Zoom lens and imaging device

Abstract

To provide a compact and small center position variation zoom lens and an imaging device.SOLUTION: A zoom lens includes, 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 the positive refractive power, a fourth lens group (G4) having the negative refractive power, and a fifth lens group (G5). An interval between adjacent lens groups is changed at the time of zooming, and the first lens group (G1) is fixed to the image surface and satisfies a predetermined expression.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a zoom lens and an imaging device. [Background technology]

[0002] With the demand for high image quality in digital cameras leading to larger image sensors and shorter flange focal lengths in mirrorless cameras, there is a demand for more compact optical systems. In addition, cameras mounted on mobile objects such as drones are becoming more common, and there is a demand for zoom lenses with minimal shifts in the center of gravity when zooming in order to achieve stable shooting even while moving.

[0003] As a zoom lens that realizes miniaturization, a positive-lead zoom lens that includes a lens group having positive refractive power closest to the object side is known (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2016 / 157340 [Patent Document 2] JP 2012-113182 A [Patent Document 3] JP 2014-215434 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the zoom lens described in Patent Document 1, the first lens group moves during zooming, so the center of gravity of the zoom lens varies significantly during zooming. If the zoom lens is used as a zoom lens for a camera mounted on a moving object such as a drone, it becomes difficult to suppress the variation in the center of gravity of the moving object.

[0006] In the zoom lenses described in Patent Documents 2 and 3, the first lens group is fixed during zooming. However, the amount of movement of the third lens group relative to the second lens group or the amount of movement of the fourth lens group relative to the second lens group during zooming is not appropriate, so the center of gravity of the zoom lens varies significantly with the movement of these lens groups. When these zoom lenses are used as zoom lenses for cameras mounted on moving objects such as drones, it becomes difficult to suppress the variation in the center of gravity of the moving object.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a compact zoom lens and an image pickup apparatus in which the fluctuation in the position of the center of gravity during zooming is small. [Means for solving the problem]

[0008] In order to achieve the above object, a zoom lens according to the present invention has, 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 negative refractive power, and a fifth lens group, During magnification change, the interval between adjacent lens groups changes, and the first lens group is fixed with respect to the image plane, It is characterized by satisfying the following formula: 0.90 < β3t / β3w / (β2t / β2w) < 1.75 ····(3) 0.75 < β4t / β4w / (β2t / β2w) < 1.30 (4) however, β2w: lateral magnification of the second lens group when focusing on infinity at the wide-angle end β2t: lateral magnification of the second lens group when focusing on infinity at the telephoto end β3w: The lateral magnification of the third lens group when focusing on infinity at the wide-angle end β3t: lateral magnification of the third 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 β4t: The lateral magnification of the fourth lens group when focusing on infinity at the telephoto end

[0009] In order to solve the above problem, an imaging device according to the present invention is characterized by including the above zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. Effect of the Invention

[0010] According to the present invention, it is possible to provide a compact zoom lens and an image pickup apparatus in which the fluctuation in the position of the center of gravity during zooming is small. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a zoom lens according to a first embodiment. [Diagram 2] 4A to 4C are aberration diagrams at the wide-angle end of the zoom lens of Example 1. [Diagram 3] 4A to 4C are aberration diagrams of the zoom lens of Example 1 at a middle focal length position. [Figure 4] 4A to 4C are aberration diagrams at the telephoto end of the zoom lens of Example 1. [Diagram 5] FIG. 11 is a cross-sectional view of a zoom lens according to a second embodiment. [Figure 6] 8A to 8C are aberration diagrams at the wide-angle end of the zoom lens of Example 2. [Figure 7] 8A to 8C are aberration diagrams of the zoom lens of Example 2 at an intermediate focal length position. [Figure 8] 11A to 11C are aberration diagrams at the telephoto end of the zoom lens of Example 2. [Figure 9] FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment. [Figure 10] 11A to 11C are aberration diagrams at the wide-angle end of the zoom lens of Example 3. [Figure 11] 11A to 11C are aberration diagrams of the zoom lens of Example 3 at a middle focal length position. [Figure 12] 11A to 11C are aberration diagrams at the telephoto end of the zoom lens of Example 3. [Figure 13] FIG. 11 is a cross-sectional view of a zoom lens according to a fourth embodiment. [Figure 14]11A to 11C are aberration diagrams at the wide-angle end of the zoom lens of Example 4. [Figure 15] 11A to 11C are aberration diagrams of the zoom lens of Example 4 at a middle focal length position. [Figure 16] 13A to 13C are aberration diagrams at the telephoto end of the zoom lens of Example 4. [Figure 17] 1 is a diagram illustrating an example of a configuration of an imaging device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the zoom lens and the imaging device according to the present invention will be described. However, the zoom lens and the imaging device described below are one aspect of the zoom lens and the imaging device according to the present invention, and the zoom lens and the imaging device according to the present invention are not limited to the following aspects.

[0013] 1. Zoom Lens 1-1.Optical configuration The zoom lens has 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 and fifth lens group having negative refractive power. By adopting this power arrangement, an on-axis light beam close to the effective diameter is incident on the third lens group, so that it is possible to correct spherical aberration in the third lens group. Furthermore, when the zoom lens is divided into an object side group and an image side group, the object side group has positive refractive power, and the image side group has negative refractive power, so that it can be a telephoto zoom lens. With this configuration, the total optical length of the zoom lens can be shortened. In this case, it is preferable that the object side group of the zoom lens is composed of the first to third lens groups, and the image side group is composed of the lens groups from the fourth lens group onwards.

[0014] (1) First lens group The first lens group is the lens group arranged closest to the object side in the zoom lens, and has positive refractive power. The first lens group is preferably composed of, in order from the object side, a lens having negative refractive power (hereinafter referred to as a negative lens) and a lens having positive refractive power (hereinafter referred to as a positive lens), which allows for good correction of chromatic aberration. In addition, it is more preferable that these two lenses are cemented together in order to shorten the overall optical length.

[0015] (2) Second lens group The second lens group is a lens group arranged on the image side of the first lens group, and has negative refractive power. The second lens group preferably has, in order from the object side, a negative lens, a positive lens, and a negative lens, which makes it easier to correct various aberrations. In addition, it is preferable that the lens arranged closest to the image side of the second lens group is a negative meniscus lens with a concave surface on the object side in order to correct various aberrations in the second lens group.

