Variable magnification optical system

Abstract

The present invention provides a variable magnification optical system which is relatively small by appropriately changing the interval between lens groups, and which suppresses various aberrations such as spherical aberration and image plane curvature throughout a variable magnification region. The variable magnification optical system is characterized in that the variable magnification optical system is composed of 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 surface-side lens group (GR) arranged in order from the object side, and when magnification is varied from the wide-angle end to the telephoto end, the air gap between the first lens group (G1) and the second lens group (G2) is reduced, and the air gap between the third lens group (G3) and the image surface-side lens group (GR) is reduced when magnification is varied from the wide-angle end to the telephoto end. 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-surface-side lens group (GR) increases, and a predetermined conditional expression is satisfied.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical system of a photographic lens suitable for use in an image pickup device such as a still camera, a video camera, and the like, and to a variable magnification optical system which is relatively large in aperture ratio, small in size and light in weight, and corrects various aberrations such as curvature of field over the entire variable magnification region. BACKGROUND

[0002] In recent years, with high pixelization of digital cameras and the like, it is required to correct various aberrations strictly for optical systems used.

[0003] On the other hand, with the rise of smartphones and the like, in order to differentiate, it is required to perform photography with a larger blur for optical systems suitable for digital cameras and the like with a large image pickup element.

[0004] However, in the optical systems capable of performing large blur representation with a bright F number proposed in the past, a complex lens structure is often adopted in order to correct various aberrations such as spherical aberration, curvature of field, and the like, and it is difficult to achieve miniaturization.

[0005] As one example of the above-mentioned patent literature, it is disclosed in Patent Literature 1 and Patent Literature 2.

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2021-196572 Patent Literature 2: Japanese Patent Application Publication No. 2021-139930

[0007] In Patent Literature 1, a variable magnification optical system having a relatively large aperture ratio and a relatively short total lens length is proposed. However, the variable magnification optical system in Patent Literature 1 has a tendency that the curvature of field deteriorates in a state where the intermediate focal length is in the middle, and has a tendency that the chromatic aberration or the magnification chromatic aberration deteriorates on the lower axis at the telephoto end in the embodiment in which the total lens length does not change by variable magnification, and thus is not preferable.

[0008] In Patent Literature 2, a variable magnification optical system having a relatively large aperture ratio and suppressing various aberrations over the entire variable magnification region is proposed. However, the variable magnification optical system in Patent Literature 2 needs to drive a lens group closest to the object side which is heavy in weight since the total lens length changes greatly by variable magnification, and it is difficult to balance the mechanism strength and the weight reduction, and thus is not preferable. SUMMARY

[0009] An object of the present application is to provide a variable magnification optical system which is relatively small in size by appropriately changing the interval between lens groups, and suppresses various aberrations such as spherical aberration or curvature of field over the entire variable magnification region.

[0010] The first invention is a zoom optical system, characterized by comprising, 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 plane side lens group GR, wherein, when zooming from a wide angle end to a telephoto end, the air interval between the first lens group G1 and the second lens group G2 decreases, the air interval between the second lens group G2 and the third lens group G3 changes, the air interval between the third lens group G3 and the image plane side lens group GR increases, and the following conditional expressions are satisfied. (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 wherein, D12W: air interval between the first lens group G1 and the second lens group G2 at the wide angle end D12T: air interval between the first lens group G1 and the second lens group G2 at the telephoto end D23W: air interval between the second lens group G2 and the third lens group G3 at the wide angle end D23N: air interval between the second lens group G2 and the third lens group G3 at a zoom intermediate state D23T: air interval between the second lens group G2 and the third lens group G3 at the telephoto end D34W: air interval between the third lens group G3 and the image plane side lens group GR at the wide angle end D34T: air interval between the third lens group G3 and the image plane side lens group GR at the telephoto end fw: focal length of the entire lens system at the time of infinity photography at the wide angle end ft: focal length of the entire lens system at the time of infinity photography at the telephoto end The zoom intermediate state is set to a state in which the focal length of the entire optical system is √(fw x ft) or close thereto by zooming. Inventive Effects

[0011] According to the present invention, it is possible to provide a zoom optical system which is relatively large in aperture ratio, small in size, and corrects various aberrations such as spherical aberration, image surface curvature, and the like in the entire zoom region by appropriately setting the trajectories of the respective lens groups based on zooming. BRIEF DESCRIPTION OF DRAWINGS

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

[0013] Hereinafter, the embodiments of the optical system according to the present application will be described in detail. In addition, the description of the following embodiments describes an example of the variable power optical system according to the present application, and the present application is not limited to the present embodiments as long as the gist of the present application is not deviated.

[0014] is a lens sectional view at the time of infinity focus of the wide-angle end of the variable power optical system of Example 6. Figure 1 , Figure 8 , Figure 15 , Figure 22 , Figure 29 , Figure 36 , Figure 43As shown in the lens configuration diagram, the variable magnification optical system of the present application is configured by sequentially arranging, from the 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 plane side lens group GR, and when magnification is changed 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.

[0015] The present application aims to provide a variable magnification optical system that is relatively large in aperture ratio and small in size, and corrects various aberrations including image surface curvature in the entire variable magnification region, and importantly, appropriately sets the trajectories of the lens groups based on variable magnification.

[0016] In a variable magnification optical system, a method is known in which a group having a negative refractive power, a group having a positive refractive power, and a group having a positive refractive power are sequentially arranged from the object side, and the field angle at the wide angle end is kept wide while the image surface curvature in the middle of the zoom is controlled by changing the gap of the groups. However, in the arrangement of the groups as in the present application, in the case where the gap between the second lens group G2 and the third lens group G3 is widened at the wide angle end, the variable magnification function based on the second lens group G2 is limited, and on the other hand, in the case where the gap between the second lens group G2 and the third lens group G3 is widened at the telephoto end, the variable magnification function based on the third lens group G3 is limited.

