0.6656 26 123.9355 0.9000 1.80610 40.73 0.5672 27 25.5511 (d27) 28* 70.4488 9.2933 1.77250 49.50 0.5519 29 -35.5253 1.0000 1.85451 25.15 0.6103 30 91.9834 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 23rd page 24th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 3.48286E-06 -4.20437E-06 -1.55795E-06 -3.63934E-06 1.42269E-06 A6 -1.63713E-09 -1.89212E-09 -2.02736E-09 -1.32663E-09 -3.14116E-10 A8 5.84000E-13 6.01256E-12 4.56248E-12 -2.25526E-12 -4.20361E-12 A10 1.07583E-16 -2.92652E-15 -1.24437E-15 -7.14925E-15 1.07396E-14 A12 -2.05468E-19 0.00000E+00 0.00000E+00 2.35051E-17 0.00000E+00 A14 6.55839E-23 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 28 sides K 0.00000 A4 1.47923E-06 A6 6.70199E-09 A8 -2.86956E-11 A10 9.67934E-14 A12 -1.03618E-16 A14 0.00000E+00 [Various data] Zoom ratio 2.05 Wide-angle Mid-range Telephoto Focal length 23.69 33.90 48.50 F-number 1.86 1.86 1.86 Full angle of view 2ω 90.19 64.73 46.05 Image height Y 21.63 21.63 21.63 Lens total length 185.00 185.00 185.00 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 30.7940 14.3869 1.5000 d10 1.4494 4.8874 1.2000 d13 1.6433 15.4572 34.4962 d17 12.6465 7.5533 2.4807 d24 5.3911 2.9749 2.0000 d27 7.1918 9.6080 10.5830 BF 21.7090 25.9573 28.5652 [Lens group data] Group Starting plane Focal length G1 1 -59.92 G2 8 166.57 G3 11 85.74 G4 14 -53.59 G5 18 29.20 G6 25 -61.78 G7 28 12794.38 [Example]

[0137] FIG. 29 is a diagram showing the configuration of an optical system according to a fifth embodiment of the present invention.

[0138] The optical system of Example 5 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S moves integrally with the fourth lens group G4 during magnification variation.

[0139] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0140] The second lens group G2 is composed solely of a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image surface side.

[0141] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0142] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a biconvex lens.

[0143] The fifth lens group G5 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens with its convex surface facing the object side and a biconvex lens, a biconvex lens, and a biconvex lens with both surfaces having a predetermined aspherical shape.

[0144] The sixth lens group G6 is composed solely of a negative meniscus lens element with a convex surface facing the object side and having a predetermined aspherical shape on both sides, and the entire sixth lens group G6 moves toward the image plane during focusing from an infinity object distance to a close distance.

