Zoom lens and image capturing device

Abstract

To provide a zoom lens that has a large aperture and yet can be reduced in entire size thereof, and is well corrected for various aberrations over an entire zoom range, and to provide an image capturing device having the same.SOLUTION: In order to achieve the above objective, a zoom lens provided herein comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a rear group having at least one lens group. When zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side. An aperture stop is provided on the object side of the third lens group. The zoom lens satisfies predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens and an imaging device, and more particularly to a zoom lens suitable for imaging devices using solid-state imaging elements (CCD, CMOS, etc.) such as digital still cameras and digital video cameras, and an imaging device equipped with the zoom lens. [Background technology]

[0002] Imaging devices using solid-state imaging elements, such as digital still cameras and digital video cameras, are widely used. Interchangeable-lens imaging devices, such as single-lens reflex cameras and mirrorless cameras, allow users to capture images with various angles of view, brightness, depth of field, and other characteristics by simply changing lenses. In recent years, there has been a demand for interchangeable lenses with larger aperture ratios to enable capturing images with greater brightness and blur. Conventional zoom lenses often have an F-number of around 2.8, even at their fastest. Those seeking a lens faster than this often have no choice but to choose a prime lens. However, because prime lenses have a fixed focal length, they have drawbacks, such as a limited capture range, the hassle of changing lenses to change to a different focal length, and the need to carry multiple lenses with different focal lengths. To address these issues and improve convenience, a large-aperture zoom lens is desirable.

[0003] Furthermore, with the increasing popularity of compact mirrorless single-lens cameras that do not have mirrors or optical viewfinders, there is a demand for compact cameras as well as compact lenses. However, when attempting to realize a zoom lens with a large aperture ratio, the lens diameter and aperture diameter become large, and the overall length of the zoom lens also becomes long. Furthermore, the drive mechanism and other components also become large, which results in a problem of the overall size of the lens unit, including the lens barrel.

[0004] To achieve a compact zoom lens, it is necessary to reduce the aperture diameter, the diameter of the lens closest to the object, and the diameter of the lens closest to the image, as well as the overall length of the zoom lens. In addition, to achieve a compact overall lens unit, including the lens barrel, it is desirable to embed the focus drive mechanism, aperture unit, and various mechanical components in a location within the overall lens unit, including the lens barrel, where the optical system diameter is small. Therefore, it is necessary to provide an area in which lenses with small outer diameters are located. Furthermore, if the focus group is heavy, a drive mechanism with a large drive force is required, making it difficult to achieve a compact overall lens unit, including the lens barrel. Therefore, it is also necessary to reduce the size of the focus group.

[0005] Known examples of zoom lenses with a large aperture ratio and an F-number of about 2.0 include Patent Documents 1, 2, and 3. Patent Document 1 proposes a zoom lens that is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group having positive refractive power, and that has a focal length of about 25 mm at the wide-angle end and a focal length of about 50 mm at the telephoto end when converted into a 35 mm format, and an F-number of about 2.0. Patent Document 2 proposes a zoom lens that is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, and that has a focal length of about 28 mm at the wide-angle end, a focal length of about 66 mm at the telephoto end, and an F-number of about 2.0. Patent Document 3 proposes a zoom lens that is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, and that has a focal length of about 28 mm at the wide-angle end, a focal length of about 70 mm at the telephoto end, and an F-number of about 2.0. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2020-190680 [Patent Document 2] Patent Publication No. 2016-014841 [Patent Document 3] Patent Publication No. 2019-015956 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the zoom lens of Patent Document 1, the first lens group is composed of only one convex lens, and the refractive power of that lens is weak, so the overall size of the zoom lens at the wide-angle end is insufficient. Furthermore, the combined F-number of the first to fourth lens groups is large, which leads to an increase in the size of the lens system from the first to fourth lens groups. Furthermore, while an example using an APS-sized image sensor has been proposed, the overall size and weight of the zoom lens is not sufficiently reduced relative to the size of the image sensor, resulting in a problem of the overall size of the zoom lens.

[0008] Furthermore, in the zoom lens of Patent Document 2, the refractive power of the combined lens group from the first lens group to the third lens group is not optimized, so the diameter of the light beam incident on the fourth lens group, which is the focus group, is large in the radial direction, making it impossible to reduce the size of the focus group. Furthermore, because the focus group is located at the location in the lens system from the aperture to the image plane where the diameter of the light beam is largest, the outer diameter of the zoom lens is large. Furthermore, because the distance from the image-side lens surface of the lens located closest to the image plane (back focus) is long, there is a problem that the zoom lens is not optimized for mirrorless cameras with short back focus, and there is also a problem that the overall length of the zoom lens is long and large.

[0009] Furthermore, the zoom lens of Patent Document 3 employs a four-group lens configuration, which places limitations on the arrangement of refractive powers of each lens group, making it unsuitable for correcting various aberrations that occur throughout the entire zoom lens system. Furthermore, the zoom lens uses the second lens group, located closer to the object than the aperture, as the focus group. Because the focus group is located closer to the object side of the optical system, changes in image magnification become significant, which is undesirable for tracking AF and contrast AF. Furthermore, the second lens group is relatively heavy, making it difficult to achieve rapid focusing.

[0010] The present invention has been made in light of these circumstances, and aims to solve the above-mentioned problems and provide a zoom lens that allows the entire zoom lens to be made compact despite its large aperture and that effectively corrects various aberrations across the entire zoom range, as well as an imaging device equipped with the zoom lens. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the inventors have conducted extensive research and have come up with the following zoom lens and imaging device.

[0012] The zoom lens according to the present invention comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a rear group having at least one lens group, wherein the first lens group moves toward the object side when changing magnification from the wide-angle end to the telephoto end, and an aperture stop is located on the object side of the third lens group, and wherein the zoom lens is characterized by satisfying the following conditional expression: 0.90 ≦ Fnof ≦ 1.70 (1) 0.45 ≦ Bfw / fw ≦ 0.80 (2) 3.00 ≦ f1 / fw ≦ 6.00 (3) however, Fnof: the composite F-number of the first to fourth lens groups, which is the largest value in the entire magnification range from the wide-angle end to the telephoto end. Bfw: Back focus at the wide-angle end, which is the distance on the optical axis from the image side of the lens closest to the image to the image plane, and is the value when the cover glass thickness is converted into air fw: focal length of the entire zoom lens system at the wide-angle end f1: focal length of the first lens group

[0013] The imaging device according to the present invention employs an imaging device characterized by including the zoom lens described above and a solid-state imaging element that converts an optical image formed by the zoom lens into an electrical signal. [Effects of the Invention]

[0014] The zoom lens of the present invention has a large aperture, yet can achieve a compact size for the entire zoom lens, and can effectively correct various aberrations such as spherical aberration and coma over the entire zoom range. The imaging device of the present invention equipped with the zoom lens is compact, yet is capable of shooting at different focal lengths, and can take advantage of brightness and bokeh. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a zoom lens according to a first embodiment. [Figure 2] 1A to 1C are longitudinal aberration diagrams of Example 1 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens according to a second embodiment. [Figure 4] 10A to 10C are longitudinal aberration diagrams of Example 2 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens according to a third embodiment. [Figure 6] 10A to 10C are longitudinal aberration diagrams of Example 3 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 7]FIG. 10 is a cross-sectional view of a zoom lens according to a fourth embodiment. [Figure 8] 10A to 10C are longitudinal aberration diagrams of Example 4 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens according to a fifth embodiment. [Figure 10] 10A to 10C are longitudinal aberration diagrams of Example 5 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 11] FIG. 10 is a cross-sectional view of a zoom lens according to a sixth embodiment. [Figure 12] 13A to 13C are longitudinal aberration diagrams of Example 6 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. [Figure 13] FIG. 10 is a cross-sectional view of a zoom lens according to a seventh embodiment. [Figure 14] 13A to 13C are longitudinal aberration diagrams of Example 7 at the wide-angle end, at an intermediate focal position, and at the telephoto end when focusing on an object at infinity. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes embodiments of the zoom lens and the imaging device according to the present invention. Note that the following description merely shows one aspect, and should not be construed as being limited to the following description.

[0017] 1. Zoom Lens Embodiment 1-1.Optical configuration The zoom lens according to the present invention comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a rear group having at least one lens group. In this configuration, the first lens group moves toward the object side when changing magnification from the wide-angle end to the telephoto end.

[0018] In this zoom lens, a lens group is a group of lenses consisting of one or more lenses. A lens group is also a collection of lenses in which the spacing between adjacent lenses changes when zooming from the wide-angle end to the telephoto end. When a lens group is made up of multiple lenses, the relative positional relationship between the multiple lenses is maintained when zooming from the wide-angle end to the telephoto end. The lens group may be configured to be movable along the optical axis, or may be fixed.

[0019] The zoom lens may also have a cemented lens. An example of a cemented lens is one in which multiple lenses are integrated without any air gap between them. Another example of a cemented lens is one in which multiple lenses are integrated by bonding them together using a very thin adhesive that has no substantial optical effect. The number of lenses in a cemented lens refers to the number of lenses that are cemented together, and the adhesive layer is not counted as a lens. For example, a cemented lens in which two lenses are integrated together via an adhesive layer is counted as two lenses. The configuration of each lens group will be described below.

[0020] (1) First lens group The first lens group is the lens group closest to the object and has positive refractive power as a whole. The lens configuration of the first lens group is not particularly limited, as long as it has positive refractive power as a whole. For example, if the first lens group is configured to include two lenses with positive refractive power, a strong positive refractive power can be provided in the first lens group. In this case, a high zoom ratio can be achieved while enhancing the telephoto tendency at the telephoto end, making it easier to reduce the size of the entire system. Note that a strong telephoto tendency refers to a telephoto ratio less than 1. Furthermore, a configuration including at least one lens with negative refractive power facilitates correction of spherical aberration, chromatic aberration, and other aberrations, making it more preferable for achieving a zoom lens with excellent optical performance.

[0021] (2) Second lens group The second lens group has negative refractive power as a whole. The lens configuration of the second lens group is not particularly limited, as long as it has negative refractive power as a whole. For example, if the second lens group is configured to include two or more lenses with negative refractive power and one or more lenses with positive refractive power, a strong negative refractive power can be disposed within the second lens group. In this case, the zoom ratio of the second lens group can be increased, making it easy to achieve a high zoom ratio and excellent optical performance. Furthermore, it is preferable that the lens surface of the second lens group closest to the object side is convex toward the object side. This makes it easy to effectively correct field curvature at the wide-angle end.

[0022] (3) Third lens group The third lens group has positive refractive power as a whole. Possessing positive refractive power throughout the third lens group enables convergence of light beams, making it easier to realize a zoom lens with a large aperture ratio and a compact size. The third lens group is not particularly limited in its lens configuration as long as it has positive refractive power as a whole. However, it preferably has at least two lenses with positive refractive power and at least one lens with negative refractive power. Here, it is necessary to correct spherical aberration and curvature of field in the under-focus direction, which occurs when a strong positive refractive power is disposed within the third lens group. Therefore, by disposing at least one lens with negative refractive power and a concave object-side surface within the third lens group, it becomes easier to effectively correct spherical aberration throughout the entire zoom range and fluctuations in curvature of field due to changes in object distance. The lens with negative refractive power and a concave object-side surface may be a cemented lens with another lens.

[0023] (4) Fourth lens group The fourth lens group has positive refractive power as a whole. Possessing positive refractive power as a whole enables convergence of light beams, making it easy to realize a zoom lens with a large aperture ratio and a compact size. The fourth lens group is not particularly limited in its lens configuration as long as it has positive refractive power as a whole, but it preferably has at least one lens with positive refractive power and at least one lens with negative refractive power. This configuration makes it easy to ensure a bright F-number for the entire zoom lens system.

[0024] (5) Posterior group The rear group includes at least one lens group, and is configured from a lens group located between the image side of the fourth lens group and the image plane. The rear group also includes at least one focus group having negative refractive power and moving along the optical axis. Since the light beam converged by the third and fourth lens groups is incident on the focus group, the diameter of the lenses arranged within the focus group can be reduced, and the focus group can be easily made lightweight. As a result, high-speed focusing can be achieved, and the load on the focus drive system can be easily reduced.

[0025] The focus group is not particularly limited in its specific lens configuration as long as it has negative refractive power as a whole, but it is preferable that it be configured with only one lens having negative refractive power, or with only a cemented lens in which one lens having negative refractive power and one lens having positive refractive power are cemented together. Such a configuration makes it easy to achieve high-speed focusing by reducing the weight of the focus group, and to obtain a high-performance zoom lens in which various aberrations such as spherical aberration and chromatic aberration are well corrected over the entire object distance.

[0026] The rear group preferably has one lens group closer to the image side than the focus group, and the refractive power of that lens group may be positive or negative. The configuration of that lens group is not particularly limited, but it is preferable that it has at least one lens with positive refractive power and at least one lens with negative refractive power.

[0027] The rear group may include three or more lens groups, but since it becomes difficult to achieve compactness when the number of lens groups constituting a zoom lens is large, it is preferable that the rear group be composed of two lens groups.

[0028] (6) Aperture diaphragm In this zoom lens, the location of the aperture stop is not particularly limited. The aperture stop here refers to an aperture stop that determines the light beam diameter of the optical system, i.e., the F-number of the optical system. Generally, if the height of off-axial rays passing through the lenses constituting the optical system is high, i.e., if the distance from the optical axis at which the off-axial rays pass through the lenses is long, the amount of off-axial aberration that occurs tends to increase, making aberration correction difficult. Therefore, unless there are special circumstances that require the aperture stop to be located on the object side or image side of the optical system, it is preferable to locate the aperture stop near the center of the optical system.

[0029] It is preferable to locate the aperture stop adjacent to the object side of the third lens group. This configuration makes it easy to reduce the effective light beam diameter of the first lens group at the wide-angle end, which makes it easy to reduce the size of the entire zoom lens.

[0030] By adopting the above configuration, it is possible to realize a compact zoom lens despite having a large aperture, and various aberrations such as spherical aberration and coma can be corrected satisfactorily over the entire zoom range.