[0017] In the case where the trajectories of the second lens group G2 and the third lens group G3 based on variable magnification are aligned and set to the same lens group, the variable magnification function is not limited, and the diameter of the marginal light beam incident to the third lens group G3 and the image plane side lens group GR can be suppressed, but in order to suppress the variation of the image surface curvature in the focal point region in the middle of the variable magnification, the first lens group G1 needs to be moved greatly along the optical axis. The lens diameter of the first lens group G1 is relatively large and the barrel tends to be heavy, so if the amount of movement based on variable magnification becomes large, the mechanism for holding also becomes large, and the weight of the entire optical system increases. Also, the object side of the first lens group G1 is in contact with the external air, so in the case of a large movement, the strength of the barrel or the dust and drip prevention performance also decreases.

[0018] Therefore, by setting the gap between the second lens group G2 and the third lens group G3 to a trajectory that is close to the minimum at the wide angle end and the telephoto end and is widened at the middle of the variable magnification, the variation of the image surface curvature can be suppressed while the amount of movement of the first lens group G1 is suppressed, and the optical system can be made small and light.

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

[0020] The conditional expression (1) prescribes a preferable range for the ratio of the change in the interval between the first lens group G1 and the second lens group G2 from the wide angle end to the telephoto end to the change in the interval between the second lens group G2 and the third lens group G3.

[0021] If the lower limit value of the conditional expression (1) is exceeded and the interval between the second lens group G2 and the third lens group G3 at the wide angle end becomes wide, the zooming function based on the second lens group G2 is limited, and it is difficult to secure a sufficient zooming region.

[0022] If the upper limit value of the conditional expression (1) is exceeded and the interval between the second lens group G2 and the third lens group G3 at the telephoto end becomes wide, the diameter of the marginal light beam in the third lens group G3 and the image surface side lens group GR expands, and it is difficult to make the lens barrel compact.

[0023] Further, by setting the lower limit value of the conditional expression (1) to -0.06, the effects of the present application can be more reliably achieved. Further, by setting the upper limit value of the conditional expression (1) to 0.06, the effects of the present application can be more reliably achieved.

[0024] The zoom optical system of the present application is characterized in that the following conditional expression is also satisfied. (2) 0.08 < (D23N - D23W) / (D12W - D12T) < 0.40 D23N: interval between the second lens group G2 and the third lens group G3 at the zooming intermediate state fw: focal length of the entire lens system at the time of infinity photography at the wide angle end ft: focal length of the entire lens system at the time of infinity photography at the telephoto end The zooming intermediate state is set to a state where the focal length of the entire optical system is √(fw x ft) or close thereto by zooming.

[0025] The conditional expression (2) prescribes a preferable range for the interval between the second lens group G2 and the third lens group G3 at the zooming intermediate state.

[0026] If the lower limit value of the conditional expression (2) is exceeded and the interval between the second lens group G2 and the third lens group G3 at the zooming intermediate state becomes narrow, it is difficult to suppress the image surface curvature in the vicinity of the zooming region.

[0027] If the interval between the second lens group G2 and the third lens group G3 in the zoom intermediate state becomes wider than the upper limit value of conditional expression (2), it is difficult to suppress the magnification chromatic aberration in the vicinity of the zoom region.

[0028] Further, by setting the lower limit value of conditional expression (2) to 0.10, the effect of the present application can be more reliably achieved. Further, by setting the upper limit value of conditional expression (2) to 0.35, the effect of the present application can be more reliably achieved. Moreover, in order to reliably achieve the effect of the present application, it is preferable to set the upper limit value of conditional expression (2) to 0.30.

[0029] The zoom optical system of the present application is characterized in that the following conditional expression is also satisfied. (3) 0.08 < (D23N - D23T) / (D12W - D12T) < 0.40 D23N: interval between the second lens group G2 and the third lens group G3 in the zoom intermediate state fw: focal length of the entire lens system at the time of infinity photography at the wide-angle end ft: focal length of the entire lens system at the time of infinity photography at the telephoto end The zoom intermediate state is set to a state in which the focal length of the entire optical system is √(fw x ft) or close thereto by zooming.

[0030] Conditional expression (3) specifies a preferable range for the interval between the second lens group G2 and the third lens group G3 in the zoom intermediate state.

[0031] If the interval between the second lens group G2 and the third lens group G3 in the zoom intermediate state becomes narrower than the lower limit value of conditional expression (3), it is difficult to suppress the spherical aberration in the vicinity of the zoom region.

[0032] If the interval between the second lens group G2 and the third lens group G3 in the zoom intermediate state becomes wider than the upper limit value of conditional expression (3), the spherical aberration in the vicinity of the zoom region is overcorrected, and in addition, it is difficult to suppress the magnification chromatic aberration.

[0033] Further, by setting the lower limit value of conditional expression (3) to 0.10, the effect of the present application can be more reliably achieved. Further, by setting the upper limit value of conditional expression (3) to 0.35, the effect of the present application can be more reliably achieved. Moreover, in order to reliably achieve the effect of the present application, it is preferable to set the upper limit value of conditional expression (3) to 0.30.

[0034] The zoom optical system of the present application is characterized in that the following conditional expression is also satisfied. (4) 0.50 < (D34T - D34W) / (D12W - D12T) < 2.00 D34W: interval between the 3rd lens group G3 and the image plane side lens group GR at the wide angle end D34T: interval between the 3rd lens group G3 and the image plane side lens group GR at the telephoto end

[0035] The conditional expression (4) prescribes a preferable range for the ratio of the change in the interval between the 1st lens group G1 and the 2nd lens group G2 from the wide angle end to the telephoto end to the change in the interval between the 3rd lens group G3 and the image plane side lens group GR.

[0036] If the lower limit value of the conditional expression (4) is exceeded and the interval between the 3rd lens group G3 and the image plane side lens group GR at the telephoto end becomes narrow, the zooming function based on the 3rd lens group G3 is limited, and it is difficult to secure a sufficient zooming area.