[0016] (3) Third lens group The third lens group is a lens group arranged on the image side of the second lens group and has a positive refractive power. It is preferable that the third lens group has at least one aspheric surface, which facilitates weight reduction of the lens. It is also preferable that the third lens group has four or less lenses, in order to reduce the lens diameter of the third lens group and correct various aberrations.

[0017] (4) Fourth lens group The fourth lens group is a lens group arranged on the image side of the third lens group and has negative refractive power. In order to correct the field curvature of the zoom lens, it is preferable to arrange a negative meniscus lens with a concave surface facing the image side closest to the image side of the fourth lens group.

[0018] (5) Fifth lens group and beyond The fifth lens group is a lens group arranged on the image side of the fourth lens group. It is preferable to arrange a negative lens with a concave surface on the object side closest to the fifth lens group, since this makes it easier to correct the field curvature of the zoom lens. The zoom lens may also include one or more lens groups on the image side of the fifth lens group. It is preferable that the number of lenses arranged between the fifth lens group and the image surface is three or less in total, in order to simplify the control of the variation of the center of gravity. It is also preferable that the zoom lens includes at least one positive lens and at least one negative lens, in order to make it easier to correct chromatic aberration.

[0019] (6) Aperture diaphragm In the zoom lens, the position of the aperture diaphragm is not particularly limited. However, the aperture diaphragm here refers to an aperture diaphragm that determines the light beam diameter of the zoom lens, i.e., an aperture diaphragm that determines the F-number of the zoom lens. The aperture diaphragm is preferably located closer to the image side than the second lens group. Also, it is preferable to locate the aperture diaphragm on the object side of the third lens group or within the third lens group.

[0020] 1-2.Operation (1) Magnification In the zoom lens, the distance between adjacent lens groups changes during zooming. The presence or absence of movement of each lens group, the direction of movement, and the amount of movement are not particularly limited. All lens groups may move along the optical axis during zooming, or at least one of all lens groups may be fixed relative to the image plane during zooming. Here, it is preferable to change the distance between the first lens group and the second lens group so that it is larger at the telephoto end than at the wide-angle end during zooming. This configuration makes it easy to suppress the fluctuation of the center of gravity position, and also makes it possible to achieve a sufficient zoom ratio. It is preferable to move the second lens group so that the distance between the first lens group and the second lens group is maximized at the telephoto end, which makes it easy to suppress the fluctuation of the center of gravity position. It is also preferable to fix the first lens group during zooming in order to suppress the fluctuation of the center of gravity position. It is preferable to move the third lens group and the fifth lens group in a direction different from that of the second lens group, which makes it easy to suppress the fluctuation of the center of gravity position. In addition, when changing magnification from the wide-angle end to the telephoto end, it is preferable that the second lens group moves toward the image side. In addition, as for the lens groups after the third lens group, it is preferable that the third lens group and the fifth lens group move toward the object side, but the movement direction of the other lens groups is not particularly limited. For example, the fourth lens group may move toward the image side. However, from the viewpoint of suppressing the fluctuation of the center of gravity position, it is more preferable that all the lens groups after the third lens group move toward the object side.

[0021] (2)Focus In the zoom lens, the focus group moves on the optical axis when focusing from infinity to a nearby object. The focus group is not particularly limited, and the direction of movement of the focus group during focusing is not particularly limited, but it is preferable that the fourth lens group is the focus group. In this configuration, the fourth lens group can be composed of a lens with a small diameter, so that the focus group can be made small and lightweight. Therefore, the actuator for moving the focus group can be made small, and the zoom lens can be made compact. In addition, in the zoom lens, the fourth lens group is composed of only one lens component, so that the actuator can be made small by reducing the weight of the focus group. In addition, in the zoom lens, it is more preferable that the fourth lens group is composed of only one lens.

[0022] In this specification, the lens component includes a lens and a cemented lens in which a plurality of such lenses are integrated together without an air gap. The lens includes one single lens and a compound lens in which one single lens and a resin are integrated together without an air gap. The single lens is made of one material. Specifically, one cemented lens in which two single lenses are cemented together is counted as one lens component and two lenses. A lens (single lens and compound lens) is counted as one lens component and one lens. Here, the single lens refers to a spherical lens and an aspherical lens (including a compound aspherical lens).

[0023] 1-3. Formula It is preferable that the zoom lens employs the above-mentioned configuration and satisfies at least one of the following expressions.

[0024] 1-3-1.Formula (1) 0.01 <|M3 / M2| < 1.34 (1) however, M2: Amount of movement of the second lens group from the wide-angle end to the telephoto end M3: Distance travelled by the third lens group from the wide-angle end to the telephoto end

[0025] The above formula (1) defines the absolute value of the ratio between the amount of movement of the third lens group from the wide-angle end to the telephoto end and the amount of movement of the second lens group from the wide-angle end to the telephoto end. By satisfying formula (1), it becomes easy to reduce the fluctuation of the center of gravity of the zoom lens. Here, the amount of movement of the lens group refers to the difference between the position of the lens group on the optical axis at the wide-angle end and the position of the lens group on the optical axis at the telephoto end.

[0026] On the other hand, when the value of formula (1) is below the lower limit, the amount of movement of the second lens group becomes large relative to the amount of movement of the third lens group, resulting in large fluctuations in the position of the center of gravity when changing magnification. This is therefore undesirable from the viewpoint of reducing fluctuations in the position of the center of gravity of the zoom lens. On the other hand, when the value of formula (1) is equal to or greater than the upper limit, the amount of movement of the third lens group becomes large relative to the amount of movement of the second lens group, resulting in large fluctuations in the position of the center of gravity when changing magnification. This is therefore undesirable from the viewpoint of reducing fluctuations in the position of the center of gravity of the zoom lens.

[0027] In order to obtain the above effects, the lower limit of formula (1) is preferably 0.20, more preferably 0.40. The upper limit of formula (1) is preferably 1.32, more preferably 1.30. When these preferred lower or upper limits are adopted, the inequality sign (<) in formula (1) may be replaced with an inequality sign with an equal sign (≦). The same principle applies to other formulas.