[0031] 1-2.Operation 1-2-1. Operation when changing magnification In this zoom lens, the spacing between adjacent lens groups changes when changing magnification from the wide-angle end to the telephoto end. As long as the spacing between each lens group changes, all of the lens groups may move in the optical axis direction, or some of the lens groups may be fixed as fixed groups in the optical axis direction and other lens groups may be movable groups that move in the optical axis direction.

[0032] When changing magnification from the wide-angle end to the telephoto end, there are no particular restrictions on whether each lens group moves or is fixed, but it is preferable to move the first, third, fourth lens group, and focus group toward the object side. By moving these lens groups toward the object side, it is possible to prevent strain on the magnification function of each lens group closer to the image side than the second lens group, resulting in a configuration that easily achieves both a good magnification ratio and high performance.

[0033] It is preferable that the second lens group be moved toward the image side when changing magnification from the wide-angle end to the telephoto end. By moving the second lens group toward the image side, the diameter of the light beam incident on the third and fourth lens groups at the telephoto end can be reduced. This allows the diameter of the aperture stop to be reduced, making it easier to achieve a compact zoom lens overall.

[0034] The lens group located closest to the image in the rear group may move in the optical axis direction when changing magnification from the wide-angle end to the telephoto end, or may be fixed in the optical axis direction. If the lens group located in the rear group moves when changing magnification from the wide-angle end to the telephoto end, the magnification effect of the rear group can be improved. In this case, the amount of movement of each lens group other than the rear group can be reduced, making it easier to achieve a more compact zoom lens with a high zoom ratio. Furthermore, if a group located in the rear group is fixed in the optical axis direction when changing magnification from the wide-angle end to the telephoto end, it is possible to avoid complicating the cam structure of the lens barrel that constitutes the zoom lens, which is advantageous in constructing a zoom lens.

[0035] 1-2-2.Focus operation In this zoom lens, focusing from an object at infinity to an object at a finite distance is preferably performed by moving the focus group located in the rear group toward the image in the optical axis direction. Because the light beam converged by the third and fourth lens groups is incident on this focus group, the diameter of the lenses located in the focus group can be reduced, and the focus group can be made lighter. As a result, high-speed focusing can be achieved, and the load on the focus drive system can be easily reduced. Furthermore, fluctuations in the angle of view that occur when moving the focus group can be suppressed. Therefore, a zoom lens suitable for video capture using a tracking AF function can be obtained, not only when a contrast AF system is used, but also when an image plane phase-difference AF system is used.

[0036] 1-3.Conditional Expressions The zoom lens preferably employs the above-described configuration and satisfies one or more of the following conditional expressions.

[0037] 1-3-1.Conditional Expression (1) 0.90 ≦ Fnof ≦ 1.70 (1) however, Fnof: The composite F-number from the first lens group to the fourth lens group, which is the largest value in the entire magnification range from the wide-angle end to the telephoto end.

[0038] Conditional expression (1) is a condition for appropriately setting the largest combined F-number of the first to fourth lens groups over the entire zoom range from the wide-angle end to the telephoto end. By satisfying conditional expression (1), it becomes easy to ensure the desired brightness of the zoom lens.

[0039] If the value of Fnof in conditional formula (1) falls below the lower limit, the combined F-number from the first lens group to the fourth lens group becomes too small, making it difficult to effectively correct various aberrations, which is undesirable. On the other hand, if the value of Fnof in conditional formula (1) exceeds the upper limit, it becomes difficult to ensure the desired brightness. In this case, in order to obtain the desired brightness, it is necessary to impart strong positive refractive power to the rear group, which requires an increase in the number of lens groups and a corresponding increase in the number of lenses, making it difficult to shorten the overall length and make the zoom lens compact, which is undesirable.

[0040] In order to obtain the above effects, the lower limit of conditional expression (1) is more preferably 0.92, and may be set to 0.94, 0.96, 0.98, 1.00, 1.02, 1.04, 1.06, 1.08, or 1.10. The upper limit of conditional expression (1) is more preferably 1.69, and may be set to 1.68, 1.67, 1.66, 1.65, 1.64, 1.63, 1.62, 1.61, 1.60, 1.59, 1.58, 1.57, or 1.56.

[0041] When adopting these preferable lower limit values ​​or upper limit values, the inequality sign with equality (≦) may be replaced with the inequality sign (<), and vice versa. The same applies to other conditional expressions described below.

[0042] 1-3-2.Conditional Expression (2) 0.45 ≦ Bfw / fw ≦ 0.80 (2) however, Bfw: Back focus at the wide-angle end, which is the distance on the optical axis from the image side of the lens closest to the image to the image plane, and is the value when the cover glass thickness is converted into air fw: focal length of the entire zoom lens system at the wide-angle end

[0043] Conditional expression (2) defines the ratio between the back focal length of the zoom lens at the wide-angle end and the focal length of the entire zoom lens system at the wide-angle end. By satisfying conditional expression (2), the back focal length of the zoom lens at the wide-angle end can be shortened, and the overall length of the zoom lens can be reduced.

[0044] If the value of Bfw / fw in conditional formula (2) falls below the lower limit, the back focal length of the zoom lens at the wide-angle end becomes too short, which increases the inclination angle of incident light on the image plane relative to the optical axis. This increases the angle of incidence of the chief ray beyond the allowable angle of incidence of the on-chip microlenses provided for each pixel on the light-receiving surface of the image sensor, resulting in insufficient peripheral illumination or shading, which is undesirable. On the other hand, if the value of Bfw / fw in conditional formula (2) exceeds the upper limit, the back focal length of the zoom lens at the wide-angle end becomes too long, making it difficult to reduce the overall length of the zoom lens. This increases the size of the optical system, which is undesirable for small image pickup devices that do not require a reflex mirror, such as mirrorless single-lens cameras.

[0045] In order to obtain the above effects, the lower limit of conditional expression (2) is more preferably 0.46, and may be set to 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, or 0.53. The upper limit of conditional expression (2) is more preferably 0.79, and may be set to 0.78, 0.77, 0.76, 0.75, 0.74, 0.73, 0.72, 0.71, 0.70, or 0.69.

[0046] 1-3-3.Conditional Expression (3) 3.00 ≦ f1 / fw ≦ 6.00 (3) however, f1: focal length of the first lens group fw: focal length of the entire zoom lens system at the wide-angle end

[0047] Conditional expression (3) defines the ratio between the focal length of the first lens group and the focal length of the entire zoom lens system at the wide-angle end. Satisfying conditional expression (3) makes it easy to ensure a predetermined angle of view at the wide-angle end. At the same time, it is possible to limit the amount of movement of the first lens group during zooming within an appropriate range, and shorten the overall optical length of the zoom lens at the telephoto end. Furthermore, it is possible to achieve high optical performance throughout the entire zoom range while ensuring a predetermined zoom ratio, and to reduce the size of the zoom lens.

[0048] If the value of f1 / fw in conditional expression (3) falls below the lower limit, the amount of movement of the first lens group during zooming can be reduced, but it becomes difficult to ensure a predetermined angle of view at the wide-angle end. In this case, to ensure a predetermined angle of view at the wide-angle end, it is necessary to strengthen the refractive power of each lens group arranged closer to the image plane than the first lens group. Strengthening the refractive power of each lens group makes it difficult to correct aberrations, which is undesirable because it makes it difficult to achieve a compact zoom lens with high optical performance. On the other hand, if the value of f1 / fw in conditional expression (3) exceeds the upper limit, it becomes easier to correct aberrations, but the amount of movement of the first lens group during zooming increases. Therefore, to ensure a predetermined zoom ratio, the total optical length at the telephoto end becomes long, which is undesirable in terms of achieving a compact zoom lens.

[0049] In order to obtain the above effects, the lower limit of conditional expression (3) is more preferably 3.05, and may be set to 3.10, 3.15, 3.20, 3.25, 3.30, 3.35, 3.40, 3.45, 3.50, 3.55, or 3.60. The upper limit of conditional expression (3) is more preferably 5.95, and may be set to 5.90, 5.85, 5.80, 5.75, 5.70, 5.65, 5.60, 5.55, or 5.50.

[0050] 1-3-4.Conditional Expression (4) -5.000 ≦ (RF+RB) / (RF-RB) ≦ -0.005 ···(4) however, RF: Radius of curvature of the object-side lens surface in contact with air in a single lens or cemented lens whose object-side surface is concave RB: Radius of curvature of the image-side lens surface in contact with air in a single lens or cemented lens whose object-side surface is concave

[0051] Conditional expression (4) is a conditional expression that defines the radius of curvature of the object-side lens surface that contacts air and the radius of curvature of the image-side lens surface that contacts air in a single lens or cemented lens with a concave object-side surface that is located in the lens group that has positive refractive power and is closest to the object among the lens groups that are located closer to the image than the aperture stop position. Satisfying conditional expression (4) makes it possible to effectively correct spherical aberration and curvature of field that occur in the lens group that has positive refractive power and is closest to the object among the lens groups that are located closer to the image than the aperture stop position. It also makes it possible to reduce the size of the focus group located in the rear group.

[0052] If the value of (RF+RB) / (RF-RB) in conditional expression (4) falls below the lower limit, the value of RF becomes too small, which makes it easier for high-order aberrations to occur and increases the sensitivity to decentering between the lenses, which is undesirable. On the other hand, if the value of (RF+RB) / (RF-RB) in conditional expression (4) exceeds the upper limit, the value of RF becomes too large, which makes it difficult to correct spherical aberrations and curvature of field, which is undesirable. In addition, this is disadvantageous for reducing the size of the focus group disposed in the rear group.

[0053] In order to obtain the above-mentioned effect, the lower limit of conditional expression (4) is more preferably -4.990, and may be set to -4.980, -4.970, -4.960, -4.950, -4.940, -4.930, -4.920, -4.910, or -4.900. The upper limit of conditional expression (4) is more preferably -0.010, and may be set to -0.020, -0.030, -0.040, -0.050, -0.055, -0.060, -0.065, -0.070, -0.075, or -0.080.

[0054] 1-3-5.Conditional Expression (5) 1.30 ≦ β2t / β2w ≦ 1.85 (5) however, β2t: Lateral magnification of the second lens group when focusing at infinity at the telephoto end β2w: Lateral magnification of the second lens group when focusing on infinity at the wide-angle end

[0055] Conditional expression (5) defines the ratio between the lateral magnification of the second lens group when focusing on infinity at the telephoto end and the lateral magnification of the second lens group when focusing on infinity at the wide-angle end. By satisfying conditional expression (5), it is possible to achieve a high zoom ratio while configuring the zoom lens with a small number of lenses.

[0056] If the value of β2t / β2w in conditional expression (5) falls below the lower limit, it becomes difficult to obtain the desired zoom ratio. Furthermore, in this case, to obtain the desired zoom ratio, it is necessary to increase the zoom ratio with the lens group closer to the image side than the second lens group, which requires an increase in the number of lenses, which is undesirable. On the other hand, if the value of β2t / β2w in conditional expression (5) exceeds the upper limit, it becomes easy to achieve a high zoom ratio, but it becomes difficult to effectively correct various aberrations, which is undesirable.

[0057] In order to obtain the above effects, the lower limit of conditional expression (5) is more preferably 1.31, and may be set to 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, or 1.38. The upper limit of conditional expression (5) is more preferably 1.84, and may be set to 1.83, 1.82, 1.81, 1.80, 1.79, 1.75, or 1.74.

[0058] 1-3-6.Conditional Expression (6) 0.00 < f3m / fw ≦ 0.50 (6) however, f3m: The difference in movement between the wide-angle end position of the third lens group and the telephoto end position of the third lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative fw: focal length of the entire zoom lens system at the wide-angle end

[0059] Conditional expression (6) defines the ratio of the difference in movement between the wide-angle end position of the third lens group and the telephoto end position of the third lens group when changing magnification from the wide-angle end to the telephoto end to the focal length of the entire zoom lens system at the wide-angle end. Satisfying conditional expression (6) makes it possible to limit the increase in the outer diameter of the aperture stop and the adjacent third lens group, which is advantageous for making the entire product system more compact.

[0060] If the value of f3m / fw in conditional expression (6) is below the lower limit, the magnification effect of the third lens group cannot be obtained, making it difficult to achieve the desired focal length, which is undesirable. On the other hand, if the value of f3m / fw in conditional expression (6) is above the upper limit, the amount of movement of the third lens group increases. This also reduces the positive refractive power of the third lens group, which undesirably increases the size of the aperture stop and the adjacent third lens group, and therefore the size of the entire zoom lens.

[0061] In order to obtain the above effects, the lower limit of conditional expression (6) is more preferably 0.02 or more, and may be set to 0.04 or more, 0.06 or more, 0.08 or more, 0.10 or more, 0.12 or more, 0.14 or more, 0.16 or more, 0.18 or more, 0.20 or more, 0.22 or more, 0.24 or more, 0.26 or more, 0.28 or more, or 0.30 or more. The upper limit of conditional expression (6) is more preferably 0.49, and may be set to 0.48, 0.47, 0.46, 0.45, 0.44, 0.43, 0.42, 0.41, or 0.40.

[0062] 1-3-7.Conditional Expression (7) 15.00 ≦ ν1 ≦ 30.00 (7) however, ν1: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the position of the aperture stop

[0063] Conditional expression (7) defines the Abbe number of a lens having positive refractive power in a lens group having positive refractive power that is located closer to the image than the aperture stop. By including at least one lens that satisfies conditional expression (7), it becomes possible to effectively correct axial chromatic aberration and lateral chromatic aberration that occur in the zoom lens.

[0064] If the value of v1 in conditional formula (7) falls below the lower limit, the anomalous dispersion generated by the lens in question will become stronger, and the occurrence of chromatic aberration for the g-line will become more pronounced, raising concerns about coloring of out-of-focus images and the occurrence of peripheral coma flare, which is undesirable. On the other hand, if the value of v1 in conditional formula (7) exceeds the upper limit, it will become impossible to sufficiently correct axial chromatic aberration and lateral chromatic aberration, and the resulting large chromatic aberration will make the lens unsuitable for achieving a high-performance zoom lens, which is undesirable.

