Optical system and imaging device

Abstract

To provide a zoom lens and an imaging device which are reduced in size and weight, yet have higher image forming performance in the entire zoom range.SOLUTION: Provided is a zoom lens composed of, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a rear group (G6), with which the interval between the adjacent lenses changes when zooming, and which satisfies a prescribed conditional expression. Also provided is an imaging device that includes the zoom lens and an imaging element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Imaging devices using various solid-state imaging elements, such as video cameras, digital still cameras, single-lens reflex cameras, and single-lens non-reflex cameras, have become widespread. As imaging optical systems for use in these imaging devices, there is a demand for high-resolution, compact zoom lenses that can cover a wide imaging angle of view. Furthermore, there is a demand for such zoom lenses to achieve high-speed, high-precision autofocus.

[0003] In recent years, imaging devices with video capture capabilities as well as still images have become widespread. While phase-difference autofocusing is used for still image capture, contrast autofocusing is often used for video capture. For example, by repeatedly performing a series of operations, such as creating out-of-focus and in-focus states while rapidly wobbling a portion of the lens group (focus lens group) along the optical axis, detecting signal components in a certain frequency band in a portion of the image area from the output signal of the image sensor, determining the optimal position of the focus lens group for achieving the in-focus state, and moving the focus lens group to that optimal position, it becomes possible to continuously autofocus on a subject even when capturing video.

[0004] However, wobbling can sometimes cause the size of the image corresponding to the subject to change. This is primarily due to the fact that movement of the focus lens group along the optical axis changes the focal length of the entire lens system. Large fluctuations in the angle of view due to wobbling can create an unnatural feeling in the captured image. One way to alleviate this unnatural feeling is to use a lens group behind the aperture as the focus lens group. As non-reflex cameras become more compact, there is a demand for smaller zoom lenses themselves, which naturally requires smaller and lighter focus lens groups. Furthermore, even greater compactness and lighter focus lens groups are desirable for high-speed, continuous movement of the focus lens group during video capture.

[0005] Conventionally, image sensors that receive optical images and convert them into electrical image signals have limitations due to the efficient capture of incident light using on-chip microlenses and other devices. Therefore, it has been desirable to enlarge the exit pupil on the lens side to a certain extent to ensure telecentricity of the light beam incident on the image sensor. However, with the recent improvement in the numerical aperture of image sensors and advances in the design flexibility of on-chip microlenses, the limitations on the exit pupil required on the lens side have been reduced. For this reason, various inventions have been developed to ensure telecentricity by placing a positive lens group behind the zoom lens. However, this has become less and less common in recent years. By placing a negative lens group behind the lens, even when light beams are obliquely incident on the image sensor, peripheral shading due to mismatching of the pupil with the on-chip microlens is less noticeable. Furthermore, advances and improvements in software and camera systems have made it possible to correct distortion, even if it is relatively large and previously noticeable, through image processing.

[0006] Against this background, for example, Patent Document 1 proposes a wide-angle zoom lens consisting of six groups (negative-positive-negative-positive-negative-positive) with the fifth lens group serving as a focus lens group. The wide-angle zoom lens disclosed in Patent Document 1 was designed as an imaging optical system for a single-lens reflex camera, and therefore has a long back focal length relative to its overall optical length. As a result, the overall optical length of this wide-angle zoom lens is too long for use as an imaging optical system for a single-lens non-reflex camera, and it cannot be said that it has been sufficiently compact and lightweight. As a result, the focus lens group is also insufficiently compact and lightweight.

[0007] Patent Document 2 also proposes a wide-angle zoom lens consisting of six groups (negative-positive-negative-positive-negative-positive) with the fifth lens group as a focus lens group. The wide-angle zoom lens disclosed in Patent Document 2 was designed as an imaging optical system for a single-lens non-reflex camera, and therefore has a short back focus relative to its overall optical length, and is small and lightweight. However, its zoom ratio is small, at around 2x, and it cannot be said that the size and weight are sufficiently reduced relative to the zoom ratio. Therefore, if an attempt is made to realize a zoom lens with a high zoom ratio, the overall size and weight will increase, as will the size and weight of the focus lens group. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4845993 [Patent Document 2] Patent No. 5699950 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a zoom lens and an imaging device that are compact and lightweight while providing high imaging performance throughout the entire zoom range. [Means for solving the problem]

[0010] In order to solve the above problems, the zoom lens of the present invention is composed of, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, and is a zoom lens in which the distance on the optical axis between adjacent lens groups changes during zooming, and is characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification at the telephoto end of the second lens group when focusing on infinity

[0011] In order to solve the above problem, the imaging device according to the present invention is characterized by including the zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a zoom lens and an imaging device that are compact and lightweight, while providing high imaging performance throughout the entire zoom range. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a lens cross-sectional view of a zoom lens according to a first embodiment of the present invention. [Figure 2] 4A and 4B are aberration diagrams of the zoom lens of Example 1 in the wide-angle end state. [Figure 3] 4A and 4B are aberration diagrams of the zoom lens of Example 1 in an intermediate focal length state. [Figure 4] 4A and 4B are aberration diagrams of the zoom lens of Example 1 in the telephoto end state. [Figure 5] FIG. 10 is a lens cross-sectional view of a zoom lens according to a second embodiment of the present invention. [Figure 6] 10A and 10B are aberration diagrams of the zoom lens of Example 2 in the wide-angle end state. [Figure 7] FIG. 10 is an aberration diagram of the zoom lens of Example 2 in the intermediate focal length state. [Figure 8] 10A and 10B are aberration diagrams of the zoom lens of Example 2 in the telephoto end state. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention. [Figure 10] 10A and 10B are aberration diagrams of the zoom lens of Example 3 in the wide-angle end state. [Figure 11] FIG. 10 is an aberration diagram of the zoom lens of Example 3 in the intermediate focal length state. [Figure 12] 10A and 10B are aberration diagrams of the zoom lens of Example 3 in the telephoto end state. [Figure 13] FIG. 10 is a lens cross-sectional view of a zoom lens according to a fourth embodiment of the present invention. [Figure 14] 10A and 10B are aberration diagrams of the zoom lens of Example 4 in the wide-angle end state. [Figure 15] 10A and 10B are aberration diagrams of the zoom lens of Example 4 in the intermediate focal length state. [Figure 16] 10A and 10B are aberration diagrams of the zoom lens of Example 4 in the telephoto end state. [Figure 17] FIG. 10 is a cross-sectional view of a zoom lens according to a fifth embodiment of the present invention. [Figure 18] 10A and 10B are aberration diagrams of the zoom lens of Example 5 in the wide-angle end state. [Figure 19] 10A and 10B are aberration diagrams of the zoom lens of Example 5 in the intermediate focal length state. [Figure 20] 10A and 10B are aberration diagrams of the zoom lens of Example 5 in the telephoto end state. DETAILED DESCRIPTION OF THE INVENTION

[0014] The following describes embodiments of the zoom lens and imaging device according to the present invention. However, the zoom lens and imaging device described below are one aspect of the optical system and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following aspects.

