Zoom lenses, imaging optical devices and digital equipment

Abstract

To provide a zoom lens which features a small F-number and good aberration correction over an entire zoom range.SOLUTION: A zoom lens ZL consists of, in order from an 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fourth lens group G4 has at least one positive lens that satisfies a conditional expression: νdp≥65. The zoom lens ZL satisfies the following conditional expressions: 1.19≤f3 / ft≤4.15 and 0.51≤f4 / ft≤1.50.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a zoom lens, an imaging optical device, and a digital device. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2014-106243 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2016-109720 (Patent Document 2) disclose zoom lenses consisting of, in order from the object side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, a fourth lens group having negative power, and a fifth lens group having positive power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-106243 A [Patent Document 2] JP 2016-109720 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a strong demand for zoom lenses to have not only high resolution but also brightness comparable to that of a single focal length. Patent Documents 1 and 2 disclose zoom lenses having an F-number of about 2.8. However, the zoom lenses in Patent Documents 1 and 2 are composed of five lens groups. Therefore, the smaller the F-number of the zoom lens, the greater the fluctuations in spherical aberration and coma aberration caused by magnification change, making it difficult to satisfactorily correct aberrations over the entire zoom range.

[0005] The present disclosure has been made in consideration of these problems, and its purpose is to provide a zoom lens that has a smaller F-number over the entire zoom range and in which aberrations are well corrected, as well as an imaging optical device and a digital device that are equipped with this zoom lens. [Means for solving the problem]

[0006] A zoom lens according to a first aspect of the present disclosure includes, in order from the object side to the image surface side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, a fourth lens group having positive power, a fifth lens group having negative power, and a sixth lens group having positive power. During magnification change, the distance between two adjacent lens groups among the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group changes. The fourth lens group has at least one positive lens that satisfies the following conditional formula (1). The zoom lens according to the first aspect of the present disclosure satisfies the following conditional formulas (2) and (3). νdp≧65 … (1) 1.19≦f3 / ft≦4.15 …(2) 0.51≦f4 / ft≦1.50 …(3) however, νdp: Abbe number for the d-line of at least one positive lens in the fourth lens group, ft: focal length of the entire system at the telephoto end, f3: focal length of the third lens group, f4: focal length of the fourth lens group, It is.

[0007] In a zoom lens according to a second aspect of the present disclosure, in the zoom lens according to the first aspect of the present disclosure, the second lens group has at least one cemented lens that satisfies the following conditional expression (4). nd2p-nd2n≧0.1 … (4) however, nd2p: the refractive index at the d-line of a positive lens constituting at least one cemented lens in the second lens group, nd2n: the refractive index at the d-line of the negative lens constituting at least one cemented lens in the second lens group, It is.

[0008] In a zoom lens according to a third aspect of the present disclosure, in the zoom lens according to the first or second aspect of the present disclosure, the following conditional expression (5) is satisfied. 0.1≦f4 / f1≦0.4 …(5) however, f1: focal length of the first lens group, It is.

[0009] In a zoom lens according to a fourth aspect of the present disclosure, in the zoom lens according to any one of the first to third aspects of the present disclosure, the fifth lens group moves on the optical axis during focusing from a long-distance object to a short-distance object, and the following conditional expression (6) is satisfied. -3.5≦f5 / f6≦-0.5 …(6) however, f5: focal length of the fifth lens group, f6: focal length of the sixth lens group, It is.

[0010] In a zoom lens according to a fifth aspect of the present disclosure, in any of the zoom lenses according to the first to fourth aspects of the present disclosure, the following conditional expression (7) is satisfied. 1.5≦f1 / ft≦10 …(7) however, f1: focal length of the first lens group, It is.

[0011] In a zoom lens according to a sixth aspect of the present disclosure, in the zoom lens according to any one of the first to sixth aspects of the present disclosure, the first lens group is composed of a single positive lens.

[0012] The imaging optical device of the present disclosure includes a zoom lens according to any one of the first to sixth aspects of the present disclosure, and an imaging element that converts an optical image formed on a light receiving surface into an electrical signal. The zoom lens is provided so that an optical image of a subject is formed on the light receiving surface of the imaging element.