[0065] In order to obtain the above effects, the lower limit of conditional expression (7) is more preferably 15.50, and may be set to 16.00, 16.50, 17.00, or 17.50. The upper limit of conditional expression (7) is more preferably 29.00, and may be set to 28.00, 27.00, 26.00, 25.00, 24.00, or 23.00.

[0066] 1-3-8.Conditional Expression (8) 66.00 ≦ ν2 ≦ 98.55 (8) however, ν2: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the aperture stop position

[0067] Conditional formula (8) defines the Abbe number of a lens with positive refractive power in a lens group with positive refractive power that is located closer to the image side than the aperture stop. By including at least one lens that satisfies conditional formula (8), it becomes possible to effectively correct axial chromatic aberration, which is important in optical systems with fast F-numbers. By placing this lens in a lens group that increases the axial ray diameter of the entire zoom lens system, it becomes possible to correct axial chromatic aberration. This makes it possible to realize a zoom lens with higher performance.

[0068] If the value of v2 in conditional expression (8) is below the lower limit, correction of axial chromatic aberration becomes insufficient, raising concerns about the occurrence of axial chromatic aberration, which is undesirable. On the other hand, if the value of v2 in conditional expression (8) is above the upper limit, correction of axial chromatic aberration in lenses other than the relevant lens element becomes necessary, which increases the number of lens elements and is therefore unsuitable for reducing the weight of the product, which is undesirable.

[0069] In order to obtain the above-mentioned effects, the lower limit of conditional expression (8) is more preferably 66.50, and may be set to 67.00, 67.50, 67.90, 68.00, or 68.50. The upper limit of conditional expression (8) is more preferably 98.00, and may be set to 97.50, 97.00, 96.50, 96.00, or 95.50.

[0070] 1-3-9.Conditional Expression (9) 10 ≦ N ≦ 25 (9) however, N: The total number of lenses located on the image side of the aperture stop

[0071] Conditional expression (9) defines the total number of lenses to be arranged on the image side of the aperture stop. Satisfying conditional expression (9) makes it possible to effectively correct various aberrations and is advantageous for making the entire zoom lens system compact.

[0072] If the value of N in conditional expression (9) is below the lower limit, it is advantageous for the overall zoom lens system to be compact, but the aberration correction effect in the lens group located on the image side of the aperture stop becomes insufficient, making it difficult to realize a high-performance zoom lens, which is undesirable.On the other hand, if the value of N in conditional expression (9) is above the upper limit, it is advantageous for the correction of various aberrations because a large number of lenses are located on the image side of the aperture stop, but it is undesirable because the large number of lenses increases the overall size of the zoom lens system.

[0073] In order to obtain the above effect, it is more preferable that the lower limit of conditional expression (9) is 11. It is also more preferable that the upper limit of conditional expression (8) is 23, and it may be set to 22, 21, 20, 19, 18, 17, 16, 15, or 14.

[0074] 1-3-10.Conditional Expression (10) 0.05 ≦ f1 / f3 ≦ 4.50 (10) however, f1: focal length of the first lens group f3: focal length of the third lens group

[0075] Conditional expression (10) defines the ratio between the focal length of the first lens group and the focal length of the third lens group. By satisfying conditional expression (10), it is possible to achieve a compact and lightweight zoom lens system.

[0076] When the value of f1 / f3 in conditional expression (10) falls below the lower limit, the positive refractive power of the first lens group becomes stronger, which is advantageous for reducing the size of the overall refractive power arrangement of the zoom lens. However, when the refractive power of the first lens group becomes stronger, the lens group closer to the image side than the first lens group needs to correct aberrations to compensate for the increased refractive power of the first lens group, which can lead to concerns such as an increase in the number of lenses, making this undesirable and unsuitable for reducing the size and weight of the entire product. On the other hand, when the value of f1 / f3 in conditional expression (10) exceeds the upper limit, the positive refractive power of the first lens group becomes weaker, which can lead to concerns such as an increase in the overall length of the zoom lens, which is undesirable and disadvantageous for reducing the size of the entire zoom lens.

[0077] In order to obtain the above-mentioned effects, the lower limit of conditional expression (10) is more preferably 0.10, and may be set to 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, or 0.50. The upper limit of conditional expression (10) is more preferably 4.40, and may be set to 4.30, 4.20, 4.10, 4.00, 3.90, 3.80, 3.70, 3.60, or 3.50.

[0078] 1-3-11.Conditional Expression (11) 0.01 ≦ f3 / f4 ≦ 12.00 (11) however, f3: focal length of the third lens group f4: focal length of the fourth lens group

[0079] Conditional expression (11) defines the ratio between the focal length of the third lens group and the focal length of the fourth lens group. By satisfying conditional expression (11), a desired F-number can be achieved for the zoom lens, and the outer diameter of the zoom lens and the diameter of the focus group unit located after the fourth lens group can be reduced.

[0080] If the value of f3 / f4 in conditional expression (11) falls below the lower limit, the positive refractive power of the third lens group becomes stronger, which is advantageous for reducing the diameters of the aperture stop and the third lens group. However, the third lens group becomes more sensitive to decentering. Furthermore, aberration correction becomes necessary in the lens group closer to the image side than the fourth lens group, which can lead to concerns about an increase in the number of lenses, making this unsuitable for reducing the size and weight of the entire product, which is undesirable. On the other hand, if the value of f3 / f4 in conditional expression (11) exceeds the upper limit, the positive refractive power of the third lens group becomes weaker, which increases the beam diameter of the third lens group and enlarges the diameter of the aperture stop adjacent to the third lens group. Therefore, this is unsuitable for reducing the size and weight of the lens, which is undesirable.

[0081] In order to obtain the above effects, the lower limit of conditional expression (11) is more preferably 0.02, and may be set to 0.04, 0.06, 0.08, 0.10, or 0.12. The upper limit of conditional expression (11) is more preferably 11.80, and may be set to 11.60, 11.40, 11.20, 11.00, 10.80, 10.60, 10.40, 10.20, 10.00, 9.80, 9.60, 9.40, 9.20, or 9.00.

[0082] 1-3-12.Conditional Expression (12) 10.00 ≦ Fwf ≦ 35.00 (12) however, Fwf: the composite focal length of the lens group located closer to the object than the lens group with negative refractive power that is adjacent to the lens group with positive refractive power that is located closer to the image than the aperture stop position at the wide-angle end

[0083] Conditional expression (12) defines the composite focal length of the lens group at the wide-angle end, which is located closer to the object than the lens group with negative refractive power that is adjacent to the lens group with positive refractive power that is located closer to the image than the aperture stop. Here, the "lens group with negative refractive power that is adjacent to the lens group with positive refractive power that is located closer to the image than the aperture stop" corresponds to the focus group of the zoom lens. Satisfying conditional expression (12) makes it possible to reduce the overall size of the zoom lens, and by optimizing the light beam incident on the focus group, it becomes possible to make the focus group smaller and lighter. Furthermore, it becomes easier to ensure the desired brightness.

[0084] If the value of Fwf in conditional expression (12) falls below the lower limit, the composite focal length on the object side of the focus group will become shorter, which is advantageous for reducing the size of the entire zoom lens system, but it is undesirable because aberration correction in the lens group on the image side of the focus group will become insufficient, making it difficult to achieve a high-performance zoom lens.On the other hand, if the value of Fwf in conditional expression (12) exceeds the upper limit, the diameter of the light beam incident on the focus group will become large, which is undesirable because the diameter of the focus group will become large.

[0085] In order to obtain the above-mentioned effects, the lower limit of conditional expression (12) is more preferably 10.50, and may be set to 11.00, 11.50, 12.00, 12.50, 13.00, 13.50, 14.00, or 14.50. The upper limit of conditional expression (12) is more preferably 34.50, and may be set to 34.00, 33.50, 33.00, 32.50, 32.00, 31.50, 31.00, 30.50, 30.00, 29.00, 28.00, 27.00, 26.00, 25.00, or 24.00.

[0086] 1-3-13.Conditional Expression (13) -2.00 ≦ f1m / f2m ≦ -0.02 ···(13) however, f1m: The difference in the amount of movement between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative f2m: The difference in the amount of movement between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative.

[0087] Conditional expression (13) defines the ratio of the difference in the amount of movement between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end to the difference in the amount of movement between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end. By satisfying conditional expression (13), it is possible to provide a zoom lens with little movement over its entire length.

[0088] If the value of f1m / f2m in conditional expression (13) falls below the lower limit, the amount of movement of the first lens group increases, making it difficult to provide a zoom lens with little movement over its entire length, which is undesirable. On the other hand, if the value of f1m / f2m in conditional expression (13) exceeds the upper limit, the amount of movement of the first lens group decreases, making it easier to provide a zoom lens with little movement over its entire length, but the positive refractive power of the first lens group weakens, raising concerns about an increase in the overall length of the zoom lens, which is undesirable as it is disadvantageous for making the product more compact.

[0089] In order to obtain the above-mentioned effects, the lower limit of conditional expression (13) is more preferably -1.90, and may be set to -1.80, -1.70, -1.60, -1.50, -1.40, -1.30, -1.20, -1.10, or -1.00. The upper limit of conditional expression (13) is more preferably -0.05, and may be set to -0.10, -0.15, -0.20, -0.25, -0.30, -0.35, -0.40, -0.45, or -0.50.

[0090] 1-3-14.Conditional Expression (14) 7.05 ≦ Lw / f1m ≦ 20.00 (14) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. f1m: The difference in the amount of movement between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0091] Conditional expression (14) defines the ratio of the distance from the lens surface closest to the object at the wide-angle end to the image plane to the amount of movement of the first lens group at the wide-angle end and the difference between the position of the first lens group at the telephoto end when changing magnification from the wide-angle end to the telephoto end. Satisfying conditional expression (14) makes it possible to realize a zoom lens with little movement of the center of gravity during magnification change, which is advantageous for reducing the size of the entire zoom lens in the magnification change range.

[0092] If the value of Lw / f1m in conditional expression (14) falls below the lower limit, it is advantageous for aberration correction, but the amount of movement of the first lens group during zooming increases. Therefore, to ensure a predetermined zoom ratio, the overall optical length at the telephoto end becomes long, which is undesirable in terms of compactness of the zoom lens. On the other hand, if the value of Lw / f1m in conditional expression (14) exceeds the upper limit, it is possible to reduce the amount of movement of the first lens group during zooming, which is advantageous in terms of shortening the overall optical length of the zoom lens at the telephoto end. However, it becomes difficult to ensure a predetermined angle of view at the wide-angle end. To ensure a predetermined angle of view at the wide-angle end, it is necessary to strengthen the refractive power of each lens group located closer to the image plane than the first lens group. Strengthening the refractive power of each lens group makes it difficult to correct aberrations, which is undesirable in terms of achieving a compact zoom lens with high optical performance.

[0093] In order to obtain the above-mentioned effects, the lower limit of conditional expression (14) is more preferably 7.10, and may be set to 7.20, 7.30, 7.40, 7.50, 7.60, 7.70, 7.80, 7.90, 8.00, 8.50, or 9.00. The upper limit of conditional expression (14) is more preferably 19.85, and may be set to 19.70, 19.55, 19.40, 19.25, 19.10, 18.95, 18.80, 18.65, 18.50, 18.35, 18.20, 18.05, 17.90, 17.80, 17.70, or 17.60.

[0094] 1-3-15.Conditional Expression (15) 0.000 < f1m / fw ≦ 0.750 (15) however, f1m: The difference in the amount of movement between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative fw: focal length of the entire zoom lens system at the wide-angle end

[0095] Conditional expression (15) defines the ratio of the difference in movement between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end to the focal length of the entire zoom lens system at the wide-angle end. By satisfying conditional expression (15), a zoom lens with little change in overall length can be realized, and fluctuations in field curvature that occur when changing magnification can be effectively corrected.

[0096] If the value of f1m / fw in conditional expression (15) is below the lower limit, the amount of movement of the first lens group becomes small, and therefore it is necessary to strengthen the positive refractive power of the first lens group to obtain the desired zoom ratio. As a result, fluctuations in field curvature and the like increase during zooming, which is undesirable as it becomes difficult to reduce this. On the other hand, if the value of f1m / fw in conditional expression (15) exceeds the upper limit, the amount of movement of the first lens group increases, which is undesirable as the entire zoom lens system becomes larger.

[0097] In order to obtain the above-mentioned effects, the lower limit of conditional expression (15) is more preferably 0.050 or more, and may be set to 0.100 or more, 0.150 or more, 0.200 or more, 0.250 or more, or 0.300 or more. The upper limit of conditional expression (15) is more preferably 0.725, and may be set to 0.700, 0.675, 0.650, 0.625, or 0.600.

[0098] 1-3-16.Conditional Expression (16) -0.95 ≦ f2m / fw ≦ -0.13 ···(16) however, f2m: The difference in the amount of movement between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative. fw: focal length of the entire zoom lens system at the wide-angle end

[0099] Conditional expression (16) defines the ratio of the difference in the amount of movement between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end to the focal length of the entire zoom lens system at the wide-angle end. By satisfying conditional expression (16), it becomes easy to make the entire zoom lens system compact, even with a large aperture.

[0100] If the value of f2m / fw in conditional expression (16) falls below the lower limit, the amount of movement of the second lens group increases. In this case, the negative refractive power of the second lens group decreases, and to achieve the desired F-number, it is necessary to increase the size of the lens group closer to the image than the second lens group, which undesirably increases the size of the entire zoom lens. On the other hand, if the value of f2m / fw in conditional expression (16) exceeds the upper limit, the amount of movement of the second lens group decreases. In this case, the negative refractive power of the second lens group increases, which is advantageous for reducing the lens diameter, but there is a concern that the number of lenses will increase and the lens group configuration will become larger because various aberrations generated in the second lens group will have to be corrected by a lens group closer to the image than the third lens group. This is undesirable because it is not suitable for shortening the overall lens length and reducing the product weight.