[0015] 1. Zoom Lens 1-1.Optical configuration The zoom lens is composed of, arranged in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, and the distance on the optical axis between adjacent lens groups changes during zooming.

[0016] The zoom lens employs a multi-group configuration of six or more groups, which facilitates suppressing aberration fluctuations during zooming and facilitates achieving high imaging performance regardless of the imaging distance. Furthermore, the zoom lens employs a first lens group with negative refractive power closest to the object, and a negative-lead type refractive power configuration facilitates achieving a zoom lens with a wide angle of view and a short back focus. These features facilitate achieving high imaging performance throughout the entire zoom range while achieving compactness and weight reduction. Furthermore, achieving overall compactness and weight reduction also enables the focus lens group to be made smaller and lighter, enabling rapid autofocus.

[0017] Although the specific lens configuration of each lens group is not particularly limited, it is preferable to adopt the following configuration, for example.

[0018] (1) First lens group The first lens group has negative refractive power and therefore includes one or more negative lenses. It is preferable that at least one of the negative lenses included in the first lens group is a meniscus lens with a concave shape facing the image side. By including a negative lens with such a lens shape, it is possible to provide the first lens group with strong negative refractive power while preventing off-axial light rays from being strongly bent as they pass through each surface of the first lens group. This reduces the occurrence of curvature of field and distortion, resulting in a zoom lens with excellent image surface characteristics. Furthermore, to improve image surface characteristics, it is preferable that at least one of the lenses in the first lens group has one or more aspherical surfaces. Furthermore, it is preferable that the first lens group includes at least one lens with positive refractive power in order to effectively correct various aberrations such as spherical aberration and coma.

[0019] (2) Second lens group The specific lens configuration of the second lens group is not particularly limited as long as it has positive refractive power. Since the second lens group has positive refractive power, it includes one or more positive lenses. If the second lens group includes two positive lenses, it is possible to provide the strong positive refractive power required to achieve a high zoom ratio in the second lens group, while suppressing field curvature and distortion, making it easy to achieve good imaging performance. In addition, spherical aberration can be suppressed by making the object-side surface convex. Furthermore, spherical aberration can be suppressed even more effectively by including a negative lens.

[0020] (3) Third lens group The specific lens configuration of the third lens group is not particularly limited as long as it has negative refractive power. Since the third lens group has negative refractive power, it has at least one negative lens. Furthermore, a configuration including at least one positive lens is preferable in terms of correcting various aberrations.

[0021] In this zoom lens, there is no particular limitation as to whether or not there is an image stabilization group, but for example, the third lens group may be composed of, from the object side, a 3a group having positive refractive power and a 3b group having negative refractive power, with the 3b group being movable in a direction perpendicular to the optical axis direction and used as an image stabilization group when vibrations such as camera shake occur. Note that even when the 3b group is used as an image stabilization group, the air gap between the 3a group and the 3b group does not change during zooming.

[0022] (4) Fourth lens group The fourth lens group is not particularly limited in its specific lens configuration, as long as it has positive refractive power. Since the fourth lens group has positive refractive power, it includes at least one positive lens. Furthermore, in order to ensure the refractive power required of the fourth lens group while suppressing the occurrence of various aberrations, such as spherical aberration, it is preferable for the fourth lens group to include two or more positive lenses, and it is also preferable for the fourth lens group to include one or more negative lenses. For example, by configuring the fourth lens group from the object side with a positive lens, a negative lens, a positive lens, and a negative lens, various aberrations, such as spherical aberration, can be effectively corrected, making it easier to realize a zoom lens with high imaging performance. Furthermore, by configuring the fourth lens group with multiple lenses in this way, it is possible to prevent the refractive power that each lens must bear from becoming too large, thereby reducing the effects of decentering errors during assembly.

[0023] It is also preferable that at least one of the lenses in the fourth lens group has one or more aspherical surfaces. In particular, it is preferable that the lens in the fourth lens group closest to the object has one or more aspherical surfaces. In this case, it is more preferable that the lens in the fourth lens group closest to the object is a positive lens, as described above. By providing an aspherical surface in the fourth lens group, various aberrations can be effectively corrected, and spherical aberration in particular can be effectively corrected.

[0024] (5) Fifth lens group The fifth lens group is not particularly limited in its specific lens configuration, as long as it has negative refractive power. Light beams converged by the fourth lens group, which has a positive refractive power, enter the fifth lens group. The fifth lens group is also located on the image plane side of the zoom lens. These features allow the height of light beams entering the fifth lens group to be kept low, thereby suppressing fluctuations in light beam height during zooming. Therefore, using the fifth lens group as a focus lens group facilitates the miniaturization and weight reduction of the focus lens group, making it easier to achieve rapid autofocus. Furthermore, because fluctuations in light beam height are small, using the fifth lens group as a focus lens group can suppress fluctuations in the angle of view even during wobbling, enabling excellent live view imaging and video capture.

[0025] Furthermore, if the fifth lens group is composed of only a single lens element having negative refractive power, when the fifth lens group is used as a focus lens group, the focus lens group can be made lighter and smaller, which is preferable for achieving fast autofocus. Note that a "single lens element" refers to an element composed of only one lens or a cemented lens formed by cementing multiple lenses together.

[0026] (6) Rear group In the zoom lens, the rear group has one or more lens groups. That is, the rear group may be composed of only one lens group, or may be composed of two or more lens groups. The rear group may have positive or negative refractive power as a whole. Therefore, each lens group constituting the rear group may have positive or negative refractive power. From the viewpoint of achieving a compact and lightweight zoom lens, it is preferable that the rear group be composed of one or two lens groups.

[0027] (7) Aperture diaphragm An aperture diaphragm is disposed within the zoom lens. The position of the aperture diaphragm in the zoom lens is not particularly limited, but it is preferably disposed, for example, between the image plane side of the first lens group and the object plane side of the rear lens group. In particular, it is preferably disposed closer to the image plane than the second lens group, more preferably closer to the object plane than the fifth lens group, and even more preferably closer to the object plane than the fourth lens group.