[0013] A digital device according to the present disclosure includes the imaging optical device according to the present disclosure, and has at least one of a function of taking still images of a subject and a function of taking videos of the subject. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a zoom lens having a small F-number over the entire zoom range and in which aberrations are well corrected, as well as an imaging optical device and a digital device that include the zoom lens. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of a zoom lens according to a first embodiment. [Diagram 2] FIG. 11 is a diagram showing a configuration of a zoom lens according to a second embodiment. [Diagram 3] FIG. 13 is a diagram showing a configuration of a zoom lens according to a third embodiment. [Figure 4] FIG. 13 is a diagram showing a configuration of a zoom lens according to a fourth embodiment. [Diagram 5] FIG. 13 is a diagram showing a configuration of a zoom lens according to a fifth embodiment. [Figure 6] FIG. 13 is a diagram showing a configuration of a zoom lens according to a sixth embodiment. [Figure 7A] FIG. 2 is a longitudinal aberration diagram at the wide-angle end of Example 1, showing aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 7B] FIG. 2 is a longitudinal aberration diagram in the intermediate focal length state of Example 1, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 7C] FIG. 2 is a longitudinal aberration diagram at the telephoto end of Example 1, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 8A] FIG. 11 is a longitudinal aberration diagram at the wide-angle end of Example 2, showing aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 8B] FIG. 11 is a longitudinal aberration diagram in the intermediate focal length state of Example 2, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 8C] FIG. 11 is a longitudinal aberration diagram at the telephoto end of Example 2, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 9A] FIG. 11 is a diagram showing longitudinal aberration at the wide-angle end of Example 3, illustrating aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 9B] FIG. 13 is a longitudinal aberration diagram in the intermediate focal length state of Example 3, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 9C] FIG. 13 is a longitudinal aberration diagram at the telephoto end of Example 3, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 10A] FIG. 13 is a longitudinal aberration diagram at the wide-angle end of Example 4, showing aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 10B] FIG. 13 is a longitudinal aberration diagram in the intermediate focal length state of Example 4, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 10C] FIG. 13 is a longitudinal aberration diagram at the telephoto end of Example 4, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 11A] FIG. 13 is a longitudinal aberration diagram at the wide-angle end of Example 5, showing aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 11B] FIG. 13 is a longitudinal aberration diagram in the intermediate focal length state of Example 5, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 11C] FIG. 13 is a longitudinal aberration diagram at the telephoto end of Example 5, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 12A] FIG. 13 is a longitudinal aberration diagram at the wide-angle end of Example 6, showing aberrations (spherical aberration, astigmatism, and distortion) at the wide-angle end. [Figure 12B] FIG. 13 is a longitudinal aberration diagram in the intermediate focal length state of Example 6, showing aberrations (spherical aberration, astigmatism, and distortion) in the intermediate focal length state. [Figure 12C] FIG. 13 is a longitudinal aberration diagram at the telephoto end of Example 6, showing aberrations (spherical aberration, astigmatism, and distortion) at the telephoto end. [Figure 13] 1 is a schematic diagram illustrating the configuration of an imaging optical device and a digital device that include a zoom lens according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of the present disclosure will be described below with reference to the drawings. A zoom lens according to the embodiment includes, in order from the object side to the image surface side, a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, a fourth lens group having positive power, a fifth lens group having negative power, and a sixth lens group having positive power. During magnification change, the interval between two adjacent lens groups among the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group changes. The fourth lens group has at least one positive lens that satisfies the following conditional expression (1). The zoom lens according to the present embodiment satisfies the following conditional expressions (2) and (3). νdp≧65 … (1) 1.19≦f3 / ft≦4.15 …(2) 0.51≦f4 / ft≦1.50 …(3) however, νdp: Abbe number for the d-line of at least one positive lens in the fourth lens group, ft: focal length of the entire system at the telephoto end, f3: focal length of the third lens group, f4: focal length of the fourth lens group, It is.

[0017] In a zoom lens including a telephoto range, it is important to correct spherical aberration and axial chromatic aberration during zooming. The zoom lens is composed of six lens groups whose power arrangement is positive, negative, positive, positive, negative, positive in order from the object side. Therefore, the zoom lens can realize a smaller F-number than a zoom lens composed of five lens groups, and can suppress aberration fluctuations caused by zooming.

[0018] By disposing at least one positive lens that satisfies conditional expression (1) in the fourth lens group, it is possible to effectively correct longitudinal chromatic aberration over the entire zoom range.

[0019] Conditional formula (2) is a conditional formula for appropriately setting the focal length of the third lens group and for satisfactorily correcting spherical aberration throughout the entire zoom range. If the value of f3 / ft is below the lower limit of conditional formula (2), the power of the third lens group becomes too strong, so that the fluctuation of spherical aberration becomes large when the third lens group moves during zooming, making it difficult to satisfactorily correct spherical aberration throughout the entire zoom range. If the value of f3 / ft is above the upper limit of conditional formula (2), the power of the third lens group becomes too weak, making it difficult to correct spherical aberration that occurs when the second and fourth lens groups move during zooming.

[0020] Conditional formula (3) is a conditional formula for appropriately setting the focal length of the fourth lens group and for satisfactorily correcting axial chromatic aberration over the entire zoom range. If the value of f4 / ft is below the lower limit of conditional formula (3), the power of the fourth lens group becomes too strong, and the fluctuation of axial chromatic aberration when the fourth lens group moves during zooming becomes large, making it difficult to satisfactorily correct axial chromatic aberration over the entire zoom range. If the value of f4 / ft is above the upper limit of conditional formula (3), the power of the fourth lens group having a positive lens that satisfies conditional formula (1) becomes weak. Therefore, when attempting to obtain a predetermined zoom ratio, axial chromatic aberration occurs in the other lens groups, making it difficult to satisfactorily correct axial chromatic aberration over the entire zoom range.

[0021] In this embodiment, it is preferable that νdp satisfies the following conditional expression (1a). νdp≧70 …(1a)

[0022] Conditional formula (1a) defines a more preferable range within the range defined by conditional formula (1). Therefore, when the value of νdp satisfies conditional formula (1a), the above-mentioned effect can be further increased.

[0023] In this embodiment, it is preferable that f3 / ft satisfy the following conditional expression (2a): 1.5≦f3 / ft≦3.5 …(2a)

[0024] Conditional formula (2a) prescribes a more preferable range within the range prescribe by conditional formula (2). Therefore, when the value of f3 / ft satisfies conditional formula (2a), the above-mentioned effect can be further increased.

[0025] In this embodiment, it is preferable that f4 / ft satisfy the following conditional expression (3a): 0.54≦f4 / ft≦1.10 …(3a)

[0026] Conditional formula (3a) prescribes a more preferable range within the range prescribe by conditional formula (3). Therefore, when the value of f4 / ft satisfies conditional formula (3a), the above-mentioned effect can be further increased.

[0027] In the present embodiment, it is preferable that the second lens group has at least one cemented lens which satisfies the following conditional expression (4). nd2p-nd2n≧0.1 … (4) however, nd2p: the refractive index at the d-line of a positive lens constituting at least one cemented lens in the second lens group, nd2n: the refractive index at the d-line of the negative lens constituting at least one cemented lens in the second lens group, It is.

[0028] Conditional formula (4) specifies the condition for correcting coma aberration at the wide-angle end and spherical aberration at the telephoto end by disposing at least one cemented lens with a large refractive index difference at the cemented surface in the second lens group. If the value of (nd2p-nd2n) is below the lower limit of conditional formula (4), the difference between nd2p and nd2n becomes small, and therefore, at least one of coma aberration at the wide-angle end and spherical aberration at the telephoto end may be insufficiently corrected.

