Variable power optical system and imaging apparatus

Abstract

The invention provides a variable magnification optical system and an imaging apparatus. A variable magnification optical system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power arranged in order from an object side, the variable magnification optical system being characterized in that the interval between the first lens group and the second lens group changes when magnification is varied, and the interval between the fourth lens group and the fifth lens group changes when magnification is varied. The variable magnification optical system satisfies a specific conditional expression in which an interval between the second lens group and the third lens group varies, an interval between the third lens group and the fourth lens group varies, and when focusing from an infinite end to a very near end, any one of the fourth lens group and the fifth lens group moves along an optical axis.

Description

TECHNICAL FIELD

[0001] The present application relates to a zoom optical system and an image pickup apparatus. BACKGROUND

[0002] As a zoom optical system for an image pickup apparatus, there is a demand for a small size, a large aperture ratio, a high zoom ratio, and good correction of each aberration.

[0003] Conventionally, a zoom optical system that is small in size and corresponds to a large image pickup element and that has good correction of each aberration from a wide angle end to a telephoto end has been proposed (for example, Patent Literature 1). Also, a small zoom optical system that has a high zoom ratio, a wide field angle, and good optical performance, and an optical device that mounts the zoom optical system have been proposed (for example, Patent Literature 2). Further, a zoom optical system that has a large aperture ratio, is small in size as a whole, and has excellent optical performance, and an image pickup apparatus that has the zoom optical system have been proposed (for example, Patent Literature 3).

[0004] Patent Literature 1: WO 2019 / 049370 Patent Literature 2: Japanese Patent Application Publication No. 2020-071439 Patent Literature 3: Japanese Patent Application Publication No. 2023-004721

[0005] Non-Patent Literature 1: Yoshinori Matsui, Lens Design Method, Kyodo Shuppan Co., Ltd., issued November 5, 1972, pp. 77-128 Non-Patent Literature 2: Yoshinori Matsui, “Standardization of Aberration Coefficients for New Optical Systems”, Optical Review, The Optical Society of Japan, issued October 1994, Vol. 23, No. 10, pp. 634-640 Non-Patent Literature 3: Hiroshi Inoue, Inspection Technology of Optical Elements and Mechanisms Revised Edition II, Mechanism Group, Optronics Co., Ltd., issued April 10, 2009, pp. 95-96

[0006] In the above-described background art, it is difficult to provide a zoom optical system that achieves sufficient miniaturization, large aperture ratio, and high zoom ratio, and that has good correction of each aberration. For example, it is difficult to achieve a large aperture ratio in the zoom optical system described in Patent Literature 2, and it is difficult to achieve a high zoom ratio in the zoom optical systems described in Patent Literature 1 and Patent Literature 3.

[0007] As a zoom optical system for an image pickup apparatus, the present application provides a zoom optical system that is small in size, that can achieve a large aperture ratio and a high zoom ratio of the zoom optical system, and that has good correction of each aberration. SUMMARY

[0008] To solve the above problems, the present application provides a zoom optical system having, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power, wherein the interval between the first lens group G1 and the second lens group G2 changes when zooming from the wide-angle end to the telephoto end, the interval between the second lens group G2 and the third lens group G3 changes, the interval between the third lens group G3 and the fourth lens group G4 changes, either one of the fourth lens group G4 and the fifth lens group G5 moves along the optical axis when focusing from the infinity end to the close-up end, the third lens group G3 has at least one negative lens, the lens surface on the object side of the negative lens L3n arranged closest to the image side in the third lens group G3 is convex toward the image side, the fourth lens group G4 has at least one negative lens, the lens surface on the object side of the negative lens L4n arranged closest to the object side in the fourth lens group G4 is convex toward the image side, and the zoom optical system satisfies the following conditional expressions. (1) 0.61 < f34 / fW < 1.46 (2) 0.32 < f4 / f3 < 0.96 (3) -0.0085 < ΔPgF1 + ΔPgF2 < 0.0070 f34: combined focal length of the third lens group G3 to the fourth lens group G4, wherein f34 = 1 / (∑(1 / fn)), n = 3-4. fn is the focal length of the nth lens group. fW: focal length at the wide-angle end of the zoom optical system f4: focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: abnormal dispersion of the negative lens L3n arranged closest to the image side in the third lens group G3, wherein ΔPgF1 = PgF1 - 0.64833 + 0.00180 x νd1. PgF1 is the partial dispersion ratio for g-line and F-line of the negative lens L3n arranged closest to the image side in the third lens group G3. νd1 is the Abbe number for d-line of the negative lens L3n arranged closest to the image side in the third lens group G3. ΔPgF2: abnormal dispersion of the negative lens L4n arranged closest to the object side in the fourth lens group G4, wherein ΔPgF2 = PgF2 - 0.64833 + 0.00180 x νd2. PgF2 is the partial dispersion ratio for g-line and F-line of the negative lens L4n arranged closest to the object side in the fourth lens group G4. νd2 is the Abbe number for d-line of the negative lens L4n arranged closest to the object side in the fourth lens group G4. Inventive Effects

[0009] According to the present application, as a zoom optical system for an image pickup device, it is possible to provide a zoom optical system which is small in size, which enables large-aperture magnification and high zoom ratio, and which is well corrected for each aberration. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a cross-sectional view at the time of focusing on an infinite object at the wide-angle end involved in Example 1. Figure 2A , Figure 2B and Figure 2C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 1. Figure 3A , Figure 3B and Figure 3C are lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 1. Figure 4 is a cross-sectional view at the time of focusing on an infinite object at the wide-angle end involved in Example 2. Figure 5A , Figure 5B and Figure 5C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 2. Figure 6A , Figure 6B and Figure 6C are lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 2. Figure 7 is a cross-sectional view at the time of focusing on an infinite object at the wide-angle end involved in Example 3. Figure 8A , Figure 8B and Figure 8C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 3. Figure 9A , Figure 9B and Figure 9C are lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 3. Figure 10 is a cross-sectional view at the time of focusing on an infinite object at the wide-angle end involved in Example 4. Figure 11A , Figure 11B and Figure 11C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focus, and the telephoto end, respectively, involved in Example 4. Figure 12A , Figure 12B and Figure 12C are the lateral aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 4. Figure 13 is the cross section diagram for the wide angle end for an infinite object focus of Example 5. Figure 14A , Figure 14B and Figure 14C are the longitudinal aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 5. Figure 15A , Figure 15B and Figure 15C are the lateral aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 5. Figure 16 is the cross section diagram for the wide angle end for an infinite object focus of Example 6. Figure 17A , Figure 17B and Figure 17C are the longitudinal aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 6. Figure 18A , Figure 18B and Figure 18C are the lateral aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 6. Figure 19 is the cross section diagram for the wide angle end for an infinite object focus of Example 7. Figure 20A , Figure 20B and Figure 20C are the longitudinal aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 7. Figure 21A , Figure 21B and Figure 21C are the lateral aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 7. Figure 22 is the cross section diagram for the wide angle end for an infinite object focus of Example 8. Figure 23A , Figure 23B and Figure 23C are the longitudinal aberration diagrams for the wide angle end, intermediate focal length, and telephoto end, respectively, for an infinite object focus of Example 8. Figure 24A , Figure 24B andFigure 24C are lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, in Example 8. Figure 25A , Figure 25B and Figure 25C are lateral aberration diagrams at the time of vibration-proofing with an image blur correction angle of 0.3° at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, in Example 8. Figure 26 is a view showing the structure of an imaging device provided with the variable magnification optical system of the present application. DETAILED DESCRIPTION

[0011] Hereinafter, the variable magnification optical system of the present application and the imaging device equipped with the variable magnification optical system will be described. First, the embodiments of the present application will be described.

[0012] In the present application, in the case of counting the number of lens pieces, a single lens is counted as one piece unless otherwise specified, and in the case of a cemented lens, each single lens constituting the cemented lens is counted as one piece. For example, if it is a cemented lens of a convex lens and a concave lens, it is counted as two pieces.

[0013] The variable magnification optical system of the present application is characterized by having, in order from the object side, a first lens group G1 of positive refractive power, a second lens group G2 of negative refractive power, a third lens group G3 of positive refractive power, a fourth lens group G4 of positive refractive power, and a fifth lens group G5 of negative refractive power, the interval between the first lens group G1 and the second lens group G2 changes when zooming from the wide-angle end to the telephoto end, the interval between the second lens group G2 and the third lens group G3 changes, the interval between the third lens group G3 and the fourth lens group G4 changes, either one of the fourth lens group G4 and the fifth lens group G5 moves along the optical axis when focusing from the infinite end to the closest end, the third lens group G3 has at least one negative lens, the lens surface on the object side of the negative lens L3n disposed most on the image side in the third lens group G3 is convex toward the image side, the fourth lens group G4 has at least one negative lens, the lens surface on the object side of the negative lens L4n disposed most on the object side in the fourth lens group G4 is convex toward the image side, and the variable magnification optical system satisfies the following conditional expressions. (1) 0.61 < f34 / fw < 1.46 (2) 0.32 < f4 / f3 < 0.96 (3) -0.0085 < ΔPgF1 + ΔPgF2 < 0.0070 f34: composite focal length of the third lens group G3 to the fourth lens group G4. Wherein, f34 = 1 / (∑(1 / fn)), n = 3~4. fn is the focal length of the nth lens group. fW: focal length at the wide angle end of the variable magnification optical system f4: focal length of the fourth lens group G4 f3: focal length of the third lens group G3 ΔPgF1: anomalous dispersion of the most object side arranged negative lens L3n in the third lens group G3. Wherein, ΔPgF1 = PgF1 - 0.64833 + 0.00180×νd1. PgF1 is the partial dispersion ratio for g line and F line of the most object side arranged negative lens L3n in the third lens group G3. νd1 is the Abbe number for d line of the most object side arranged negative lens L3n in the third lens group G3. ΔPgF2: anomalous dispersion of the most object side arranged negative lens L4n in the fourth lens group G4. Wherein, ΔPgF2 = PgF2 - 0.64833 + 0.00180×νd2. PgF2 is the partial dispersion ratio for g line and F line of the most object side arranged negative lens L4n in the fourth lens group G4. νd2 is the Abbe number for d line of the most object side arranged negative lens L4n in the fourth lens group G4.