[0037] If the upper limit value of the conditional expression (4) is exceeded and the interval between the 3rd lens group G3 and the image plane side lens group GR at the telephoto end becomes wide, the diameter of the off-axis light beam in the 3rd lens group G3 and the group on the object side thereof expands, and it is difficult to downsize the lens barrel.

[0038] Further, by setting the lower limit value of the conditional expression (4) to 0.70, the effects of the present application can be more reliably achieved. Moreover, in order to reliably achieve the effects of the present application, it is preferable to set the lower limit value of the conditional expression (4) to 0.90. Further, by setting the upper limit value of the conditional expression (4) to 1.80, the effects of the present application can be more reliably achieved. Moreover, in order to reliably achieve the effects of the present application, it is preferable to set the upper limit value of the conditional expression (4) to 1.60.

[0039] Further, the zoom optical system of the present application preferably satisfies the following conditional expressions. (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 the zoom intermediate state LTT: total lens length at the telephoto end

[0040] If the lower limit value or the upper limit value of the conditional expression (5) is exceeded and the total lens length changes due to zooming, it is difficult to secure the strength or the dust and drip-proof performance of the lens barrel.

[0041] If the lower limit value or the upper limit value of the conditional expression (6) is exceeded and the total lens length changes due to zooming, it is difficult to secure the strength or the dust and drip-proof performance of the lens barrel.

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

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

[0044] Further, the zoom optical system of the present application preferably satisfies the following conditional expression.

[0045] Since the first lens group G1 is fixed at the time of zooming, it is easy to ensure the strength of the lens barrel or the dust-proof and drip-proof performance.

[0046] Further, the zoom optical system of the present application preferably satisfies the following conditional expression. (7) 0.20 < ndPG1 - ndNG1 < 0.45 ndPG1: average value of refractive index at the d-line wavelength of the lens having positive refractive power arranged in the first lens group G1 ndNG1: average value of refractive index at the d-line wavelength of the lens having negative refractive power arranged in the first lens group G1

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

[0048] If the difference between the refractive indices of the lens having positive refractive power and the lens having negative refractive power in the first lens group G1 becomes large while exceeding the upper limit value of conditional expression (7), the range of selection of glass materials that can be used is limited, and in addition, it is difficult to suppress the distortion aberration while maintaining the field angle at the wide-angle end to be wide.

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

[0050] Further, the zoom optical system of the present application preferably satisfies the following conditional expression. (8) dPgPG2 - dPgNG2 > 0.010 dPgPGR: average value of the deviation of the partial dispersion ratio for g-line of the lens having positive refractive power arranged in the image plane side lens group GR dPgNGR: average value of the deviation of the partial dispersion ratio for g-line of the lens having negative refractive power arranged in the image plane side lens group GR However, for each lens, if the partial dispersion ratio for g-line is θgF, and the Abbe number under d-line is vd, the deviation dPgF of the partial dispersion ratio for g-line is calculated as dPgF = θgF - (0.648285 - 0.00180123 x vd).

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

[0052] Further, by setting the lower limit value of the conditional expression (8) to 0.015, the effect of the present application can be more reliably achieved.

[0053] Further, the variable magnification optical system of the present application is preferably further characterized in that the image plane 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 conditional expression. (9) dPgPGR - dPgNGR > 0.010 dPgPGR: average value of the deviation of the partial dispersion ratio for g-line of the lens having positive refractive power arranged in the image plane side lens group GR dPgNGR: average value of the deviation of the partial dispersion ratio for g-line of the lens having negative refractive power arranged in the image plane side lens group GR As with the conditional expression (8), for each lens, if the partial dispersion ratio for g-line is θgF, and the Abbe number under d-line is vd, the deviation dPgF of the partial dispersion ratio for g-line is calculated as dPgF = θgF - (0.648285 - 0.00180123 x vd).

[0054] If the difference between the partial dispersion ratio for g-line of the lens having positive refractive power and the lens having negative refractive power in the image plane side lens group GR becomes smaller than the lower limit value of the conditional expression (9), it is difficult to suppress the magnification chromatic aberration on the wide angle end side or the on-axis chromatic aberration on the tele side.

[0055] Further, by setting the lower limit value of the conditional expression (9) to 0.015, the effect of the present application can be more reliably achieved.

[0056] Further, the variable magnification optical system of the present application is preferably further characterized in satisfying 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 time of photographing at infinity at the wide-angle end ft: focal length of the entire lens system at the time of photographing 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 value of the conditional expression (10) is exceeded and the negative refractive power of the first lens group G1 becomes stronger, the marginal light beam becomes thick, and it is difficult to suppress the diameters of the lenses after the second lens group G2.

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

[0059] Further, by setting the lower limit value of the conditional expression (10) to -0.55, the effects of the present application can be more reliably achieved. Further, by setting the upper limit value of the conditional expression (10) to -0.35, the effects of the present application can be more reliably achieved.

[0060] If the lower limit value of the conditional expression (11) is exceeded and the positive refractive power of the second lens group G2 becomes weaker, the marginal light beam becomes thick, and it is difficult to suppress the diameters of the lenses after the third lens group G3.

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

[0062] Further, by setting the lower limit value of the conditional expression (11) to 0.25, the effects of the present application can be more reliably achieved. Further, by setting the upper limit value of the conditional expression (11) to 0.55, the effects of the present application can be more reliably achieved.

[0063] If the lower limit value of the conditional expression (12) is exceeded and the positive refractive power of the third lens group G3 becomes weaker, it is difficult to sufficiently secure the zoom function by the change from the wide-angle end to the telephoto end.

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

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

[0066] Further, the zoom optical system of the present application is preferably further configured such that the image plane side lens group GR is configured with a fourth lens group G4 having a negative refractive power and a fifth lens group G5 having a positive refractive power in this order from the object side.

[0067] By being configured in this way, variation in spherical aberration or non-point aberration can be appropriately controlled.