[0029] In this embodiment, it is preferable that the value of (nd2p-nd2n) satisfies the following conditional expression (4a). nd2p-nd2n≧0.15 …(4a)

[0030] Conditional formula (4a) defines a more preferable range within the range defined by conditional formula (4). Therefore, when the value of (nd2p-nd2n) satisfies conditional formula (4a), the above-mentioned effect can be further increased.

[0031] In this embodiment, it is preferable to satisfy the following conditional expression (5). 0.1≦f4 / f1≦0.4 …(5) however, f1: focal length of the first lens group, It is.

[0032] Conditional formula (5) is a conditional formula for appropriately setting the focal length of the fourth lens group and the focal length of the first lens group to achieve a compact overall imaging system and good aberration correction. If the value of f4 / f1 is below the lower limit of conditional formula (5), the power of the first lens group relative to the fourth lens group becomes too weak, making it difficult to shorten the overall optical length and making the overall imaging system large. If the value of f4 / f1 is above the upper limit of conditional formula (5), the power of the first lens group relative to the fourth lens group becomes too strong, making it difficult to correct spherical aberration and axial chromatic aberration at the telephoto end.

[0033] In this embodiment, it is preferable that f4 / f1 satisfies the following conditional expression (5a). 0.15≦f4 / f1≦0.35 …(5a)

[0034] Conditional formula (5a) prescribes a more preferable range within the range prescribe by conditional formula (5). Therefore, when the value of f4 / f1 satisfies conditional formula (5a), the above-mentioned effect can be further increased.

[0035] In the present embodiment, during focusing from a long-distance object to a short-distance object, it is preferable that the fifth lens group moves on the optical axis and that the following conditional expression (6) is satisfied. -3.5≦f5 / f6≦-0.5 …(6) however, f5: focal length of the fifth lens group, f6: focal length of the sixth lens group, It is.

[0036] Conditional formula (6) is a conditional formula for appropriately setting the ratio of the focal length of the fifth lens group to the focal length of the sixth lens group, thereby suppressing aberration fluctuations due to focusing. The sixth lens group, which has positive power, corrects aberrations that occur when the fifth lens group, which has negative power, moves. If the value of f5 / f6 is below the lower limit of conditional formula (6), the power of the fifth lens group relative to the power of the sixth lens group becomes too weak, so that the sixth lens group overcorrects aberrations against fluctuations such as curvature of field that occur in the fifth lens group during focusing. If the value of f5 / f6 is above the upper limit of conditional formula (6), the power of the fifth lens group relative to the sixth lens group becomes too strong, so that the sixth lens group overcorrects aberrations against fluctuations such as curvature of field that occur in the fifth lens group during focusing.

[0037] In this embodiment, it is preferable that f5 / f6 satisfy the following conditional expression (6a). -1.2 ≤ f5 / f6 ≤ -0.4 … (6a)

[0038] Conditional formula (6a) prescribes a more preferable range within the range prescribed by conditional formula (6). Therefore, when the value of f5 / f6 satisfies conditional formula (6a), the above-mentioned effect can be further increased.

[0039] In this embodiment, it is preferable to satisfy the following conditional expression (7). 1.5≦f1 / ft≦10 …(7) however, f1: focal length of the first lens group, It is.

[0040] Conditional formula (7) is a conditional formula for appropriately setting the focal length of the first lens group to achieve a compact overall imaging system and good aberration correction. If the value of f1 / ft is below the lower limit of conditional formula (7), the power of the first lens group becomes too strong, making it difficult to correct spherical aberration and axial chromatic aberration at the telephoto end. If the value of f1 / ft is above the upper limit of conditional formula (7), the power of the first lens group becomes too weak, making it difficult to shorten the overall optical length and resulting in a large overall imaging system.

[0041] In this embodiment, it is preferable that f1 / ft satisfy the following conditional expression (7a): 1.7≦f1 / ft≦5 …(7a)

[0042] Conditional formula (7a) prescribes a more preferable range within the range prescribed by conditional formula (7). Therefore, when the value of f1 / ft satisfies conditional formula (7a), the above-mentioned effect can be further increased.

[0043] In this embodiment, it is preferable that the first lens group is composed of a single positive lens.

[0044] The first lens group of a zoom lens that has a wide angle of view at the wide-angle end (for example, an angle of view at the wide-angle end exceeding 80°) tends to have a very large lens diameter. By configuring the first lens group from a single positive lens, it is possible to reduce the weight of the entire zoom lens.

[0045] <Specific Optical Configuration of the Zoom Lens According to the Embodiment> Figures 1 to 6 are lens configuration diagrams showing the configuration of a zoom lens ZL according to first to sixth embodiments, respectively. In each of Figures 1 to 6, "Wide" is a lens cross-sectional view at the wide-angle end, "Middle" is a lens cross-sectional view at a middle focal length state, "Tele" is a lens cross-sectional view at the telephoto end, and "AX" refers to the optical axis. "Wide", "Middle", and "Tele" are all lens cross-sectional views when focusing on an object at infinity.

[0046] (First embodiment) As shown in Fig. 1, the zoom lens ZL according to the first embodiment is composed of, in order from the object side to the image surface side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. During magnification change, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, during magnification change, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. During magnification change, the aperture stop ST moves together with the fourth lens group G4. When focusing from a long-distance object to a short-distance object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0047] When each lens of the first lens group G1 to the sixth lens group G6 in the first embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0048] The first lens group G1 is composed of a biconvex positive lens L1a.

[0049] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0050] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a positive meniscus lens L3b with a convex surface facing the object side. The negative meniscus lens L3a and the positive meniscus lens L3b are cemented together to form a cemented lens CL3.