[0028] 1-2.Operation (1) Zooming The zoom lens changes magnification by changing the distance between adjacent lens groups on the optical axis during zooming. All lens groups may be moved along the optical axis during zooming, or some lens groups may be fixed along the optical axis while other lens groups are moved along the optical axis.

[0029] The presence or absence of movement of each lens group is not particularly limited, and the direction and amount of movement of each lens group can be set as appropriate. While the presence or absence, direction, and amount of movement may be different for all lens groups, it is preferable, for example, to designate the fourth lens group as the moving group and to make the amount of movement of the fourth lens group during zooming equal to the amount of movement of at least one of the lens groups arranged after the fifth lens group. The lens groups arranged after the fifth lens group refer to the sixth lens group when the rear group consists of one lens group, or to at least one of the lens groups included in the rear group when the rear group consists of two or more lens groups. This zoom lens employs a multi-group configuration of six or more groups. Therefore, if all lens groups were to move by different amounts depending on the imaging distance, the drive mechanism for driving each lens group would become complex, leading to an increase in the number of parts and an increase in the overall size. Furthermore, a complex drive mechanism or an increase in the number of parts would increase the likelihood of manufacturing errors, making it difficult to achieve the intended imaging performance. Therefore, if the fourth lens group and at least one of the lens groups arranged after the fifth lens group are moved by the same amount of movement, these lens groups can be mounted in the same lens frame and moved, which simplifies the drive mechanism and prevents an increase in the number of parts.This makes it easier to maintain a compact and lightweight overall structure while suppressing aberration fluctuations during zooming using a multi-group configuration.

[0030] (2) Focusing In this zoom lens, it is preferable to focus from infinity to an object at a finite distance by moving a lens group located closer to the image plane than the aperture diaphragm along the optical axis. By locating the focus lens group closer to the image plane than the aperture diaphragm in this way, fluctuations in the angle of view during wobbling can be suppressed. In particular, it is preferable to locate the aperture diaphragm closer to the object than the fifth lens group and to use the fifth lens group as the focus lens group, in order to suppress fluctuations in the angle of view during wobbling and to achieve a reduction in the size and weight of the focus lens group.

[0031] As described above, by configuring the fifth lens group from a single lens element, when the fifth lens group is used as a focus lens group, the focus lens group can be made smaller and lighter, which in turn allows for the drive mechanism, such as an actuator, that moves the focus lens group along the optical axis during focusing to be made smaller and lighter, thereby enabling the entire zoom lens to be made smaller and lighter. In particular, it is preferable that the focus lens group be composed of only one negative lens, in order to achieve even faster autofocusing and to make the zoom lens even smaller and lighter.

[0032] 1-3.Conditional Expressions It is preferable that the zoom lens satisfy one or more of the following conditions:

[0033] 1-3-1. Conditional Expression (1) (1) 6.05 ≦ β2t / β2w ≦ 15.00 however, β2w: Lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: Lateral magnification of the second lens group at the telephoto end when focusing on infinity

[0034] Conditional formula (1) defines the ratio between the lateral magnification of the second lens group at the wide-angle end when focusing on infinity and the lateral magnification of the second lens group at the telephoto end when focusing on infinity, and defines the variable magnification ratio provided by the second lens group during zooming. By satisfying conditional formula (1), it is possible to obtain a zoom lens with good imaging performance while ensuring a required predetermined zoom ratio. Furthermore, by satisfying conditional formula (1), the negative refractive power of the second lens group falls within an appropriate range, and degradation of imaging performance due to decentering errors during assembly, etc., can be suppressed.

[0035] On the other hand, if the value of conditional expression (1) falls below the lower limit, the negative refractive power of the second lens group becomes small, and in order to ensure the required zoom ratio, the amount of movement of the second lens group during zooming must be increased. This makes it difficult to achieve the required zoom ratio. Alternatively, the total optical length of the zoom lens increases, making it difficult to maintain the zoom lens compact. On the other hand, if the value of conditional expression (1) exceeds the upper limit, the negative refractive power of the second lens group becomes too large, which increases the impact on imaging performance due to decentering errors during assembly, and increases the difficulty in manufacturing to achieve the designed imaging performance, which is undesirable.

[0036] To obtain the above effects, the lower limit of conditional formula (1) is more preferably 6.17, and even more preferably 6.50. The upper limit of conditional formula (1) is more preferably 13.00, and even more preferably 10.00. When adopting these preferred values, the inequality sign with an equal sign (≦) in conditional formula (1) may be replaced with an inequality sign (<). The same applies to other conditional formulas; when other conditional formulas are expressed with inequality signs, the inequality sign may be replaced with an inequality sign with an equal sign.

[0037] 1-3-2. Conditional Expression (2) In the zoom lens, when the third lens group is composed of, in order from the object side as described above, a 3a group having positive refractive power and a 3b group having negative refractive power, and the 3b group is used as an image stabilization group, it is preferable that the following conditional expression (2) be satisfied: (2) 0.28 < f3B / f3 < 1.35 however, f3B: focal length of the 3bth group f3: focal length of the third lens group

[0038] Conditional formula (2) above defines the ratio between the focal length of the 3b lens group and the focal length of the third lens group. By satisfying conditional formula (2), the refractive power of the 3b lens group, which serves as the image stabilization group, falls within an appropriate range. Therefore, when the 3b lens group is moved perpendicular to the optical axis during image stabilization, i.e., when the 3b lens group is decentered, the occurrence of decentering coma and decentering astigmatism can be suppressed, thereby preventing deterioration of imaging performance during image stabilization. Furthermore, because the amount of movement of the 3b lens group during image stabilization can be kept within an appropriate range, the load on the image stabilization drive mechanism can be reduced, allowing for a more compact and lightweight image stabilization drive mechanism. Therefore, even when the zoom lens is provided with image stabilization functionality, the zoom lens can be kept small and lightweight while maintaining good imaging performance during image stabilization.

[0039] On the other hand, if the value of conditional expression (2) is below the lower limit, the refractive power of the 3b lens group becomes too strong, and decentering coma and astigmatism that occur when the 3b lens group is decentered become large, which is undesirable as it leads to a deterioration in imaging performance during image stabilization. On the other hand, if the value of conditional expression (2) is above the upper limit, the negative refractive power of the 3b lens group becomes too weak, and the amount of movement of the 3b lens group during image stabilization becomes large. As a result, the load on the image stabilization drive mechanism becomes large, which leads to an increase in the size of the image stabilization drive mechanism and makes it difficult to reduce the size of the entire zoom lens, including the lens barrel, which is undesirable.