[0068] Further, the zoom optical system of the present application is preferably further configured such that the following conditional expression is satisfied. (13) -1.40 < ft / f4 < -0.70 f4: focal length of the fourth lens group G4

[0069] If the lower limit value of conditional expression (13) is exceeded and the negative refractive power of the fourth lens group G4 becomes stronger, the marginal ray becomes thick, and it is difficult to suppress the diameter of the lens after the fifth lens group G5.

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

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

[0072] Further, the zoom optical system of the present application is preferably further configured such that the following conditional expression is satisfied. (14) 1.75 < ft / fw < 3.50

[0073] If the lower limit value of conditional expression (14) is exceeded and the zoom ratio of the optical system becomes smaller, it is difficult to obtain convenience as a zoom optical system. If the upper limit value of conditional expression (14) is exceeded and the zoom ratio of the optical system becomes larger, it is difficult to achieve miniaturization while maintaining high imaging performance.

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

[0075] Further, the zoom optical system of the present application is preferably further configured such that the following conditional expression is satisfied. (15) 1.40 < Fnot < 2.80 Fnot: F number of the entire system of the lens at the time of photographing at infinity at the telephoto end

[0076] If the lower limit value of conditional expression (15) is exceeded and the F number of the optical system becomes brighter, it is difficult to achieve miniaturization while maintaining high imaging performance. If the upper limit value of conditional expression (15) is exceeded and the F number becomes darker, it is difficult to perform photographing using a large blur, or photographing with a shutter speed shortened in a dark place.

[0077] Further, by setting the lower limit value of conditional expression (15) to 1.60, the effects of the present application can be more reliably achieved. Further, by setting the upper limit value of conditional expression (15) to 2.40, the effects of the present application can be more reliably achieved.

[0078] Next, the lens structure, numerical examples, and conditional expression correspondence values of the embodiments relating to the variable magnification optical system of the present application will be described. In the following description, the lens structure is described in order from the object side to the image side.

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

[0080] The * (asterisk) attached to the surface number indicates that the lens surface thereof is an aspherical surface. Further, BF indicates the back focal length.

[0081] The (stop) attached to the surface number indicates that the aperture stop is located at that position. ∞ (infinity) is written in the radius of curvature with respect to the plane or aperture stop.

[0082] The values of the coefficients of the aspherical surface shape of the lens surface to which the * is assigned in the [surface data] are shown in the [aspherical surface data]. The shape of the aspherical surface is represented by the following expression. In the following expression, y indicates the displacement from the optical axis to the direction orthogonal to the optical axis, z indicates the displacement (amount of sag) from the intersection of the aspherical surface and the optical axis to the optical axis direction, r indicates the radius of curvature of the reference sphere, and K indicates the conic coefficient. Further, when the aspherical surface coefficients of 4th, 6th, 8th, 10th, 12th, and 14th orders are respectively set to A4, A6, A8, A10, A12, and A14, the coordinates of the aspherical surface are represented by the following expression.

[0083]

[0084] The values of the aspherical surface shape of the lens surface to which the * is assigned in the [surface data] are shown in the [aspherical surface data]. The shape of the aspherical surface is represented by the following expression. In the following expression, y indicates the displacement from the optical axis to the direction orthogonal to the optical axis, z indicates the displacement (amount of sag) from the intersection of the aspherical surface and the optical axis to the optical axis direction, r indicates the radius of curvature of the reference sphere, and K indicates the conic coefficient. Further, when the aspherical surface coefficients of 4th, 6th, 8th, 10th, 12th, and 14th orders are respectively set to A4, A6, A8, A10, A12, and A14, the coordinates of the aspherical surface are represented by the following expression.

[0085] Variable intervals and BF values in each focal state are shown in [Variable Interval Data].

[0086] The face number of the most object side face constituting each lens group and the composite focal length of the entire group are shown in [Lens Group Data].

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

[0088] In addition, in all of the following specification values, unless otherwise specified, the focal length f, the radius of curvature r, the lens face interval d, and the units of other lengths are in millimeters (mm), but even if the scale is enlarged or reduced, equivalent optical performance can be obtained in the optical system, and thus it is not limited thereto. [Embodiment 1]

[0089] Figure 1 is a structural diagram of the optical system of Embodiment 1 of the present application.

[0090] The optical system of Embodiment 1 is composed of a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, a third lens group G3 of positive refractive power, and an image surface side lens group GR, which are sequentially arranged from the object side. The image surface side lens group GR is composed of a fourth lens group G4 of negative refractive power, a fifth lens group G5 of positive refractive power, a sixth lens group G6 of negative refractive power, and a seventh lens group G7 of positive refractive power, which are sequentially arranged from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0091] The first lens group G1 is composed of a negative meniscus lens having a convex surface toward the object side with a prescribed aspherical shape, a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are sequentially arranged from the object side.

[0092] The second lens group G2 is composed only of a cemented lens including a double convex lens and a negative meniscus lens with a convex surface toward the image surface side.

[0093] The third lens group G3 is composed only of a cemented lens including a negative meniscus lens with a convex surface toward the object side and a double convex lens, which are sequentially arranged from the object side.

[0094] The fourth lens group G4 is composed only of a cemented lens including a double concave lens and a positive meniscus lens with a convex surface toward the object side.

[0095] The 5th lens group G5 is composed of a cemented lens including a biconcave lens and a biconvex lens, a biconvex lens, and a positive meniscus lens having a prescribed aspheric shape on both surfaces and convex toward the object side, arranged in order from the object side.

[0096] The 6th lens group G6 is composed of only a negative meniscus lens convex toward the object side. The 6th lens group G6 moves as a whole toward the image side upon focusing from an infinite object distance to a close distance.

[0097] The 7th lens group G7 is composed of only a cemented lens including a biconvex lens having a prescribed aspheric shape on the surface toward the object side and a biconcave lens.