[0028] 1-3-2.Formula (2) 0.61 <|M5 / M2| < 1.81 (2) however, M2: Amount of movement of the second lens group from the wide-angle end to the telephoto end M5: Distance travelled by the fifth lens group from the wide-angle end to the telephoto end

[0029] The above formula (2) defines the absolute value of the ratio between the amount of movement of the fifth lens group from the wide-angle end to the telephoto end and the amount of movement of the second lens group from the wide-angle end to the telephoto end. By satisfying formula (2), it becomes easy to reduce the fluctuation of the center of gravity of the zoom lens.

[0030] On the other hand, when the value of formula (2) is below the lower limit, the amount of movement of the second lens group relative to the fifth lens group increases, resulting in a large fluctuation in the center of gravity position during zooming. This is therefore undesirable from the standpoint of minimizing the fluctuation in the center of gravity position of the zoom lens. On the other hand, when the value of formula (2) is equal to or greater than the upper limit, the amount of movement of the fifth lens group relative to the second lens group increases, resulting in a large fluctuation in the center of gravity position during zooming. This is therefore undesirable from the standpoint of minimizing the fluctuation in the center of gravity position of the zoom lens.

[0031] In order to obtain the above effects, the lower limit of formula (2) is preferably 0.65, and more preferably 0.70, and the upper limit of formula (2) is preferably 1.70, and more preferably 1.60.

[0032] 1-3-3.Formula (3) 0.90 < β3t / β3w / (β2t / β2w) < 1.75 ····(3) however, β2w: The lateral magnification of the second lens group when focusing on infinity at the wide-angle end β2t: The lateral magnification of the second lens group when focusing on infinity at the telephoto end β3w: The lateral magnification of the third lens group when focusing on infinity at the wide-angle end β3t: The lateral magnification of the third lens group when focusing on infinity at the telephoto end

[0033] The above formula (3) defines the ratio of the lateral magnifications of the second lens group and the third lens group when the zoom lens is changed from the wide-angle end to the telephoto end. By satisfying formula (3), the lateral magnifications of the second lens group and the third lens group can be made appropriate, the amount of movement can be defined while ensuring the zoom lens's variable magnification ratio, and the fluctuation of the center of gravity of the zoom lens can be reduced.

[0034] On the other hand, when the value of formula (3) is equal to or less than the lower limit, the lateral magnification ratio of the second lens group is too large relative to the lateral magnification ratio of the third lens group, so the amount of movement of the second lens group is large, and the fluctuation of the center of gravity position during zooming is large. Therefore, this is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens. On the other hand, when the value of formula (3) is equal to or more than the upper limit, the lateral magnification ratio of the third lens group is too large relative to the lateral magnification ratio of the second lens group, so the amount of movement of the third lens group is large, and the fluctuation of the center of gravity position during zooming is large. Therefore, this is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens.

[0035] In order to obtain the above effects, the lower limit value of formula (3) is preferably 1.00, and more preferably 1.10, and the upper limit value of formula (3) is preferably 1.65, and more preferably 1.60.

[0036] 1-3-4.Formula (4) 0.75 < β4t / β4w / (β2t / β2w) < 1.30 (4) however, β2w: The lateral magnification of the second lens group when focusing on infinity at the wide-angle end β2t: The lateral magnification of the second lens group when focusing on infinity at the telephoto end β4w: The lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end β4t: The lateral magnification of the fourth lens group when focusing on infinity at the telephoto end

[0037] The above formula (4) defines the ratio of the lateral magnifications of the second lens group and the fourth lens group when the zoom lens is changed from the wide-angle end to the telephoto end. By satisfying formula (4), the lateral magnifications of the second lens group and the fourth lens group can be made appropriate, and the amount of movement can be defined while ensuring the zoom lens's variable magnification ratio, and the fluctuation of the center of gravity of the zoom lens can be reduced.

[0038] On the other hand, when the value of formula (4) is equal to or less than the lower limit, the lateral magnification ratio of the second lens group is too large relative to the lateral magnification ratio of the fourth lens group, so the amount of movement of the second lens group is large, and the fluctuation of the center of gravity position during zooming is large. Therefore, this is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens. On the other hand, when the value of formula (4) is equal to or more than the upper limit, the lateral magnification ratio of the fourth lens group is too large relative to the lateral magnification ratio of the second lens group, so the amount of movement of the fourth lens group is large, and the fluctuation of the center of gravity position during zooming is large. Therefore, this is not preferable from the viewpoint of reducing the fluctuation of the center of gravity position of the zoom lens.

[0039] In order to obtain the above effects, the lower limit value of formula (4) is preferably 0.76, and more preferably 0.77, and the upper limit value of formula (4) is preferably 1.20, and more preferably 1.00.

[0040] 1-3-5.Formula (5) Nd2n < 1.80 (5) however, Nd2n: the refractive index at the d-line of the negative lens located closest to the object among at least one negative lens included in the second lens group

[0041] The above formula (5) defines the refractive index at the d-line of the negative lens closest to the object among at least one negative lens included in the second lens group. The specific gravity of a lens tends to increase as the refractive index of its glass material increases. By satisfying formula (5), the weight of the second lens group can be reduced, and the fluctuation of the center of gravity of the zoom lens can be reduced.

[0042] On the other hand, when the value of formula (5) is equal to or greater than the upper limit, it becomes difficult to reduce the weight of the second lens group, and the fluctuation in the position of the center of gravity of the zoom lens increases. In order to obtain the above effect, the upper limit of formula (5) is preferably 1.78, and more preferably 1.76.

[0043] In order to achieve good correction of field curvature, the lower limit of expression (5) is preferably 1.40, more preferably 1.50, and even more preferably 1.55.

[0044] 1-3-6.Formula (6) 0.10 < | f2 | / f1 < 0.40 (6) however, f1: focal length of the first lens group f2: focal length of the second lens group

[0045] The above formula (6) defines the ratio of the focal length of the second lens group to the focal length of the first lens group. By satisfying formula (6), it is possible to correct various aberrations while shortening the overall optical length, making it possible to miniaturize the zoom lens.