[0051] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0052] The fifth lens group G5 is composed of a negative meniscus lens L5a having a convex surface facing the object side. The negative meniscus lens L5a is an aspheric single lens.

[0053] The sixth lens group G6 is composed of a biconvex positive lens L6a, a biconcave negative lens L6b, and a positive meniscus lens L6c with a convex surface facing the object side. The positive lens L6a, the negative lens L6b, and the positive meniscus lens L6c are cemented together to form a cemented lens CL6.

[0054] (Second embodiment) As shown in FIG. 2, the zoom lens ZL according to the second embodiment is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. When changing the magnification, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, when changing the magnification, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. When changing the magnification, the aperture stop ST moves integrally with the fourth lens group G4. When focusing from a long-distance object to a short-distance object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0055] When each lens of the first lens group G1 to the sixth lens group G6 in the second embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0056] The first lens group G1 is composed of a biconvex positive lens L1a.

[0057] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0058] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a positive meniscus lens L3b with a convex surface facing the object side. The negative meniscus lens L3a and the positive meniscus lens L3b are cemented together to form a cemented lens CL3.

[0059] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0060] The fifth lens group G5 is composed of a positive meniscus lens L5a with a convex surface facing the image surface IM, and a biconcave negative lens L5b. The positive meniscus lens L5a and the negative lens L5b are cemented together to form a cemented lens CL5.

[0061] The sixth lens group G6 is composed of a biconvex positive lens L6a and a negative meniscus lens L6b with a convex surface facing the image plane IM. The negative meniscus lens L6b is an aspheric single lens.

[0062] (Third embodiment) As shown in FIG. 3, the zoom lens ZL according to the third embodiment is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. When changing the magnification, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, when changing the magnification, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. When changing the magnification, the aperture stop ST moves integrally with the fourth lens group G4. When focusing from a long-distance object to a short-distance object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0063] When each lens of the first lens group G1 to the sixth lens group G6 in the third embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0064] The first lens group G1 is composed of a biconvex positive lens L1a.

[0065] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0066] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a positive meniscus lens L3b with a convex surface facing the object side. The negative meniscus lens L3a and the positive meniscus lens L3b are cemented together to form a cemented lens CL3.

[0067] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0068] The fifth lens group G5 is composed of a biconvex positive lens L5a and a biconcave negative lens L5b, which are cemented together to form a cemented lens CL5.

[0069] The sixth lens group G6 is composed of a biconvex positive lens L6a and a biconcave negative lens L6b.

[0070] (Fourth embodiment) As shown in FIG. 4, the zoom lens ZL according to the fourth embodiment is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. When changing the magnification, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, when changing the magnification, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. When changing the magnification, the aperture stop ST moves integrally with the fourth lens group G4. When focusing from a distant object to a close object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0071] When each lens of the first lens group G1 to the sixth lens group G6 in the fourth embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0072] The first lens group G1 is composed of a biconvex positive lens L1a.

[0073] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0074] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a positive meniscus lens L3b with a convex surface facing the object side. The negative meniscus lens L3a and the positive meniscus lens L3b are cemented together to form a cemented lens CL3.

[0075] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0076] The fifth lens group G5 is composed of a negative meniscus lens L5a having a convex surface facing the object side. The negative meniscus lens L5a is an aspheric single lens.

[0077] The sixth lens group G6 is composed of a biconvex positive lens L6a, a biconcave negative lens L6b, and a positive meniscus lens L6c with a convex surface facing the object side. The negative lens L6b and the positive meniscus lens L6c are cemented together to form a cemented lens CL6.

[0078] (Fifth embodiment) As shown in FIG. 5, the zoom lens ZL according to the fifth embodiment is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. When changing the magnification, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, when changing the magnification, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. When changing the magnification, the aperture stop ST moves integrally with the fourth lens group G4. When focusing from a long-distance object to a short-distance object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0079] When each lens of the first lens group G1 to the sixth lens group G6 in the fifth embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0080] The first lens group G1 is composed of a biconvex positive lens L1a.

[0081] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0082] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a positive meniscus lens L3b with a convex surface facing the object side. The negative meniscus lens L3a and the positive meniscus lens L3b are cemented together to form a cemented lens CL3.

[0083] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0084] The fifth lens group G5 is composed of a negative meniscus lens L5a having a convex surface facing the object side. The negative meniscus lens L5a is an aspheric single lens.

[0085] The sixth lens group G6 is composed of a biconvex positive lens L6a, a biconcave negative lens L6b, and a positive meniscus lens L6c with a convex surface facing the object side. The negative lens L6b and the positive meniscus lens L6c are cemented together to form a cemented lens CL6.

[0086] (Sixth embodiment) As shown in FIG. 6, the zoom lens ZL according to the sixth embodiment is composed of, in order from the object side, a first lens group G1 having positive power, a second lens group G2 having negative power, a third lens group G3 having positive power, a fourth lens group G4 having positive power, a fifth lens group G5 having negative power, and a sixth lens group G6 having positive power. When changing the magnification, the interval between two adjacent lens groups among the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 changes. For example, when changing the magnification, the sixth lens group G6 is fixed, and the first to fifth lens groups G1, G2, G3, G4, and G5 move. When changing the magnification, the aperture stop ST moves integrally with the fourth lens group G4. When focusing from a distant object to a close object, the fifth lens group G5 is moved toward the image surface IM along the optical axis AX.

[0087] When each lens of the first lens group G1 to the sixth lens group G6 in the sixth embodiment is viewed in terms of a paraxial surface shape, the lenses are configured as follows, in order from the object side:

[0088] The first lens group G1 is composed of a biconvex positive lens L1a.

[0089] The second lens group G2 is composed of a negative meniscus lens L2a with a convex surface facing the object side, a biconcave negative lens L2b, and a positive meniscus lens L2c with a convex surface facing the object side. The negative lens L2b and the positive meniscus lens L2c are cemented together to form a cemented lens CL2.