[0098] Also, the variable magnification optical system of Embodiment 1, upon variable magnification from the wide angle end to the telephoto end, the interval between the 1st lens group G1 and the 2nd lens group G2 decreases, the interval between the 2nd lens group G2 and the 3rd lens group G3 increases and then decreases, the interval between the 3rd lens group G3 and the 4th lens group G4 increases, the interval between the 4th lens group G4 and the 5th lens group G5 decreases, the interval between the 5th lens group G5 and the 6th lens group G6 decreases, the interval between the 6th lens group G6 and the 7th lens group G7 increases, and the interval between the 7th lens group G7 and the image plane increases.

[0099] Also, the variable magnification optical system of Embodiment 1, upon variable magnification from the wide angle end to the telephoto end, the 1st lens group G1 is fixed with respect to the image plane, and the 2nd lens group G2 to the 7th lens group G7 respectively move with respect to the image plane.

[0100] Next, the following shows the specification values of the optical system relating to Embodiment 1. Numerical Embodiment 1 Units: mm [Surface Data] [Aspheric Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 2]

[0101] Figure 8 is a structural view of the optical system of Embodiment 2 of the present application.

[0102] The optical system of Example 2 is composed of 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 plane side lens group GR, which are arranged in this order from the object side. The image plane side lens group GR is composed of a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, a sixth lens group G6 having a negative refractive power, and a seventh lens group G7 having a positive refractive power, which are arranged in this order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0103] The first lens group G1 is composed of a negative meniscus lens having a convex surface toward the object side with a prescribed aspherical shape, a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are arranged in this order from the object side.

[0104] The second lens group G2 is composed of only a cemented lens including a double convex lens and a negative meniscus lens having a convex surface toward the image plane side.

[0105] The third lens group G3 is composed of only a cemented lens including a negative meniscus lens having a convex surface toward the object side and a double convex lens, which are arranged in this order from the object side.

[0106] The fourth lens group G4 is composed of only a cemented lens including a double concave lens and a positive meniscus lens having a convex surface toward the object side.

[0107] The fifth lens group G5 is composed of a cemented lens including a double concave lens and a double convex lens, a double convex lens, and a positive meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, which are arranged in this order from the object side.

[0108] The sixth lens group G6 is composed of only a negative meniscus lens having a convex surface toward the object side. The sixth lens group G6 moves as a whole toward the image plane side at the time of focusing from an infinite object distance to a close distance.

[0109] The seventh lens group G7 is composed of only a cemented lens including a double convex lens having a prescribed aspherical shape on the object side surface and a double concave lens.

[0110] Further, the zoom optical system of Embodiment 2 is such that, when zooming from the wide-angle end to the telephoto end, the interval between the first lens group G1 and the second lens group G2 decreases, the interval between the second lens group G2 and the third lens group G3 increases and then decreases, the interval between the third lens group G3 and the fourth lens group G4 increases, the interval between the fourth lens group G4 and the fifth lens group G5 decreases, the interval between the fifth lens group G5 and the sixth lens group G6 decreases, the interval between the sixth lens group G6 and the seventh lens group G7 increases, and the interval between the seventh lens group G7 and the image plane increases.

[0111] Further, the zoom optical system of Embodiment 2 is such that, when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed with respect to the image plane, and the second lens group G2 to the seventh lens group G7 are moved with respect to the image plane, respectively.

[0112] Next, the specification values of the optical system according to Embodiment 2 are shown below. Numerical Embodiment 2 Units: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 3]

[0113] Figure 15 is a structural view of the optical system according to Embodiment 3 of the present application.

[0114] The optical system according to Embodiment 3 is composed of a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, a third lens group G3 of positive refractive power, and an image plane side lens group GR arranged in this order from the object side. The image plane side lens group GR is composed of a fourth lens group G4 of negative refractive power, a fifth lens group G5 of positive refractive power, a sixth lens group G6 of negative refractive power, and a seventh lens group G7 of positive refractive power arranged in this order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0115] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens having a convex surface toward the object side, a negative meniscus lens having both surfaces with prescribed aspherical shapes with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens.

[0116] The second lens group G2 is composed of a cemented lens including a double convex lens and a double concave lens, and a double convex lens.

[0117] The third lens group G3 is composed of only a cemented lens including, in order from the object side, a negative meniscus lens having a convex surface toward the object side and a double convex lens.

[0118] The fourth lens group G4 is composed of only a cemented lens including a double concave lens and a positive meniscus lens having a convex surface toward the object side.

[0119] The fifth lens group G5 is composed of, in order from the object side, a cemented lens including a double concave lens and a double convex lens, a double convex lens, and a double convex lens having both surfaces with prescribed aspherical shapes with a convex surface toward the object side.

[0120] The sixth lens group G6 is composed of only a negative meniscus lens having a convex surface toward the object side. The sixth lens group G6 is moved as a whole toward the image side upon focusing from an infinite object distance to a close distance.

[0121] The seventh lens group G7 is composed of only a cemented lens including a double convex lens having an object side surface with a prescribed aspherical shape and a double concave lens.

[0122] Also, in the variable magnification optical system of Embodiment 3, when magnification is varied from the wide angle end to the telephoto end, the interval between the first lens group G1 and the second lens group G2 decreases, the interval between the second lens group G2 and the third lens group G3 increases and then decreases, the interval between the third lens group G3 and the fourth lens group G4 increases, the interval between the fourth lens group G4 and the fifth lens group G5 decreases, the interval between the fifth lens group G5 and the sixth lens group G6 decreases, the interval between the sixth lens group G6 and the seventh lens group G7 increases, and the interval between the seventh lens group G7 and the image plane increases.

[0123] Also, in the variable magnification optical system of Embodiment 3, when magnification is varied from the wide angle end to the telephoto end, the first lens group G1 is fixed with respect to the image plane, and the second lens group G2 to the seventh lens group G7 are moved with respect to the image plane, respectively.

[0124] Next, the following shows the specification values of the optical system relating to Embodiment 3. Numerical Embodiment 3 Unit: mm [Surface Data] [Aspherical surface data] [Various data] [Variable interval data] [Group data] [Example 4]

[0125] Figure 22 is a configuration diagram of the optical system of Example 4 of the present application.