[0014] The structure of the present application aims at small size, realizing large aperture ratio and high magnification ratio of the variable magnification optical system, and good correction of each aberration. By setting the first lens group G1 as positive refractive power and the fifth lens group G5 as negative refractive power, it is easy to position the back principal point of the variable magnification optical system on the object side, and the variable magnification optical system can be miniaturized. And by setting the second lens group G2 as negative refractive power, when zooming from the wide angle end to the telephoto end, it is easy to suppress the change of the lateral magnification borne by the lens group arranged more on the image side than the second lens group G2, and the variable magnification optical system can be high magnification ratio.

[0015] By setting the 3rd lens group G3 and the 4th lens group G4 to be positive refractive power, it is easy to suppress the change in focal position occurring when zooming from the wide angle end to the telephoto end, without further forcibly increasing the refractive power of the 3rd lens group G3 or the 4th lens group G4, it is easy to immediately perform aberration correction within the 3rd lens group G3 and within the 4th lens group G4, and it is possible to make the zoom optical system large-aperture ratio. Also, by making the lens surface on the object side of the negative lens disposed most on the image side in the 3rd lens group G3 convex toward the image side, and making the lens surface on the object side of the negative lens disposed most on the object side in the 4th lens group G4 convex toward the image side, it is possible to effectively suppress the spherical aberration or on-axis chromatic aberration occurring within the 3rd lens group G3 and within the 4th lens group G4, and it is possible to make the zoom optical system high-zoom ratio and large-aperture ratio.

[0016] The conditional expression (1) is a conditional expression for prescribing an appropriate value for the ratio of the combined focal length of the 3rd lens group G3 and the 4th lens group G4 to the focal length at the wide angle end of the zoom optical system, and relates to the large-aperture ratio of the zoom optical system.

[0017] If the refractive power from the 3rd lens group G3 to the 4th lens group G4 is weakened to exceed the upper limit of the conditional expression (1), the off-axis aberration correction ability of the lens group disposed more on the image side than the 4th lens group G4 decreases, and in particular it is difficult to correct the non-point aberration at the telephoto end. If the refractive power from the 3rd lens group G3 to the 4th lens group G4 is strengthened to exceed the lower limit of the conditional expression (1), the on-axis aberration correction ability in that lens group decreases, and in particular it is difficult to correct the spherical aberration from the wide angle end to the telephoto end.

[0018] In addition, in order to make the effects of the present application more reliable, the conditional expression (1) preferably sets the upper limit value to 1.32 and the lower limit value to 0.67, and further preferably sets the upper limit value to 1.19 and the lower limit value to 0.74.

[0019] The conditional expression (2) is a conditional expression for prescribing an appropriate value for the ratio of the focal length of the 4th lens group G4 to the focal length of the 3rd lens group G3, and relates to the high-zoom ratio of the zoom optical system.

[0020] If the refractive power of the 3rd lens group G3 is strengthened to exceed the upper limit of the conditional expression (2), the correction of on-axis aberration within that lens group results in deterioration of off-axis aberration, and in particular it is difficult to correct the coma aberration at the telephoto end. If the refractive power of the 4th lens group G4 is strengthened to exceed the lower limit of the conditional expression (2), the correction of on-axis aberration within that lens group results in deterioration of off-axis aberration, and in particular it is difficult to correct the non-point aberration at the wide angle end.

[0021] In addition, in order to make the effects of the present application more reliable, the conditional expression (2) preferably sets the upper limit value to 0.91 and the lower limit value to 0.34, and further preferably sets the upper limit value to 0.87 and the lower limit value to 0.35.

[0022] Conditional expression (3) is a conditional expression for prescribing an appropriate value to the sum of the chromatic aberration correction ability of the 3rd lens group G3 and the chromatic aberration correction ability of the 4th lens group G4, and relates to the high zoom ratio of the zoom optical system.

[0023] If the sum of the anomalous dispersion of the most object side negative lens L3n in the 3rd lens group G3 and the anomalous dispersion of the most object side negative lens L4n in the 4th lens group G4 becomes larger than the upper limit of conditional expression (3), the short wavelength side behavior of the light rays passing through the 3rd lens group G3 to the 4th lens group G4 becomes excessive, and it is particularly difficult to correct the on-axis chromatic aberration at the telephoto end. If the sum of the anomalous dispersion of the most object side negative lens L3n in the 3rd lens group G3 and the anomalous dispersion of the most object side negative lens L4n in the 4th lens group G4 becomes smaller than the lower limit of conditional expression (3), the short wavelength side behavior of the light rays passing through the 3rd lens group G3 to the 4th lens group G4 is insufficient, and it is particularly difficult to correct the on-axis chromatic aberration at the wide angle end.

[0024] In addition, in order to make the effect of the present application more reliable, conditional expression (3) preferably sets the upper limit value to 0.0069 and the lower limit value to -0.0084, and further preferably sets the upper limit value to 0.0068 and the lower limit value to -0.0083.

[0025] Moreover, the zoom optical system of the present application is characterized by satisfying the following conditional expression. (4) 0.13 < |f13| / f4L < 1.25 f13: the combined focal length of the 1st lens group G1 to the 3rd lens group G3. Wherein, f13 = 1 / (Σ(1 / fn)), n = 1 ~ 3. fn is the focal length of the nth lens group. f4L: the combined focal length of the 4th lens group G4 to the lens group disposed most object side (hereinafter, the final lens group GL). Wherein, f4L = 1 / (Σ(1 / fn)), n = 4 ~ L. fn is the focal length of the nth lens group. fL is the focal length of the final lens group.

[0026] Conditional expression (4) is a conditional expression for prescribing an appropriate value to the ratio of the combined focal length of the 1st lens group G1 to the 3rd lens group G3 and the combined focal length of the 4th lens group G4 to the lens group disposed most object side (hereinafter, the final lens group GL), and relates to the total length shortening of the zoom optical system.

[0027] If the refractive power of the 4th lens group to the final lens group GL is made stronger than the upper limit of the conditional expression (4), the off-axis aberration correction ability in the 4th lens group G4 to the final lens group GL decreases, and it is particularly difficult to correct the coma aberration at the telephoto end. If the refractive power of the 1st lens group G1 to the 3rd lens group G3 is made stronger than the lower limit of the conditional expression (4), the off-axis aberration correction ability in the 1st lens group G1 to the 3rd lens group G3 decreases, and it is particularly difficult to correct the non-point aberration at the wide angle end.

[0028] Further, in order to make the effect of the present application more reliable, the conditional expression (4) is preferably set to have an upper limit value of 0.95 and a lower limit value of 0.16, and further preferably set to have an upper limit value of 0.78 and a lower limit value of 0.20.

[0029] Further, the zoom optical system of the present application is characterized by satisfying the following conditional expression. (5) 1.12 < m4 / m3 < 1.56 m4: movement amount of the 4th lens group G4 when zooming from the wide angle end to the telephoto end (movement to the object side is taken as positive) m3: movement amount of the 3rd lens group G3 when zooming from the wide angle end to the telephoto end (movement to the object side is taken as positive)

[0030] The conditional expression (5) is a conditional expression for regulating an appropriate value to the ratio of the total movement amount of the 4th lens group G4 when zooming to the total movement amount of the 3rd lens group G3 when zooming, and relates to the aberration correction ability of the zoom optical system.

[0031] If the distance between the 3rd lens group G3 and the 4th lens group G4 at the wide angle end is made further apart than the upper limit of the conditional expression (5), the off-axis chief ray height of the 4th lens group G4 at the wide angle end excessively increases, and it is particularly difficult to correct the non-point aberration at the wide angle end. If the distance between the 3rd lens group G3 and the 4th lens group G4 at the wide angle end is made closer than the lower limit of the conditional expression (5), the off-axis chief ray height of the 4th lens group G4 at the wide angle end excessively decreases, and it is particularly difficult to correct the non-point aberration at the wide angle end.

[0032] Further, in order to make the effect of the present application more reliable, the conditional expression (5) is preferably set to have an upper limit value of 1.53 and a lower limit value of 1.14, and further preferably set to have an upper limit value of 1.50 and a lower limit value of 1.16.

[0033] Further, the zoom optical system of the present application is characterized by satisfying the following conditional expression. (6) 1.17 < |f5| / f4 < 2.89 f5: focal length of the 5th lens group G5 f4: focal length of the 4th lens group G4

[0034] The conditional expression (6) is a conditional expression for prescribing an appropriate value to the ratio of the focal length of the 5th lens group G5 to the focal length of the 4th lens group G4, and relates to the aberration correction ability of the zoom optical system.