[0145] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0146] Furthermore, in the variable magnification optical system of Example 5, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0147] In the variable magnification optical system of Example 5, when the magnification is changed from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0148] Next, the specifications of the optical system according to the fifth embodiment are shown below. Numerical Example 5 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 250.0000 2.0245 1.59271 66.97 0.5367 2 29.3085 5.9594 3* 79.7909 1.7000 1.55352 71.72 0.5398 4* 43.4138 8.6915 5 -55.0609 1.2000 1.48749 70.44 0.5306 6 50.3828 4.9573 1.85033 42.70 0.5646 7 -501.2275 (d7) 8 125.6707 7.2851 1.57144 71.61 0.5419 9 -34.9478 0.9000 1.77047 29.74 0.5951 10 -68.3843 (d10) 11 59.1788 0.9000 1.80809 22.76 0.6287 12 40.1403 6.2590 1.75500 52.32 0.5473 13 -205.5648 (d13) 14 (Aperture) ∞ 3.3947 15 -30.7802 0.9500 1.88300 40.81 0.5656 16 49.0857 2.4791 1.98612 16.48 0.6656 17 -8729.0655 (d17) 18 968.3922 0.9000 1.78880 28.43 0.6009 19 28.0850 6.2315 1.59282 68.62 0.5440 20 -45.6374 0.1500 21 36.7723 5.2950 1.59282 68.62 0.5440 22 -55.1086 0.2500 23* 34.7999 3.6104 1.59271 66.97 0.5367 24* -428.5708 (d24) 25* 53.7024 0.9000 1.69350 53.20 0.5467 26* 16.1945 (d26) 27* 49.5505 3.1653 1.72903 54.04 0.5447 28 -2028.2832 0.9000 1.85451 25.15 0.6103 29 70.5138 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 23rd page 24th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 4.47055E-06 6.52127E-06 1.07524E-05 -6.22097E-06 1.02264E-05 A6 -4.26254E-10 -2.18979E-08 -2.01293E-08 -6.15023E-08 -1.02559E-07 A8 -7.99807E-12 2.23821E-11 5.01199E-12 2.95996E-10 5.72026E-10 A10 1.78158E-14 -8.51543E-15 1.27037E-14 -3.93348E-13 -9.47038E-13 A12 -1.66389E-17 0.00000E+00 0.00000E+00 -1.08960E-16 0.00000E+00 A14 6.17964E-21 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 Page 25 Page 26 Page 27 K 0.00000 0.00000 0.00000 A4 1.22818E-05 6.17901E-06 4.01177E-06 A6 -1.60748E-07 -1.48795E-07 4.17665E-08 A8 7.38505E-10 5.00972E-10 -4.41285E-10 A10 -1.04189E-12 -8.59510E-13 3.37838E-12 A12 0.00000E+00 0.00000E+00 -8.30229E-15 A14 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.63 Wide-angle Mid-range Telephoto Focal length 16.55 26.83 43.50 F-number 2.06 2.06 2.06 Full angle of view 2ω 86.98 54.20 34.56 Image height Y 14.20 14.20 14.20 Lens total length 136.00 136.00 136.00 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 27.3034 9.5005 1.2000 d10 1.0051 7.0982 1.0000 d13 1.5000 15.7737 31.2158 d17 11.9908 6.9263 0.7272 d24 4.5046 3.5277 1.6000 d26 5.4813 6.4582 8.3859 BF 16.1120 18.6126 23.7683 [Lens group data] Group Starting plane Focal length G1 1 -41.83 G2 8 99.93 G3 11 63.18 G4 14 -37.82 G5 18 19.66 G6 25 -33.77 G7 27 339.33 [Example]

[0149] FIG. 36 is a diagram showing the configuration of an optical system according to a sixth embodiment of the present invention.

[0150] The optical system of Example 6 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, and a sixth lens group G6 with negative refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and moves integrally with the fourth lens group G4 during magnification variation.

[0151] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with its convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0152] The second lens group G2 is composed of a biconvex lens having a predetermined aspherical shape on both sides, and a negative meniscus lens with its convex surface facing the image surface side.

[0153] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0154] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0155] The fifth lens group G5 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens with its convex surface facing the object side and a biconvex lens, a biconvex lens, and a biconvex lens with predetermined aspherical surfaces on both sides. The fifth lens group G5 moves as a whole toward the object side during focusing from an infinity object distance to a close distance.

[0156] The sixth lens group G6 is composed of, in order from the object side, a cemented lens consisting of a positive meniscus lens with its convex surface facing the object side and a negative meniscus lens with its convex surface facing the object side, and a biconcave lens having a predetermined aspherical shape on both sides.

[0157] Furthermore, in the variable magnification optical system of Example 6, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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, and the distance between the sixth lens group G6 and the image plane increases.

[0158] In the variable magnification optical system of Example 6, when the magnification is changed from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the sixth lens group G6 each move relative to the image plane.