[0046] On the other hand, if the value of formula (6) is equal to or less than the lower limit, the refractive power of the first lens group is weak relative to the refractive power of the second lens group, the telephoto effect is weak, and it becomes difficult to shorten the overall optical length. This is therefore undesirable from the viewpoint of making the zoom lens compact. On the other hand, if the value of formula (6) is equal to or greater than the upper limit, the refractive power of the first lens group becomes too strong relative to the refractive power of the second lens group, and it becomes difficult to correct distortion at the wide-angle end and spherical aberration and axial chromatic aberration at the telephoto end, which is undesirable.

[0047] In order to obtain the above-mentioned effects, the lower limit value of the formula (6) is preferably 0.15, and more preferably 0.20, and the upper limit value of the formula (6) is preferably 0.35, and more preferably 0.30.

[0048] 1-3-7. Formula (7) 1.50 < β3t / β3w < 2.50 (7) however, β3w: The lateral magnification of the third lens group when focusing on infinity at the wide-angle end β3t: The lateral magnification of the third lens group when focusing on infinity at the telephoto end

[0049] The above formula (7) defines the lateral magnification ratio of the third lens group when the zoom lens is changed from the wide-angle end to the telephoto end. By satisfying formula (7), it is possible to achieve both a sufficient zooming effect and a short overall optical length, making it possible to miniaturize the zoom lens.

[0050] On the other hand, when the value of formula (7) is equal to or less than the lower limit, the lateral magnification ratio of the third lens group becomes small, making it difficult to ensure a sufficient zoom ratio. On the other hand, when the value of formula (7) is equal to or greater than the upper limit, the lateral magnification ratio of the third lens group becomes large, increasing the amount of movement of the third lens group. This increases the overall optical length, which is undesirable from the viewpoint of making the zoom lens compact.

[0051] In order to obtain the above effects, the lower limit value of formula (7) is preferably 1.60, and more preferably 1.70, and the upper limit value of formula (7) is preferably 2.40, and more preferably 2.30.

[0052] 1-3-8. Formula (8) 0.30 < | f2 | / fw < 1.00 (8) however, f2: focal length of the second lens group fw: focal length of the zoom lens when focused at infinity at the wide-angle end

[0053] The above formula (8) defines the ratio between the focal length of the second lens group and the focal length of the zoom lens when focused on infinity at the wide-angle end. By satisfying formula (8), it is possible to both correct various aberrations and reduce the size of the zoom lens.

[0054] On the other hand, if the value of formula (8) is below the lower limit, the refractive power of the second lens group becomes too strong, making it difficult to correct curvature of field and distortion at the wide-angle end, which is undesirable. On the other hand, if the value of formula (8) is above the upper limit, the refractive power of the second lens group becomes too weak, and in order to achieve a predetermined zoom ratio, the amount of movement of the second lens group during zooming must be increased, which increases the overall optical length. Therefore, this is undesirable from the perspective of making the zoom lens compact.

[0055] In order to obtain the above-mentioned effects, the lower limit value of the formula (8) is preferably 0.40, and more preferably 0.50, and the upper limit value of the formula (8) is preferably 0.90, and more preferably 0.80.

[0056] 1-3-9. Formula (9) 0.50 < f1 / ft < 2.00 (9) however, f1: focal length of the first lens group ft: focal length of the zoom lens when focused at infinity at the telephoto end

[0057] The above formula (9) defines the ratio between the focal length of the first lens group and the focal length of the zoom lens when focused at infinity at the telephoto end. By satisfying formula (9), it is possible to both correct various aberrations and reduce the size of the zoom lens.

[0058] On the other hand, if the value of formula (9) is equal to or less than the lower limit, the refractive power of the first lens group becomes too strong, making it difficult to correct spherical aberration and axial chromatic aberration at the telephoto end, which is not preferable.On the other hand, if the value of formula (9) is equal to or more than the upper limit, the refractive power of the first lens group becomes too weak, making it difficult to shorten the total optical length at the telephoto end, which is not preferable.

[0059] In order to obtain the above-mentioned effects, the lower limit value of the formula (9) is preferably 0.70, and more preferably 0.90, and the upper limit value of the formula (9) is preferably 1.70, and more preferably 1.40.

[0060] 1-3-10. Formula (10) 0.50 < f4 / f2 < 3.50 (10) however, f2: focal length of the second lens group f4: focal length of the fourth lens group

[0061] The above formula (10) defines the ratio of the focal length of the fourth lens group to the focal length of the second lens group. By satisfying formula (10), it is possible to both correct various aberrations and reduce the size of the zoom lens.

[0062] On the other hand, when the value of formula (10) is equal to or less than the lower limit, the refractive power of the fourth lens group relative to the second lens group becomes too strong, making it difficult to correct spherical aberration, astigmatism, and curvature of field, which is undesirable. On the other hand, when the value of formula (10) is equal to or greater than the upper limit, the refractive power of the fourth lens group relative to the second lens group becomes too weak, making the fourth lens group large and the diameter of the lens barrel large, which is undesirable. Furthermore, when the fourth lens group is used as a focus group, the amount of movement of the fourth lens group during focusing becomes large, making it difficult to shorten the overall optical length.

[0063] In order to obtain the above effects, the lower limit of formula (10) is preferably 1.00, and more preferably 1.50, and the upper limit of formula (10) is preferably 3.00, and more preferably 2.50.

[0064] 1-3-11. Formula (11) 4.55 < | f5 | / f3 < 7.10 (11) however, f3: focal length of the third lens group f5: focal length of the fifth lens group

[0065] The above formula (11) defines the ratio of the focal length of the fifth lens group to the focal length of the third lens group. By satisfying formula (11), it is possible to both correct various aberrations and reduce the size of the zoom lens.

[0066] On the other hand, if the value of formula (11) is equal to or less than the lower limit, the refractive power of the fifth lens group relative to the third lens group becomes too strong, making it difficult to correct spherical aberration, astigmatism, and curvature of field, which is undesirable. On the other hand, if the value of formula (11) is equal to or greater than the upper limit, the refractive power of the third lens group becomes too strong relative to the fifth lens group, making it difficult to correct spherical aberration, and making it difficult to simultaneously correct various aberrations and reduce the size of the zoom lens.

[0067] In order to obtain the above effects, the lower limit of formula (11) is preferably 4.70, and more preferably 4.85, and the upper limit of formula (11) is preferably 7.00, and more preferably 6.90.