[0126] The optical system of Example 4 is configured by a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, a third lens group G3 of positive refractive power, and an image plane side lens group GR, which are arranged in this order from the object side. The image plane side lens group GR is configured by a fourth lens group G4 of negative refractive power, a fifth lens group G5 of positive refractive power, a sixth lens group G6 of negative refractive power, and a seventh lens group G7 of positive refractive power, which are arranged in this order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0127] The first lens group G1 is configured by a negative meniscus lens having a convex surface of a prescribed aspherical shape toward the object side, a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are arranged in this order from the object side.

[0128] The second lens group G2 is configured only by a cemented lens including a double convex lens and a negative meniscus lens having a convex surface toward the image plane side.

[0129] The third lens group G3 is configured only by a cemented lens including a negative meniscus lens having a convex surface toward the object side and a double convex lens, which are arranged in this order from the object side.

[0130] The fourth lens group G4 is configured only by a cemented lens including a double concave lens and a positive meniscus lens having a convex surface toward the object side.

[0131] The fifth lens group G5 is configured by a cemented lens including a double concave lens and a double convex lens, a double convex lens, and a double convex lens having prescribed aspherical shapes on both surfaces, which are arranged in this order from the object side.

[0132] The 6th lens group G6 is composed of only a cemented lens including a positive meniscus lens having a convex surface toward the object side and a negative meniscus lens having a convex surface toward the object side. The 6th lens group G6 is moved as a whole toward the image side upon focusing from an infinite object distance to a close distance.

[0133] The 7th lens group G7 is composed of only a cemented lens including a biconvex lens having a surface toward the object side having a prescribed aspherical shape and a biconcave lens.

[0134] Also, the variable magnification optical system of Embodiment 4, upon variable magnification from the wide angle end to the telephoto end, the interval between the 1st lens group G1 and the 2nd lens group G2 decreases, the interval between the 2nd lens group G2 and the 3rd lens group G3 increases and then decreases, the interval between the 3rd lens group G3 and the 4th lens group G4 increases, the interval between the 4th lens group G4 and the 5th lens group G5 decreases, the interval between the 5th lens group G5 and the 6th lens group G6 decreases, the interval between the 6th lens group G6 and the 7th lens group G7 increases, and the interval between the 7th lens group G7 and the image plane increases.

[0135] Also, the variable magnification optical system of Embodiment 4, upon variable magnification from the wide angle end to the telephoto end, the 1st lens group G1 is fixed with respect to the image plane, and the 2nd lens group G2 to the 7th lens group G7 are moved with respect to the image plane, respectively.

[0136] Next, the following shows the specification values of the optical system pertaining to Embodiment 4. Numerical Embodiment 4 Units: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 5]

[0137] Figure 29 is a structural view of the optical system of Embodiment 5 of the present application.

[0138] The optical system of Example 5 is composed of 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 plane side lens group GR, which are arranged in this order from the object side. The image plane side lens group GR is composed of a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, a sixth lens group G6 having a negative refractive power, and a seventh lens group G7 having a positive refractive power, which are arranged in this order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0139] The first lens group G1 is composed of a negative meniscus lens having a convex surface toward the object side with a prescribed aspherical shape, a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are arranged in this order from the object side.

[0140] The second lens group G2 is composed of only a cemented lens including a double convex lens and a negative meniscus lens having a convex surface toward the image plane side.

[0141] The third lens group G3 is composed of only a cemented lens including a negative meniscus lens having a convex surface toward the object side and a double convex lens, which are arranged in this order from the object side.

[0142] The fourth lens group G4 is composed of only a cemented lens including a double concave lens and a double convex lens.

[0143] The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens having a convex surface toward the object side and a double convex lens, a double convex lens, and a double convex lens having prescribed aspherical shapes on both surfaces, which are arranged in this order from the object side.

[0144] The sixth lens group G6 is composed of only a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side. The sixth lens group G6 moves as a whole toward the image plane side at the time of focusing from an infinite object distance to a close distance.

[0145] The seventh lens group G7 is composed of only a cemented lens including a double convex lens having a prescribed aspherical shape on the object side surface and a double concave lens.

[0146] Further, the zoom optical system of Example 5, at the time of zooming from the wide angle end to the telephoto end, the interval between the first lens group G1 and the second lens group G2 decreases, the interval between the second lens group G2 and the third lens group G3 increases and then decreases, the interval between the third lens group G3 and the fourth lens group G4 increases, the interval between the fourth lens group G4 and the fifth lens group G5 decreases, the interval between the fifth lens group G5 and the sixth lens group G6 decreases, the interval between the sixth lens group G6 and the seventh lens group G7 increases, and the interval between the seventh lens group G7 and the image plane increases.

[0147] Further, the variable magnification optical system of Embodiment 5 is such that the first lens group G1 is fixed with respect to the image plane, and the second lens group G2 to the seventh lens group G7 are moved with respect to the image plane, when magnification is changed from the wide angle end to the telephoto end.

[0148] Next, the following shows the specification values of the optical system relating to Embodiment 5. Numerical Embodiment 5 Units: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 6]

[0149] Figure 36 is a structural view of the optical system of Embodiment 6 of the present application.

[0150] The optical system of Embodiment 6 is composed of a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, a third lens group G3 of positive refractive power, and an image plane side lens group GR, which are arranged in order from the object side. The image plane side lens group GR is composed of a fourth lens group G4 of negative refractive power, a fifth lens group G5 of positive refractive power, and a sixth lens group G6 of negative refractive power, which are arranged in order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S is moved integrally with the fourth lens group G4 at the time of variable magnification.

[0151] The first lens group G1 is composed of a negative meniscus lens having a prescribed aspherical shape on both surfaces with the convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are arranged in order from the object side.

[0152] The second lens group G2 is composed of a double convex lens having a prescribed aspherical shape on both surfaces, and a negative meniscus lens with the convex surface toward the image plane side.