[0101] In order to obtain the above-mentioned effect, the lower limit of conditional expression (16) is more preferably -0.93 and may be set to -0.91, -0.89, -0.87, -0.85, -0.83, -0.81, -0.79, -0.77, or -0.75. The upper limit of conditional expression (16) is more preferably -0.15 and may be set to -0.17, -0.19, -0.21, -0.23, -0.25, -0.27, -0.29, -0.31, -0.33, -0.35, -0.37, or -0.39.

[0102] 1-3-17.Conditional Expression (17) -3.00 ≦ β4t / β4w ≦ 3.00 ···(17) however, β4t: Lateral magnification of the fourth lens group when focusing at infinity at the telephoto end β4w: Lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end

[0103] Conditional expression (17) defines the ratio between the lateral magnification of the fourth lens group when focusing on infinity at the telephoto end and the lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end. Satisfying conditional expression (17) makes it possible to reduce the size of the lens groups closer to the image side than the third and fourth lens groups.

[0104] If the value of β4t / β4w in conditional expression (17) falls below the lower limit, the zoom ratio of the fourth lens group will be small, and therefore, in order to obtain a desired zoom ratio, it will be necessary to increase the zoom ratios of the third lens group and the other lens groups, which makes it difficult to correct aberrations that occur within and between the lens groups, which is undesirable. On the other hand, if the value of β4t / β4w in conditional expression (17) exceeds the upper limit, the zoom ratio of the fourth lens group will be large, which is advantageous for reducing the size of the lens group that is closer to the image than the fourth lens group, but it is undesirable because the positive refractive power of the fourth lens group will be strong, making it difficult to correct spherical aberrations and to correct image plane fluctuations during zooming.

[0105] In order to obtain the above-mentioned effect, the lower limit of conditional expression (17) is more preferably -2.90, and may be set to -2.80, -2.70, -2.60, -2.50, -2.40, -2.30, -2.20, -2.10, -2.00, -1.90, -1.80, -1.70, or -1.60. The upper limit of conditional expression (17) is more preferably 2.90, and may be set to 2.80, 2.70, 2.60, 2.50, 2.40, 2.30, 2.20, 2.10, 2.00, 1.90, 1.80, 1.70, or 1.60.

[0106] 1-3-18.Conditional Expression (18) 1.600 ≦ Nd_G1ave ≦ 1.780 ···(18) however, Nd_G1ave: The average value of the refractive index at the d line of the glass material of each lens that makes up the first lens group

[0107] Conditional expression (18) defines the average value of the refractive index at the d-line of the glass material of each lens constituting the first lens group. By satisfying conditional expression (18), it is possible to make the first lens group smaller and thinner.

[0108] If the value of Nd_G1ave in conditional expression (18) falls below the lower limit, the thickness of the lens having a positive refractive index included in the first lens group must be increased in order to ensure the edge thickness of the lens having a positive refractive index. As a result, it becomes difficult to make the first lens group thinner, which is undesirable. On the other hand, if the value of Nd_G1ave in conditional expression (18) exceeds the upper limit, the Abbe number at the d-line becomes small with currently available lens materials, which makes it difficult to correct axial chromatic aberration and lateral chromatic aberration over the entire magnification range, which is undesirable.

[0109] In order to obtain the above effect, the lower limit of conditional expression (18) is more preferably 1.605, and may be set to 1.610, 1.615, 1.620, 1.625, 1.630, 1.635, 1.640, 1.645, 1.650, 1.655, or 1.660. The upper limit of conditional expression (18) is more preferably 1.775, and may be set to 1.770, 1.765, 1.760, 1.755, 1.750, 1.745, 1.740, 1.735, 1.730, 1.725, or 1.720.

[0110] 1-3-19.Conditional Expression (19) 5.50 ≦ Lw / Yw ≦ 8.50 (19) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. Yw: Maximum image height when focused at infinity at the wide-angle end

[0111] Conditional expression (19) is a conditional expression for setting an appropriate distance from the lens surface closest to the object at the wide-angle end to the image plane with respect to the maximum image height when focusing at infinity at the wide-angle end. By satisfying conditional expression (19), it is possible to achieve both a reduction in the overall optical length of the zoom lens at the wide-angle end and high performance.

[0112] If the value of Lw / Yw in conditional expression (19) falls below the lower limit, the overall optical length of the zoom lens at the wide-angle end may become too short relative to the maximum image height when focusing at infinity at the wide-angle end. This is undesirable because a short overall optical length of the zoom lens makes it difficult to correct aberrations that occur in each lens group. On the other hand, if the value of Lw / Yw in conditional expression (19) exceeds the upper limit, the overall optical length of the zoom lens at the wide-angle end may become too long relative to the maximum image height when focusing at infinity at the wide-angle end. This long overall optical length of the zoom lens increases the overall size and weight of the zoom lens, which is undesirable.

[0113] In order to obtain the above-mentioned effect, the lower limit of conditional expression (19) is more preferably 5.60, and may be set to 5.70, 5.80, 5.90, 6.00, 6.10, 6.20, 6.30, 6.40, 6.50, 6.60, 6.70, 6.80, 6.90, or 7.00. The upper limit of conditional expression (19) is more preferably 8.45, and may be set to 8.40, 8.35, 8.30, 8.25, 8.20, 8.15, 8.10, 8.05, 8.00, 7.95, or 7.90.

[0114] 2. Imaging Device The imaging device according to the present invention includes the zoom lens according to the present invention described above and a solid-state imaging element that converts an optical image formed by the zoom lens into an electrical signal. The solid-state imaging element is not particularly limited as long as it can convert an optical image into an electrical signal, and a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used. Suitable imaging devices include digital still cameras and digital video cameras, but particularly suitable imaging devices include interchangeable lens imaging devices such as single-lens reflex cameras and mirrorless cameras.

[0115] The zoom lens of the present invention has a large aperture, yet can be made compact, and can effectively correct various aberrations, such as spherical aberration and coma, across the entire zoom range. Therefore, the imaging device of the present invention equipped with the zoom lens is compact, yet capable of shooting at different focal lengths, and can take advantage of brightness and bokeh.

[0116] The embodiment of the present invention described above is one aspect of the present invention, and can be modified as appropriate without departing from the spirit of the present invention. In addition, the present invention will be described in more detail below using examples, but the present invention is not limited to the following examples. [Example]

[0117] (1) Optical structure of the zoom lens FIG. 1 shows a cross-sectional view of a zoom lens according to a first embodiment of the present invention at the wide-angle end when focusing on infinity. In FIG. 1, "S" indicates an aperture stop. "IP" indicates an image plane, specifically the imaging surface of a solid-state imaging device such as a CCD sensor or a CMOS sensor, or the film surface of a silver halide film. Furthermore, a parallel plate with no substantial refractive power, such as a cover glass "CG," is provided on the object side of the image plane "IP." These points are similar to those in the lens cross-sectional views shown in the other embodiments, and therefore will not be described below.

[0118] The zoom lens of Example 1 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear lens group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0119] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves on the optical axis in a convex orbit toward the image side, and the difference in movement between the wide-angle end position and the telephoto end position of the first lens group G1 moves toward the object side. The second lens group G2 moves toward the image side on the optical axis, and the third lens group G3, fourth lens group G4, fifth lens group G5, and sixth lens group G6 move toward the object side on the optical axis. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image side on the optical axis.

[0120] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0121] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface facing the object side and negative refractive power, a lens L5 with a concave surface facing both sides and negative refractive power, a lens L6 with a concave surface facing both sides and negative refractive power, a lens L7 with a convex surface facing both sides and positive refractive power, and a meniscus lens L8 with a concave surface facing the object side and negative refractive power, and has a negative refractive power as a whole. The lenses L6 and L7 are cemented together to form a cemented lens. The meniscus lens L8 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0122] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a meniscus lens L10 with a concave surface on the object side and negative refractive power, a lens L11 with a biconvex surface and positive refractive power, and a biconvex lens L12 with positive refractive power, and has a positive refractive power as a whole. Lens L9 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0123] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and a negative refractive power, and a lens L14 with a convex surface facing both sides and a positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens.

[0124] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15 having positive refractive power and a biconvex lens L16 having negative refractive power, and has negative refractive power as a whole. The lenses L15 and L16 are cemented together to form a cemented lens.

[0125] The sixth lens group G6 is composed of, in order from the object side, a lens L17 with biconvex surfaces and positive refractive power, a meniscus lens L18 with a convex surface on the object side and negative refractive power, and a meniscus lens L19 with a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. Note that the lens L17 and the meniscus lens L19 are glass-molded aspherical lenses with aspherical surfaces on both sides.

[0126] (2) Numerical examples Next, numerical examples using specific numerical values ​​of the zoom lens will be described. Table 1 shows surface data for the zoom lens of Example 1 according to the present invention. Note that surfaces 36 and 37 in Table 1 are surface data for the cover glass CG. In Table 1, "surface number" indicates the order of the lens surface counted from the object side to the image side, "r" indicates the radius of curvature of each lens surface (mm), "d" indicates the lens thickness or air gap (mm) on the optical axis, "Nd" indicates the refractive index at the d-line (wavelength λ=587.56 nm), and "νd" indicates the Abbe number at the d-line. In Table 1, "d (surface number)" in the "d" column indicates that the spacing on the optical axis of the lens surface is a variable spacing that changes during magnification or focusing. Note that "∞" in the "r" column indicates infinity, meaning that the surface is flat. The sign of the radius of curvature is positive when the surface is convex toward the object side. Furthermore, a surface with "ASPH" next to the surface number indicates that the surface is an aspherical surface, and "STOP" indicates that the surface is an aperture stop.

[0127] Table 2 shows the specifications of this zoom lens. "f" is the focal length (mm), "FNo." is the F-number, "ω" is the half angle of view (°), and "Y" is the image height (mm). From the left, the values ​​are listed at the wide-angle end, the mid-focal length position, and the telephoto end.

[0128] Table 3 shows the variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 3 shows the values ​​at the wide-angle end, mid-focal length position, and telephoto end. In Table 3, "d (surface number)" in the spacing column indicates the spacing between the lens surfaces indicated by the surface number. All lengths in Table 3 are in millimeters.

[0129] Table 4 shows the aspherical coefficients of each aspherical surface. The aspherical coefficients are the numerical values ​​when each aspherical shape is defined by the following formula (20). In Table 4, "E-xx" means "×10 -xx " means.

[0130] x(H)=(H 2 / r) / [1+{1-(1+k)·(H / r) 2} 1 / 2 ]+A4H 4 +A6H 6 +A8H 8 +A 10 H 10 +A 12 H 12 ···(20) however, H: Coordinate perpendicular to the optical axis, with the surface vertex as the origin x(H): Displacement in the optical axis direction at H r: paraxial radius of curvature k: conic constant A4: 4th order aspheric coefficients A6: 6th order aspheric coefficients A8: 8th order aspheric coefficient A 10 :10th order aspheric coefficients A 12 :12th order aspheric coefficients

[0131] The group focal length of each lens group is shown in Table 5. Note that all lengths in Table 5 are in millimeters.

[0132] Table 36 shows the values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of the parameters used to find the values ​​of each conditional expression.

[0133] The matters relating to the above-mentioned tables are the same as those for the tables shown in the other embodiments, and therefore, the explanation will be omitted below.

[0134] [Table 1] Surface number rd Nd νd Object plane ∞ d(0) 1 228.1173 1.7000 1.80517 25.46 2 93.2711 10.2177 1.49700 81.61 3 -657.1718 0.2000 4 68.6775 7.1742 1.83480 42.72 5 166.4812 d(5) 6 154.1064 1.4000 1.83480 42.72 7 24.1848 8.9247 8 -103.3029 1.2000 1.51680 64.20 9 111.5476 2.7023 10 -110.7755 1.2000 1.59282 68.62 11 34.4258 11.5628 1.83400 37.34 12 -52.9245 5.2085 13ASPH -29.4114 1.5000 1.59201 67.02 14ASPH -61.5331 d(14) 15STOP ∞ 1.0000 16ASPH 78.4957 4.3414 1.77376 47.17 17ASPH -117.1964 1.1618 18 -84.6002 1.1000 1.85450 25.15 19 237.6136 0.4000 20 55.9835 10.0729 1.43700 95.10 21 -41.6294 0.1500 22 108.4971 3.4266 1.94593 17.98 23 -1229.3449 d(23) 24 96.5786 1.2000 1.85450 25.15 25 26.2376 9.8998 1.49700 81.61 26 -56.6344 d(26) 27 134.8086 2.2143 1.92285 20.88 28 -238.0793 0.8000 1.80419 46.50 29 28.6272 d(29) 30ASPH 31.9215 9.4819 1.69350 53.18 31ASPH -126.9059 0.1500 32 9031.6795 1.0000 1.75210 25.05 33 65.2851 7.6975 34ASPH -47.9751 1.8000 1.85108 40.12 35ASPH -114.6421 d(35) 36 ∞ 2.5000 1.51680 64.20 37∞1.0000 Image plane ∞

[0135] [Table 2] Wide-angle end Mid-range Telephoto end f 28.8500 50.0005 67.9000 FNo. 2.0625 2.0617 2.0616 ω 37.4696 22.5389 16.8811 Y 21.6330 21.6330 21.6330

[0136] [Table 3] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 162.0000 248.3903 268.2840 d( 5) 1.0967 17.1299 33.3404 1.0967 17.1299 33.3404 d(14) 28.6608 7.3879 1.1000 28.6608 7.3879 1.1000 d(23) 3.1749 1.8264 0.9000 3.1749 1.8264 0.9000 d(26) 2.2000 3.2625 3.8951 4.9320 7.5479 10.6182 d(29) 7.0222 8.1561 9.4231 4.2902 3.8706 2.7000 d(35) 13.4591 20.8444 20.6712 13.4591 20.8442 20.6711

[0137] [Table 4] Face number k A4A6A8A 10 13 0.00000E+00 3.15695E-06 4.48987E-09 -1.96154E-12 5.40304E-16 14 0.00000E+00 4.82176E-07 2.77322E-09 -9.84282E-12 9.47662E-15 16 -3.84803E-01 -7.84836E-07 -5.63055E-10 -1.05178E-11 1.02479E-14 17 0.00000E+00 5.83127E-06 1.11017E-09 -9.65591E-12 1.37587E-14 30 0.00000E+00 1.63932E-06 8.95605E-09 7.30386E-12 -2.11913E-14 31 0.00000E+00 -1.17994E-05 1.25277E-08 -3.62568E-11 8.28915E-14 34 0.00000E+00 -1.19714E-04 3.19957E-07 2.05792E-11 -4.78397E-13 35 0.00000E+00 -9.59467E-05 3.91917E-07 -4.73389E-10 3.28954E-13 Side number A 12 13 0.00000E+00 14 0.00000E+00 16 0.00000E+00 17 0.00000E+00 30 0.00000E+00 31 0.00000E+00 34 0.00000E+00 35 0.00000E+00

[0138] [Table 5] Group number Group focal length G1 119.7623 G2 -33.2595 G3 35.5852 G4 232.6564 G5 -48.9261 G6 109.4687

[0139] 2A shows longitudinal aberration diagrams of Example 1 at the wide-angle end, at the intermediate focal position, and at the telephoto end when focusing on an object at infinity. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0140] In the spherical aberration diagram, the vertical axis shows the ratio to the maximum F-number, and the horizontal axis shows defocus. "FNo." shows the maximum F-number. The solid line d shows the spherical aberration at the d-line (wavelength 587.56 nm), and the dashed line g shows the spherical aberration at the g-line (wavelength 435.84 nm).