[0068] 2. Imaging device Next, an imaging device according to the present invention will be described. The imaging device according to the present invention is characterized by comprising the zoom lens according to the present invention and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. The imaging element is preferably provided on the image side of the zoom lens.

[0069] Here, the imaging element is not particularly limited, and solid-state imaging elements such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor can also be used. The imaging device according to the present invention is suitable for imaging devices using these solid-state imaging elements, such as digital cameras and video cameras. The imaging device can be applied to various imaging devices, such as single-lens reflex cameras, mirrorless single-lens cameras, digital still cameras, surveillance cameras, car-mounted cameras, and drone-mounted cameras. These imaging devices may be lens-interchangeable imaging devices, or lens-fixed imaging devices in which the lens is fixed to the housing. In particular, the zoom lens according to the present invention is suitable for use as a zoom lens in an imaging device equipped with a large-sized imaging element such as a full-size. The zoom lens is small and lightweight overall, and has high optical performance, so that a high-quality image can be obtained even when used as a zoom lens for such imaging devices.

[0070] 17 is a diagram illustrating an example of the configuration of the imaging device 1. The camera 2 has a detachable zoom lens 3, an imaging element 21 (CCD sensor or CMOS sensor) arranged on an image plane IP of the zoom lens 3, and a cover glass CG arranged on the object side of the imaging element 21. The zoom lens 3 has an aperture diaphragm 31.

[0071] Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. EXAMPLES

[0072] (1) Optical configuration 1 is a cross-sectional view of a zoom lens according to a first embodiment of the present invention at the wide-angle end, the intermediate focal length end, and the telephoto end when focusing on infinity. The zoom lens 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 negative refractive power, and a fifth lens group G5 having positive refractive power.

[0073] During zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 first moves toward the object side and then moves toward the image side, and the fifth lens group G5 moves toward the object side. Also, during zooming, the third lens group G3 and the fifth lens group G5 move on the same trajectory in a different direction from the second lens group G2.

[0074] When focusing from an object at infinity to a close object, the fourth lens group G4 moves along the optical axis.

[0075] An aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0076] The configuration of each lens group will now be described.

[0077] The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive meniscus lens are cemented together.

[0078] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens which is a composite aspheric surface having an aspheric surface on the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with a concave shape on the object side.

[0079] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a biconvex lens, a negative meniscus lens having a convex shape facing the object side, and a cemented lens in which the biconvex lenses are cemented together.

[0080] The fourth lens group G4 is composed of a negative meniscus lens having a convex shape facing the object side.

[0081] The fifth lens group G5 is composed of, in order from the object side, a biconcave lens and a biconvex lens.

[0082] In Fig. 1, "IP" denotes an image plane, specifically, an imaging surface of a solid-state imaging element such as a CCD sensor or a CMOS sensor, or a film surface of a silver halide film. A parallel plate having no substantial refractive power, such as a cover glass CG, is provided on the object side of the image plane IP. In Fig. 1, the reference numerals for the lenses constituting each lens group are omitted. These points are the same in the lens cross-sectional views shown in other embodiments, and therefore further explanation will be omitted.

[0083] (2) Numerical examples Next, we will explain numerical examples to which specific numerical values ​​of the zoom lens are applied. The following shows "Lens Data", "Specification Table", "Variable Distance", "Aspheric Coefficient", and "Lens Group Data". The values ​​of each formula (Table 1) are summarized after Example 4.

[0084] In (Lens Data), "Surface Number" is the order of the lens surface counted from the object side, "R" is the radius of curvature of the lens surface, "D" is the lens thickness or air space on the optical axis, "Nd" is the refractive index at the d-line (wavelength λ=587.6 nm), and "ABV" is the Abbe number at the d-line. In the "Surface Number" column, "ASPH" next to the surface number indicates that the lens surface is aspheric, and "STOP" indicates that the surface is an aperture stop. In the "D" column, "D(3)", "D(12)", etc. indicate that the spacing on the optical axis of the lens surface is a variable spacing that changes when the magnification is changed. In the "Curvature Radius" column, "0.0000" means infinity, meaning that the lens surface is flat.

[0085] In the specifications table, "f" is the focal length of the zoom lens, "Fno" is the F-number, "ω" is the half angle of view, "Y" is the image height, and "TL" is the total optical length. The values ​​shown are for the wide-angle end, mid-range focal length, and telephoto end, respectively.

[0086] (Variable interval) shows the values ​​when focusing on infinity at the wide-angle end, mid-focal length, and telephoto end, respectively.

[0087] (Aspherical coefficient) indicates the aspherical coefficient when the aspherical shape is defined as follows. Here, x is the amount of displacement from the reference surface in the optical axis direction, r is the paraxial radius of curvature, H is the height from the optical axis in a direction perpendicular to the optical axis, k is the conical coefficient, and An is the n-th order aspherical coefficient. In the "Aspherical coefficient" table, "E±XX" represents exponential notation, and "×10 ±XX " means.

[0088]

number

[0089] The items in these tables are the same as those in the tables shown in the other embodiments, so the explanation will be omitted below.

[0090] 2, 3 and 4 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length and the telephoto end when focusing on infinity. The longitudinal aberration diagrams shown in each diagram are, from the left side of the drawing, spherical aberration (mm), astigmatism (mm) and distortion (%), respectively. In the spherical aberration diagrams, the solid line shows the spherical aberration at the d-line (wavelength 587.6 nm), the dashed line shows the spherical aberration at the F-line (wavelength 486.1 nm) and the dotted line shows the spherical aberration at the C-line (wavelength 656.3 nm). In the astigmatism diagrams, the vertical axis shows the image height (Y) and the horizontal axis shows the defocus, the solid line shows the sagittal image plane (S) of the d-line and the dashed line shows the meridional image plane (T) of the d-line. In the distortion diagrams, the vertical axis shows the image height (Y) and the horizontal axis shows the distortion aberration. These matters are the same in each aberration diagram shown in the other examples, so the explanation will be omitted below.