[0090] The third lens group G3 is composed of a negative meniscus lens L3a with a convex surface facing the object side, and a biconvex positive lens L3b. The negative meniscus lens L3a and the positive lens L3b are cemented together to form a cemented lens CL3.

[0091] The fourth lens group G4 is composed of a biconvex positive lens L4a, a biconcave negative lens L4b, a biconvex positive lens L4c, a biconvex positive lens L4d, a negative meniscus lens L4e with a convex surface facing the object side, and a biconvex positive lens L4f. The positive lens L4a is an aspheric single lens. The negative lens L4b and the positive lens L4c are cemented together to form a cemented lens CL4a. The negative meniscus lens L4e and the positive lens L4f are cemented together to form a cemented lens CL4b. An aperture stop ST is disposed between the positive lens L4a and the negative lens L4b.

[0092] The fifth lens group G5 is composed of a biconvex positive lens L5a and a biconcave negative lens L5b, which are cemented together to form a cemented lens CL5.

[0093] The sixth lens group G6 is composed of a biconvex positive lens L6a and a biconcave negative lens L6b. EXAMPLES

[0094] The configurations of the zoom lenses according to the embodiments will be described in more detail below with reference to the construction data of the examples. Examples 1 to 6 given here are numerical examples corresponding to the above-mentioned first to sixth embodiments, respectively, and the lens configuration diagrams (FIGS. 1 to 6) of the first to sixth embodiments show the optical configurations (lens arrangement, lens shape, etc.) of the corresponding Examples 1 to 6, respectively.

[0095] In the construction data for each embodiment, the surface data, starting from the left column, are: surface number (object: object surface, stop: aperture stop ST, image: image surface IM), radius of curvature r (mm), axial surface spacing d (mm), refractive index nd for d-line (wavelength 587.56 nm), and Abbe number vd for d-line. Surfaces with an * next to surface number i are aspheric, and the surface shape is defined by the following equation (AS) using a local Cartesian coordinate system (x, y, z) with the surface vertex as the origin. Aspheric data includes aspheric coefficients, etc. Note that the coefficients of terms not listed in the aspheric data for each embodiment are 0, and for all data, en = × 10 -n It is. z = (c h 2 ) / [1+√{1-(1+K)·c 2 h 2}]+Σ(Aj·hj) …(AS) however, h: Height perpendicular to the z-axis (optical axis AX) 2 =x 2 +y 2 ), z: Sag amount in the direction of the optical axis AX at height h (based on the vertex of the surface), c: Curvature at the vertex of the face (the inverse of the radius of curvature r), K: conic constant, Aj: jth aspheric coefficient, It is.

[0096] As various data, the zoom ratio and the focal length of the entire system (Fl, mm), F-number (Fno.), half angle of view (ω, °), image height (y'max, mm), lens total length (TL, mm), back focus (BF, mm), and variable axial surface spacing (variable: di (i: surface number), mm) are shown for each focal length state: wide-angle end (Wide), middle focal length state (Middle), and telephoto end (Tele). In addition, as lens group data, the focal length (mm) of each lens group is shown. However, the back focus BF is the distance from the last lens surface to the paraxial image surface expressed as the air equivalent length. The lens total length TL is the distance from the front lens surface to the last lens surface plus the back focus BF.

[0097] 7A to 12C show the amount of spherical aberration for the d-line (wavelength 587.56 nm) (shown by a solid line), the amount of spherical aberration for the C-line (wavelength 656.28 nm) (shown by a dashed-dotted line), and the amount of spherical aberration for the g-line (wavelength 435.84 nm) (shown by a dashed line), each expressed as the deviation (unit: mm) of the focal position in the direction of the optical axis AX from the paraxial image plane. The vertical axis shows the value obtained by normalizing the incidence height to the pupil by its maximum height (i.e., the relative pupil height).

[0098] In the astigmatism diagrams of Figures 7A to 12C, the dashed line T represents the tangential image plane for the d-line, as a deviation (unit: mm) of the focal position in the direction of the optical axis AX from the paraxial image plane, and the solid line S represents the sagittal image plane for the d-line, as a deviation (unit: mm) of the focal position in the direction of the optical axis AX from the paraxial image plane. The vertical axis represents the image height (IMG HT, unit: mm).

[0099] 7A to 12C, the horizontal axis represents the ratio (unit: %) of the actual image height to the ideal image height for the distortion for the d-line, and the vertical axis represents the image height (IMG HT, unit: mm). Note that the maximum value of the image height IMG HT (i.e., the maximum image height y'max) corresponds to half the diagonal length of the light receiving surface SS of the image sensor SR (i.e., the diagonal image height).

[0100] Numerical Example 1 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 115.171 8.748 1.62041 60.34 2 -956.660 variable 3 882.848 2.232 1.66672 48.32 4 33.137 8.621 5 -141.452 1.983 1.69895 30.05 6 36.415 6.011 2.00100 29.13 7 136.441 variable 8 191.669 1.851 1.48749 70.44 9 46.727 4.834 1.84666 23.78 10 222.331 variable 11* 104.983 4.457 1.58313 59.46 12* -206.547 3.513 13 (stop) infinity 6.172 14 -56.422 1.969 1.69895 30.05 15 149.044 8.299 1.49700 81.61 16 -59.584 0.197 17 134.537 9.381 1.59282 68.62 18 -57.519 0.197 19 53.262 2.101 1.80100 34.97 20 25.671 12.729 1.59282 68.62 21 -165.367 variable 22* 137.459 1.707 1.69350 53.20 23* 24.234 variable 24 58.504 7.700 2.00100 29.13 25 -44.490 1.602 1.69895 30.05 26 25.485 5.719 1.76200 40.10 27 72.462 23.376 image infinity Aspheric Data Surface number K A4 A6 A8 A10 11 0 -2.0939e-006 -4.0798e-009 -1.5073e-011 -6.8663e-015 12 0 2.9141e-006 -2.8724e-009 -1.6453e-011 0 22 0 -4.4947e-006 1.5426e-008 -5.9265e-011 9.9749e-014 23 0 -6.5436e-006 1.2698e-008 -9.7184e-011 1.4562e-013 Various data Zoom ratio 1.91 Wide Middle Tele Fl 33.612 45.956 64.079 Fno. 2.000 2.000 2.000 ω 22.902 17.171 12.495 y'max 14.200 14.200 14.200 TL 189.833 189.833 189.833 BF 23.376 23.376 23.376 d2 1.818 20.293 34.481 d7 17.900 9.949 3.572 d10 29.229 15.892 1.895 d21 3.282 4.812 6.166 d23 14.205 15.487 20.318 Lens Group Data Group (plane) focal length 1 ( 1- 2) 166.209 2 ( 3- 7) -41.162 3 ( 8- 10) 153.579 4 ( 11- 21) 39.054 5 ( 22- 23) -42.686 6 ( 24- 27) 58.840