[0035] If the refractive power of the 4th lens group G4 is made stronger, correction of the on-axis aberration within the lens group causes deterioration of the off-axis aberration beyond the upper limit of the conditional expression (6), and it is particularly difficult to correct the coma aberration at the telephoto end. If the refractive power of the 5th lens group G5 is made stronger beyond the lower limit of the conditional expression (6), correction of the on-axis aberration within the lens group causes deterioration of the off-axis aberration, and it is particularly difficult to correct the coma aberration at the wide angle end.

[0036] In addition, in order to make the effects of the present application more reliable, the conditional expression (6) preferably has the upper limit value set to 2.75 and the lower limit value set to 1.23, and further preferably has the upper limit value set to 2.61 and the lower limit value set to 1.29.

[0037] Furthermore, the zoom optical system of the present application is characterized by satisfying the following conditional expression. (7) 0.83 < m5 / m4 < 1.24 m5: movement amount of the 5th lens group G5 when zooming from the wide angle end to the telephoto end (positive for movement to the object side) m4: movement amount of the 4th lens group G4 when zooming from the wide angle end to the telephoto end (positive for movement to the object side)

[0038] The conditional expression (7) is a conditional expression for prescribing an appropriate value to the ratio of the total movement amount of the 5th lens group G5 when zooming to the total movement amount of the 4th lens group G4 when zooming, and relates to the aberration correction ability of the zoom optical system.

[0039] If the distance between the 4th lens group G4 and the 5th lens group G5 at the wide angle end is made further apart beyond the upper limit of the conditional expression (7), the burden of off-axis aberration correction of the 5th lens group G5 at the wide angle end increases, and it is particularly difficult to correct the coma aberration at the wide angle end. If the distance between the 4th lens group G4 and the 5th lens group G5 at the telephoto end is made further apart beyond the lower limit of the conditional expression (7), the burden of off-axis aberration correction of the 5th lens group G5 at the telephoto end increases, and it is particularly difficult to correct the coma aberration at the telephoto end.

[0040] In addition, in order to make the effects of the present application more reliable, the conditional expression (7) preferably has the upper limit value set to 1.22 and the lower limit value set to 0.84, and more preferably has the upper limit value set to 1.19 and the lower limit value set to 0.86.

[0041] Furthermore, the zoom optical system of the present application is characterized by satisfying the following conditional expression. (8) 1.34 < |f5L| / fW < 4.25 f5L: the combined focal length of the 5th lens group G5 to the final lens group GL. Wherein, f5L = 1 / (Σ(1 / fn)), n = 5 ~ L. fn is the focal length of the nth lens group. fL is the focal length of the final lens group GL. fW: the focal length at the wide angle end of the variable magnification optical system

[0042] Condition formula (8) is a condition formula for prescribing an appropriate value to the ratio of the combined focal length of the 5th lens group G5 to the final lens group GL to the focal length at the wide angle end of the variable magnification optical system, which relates to the aberration correction ability of the variable magnification optical system.

[0043] If the refractive power of the 5th lens group G5 to the final lens group GL is weakened to exceed the upper limit of condition formula (8), the on-axis aberration correction ability in the final lens group GL decreases, and it is particularly difficult to correct the spherical aberration at the telephoto end. If the refractive power of the 5th lens group G5 to the final lens group GL is strengthened to exceed the lower limit of condition formula (8), the off-axis aberration correction ability in the final lens group GL decreases, and it is particularly difficult to correct the non-point aberration at the wide angle end.

[0044] In addition, in order to make the effect of the present application more reliable, condition formula (8) preferably sets the upper limit value to 3.84 and the lower limit value to 1.49, and further preferably sets the upper limit value to 3.46 and the lower limit value to 1.65.

[0045] Furthermore, the variable magnification optical system of the present application is characterized by satisfying the following condition formula. (9) 0.51 < bfW / fW < 1.85 bfW: the back focal length at the wide angle end of the variable magnification optical system fW: the focal length at the wide angle end of the variable magnification optical system

[0046] Condition formula (9) is a condition formula for prescribing an appropriate value to the ratio of the back focal length at the wide angle end to the focal length at the wide angle end of the variable magnification optical system, which relates to the aberration correction ability of the variable magnification optical system.

[0047] If the distance between the final lens group GL and the image plane is far away to exceed the upper limit of condition formula (9), it leads to the decrease of the off-axis aberration correction ability in the final lens group GL, and it is particularly difficult to correct the non-point aberration at the wide angle end to the telephoto end. If the distance between the final lens group GL and the image plane is close to exceed the lower limit of condition formula (9), it leads to the decrease of the on-axis aberration correction ability in the final lens group GL, and it is particularly difficult to correct the spherical aberration at the wide angle end to the telephoto end.

[0048] In addition, in order to make the effect of the present application more reliable, condition formula (9) preferably sets the upper limit value to 1.76 and the lower limit value to 0.53, and more preferably sets the upper limit value to 1.68 and the lower limit value to 0.56.

[0049] Further, the variable magnification optical system of the present application is characterized by satisfying the following conditional expression. (10) 28.56 < ωW < 44.11 ωW: half field angle at wide angle end of the variable magnification optical system where ωW = arctan(Y / fW) / 2. Y is the maximum image height at the wide angle end of the variable magnification optical system. fW is the focal length at the wide angle end of the variable magnification optical system.

[0050] The conditional expression (10) is a conditional expression for prescribing an appropriate value for the half field angle at the wide angle end, and relates to the aberration correction ability of the variable magnification optical system.

[0051] If the half field angle at the wide angle end becomes larger than the upper limit of the conditional expression (10), the burden of the off-axis aberration correction borne by the 1st lens group G1 to the 2nd lens group G2 and the 5th lens group G5 to the final lens group GL increases, and in particular, it becomes difficult to correct the non-point aberration at the wide angle end to the telephoto end. If the half field angle at the wide angle end becomes smaller than the lower limit of the conditional expression (10), the burden of the on-axis aberration correction borne by the 2nd lens group G2 to the 4th lens group G4 increases, and in particular, it becomes difficult to correct the spherical aberration at the wide angle end to the telephoto end.

[0052] Further, in order to make the effects of the present application more reliable, the conditional expression (10) preferably has the upper limit value set to 43.38 and the lower limit value set to 29.15, and more preferably has the upper limit value set to 42.65 and the lower limit value set to 29.74.

[0053] In the variable magnification optical system of the present application, a structure is disclosed in which the 4th lens group G4 or the 5th lens group G5 is moved along the optical axis when focusing from the infinity end to the close end, whereby the miniaturization of the variable magnification optical system and the good correction of each aberration in the variable magnification optical system can be achieved at the same time. In the case where the 4th lens group G4 is moved at the time of focusing, it is easy to suppress the variation involved in focusing of the off-axis ray deflection angle borne by the 4th lens group G4, and in particular, it is easy to correct the non-point aberration at the wide angle end. In the case where the 5th lens group G5 is moved at the time of focusing, it is easy to suppress the variation involved in focusing of the on-axis ray deflection angle borne by the 5th lens group G5, and in particular, it is easy to correct the spherical aberration at the telephoto end.

[0054] In the variable magnification optical system of the present application, a structure is disclosed in which the lens surface on the object side in the negative lens L3n disposed most on the image side in the 3rd lens group G3 is in contact with air. Thereby, it is easy to design the refractive index difference before and after this surface, and it is easy to correct the spherical aberration and the on-axis chromatic aberration generated within the 3rd lens group G3.

[0055] In the variable magnification optical system of the present application, a structure is disclosed in which an object side lens surface of a negative lens L4n arranged most on the object side in the 4th lens group G4 is in contact with air. Thereby, the refractive index difference before and after the surface is easily set, and spherical aberration and on-axis chromatic aberration generated in the 4th lens group G4 can be easily corrected.

[0056] In the variable magnification optical system of the present application, a structure is disclosed in which the 1st lens group G1 has at least one negative lens. Thereby, chromatic aberration caused by the 1st lens group G1 can be suppressed, and in particular, magnification chromatic aberration at the telephoto end can be easily corrected.

[0057] In the variable magnification optical system of the present application, a structure is disclosed in which the 3rd lens group G3 has an aperture stop S at a position most on the object side, and the 3rd lens group G3 moves integrally with the aperture stop S when magnification is changed. Thereby, the entrance pupil position of the variable magnification optical system is easily made to approach the object side, the burden of off-axis aberration correction of the 1st lens group G1 to the 2nd lens group G2 can be suppressed, and in particular, non-point aberration at the wide angle end can be easily corrected.

[0058] In the variable magnification optical system of the present application, a structure is disclosed in which the 5th lens group G5 has at least one positive lens. Thereby, chromatic aberration caused by the 5th lens group G5 can be suppressed, and in particular, on-axis chromatic aberration variation at the time of focusing at the wide angle end or even the telephoto end can be easily suppressed.

[0059] In the variable magnification optical system of the present application, a structure is disclosed in which the 2nd lens group G2 is fixed with respect to the image surface when magnification is changed from the wide angle end to the telephoto end. Thereby, the change in lateral magnification assumed by the 2nd lens group G2 and the change in lateral magnification assumed by a lens group arranged more on the image side than the 2nd lens group G2 can be balanced when magnification is changed, and in particular, spherical aberration from the wide angle end to the telephoto end can be easily corrected.