[0153] The third lens group G3 is composed of only a cemented lens including a negative meniscus lens with the convex surface toward the object side and a double convex lens, which are arranged in order from the object side.

[0154] The 4th lens group G4 is composed of only a cemented lens including a biconcave lens and a positive meniscus lens convex to the object side.

[0155] The 5th lens group G5 is composed of a cemented lens including a negative meniscus lens convex to the object side and a biconvex lens, a biconvex lens, and a biconvex lens having prescribed aspherical shapes on both surfaces, arranged in order from the object side. The 5th lens group G5 moves as a whole to the object side when focusing from an infinite object distance to a close distance.

[0156] The 6th lens group G6 is composed of a cemented lens including a positive meniscus lens convex to the object side and a negative meniscus lens convex to the object side, and a biconcave lens having prescribed aspherical shapes on both surfaces, arranged in order from the object side.

[0157] Further, in the variable magnification optical system of Embodiment 6, when magnification is changed from the wide angle end to the telephoto end, the interval between the 1st lens group G1 and the 2nd lens group G2 decreases, the interval between the 2nd lens group G2 and the 3rd lens group G3 increases and then decreases, the interval between the 3rd lens group G3 and the 4th lens group G4 increases, the interval between the 4th lens group G4 and the 5th lens group G5 decreases, the interval between the 5th lens group G5 and the 6th lens group G6 changes, and the interval between the 6th lens group G6 and the image plane increases.

[0158] Further, in the variable magnification optical system of Embodiment 6, when magnification is changed from the wide angle end to the telephoto end, the 1st lens group G1 is fixed with respect to the image plane, and the 2nd lens group G2 to the 6th lens group G6 are moved with respect to the image plane, respectively.

[0159] Next, the following shows the specification values of the optical system relating to Embodiment 6. Numerical Embodiment 6 Units: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 7]

[0160] Figure 43is a structural view of the optical system of Embodiment 7 of the present application.

[0161] The optical system of Embodiment 7 is composed of a first lens group G1 of negative refractive power, a second lens group G2 of positive refractive power, a third lens group G3 of positive refractive power, and an image plane side lens group GR, which are arranged in this order from the object side. The image plane side lens group GR is composed of a fourth lens group G4 of negative refractive power, a fifth lens group G5 of positive refractive power, a sixth lens group G6 of negative refractive power, and a seventh lens group G7 of positive refractive power, which are arranged in this order from the object side. An aperture stop S is arranged between the third lens group G3 and the fourth lens group G4, and the aperture stop S moves integrally with the fourth lens group G4 at the time of zooming.

[0162] The first lens group G1 is composed of a negative meniscus lens having a convex surface toward the object side with a prescribed aspherical shape, a negative meniscus lens having prescribed aspherical shapes on both surfaces with a convex surface toward the object side, and a cemented lens including a double concave lens and a double convex lens, which are arranged in this order from the object side.

[0163] The second lens group G2 is composed of only a cemented lens including a double convex lens and a negative meniscus lens with a convex surface toward the image plane side.

[0164] The third lens group G3 is composed of only a cemented lens including a negative meniscus lens with a convex surface toward the object side and a double convex lens, which are arranged in this order from the object side.

[0165] The fourth lens group G4 is composed of only a cemented lens including a double concave lens and a positive meniscus lens with a convex surface toward the object side.

[0166] The fifth lens group G5 is composed of a cemented lens including a negative meniscus lens with a convex surface toward the object side and a double convex lens, a double convex lens, and a double convex lens having prescribed aspherical shapes on both surfaces, which are arranged in this order from the object side.

[0167] The sixth lens group G6 is composed of only a cemented lens including a positive meniscus lens with a convex surface toward the object side and a negative meniscus lens with a convex surface toward the object side. The sixth lens group G6 moves as a whole toward the image plane side at the time of focusing from an infinite object distance to a close distance.

[0168] The seventh lens group G7 is composed of only a cemented lens including a double convex lens having a prescribed aspherical shape on the object side surface and a double concave lens.

[0169] Further, the zoom optical system of Embodiment 7 increases the interval between the first lens group G1 and the second lens group G2, increases and then decreases the interval between the second lens group G2 and the third lens group G3, increases the interval between the third lens group G3 and the fourth lens group G4, decreases the interval between the fourth lens group G4 and the fifth lens group G5, decreases the interval between the fifth lens group G5 and the sixth lens group G6, increases the interval between the sixth lens group G6 and the seventh lens group G7, and increases the interval between the seventh lens group G7 and the image plane as the zooming from the wide-angle end to the telephoto end progresses.

[0170] Further, the zoom optical system of Embodiment 7 fixes the first lens group G1 with respect to the image plane and moves the second lens group G2 to the seventh lens group G7 with respect to the image plane as the zooming from the wide-angle end to the telephoto end progresses.

[0171] Next, the following shows the specification values of the optical system relating to Embodiment 7. Numerical Embodiment 7 Units: mm [Surface Data] [Aspheric Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data]

[0172] The following shows the conditional expression corresponding values corresponding to each of the above embodiments. [Conditional Expression Corresponding Values]

[0173] <OTHER EMBODIMENTS> The technology disclosed by the present embodiment is not limited to the description of the above embodiments and examples, and various modifications can be made. The shapes and values of each part shown in the above numerical examples are one example for implementing the technology, and the scope of the technology is not to be construed as being limited by these shapes and values.

[0174] Further, in the above embodiments and examples, the structure including six or seven lens groups is described, but a structure having a lens having substantially no refractive power can also be used.