[0101] Numerical Example 2 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 123.032 9.372 1.62041 60.34 2 -922.008 variable 3 1397.732 2.363 1.59282 68.62 4 32.317 11.218 5 -158.086 1.983 1.69895 30.05 6 34.441 6.410 2.00100 29.13 7 131.774 variable 8 391.870 1.851 1.48749 70.44 9 50.530 4.912 1.84666 23.78 10 297.321 variable 11* 174.448 4.615 1.58313 59.46 12* -96.145 3.414 13 (stop) infinity 5.196 14 -81.793 1.838 1.69895 30.05 15 66.471 10.111 1.49700 81.61 16 -52.878 0.197 17 285.688 6.044 1.59282 68.62 18 -77.204 0.197 19 85.075 1.969 1.67270 32.17 20 33.037 12.405 1.59282 68.62 21 -68.424 variable 22 -3258.716 4.067 1.84666 23.78 23 -43.747 1.195 1.71736 29.50 24 24.924 variable 25 60.427 6.929 2.00100 29.13 26 -56.938 2.919 27* -38.507 1.969 1.80610 40.73 28* -656.496 19.858 image infinity Aspheric Data Surface number K A4 A6 A8 A10 11 0 -3.4517e-006 6.1976e-012 -4.1754e-013 -6.9770e-016 12 0 2.9317e-006 1.0498e-009 1.3788e-013 0 27 0 -9.6138e-007 3.6470e-008 -8.3787e-011 6.8409e-014 28 0 -6.8467e-006 3.6554e-008 -8.8098e-011 8.8328e-014 Various data Zoom ratio 1.91 Wide Middle Tele Fl 33.616 45.952 64.078 Fno. 2.000 2.000 2.000 ω 22.900 17.172 12.495 y'max 14.200 14.200 14.200 TL 189.825 189.825 189.825 BF 19.858 19.858 19.858 d2 1.843 21.484 36.815 d7 25.904 14.335 4.011 d10 22.373 12.132 2.187 d21 3.279 4.613 5.808 d24 15.392 16.227 19.970 Lens Group Data Group (plane) focal length 1 ( 1- 2) 175.564 2 ( 3- 7) -45.296 3 ( 8- 10) 179.819 4 ( 11- 21) 37.187 5 ( 22- 24) -38.392 6 ( 25- 28) 60.801

[0102] Numerical Example 3 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 101.807 9.145 1.58913 61.25 2 -1261.681 variable 3 955.511 2.101 1.80610 40.73 4 35.732 9.244 5 -286.128 1.851 1.68893 31.16 6 34.704 5.507 2.00100 29.13 7 99.749 variable 8 317.133 1.720 1.48749 70.44 9 47.002 5.021 1.84666 23.78 10 455.880 variable 11* 244.645 4.611 1.58313 59.46 12* -83.754 3.151 13 (stop) infinity 6.952 14 -44.906 1.969 1.64769 33.84 15 124.483 8.780 1.49700 81.61 16 -49.727 0.197 17 256.443 8.112 1.59282 68.62 18 -52.284 0.197 19 88.222 1.969 1.71736 29.50 20 30.942 11.872 1.59282 68.62 21 -107.803 variable 22 519.548 2.733 1.84666 23.78 23 -131.294 1.195 1.58144 40.89 24 25.935 variable 25 44.571 6.956 1.80610 40.73 26 -51.731 2.065 27 -48.333 1.444 1.65844 50.85 28 71.489 22.900 image infinity Aspheric Data Surface number K A4 A6 A8 A10 11 0 -3.5961e-006 2.9811e-009 -1.4360e-012 -8.3685e-016 12 0 2.2997e-006 4.6753e-009 0 0 Various data Zoom ratio 1.91 Wide Middle Tele Fl 33.613 45.949 64.071 Fno. 2.000 2.000 2.000 ω 22.902 17.173 12.496 y'max 14.200 14.200 14.200 TL 189.302 189.302 189.302 BF 22.900 22.900 22.900 d2 1.926 21.352 36.146 d7 16.470 9.584 4.224 d10 30.782 16.672 2.199 d21 3.544 5.306 6.393 d24 16.886 16.694 20.648 Lens Group Data Group (plane) focal length 1 ( 1- 2) 160.304 2 ( 3- 7) -38.116 3 ( 8- 10) 135.912 4 ( 11- 21) 40.728 5 ( 22- 24) -53.596 6 ( 25- 28) 76.669