[0141] In the astigmatism diagram, the vertical axis represents image height and the horizontal axis represents defocus. "ω" represents the half angle of view (°). The astigmatism values ​​shown are for the d-line, with the solid line ds representing the sagittal image plane for the d-line and the dashed line dm representing the meridional image plane for the d-line.

[0142] In the distortion diagram, the vertical axis represents image height, and the horizontal axis represents distortion (%). "ω" represents the half angle of view (°). The distortion value shown is for the d-line.

[0143] The matters relating to these longitudinal aberration diagrams are the same as those in the longitudinal aberration diagrams shown in other embodiments, and therefore, the explanation thereof will be omitted below. [Example]

[0144] (1) Optical structure of the zoom lens Figure 3 shows a cross-sectional view of a zoom lens according to Example 2 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 2 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear lens group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0145] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves on the optical axis in a convex orbit toward the image side, and the first lens group G1 moves toward the object side by the difference in movement between its wide-angle end position and its telephoto end position. The second lens group G2 moves on the optical axis in a convex orbit toward the image side, and the second lens group G2 moves toward the image side by the difference in movement between its wide-angle end position and its telephoto end position. The third lens group G3, fourth lens group G4, and fifth lens group G5 move toward the object side on the optical axis. The position of the sixth lens group G6 is fixed. When focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image side on the optical axis.

[0146] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0147] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface on the object side and negative refractive power, a lens L5 with a concave surface on both sides and negative refractive power, a meniscus lens L6 with a convex surface on the object side and positive refractive power, a lens L7 with a convex surface on both sides and positive refractive power, and a meniscus lens L8 with a concave surface on the object side and negative refractive power, and has a negative refractive power as a whole. The lens L5 and the meniscus lens L6 are cemented together to form a cemented lens. The meniscus lens L4 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0148] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a lens L10 with a biconvex surface and positive refractive power, a lens L11 with a biconvex surface and negative refractive power, and a meniscus lens L12 with a convex surface on the object side and positive refractive power, and has a positive refractive power as a whole. The lens L11 and the meniscus lens L12 are cemented together to form a cemented lens. The lens L10 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0149] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and negative refractive power, a lens L14 with a convex surface facing both sides and positive refractive power, and a lens L15 with a convex surface facing both sides and positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens. The lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0150] The fifth lens group G5 is composed of a meniscus lens L16 having a convex surface on the object side and negative refractive power.

[0151] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L17 having positive refractive power, a biconvex lens L18 having negative refractive power, and a meniscus lens L19 having a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. The meniscus lens L19 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0152] (2) Numerical examples Next, numerical examples using specific numerical values ​​of the zoom lens will be described. Table 6 shows surface data of the zoom lens of Example 2 according to the present invention. Note that surfaces 37 and 38 in Table 6 are surface data of the cover glass CG. Table 7 shows the specifications of the zoom lens. Table 8 shows the variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 9 shows the aspherical coefficients of each aspherical surface. Table 10 shows the group focal length of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0153] 4A, 4B, and 4C are longitudinal aberration diagrams of Example 2 when focused on an object at infinity at the wide-angle end, the intermediate focal position, and the telephoto end, respectively. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0154] [Table 6] Surface number rd Nd νd Object plane ∞ d(0) 1 488.3117 1.9000 1.92286 20.88 2 266.4935 6.0470 1.49700 81.61 3 -795.1973 0.2000 4 85.3383 8.2586 1.59349 67.00 5 457.1758 d(5) 6ASPH 470.9782 2.3000 1.69350 53.18 7ASPH 23.3736 9.9422 8 -61.8294 1.2000 1.59282 68.62 9 23.8327 7.3224 1.74320 49.34 10 469.3882 0.2000 11 127.0096 3.4111 1.95375 32.32 12 -188.0644 3.0466 13 -36.2096 1.2000 1.60311 60.64 14 -94.4666 d(14) 15STOP ∞ 1.5000 16 49.8244 5.3740 1.92286 20.88 17 -312.5103 0.2000 18 0.0000 0.0000 19ASPH 83.7759 4.0000 1.76802 49.24 20ASPH -157.9637 0.6500 21 -92.6072 1.1000 1.85451 25.15 22 32.3252 5.6361 1.43700 95.10 23 287.8789 d(23) 24 87.1894 1.1000 1.85883 30.00 25 32.2086 8.7420 1.43700 95.10 26 -100.3934 0.5582 27ASPH 40.2417 10.3757 1.59201 67.02 28ASPH -34.9304 d(28) 29 89.2405 0.9000 1.91082 35.25 30 27.3942 d(30) 31 69.5031 10.0000 1.95375 32.32 32 -57.1932 0.2000 33 -175.9742 0.9000 1.78590 43.93 34 66.3316 6.0359 35ASPH -50.5751 1.3500 1.69350 53.18 36ASPH -630.4649 d(36) 37 ∞ 2.5000 1.51680 64.20 38∞1.0000 Image plane ∞

[0155] [Table 7] Wide-angle end Mid-range Telephoto end f 28.8446 50.0050 63.1102 FNo. 2.0603 2.0602 2.0601 ω 38.2986 22.7291 18.0779 Y 21.6330 21.6330 21.6330

[0156] [Table 8] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 132.6013 221.0513 206.6780 d( 5) 1.4000 18.8861 33.9178 1.4000 18.8861 33.9178 d(14) 28.3482 4.6620 1.4000 28.3482 4.6620 1.4000 d(23) 3.1809 1.9130 1.3000 3.1809 1.9130 1.3000 d(28) 1.2461 4.6613 4.4105 3.2669 7.9724 9.1075 d(30) 9.0850 14.6878 18.1551 7.0642 11.3767 13.4581 d(36) 16.9888 16.9888 16.9888 16.9888 16.9888 16.9888

[0157] [Table 9] Face number k A4A6A8A 10 6 0.00000E+00 4.25380E-06 -6.85256E-09 1.26033E-11 -1.27156E-14 7 0.00000E+00 1.98055E-06 -4.41007E-09 2.50465E-11 -7.99086E-14 19 0.00000E+00 -1.07245E-05 -4.01788E-10 3.95441E-12 -4.29624E-14 20 0.00000E+00 -9.19409E-06 1.67455E-08 -1.46949E-11 -2.74318E-14 27 -1.26311E+00 -6.46252E-06 3.49289E-09 3.68793E-12 -2.84521E-14 28 -4.99713E-01 1.35862E-06 -6.51669E-09 1.05664E-11 -3.08812E-14 35 6.22066E+00 -4.86835E-05 3.01925E-07 -1.07434E-09 2.23970E-12 36 0.00000E+00 -5.00063E-05 2.82284E-07 -1.05862E-09 2.23943E-12 Face number A 12 6 6.00773E-18 7 1.96207E-16 19 1.30816E-16 20 1.40638E-16 27 3.50092E-17 28 2.79662E-17 35 -1.58635E-15 36 -2.02602E-15

[0158] [Table 10] Group number Group focal length G1 151.3125 G2 -31.6585 G3 69.6855 G4 31.7236 G5 -43.7015 G6 256.5897 [Example]

[0159] (1) Optical structure of the zoom lens Figure 5 shows a cross-sectional view of a zoom lens according to Example 3 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 3 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having negative refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear lens group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0160] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object along the optical axis, and the second lens group G2 moves toward the image along the optical axis. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 move toward the object along the optical axis. The sixth lens group G6 moves along the optical axis in a convex trajectory toward the object, and the difference in movement of the sixth lens group G6 between its position at the wide-angle end and its position at the telephoto end is its movement toward the object. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image along the optical axis.

[0161] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0162] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface facing the object side and negative refractive power, a lens L5 with a concave surface facing both sides and negative refractive power, a lens L6 with a concave surface facing both sides and negative refractive power, a lens L7 with a convex surface facing both sides and positive refractive power, and a meniscus lens L8 with a concave surface facing the object side and negative refractive power, and has a negative refractive power as a whole. The lenses L6 and L7 are cemented together to form a cemented lens. The lens L5 and the meniscus lens L8 are glass-molded aspherical lenses with aspherical surfaces on both sides.

[0163] The third lens group G3 is composed of, in order from the object side, a meniscus lens L9 with a convex surface facing the object side and positive refractive power, a meniscus lens L10 with a convex surface facing the object side and negative refractive power, a lens L11 with convex surfaces on both sides and positive refractive power, and a lens L12 with concave surfaces on both sides and negative refractive power, and has positive refractive power as a whole. The meniscus lens L10 and the lens L11 are cemented together to form a cemented lens.

[0164] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and negative refractive power, a lens L14 with a convex surface facing both sides and positive refractive power, and a lens L15 with a convex surface facing both sides and positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens. The lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0165] The fifth lens group G5 is composed of a meniscus lens L16 having a convex surface on the object side and negative refractive power.

[0166] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L17 having positive refractive power, a biconvex lens L18 having negative refractive power, and a meniscus lens L19 having a concave surface on the object side and negative refractive power, and has a negative refractive power as a whole. Lens L18 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0167] (2) Numerical examples Next, numerical examples using specific numerical values ​​of the zoom lens will be described. Table 11 shows surface data of the zoom lens of Example 3 according to the present invention. Note that surfaces 36 and 37 in Table 11 are surface data of the cover glass CG. Table 12 shows the specifications of the zoom lens. Table 13 shows variable spacings on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 14 shows the aspherical coefficients of each aspherical surface. Table 15 shows the group focal lengths of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0168] 6A, 6B, and 6C are longitudinal aberration diagrams of Example 3 when focused on an object at infinity at the wide-angle end, the intermediate focal position, and the telephoto end, respectively. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0169] [Table 11] Surface number rd Nd νd Object plane ∞ d(0) 1 1075.3000 1.7000 1.84666 23.78 2 201.0083 7.1436 1.497 81.61 3 -270.8627 0.2000 4 60.3453 7.5607 1.72916 54.67 5 163.7758 d(5) 6 93.4647 1.5000 1.72916 54.67 7 20.8297 9.5477 8ASPH -128.8253 1.5000 1.51633 64.06 9ASPH 171.029 3.9661 10 -47.5498 1.200 1.497 81.61 11 66.6201 7.537 1.60342 38.01 12 -31.7995 2.2294 13ASPH -20.4248 1.5000 1.59201 67.02 14ASPH -32.0348 d(14) 15STOP ∞ 1.0000 16 36.9364 5.8711 1.92286 20.88 17 162.3623 0.5000 18 52.4558 1.2000 1.90366 31.31 19 20.5298 10.3434 1.59319 20 -1044.2297 3.0097 21 -44.5967 1.0000 1.92286 20.88 22 170.2708 d(22) 23 33.7074 1.0000 1.8707 40.73 24 20.2979 13.7526 1.59282 68.62 25 -66.2206 0.1500 26ASPH 37.0038 7.1362 1.59201 67.02 27ASPH -69.8996 d(27) 28 65. 29 25.8946 d(29) 30 70.3865 6.1131 1.80518 25.46 31 -48.8619 0.1500 32ASPH -68.9464 1.5000 1.77377 47.17 33ASPH 116.0005 8.1904 34 -19.7407 1.2000 1.83481 42.72 35 -31.9546 d(35) 36 ∞ 2.5000 1.5168 64.2 37 ∞ 1.0000

[0170] [[ID=]] [Table 12] Wide-angle end Mid-range Telephoto end f 28.8261 54.9943 67.8999 FNo. 2.0600 2.0600 2.0600 ω 37.7052 20.7096 16.8759 Y 21.6330 21.6330 21.6330

[0171] [Table 13] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 132.0000 245.6228 272.2880 d( 5) 1.0000 21.7798 29.7604 1.0000 21.7798 29.7604 d(14) 30.7031 8.1523 1.1000 30.7031 8.1523 1.1000 d(22) 0.8000 1.0607 1.7035 0.8000 1.0607 1.7035 d(27) 2.2000 3.1636 3.7258 4.6211 6.8141 8.5663 d(29) 7.9418 8.8393 11.7252 5.5723 5.3687 6.9428 d(35) 13.2540 19.2803 17.5961 13.2024 19.1005 17.538

[0172] [Table 14] Face number k A4A6A8A 10 8 0.00000E+00 5.99256E-06 -9.92313E-09 -2.03799E-11 7.95767E-14 9 0.00000E+00 7.45800E-06 2.20267E-09 -2.70090E-11 1.50383E-13 13 0.00000E+00 3.31362E-05 -7.59297E-08 2.16614E-10 -1.87828E-13 14 0.00000E+00 2.25539E-05 -9.37045E-08 2.03224E-10 -2.85120E-13 26 0.00000E+00 -1.04183E-05 -6.26305E-09 -4.25261E-11 5.46919E-14 27 8.48595E+00 3.75598E-06 -4.82573E-09 -5.48703E-11 1.60465E-13 32 0.00000E+00 -8.77504E-06 8.74509E-08 -1.19421E-10 -3.28542E-13 33 0.00000E+00 -1.41405E-05 5.95408E-08 4.68307E-11 -1.16573E-12 Face number A 12 8 0.00000E+00 9 0.00000E+00 13 0.00000E+00 14 0.00000E+00 26 -9.18068E-17 27 -2.97021E-16 32 1.64283E-15 33 2.98855E-15

[0173] [Table 15] Group number Group focal length G1 113.5972 G2 -30.0422 G3 214.7625 G4 24.7785 G5 -52.0308 G6 -312.8100 [Example]

[0174] (1) Optical structure of the zoom lens Figure 7 shows a cross-sectional view of a zoom lens according to Example 4 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 4 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0175] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side on the optical axis. The second lens group G2 moves along the optical axis in a trajectory convex toward the image side, and the second lens group G2 moves toward the image side by the difference in movement between its wide-angle end position and its telephoto end position. The third lens group G3, fourth lens group G4, fifth lens group G5, and sixth lens group G6 move toward the object side on the optical axis. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image side on the optical axis.