[0175] Various modifications, combinations, sub-combinations and alterations can occur to one of ordinary skill in the art based on the overall teachings contained in the present disclosure. Those skilled in the art will recognize that some aspects of the disclosure, depending on the embodiment, can be changed or modified without departing from the scope of the present disclosure. These include, but are not limited to, variations in sizes, materials, structures, functions and / or components. These and other changes can be made to the disclosure in light of the overall teachings of the disclosure. In general, the only such changes to the disclosure will be those that do not fall within the meaning and range of equivalents of the claims. Accordingly, while the specific teachings of the present disclosure can be preferred, various modifications, changes and substitutions are intended in the scope of the present disclosure. Explanation of symbols

[0176] G1 - 1st lens group, G2 - 2nd lens group, G3 - 3rd lens group, G4 - 4th lens group, G5 - 5th lens group, G6 - 6th lens group, G7 - 7th lens group, GR - lens group on image side, S - aperture stop, I - image plane, C - C line (wavelength λ = 656.3 nm), d - d line (wavelength λ = 587.6 nm), g - g line (wavelength λ = 435.8 nm), Y - image height, ΔS - sagittal image plane, ΔM - meridional image plane.

Claims

1. A zoom optical system, characterized in that, It consists of 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-plane-side lens group (GR), arranged sequentially from the object side. 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-side lens group (GR) increases. And satisfy 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 in, D12W is the spacing between the first lens group (G1) and the second lens group (G2) at the wide-angle end. D12T is the interval between the first lens group (G1) and the second lens group (G2) at the telephoto end. D23W is the spacing between the second lens group (G2) and the third lens group (G3) at the wide-angle end. D23N is the interval between the second lens group (G2) and the third lens group (G3) in the intermediate zoom state. D23T is the interval between the second lens group (G2) and the third lens group (G3) at the telephoto end. D34W is the spacing between the third lens group (G3) and the image-side lens group (GR) at the wide-angle end. D34T is the spacing between the third lens group (G3) and the image-side lens group (GR) at the telephoto end. fw is the focal length of the entire lens system when shooting at infinity at the wide-angle end. ft is the focal length of the entire lens system when taking infinity photographs at the telephoto end. The zoom intermediate state is defined as the state in which the focal length of the entire optical system is √(fw×ft) or close to √(fw×ft) after zooming.

2. The zoom optical system according to claim 1, characterized in that, The following conditions must be met. (5)-0.04<(LTN-LTW) / LTW<0.06 (6)-0.06<(LTT-LTW) / LTW<0.08 in, LTW is the total length of the lens at the wide-angle end. LTN is the total length of the lens at the intermediate zoom level. LTT is the total length of the lens at the telescope end.

3. The zoom optical system according to claim 1, characterized in that, The first lens group (G1) is fixed during zoom.

4. The zoom optical system according to claim 1, characterized in that, The first lens group (G1) comprises one or more lenses with positive refractive power and two or more lenses with negative refractive power, and satisfies the following condition: (7) 0.20 < ndPG1 - ndNG1 < 0.45 in, ndPG1 is the average refractive index at the d-line wavelength of the lens with positive refractive power configured in the first lens group (G1). ndNG1 is the average value of the refractive index at the d-line wavelength of the lens with negative refractive power configured in the first lens group (G1).

5. The zoom optical system according to claim 1, characterized in that, The second lens group (G2) includes one or more lenses with positive refractive power and one or more lenses with negative refractive power, and satisfies the following condition: (8) dPgPG2-dPgNG2>0.010 in, dPgPG2 is the average value of the deviation of the partial dispersion ratio of the lens with positive refractive power configured in the second lens group (G2) with respect to the g-line. dPgNG2 is the average value of the deviation of the partial dispersion ratio of the lens with negative refractive power disposed in the second lens group (G2) with respect to the g line. For each lens, if the partial dispersion ratio for the g-line is θgF, and the Abbe number for the d-line is vd, then the deviation dPgF of the partial dispersion ratio for the g-line is calculated as follows: dPgF=θgF-(0.648285-0.00180123×vd).

6. The zoom optical system according to claim 1, characterized in that, The image-side lens group (GR) includes one or more lenses with positive refractive power and one or more lenses with negative refractive power, and satisfies the following condition: (9) dPgPGR-dPgNGR>0.010 in, dPgPGR is the average deviation of the partial dispersion ratio of the lens with positive refractive power disposed in the image-side lens group (GR) for the g-line. dPgNGR is the average deviation of the partial dispersion ratio of the lens with negative refractive power disposed in the image-side lens group (GR) with respect to the g-line. For each lens, if the partial dispersion ratio for the g-line is θgF, and the Abbe number for the d-line is vd, then the deviation dPgF of the partial dispersion ratio for the g-line is calculated as follows: dPgF=θgF-(0.648285-0.00180123×vd).

7. The zoom optical system according to claim 1, characterized in that, The following conditions must be met. (10) -0.60 < fw / f1 < -0.30 (11) 0.20 < ft / f2 < 0.60 (12) 0.40 < ft / f3 < 0.80 in, fw is the focal length of the entire lens system when shooting at infinity at the wide-angle end. ft is the focal length of the entire lens system when taking infinity photographs at the telephoto end. f1 is the focal length of the first lens group (G1). f2 is the focal length of the second lens group (G2). f3 is the focal length of the third lens group (G3).

8. The zoom optical system according to claim 1, characterized in that, The image-side lens group (GR) is arranged sequentially from the object side as a fourth lens group (G4) with negative refractive power and a fifth lens group (G5) with positive refractive power.

9. The zoom optical system according to claim 8, characterized in that, The following conditions must be met. (13) -1.40 < ft / f4 < -0.70 in, ft is the focal length of the entire lens system when taking infinity photographs at the telephoto end, and f4 is the focal length of the fourth lens group (G4).

10. The zoom optical system according to claim 1, characterized in that, The following conditions must be met. (14) 1.75 < ft / fw < 3.50 in, fw is the focal length of the entire lens system when taking infinity photography at the wide-angle end, and ft is the focal length of the entire lens system when taking infinity photography at the telephoto end.

11. The zoom optical system according to claim 1, characterized in that, The following conditions must be met. (15) 1.40 ≤ Fnot ≤ 2.80 in, Fnot is the F-number of the entire lens system when taking infinity photographs at the telephoto end.

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