[0060] In the variable magnification optical system of the present application, a structure is disclosed in which the final lens group GL is fixed with respect to the image surface when magnification is changed from the wide angle end to the telephoto end. Thereby, the change in off-axis aberration correction burden assumed by the final lens group GL when magnification is changed can be made linear, and in particular, non-point aberration in the intermediate region can be easily corrected.

[0061] In the variable magnification optical system of the present application, a structure is disclosed in which the 3rd lens group G3 has a vibration isolation lens group having positive refractive power which can move in a direction substantially perpendicular to the optical axis. Image blur correction can be performed by moving the vibration isolation lens group in a direction substantially perpendicular to the optical axis, and thereby the correction burden of each aberration assumed by the vibration isolation lens group at the time of non-vibration isolation can be suppressed, and in particular, by making the sign of the refractive power of the vibration isolation lens group coincide with the sign of the refractive power of the 3rd lens group G3, the burden of magnification of the 3rd lens group G3 as a whole is not hindered, the vibration isolation lens group can be arranged, and aberration correction at the time of vibration isolation and at the time of non-vibration isolation can be easily achieved simultaneously.

[0062] The imaging device of the present application is configured to mount the above-described variable magnification optical system. Thus, an imaging device having a small size, a large aperture ratio of the variable magnification optical system, a high variable magnification ratio, and a good correction of each aberration can be provided.

[0063] Next, the structure of the embodiment of the variable magnification optical system of the present application will be described. In the following description, the lens structure is described in the order from the object side to the image side.

[0064] In the [surface data], the surface number is the number of the lens surface or the aperture stop S counted from the object side, r is the radius of curvature of each surface, d is the vertex interval of each surface, nd is the refractive index for the d line (wavelength 587.56 nm), vd indicates the Abbe number for the d line, and PgF indicates the partial dispersion ratio for the g line (wavelength 435.8 nm) and the F line (wavelength 486.1 nm).

[0065] The * (asterisk) attached to the surface number indicates that the lens surface shape thereof is an aspherical surface. Also, BF indicates the back focal length.

[0066] The (stop) attached to the surface number indicates that the aperture stop S is located at this position. ∞ (infinity) is written in the radius of curvature with respect to the plane or the aperture stop S.

[0067] In the [aspherical surface data], the values of each coefficient of the aspherical surface shape of the lens surface to which the * is assigned in the [surface data] are shown. With respect to the aspherical surface shape, when the displacement from the axial direction to the direction orthogonal to the optical axis is set as y, the displacement (amount of sag) from the intersection of the aspherical surface and the optical axis to the optical axis direction is set as z, the radius of curvature of the reference sphere is set as r, the conic coefficient is set as K, 4, 6,..., and the aspherical surface coefficients of the 20th order are set as A4, A6,..., A20, respectively, the coordinates of the aspherical surface are represented by the following formula. z = (y^2 / r) / [1 + {1-(1+K)×(y / r)^2}]+∑(An×y^n), n = 4, 6,..., 20

[0068] In the [various data], the values of the focal length and the like in the state of each focal length and the zoom ratio are shown.

[0069] In the [variable interval data], the values of the variable interval and the BF in the state of each focal length are shown.

[0070] In the [lens group data], the surface number of the most object side and the composite focal length of the entire group that constitute each lens group are shown.

[0071] Further, in all the following specification values, unless otherwise specified, the units of the focal length f, the curvature radius r, the lens face interval d, and other lengths are in millimeters (mm), but equivalent optical performance can be obtained even in scale-up and scale-down in the optical system, and thus the present application is not limited thereto.

[0072] Further, in the lens configuration diagrams corresponding to each embodiment, the solid arrows indicate the trajectories of the lens groups when zooming from the wide angle end to the telephoto end, the broken arrows with folds indicate the trajectories of the lens groups when focusing from the infinity end to the close end, the broken arrows without folds indicate the trajectories of the lens groups when image blur correction, S is the aperture stop, I is the image plane, and the single-dot broken line through the center is the optical axis.

[0073] Further, in the aberration diagrams corresponding to each embodiment, d, g, C indicate the d-line, the g-line, and the C-line, respectively, and ΔS, ΔM indicate the sagittal image plane and the meridional image plane, respectively. [Embodiment 1]

[0074] Figure 1 is a lens configuration diagram of the zoom optical system of Embodiment 1 of the present application.

[0075] Embodiment 1 is composed of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, which are arranged in order from the object side. Further, the sixth lens group G6 corresponds to the final lens group GL.

[0076] When zooming from the wide angle end to the telephoto end, the interval of the first lens group G1 and the second lens group G2 increases, the interval of the second lens group G2 and the third lens group G3 decreases, the interval of the third lens group G3 and the fourth lens group G4 decreases, the interval of the fourth lens group G4 and the fifth lens group G5 increases, and the interval of the fifth lens group G5 and the sixth lens group G6 increases. Further, the second lens group G2 and the sixth lens group G6 are fixed with respect to the image plane I at the time of zooming.

[0077] When focusing from the infinity end to the close end, the fifth lens group G5 moves toward the image side along the optical axis.

[0078] The first lens group G1 is composed of a negative meniscus lens with the convex surface toward the object side and a biconvex lens, which are joined, and a positive meniscus lens with the convex surface toward the object side, which are arranged in order from the object side.

[0079] The second lens group G2 is composed of a negative meniscus lens with the convex surface toward the object side, a biconcave lens and a biconvex lens, which are joined, and a negative meniscus lens with the convex surface toward the image side, which are arranged in order from the object side.

[0080] The 3rd lens group G3 is composed of an aperture stop S, a biconvex lens, and a negative meniscus lens L3n with a convex surface toward the image side, arranged in this order from the object side.

[0081] The 4th lens group G4 is composed of a biconvex lens, a biconcave lens L4n, and a biconvex lens, arranged in this order from the object side.

[0082] The 5th lens group G5 is composed of a biconvex lens and a biconcave lens, arranged in this order from the object side.

[0083] The 6th lens group G6 is composed of a biconvex lens, a biconcave lens, and a positive meniscus lens with a convex surface toward the object side, arranged in this order from the object side.

[0084] Figure 2A 、 Figure 2B and Figure 2C are longitudinal aberration diagrams at the wide-angle end, the intermediate focal length, and the telephoto end of the infinite object focusing, respectively, involved in the zoom optical system of Example 1. Figure 3A 、 Figure 3B and Figure 3C are lateral aberration diagrams at the wide-angle end, the intermediate focal length, and the telephoto end of the infinite object focusing, respectively, involved in the zoom optical system of Example 1. As is clear from the respective aberration diagrams, the zoom optical system involved in this example is well corrected in terms of each aberration from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0085] Hereinafter, the values of the respective specifications involved in the zoom optical system of Example 1 of the present application are shown. Numerical Example 1 Unit: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Spacing Data] [Lens Group Data] [Example 2]

[0086] Figure 4is a lens configuration diagram involved in the variable magnification optical system of Embodiment 2 of the present application.

[0087] Embodiment 2 is composed of a first lens group Gl having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, which are arranged in order from the object side. In addition, the sixth lens group G6 corresponds to the final lens group GL.

[0088] When zooming from the wide angle end to the telephoto end, the interval between the first lens group Gl and the second lens group G2 increases, the interval between the second lens group G2 and the third lens group G3 decreases, 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, and the interval between the fifth lens group G5 and the sixth lens group G6 increases. In addition, the sixth lens group G6 is fixed with respect to the image plane I at the time of zooming.

[0089] When focusing from the infinity end to the close-up end, the fourth lens group G4 moves toward the object side along the optical axis.

[0090] The first lens group Gl is composed of a negative meniscus lens having the convex surface toward the object side and a positive meniscus lens having the convex surface toward the object side which are joined together, and a positive meniscus lens having the convex surface toward the object side, which are arranged in order from the object side.

[0091] The second lens group G2 is composed of a negative meniscus lens having the convex surface toward the object side, a double concave lens and a double convex lens which are joined together, and a negative meniscus lens having the convex surface toward the image side, which are arranged in order from the object side.

[0092] The third lens group G3 is composed of the aperture stop S, a double convex lens, and a negative meniscus lens L3n having the convex surface toward the image side, which are arranged in order from the object side.

[0093] The fourth lens group G4 is composed of a double convex lens, a double concave lens L4n and a double convex lens which are joined together, and a positive meniscus lens having the convex surface toward the image side, which are arranged in order from the object side.

[0094] The fifth lens group G5 is composed of a double convex lens and a double concave lens which are joined together, which are arranged in order from the object side.

[0095] The sixth lens group G6 is composed of a double convex lens, a double concave lens and a positive meniscus lens having the convex surface toward the object side which are joined together, which are arranged in order from the object side.

[0096] Figure 5A , Figure 5B and Figure 5CLongitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, of the zoom optical system according to Example 2. Figure 6A , Figure 6B and Figure 6C Longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, of the zoom optical system according to Example 2. As is apparent from the respective aberration diagrams, the zoom optical system according to the present embodiment is favorably corrected in terms of each aberration from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0097] Hereinafter, each specification value of the zoom optical system according to Example 2 of the present embodiment is shown. Numerical Example 2 Unit: mm [Surface data] [Aspherical surface data] [Various data] [Variable interval data] [Group data] [Example 3]

[0098] Figure 7 is a lens configuration diagram of the zoom optical system according to Example 3 of the present embodiment.

[0099] Example 3 is composed of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, which are arranged in this order from the object side. In addition, the sixth lens group G6 corresponds to the final lens group GL.

