Zoom lens and image pickup apparatus

Abstract

The problem is to achieve a zoom lens and an imaging device that can achieve both miniaturization and high performance. The solution is that the zoom lens is composed of a positive first lens group, a negative second lens group, an n-th lens group including one or more lens groups, a negative (n+1)-th lens group, a positive (n+2)-th lens group, and a negative (n+3)-th lens group in order from the object side, the first lens group is fixed in the optical axis direction during zooming, and the zoom lens satisfies two specific equations related to the (n+2)-th lens group and the (n+3)-th lens group.

Description

Technical Field

[0001] This invention relates to zoom lenses and imaging devices. Background Technology

[0002] In the field of imaging devices, various devices such as mirrorless single-lens cameras, digital cameras, and security cameras are known, and imaging devices with sufficiently high performance are widely available on the market. Among the zoom lenses used to display optical performance in such conventional imaging devices, zoom lenses with seven lens groups, each comprising a lens group with an optical power of positive, negative, positive, positive, negative, positive, and negative from the object side, are known (see, for example, Patent Documents 1-3).

[0003] Prior art literature Patent documents Patent Document 1: Japanese Patent Application Publication No. 2020-086133 Patent Document 2: Japanese Patent Application Publication No. 2022-103302 Patent Document 3: Japanese Patent Application Publication No. 2022-067732 Summary of the Invention The problem that the invention aims to solve On the other hand, there is still room for discussion regarding the balance between high performance and convenience in conventional zoom lenses. For example, in the zoom lens of Patent Document 1, the first lens group is fixed, and the overall length of the zoom lens is fixed, while the total thickness of the other lens groups is large, sometimes making it difficult to shorten the overall length of the zoom lens. Furthermore, in the zoom lens of Patent Document 2, the first lens group is fixed, and the overall length of the zoom lens is fixed, but due to the relationship between the optical power of the other lens groups, it is sometimes difficult to achieve sufficient aberration correction. Additionally, in the zoom lens of Patent Document 3, the first lens group moves along the optical axis, thus requiring a corresponding sliding mechanism, sometimes making it difficult to achieve radial miniaturization.

[0004] One objective of the present invention is to realize a zoom lens and camera device that can achieve both miniaturization and high performance.

[0005] Methods for solving problems To address the aforementioned issues, one aspect of the present invention relates to a zoom lens comprising, from the object side, a first lens group having positive optical power, a second lens group having negative optical power, an nth lens group including one or more lens groups, an (n+1)th lens group having negative optical power, an (n+2)th lens group having positive optical power, and an (n+3)th lens group having negative optical power. During zooming, the first lens group is fixed in the optical axis direction, and the zoom lens satisfies the following formula.

[0006] 0.80<f(n+2) / |f(n+3)|(1-1) oal(n+3) / |f(n+3)|<0.58(1-2) in, f(n+2): The focal length of the (n+2)th lens group f(n+3): The focal length of the (n+3)th lens group oal(n+3): The total thickness of the (n+3)th lens group In addition, in order to solve the above-mentioned problems, one aspect of the present invention relates to a camera device that includes the above-described zoom lens and an imaging element that converts the optical image formed by the zoom lens into an electrical signal on the image plane side of the zoom lens.

[0007] Invention Effects According to one aspect of the present invention, a zoom lens and camera device capable of achieving both miniaturization and high performance can be realized. Attached Figure Description

[0008] Figure 1 This diagram schematically illustrates the lens structure at the wide-angle end, intermediate focal length, and infinity focus at the telephoto end of the zoom lens in Embodiment 1.

[0009] Figure 2 This is a diagram showing the longitudinal aberration when focusing at infinity at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens in Embodiment 1.

[0010] Figure 3 This diagram schematically illustrates the lens structure at the wide-angle end, intermediate focal length, and infinity focus at the telephoto end of the zoom lens in Embodiment 2.

[0011] Figure 4 This is a diagram showing the longitudinal aberration when focusing at infinity at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens in Embodiment 2.

[0012] Figure 5 This diagram schematically illustrates the lens structure at the wide-angle end, intermediate focal length, and infinity focus at the telephoto end of the zoom lens in Embodiment 3.

[0013] Figure 6 This is a diagram showing the longitudinal aberration when focusing at infinity at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens in Example 3.

[0014] Figure 7 This diagram schematically illustrates the lens structure at the wide-angle end, intermediate focal length, and infinity focus at the telephoto end of the zoom lens in Embodiment 4.

[0015] Figure 8 This is a diagram showing the longitudinal aberration when focusing at infinity at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens in Example 4.