[0159] Next, the specifications of the optical system according to Example 6 are shown below. Numerical Example 6 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 103.7010 2.0000 1.69350 53.20 0.5467 2* 22.9882 9.8673 3 -200.0000 1.3300 1.43700 95.10 0.5336 4 31.3342 4.5273 1.85451 25.15 0.6103 5 59.9759 (d5) 6* 62.3752 6.5089 1.55332 71.69 0.5404 7* -48.6789 0.7545 8 -40.1587 0.9000 1.77047 29.74 0.5951 9 -84.4685 (d9) 10 59.7543 0.9000 1.85451 25.15 0.6103 11 31.0637 8.2482 1.72916 54.67 0.5453 12 -92.1898 (d12) 13 (Aperture) ∞ 3.0696 14 -40.0833 0.9500 1.83400 37.34 0.5790 15 45.4198 2.5009 1.98612 16.48 0.6656 16 190.2359 (d16) 17 57.0815 0.9000 1.85451 25.15 0.6103 18 31.7140 4.4777 1.48071 85.29 0.5362 19 -130.1923 0.1500 20 35.1735 5.5385 1.55032 75.50 0.5401 21 -75.8961 0.1500 22* 37.8578 4.5896 1.55332 71.69 0.5404 23* -80.5700 (d23) 24 50.2507 2.0923 2.00069 25.46 0.6136 25 77.2723 0.9000 1.62205 41.08 0.5690 26 17.2780 4.3945 27* -687.6936 1.1576 1.68893 31.16 0.6038 28* 92.8435 (BF) Image plane ∞ [Aspherical data] 1st floor 2nd floor 6th floor 7th floor 22nd floor K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 1.38184E-06 -2.47952E-06 -2.47854E-06 -1.52958E-06 -1.02375E-05 A6 -1.37202E-08 -2.08490E-08 1.07213E-09 1.59528E-09 -1.51606E-08 A8 3.49324E-11 -5.96343E-12 -5.26923E-12 -5.20292E-12 -8.46224E-11 A10 -4.29829E-14 6.55077E-14 0.00000E+00 0.00000E+00 6.11902E-13 A12 2.17686E-17 -1.77729E-16 0.00000E+00 0.00000E+00 -1.13199E-15 23rd page 27th page 28th page K 0.00000 0.00000 0.00000 A4 9.67871E-06 -1.16170E-05 -1.11984E-05 A6 -4.52747E-08 5.98165E-08 6.36589E-08 A8 1.71230E-10 -5.10795E-10 -6.08054E-10 A10 -2.39676E-13 1.61285E-12 1.55909E-12 A12 0.00000E+00 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.22 Wide-angle Mid-range Telephoto Focal length 17.51 ​​26.07 38.80 F-number 1.86 1.86 1.86 Full angle of view 2ω 83.30 56.82 38.45 Image height Y 14.20 14.20 14.20 Lens total length 132.00 132.00 132.00 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d5 27.3091 14.3706 6.2365 d9 2.2963 7.1073 1.4000 d12 1.6132 12.7162 30.2082 d16 15.8523 9.7321 4.6975 d23 2.7485 1.5000 1.5000 BF 16.2735 20.6669 22.0508 [Lens group data] Group Starting plane Focal length G1 1 -36.52 G2 6 97.39 G3 10 56.31 G4 13 -43.91 G5 17 21.17 G6 24 -34.66 [Example]

[0160] FIG. 43 is a diagram showing the configuration of an optical system according to a seventh embodiment of the present invention.

[0161] The optical system of Example 7 is composed of, from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with positive refractive power, and an image-side lens group GR. The image-side lens group GR is composed of, from the object side, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with positive refractive power. An aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and moves integrally with the fourth lens group G4 during magnification variation.

[0162] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface with a predetermined aspherical shape facing the object side, a negative meniscus lens having a predetermined aspherical shape on both sides with a convex surface facing the object side, and a cemented lens consisting of a biconcave lens and a biconvex lens.

[0163] The second lens group G2 is composed solely of a cemented lens consisting of a biconvex lens and a negative meniscus lens with its convex surface facing the image surface side.

[0164] The third lens group G3 is composed solely of a cemented lens consisting of, in order from the object side, a negative meniscus lens with its convex surface facing the object side and a biconvex lens.