[0091] (Lens data) Surface number RD Nd ABV 1 44.7404 1.5000 1.84666 23.78 2 29.2689 9.6562 1.72916 54.67 3 210.0434 D( 3) 4ASPH 219.3135 0.2000 1.53610 41.21 5 135.4493 1.1000 1.72916 54.67 6 16.3919 7.8572 7 -65.7596 1.0000 1.79952 42.22 8 40.4329 0.1500 9 30.4699 5.1444 1.85025 30.05 10 -53.5371 1.5762 11 -25.7590 1.1000 1.53996 59.46 12 -241.3400 D(12) 13STOP 0.0000 1.0000 14ASPH 23.8447 4.1759 1.59201 67.02 15ASPH -115.0000 3.8272 16 98.7904 1.8788 1.48749 70.44 17 -1054.0068 0.1500 18 51.4075 1.0000 1.80610 40.73 19 15.1176 6.3527 1.49700 81.61 20 -27.4930 D(20) 21ASPH 98.8684 1.1000 1.59201 67.02 22ASPH 20.2905 D(22) 23 -58.0785 1.2000 1.66680 33.05 24 142.2575 0.1500 25 55.0689 5.1088 1.65160 58.55 26 -61.2588 D(26) 27 0.0000 2.5000 1.51680 64.20 28 0.0000 1.0000 29 0.0000

[0092] (Specifications table) Wide-angle end Mid-range Telephoto end f 28.8419 44.3139 72.7392 Fno 4.1128 4.1402 4.1053 ω 37.8908 26.1810 15.9258 Y 20.2060 21.4087 21.6330 TL 130.000 130.000 130.000

[0093] (Variable interval) Wide-angle end Mid-range Telephoto end D(3) 0.9000 7.8954 15.2490 D(12) 27.4467 14.6673 2.2598 D(20) 1.8078 4.2359 9.9958 D(22) 16.5562 14.1281 8.3682 D(26) 24.5619 30.3458 35.3998

[0094] (aspheric coefficients) Surface number K A4 A6 A8 A10 4 -10.00000E-01 6.50835E-06 -1.36628E-09 -1.31475E-11 4.28156E-14 14 2.34041E-01 -8.34938E-06 -5.47995E-08 9.99049E-10 -9.61630E-12 15 0.00000E+00 1.79671E-05 -3.47440E-08 7.50078E-10 -8.76122E-12 21 4.87803E-01 -2.38122E-05 1.03424E-07 5.30360E-10 -3.40024E-12 22 -1.10518E-01 -1.88271E-05 4.69047E-08 8.52789E-10 -6.43438E-12

[0095] (Lens group data) group focal length G1 84.44 G2 -20.02 G3 23.78 G4 -43.35 G5 150.55 EXAMPLES

[0096] (1) Optical configuration 5 is a cross-sectional view of a zoom lens according to Example 2 of the present invention at the wide-angle end, the intermediate focal length, and the telephoto end when focusing on infinity. The zoom lens 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 negative refractive power, and a fifth lens group G5 having positive refractive power.

[0097] When zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 first moves toward the object side and then moves toward the image side, and the fifth lens group G5 moves toward the object side.

[0098] When focusing from an object at infinity to a close object, the fourth lens group G4 moves along the optical axis.

[0099] An aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0100] The configuration of each lens group will now be described.

[0101] The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive meniscus lens are cemented together.

[0102] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens which is a composite aspheric surface having an aspheric surface on the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with a concave shape on the object side.

[0103] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a biconvex lens, and a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a biconvex lens are cemented together.

[0104] The fourth lens group G4 is composed of a negative meniscus lens having a convex shape facing the object side.

[0105] The fifth lens group G5 is composed of, in order from the object side, a biconcave lens and a biconvex lens.

[0106] (2) Numerical examples Next, as numerical examples to which specific numerical values ​​of the zoom lens are applied, "Lens Data", "Specification Table", "Variable Distance", "Aspheric Coefficient", and "Lens Group Data" are shown. Also, Fig. 6, Fig. 7, and Fig. 8 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length, and the telephoto end when focusing on infinity.

[0107] (Lens data) Surface number RD Nd ABV 1 43.6206 1.5000 1.84666 23.78 2 29.1642 9.7000 1.72916 54.67 3 211.9514 D(3) 4ASPH 338.8778 0.2000 1.53610 41.21 5 140.3579 1.1000 1.72916 54.67 6 16.8372 8.2077 7 -56.6957 1.0000 1.79952 42.22 8 47.3109 0.1000 9 34.9299 6.2583 1.85025 30.06 10 -45.5169 1.3323 11 -25.7327 1.1000 1.53996 59.46 12 -260.9036 D(12) 13STOP 0.0000 1.0000 14ASPH 23.5767 4.1015 1.59201 67.02 15ASPH -148.5272 3.1447 16 59.2940 1.8766 1.48749 70.44 17 208.4901 0.1993 18 40.9023 1.0000 1.80610 40.73 19 14.1474 8.3877 1.49700 81.61 20 -31.5958 D(20) 21ASPH 120.4655 1.1000 1.59201 67.02 22ASPH 21.3635D(22) 23 -41.6645 1.2000 1.66680 33.05 24 265.6613 1.8599 25 71.8601 5.6514 1.65160 58.55 26 -46.2660 D(26) 27 0.0000 2.5000 1.51680 64.20 28 0.0000 1.0000 29 0.0000

[0108] (Specifications table) Wide-angle end Mid-range Telephoto end f 28.8361 44.3099 72.7320 Fno 4.0833 4.2061 4.1269 ω 37.8973 26.2598 15.9475 Y 20.2060 21.4087 21.6330 TL 130.000 130.000 130.000

[0109] (Variable interval) Wide-angle end Mid-range Telephoto end D(3) 0.9000 6.3702 13.8327 D(12) 27.4863 14.4033 1.6217 D(20) 2.2215 4.1491 9.5833 D(22) 12.9683 13.4442 7.4664 D(26) 22.9045 28.1138 33.9765

[0110] (aspheric coefficients) Surface number K A4 A6 A8 A10 4 1.00000E+00 5.98733E-06 -2.42232E-09 -5.90416E-12 2.53587E-14 14 3.09547E-01 -7.15932E-06 -5.93023E-08 9.23203E-10 -5.81614E-12 15 0.00000E+00 1.38775E-05 -5.39596E-08 9.99946E-10 -6.34338E-12 21 -2.02913E+01 -2.53852E-05 6.78813E-08 2.47336E-10 7.35212E-13 22 1.14267E-02 -1.65687E-05 4.22860E-08 1.03838E-10 2.85655E-13

[0111] (Lens group data) group focal length G1 80.93 G2 -20.22 G3 23.83 G4 -44.05 G5 163.66 EXAMPLES

[0112] (1) Optical configuration 9 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention at the wide-angle end, the intermediate focal length end, and the telephoto end when focusing on infinity. The zoom lens 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 negative refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power.