[0040] To obtain the above effect, the lower limit of conditional expression (2) is more preferably 0.29, and even more preferably 0.30, and the upper limit of conditional expression (2) is more preferably 1.17, and even more preferably 0.90.

[0041] 1-3-3. Conditional Expression (3) In the zoom lens, when the lens group arranged on the image plane side of the aperture stop is the focus lens group, it is preferable that the following conditional expression (3) be satisfied. (3) 0.25 < Dwif / Dw < 0.44 however, Dwif: The distance on the optical axis between the aperture stop and the focus lens group when focusing at infinity at the wide-angle end Dw: Total optical length of the zoom lens at the wide-angle end

[0042] The above conditional expression (3) defines the positional relationship between the aperture stop and the focus lens group when focusing on infinity at the wide-angle end. By satisfying conditional expression (3), fluctuations in the angle of view during wobbling can be suppressed, enabling good live view imaging and video capture. Note that the total optical length refers to the distance on the optical axis from the vertex of the surface of the optical system closest to the object to the image plane.

[0043] On the other hand, if the value of conditional expression (3) is equal to or less than the lower limit, fluctuations in the angle of view during wobbling become large, which may cause unnatural images during live view imaging or video capture, which is undesirable.On the other hand, if the value of conditional expression (3) is equal to or greater than the upper limit, it will undesirably result in an increase in the size of the lens group located closer to the image plane than the aperture stop.

[0044] To obtain the above effect, the lower limit of conditional expression (3) should preferably be 0.26, and more preferably be 0.27, and the upper limit of conditional expression (3) should preferably be 0.38, and even more preferably be 0.29.

[0045] 1-3-4. Conditional Expressions (4) and (5) In the zoom lens, when the focus lens group is made up of only one negative lens, it is preferable that the following conditional expressions (4) and (5) be satisfied. (4) nd > 1.83 (5) νd > 30 however, nd: refractive index of the negative lens at the d line νd: Abbe number at the d line of the negative lens

[0046] The above conditional formula (4) defines the refractive index at the d-line of the negative lens that constitutes the focus lens group, and the above conditional formula (5) defines the Abbe number at the d-line of the negative lens that constitutes the focus lens group. By configuring the focus lens group with negative lenses that satisfy conditional formulas (4) and (5), it becomes possible to suppress chromatic aberration while ensuring sufficient refractive power in the focus lens group. As a result, it is possible to keep the amount of movement of the focus lens group small during focusing, suppress an increase in the number of lenses required for chromatic aberration correction, and facilitate the realization of good imaging performance while achieving a compact and lightweight zoom lens.

[0047] On the other hand, if the value of conditional expression (4) is below the lower limit, the refractive power of the focus lens group will be weak, and if the focus lens group is configured with this one negative lens, the amount of movement during focusing will need to be large. This is undesirable because it increases the overall optical length or makes it difficult to configure the focus lens group with only one negative lens. Furthermore, if the value of conditional expression (5) is below the lower limit, chromatic dispersion will increase, making it difficult to suppress chromatic aberration. This is undesirable because it will require a configuration that includes a positive lens to correct chromatic aberration, making it difficult to configure the focus lens group with only one negative lens.

[0048] In order to obtain the above effects, the lower limit of conditional expression (4) should preferably be 1.85, and more preferably be 1.87. The lower limit of conditional expression (5) should preferably be 32, and even more preferably be 37.

[0049] 2. Imaging device Next, we will explain the imaging device of the present invention. The imaging device of the present invention is characterized by including the imaging lens of the present invention described above and an imaging element that converts an optical image formed by the imaging lens into an electrical signal. It is preferable that the imaging element is provided on the image side of the optical system.

[0050] Here, the imaging element is not particularly limited, and solid-state imaging elements such as a CCD (Charge Coupled Device) sensor or 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 such solid-state imaging elements, such as digital cameras and video cameras. The imaging device can also be applied to various imaging devices, such as single-lens reflex cameras, mirrorless single-lens cameras, digital still cameras, surveillance cameras, in-vehicle cameras, and drone-mounted cameras. These imaging devices may be interchangeable lens imaging devices, or fixed lens imaging devices in which the lens is fixed to the housing.

[0051] Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples. [Example]

[0052] (1) Optical configuration 1 is a cross-sectional view of a zoom lens according to Example 1 of the present invention, with the upper diagram showing the wide-angle end state (W), the middle diagram showing the intermediate focal length state (M), and the lower diagram showing the telephoto end state (T). Since the cross-sectional views of the lenses shown in each Example are the same, a description thereof will be omitted below.

[0053] 1, the zoom lens includes, from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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. An aperture stop SP is located on the object side of the third lens group G3.

[0054] Specifically, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, a biconcave lens, and a biconvex lens.

[0055] The second lens group G2 is composed of, in order from the object side, a biconvex lens and a cemented lens in which a biconvex lens and a biconcave lens are cemented together.

[0056] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens with a convex surface facing the object side, and a concave-plano lens with a concave surface facing the object side.

[0057] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens with its convex surface facing the object side, and a cemented lens formed by cementing together three lenses: a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0058] The fifth lens group G5 is composed of a biconcave lens.

[0059] The sixth lens group G6 is composed of a biconvex lens and a biconcave lens.

[0060] In this zoom lens, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a convex path toward the image plane, and the second lens group G2 to the sixth lens group G6 each move toward the object. At that time, the fourth lens group G4 and the sixth lens group G6 move toward the object by the same amount. In addition, in this zoom lens, the fifth lens group G5 is a focus lens group, and focusing from infinity to an object at a finite distance is performed by moving the fifth lens group G5 toward the image plane along the optical axis.

[0061] (2) Numerical examples Next, a numerical example of the optical system will be described. The surface data, aspherical surface data, various data, and variable intervals of the optical system are shown below. In the (Surface Data) section, "Surface No." indicates the order of the lens surface counted from the object side (surface number), "r" indicates the radius of curvature of the lens surface, "d" indicates the spacing on the optical axis of the lens surface, "Nd" indicates the refractive index for the d-line (wavelength λ=587.6 nm), and "νd" indicates the Abbe number for the d-line. In the "Surface No." column, an "*" next to the surface number indicates that the surface is aspherical, and "SP" indicates that the surface is the aperture stop SP. In the "d" column, "D○○" (e.g., D9 in this embodiment) indicates a variable spacing during zooming. In the following numerical examples, all length units are "mm," and all angle of view units are "°." In the numerical examples, "∞" indicates infinity.