[0103] Numerical Example 4 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 107.991 8.619 1.62041 60.34 2 -1158.126 variable 3 889.021 2.101 1.83400 37.16 4 36.824 7.223 5 -131.793 1.851 1.70154 41.24 6 38.515 5.237 2.00100 29.13 7 129.524 variable 8 96.125 1.851 1.48749 70.44 9 43.805 4.794 1.84666 23.78 10 161.329 variable 11* 91.643 4.894 1.58313 59.46 12* -353.919 3.757 13 (stop) infinity 6.423 14 -52.187 1.969 1.72825 28.32 15 119.326 8.840 1.49700 81.61 16 -56.373 0.197 17 136.023 9.582 1.59282 68.62 18 -57.624 0.197 19 47.308 2.101 1.83400 37.16 20 25.599 13.117 1.59282 68.62 21 -275.086 variable 22* 97.414 1.707 1.69350 53.20 23* 24.661 variable 24 68.746 6.339 1.95375 32.32 25 -62.637 1.503 26 -81.643 1.589 1.67270 32.17 27 25.034 5.318 1.91082 35.25 28 55.154 23.665 image infinity Aspheric surface Surface number K A4 A6 A8 A10 11 0 -2.2417e-006 -5.0207e-009 -1.3180e-011 -1.1676e-014 12 0 2.4469e-006 -3.4189e-009 -1.7640e-011 0 22 0 -4.7516e-006 7.5805e-009 -3.3917e-011 5.2583e-014 23 0 -5.9451e-006 5.7516e-010 -4.1954e-011 8.3172e-015 Various data Zoom ratio 1.91 Wide Middle Tele Fl 33.610 45.951 64.071 Fno. 2.000 2.000 2.000 ω 22.904 17.172 12.496 y'max 14.200 14.200 14.200 TL 189.825 189.825 189.825 BF 23.665 23.665 23.665 d2 4.889 22.111 34.590 d7 17.077 9.097 2.873 d10 26.204 14.470 1.961 d21 3.282 5.852 8.456 d23 15.499 15.422 19.071 Lens Group Data Group (plane) focal length 1 ( 1- 2) 159.633 2 ( 3- 7) -35.514 3 ( 8- 10) 122.187 4 ( 11- 21) 40.678 5 ( 22- 23) -48.076 6 ( 24- 28) 62.502

[0104] Numerical Example 5 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 95.747 9.093 1.62041 60.34 2 -4231.234 variable 3 389.905 2.101 1.83400 37.16 4 36.958 9.285 5 -137.547 1.851 1.80610 40.73 6 38.210 5.269 2.00100 29.13 7 130.771 variable 8 94.430 1.851 1.48749 70.44 9 44.748 4.691 1.84666 23.78 10 165.891 variable 11* 80.459 4.627 1.58313 59.46 12* -528.861 3.907 13 (stop) infinity 6.373 14 -53.306 1.969 1.72825 28.32 15 164.124 8.447 1.49700 81.61 16 -55.829 0.197 17 179.277 9.341 1.59282 68.62 18 -55.097 0.197 19 48.859 2.101 1.80100 34.97 20 25.861 13.177 1.59282 68.62 21 -242.253 variable 22* 102.358 1.707 1.69350 53.20 23* 24.648 variable 24 52.182 6.491 1.95375 32.32 25 -70.683 1.647 26 -85.480 1.589 1.68893 31.16 27 28.361 4.253 1.91082 35.25 28 49.868 23.499 image infinity Aspheric surface Surface number K A4 A6 A8 A10 11 0 -1.8732e-006 -5.1904e-009 -2.0546e-011 -2.0037e-014 12 0 3.3028e-006 -2.7258e-009 -2.9138e-011 0 22 0 -1.8064e-006 -5.9294e-010 -1.3208e-011 2.6206e-014 23 0 -2.7807e-006 -6.4726e-009 -1.8245e-011 -2.7772e-014 Various data Zoom ratio 2.07 Wide Middle Tele Fl 30.984 44.639 64.072 Fno. 2.000 2.000 2.000 ω 24.622 17.646 12.496 y'max 14.200 14.200 14.200 TL 189.824 189.824 189.824 BF 23.499 23.499 23.499 d2 4.121 22.578 34.261 d7 15.948 8.302 2.838 d10 29.619 15.507 1.742 d21 3.282 6.117 8.993 d23 13.191 13.657 18.326 Lens Group Data Group (plane) focal length 1 ( 1- 2) 151.035 2 ( 3- 7) -32.410 3 ( 8- 10) 121.406 4 ( 11- 21) 39.939 5 ( 22- 23) -47.240 6 ( 24- 28) 62.525

[0105] Numerical Example 6 Unit: mm Surface Data Surface number rd nd vd object infinity infinity 1 104.086 9.346 1.62041 60.34 2 -1693.448 variable 3 2111.147 2.101 1.74400 44.79 4 35.047 10.022 5 -169.569 1.851 1.68893 31.16 6 35.546 5.457 2.00100 29.13 7 108.511 variable 8 1000.462 1.851 1.48749 70.44 9 53.365 5.146 1.84666 23.78 10 -1791.416 variable 11* 217.282 4.583 1.58313 59.46 12* -89.438 4.054 13 (stop) infinity 5.568 14 -70.150 1.969 1.68893 31.16 15 124.707 7.654 1.49700 81.61 16 -64.074 0.197 17 184.397 7.095 1.59282 68.62 18 -62.571 0.197 19 168.047 1.969 1.68893 31.16 20 32.579 12.419 1.59282 68.62 21 -69.651 variable 22 952.736 3.421 1.84666 23.78 23 -68.791 1.195 1.68893 31.16 24 28.192 variable 25 48.893 6.964 2.00100 29.13 26 -63.709 2.284 27 -54.418 1.576 1.72825 28.32 28 83.512 22.823 image infinity Aspherical data Surface number K A4 A6 A8 A10 11 0 -3.5975e-006 1.6347e-009 -4.1326e-014 -1.8335e-015 12 0 2.3178e-006 3.2314e-009 0 0 Various data Zoom ratio 1.91 Wide Middle Tele Fl 33.614 45.952 64.073 Fno. 2.000 2.000 2.000 ω 22.901 17.172 12.496 y’max 14.200 14.200 14.200 TL 189.827 189.827 189.827 BF 22.823 22.823 22.823 d2 2.112 21.525 36.529 d7 17.522 10.320 4.401 d10 29.200 15.578 1.745 d21 3.543 5.381 6.828 d24 17.708 17.280 20.582 Lens group data Group (surface) Focal length 1 (1 - 2) 158.370 2 (3 - 7) -37.448 3 (8 - 10) 130.267 4 (11 - 21) 41.470 5 (22 - 24) -47.250 6 ( 25- 28) 60.618