[0113] When zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 moves toward the object side.

[0114] When focusing from an object at infinity to a close object, the fourth lens group G4 moves along the optical axis.

[0115] An aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0116] The configuration of each lens group will now be described.

[0117] The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive meniscus lens are cemented together.

[0118] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens which is a composite aspheric surface having an aspheric surface on the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with a concave shape on the object side.

[0119] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a positive meniscus lens with a convex shape facing the object side, and a cemented lens in which a negative meniscus lens with a convex shape facing the object side and a biconvex lens are cemented together.

[0120] The fourth lens group G4 is composed of a biconcave lens.

[0121] The fifth lens group G5 is composed of a negative meniscus lens with a concave surface on the object side.

[0122] The sixth lens group G6 is composed of a biconvex lens.

[0123] (2) Numerical examples Next, as numerical examples to which specific numerical values ​​of the zoom lens are applied, "Lens Data", "Specification Table", "Variable Distance", "Aspheric Coefficient", and "Lens Group Data" are shown. Also, Fig. 10, Fig. 11, and Fig. 12 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length, and the telephoto end when focusing on infinity.

[0124] (Lens data) Surface number R D Nd ABV 1 44.3293 1.5000 1.84666 23.78 2 30.4056 9.7000 1.72916 54.67 3 191.7434 D( 3) 4ASPH 249.4728 0.2000 1.53610 41.21 5 129.7371 1.1000 1.72916 54.67 6 17.3339 8.3145 7 -61.5728 1.0000 1.79952 42.22 8 40.6391 0.1014 9 34.1707 9.5158 1.85025 30.06 10 -45.3529 1.2913 11 -25.9370 1.1000 1.53996 59.46 12 -416.1649 D(12) 13STOP 0.0000 1.0000 14ASPH 24.3725 4.0117 1.59201 67.02 15ASPH -217.8851 1.8391 16 31.5481 2.2990 1.48749 70.44 17 61.4089 0.7670 18 34.2186 1.0000 1.80610 40.73 19 13.3230 8.1146 1.49700 81.61 20 -44.6110 D(20) 21ASPH -3358.0083 1.1000 1.59201 67.02 22ASPH 24.9470 D(22) 23 -38.6437 1.2000 1.75211 25.05 24 -68.2349 D(24) 25 71.6344 5.9420 1.59349 67.00 26 -77.4202 D(26) 27 0.0000 2.5000 1.51680 64.20 28 0.0000 1.0000 29 0.0000

[0125] (Specifications table) Wide-angle end Mid-range Telephoto end f 28.8400 44.3100 77.2417 Fno 4.4078 4.3636 4.5054 ω 37.8977 26.4518 15.2674 Y 20.2060 21.4087 21.6330 TL 140.170 140.170 140.170

[0126] (Variable interval) Wide-angle end Mid-range Telephoto end D(3) 0.9000 8.4515 14.0365 D(12) 30.6905 16.6590 1.1333 D(20) 2.3398 3.6644 9.4586 D(22) 13.3101 14.3464 3.4960 D(24) 10.8331 5.7620 6.2517 D(26) 17.5000 26.6901 41.1974

[0127] (aspheric coefficients) Surface number K A4 A6 A8 A10 4 10.00000E-01 5.13382E-06 -7.00902E-10 -8.03582E-12 2.14741E-14 14 4.65713E-01 -4.77138E-06 -5.97403E-08 7.25836E-10 -3.26740E-12 15 0.00000E+00 8.81851E-06 -5.28576E-08 8.45021E-10 -3.73875E-12 21 -1.11036E+05 -2.23784E-05 6.39109E-08 -1.06215E-09 1.11899E-11 22 5.18849E-01 -9.84438E-06 2.71436E-08 -8.81225E-10 7.85457E-12

[0128] (Lens group data) group focal length G1 84.19 G2 -20.07 G3 24.12 G4 -41.82 G5 -120.58 G6 63.64 EXAMPLES

[0129] (1) Optical configuration 13 is a cross-sectional view of a zoom lens according to a fourth embodiment of the present invention at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens 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 negative refractive power, and a fifth lens group G5 having positive refractive power.

[0130] When zooming from the wide-angle end to the telephoto end, the first lens group G1 does not move and is fixed with respect to the image plane, the second lens group G2 moves toward the image side, the third lens group G3 moves toward the object side, the fourth lens group G4 first moves toward the object side and then moves toward the image side, and the fifth lens group G5 moves toward the object side.

[0131] When focusing from an object at infinity to a close object, the fourth lens group G4 moves along the optical axis.

[0132] An aperture stop S is disposed adjacent to the object side of the third lens group G3.

[0133] The configuration of each lens group will now be described.

[0134] The first lens group G1 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive meniscus lens are cemented together.

[0135] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens which is a composite aspheric surface having an aspheric surface on the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens with a concave shape on the object side.

[0136] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a biconvex lens, a positive meniscus lens, and a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a biconvex lens are cemented together.

[0137] The fourth lens group G4 is composed of a negative meniscus lens having a convex shape facing the object side.

[0138] The fifth lens group G5 is composed of, in order from the object side, a biconcave lens and a biconvex lens.

[0139] (2) Numerical examples Next, as numerical examples to which specific numerical values ​​of the zoom lens are applied, "Lens Data", "Specification Table", "Variable Distance", "Aspheric Coefficient", and "Lens Group Data" are shown. Also, Fig. 14, Fig. 15, and Fig. 16 show longitudinal aberration diagrams of the zoom lens at the wide-angle end, the intermediate focal length, and the telephoto end when focusing on infinity.