[0100] 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 increases, the interval between the second lens group G2 and the third lens group G3 decreases, 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 is constant, and the interval between the fifth lens group G5 and the sixth lens group G6 increases. In addition, the sixth lens group G6 is fixed with respect to the image plane I at the time of zooming.

[0101] When focusing from the infinity end to the close end, the 5th lens group G5 moves toward the image side along the optical axis.

[0102] The 1st lens group G1 is composed of a negative meniscus lens having a convex surface toward the object side, a positive meniscus lens having a convex surface toward the object side, and a positive meniscus lens having a convex surface toward the object side, which are arranged in this order from the object side.

[0103] The 2nd lens group G2 is composed of a negative meniscus lens having a convex surface toward the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens having a convex surface toward the image side, which are arranged in this order from the object side.

[0104] The 3rd lens group G3 is composed of an aperture stop S, a biconvex lens, and a biconcave lens L3n and a biconvex lens, which are arranged in this order from the object side.

[0105] The 4th lens group G4 is composed of a biconvex lens, a biconcave lens L4n and a biconvex lens, and a biconvex lens, which are arranged in this order from the object side.

[0106] The 5th lens group G5 is composed of a biconvex lens and a biconcave lens, which are arranged in this order from the object side.

[0107] The 6th lens group G6 is composed of a biconvex lens, a positive meniscus lens having a convex surface toward the image side, and a biconcave lens, which are arranged in this order from the object side.

[0108] Figure 8A 、 Figure 8B and Figure 8C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, in the zoom optical system according to Embodiment 3. Figure 9A 、 Figure 9B and Figure 9C are lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, in the zoom optical system according to Embodiment 3. As is apparent from the respective aberration diagrams, the zoom optical system according to this embodiment is favorably corrected in terms of each aberration from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0109] Hereinafter, each specification value involved in the zoom optical system according to Embodiment 3 will be shown. Numerical Example 3 Unit: mm [Surface Data] [Aspherical Surface Data] [Various data] [Variable interval data] [Group data] [Example 4]

[0110] Figure 10 is a lens configuration diagram of a zoom optical system of Example 4 of the present application.

[0111] Example 4 is composed of a 1st lens group G1 having positive refractive power, a 2nd lens group G2 having negative refractive power, an aperture stop S, a 3rd lens group G3 having positive refractive power, a 4th lens group G4 having positive refractive power, a 5th lens group G5 having negative refractive power, and a 6th lens group G6 having negative refractive power, which are arranged in order from the object side. In addition, the 6th lens group G6 corresponds to the final lens group GL.

[0112] When zooming from the wide-angle end to the telephoto end, the interval of the 1st lens group G1 and the 2nd lens group G2 increases, the interval of the 2nd lens group G2 and the 3rd lens group G3 decreases, the interval of the 3rd lens group G3 and the 4th lens group G4 decreases, the interval of the 4th lens group G4 and the 5th lens group G5 decreases, and the interval of the 5th lens group G5 and the 6th lens group G6 increases. In addition, the 2nd lens group G2 and the 6th lens group G6 are fixed with respect to the image plane I at the time of zooming.

[0113] When focusing from the infinity end to the close-up end, the 5th lens group G5 moves toward the image side along the optical axis.

[0114] The 1st lens group G1 is composed of a negative meniscus lens with the convex surface facing the object side and a biconvex lens, which are arranged in order from the object side, and a positive meniscus lens with the convex surface facing the object side.

[0115] The 2nd lens group G2 is composed of a negative meniscus lens with the convex surface facing the object side, a biconcave lens and a biconvex lens, which are arranged in order from the object side, and a negative meniscus lens with the convex surface facing the image side.

[0116] The 3rd lens group G3 is composed of the aperture stop S, a biconvex lens, a biconvex lens, and a negative meniscus lens L3n with the convex surface facing the image side, which are arranged in order from the object side.

[0117] The 4th lens group G4 is composed of a biconvex lens, a biconcave lens L4n and a biconvex lens, which are arranged in order from the object side, and a biconvex lens.

[0118] The 5th lens group G5 is composed of a double convex lens and a double concave lens arranged in this order from the object side.

[0119] The 6th lens group G6 is composed of a negative meniscus lens having a convex surface toward the object side and a positive meniscus lens having a convex surface toward the image side arranged in this order from the object side.

[0120] Figure 11A 、 Figure 11B and Figure 11C are longitudinal aberration diagrams at the time of focusing on an infinite distant object at the wide angle end, the intermediate focal length, and the telephoto end, respectively, of the zoom optical system according to Embodiment 4. Figure 12A 、 Figure 12B and Figure 12C are lateral aberration diagrams at the time of focusing on an infinite distant object at the wide angle end, the intermediate focal length, and the telephoto end, respectively, of the zoom optical system according to Embodiment 4. As is apparent from the respective aberration diagrams, the zoom optical system according to this embodiment is well corrected in terms of each aberration from the wide angle end to the telephoto end, and has excellent imaging performance.

[0121] Hereinafter, each specification value of the zoom optical system according to Embodiment 4 of the present application will be shown. Numerical Embodiment 4 Unit: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Interval Data] [Lens Group Data] [Embodiment 5]

[0122] Figure 13 is a lens configuration diagram of the zoom optical system according to Embodiment 5 of the present application.

[0123] Embodiment 5 is composed of a 1st lens group G1 having positive refractive power, a 2nd lens group G2 having negative refractive power, an aperture stop S, a 3rd lens group G3 having positive refractive power, a 4th lens group G4 having positive refractive power, a 5th lens group G5 having negative refractive power, and a 6th lens group G6 having negative refractive power arranged in this order from the object side. In addition, the 6th lens group G6 corresponds to the final lens group GL.

[0124] 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 increases, the interval between the second lens group G2 and the third lens group G3 decreases, 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 increases, and the interval between the fifth lens group G5 and the sixth lens group G6 increases. In addition, the sixth lens group G6 is fixed relative to the image plane I during zooming.

[0125] When focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0126] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens with the convex surface facing the object side and a biconvex lens, and a positive meniscus lens with the convex surface facing the object side.

[0127] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens with the convex surface facing the object side, a biconcave lens and a biconvex lens, and a negative meniscus lens with the convex surface facing the image side.

[0128] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a biconvex lens and a negative meniscus lens with the convex surface facing the image side, and a biconcave lens L3n and a biconvex lens.

[0129] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a biconcave lens L4n and a biconvex lens, and a biconvex lens.

[0130] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens and a biconcave lens.

[0131] The sixth lens group G6 is composed of, in order from the object side, a negative meniscus lens with the convex surface facing the object side, a biconvex lens and a biconcave lens.

[0132] Figure 14A 、 Figure 14B and Figure 14C are longitudinal aberration diagrams at the time of focusing on an infinite object at the wide angle end, the intermediate focal length, and the telephoto end, respectively, involved in Embodiment 5. Figure 15A 、 Figure 15B and Figure 15C are transverse aberration diagrams at the time of focusing on an infinite object at the wide angle end, the intermediate focal length, and the telephoto end, respectively, involved in Embodiment 5. As is apparent from each of the aberration diagrams, the zoom optical system involved in this embodiment is well corrected in each aberration from the wide angle end to the telephoto end, and has excellent imaging performance.

[0133] The following shows the values of the various specifications relating to the variable magnification optical system of Embodiment 5 of the present application. Numerical Embodiment 5 Units: mm [Surface Data] [Aspherical Surface Data] [Various Data] [Variable Spacing Data] [Lens Group Data] [Embodiment 6]

[0134] Figure 16 is a lens configuration diagram of the variable magnification optical system of Embodiment 6 of the present application.

[0135] Embodiment 6 is composed of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power, which are arranged in order from the object side. In addition, the fifth lens group G5 corresponds to the final lens group GL.

[0136] When magnification is changed from the wide angle end to the telephoto end, the spacing between the first lens group G1 and the second lens group G2 increases, the spacing between the second lens group G2 and the third lens group G3 decreases, the spacing between the third lens group G3 and the fourth lens group G4 decreases, and the spacing between the fourth lens group G4 and the fifth lens group G5 increases.

[0137] When focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0138] The first lens group G1 is composed of a negative meniscus lens having the convex surface facing the object side, a positive meniscus lens having the convex surface facing the object side, and a positive meniscus lens having the convex surface facing the object side, which are arranged in order from the object side.

[0139] The second lens group G2 is composed of a negative meniscus lens having the convex surface facing the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens having the convex surface facing the image side, which are arranged in order from the object side.

[0140] The 3rd lens group G3 is composed of an aperture stop S, a biconvex lens, a biconvex lens and a negative meniscus lens with the convex surface facing the image side, and a negative meniscus lens L3n with the convex surface facing the image side, arranged in order from the object side.

[0141] The 4th lens group G4 is composed of a biconvex lens, a biconcave lens L4n and a biconvex lens, arranged in order from the object side.

[0142] The 5th lens group G5 is composed of a biconvex lens and a biconcave lens, arranged in order from the object side.

[0143] Figure 17A Figure 17B Figure 17C are longitudinal aberration diagrams of the wide-angle end, the intermediate focal length and the telephoto end of the infinity object focusing of the embodiment 6, respectively. Figure 18A Figure 18B Figure 18C are lateral aberration diagrams of the wide-angle end, the intermediate focal length and the telephoto end of the infinity object focusing of the embodiment 6, respectively. It can be seen from the aberration diagrams that the zoom optical system of the embodiment 6 is well corrected in each aberration from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0144] The following shows the specification values of the embodiment 6 of the present application. Numerical example 6 Unit: mm [Surface data] [Aspherical surface data] [Various data] [Variable interval data] [Lens group data] [Example 7]

[0145] Figure 19 is the lens structure diagram of the embodiment 7 of the present application.