[0176] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0177] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface facing the object side and negative refractive power, a lens L5 with a concave surface facing both sides and negative refractive power, a lens L6 with a concave surface facing both sides and negative refractive power, a lens L7 with a convex surface facing both sides and positive refractive power, and a meniscus lens L8 with a concave surface facing the object side and negative refractive power, and has a negative refractive power as a whole. The lenses L6 and L7 are cemented together to form a cemented lens. The meniscus lens L8 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0178] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a lens L10 with a biconvex surface and positive refractive power, a lens L11 with a biconvex surface and negative refractive power, and a meniscus lens L12 with a convex surface facing the object side and positive refractive power, and has a positive refractive power as a whole. The lens L11 and the meniscus lens L12 are cemented together to form a cemented lens. The lens L10 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0179] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and negative refractive power, a lens L14 with a convex surface facing both sides and positive refractive power, and a lens L15 with a convex surface facing both sides and positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens. The lens L15 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0180] The fifth lens group G5 is composed of a meniscus lens L16 having a convex surface on the object side and negative refractive power.

[0181] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L17 having positive refractive power, a biconvex lens L18 having negative refractive power, and a meniscus lens L19 having a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. The meniscus lens L19 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0182] (2) Numerical examples Next, numerical examples using specific numerical values ​​of the zoom lens will be described. Table 16 shows surface data of the zoom lens of Example 4 according to the present invention. Note that surfaces 37 and 38 in Table 16 are surface data of the cover glass CG. Table 17 shows the specifications of the zoom lens. Table 18 shows variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 19 shows the aspherical coefficients of each aspherical surface. Table 20 shows the group focal length of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0183] 8 shows longitudinal aberration diagrams of Example 4 when focused on an object at infinity at (A) the wide-angle end, (B) the intermediate focal position, and (C) the telephoto end. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0184] [Table 16] Surface number rd Nd νd Object plane ∞ d(0) 1 584.9510 1.9000 1.92286 20.88 2 335.1390 ​​5.8518 1.49700 81.61 3 -484.5185 0.2000 4 73.8690 8.4979 1.59349 67.00 5 333.7144 d(5) 6 191.9033 1.3429 1.83481 42.72 7 23.7672 8.3472 8 -198.4650 1.2000 1.55032 75.50 9 108.8512 1.6970 10 -314.1456 1.2000 1.57598 45.49 11 27.5484 12.9492 1.85068 35.54 12 -67.5872 2.1077 13ASPH -36.6881 1.5000 1.59201 67.02 14ASPH -240.2023 d(14) 15STOP ∞ 1.5000 16 51.7372 5.0735 1.92286 20.88 17 -456.7554 0.2000 18 ∞ 0.0000 19ASPH 52.7546 4.0000 1.76802 49.24 20ASPH 1259.6472 0.6500 21 -251.2508 1.1000 1.85451 25.15 22 28.3485 6.0872 1.43700 95.10 23 301.3940 d(23) 24 204.5153 1.1000 1.85883 30.00 25 34.5615 7.5463 1.43700 95.10 26 -87.2684 0.2000 27ASPH 39.0112 9.9222 1.59201 67.02 28ASPH -34.6335 d(28) 29 97.5670 0.9000 1.91082 35.25 30 28.1544 d(30) 31 63.3145 10.0000 1.95375 32.32 32 -54.5726 0.2000 33 -162.2331 0.9000 1.78590 43.93 34 66.5808 6.2203 35ASPH -45.0592 1.3500 1.69350 53.18 36ASPH -670.5905 d(36) 37 ∞ 2.5000 1.51680 64.20 38 ∞ 1.0000

[0185] [Table 17] Wide-angle end Mid-range Telephoto end f 28.6589 49.9998 63.1068 FNo. 2.0600 2.0600 2.0600 ω 38.4812 22.7291 18.1163 Y 21.6330 21.6330 21.6330

[0186] [Table 18] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 225.0000 223.4500 211.7202 d( 5) 1.4000 17.4028 29.8005 1.4000 17.4028 29.8005 d(14) 27.8963 5.0232 1.4000 27.8963 5.0232 1.4000 d(23) 3.3269 1.9266 1.3000 3.3269 1.9266 1.3000 d(28) 1.2500 3.2269 2.7926 2.6272 6.5481 7.5083 d(30) 8.4616 13.9029 17.8075 7.0845 10.5816 13.0917 d(36) 15.4220 17.8245 17.9360 15.4220 17.8245 17.9360

[0187] [Table 19] Face number k A4A6A8A 10 13 0.00000E+00 2.53932E-06 -9.85497E-10 -2.98625E-12 6.99946E-14 14 0.00000E+00 2.99038E-07 -1.39742E-09 -1.94021E-13 4.55858E-14 19 0.00000E+00 -6.05319E-06 -1.55431E-10 -2.72886E-12 -4.35747E-15 20 0.00000E+00 -3.55070E-06 1.25268E-08 -1.14127E-11 -4.66870E-15 27 -1.09082E+00 -6.31875E-06 2.11979E-09 6.65872E-12 -4.21755E-14 28 -4.97503E-01 1.08173E-06 -7.53168E-09 1.02970E-11 -3.58136E-14 35 4.89146E+00 -4.09778E-05 2.59611E-07 -9.56304E-10 2.00179E-12 36 0.00000E+00 -4.21039E-05 2.36369E-07 -9.25601E-10 1.99424E-12 Face number A 12 13 -1.39393E-16 14 -8.34643E-17 19 -4.42653E-17 20 -9.15748E-18 27 5.24034E-17 28 3.29530E-17 35 -1.26366E-15 36 -1.83317E-15

[0188] [Table 20] Group number Group focal length G1 130.5918 G2 -32.0368 G3 59.6182 G4 34.0119 G5 -43.7189 G6 219.3511 [Example]

[0189] (1) Optical structure of the zoom lens 9 shows a cross-sectional view of a zoom lens according to a fifth embodiment of the present invention at the wide-angle end when focusing at infinity. The zoom lens of the fifth embodiment is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear lens group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0190] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object along the optical axis. The second lens group G2 moves toward the image along the optical axis. The third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 move toward the object along the optical axis. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image along the optical axis.

[0191] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0192] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface facing the object side and negative refractive power, a lens L5 with a concave surface facing both sides and negative refractive power, a lens L6 with a concave surface facing both sides and negative refractive power, a lens L7 with a convex surface facing both sides and positive refractive power, and a meniscus lens L8 with a concave surface facing the object side and negative refractive power, and has a negative refractive power as a whole. The lenses L6 and L7 are cemented together to form a cemented lens. The meniscus lens L8 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0193] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a meniscus lens L10 with a concave surface on the object side and negative refractive power, a lens L11 with a biconvex surface and positive refractive power, and a biconvex lens L12 with positive refractive power, and has a positive refractive power as a whole. Lens L9 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0194] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and a negative refractive power, and a lens L14 with a convex surface facing both sides and a positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens.

[0195] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15 having positive refractive power and a biconvex lens L16 having negative refractive power, and has negative refractive power as a whole. The lenses L15 and L16 are cemented together to form a cemented lens.

[0196] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L17 having positive refractive power, a biconvex lens L18 having negative refractive power, and a meniscus lens L19 having a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. Note that the lens L17 and the meniscus lens L19 are glass-molded aspherical lenses with aspherical surfaces on both sides.

[0197] (2) Numerical examples Next, numerical examples to which specific numerical values ​​of the zoom lens are applied will be described. Table 21 shows surface data of the zoom lens of Example 5 according to the present invention. Note that surfaces 36 and 37 in Table 21 are surface data of the cover glass CG. Table 22 shows the specifications of the zoom lens. Table 23 shows the variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 24 shows the aspherical coefficients of each aspherical surface. Table 25 shows the group focal length of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0198] 10 shows longitudinal aberration diagrams of Example 5 when focused on an object at infinity at (A) the wide-angle end, (B) the intermediate focal position, and (C) the telephoto end. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0199] [Table 21] Surface number rd Nd νd Object plane ∞ d(0) 1 242.4366 1.6000 1.80517 25.46 2 88.2738 10.7000 1.49700 81.61 3 -441.4048 0.1500 4 66.1537 7.6000 1.83480 42.72 5 172.8627 d(5) 6 180.4695 1.4000 1.83480 42.72 7 23.6900 8.7339 8 -126.3576 1.2000 1.59282 68.62 9 132.6782 3.4232 10 -67.1094 1.2000 1.48749 70.44 11 39.5592 8.7252 1.72046 34.71 12 -42.1951 5.2498 13ASPH -25.1443 1.4000 1.59201 67.02 14ASPH -43.8192 d(14) 15STOP ∞ 1.0000 16ASPH 75.7572 6.2420 1.77376 47.17 17ASPH -58.4256 0.4000 18 -60.2201 1.0000 1.77046 29.74 19 87.8853 1.4106 20 52.2529 10.6328 1.43700 95.10 21 -41.7964 0.1500 22 108.0339 4.4047 1.86965 20.02 23 -514.9408 d(23) 24 81.4900 1.0000 1.80517 25.46 25 24.7328 10.0484 1.49700 81.61 26 -65.4521 d(26) 27 111.4756 2.2988 1.94593 17.98 28 -314.1050 0.8000 1.80419 46.50 29 26.5730 d(29) 30ASPH 32.2561 9.7541 当页有图 有图 31ASPH -66.当页有图 有图 32 -158.9323 1.0002 1.92118 23.96 33 74.9959 6.7926 当页有图 有图 34ASPH -51.6900 2.4616 1.85108 40.12 35ASPH -114.6317 d(35) 36 ∞ 2.5000 1.51680 64.20 37 ∞ 1.0000

[0200] [Table 22] 当页有图 说明:原内容中部分“d(xx)”等可能是特定领域的特定标识或变量,保留原样未翻译;对于一些不太明确含义的“当页有图”“有图”等表述,根据规则保留原文形式以尽量准确呈现原文内容。你可根据实际情况进一步确认和调整。 Wide-angle end, middle viewing end f 28.8327 49.9995 67.8968 FNo. 2.0550 2.0550 2.0550 ω 37.3095 22.5533 16.8761 Y 21.6330 21.6330 21.6330

[0201] [Table 23] Wide-angle end, center telephoto end. d(0) ∞ ∞ ∞ 162.5000 237.9451 268.2284 d(5) 1.2710 16.4926 31.5587 1.2710 16.4926 31.5587 d(14) 26.3469 6.8986 1.1000 26.3469 6.8986 1.1000 d(23) 3.5143 1.8915 0.9000 3.5143 1.8915 0.9000 d(26) 2.1965 3.0826 3.5014 4.8252 7.1826 9.6874 d(29) 6.4433 8.3799 9.4106 3.8145 4.2798 3.2246 d(35) 13.3000 20.8818 20.8729 13.3000 20.8818 20.8729

[0202] [Table 24] Face number k A4A6A8A 10 13 0.00000E+00 5.81442E-06 4.50876E-10 2.18865E-11 -2.13772E-14 14 0.00000E+00 2.00369E-06 -4.08259E-09 1.05654E-11 -2.00616E-14 16 -2.96292E+00 -2.79004E-06 -4.13468E-09 -4.16288E-12 -2.18632E-14 17 0.00000E+00 3.34380E-06 -4.30411E-09 -1.40041E-12 -1.81366E-14 30 0.00000E+00 2.10735E-06 1.14637E-08 -4.71573E-12 7.00616E-15 31 0.00000E+00 -1.08404E-05 3.70694E-08 -8.05122E-11 1.01716E-13 34 0.00000E+00 -9.90441E-05 2.64232E-07 -5.78065E-11 -1.89168E-13 35 0.00000E+00 -7.61167E-05 2.90586E-07 -3.78441E-10 3.84404E-13 Face number A 12 13 0.00000E+00 14 0.00000E+00 16 0.00000E+00 17 0.00000E+00 30 0.00000E+00 31 0.00000E+00 34 0.00000E+00 35 0.00000E+00

[0203] [Table 25] Group number Group focal length G1 110.9863 G2 -31.2074 G3 36.0197 G4 193.4895 G5 -47.8285 G6 122.4298 [Example]

[0204] (1) Optical structure of the zoom lens Figure 11 shows a cross-sectional view of a zoom lens according to Example 6 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 6 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0205] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves on the optical axis in a convex orbit toward the image side, and the difference in movement between the wide-angle end position and the telephoto end position of the first lens group G1 moves toward the object side. The second lens group G2 moves toward the image side on the optical axis. The third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 move toward the object side on the optical axis. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image side on the optical axis.