[0062] (Aspherical surface data) indicates the aspherical coefficients of each aspherical surface. Note that the aspherical surface is defined by the following equation, where x is the amount of displacement from the vertex of the surface in the optical axis direction. x=(h 2 / r) / [1+{1-(1+K)×(h / r) 2} 1 / 2 )] +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 In the above formula, h is the height from the optical axis, r is the paraxial radius of curvature, K is the conic coefficient, and An is the n-th order aspheric coefficient. Also, "E±XX" represents exponential notation, and is expressed as "×10 ±XX " means.

[0063] In (various data), the zoom ratio represents the ratio of the focal length at the telephoto end of the zoom lens to the focal length at the wide-angle end, and the focal length, F-number, angle of view, image height, total optical length, and BF (back focus) represent the values ​​at the wide-angle end, mid-focal length, and telephoto end, respectively.

[0064] (Variable Distance) shows the variable distances at the wide-angle end, mid-focal length, and telephoto end.

[0065] Furthermore, the values ​​of the conditional expressions (1) to (5) are shown in Table 1 (discussed later). The matters relating to these numerical examples are similar to the numerical examples shown in the other examples, and therefore will not be described below.

[0066] FIGS. 2, 3, and 4 show longitudinal aberration diagrams of the zoom lens when focused at infinity in the wide-angle end state, the mid-focal length state, and the telephoto end state. Each longitudinal aberration diagram, from left to right, shows spherical aberration, astigmatism, and distortion. In the diagrams showing spherical aberration, the vertical axis shows the ratio to the maximum aperture (FNO.) and the horizontal axis shows defocus (mm), indicating spherical aberration at the d-line (wavelength λ=587.56 nm). In the diagrams showing astigmatism, the vertical axis shows half angle of view (ω) and the horizontal axis shows defocus (mm), with the solid line indicating the sagittal image plane (S) relative to the d-line and the dotted line indicating the meridional image plane (M) relative to the d-line. In the diagrams showing distortion, the vertical axis shows half angle of view (ω) and the horizontal axis shows distortion (%). The details of these diagrams are the same as those of the longitudinal aberration diagrams shown in other embodiments, so further explanation will be omitted below.

[0067] (surface data) Surface No. rd Nd νd 1 116.662 1.500 1.900 37.372 2 22.255 7.287 3 125.511 1.500 1.589 61.252 4 42.479 0.150 1.515 49.963 5* 34.738 7.483 6 -58.107 1.500 1.497 81.607 7 36.299 0.300 8 36.657 6.331 1.750 35.332 9 -98.710 (D9) 10 250.808 3.271 1.517 64.197 11 -39.893 0.150 12 30.971 5.064 1.497 81.607 13 -46.946 1.000 1.911 35.249 14 238.287 (D14) 15SP ∞ 1.000 16 70.422 2.427 1.923 20.880 17 96925.576 2.693 18* -32.894 1.000 1.851 40.104 19* ∞ (D19) 20* 36.888 5.947 1.851 40.104 21* -33.900 0.162 22 119.269 0.900 1.905 35.036 23 17.848 9.876 1.497 81.607 24 -15.385 1.000 2.001 25.458 25 -21.416 (D25) 26 -8321.643 0.800 1.881 40.138 27 31.452 (D27) 28 230.024 3.136 1.808 22.760 29 -60.347 0.300 30 -457.051 1.200 1.835 42.721 31 42.221 (D31) Image plane ∞

[0068] (Aspheric surface) Noodle No. K A4 A6 A8 A10 A12 5 0.00000 -8.35908E-06 -1.48501E-08 2.14604E-11 2.70591E-14 -1.68907E-16 18 0.00000 -2.23588E-05 7.43485E-08 -9.71180E-11 7.50728E-13 -8.81094E-15 19 0.00000 -3.20168E-05 1.29894E-07 -7.34265E-10 4.83003E-12 -2.17461E-14 20 0.00000 -5.01801E-06 1.04674E-07 2.59949E-10 -1.61574E-12 1.96338E-14 21 0.00000 3.01366E-05 2.27937E-08 1.05286E-09 -8.29506E-12 5.14222E-14

[0069] (Various data) Zoom ratio 2.767 Focal length 17.520 29.114 48.483 F-number 4.120 4.120 4.120 Angle of view 110.747 71.937 47.366 Image height 21.633 21.633 21.633 Optical total length 134.456 133.533 134.456 BF 18.462 27.816 50.815

[0070] (variable interval) Focal length 17.520 29.114 48.483 D9 30.694 13.079 1.000 D14 1.588 16.382 8.584 D19 10.720 3.263 1.065 D25 2.087 2.159 2.005 D27 4.926 4.855 5.009 D31 18.462 27.816 50.815 [Example]

[0071] (1) Optical configuration Figure 5 is a cross-sectional view of a zoom lens according to Example 2 of the present invention. As shown in Figure 5, the zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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. An aperture stop SP is located on the object side of the third lens group.

[0072] Specifically, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, a biconcave lens, and a biconvex lens.

[0073] The second lens group G2 is composed of, in order from the object side, a biconvex lens and a cemented lens in which a biconvex lens and a biconcave lens are cemented together.

[0074] The third lens group G3 is composed of, in order from the object side, a biconvex lens and a concave-plano lens with its concave surface facing the object side.

[0075] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens with its convex surface facing the object side, and a cemented lens formed by cementing together three lenses: a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0076] The fifth lens group G5 is composed of a biconcave lens.

[0077] The sixth lens group G6 is composed of a biconvex lens and a biconcave lens.

[0078] In this zoom lens, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a convex path toward the image plane, and the second lens group G2 to the sixth lens group G6 each move toward the object. At that time, the fourth lens group G4 and the sixth lens group G6 move toward the object by the same amount. In addition, in this zoom lens, the fifth lens group G5 is a focus lens group, and focusing from infinity to an object at a finite distance is performed by moving the fifth lens group G5 toward the image plane along the optical axis.

[0079] (2) Numerical examples Next, a numerical example of the zoom lens will be described. The surface data, aspherical surface data, various data, and variable interval data of the zoom lens are shown below.

[0080] 6, 7 and 8 show longitudinal aberration diagrams of the zoom lens when focused on infinity in the wide-angle end state, the intermediate focal length state and the telephoto end state.