[0146] ​​​​Embodiment 7 is composed of a first lens group Gl having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power, which are arranged in this order from the object side. In addition, the sixth lens group G6 corresponds to the final lens group GL.

[0147] When zooming from the wide-angle end to the telephoto end, the interval between the first lens group Gl and the second lens group G2 increases, the interval between the second lens group G2 and the third lens group G3 decreases, 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 increases, and the interval between the fifth lens group G5 and the sixth lens group G6 increases. In addition, the sixth lens group G6 is fixed with respect to the image plane I at the time of zooming.

[0148] When focusing from the infinity end to the close-up end, the fifth lens group G5 moves toward the image side along the optical axis.

[0149] The first lens group Gl is composed of a negative meniscus lens with the convex surface facing the object side and a biconvex lens, which are joined, and a positive meniscus lens with the convex surface facing the object side, which are arranged in this order from the object side.

[0150] The second lens group G2 is composed of a negative meniscus lens with the convex surface facing the object side, a biconcave lens and a biconvex lens, which are joined, and a negative meniscus lens with the convex surface facing the image side, which are arranged in this order from the object side.

[0151] The third lens group G3 is composed of the aperture stop S, a biconvex lens, and a biconvex lens and a negative meniscus lens L3n with the convex surface facing the image side, which are joined, which are arranged in this order from the object side.

[0152] The fourth lens group G4 is composed of a biconvex lens, a biconcave lens L4n and a biconvex lens, which are joined, and a positive meniscus lens with the convex surface facing the image side, which are arranged in this order from the object side.

[0153] The fifth lens group G5 is composed of a biconvex lens and a biconcave lens, which are joined, which are arranged in this order from the object side.

[0154] The sixth lens group G6 is composed of a biconvex lens, and a biconvex lens and a biconcave lens, which are joined, which are arranged in this order from the object side.

[0155] Figure 20A , Figure 20B and Figure 20C are longitudinal aberration diagrams at the time of focusing on an infinite distant object at the wide-angle end, the intermediate focal distance, and the telephoto end, respectively, involved in Embodiment 7. Figure 21A , Figure 21B and Figure 21CThe lateral aberration diagrams at the time of focusing on an infinite object at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, involved in Example 7. As is apparent from each of the aberration diagrams, the variable magnification optical system involved in this example is well corrected for each aberration from the wide-angle end to the telephoto end, and has excellent imaging performance.

[0156] The following shows the specification values involved in Example 7 of the present application. Numerical Example 7 Units: mm [Surface data] [Aspheric surface data] [Various data] [Variable interval data] [Lens group data] [Example 8]

[0157] Figure 22 is a lens configuration diagram of Example 8 of the present application.

[0158] Example 8 is composed of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power, which are arranged in this order from the object side. In addition, the seventh lens group G7 corresponds to the final lens group GL.

[0159] When magnification is changed from the wide-angle end to the telephoto end, the interval between the first lens group G1 and the second lens group G2 increases, the interval between the second lens group G2 and the third lens group G3 decreases, 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, and the interval between the sixth lens group G6 and the seventh lens group G7 increases. The seventh lens group G7 is fixed with respect to the image plane I at the time of magnification change.

[0160] When focusing from the infinite end to the closest end, the fifth lens group G5 moves toward the image side along the optical axis.

[0161] The first lens group G1 is composed of a negative meniscus lens with the convex surface facing the object side and a biconvex lens, and a positive meniscus lens with the convex surface facing the object side, which are arranged in this order from the object side.

[0162] The second lens group G2 is composed of a negative meniscus lens with the convex surface facing the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with the convex surface facing the image side, which are arranged in this order from the object side.

[0163] The third lens group G3 is composed of an aperture stop S, a biconvex lens, a negative meniscus lens with the convex surface facing the object side and a biconvex lens, and a negative meniscus lens L3n with the convex surface facing the image side, which are arranged in this order from the object side. When the image blur occurs, the negative meniscus lens with the convex surface facing the object side and the biconvex lens of the second and third lenses from the object side of the third lens group G3 are moved in a direction substantially perpendicular to the optical axis.

[0164] The fourth lens group G4 is composed of a biconvex lens, a biconcave lens L4n and a biconvex lens, and a biconvex lens, which are arranged in this order from the object side.

[0165] The fifth lens group G5 is composed of a biconvex lens and a biconcave lens, which are arranged in this order from the object side.

[0166] The sixth lens group G6 is composed of a negative meniscus lens with the convex surface facing the object side and a positive meniscus lens with the convex surface facing the object side, which are arranged in this order from the object side.

[0167] The seventh lens group G7 is composed of a biconcave lens.

[0168] Figure 23A 、 Figure 23B and Figure 23C are longitudinal aberration diagrams when an object at infinity is focused at the wide angle end, the intermediate focal length and the telephoto end, respectively, in the zoom optical system according to Embodiment 8. Figure 24A 、 Figure 24B and Figure 24C are lateral aberration diagrams when an object at infinity is focused at the wide angle end, the intermediate focal length and the telephoto end, respectively, in the zoom optical system according to Embodiment 8. Figure 25A 、 Figure 25B and Figure 25C are lateral aberration diagrams when an object at infinity is focused at the wide angle end, the intermediate focal length and the telephoto end, respectively, in the zoom optical system according to Embodiment 8, in which the image blur correction of 0.3° is performed. As is apparent from the aberration diagrams, the zoom optical system according to Embodiment 8 has excellent imaging performance because each aberration is well corrected from the wide angle end to the telephoto end.

[0169] Hereinafter, the specification values according to Embodiment 8 of the present application are shown. Numerical Example 8 Unit: mm [Surface data] [Aspherical surface data] [Various data] [Variable interval data] [Lens group data]

[0170] Next, a camera having the variable magnification optical system of the present application will be described. Figure 26 A camera having the variable magnification optical system of the present application will be described.

[0171] In Figure 26 , 1 is a camera, 2 is the variable magnification optical system of any one of Embodiments 1 to 8, and 3 is an imaging section built in the camera 1. The camera 1 includes an image processing engine and the like not shown, and the imaging section 3 includes a cover glass or an optical low-pass filter and the like not shown, and an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor. An object (subject) not shown forms an image (subject image) in the imaging section 3 through the variable magnification optical system 2, and the camera 1 records the image (subject image) in a memory not shown.

[0172] Thus, a photographer can take a photograph of a subject using a camera having the variable magnification optical system, which is small, can realize a large aperture ratio and a high magnification ratio of the variable magnification optical system, and each aberration is well corrected.

[0173] Next, Table 1 below shows the aberration characteristics of the embodiments (1 to 8) related to the variable magnification optical system of the present application and the conditional expression correspondence values of these variable magnification optical systems. Also, Table 2 below shows the aberration characteristics of the variable magnification optical systems of the comparative examples and the conditional expression correspondence values of these variable magnification optical systems. In addition, the various numerical values related to the comparative examples A to C described in Table 2 are calculated using the embodiments described in Non-Patent Documents 1 to 3.

[0174] [Table 1]

[0175] [Table 2]

[0176] The various aberration coefficients shown in Table 1 and Table 2 are calculated by the calculation method described in Non-Patent Literature 1 and Non-Patent Literature 2. The technical meaning of the aberration coefficients is that the relationship between the structure of the optical system and the limit of the aberration and the aberration correction capability can be explicitly expressed. In addition, among the aberration coefficients, there are methods of expressing the component of the lateral aberration on the paraxial image plane or methods of normalizing the component of the lateral aberration on the paraxial image plane with respect to the aperture and the field angle. Here, the aberration coefficients are calculated by the calculation method described in Non-Patent Literature 2 based on "Improvement of Normalization (2)". Even if the focal length, NA, and ideal image height of the zoom optical system are various, this calculation method is effective as an evaluation means when the performance of the optical system is compared with each other. In addition, in Table 1 and Table 2, the aberration coefficients are evaluated for both the wide-angle end and the telephoto end, and with respect to chromatic aberration, the evaluation is finally performed in a single manner by taking the root sum square (RSS) of them at multiple wavelengths. The final evaluation of the examples and comparative examples is divided into three stages, and is evaluated by the following methods, respectively. The on-axis chromatic aberration is ○: RSS(L) < 0.0040, Δ: 0.0040 ≤ RSS(L) < 0.0070, and ×: RSS(L) ≥ 0.0070. The magnification chromatic aberration is ○: RSS(T) < 0.0020, Δ: 0.0020 ≤ RSS(T) < 0.0035, and ×: RSS(T) ≥ 0.0035. The spherical aberration is ○: RSS(I) < 0.4000, Δ: 0.4000 ≤ RSS(I) < 0.8000, and ×: RSS(I) ≥ 0.8000. The coma aberration is ○: RSS(II) < 0.0400, Δ: 0.0400 ≤ RSS(II) < 0.0800, and ×: RSS(II) ≥ 0.0800. The non-point aberration is ○: RSS(III) < 0.0040, Δ: 0.0040 ≤ RSS(III) < 0.0080, and ×: RSS(III) ≥ 0.0080. As can be seen from Table 1 and Table 2, in the examples of the zoom optical system according to the present application, various aberrations are well corrected from the wide-angle end to the telephoto end.