[0106] Table 1 shows the values ​​of each embodiment. Table 2 shows the values ​​corresponding to the conditional expressions of each embodiment. [Table 1] [Table 2]

[0107] Fig. 13 is a schematic diagram of an imaging optical device LU and a digital device DU equipped with a zoom lens ZL according to this embodiment. As shown in Fig. 13, the digital device DU is equipped with an imaging optical device LU. The imaging optical device LU is equipped with, in order from the object (i.e., subject) side, a zoom lens ZL (AX indicates the optical axis) that forms an optical image (image surface IM) of the object, and an imaging element SR that converts the optical image formed on a light receiving surface (imaging surface) SS by the zoom lens ZL into an electrical signal. If necessary, a parallel plane plate (e.g., a cover glass of the imaging element SR; equivalent to an optical filter such as an optical low-pass filter or an infrared cut filter that is arranged as necessary) may be arranged in the imaging optical device LU.

[0108] The image sensor SR may be, for example, a solid-state image sensor such as a charge-coupled device (CCD) image sensor having a plurality of pixels or a complementary metal-oxide semiconductor (CMOS) image sensor. The zoom lens ZL is provided so that an optical image of a subject is formed on a light receiving surface SS, which is a photoelectric conversion section of the image sensor SR. The optical image formed by the zoom lens ZL is converted into an electrical signal by the image sensor SR.

[0109] In addition to the imaging optical device LU, the digital device DU is equipped with a signal processing unit 1, a control unit 2, a memory 3, an operation unit 4, and a display unit 5. The signal processing unit 1 performs predetermined digital image processing or image compression processing or other processing as necessary on the signal generated by the imaging element SR to generate a digital video signal. The digital video signal is recorded in the memory 3 (semiconductor memory, optical disk, etc.). The digital video signal may be transmitted to other devices.

[0110] The control unit 2 is made up of a microcomputer, and centrally controls functions such as the shooting function (still image shooting function, video shooting function, etc.) and image playback function, as well as the lens movement mechanism for zooming, focusing, camera shake correction, etc. For example, the control unit 2 controls the imaging optical device LU so that it takes at least one of still images and video of a subject.

[0111] The display unit 5 includes a display such as an LCD monitor, and displays an image using the image signal converted by the image sensor SR or the image information recorded in the memory 3. The operation unit 4 includes operation members such as an operation button (e.g., a release button) and an operation dial (e.g., a shooting mode dial), and transmits information input by the operator to the control unit 2.

[0112] Although the embodiment and the example have been described, the embodiment disclosed herein should be considered as illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0113] 1 signal processing unit, 2 control unit, 3 memory, 4 operation unit, 5 display unit, AX optical axis, CL2, CL3, CL4a, CL4b, CL5, CL6 cemented lenses, DU digital device, G1 first lens group, G2 second lens group, G3 third lens group, G4 fourth lens group, G5 fifth lens group, G6 sixth lens group, IM image surface, L1a, L2a, L2b, L2c, L3a, L3b, L4a, L4b, L4c, L4d, L4e, L4f, L5a, L5b, L6a, L6b, L6c lenses, LU imaging optical device, SR imaging element, SS light receiving surface, ST aperture stop, ZL zoom lens.

Claims

1. In order from the object side to the image plane side, a first lens group having a positive power; a second lens group having negative power; a third lens group having a positive power; and a fourth lens group having positive power; and a fifth lens group having negative power; and a sixth lens group having a positive power, a distance between two adjacent lens groups among the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group changes during magnification variation; The fourth lens group has at least one positive lens that satisfies the following conditional expression (1): The second lens group has at least one cemented lens that satisfies the following conditional expression (5): A zoom lens further satisfying the following conditions (2), (3), and (4): νdp≧65 ... (1) 1.19≦f3 / ft≦4.15 … (2) 0.51≦f4 / ft≦1.50 ... (3) 0.1≦f4 / f1≦0.4 ... (4) nd2p−nd2n≧0.1 (5) however, νdp: Abbe number for the d-line of the at least one positive lens in the fourth lens group, ft: focal length of the entire system at the telephoto end, f1: the focal length of the first lens group, f3: the focal length of the third lens group, f4: the focal length of the fourth lens group, nd2p: the refractive index at the d-line of the positive lens constituting the at least one cemented lens in the second lens group, nd2n: the refractive index at the d-line of the negative lens constituting the at least one cemented lens in the second lens group, It is.

2. When focusing from a distant object to a close object, the fifth lens group moves along the optical axis, The zoom lens according to claim 1 , which satisfies the following conditional expression (6): −3.5≦f5 / f6≦−0.5 … (6) however, f5: the focal length of the fifth lens group, f6: the focal length of the sixth lens group, It is.

3. The zoom lens according to claim 1 or 2, which satisfies the following conditional expression (7): 1.5≦f1 / ft≦10... (7).

4. 4. The zoom lens according to claim 1, wherein the first lens group is composed of a single positive lens.

5. The zoom lens according to any one of claims 1 to 4, an image sensor that converts an optical image formed on the light receiving surface into an electrical signal; an imaging optical device, the zoom lens being provided so that an optical image of a subject is formed on the light receiving surface of the imaging element;

6. The imaging optical device according to claim 5, A digital device having at least one of a function of taking still images of the subject and a function of taking videos of the subject.

Images