[0081] (surface data) Surface No. rd Nd νd 1 122.190 1.500 1.900 37.372 2 22.553 7.539 3 164.876 1.500 1.589 61.252 4 43.515 0.150 1.515 49.963 5* 35.422 7.553 6 -61.782 1.500 1.497 81.607 7 36.974 0.300 8 37.345 6.388 1.750 35.332 9 -97.540 (D9) 10 158.314 3.433 1.517 64.197 11 -40.854 0.150 12 30.050 5.178 1.497 81.607 13 -47.703 1.000 1.911 35.249 14 187.128 (D14) 15SP ∞ 1.000 16 82.239 2.469 1.923 20.880 17 -347.090 2.541 18* -30.431 1.000 1.851 40.104 19* ∞ (D19) 20* 35.817 5.965 1.851 40.104 21* -33.819 0.100 22 115.184 0.900 1.905 35.036 23 17.641 9.860 1.497 81.607 24 -15.385 1.000 2.001 25.458 25 -21.393 (D25) 26 -655.514 0.800 1.881 40.138 27 31.675 (D27) 28 389.512 3.095 1.808 22.760 29 -56.426 0.300 30 -894.549 1.200 1.835 42.721 31 43.209 (D31) Image plane ∞

[0082] (Aspheric surface) Noodle No. K A4 A6 A8 A10 A12 5 0.00000 -8.49948E-06 -1.39065E-08 2.71461E-11 -2.84477E-15 -1.13437E-16 18 0.00000 -1.08768E-05 1.42275E-08 2.34536E-10 4.42543E-14 -8.81094E-15 19 0.00000 -2.18182E-05 5.84966E-08 -2.67964E-10 3.37438E-12 -2.17461E-14 20 0.00000 -3.21034E-06 1.03186E-07 3.79315E-10 -1.57233E-12 1.96337E-14 21 0.00000 3.29171E-05 2.87556E-08 1.03088E-09 -7.14554E-12 5.14222E-14

[0083] (Specifications) Zoom ratio 2.767 Focal length 17.521 29.120 48.481 F-number 4.120 4.120 4.120 Angle of view 110.742 71.975 47.354 Image height 21.633 21.633 21.633 Optical total length 134.497 132.478 134.497 BF 18.324 27.660 50.655

[0084] (variable interval) Focal length 17.521 29.120 48.481 D9 30.396 12.940 1.000 D14 1.617 14.823 8.249 D19 10.599 3.495 1.031 D25 2.168 2.138 2.005 D27 4.972 5.002 5.135 D31 18.324 27.660 50.655 [Example]

[0085] (1) Optical configuration Figure 9 is a cross-sectional view of a zoom lens according to a third embodiment of the present invention. As shown in Figure 9, the zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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. An aperture stop SP is located on the object side of the third lens group.

[0086] Specifically, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, and a cemented lens formed by cementing together a biconcave lens and a biconvex lens.

[0087] The second lens group G2 is composed of, in order from the object side, a positive meniscus lens with its concave surface facing the object side, and a cemented lens in which a biconvex lens and a biconcave lens are cemented together.

[0088] The third lens group G3 is composed of, from the object side, a group 3a with positive refractive power and a group 3b with negative refractive power. Group 3a is composed of a positive meniscus lens with its convex surface facing the object side. Group 3b is composed of a cemented lens consisting of a biconcave lens and a biconvex lens.

[0089] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens with its convex surface facing the object side, and a cemented lens formed by cementing together three lenses: a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0090] The fifth lens group G5 is composed of a negative meniscus lens with its convex surface facing the object side.

[0091] The sixth lens group G6 is composed of a biconvex lens and a biconcave lens.

[0092] In this zoom lens, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a convex path toward the image plane, and the second to sixth lens groups G2 to G6 each move toward the object. At that time, the fourth lens group G4 and the sixth lens group G6 move toward the object by the same amount. In this zoom lens, the fifth lens group G5 is a focus lens group, and focusing from infinity to an object at a finite distance is achieved by moving the fifth lens group G5 toward the image plane along the optical axis. In this zoom lens, the 3b group is configured to be movable perpendicular to the optical axis and functions as an image stabilization group VC.

[0093] (2) Numerical examples Next, a numerical example of the zoom lens will be described. The surface data, aspherical surface data, various data, and variable interval data of the zoom lens are shown below.

[0094] 10, 11 and 12 show longitudinal aberration diagrams of the zoom lens when focused on infinity in the wide-angle end state, the intermediate focal length state and the telephoto end state.

[0095] (surface data) Surface No. rd Nd νd 1 88.560 1.500 1.881 40.138 2 19.158 8.350 3 202.429 1.750 1.497 81.607 4 40.577 0.150 1.536 41.207 5* 31.862 6.437 6 -130.488 1.510 1.497 81.607 7 29.564 5.527 1.750 35.332 8 -197.722 (D8) 9 -428.459 2.750 1.673 32.099 10 -41.705 0.150 11 24.729 6.687 1.497 81.607 12 -36.641 1.000 1.855 24.799 13 182.449 (D13) 14SP∞1.113 15 47.106 1.787 1.850 30.046 16 52.050 2.908 17* -50.678 1.200 1.882 37.221 18 31.198 3.351 1.808 22.764 19 -444.033 (D19) 20* 29.959 5.269 1.851 40.104 21* -46.453 0.100 22 51.709 0.900 1.905 35.047 23 15.431 10.473 1.497 81.607 24 -15.385 1.000 2.001 25.458 25 -22.483 (D25) 26 439.664 0.800 1.881 40.138 27 28.474 (D27) 28 113.580 3.005 1.923 20.880 29 -89.615 0.100 30 -163.142 1.200 1.871 40.744 31 47.217 (D31) Image plane ∞

[0096] (aspheric data) Surface No. Κ A4 A6 A8 A10 A12 5 0.00000 -1.19398E-05 -1.10752E-09 -1.54010E-10 5.81099E-13 -1.08575E-15 17 0.00000 5.47310E-06 -6.69571E-09 -5.83936E-11 8.47422E-13 -2.65483E-15 20 0.00000 -7.54991E-06 2.77768E-08 -6.99811E-11 -2.17135E-14 0.00000E+00 21 0.00000 1.89851E-05 -1.51570E-08 -5.20330E-12 -1.14685E-13 0.00000E+00

[0097] (Specifications) Zoom ratio 2.767 Focal length 17.524 29.093 48.479 F-number 4.120 4.120 4.120 Angle of view 110.761 74.502 47.796 Image height 21.633 21.633 21.633 Optical total length 131.927 124.228 131.927 BF 18.590 31.102 53.306

[0098] (variable interval) Focal length 17.524 29.093 48.479 D8 27.912 10.970 1.000 D13 2.582 4.268 1.870 D19 8.092 3.138 1.000 D25 0.990 1.046 1.013 D27 4.744 4.687 4.720 D31 18.590 31.102 53.306 [Example]

[0099] (1) Optical configuration Figure 13 is a cross-sectional view of a zoom lens according to a fourth embodiment of the present invention. As shown in Figure 13, the zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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. An aperture stop SP is located on the object side of the third lens group.