[0177] The following can be appropriately adopted within a range that does not impair the imaging performance of the zoom optical system according to the present application.

[0178] As an example of the variable magnification optical system, a variable magnification optical system of a 5-group, 6-group, and 7-group structure is shown, but is not limited thereto, and can be configured as a structure of another group number (for example, 8 groups or 9 groups, etc.). Specifically, a structure in which a planar optical filter or lens group is added to the position of the most object side or the most image side of the variable magnification optical system can also be used. In addition, the lens group refers to a portion having at least one lens that is separated at a varying interval when magnification is changed from the wide angle end to the telephoto end.

[0179] Generally, if it is a planar optical member or a lens group having a sufficiently weak refractive power compared to the focal length at the wide angle end, even if the optical system is added, the impact on the aberration correction is minimal and can be ignored, or even if the impact on the aberration correction is caused by adding the optical system, only a small change in the refractive power configuration of the optical system is required, and the skeleton of the optical system is not affected.

[0180] As an example of the variable magnification optical system, a variable magnification optical system having all lens surfaces with refractive power as curved surfaces and a refractive surface is shown, but is not limited thereto, and a refractive index distribution type material, a metasurface, and a diffractive optical element can be used for planar or curved surfaces. Specifically, if the variable magnification optical system of the present application is taken as an example, if the object side lens surface of the negative lens L3n disposed on the most image side in the 3rd lens group G3 is set as a diffractive surface, even if the surface is made convex toward the object side, the same effect as the present application can be obtained. Also, if the object side lens surface of the negative lens L4n disposed on the most object side in the 4th lens group G4 is set as a diffractive surface, even if the surface is made convex toward the object side, the same effect as the present application can be obtained.

[0181] An anti-reflection film can be applied to the lens surface constituting the variable magnification optical system. Thereby, it is possible to reduce flare or ghosting, and a higher contrast image can be obtained.

[0182] In addition, the focal length of the above variable magnification optical system or lens group, the back focal length of the variable magnification optical system, the movement amount of the lens group, the refractive index, the Abbe number, the partial dispersion ratio, and the half field angle of the variable magnification optical system can each be set to a value measured by the following method.

[0183] The focal length of the variable magnification optical system or lens group can be measured by following JIS B 7094 (Photographic lenses - Method of measurement of focal length). Specifically, the lens under test is set on a holding portion mounted on a focal length measuring device that can be implemented by any of Measurement Method 1 to Measurement Method 4 described in the standard, and measurement is performed. As examples of the focal length measuring device, there are the MB series manufactured by Pearl Optical Co., Ltd. (Measurement Method 3) or the OptiSpheric series manufactured by Trioptics GmbH (Measurement Method 1).

[0184] The back focal length of the variable magnification optical system can be measured by using a commercially available back focal length measuring device. Specifically, the lens under test is set on a holding portion mounted on the measuring device, and measurement is performed. As examples of the back focal length measuring device, there are the MB series manufactured by Pearl Optical Co., Ltd. or the OptiSpheric series manufactured by Trioptics GmbH.

[0185] The movement amount of the lens group can be measured by using a commercially available surface interval measuring device. Specifically, the lens under test is set on a holding portion mounted on the measuring device, and measurement is performed. As examples of the surface interval measuring device, there is the OptiSurf series manufactured by Trioptics GmbH.

[0186] The refractive index, Abbe number, and partial dispersion ratio can be measured by following JIS B 7071 (Optics and photonics - Method of measurement of refractive index of optical glass) or JIS K 7142 (Plastics - Method of determination of refractive index). Specifically, the lens under test is processed into a shape that can be set on a holding portion mounted on a refractive index measuring device that can be implemented by any of the measurement methods (V-block method, minimum deflection angle method, A method for plastics) described in the standards, and the measurement wavelength is changed for each respective spectral line, and measurement is performed. As examples of the refractive index measuring device, there are the KPR series manufactured by Shimadzu Corporation (V-block method) or the GMR series manufactured by Shimadzu Corporation (minimum deflection angle method).

[0187] The half field angle of the variable magnification optical system can be measured by following Non-Patent Literature 3. Specifically, first, the photograph taken by the variable magnification optical system is directly observed by the naked eye, and the image circle diameter Φ is measured by a measuring tool such as a caliper. Next, the focal length f obtained in the measurement described in the fourth paragraph is used to find the half field angle ω = arctan((Φ / 2) / f) / 2.

[0188] The above describes the configuration of the embodiment of the variable magnification optical system according to the present application, but the present application is not limited to the above-described embodiment and can be variously modified. The shape and numerical value of each part shown in the above-described numerical example are one example of implementing the present technology, and the technical scope of the present application is not to be construed limitatively by these examples.

[0189] The above embodiment can take the following configuration. [Item 1] A variable magnification optical system characterized by comprising: a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power, which are arranged in order from an object side, when magnifying from a wide angle end to a telephoto end, the interval between the first lens group G1 and the second lens group G2 changes, the interval between the second lens group G2 and the third lens group G3 changes, and the interval between the third lens group G3 and the fourth lens group G4 changes, when focusing from an infinity end to a close-up end, any one of the fourth lens group G4 and the fifth lens group G5 moves along an optical axis, the third lens group G3 has at least one negative lens, and the lens surface of the negative lens L3n arranged closest to an image side in the third lens group G3 protrudes toward an image side from an object side, the fourth lens group G4 has at least one negative lens, and the lens surface of the negative lens L4n arranged closest to an object side in the fourth lens group G4 protrudes toward an image side from an object side, the variable magnification optical system satisfies the following conditional expressions, (1) 0.61 < f34 / fW < 1.46 (2) 0.32 < f4 / f3 < 0.96 (3) -0.0085 < ΔPgF1 + ΔPgF2 < 0.0070 f34: the combined focal length of the third lens group G3 to the fourth lens group G4, where f34 = 1 / (∑(1 / fn)), n = 3-4, fn is the focal length of the nth lens group fW: the focal length at the wide angle end of the variable magnification optical system f4: the focal length of the fourth lens group G4 f3: the focal length of the third lens group G3 ΔPgF1: abnormal dispersion of a negative lens L3n arranged closest to the image side in the third lens group G3, where ΔPgF1 = PgF1 - 0.64833 + 0.00180 x vd1, PgF1 is a partial dispersion ratio for g-line and F-line of the negative lens L3n arranged closest to the image side in the third lens group G3, and vd1 is an Abbe number for d-line of the negative lens L3n arranged closest to the image side in the third lens group G3, ΔPgF2: abnormal dispersion of a negative lens L4n arranged closest to the object side in the fourth lens group G4, where ΔPgF2 = PgF2 - 0.64833 + 0.00180 x vd2, PgF2 is a partial dispersion ratio for g-line and F-line of the negative lens L4n arranged closest to the object side in the fourth lens group G4, and vd2 is an Abbe number for d-line of the negative lens L4n arranged closest to the object side in the fourth lens group G4. [Item 2] The variable magnification optical system according to [Item 1], characterized in that the following conditional expression is also satisfied, (4) 0.13 < |f13| / f4L < 1.25 f13: combined focal length of the first lens group G1 to the third lens group G3, where f13 = 1 / (∑(1 / fn)), n = 1 to 3, and fn is a focal length of the nth lens group, f4L: combined focal length of the fourth lens group G4 to a lens group arranged closest to the image side (hereinafter, final lens group GL), where f4L = 1 / (∑(1 / fn)), n = 4 to L, fn is a focal length of the nth lens group, and fL is a focal length of the final lens group GL. [Item 3] The variable magnification optical system according to [Item 1] or [Item 2], characterized in that the following conditional expression is also satisfied, (5) 1.12 < m4 / m3 < 1.56 m4: movement amount of the fourth lens group G4 when magnification is changed from the wide-angle end to the telephoto end (movement to the object side is taken as positive) m3: movement amount of the third lens group G3 when magnification is changed from the wide-angle end to the telephoto end (movement to the object side is taken as positive) [Item 4] The variable magnification optical system according to any one of [Item 1] to [Item 3], characterized in that the following conditional expression is also satisfied, (6) 1.17 < |f5| / f4 < 2.89 f5: focal length of the fifth lens group G5 f4: focal length of the fourth lens group G4. [Item 5] The variable magnification optical system according to any one of [Item 1] to [Item 4], further satisfies the following conditional expression, (7) 0.83 < m5 / m4 < 1.24 m5: moving amount of the fifth lens group G5 when magnification is changed from the wide angle end to the telephoto end (movement to the object side is taken as positive) m4: moving amount of the fourth lens group G4 when magnification is changed from the wide angle end to the telephoto end (movement to the object side is taken as positive). [Item 6] The variable magnification optical system according to any one of [Item 1] to [Item 5], further satisfies the following conditional expression, (8) 1.34 < |f5L| / fW < 4.25 f5L: composite focal length of the fifth lens group G5 to a lens group disposed most on the image side (hereinafter, final lens group GL), where f5L = 1 / (∑(1 / fn)), n = 5 to L, fn is the focal length of the nth lens group, and fL is the focal length of the final lens group GL, fW: focal length at the wide angle end of the variable magnification optical system. [Item 7] The variable magnification optical system according to any one of [Item 1] to [Item 6], further satisfies the following conditional expression, (9) 0.51 < bfW / fW < 1.85 bfW: back focal length at the wide angle end of the variable magnification optical system fW: focal length at the wide angle end of the variable magnification optical system. [Item 8] The variable magnification optical system according to any one of [Item 1] to [Item 7], further satisfies the following conditional expression, (10) 28.56 < ωW < 44.11 ωW: half field angle at the wide angle end of the variable magnification optical system, where ωW = arctan(Y / f W) / 2, Y is the maximum image height at the wide angle end of the variable magnification optical system, and fW is the focal length at the wide angle end of the variable magnification optical system. [Item 9] The variable magnification optical system according to any one of [Item 1] to [Item 8], wherein, the fourth lens group G4 moves to the object side along the optical axis when focusing from the infinity end to the close end. [Item 10] The variable magnification optical system according to any one of [Item 1] to [Item 9], characterized in that, When focusing from the infinity end to the close end, the 5th lens group G5 moves toward the object side along the optical axis. [Item 11] The variable magnification optical system according to any one of [Item 1] to [Item 10], characterized in that, The lens surface on the object side in the negative lens L3n disposed most on the image side in the 3rd lens group G3 is in contact with air. [Item 12] The variable magnification optical system according to any one of [Item 1] to [Item 11], characterized in that, The lens surface on the object side in the negative lens L4n disposed most on the object side in the 4th lens group G4 is in contact with air. [Item 13] The variable magnification optical system according to any one of [Item 1] to [Item 12], characterized in that, The 1st lens group G1 has at least one negative lens. [Item 14] The variable magnification optical system according to any one of [Item 1] to [Item 13], characterized in that, An aperture stop S is provided at a position most on the object side of the 3rd lens group G3, and the 3rd lens group G3 moves integrally with the aperture stop S when magnification is changed. [Item 15] The variable magnification optical system according to any one of [Item 1] to [Item 14], characterized in that, The 5th lens group G5 has at least one positive lens. [Item 16] The variable magnification optical system according to any one of [Item 1] to [Item 15], characterized in that, The 2nd lens group G2 is fixed with respect to the image plane when magnification is changed from the wide angle end to the telephoto end. [Item 17] The variable magnification optical system according to any one of [Item 1] to [Item 16], characterized in that, The lens group disposed most on the image side (hereinafter, final lens group (GL)) is fixed with respect to the image plane when magnification is changed from the wide angle end to the telephoto end. [Item 18] The variable magnification optical system according to any one of [Item 1] to [Item 17], characterized in that, The third lens group G3 has a positive refractive power vibration isolation lens group capable of moving in a direction substantially perpendicular to the optical axis. [Item 19] An image pickup apparatus incorporating the variable magnification optical system according to any one of [Item 1] to [Item 18]. Symbol explanation