[0206] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0207] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface facing the object side and negative refractive power, a lens L5 with a concave surface facing both sides and negative refractive power, a lens L6 with a concave surface facing both sides and negative refractive power, a lens L7 with a convex surface facing both sides and positive refractive power, and a meniscus lens L8 with a concave surface facing the object side and negative refractive power, and has a negative refractive power as a whole. The lenses L6 and L7 are cemented together to form a cemented lens. The meniscus lens L8 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0208] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a biconcave lens L10 with a negative refractive power, a biconvex lens L11 with a positive refractive power, and a meniscus lens L12 with a convex surface facing the object side and positive refractive power, and has a positive refractive power as a whole. Lens L9 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0209] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L13 with a convex surface facing the object side and a negative refractive power, and a lens L14 with a convex surface facing both sides and a positive refractive power, and has a positive refractive power as a whole. The meniscus lens L13 and the lens L14 are cemented together to form a cemented lens.

[0210] The fifth lens group G5 is composed of, in order from the object side, a biconvex lens L15 having positive refractive power and a biconvex lens L16 having negative refractive power, and has negative refractive power as a whole. The lenses L15 and L16 are cemented together to form a cemented lens.

[0211] The sixth lens group G6 is composed of, in order from the object side, a meniscus lens L17 with a convex surface on the object side and negative refractive power, a lens L18 with a convex surface on both sides and positive refractive power, and a meniscus lens L19 with a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. Note that lens L18 and meniscus lens L19 are glass-molded aspherical lenses with aspherical surfaces on both sides.

[0212] (2) Numerical examples Next, numerical examples to which specific numerical values ​​of the zoom lens are applied will be described. Table 26 shows surface data of the zoom lens of Example 6 according to the present invention. Note that surfaces 36 and 37 in Table 26 are surface data of the cover glass CG. Table 27 shows the specifications of the zoom lens. Table 28 shows the variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 29 shows the aspherical coefficients of each aspherical surface. Table 30 shows the group focal length of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0213] 12 shows longitudinal aberration diagrams of Example 6 when focused on an object at infinity at (A) the wide-angle end, (B) the intermediate focal position, and (C) the telephoto end. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0214] [Table 26] Surface number rd Nd νd Object plane ∞ d(0) 1 263.8315 1.7000 1.80517 25.46 2 98.8472 10.5907 1.49700 81.61 3 -378.8893 0.2000 4 66.1089 6.8015 1.83480 42.72 5 143.7683 d(5) 6 145.4298 1.4000 1.83480 42.72 7 23.7438 8.8495 8 -102.1648 1.2000 1.48749 70.44 9 132.5132 3.1525 10 -68.7906 1.2000 1.59349 67.00 11 37.8839 10.0000 1.83400 37.34 12 -50.8286 6.1749 13ASPH -27.3317 1.5000 1.59201 67.02 14ASPH -44.1903 d(14) 15STOP ∞ 1.0000 16ASPH 83.5638 4.2254 1.77376 47.17 17ASPH -129.7307 0.9676 18 -102.4360 1.1000 1.85450 25.15 19 150.9564 0.1500 20 55.1028 10.4532 1.43700 95.10 21 -42.0419 0.1500 22 63.1575 4.0687 1.94593 17.98 23 240.8602 d(23) 24 67.2387 1.2000 1.92118 23.96 25 24.3696 10.4603 1.49700 81.61 26 -54.2280 d(26) ​​​​​​​​​​​​​​​​​​​​​​​​​ Wide-angle end Mid-range Telephoto end f 28.8514 50.0014 67.9005 FNo. 2.0627 2.0617 2.0617 ω 37.2010 22.6008 16.8802 Y 21.6330 21.6330 21.6330

[0216] [Table 28] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 162.0000 249.6118 268.9386 d( 5) 1.2612 16.4996 33.4421 1.2612 16.4996 33.4421 d(14) 29.5051 7.4749 1.1000 29.5051 7.4749 1.1000 d(23) 2.8140 1.5743 0.9000 2.8140 1.5743 0.9000 d(26) 2.1984 2.7900 3.2245 4.5272 6.2374 8.6653 d(29) 6.9512 9.2477 10.1399 4.6224 5.8002 4.6991 d(35) 14.2408 21.7724 21.2255 14.2408 21.7724 21.2255

[0217] [Table 29] Face number k A4A6A8A 10 13 0.00000E+00 2.36219E-06 9.70073E-09 -1.23243E-11 1.47582E-14 14 0.00000E+00 -2.10795E-07 6.03625E-09 -1.71047E-11 1.41918E-14 16 -9.67256E-01 -1.09848E-06 -2.42927E-10 -8.55891E-12 3.25859E-15 17 0.00000E+00 5.05900E-06 1.38265E-09 -8.28990E-12 6.84892E-15 32 0.00000E+00 5.96933E-07 4.11247E-09 3.16026E-11 -7.61914E-14 33 0.00000E+00 -1.84883E-05 -2.29522E-09 -3.71528E-11 1.51955E-13 34 0.00000E+00 -1.40104E-04 4.03188E-07 -2.60621E-10 -8.46639E-14 35 0.00000E+00 -1.13974E-04 4.93938E-07 -8.23618E-10 7.52769E-13 Face number A 12 13 0.00000E+00 14 0.00000E+00 16 0.00000E+00 17 0.00000E+00 32 0.00000E+00 33 0.00000E+00 34 0.00000E+00 35 0.00000E+00

[0218] [Table 20] Group number Group focal length G1 119.7302 G2 -34.0910 G3 34.9827 G4 173.6994 G5 -46.2681 G6 159.3853 [Example]

[0219] (1) Optical structure of the zoom lens Figure 13 shows a cross-sectional view of a zoom lens according to Example 7 of the present invention at the wide-angle end when focusing at infinity. The zoom lens of Example 7 is composed of, 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, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The fifth lens group G5 and the sixth lens group G6 correspond to the rear group GN. An aperture stop S is located adjacent to the object side of the third lens group G3.

[0220] When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves on the optical axis in a convex orbit toward the image side, and the difference in movement between the wide-angle end position and the telephoto end position of the first lens group G1 moves toward the object side. The second lens group G2 moves toward the image side on the optical axis. The third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 move toward the object side on the optical axis. Furthermore, when focusing from an object at infinity to an object at a finite distance, the fifth lens group G5 moves toward the image side on the optical axis.

[0221] The configuration of each lens group will be explained below. The first lens group G1 is composed of, in order from the object side, a meniscus lens L1 with a convex surface on the object side and negative refractive power, a lens L2 with convex surfaces on both sides and positive refractive power, and a meniscus lens L3 with a convex surface on the object side and positive refractive power, and has positive refractive power as a whole. The meniscus lens L1 and lens L2 are cemented together to form a cemented lens.

[0222] The second lens group G2 is composed of, in order from the object side, a meniscus lens L4 with a convex surface on the object side and negative refractive power, a lens L5 with a concave surface on both sides and negative refractive power, a meniscus lens L6 with a convex surface on the object side and positive refractive power, a lens L7 with a convex surface on both sides and positive refractive power, and a meniscus lens L8 with a concave surface on the object side and negative refractive power, and has a negative refractive power as a whole. The lens L5 and the meniscus lens L6 are cemented together to form a cemented lens. The meniscus lens L8 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0223] The third lens group G3 is composed of, in order from the object side, a lens L9 with a biconvex surface and positive refractive power, a lens L10 with a biconvex surface and positive refractive power, a meniscus lens L11 with a biconvex surface and negative refractive power on the object side, a lens L12 with a biconvex surface and positive refractive power on the object side, and a meniscus lens L13 with a concave surface and negative refractive power on the object side, and has a positive refractive power as a whole. The meniscus lens L11 and the lens L12 are cemented together to form a cemented lens. The lens L10 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0224] The fourth lens group G4 is composed of, in order from the object side, a meniscus lens L14 with a concave surface facing the object side and positive refractive power, a meniscus lens L15 with a concave surface facing the object side and negative refractive power, and a lens L16 with a convex surface facing both sides and positive refractive power, and has a positive refractive power as a whole. The meniscus lens L14 and the meniscus lens L15 are cemented together to form a cemented lens. The lens L16 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0225] The fifth lens group G5 is composed of a meniscus lens L17 having a convex surface on the object side and negative refractive power.

[0226] The sixth lens group G6 is composed of, in order from the object side, a biconvex lens L18 having positive refractive power, a biconvex lens L19 having negative refractive power, and a meniscus lens L20 having a concave surface on the object side and negative refractive power, and has a positive refractive power as a whole. The meniscus lens L20 is a glass-molded aspherical lens with aspherical surfaces on both sides.

[0227] (2) Numerical examples Next, numerical examples to which specific numerical values ​​of the zoom lens are applied will be described. Table 31 shows surface data of the zoom lens of Example 7 according to the present invention. Note that surfaces 38 and 39 in Table 31 are surface data of the cover glass CG. Table 32 shows the specifications of the zoom lens. Table 33 shows the variable spacing on the optical axis of the zoom lens when focusing on an object at infinity and when focusing on a close-up object. Table 34 shows the aspherical coefficients of each aspherical surface. Table 35 shows the group focal length of each lens group. Furthermore, Table 36 shows the numerical values ​​of conditional expressions (1) to (19), and Table 37 shows the values ​​of each parameter used to calculate the numerical values ​​of each conditional expression.

[0228] 14 shows longitudinal aberration diagrams of Example 7 when focused on an object at infinity at (A) the wide-angle end, (B) the intermediate focal position, and (C) the telephoto end. From the left, the diagrams show spherical aberration (mm), astigmatism (mm), and distortion (%).

[0229] [Table 31] Surface number rd Nd νd Object plane ∞ d(0) 1 642.8163 1.9800 1.92286 20.88 2 352.6007 5.9768 1.49700 81.61 3 -449.9175 0.2000 4 74.2392 8.2157 1.61800 63.39 5 237.3524 d(5) 6 180.3487 1.0000 1.74320 49.34 7 21.4745 10.2614 8 -80.2941 1.2000 1.59282 68.62 9 35.1160 4.2068 1.74320 49.34 10 148.5417 1.3053 11 952.9344 4.6448 1.93664 34.16 12 -52.5934 2.8828 13ASPH -30.2289 1.2000 1.59201 67.02 14ASPH -63.3257 d(14) 15STOP ∞ 1.2500 16 50.0000 5.2620 1.92286 20.88 17 717.1963 0.2000 18ASPH 102.4244 5.3422 1.86120 41.68 19ASPH -141.2748 0.2000 20 499.5151 1.0000 1.89249 24.28 21 23.3697 10.0088 1.45860 90.19 22 -106.6063 0.6500 23 -86.6993 1.3000 1.89264 32.07 24 -131.4654 d(24) 25 -119.5963 7.7006 1.49700 81.61 26 -24.9411 1.0000 1.91082 35.25 27 -36.6904 0.2000 28ASPH 72.0635 8.2574 1.59201 67.02 29ASPH -40.5253 d(29) 30 78.1173 0.9000 1.91082 35.25 31 27.2141 d(31) 32 48.3458 10.0000 1.78979 32.15 33 -52.9412 0.2000 34 -154.9653 0.9000 1.59209 68.69 35 44.5870 6.8167 36ASPH -46.6595 1.3500 1.85108 40.12 37ASPH -658.1559 d(37) 38 ∞ 2.5000 1.51680 64.20 39∞1.0000

[0230] [Table 32] Wide-angle end Mid-range Telephoto end f 28.8400 49.9998 67.9612 FNo. 2.0600 2.0600 2.0600 ω 37.9724 22.7289 16.9458 Y 21.6330 21.6330 21.6330

[0231] [Table 33] Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end d( 0) ∞ ∞ ∞ 221.9999 221.4499 207.1170 d( 5) 1.4000 16.9922 33.6034 1.4000 16.9922 33.6034 d(14) 31.9017 7.6509 1.4000 31.9017 7.6509 1.4000 d(24) 3.5198 2.1427 1.3191 3.5198 2.1427 1.3191 d(29) 1.2500 1.9056 1.4253 2.7351 5.0665 6.3704 d(31) 7.2918 11.8349 16.3623 5.8067 8.6740 11.4172 d(37) 13.5253 18.9122 19.6614 13.5253 18.9122 19.6614

[0232] [Table 34] Face number k A4A6A8A 10 13 0.00000E+00 8.07438E-06 -2.89005E-08 1.45835E-11 1.78012E-13 14 0.00000E+00 1.80353E-06 -3.28301E-08 2.37216E-11 9.05108E-14 18 0.00000E+00 -5.26587E-06 -6.16575E-10 -1.22876E-11 6.23057E-14 19 0.00000E+00 1.79651E-07 -1.45866E-09 1.53750E-12 2.06350E-14 28 3.72430E+00 -5.85822E-06 1.31621E-09 -8.53384E-12 4.00651E-14 29 -3.77466E-01 -1.33925E-06 4.45196E-10 -1.16714E-11 3.96620E-14 36 -3.09744E+01 -1.13917E-04 7.15984E-07 -3.16055E-09 7.98698E-12 37 0.00000E+00 -7.03598E-05 4.92379E-07 -2.06869E-09 4.79783E-12 Side number A 12 13 -4.65515E-16 14 -2.80151E-16 18 -9.69398E-17 19 -5.58062E-17 28 -7.21386E-17 29 -6.70449E-17 36 -8.84373E-15 37 -4.76598E-15

[0233] [Table 35] Group number group focus distance G1 139.5772 G2 -35.5358 G3 59.3525 G4 36.9211 G5 -46.2421 G6 768.5642