[0100] Specifically, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, and a cemented lens formed by cementing together a biconcave lens and a positive meniscus lens with a convex surface facing the object side.

[0101] The second lens group G2 is composed of, in order from the object side, a positive meniscus lens with a concave surface facing the object side, and a cemented lens formed by cementing together a biconvex lens and a negative meniscus lens with a concave surface facing the object side.

[0102] The third lens group G3 is composed of, from the object side, a group 3a having positive refractive power and a group 3b having negative refractive power. The group 3a is composed of a positive meniscus lens with its convex surface facing the object side. The group 3b is composed of a cemented lens consisting of a biconcave lens and a positive meniscus lens with its convex surface facing the object side.

[0103] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens with its convex surface facing the object side, and a cemented lens formed by cementing together three lenses: a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0104] The fifth lens group G5 is composed of a negative meniscus lens with its convex surface facing the object side.

[0105] The sixth lens group G6 is composed of a biconvex lens and a biconcave lens.

[0106] In this zoom lens, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves along a convex path toward the image plane, and the second to sixth lens groups G2 to G6 each move toward the object. At that time, the fourth lens group G4 and the sixth lens group G6 move toward the object by the same amount. In this zoom lens, the fifth lens group G5 is a focus lens group, and focusing from infinity to an object at a finite distance is achieved by moving the fifth lens group G5 toward the image plane along the optical axis. In this zoom lens, the 3b group is configured to be movable perpendicular to the optical axis and functions as an image stabilization group VC.

[0107] (2) Numerical examples Next, a numerical example of the zoom lens will be described. The surface data, aspherical surface data, various data, and variable interval data of the zoom lens are shown below.

[0108] 14, 15 and 16 show longitudinal aberration diagrams of the zoom lens when focused on infinity in the wide-angle end state, the intermediate focal length state and the telephoto end state.

[0109] (surface data) Surface No. rd Nd νd 1 114.979 1.500 1.881 40.138 2 20.742 5.306 3 40.818 1.750 1.497 81.607 4 28.571 0.150 1.536 41.207 5* 23.179 10.536 6 -169.114 1.510 1.497 81.607 7 27.504 5.016 1.750 35.332 8 629.103 (D8) 9 -67.550 2.750 1.673 32.099 10 -33.351 0.150 11 33.570 6.145 1.497 81.607 12 -35.508 1.000 1.855 24.799 13 -174.454 (D13) 14SP ∞ 1.216 15 39.048 3.244 1.850 30.046 16 211.203 2.336 17* -40.091 1.200 1.882 37.221 18 36.434 2.345 1.808 22.764 19 124.943 (D19) 20* 34.601 4.820 1.851 40.104 21* -51.530 0.100 22 47.586 0.900 1.905 35.047 23 14.618 10.273 1.497 81.607 24 -15.385 1.000 2.001 25.458 25 -22.501 (D25) 26 187.347 0.800 1.881 40.138 27 27.588 (D27) 28 111.335 3.050 1.923 20.880 29 -87.318 0.100 30 -162.558 1.200 1.871 40.744 31 49.650 (D31) Image plane ∞

[0110] (Aspheric surface) Noodle No. K A4 A6 A8 A10 A12 5 0.00000 -1.29756E-05 -1.21587E-08 -1.25616E-10 4.19080E-13 -8.30275E-16 17 0.00000 9.69098E-06 2.10582E-08 -2.90183E-10 1.62250E-12 -3.55012E-15 20 0.00000 3.30964E-06 3.34192E-09 8.68898E-11 -5.60914E-13 0.00000E+00 21 0.00000 2.56252E-05 -2.23895E-08 3.72866E-12 -3.42994E-13 0.00000E+00

[0111] (Specifications) Zoom ratio 2.766 Focal length 17.529 29.104 48.479 F-number 4.120 4.120 4.120 Angle of view 110.806 72.896 47.493 Image height 21.633 21.633 21.633 Optical total length 134.520 130.515 134.520 BF 18.643 29.793 52.873

[0112] (variable interval) Focal length 17.529 29.104 48.479 D8 30.892 13.243 2.132 D13 1.200 9.893 4.161 D19 9.431 3.232 1.000 D25 0.981 0.999 1.006 D27 4.976 4.957 4.951 D31 18.643 29.793 52.873 [Example]

[0113] (1) Optical configuration Fig. 17 is a cross-sectional view of a zoom lens according to a fifth embodiment of the present invention. As shown in Fig. 17, the zoom lens includes, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. An aperture stop SP is located on the object side of the third lens group.

[0114] Specifically, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, a biconcave lens, and a biconvex lens.

[0115] The second lens group G2 is composed of, in order from the object side, a biconvex lens and a cemented lens formed by cementing together a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0116] The third lens group G3 is composed of, in order from the object side, a plano-convex lens with a flat surface facing the object side, and a concave-plano lens with a concave surface facing the object side.

[0117] The fourth lens group G4 is composed of, in order from the object side, a biconvex lens, a negative meniscus lens with its convex surface facing the object side, and a cemented lens formed by cementing together three lenses: a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0118] The fifth lens group G5 is composed of a negative meniscus lens with its convex surface facing the object side.

[0119] The sixth lens group G6 is composed of a biconvex lens and a negative meniscus lens with its concave surface facing the object side.

[0120] The seventh lens group G7 is composed of a biconcave lens.

[0121] In this zoom lens, when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in a convex path toward the image plane, the second lens group G2 to the sixth lens group G6 each move toward the object plane, and the seventh lens group G7 is fixed in the optical axis direction. At that time, the fourth lens group G4 and the sixth lens group G6 move toward the object plane by the same amount. In this zoom lens, the fifth lens group G5 is a focus lens group, and focusing from infinity to a finite distance object is achieved by moving the fifth lens group toward the image plane along the optical axis.