[0190] G1 - first lens group, G2 - second lens group, G3 - third lens group, G4 - fourth lens group, G5 - fifth lens group, G6 - sixth lens group, G7 - seventh lens group, GL - final lens group, L3n - negative lens disposed most on the image side in the third lens group G3, L4n - negative lens disposed most on the object side in the fourth lens group G4, S - aperture stop, I - image plane.

Claims

1. A variable magnification optical system characterized by comprising, in order from an object side, a first lens group (Gl) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, a fourth lens group (G4) having positive refractive power, and a fifth lens group (G5) having negative refractive power, a distance between the first lens group (Gl) and the second lens group (G2) changes, a distance between the second lens group (G2) and the third lens group (G3) changes, and a distance between the third lens group (G3) and the fourth lens group (G4) changes when magnification is changed from a wide angle end to a telephoto end, either the fourth lens group (G4) or the fifth lens group (G5) moves along an optical axis when focusing is performed from an infinity end to a close-up end, the third lens group (G3) has at least one negative lens, and a lens surface on an object side of a negative lens (L3n) disposed closest to an image side in the third lens group (G3) is convex toward an image side, the fourth lens group (G4) has at least one negative lens, and a lens surface on an object side of a negative lens (L4n) disposed closest to an object side in the fourth lens group (G4) is convex toward an image side, the variable magnification optical system satisfies the following conditional expressions, (1) 0.61 < f34 / fw < 1.46 (2) 0.32 < f4 / f3 < 0.96 (3) -0.0085 < ΔPgFl + ΔPgF2 < 0.0070 f34 is a composite focal length of the third lens group (G3) to the fourth lens group (G4), where f34 = 1 / (∑(1 / fn)), n = 3 to 4, fn is a focal length of the nth lens group, fw is a focal length at the wide angle end of the variable magnification optical system, f4 is a focal length of the fourth lens group (G4), f3 is a focal length of the third lens group (G3), ΔPgFl is abnormal dispersion of the negative lens (L3n) disposed closest to the image side in the third lens group (G3), where ΔPgFl = PgFl - 0.64833 + 0.00180 x vd1, PgFl is a partial dispersion ratio for g-line and F-line of the negative lens (L3n) disposed closest to the image side in the third lens group (G3), and vd1 is an Abbe number for d-line of the negative lens (L3n) disposed closest to the image side in the third lens group (G3), ΔPgF2 is abnormal dispersion of the negative lens (L4n) disposed closest to the object side in the fourth lens group (G4), where ΔPgF2 = PgF2 - 0.64833 + 0.00180 x vd2, PgF2 is a partial dispersion ratio for g-line and F-line of the negative lens (L4n) disposed closest to the object side in the fourth lens group (G4), and vd2 is an Abbe number for d-line of the negative lens (L4n) disposed closest to the object side in the fourth lens group (G4).

2. The variable magnification optical system according to claim 1, characterized in that the following conditional expression is satisfied, (4) 0.13 < |f13| / f4L < 1.25 ​ ​ f13 is a composite focal length of the first lens group (G1) to the third lens group (G3), where f13 = 1 / (∑(1 / fn)), n = 1 to 3, fn is a focal length of the nth lens group, f4L is a composite focal length of the fourth lens group (G4) to a lens group disposed most on the image side, that is, a final lens group (GL), where f4L = 1 / (∑(1 / fn)), n = 4 to L, fn is a focal length of the nth lens group, and fL is a focal length of the final lens group (GL).

3. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (5) 1.12 < m4 / m3 < 1.56 m4 is a movement amount of the fourth lens group (G4) when magnification is changed from the wide angle end to the telephoto end, where movement to the object side is taken as positive, m3 is a movement amount of the third lens group (G3) when magnification is changed from the wide angle end to the telephoto end, where movement to the object side is taken as positive.

4. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (6) 1.17 < |f5| / f4 < 2.89 f5 is a focal length of the fifth lens group (G5), f4 is a focal length of the fourth lens group (G4).

5. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (7) 0.83 < m5 / m4 < 1.24 m5 is a movement amount of the fifth lens group (G5) when magnification is changed from the wide angle end to the telephoto end, where movement to the object side is taken as positive, m4 is a movement amount of the fourth lens group (G4) when magnification is changed from the wide angle end to the telephoto end, where movement to the object side is taken as positive.

6. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (8) 1.34 < |f5L| / fW < 4.25 f5L is a composite focal length of the fifth lens group (G5) to a lens group disposed most on the image side, that is, a final lens group (GL), where f5L = 1 / (∑(1 / fn)), n = 5 to L, fn is a focal length of the nth lens group, and fL is a focal length of a lens group disposed most on the image side, that is, the final lens group (GL), fW is a focal length at the wide angle end of the variable magnification optical system.

7. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (9) 0.51 < bfW / fW < 1.85 bfW is a back focal length at the wide angle end of the variable magnification optical system, fW is a focal length at the wide angle end of the variable magnification optical system.

8. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied, (10) 28.56 < ωW < 44.11 ωW is a half field angle at the wide angle end of the variable magnification optical system, where ωW = arctan(Y / fW) / 2, Y is a maximum image height at the wide angle end of the variable magnification optical system, and fW is a focal length at the wide angle end of the variable magnification optical system.

9. The variable magnification optical system according to claim 1, wherein When focusing from the infinity end to the close end, the 4th lens group (G4) moves toward the object side along the optical axis.

10. The variable power optical system according to claim 1, wherein When focusing from the infinity end to the close end, the 5th lens group (G5) moves toward the image side along the optical axis.

11. The variable power optical system according to claim 1, wherein The object side lens surface of the negative lens (L3n) disposed closest to the image side in the 3rd lens group (G3) is in contact with air.

12. The variable power optical system according to claim 1, wherein The object side lens surface of the negative lens (L4n) disposed closest to the object side in the 4th lens group (G4) is in contact with air.

13. The variable power optical system according to claim 1, wherein The 1st lens group (G1) has at least one negative lens.

14. The variable power optical system according to claim 1, wherein There is an aperture stop (S) at a position closest to the object side of the 3rd lens group (G3), and the 3rd lens group (G3) moves integrally with the aperture stop (S) when power changing.

15. The variable power optical system according to claim 1, wherein The 5th lens group (G5) has at least one positive lens.

16. The variable power optical system according to claim 1, wherein The 2nd lens group (G2) is fixed with respect to the image plane when power changing from the wide angle end to the telephoto end.

17. The variable power optical system according to claim 1, wherein The lens group disposed closest to the image side, i.e., the final lens group (GL), is fixed with respect to the image plane when power changing from the wide angle end to the telephoto end.

18. The variable power optical system according to claim 1, wherein The 3rd lens group (G3) has a positive power vibration isolation lens group that can move in a direction substantially perpendicular to the optical axis.

19. An image pickup device configured to mount the variable power optical system according to any one of claims 1 to 18.

Images