[0234] [Table 36] Conditional Expression Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 (1) Fnof 1.513 1.205 1.572 1.259 1.463 1.369 1.267 (2) Bfw / fw 0.558 0.681 0.552 0.631 0.553 0.585 0.561 (3) f1 / fw 4.151 5.246 3.941 4.557 3.849 4.150 4.840 (4) (RF+RB) / (RF-RB) -0.475 -0.513 -0.585 -0.091 -0.187 -0.191 -4.873 (5) β2t / β2w 1.701 1.426 1.623 1.467 1.729 1.699 1.503 (6) f3m / fw 0.313 0.359 0.366 0.397 0.320 0.322 0.457 (7) ν1 17.98 20.88 20.88 20.88 20.02 17.98 20.88 (8) ν2 95.10 95.10 68.62 95.10 95.10 95.10 90.19 (9) N 11 11 11 11 11 11 12 (10) f1 / f3 3.366 2.171 0.529 2.190 3.081 3.423 2.352 (11) f3 / f4 0.153 2.197 8.667 1.753 0.186 0.201 1.608 (12) Fwf 21.158 16.873 17.056 17.510 20.531 19.145 17.738 (13) f1m / f2m -0.740 -0.960 -0.510 -0.878 -0.891 -0.683 -0.859 (14) Lw / f1m 12.186 10.459 17.210 12.361 11.677 12.797 11.231 (15) f1m / fw 0.475 0.552 0.337 0.463 0.495 0.453 0.516 (16) f2m / fw -0.642 -0.575 -0.661 -0.528 -0.555 -0.663 -0.601 (17) β4t / β4w 0.973 -1.129 1.455 0.359 0.968 0.969 0.586 (18) Nd_G1ave 1.712 1.671 1.691 1.671 1.712 1.712 1.679 (19) Lw / Yw 7.727 7.699 7.727 7.588 7.703 7.727 7.727

[0235] [Table 37] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Bfw 16.107 19.637 15.902 18.070 15.948 16.889 16.174 fw 28.850 28.845 28.826 28.659 28.833 28.851 28.840 f1 119.762 151.312 113.597 130.592 110.986 119.730 139.577 f3 35.585 69.686 214.762 59.618 36.020 34.983 59.353 f4 232.656 31.724 24.779 34.012 193.489 173.699 36.921 β2t -0.723 -0.415 -0.649 -0.528 -0.752 -0.739 -0.556 β2w -0.425 -0.291 -0.400 -0.360 -0.435 -0.435 -0.370 β4t 0.862 -0.079 -0.505 0.065 0.823 0.824 0.146 β4w 0.886 0.070 -0.347 0.181 0.850 0.850 0.249 f1m 13.716 15.923 9.721 13.280 14.272 13.061 14.883 f2m -18.528 -16.595 -19.048 -15.121 -16.016 -19.119 -17.320 f3m 9.033 10.354 10.555 11.376 9.231 9.286 13.181 RF -84.600 -92.607 -44.597 -251.251 -60.220 -102.436 -86.699 RB 237.614 287.879 170.271 301.394 87.885 150.956 -131.465 Lw 167.148 166.547 167.148 164.148 166.648 167.148 167.148 Yw 21.633 21.633 21.633 21.633 21.633 21.633 21.633

[0236] (summary) A zoom lens according to a first aspect of the present invention comprises: The lens comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a rear group having at least one lens group, When changing magnification from the wide-angle end to the telephoto end, the first lens group moves toward the object side, an aperture stop is disposed on the object side of the third lens group; The zoom lens is characterized by satisfying the following conditional expressions: 0.90 ≦ Fnof ≦ 1.70 (1) 0.45 ≦ Bfw / fw ≦ 0.80 (2) 3.00 ≦ f1 / fw ≦ 6.00 (3) however, Fnof: the composite F-number of the first to fourth lens groups, which is the largest value in the entire magnification range from the wide-angle end to the telephoto end. Bfw: Back focus at the wide-angle end, which is the distance on the optical axis from the image side of the lens closest to the image to the image plane, and is the value when the cover glass thickness is converted into air fw: focal length of the entire zoom lens system at the wide-angle end f1: focal length of the first lens group

[0237] A zoom lens according to a second aspect of the present invention is the zoom lens of the first aspect, further comprising: a single lens or a cemented lens having a concave surface facing the object side, disposed in a lens group having positive refractive power closest to the object side among lens groups disposed closer to the image side than the position of the aperture stop; The following conditional expression may be satisfied: -5.000 ≦ (RF+RB) / (RF-RB) ≦ -0.005 ···(4) however, RF: The radius of curvature of the object-side lens surface in contact with air in a single lens or cemented lens whose object-side surface is concave RB: Radius of curvature of the image-side lens surface in contact with air in the single lens or cemented lens whose object-side surface is concave

[0238] The zoom lens according to the third aspect of the present invention may satisfy the following conditional expression in the first and second aspects. 1.30 ≦ β2t / β2w ≦ 1.85 (5) however, β2t: lateral magnification of the second lens group when focused on infinity at the telephoto end β2w: lateral magnification of the second lens group when focusing on infinity at the wide-angle end

[0239] The zoom lens according to the fourth aspect of the present invention may satisfy the following conditional expression in the first to third aspects. 0.00 < f3m / fw ≦ 0.50 (6) however, f3m: the difference in movement amount between the wide-angle end position of the third lens group and the telephoto end position of the third lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0240] The zoom lens according to the fifth aspect of the present invention may be any of the first to fourth aspects, and may include at least one lens that satisfies the following conditional expression: 15.00 ≦ ν1 ≦ 30.00 (7) however, ν1: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the position of the aperture stop

[0241] The zoom lens according to the sixth aspect of the present invention may be any of the first to fifth aspects, and may include at least one lens that satisfies the following conditional expression: 66.00 ≦ ν2 ≦ 98.55 (8) however, ν2: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the position of the aperture stop

[0242] In the zoom lens according to a seventh aspect of the present invention, in any of the first to sixth aspects, focusing from an object at infinity to an object at a finite distance may be performed by moving, in the optical axis direction, a lens group having negative refractive power adjacent to a lens group having positive refractive power that is located closer to the image side than the position of the aperture stop.

[0243] The zoom lens according to the eighth aspect of the present invention may satisfy the following conditional expression in the first to seventh aspects. 10 ≦ N ≦ 25 (9) however, N: the total number of lenses arranged on the image side of the aperture stop

[0244] The zoom lens according to the ninth aspect of the present invention may satisfy the following conditional expression in the first to eighth aspects. 0.05 ≦ f1 / f3 ≦ 4.50 (10) however, f3: focal length of the third lens group

[0245] The zoom lens according to the tenth aspect of the present invention may satisfy the following conditional expression in the first to ninth aspects. 0.01 ≦ f3 / f4 ≦ 12.00 (11) however, f3: focal length of the third lens group f4: focal length of the fourth lens group

[0246] The zoom lens according to an eleventh aspect of the present invention may satisfy the following conditional expression in the first to tenth aspects. 10.00 ≦ Fwf ≦ 35.00 (12) however, Fwf: composite focal length at the wide-angle end of a lens group that is located closer to the object than the lens group having negative refractive power that is adjacent to the lens group having positive refractive power that is located closer to the image than the position of the aperture stop

[0247] The zoom lens according to the twelfth aspect of the present invention may satisfy the following conditional expression in the first to eleventh aspects. -2.00 ≦ f1m / f2m ≦ -0.02 ···(13) however, f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative f2m: the difference in movement amount between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0248] The zoom lens according to the thirteenth aspect of the present invention may satisfy the following conditional expression in the first to twelfth aspects. 7.05 ≦ Lw / f1m ≦ 20.00 (14) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0249] The zoom lens according to the fourteenth aspect of the present invention may satisfy the following conditional expression in the first to thirteenth aspects. 0.000 < f1m / fw ≦ 0.750 (15) however, f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0250] The zoom lens according to the fifteenth aspect of the present invention may satisfy the following conditional expression in the first to fourteenth aspects. -0.95 ≦ f2m / fw ≦ -0.13 ···(16) however, f2m: the difference in movement amount between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

[0251] The zoom lens according to the sixteenth aspect of the present invention may satisfy the following conditional expression in the first to fifteenth aspects. -3.00 ≦ β4t / β4w ≦ 3.00 ···(17) however, β4t: lateral magnification of the fourth lens group when focusing on infinity at the telephoto end β4w: lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end

[0252] The zoom lens according to the seventeenth aspect of the present invention may satisfy the following conditional expression in the first to sixteenth aspects. 1.600 ≦ Nd_G1ave ≦ 1.780 ···(18) however, Nd_G1ave: average value of refractive index at d line of glass material of each lens constituting the first lens group

[0253] The zoom lens according to the eighteenth aspect of the present invention may satisfy the following conditional expression in the first to seventeenth aspects. 5.50 ≦ Lw / Yw ≦ 8.50 (19) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. Yw: Maximum image height when focused at infinity at the wide-angle end

[0254] An imaging device according to a first aspect of the present invention is an imaging device characterized by comprising a zoom lens according to any one of the first to eighteenth aspects and a solid-state imaging element that converts an optical image formed by the zoom lens into an electrical signal. [Industrial Applicability]

[0255] The zoom lens according to the present invention has a large aperture, yet allows for the realization of a compact zoom lens as a whole, and can effectively correct various aberrations such as spherical aberration and coma over the entire zoom range. In other words, it is suitable for imaging devices using solid-state imaging elements (CCD, CMOS, etc.), such as digital still cameras and digital video cameras, which require compact size. [Explanation of symbols]

[0256] G1 First lens group G2 Second lens group G3 Third lens group G4 4th lens group G5 5th lens group G6 6th lens group GN posterior group S aperture stop CG cover glass IP image plane

Claims

1. The lens comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a rear group having at least one lens group, When changing magnification from the wide-angle end to the telephoto end, the first lens group moves toward the object side, an aperture stop is disposed on the object side of the third lens group; A zoom lens characterized by satisfying the following conditional expression: 0.90≦Fnof≦1.70...(1) 0.45 ≦ Bfw / fw ≦ 0.80 (2) 3.00 ≦ f1 / fw ≦ 6.00 (3) however, Fnof: the composite F-number of the first to fourth lens groups, which is the largest value in the entire magnification range from the wide-angle end to the telephoto end Bfw: back focus at the wide-angle end, which is the distance on the optical axis from the image side of the lens closest to the image to the image plane, and is the value when the cover glass thickness is converted into air fw: focal length of the entire zoom lens system at the wide-angle end f1: focal length of the first lens group

2. a single lens or a cemented lens having a concave surface on the object side is disposed in a lens group having positive refractive power that is closest to the object side among lens groups disposed on the image side of the aperture stop; 2. The zoom lens according to claim 1, wherein the following condition is satisfied: -5.000 ≦ (RF+RB) / (RF-RB) ≦ -0.005...(4) however, RF: the radius of curvature of the object-side lens surface in contact with air in a single lens or cemented lens whose object-side surface is concave RB: the radius of curvature of the image-side lens surface in contact with air in a single lens or cemented lens whose object-side surface is concave

3. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 1.30 ≦ β2t / β2w ≦ 1.85 (5) however, β2t: lateral magnification of the second lens group when focused on infinity at the telephoto end β2w: lateral magnification of the second lens group when focusing on infinity at the wide-angle end

4. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.00 < f3m / fw ≦ 0.50 (6) however, f3m: the difference in movement amount between the wide-angle end position of the third lens group and the telephoto end position of the third lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

5. 2. The zoom lens according to claim 1, comprising at least one lens element that satisfies the following condition: 15.00 ≦ ν1 ≦ 30.00 (7) however, ν1: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the position of the aperture stop

6. 2. The zoom lens according to claim 1, comprising at least one lens element that satisfies the following condition: 66.00 ≦ ν2 ≦ 98.55 (8) however, ν2: Abbe number of a lens having positive refractive power in a lens group having positive refractive power arranged on the image side of the position of the aperture stop

7. 2. The zoom lens according to claim 1, wherein focusing from an object at infinity to an object at a finite distance is performed by moving, in the optical axis direction, a lens group having negative refractive power adjacent to a lens group having positive refractive power that is located closer to the image side than the position of the aperture stop.

8. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 10≦N≦25...(9) however, N: the total number of lenses arranged on the image side of the aperture stop

9. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.05 ≦ f1 / f3 ≦ 4.50 (10) however, f3: focal length of the third lens group

10. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.01 ≦ f3 / f4 ≦ 12.00 (11) however, f3: focal length of the third lens group f4: focal length of the fourth lens group

11. 8. The zoom lens according to claim 7, which satisfies the following condition: 10.00≦Fwf≦35.00 (12) however, Fwf: composite focal length at the wide-angle end of a lens group that is located closer to the object than the lens group having negative refractive power that is adjacent to the lens group having positive refractive power that is located closer to the image than the position of the aperture stop

12. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: -2.00 ≦ f1m / f2m ≦ -0.02 ... (13) however, f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative f2m: the difference in movement amount between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

13. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 7.05 ≦ Lw / f1m ≦ 20.00 (14) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

14. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 0.000 < f1m / fw ≦ 0.750 (15) however, f1m: the difference in movement amount between the wide-angle end position of the first lens group and the telephoto end position of the first lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

15. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: -0.95 ≦ f2m / fw ≦ -0.13 ... (16) however, f2m: the difference in movement amount between the wide-angle end position of the second lens group and the telephoto end position of the second lens group when changing magnification from the wide-angle end to the telephoto end, where the sign of movement toward the object side is positive and the sign of movement toward the image side is negative

16. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: -3.00 ≦ β4t / β4w ≦ 3.00 (17) however, β4t: lateral magnification of the fourth lens group when focused on infinity at the telephoto end β4w: lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end

17. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 1.600≦Nd_G1ave≦1.780 (18) however, Nd_G1ave: average value of refractive index at d line of glass material of each lens constituting the first lens group

18. 2. The zoom lens according to claim 1, wherein the following condition is satisfied: 5.50 ≦ Lw / Yw ≦ 8.50 (19) however, Lw: The distance from the lens surface closest to the object to the image plane at the wide-angle end, calculated by converting the cover glass thickness into air. Yw: Maximum image height when focused at infinity at the wide-angle end

19. 10. An imaging device comprising: the zoom lens according to claim 1; and a solid-state imaging device that converts an optical image formed by the zoom lens into an electrical signal.

Images