[0165] The fourth lens group G4 is composed solely of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0166] The fifth lens group G5 is composed of, in order from the object side, a cemented lens consisting of a negative meniscus lens with its convex surface facing the object side and a biconvex lens, a biconvex lens, and a biconvex lens with both surfaces having a predetermined aspherical shape.

[0167] The sixth lens group G6 is composed solely of a cemented lens consisting of a positive meniscus lens with its convex surface facing the object side and a negative meniscus lens with its convex surface facing the object side, and the entire sixth lens group G6 moves toward the image plane during focusing from an infinity object distance to a close distance.

[0168] The seventh lens group G7 is composed solely of a cemented lens made up of a biconvex lens and a biconcave lens, the object-side surface of which has a predetermined aspherical shape.

[0169] Furthermore, in the variable magnification optical system of Example 7, 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 decreases, the distance between the second lens group G2 and the third lens group G3 increases and then decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, 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 decreases, the distance between the sixth lens group G6 and the seventh lens group G7 increases, and the distance between the seventh lens group G7 and the image plane increases.

[0170] In the variable magnification optical system of Example 7, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 is fixed relative to the image plane, and the second lens group G2 to the seventh lens group G7 each move relative to the image plane.

[0171] Next, the specifications of the optical system according to Example 7 are shown below. Numerical Example 7 Unit: mm [Face Data] Surface number rd nd vd θgF Object surface ∞ (d0) 1* 1000.0000 2.4290 1.59201 67.02 0.5358 2 24.3925 7.1926 3* 66.2946 1.5000 1.41390 101.00 0.5340 4* 36.1614 8.9612 5 -37.3937 1.2000 1.48749 70.44 0.5306 6 59.0660 4.7981 1.85033 42.70 0.5646 7 -120.0107 (d7) 8 87.7376 7.6542 1.55032 75.50 0.5401 9 -34.0835 0.9000 1.76634 35.82 0.5792 10 -69.4930 (d10) 11 62.9821 0.9000 1.80809 22.76 0.6287 12 37.2090 6.9916 1.72916 54.67 0.5453 13 -125.8585 (d13) 14 (Aperture) ∞ 3.6363 15 -30.8799 0.9500 1.88300 40.81 0.5656 16 49.0961 2.6492 1.98612 16.48 0.6656 17 1120.8255 (d17) 18 108.0580 0.9000 1.77047 29.74 0.5951 19 25.9194 6.2587 1.55032 75.50 0.5401 20 -58.1625 0.1500 21 34.9619 5.7498 1.59282 68.62 0.5440 22 -53.0417 0.1500 23* 41.5257 2.9825 1.59201 67.02 0.5358 24* -223.4571 (d24) 25 50.4471 1.7510 1.98612 16.48 0.6656 26 67.4639 0.9000 1.90043 37.37 0.5767 27 17.9849 (d27) 28* 57.1827 3.8815 1.77250 49.50 0.5519 29 -67.4839 0.9000 1.85451 25.15 0.6103 30 137.0342 (BF) Image plane ∞ [Aspherical data] 1st page 3rd page 4th page 23rd page 24th page K 0.00000 0.00000 0.00000 0.00000 0.00000 A4 1.15367E-05 -7.30479E-06 4.36057E-06 -8.13543E-06 7.84491E-06 A6 -1.38785E-08 -1.39626E-08 -1.86810E-08 -2.38208E-08 -3.45877E-08 A8 1.39602E-11 6.44220E-11 3.85249E-11 3.00844E-11 1.53605E-10 A10 -6.80777E-15 -6.00025E-14 -1.27425E-14 2.17025E-13 -1.76605E-13 A12 -1.56526E-18 0.00000E+00 0.00000E+00 -4.18280E-16 0.00000E+00 A14 2.63343E-21 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 28 sides K 0.00000 A4 3.80020E-06 A6 5.25127E-08 A8 -6.17941E-10 A10 4.73032E-12 A12 -1.22536E-14 A14 0.00000E+00 [Various data] Zoom ratio 2.2 Wide-angle Mid-range Telephoto Focal length 15.45 22.90 33.95 F-number 1.86 1.86 1.86 Full angle of view 2ω 90.57 62.24 43.46 Image height Y 14.20 14.20 14.20 Lens total length 133.00 133.00 133.00 [Variable Interval Data] Wide-angle Mid-range Telephoto d0 ∞ ∞ ∞ d7 22.0370 8.8612 1.2000 d10 1.0000 4.4331 1.0000 d13 1.7858 13.3366 25.3996 d17 10.0290 6.0819 1.0000 d24 3.4516 2.6940 1.5000 d27 4.8875 5.6451 6.8392 BF 16.4234 18.5622 22.6754 [Lens group data] Group Starting plane Focal length G1 1 -35.20 G2 8 92.45 G3 11 61.62 G4 14 -36.51 G5 18 19.87 G6 25 -32.82 G7 28 158.32