[0122] (2) Numerical examples Next, a numerical example of the zoom lens will be described. The surface data, aspherical surface data, various data, and variable interval data of the zoom lens are shown below.

[0123] 18, 19 and 20 show longitudinal aberration diagrams of the zoom lens when focused on infinity in the wide-angle end state, the intermediate focal length state and the telephoto end state.

[0124] (surface data) Surface No. rd Nd νd 1 93.705 1.500 1.900 37.372 2 23.164 6.452 3 105.606 1.500 1.589 61.252 4 31.484 0.150 1.515 49.963 5* 26.768 7.204 6 -63.204 1.500 1.497 81.607 7 37.051 0.300 8 36.738 5.448 1.750 35.332 9 -133.368 (D9) 10 56.387 3.947 1.517 64.197 11 -41.149 0.150 12 45.255 4.469 1.497 81.607 13 -34.708 1.000 1.911 35.249 14 -733.604 (D14) 15SP∞1.000 16 ∞ 2.642 1.923 20.880 17 -51.384 2.061 18* -22.797 1.000 1.851 40.104 19*∞ (D19) 20* 29.045 5.627 1.851 40.104 21* -32.899 0.100 22 204.332 0.900 1.905 35.036 23 15.616 10.489 1.497 81.607 24 -15.385 1.000 2.001 25.458 25 -21.552 (D25) 26 166.252 0.800 1.881 40.138 27 27.647 (D27) 28 119.930 3.480 1.808 22.760 29 -56.608 0.300 30 -60.219 1.200 1.835 42.721 31 -9609.655 (D31) 32 -10000.003 0.950 1.755 27.512 33 72.488 19.219 Image plane ∞

[0125] (aspheric data) Surface No. Κ A4 A6 A8 A10 A12 5 0.00000 -1.08858E-05 -1.79866E-08 4.17985E-11 -2.22629E-14 -1.14401E-16 18 0.00000 -3.95092E-05 7.10557E-07 -6.04300E-09 2.28934E-11 -8.81094E-15 19 0.00000 -5.57906E-05 7.02750E-07 -6.09063E-09 2.45401E-11 -2.17461E-14 20 0.00000 -8.01562E-06 6.99384E-09 1.20370E-09 -1.38755E-11 5.88224E-14 21 0.00000 3.08260E-05 -4.40833E-08 1.05042E-09 -1.16373E-11 5.14222E-14

[0126] (Specifications) Zoom ratio 2.767 Focal length 17.525 29.144 48.493 F-number 4.120 4.120 4.120 Angle of view 110.717 71.408 46.937 Image height 21.633 21.633 21.633 Optical total length 136.148 130.882 136.148 BF 19.219 19.219 19.219

[0127] (variable interval) Focal length 17.525 29.144 48.493 D9 31.232 12.302 1.000 D14 1.471 12.971 12.863 D19 11.139 5.058 1.000 D25 1.985 2.580 2.003 D27 4.932 4.337 4.915 D31 1.000 9.244 29.979

[0128] [Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 (1)β2t / β2w 10.00 6.50 6.50 7.01 10.00 (2) f3B / f3 - - 0.87 0.33 - (3)Dwif / Dw 0.281 0.280 0.282 0.281 0.279 (4)nd 1.881 1.881 1.881 1.881 1.881 (5)νd 40.138 40.138 40.138 40.138 40.138 [Industrial Applicability]

[0129] According to the present invention, it is possible to provide a zoom lens and an imaging device that are compact and lightweight, while providing high imaging performance throughout the entire zoom range.

Claims

1. A zoom lens comprising, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, wherein the spacing between adjacent lens groups changes during zooming, the fourth lens group is composed of a positive lens, a negative lens, a positive lens, and a negative lens, which are arranged in this order from the object side, A zoom lens characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification of the second lens group at the telephoto end when focused on infinity

2. A zoom lens comprising, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, wherein the spacing between adjacent lens groups changes during zooming, the third lens group is composed of, in order from the object side, a third-a group having positive refractive power and a third-b group having negative refractive power; the 3b group is configured to be movable in a direction perpendicular to the optical axis, A zoom lens characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 (2) 0.28 < f3B / f3 < 1.35 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification of the second lens group at the telephoto end when focused on infinity f3B: focal length of the 3b lens group f3: focal length of the third lens group

3. A zoom lens comprising, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, wherein the spacing between adjacent lens groups changes during zooming, The zoom lens has an aperture stop therein, a focus lens group that moves along the optical axis when focusing from infinity to a finite distance object, on the image plane side of the aperture stop; the focus lens group is composed of only one negative lens, A zoom lens characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 (4) nd > 1.83 (5) νd>30 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification of the second lens group at the telephoto end when focused on infinity nd: refractive index at the d line of the negative lens constituting the focus lens group νd: Abbe number at the d-line of the negative lens constituting the focus lens group

4. A zoom lens comprising, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, wherein the spacing between adjacent lens groups changes during zooming, During zooming, the amount of movement of the fourth lens group is equal to the amount of movement of at least one of the lens groups included in the rear group, the fifth lens group is a focus lens group that moves when focusing from infinity to a finite distance object, A zoom lens characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification of the second lens group at the telephoto end when focused on infinity

5. A zoom lens comprising, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a rear group having one or more lens groups, wherein the spacing between adjacent lens groups changes during zooming, During zooming, the amount of movement of the fourth lens group is equal to the amount of movement of at least one of the lens groups included in the rear group, The zoom lens has an aperture stop therein, a focus lens group that moves along the optical axis when focusing from infinity to a finite distance object, on the image plane side of the aperture stop; A zoom lens characterized by satisfying the following conditional expression: (1) 6.05 ≦ β2t / β2w ≦ 15.00 however, β2w: lateral magnification of the second lens group at the wide-angle end when focusing on infinity β2t: lateral magnification of the second lens group at the telephoto end when focused on infinity

6. 2. The zoom lens according to claim 1, wherein the positive lens arranged closest to the object in the fourth lens group has an aspherical surface.

7. 6. The zoom lens according to claim 3, wherein the focus lens group satisfies the following condition: (3) 0.25<Dwif / Dw<0.44 however, Dwif: the distance on the optical axis between the aperture stop and the focus lens group when focusing on infinity at the wide-angle end Dw: total optical length of the zoom lens at the wide-angle end

8. 8. An imaging device comprising: the zoom lens according to claim 1; and an imaging element that converts an optical image formed by the zoom lens into an electrical signal.

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