[0140] (Lens data) Surface number RD Nd ABV 1 43.0465 1.5000 1.84666 23.78 2 30.1347 9.6239 1.72916 54.67 3 134.2961 D(3) 4ASPH 234.9171 0.2000 1.53610 41.21 5 109.6679 1.1000 1.72916 54.67 6 16.7104 8.2392 7 -61.0213 1.0000 1.79952 42.22 8 46.6663 0.1000 9 33.5592 5.7207 1.85025 30.06 10 -50.3994 1.6670 11 -25.5775 1.1000 1.53996 59.46 12 -161.3548 D(12) 13STOP 0.0000 1.0000 14ASPH 22.9783 4.0698 1.59201 67.02 15ASPH -241.7026 2.7715 16 47.9347 2.0352 1.48749 70.44 17 160.7628 0.2598 18 38.0250 1.0000 1.80610 40.73 19 13.4980 6.9174 1.49700 81.61 20 -32.4775 D(20) 21ASPH 109.8327 1.1000 1.59201 67.02 22ASPH 19.3014D(22) 23 -62.1818 1.2000 1.66680 33.05 24 219.7388 1.3657 25 58.8156 5.2815 1.65160 58.55 26 -66.8569 D(26) 27 0.0000 2.5000 1.51680 64.20 28 0.0000 1.0000 28 0.0000

[0141] (Specifications table) Wide-angle end Mid-range Telephoto end f 28.8359 44.3130 72.7244 Fno 4.0939 4.0016 3.9376 ω 37.9013 26.3367 15.9533 Y 20.2060 21.4087 21.6330 TL 130.000 130.000 130.000

[0142] (Variable interval) Wide-angle end Mid-range Telephoto end D(3) 0.9000 10.1487 18.3918 D(12) 28.0453 14.6530 1.8027 D(20) 1.9434 3.9552 8.1997 D(22) 16.9047 11.0041 3.8517 D(26) 21.4551 29.4876 37.0026

[0143] (aspheric coefficients) Surface number K A4 A6 A8 A10 4 1.00000E+00 7.65705E-06 -5.39614E-10 -1.56730E-11 4.65804E-14 14 3.39394E-01 -6.86626E-06 -5.42233E-08 9.15665E-10 -7.68331E-12 15 0.00000E+00 1.70457E-05 -4.71781E-08 9.32692E-10 -8.15032E-12 21 2.77018E+00 -2.40136E-05 6.17240E-08 6.37727E-11 3.27147E-12 22 -1.12409E-01 -1.84230E-05 1.33924E-08 -9.77149E-11 1.99878E-12

[0144] (Lens group data) group focal length G1 91.18 G2 -21.14 G3 23.26 G4 -39.73 G5 130.36

[0145] [Table 1] Formula Example 1 Example 2 Example 3 Example 4 Equation (1) |M3 / M2| 0.76 1.00 1.25 0.50 Equation (2) |M5 / M2| 0.76 0.86 1.46 0.89 Equation (3) β3t / β3w / (β2t / β2w) 1.34 1.35 1.54 1.25 Equation (4) β4t / β4w / (β2t / β2w) 0.79 0.81 0.97 0.79 Equation (5) Nd2n 1.73 1.73 1.73 1.73 Equation (6) |f2| / f1 0.24 0.25 0.24 0.23 Equation (7) β3t / β3w 1.84 1.83 2.06 1.80 Equation (8) |f2| / fw 0.69 0.70 0.70 0.73 Equation (9) f1 / ft 1.16 1.11 1.09 1.25 Equation (10) f4 / f2 2.17 2.18 2.08 1.88 Equation (11) |f5| / f3 6.33 6.87 5.00 5.61 [Industrial Applicability]

[0146] The zoom lens according to the present invention can be suitably applied as an imaging optical system for imaging devices such as film cameras, digital still cameras, and digital video cameras. [Explanation of symbols]

[0147] S Aperture CG ···Cover glass IP...Image plane G1: First lens group G2: Second lens group G3: Third lens group G4: Fourth lens group G5: Fifth lens group G6: 6th lens group 1. Imaging device 2. Camera 3. Lens 21 Imaging element

Claims

1. A zoom lens having, 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 negative refractive power, and a fifth lens group; During magnification change, the interval between adjacent lens groups changes, and the first lens group is fixed with respect to the image plane, A zoom lens that satisfies the following formula: 0.90 < β3t / β3w / (β2t / β2w) < 1.75 (3 ） 0.75 < β4t / β4w / (β2t / β2w) < 1.30 (4 ） 1.80 ≦ β3t / β3w < 2.50 (7) 1.88 ≦ f4 / f2 < 3.50 (10) however, β2w: the lateral magnification of the second lens group when focusing on infinity at the wide-angle end β2t: lateral magnification of the second lens group when focusing on infinity at the telephoto end β3w: the lateral magnification of the third lens group when focusing on infinity at the wide-angle end β3t: lateral magnification of the third lens group when focusing on infinity at the telephoto end β4w: the lateral magnification of the fourth lens group when focusing on infinity at the wide-angle end β4t: lateral magnification of the fourth lens group when focusing on infinity at the telephoto end f2: focal length of the second lens group f4: the focal length of the fourth lens group

2. 2. The zoom lens according to claim 1, which satisfies the following formula: Nd2n < 1.80 (5) however, Nd2n: the refractive index at the d-line of the negative lens arranged closest to the object side among at least one negative lens included in the second lens group

3. 3. The zoom lens according to claim 1, which satisfies the following formula: 0.10 < | f2 | / f1 < 0.40 (6) however, f1: focal length of the first lens group

4. 4. The zoom lens according to claim 1, which satisfies the following formula: 0.30 < | f2 | / fw < 1.00 (8) however, fw: focal length of the zoom lens when focused on infinity at the wide-angle end

5. 5. The zoom lens according to claim 1, which satisfies the following formula: 0.50 < f1 / ft < 2.00 (9) however, f1: focal length of the first lens group ft: focal length of the zoom lens when focused at infinity at the telephoto end

6. 6. The zoom lens according to claim 1, wherein the third lens group has a positive lens having at least one aspheric surface.

7. 7. The zoom lens according to claim 1, wherein the fourth lens group moves along the optical axis during focusing.

8. 8. The zoom lens according to claim 1, wherein the fourth lens group is made up of only one lens component.

9. 9. The zoom lens according to claim 1, further comprising at least one positive lens and at least one negative lens between the fifth lens group and the image surface, for a total of three lenses or less.

10. 10. An imaging apparatus comprising: the zoom lens according to claim 1; and an image sensor on an image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

Images