[0172] The values ​​corresponding to the conditional expressions for each of the above embodiments are shown below. [Conditional expression corresponding value] Conditional formula / Example EX1 EX2 EX3 EX4 EX5 EX6 EX7 (1) 0.00 0.00 0.00 -0.01 0.00 -0.04 0.00 (2) 0.16 0.16 0.14 0.12 0.23 0.23 0.16 (3) 0.16 0.16 0.14 0.13 0.23 0.27 0.16 (4) 1.21 1.21 1.23 1.12 1.14 1.36 1.13 (5) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (6) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 (7) 0.31 0.31 0.34 0.31 0.31 0.29 0.35 (8) 0.027 0.023 0.027 0.022 0.022 0.021 0.032 (9) 0.021 0.022 0.020 0.026 0.019 0.027 0.025 (10) -0.42 -0.40 -0.40 -0.40 -0.40 -0.48 -0.44 (11) 0.48 0.46 0.44 0.29 0.44 0.40 0.37 (12) 0.51 0.50 0.53 0.57 0.69 0.69 0.55 (13) -0.96 -0.96 -0.95 -0.91 -1.15 -0.88 -0.93 (14) 2.21 2.21 2.21 2.05 2.63 2.22 2.20 (15) 1.86 1.86 1.86 1.86 2.06 1.86 1.86

[0173] <Other embodiments> The technology disclosed in the present embodiment is not limited to the above-described embodiments and examples, and various modifications are possible. The shapes and numerical values ​​of each part shown in the above-described numerical examples are examples for implementing the present technology, and the technical scope of the present technology should not be interpreted as being limited by these.

[0174] Furthermore, in the above-described embodiment and example, the configuration is explained as being made up of six or seven lens groups, but the configuration may also be one including lenses that have substantially no refractive power.

[0175] Those skilled in the art will appreciate that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and they are within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0176] G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: 6th lens group G7: 7th lens group GR: Imaging lens group S: Aperture stop I: image plane C: C line (wavelength λ=656.3nm) d:d line (wavelength λ=587.6nm) g:g line (wavelength λ=435.8nm) Y: Image height ΔS: Sagittal image plane ΔM: medional image plane

Claims

1. The optical system is composed of, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, and an image-plane side lens group GR, When zooming from the wide-angle end to the telephoto end, the air gap between the first lens group G1 and the second lens group G2 decreases, the air gap between the second lens group G2 and the third lens group G3 changes, and the air gap between the third lens group G3 and the image-plane-side lens group GR increases, A variable magnification optical system characterized by satisfying the following conditional expression: (1) -0.08 < (D23T-D23W) / (D12W-D12T) < 0.08 (2) 0.08 < (D23N-D23W) / (D12W-D12T) < 0.40 (3) 0.08 < (D23N-D23T) / (D12W-D12T) < 0.40 (4) 0.50 < (D34T-D34W) / (D12W-D12T) < 2.00 however, D12W: Distance between the first lens group G1 and the second lens group G2 at the wide-angle end D12T: Distance between the first lens group G1 and the second lens group G2 at the telephoto end D23W: Distance between the second lens group G2 and the third lens group G3 at the wide-angle end D23N: Distance between the second lens group G2 and the third lens group G3 in an intermediate magnification state D23T: Distance between the second lens group G2 and the third lens group G3 at the telephoto end D34W: Distance between the third lens group G3 and the image-side lens group GR at the wide-angle end D34T: Distance between the third lens group G3 and the image-side lens group GR at the telephoto end fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end The intermediate state of magnification is when the focal length of the entire optical system is √(fw×ft) or close to it due to magnification.

2. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (5) -0.04 < (LTN-LTW) / LTW < 0.06 (6) -0.06 < (LTT-LTW) / LTW < 0.08 however, LTW: Total lens length at the wide-angle end LTN: Total lens length at intermediate magnification LTT: total length of lens at telephoto end

3. 2. The variable magnification optical system according to claim 1, wherein the first lens group G1 is fixed during magnification.

4. 2. The variable magnification optical system according to claim 1, wherein the first lens group G1 includes one or more lenses having positive refractive power and two or more lenses having negative refractive power, and the following condition is satisfied: (7) 0.20 < ndPG1-ndNG1 < 0.45 however, ndPG1: the average value of the refractive index at the wavelength of the d-line of the lenses having positive refractive power arranged in the first lens group G1 ndNG1: average value of refractive index at the wavelength of the d-line of the lens having negative refractive power arranged in the first lens group G1

5. 2. The variable magnification optical system according to claim 1, wherein the second lens group G2 includes one or more lenses having positive refractive power and one or more lenses having negative refractive power, and the following condition is satisfied: (8) dPgPG2-dPgNG2 > 0.010 however, dPgPG2: average value of deviation of partial dispersion ratio for g-line of the lens having positive refractive power arranged in the second lens group G2 dPgNG2: average value of deviation of partial dispersion ratio for g-line of the lens having negative refractive power arranged in the second lens group G2 The deviation dPgF of the partial dispersion ratio for the g-line is given by θgF for each lens, and vd for the Abbe number for the d-line. dPgF=θgF-(0.648285-0.00180123×vd) is calculated as

6. 2. The variable magnification optical system according to claim 1, wherein the image-side lens group GR includes one or more lenses having positive refractive power and one or more lenses having negative refractive power, and satisfies the following condition: (9) dPgPGR - dPgNGR > 0.010 however, dPgPGR: average value of deviation of partial dispersion ratio for g-line of lenses having positive refractive power arranged in the image-side lens group GR dPgNGR: average value of deviation of partial dispersion ratio for g-line of lenses having negative refractive power arranged in the image-side lens group GR The deviation dPgF of the partial dispersion ratio for the g-line is given by θgF for each lens, and vd for the Abbe number for the d-line. dPgF=θgF-(0.648285-0.00180123×vd) is calculated as

7. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (10) -0.60 < fw / f1 < -0.30 (11) 0.20 < ft / f2 < 0.60 (12) 0.40 < ft / f3 < 0.80 however, fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f3: focal length of the third lens group G3

8. 2. The variable magnification optical system according to claim 1, wherein the image-plane-side lens group GR comprises, in order from the object side, a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power.

9. 9. The variable magnification optical system according to claim 8, wherein the following condition is satisfied: (13) -1.40 < ft / f4 < -0.70 however, ft: focal length of the entire lens system when shooting at infinity at the telephoto end f4: focal length of the fourth lens group G4

10. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (14) 1.75 < ft / fw < 3.50 however, fw: focal length of the entire lens system when shooting at infinity at the wide-angle end ft: focal length of the entire lens system when shooting at infinity at the telephoto end

11. 2. The variable magnification optical system according to claim 1, wherein the following condition is satisfied: (15) 1.40 ≦ Fnot ≦ 2.80 however, Fnot: F-number of the entire lens system when shooting at infinity at the telephoto end

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