[0016] Figure 9 This diagram schematically illustrates the lens structure at the wide-angle end, intermediate focal length, and infinity focus at the telephoto end of the zoom lens in Embodiment 5.

[0017] Figure 10 This is a diagram showing the longitudinal aberration when focusing at infinity at the wide-angle end, intermediate focal length, and telephoto end of the zoom lens in Example 5.

[0018] Figure 11 This is a schematic diagram illustrating the structure of a camera device according to one embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures 1. Camera device 2. Main Body 3. Lens tube G1~G7 lens groups Lenses L1 to L17 OA optical axis S-Aperture Stop Detailed Implementation Hereinafter, an embodiment of the present invention will be described in detail. In the following description, the direction along the optical axis of the zoom lens will also be referred to as the "optical axis direction". In addition, the distance along the optical axis from the object-side lens surface of the lens closest to the object side in the zoom lens to the image plane will also be referred to as the "optical length".

[0020] In addition, a "lens group" means a single lens that moves independently, or a collection of two or more lenses that move while maintaining a relative positional relationship. Furthermore, the distance along the optical axis from the object-side lens of the lens closest to the object in the lens group to the image-side lens of the lens closest to the image in the lens group is also called the "total thickness of the lens group".

[0021] A "lens" can be a single lens or a combined lens. Examples of single lenses include biconvex lenses, plano-convex lenses, convex-concave-convex lenses, and concave-concave-convex lenses. A combined lens has a construction in which two or more single lenses are integrally formed without air gaps. Furthermore, a lens can be either a spherical lens or an aspherical lens. An aspherical lens means that at least one of its lens surfaces is aspherical. Examples of aspherical lenses include: composite lenses with a resin layer having an aspherical shape on at least one lens surface, and glass-molded aspherical lenses made of glass material where at least one lens surface is aspherical. Additionally, a lens with positive optical power is also called a "positive lens," and a lens with negative optical power is also called a "negative lens."

[0022] [Zoom lens] [Optical Structure] One embodiment of the present invention relates to a zoom lens comprising, from the object side, a first lens group, a second lens group, an nth lens group including one or more lens groups, a (n+1)th lens group, a (n+2)th lens group, and a (n+3)th lens group. When this zoom lens is composed only of the aforementioned lens groups and does not have any additional lens groups, it is preferable from the viewpoint of balancing miniaturization and high performance.

[0023] <First Lens Group> The first lens group has positive optical power. The types and arrangement of the lenses in the first lens group can be appropriately set within a range that allows the first lens group to exhibit the desired positive optical power as a whole.

[0024] For example, the lens closest to the object side (the first lens) in a zoom lens tends to have a large aperture. Therefore, when the first lens is made of a high-refractive-index glass material as described later in formula (6), it is preferable from the viewpoint of miniaturization by shortening the overall length. By making the first lens from a high-refractive-index glass material, the shape factor of the first lens can be suppressed. In addition, by making the first lens from a high-refractive-index glass material, the circular shape extending towards the object side in the first lens is reduced. Therefore, the risk of the first lens colliding with the ground when the zoom lens or the camera device having the zoom lens is dropped can be reduced, which also brings operational advantages.

[0025] Furthermore, for example, a combined lens can be used for the first lens of the first lens group. When the first lens is a combined lens, it is preferable from the viewpoint of achieving high performance by effectively correcting aberrations.

[0026] <Second Lens Group> The second lens group has negative optical power. The types and arrangement of lenses in the second lens group can be appropriately set within a range that allows the second lens group to exhibit the desired negative optical power overall. For example, for the lens positioned closest to the object side in the second lens group, a negative lens with its concave surface facing the image plane can be used. Using this lens in the second lens group is preferable from the viewpoint of achieving high performance by effectively correcting aberrations.

[0027] <Group n> The nth group includes one or more lens groups. The number of lens groups included in the nth group can be suitably set within the range that achieves the effects of the present invention. Generally, a smaller number of lens groups included in the nth group is advantageous from the viewpoint of miniaturization, while a larger number is advantageous from the viewpoint of high performance. From the viewpoint of balancing miniaturization and high performance, the number of lens groups included in the nth group is preferably 1 to 3.

[0028] Furthermore, in this specification, "n" signifies the sequence number of the lens group closest to the image plane in the nth group within the overall zoom lens. For example, if the nth group has one lens group, that lens group is the third lens group, so n becomes 3. If the nth group has two lens groups, the nth group includes the third and fourth lens groups, so n becomes 4. If the nth group has three lens groups, the nth group includes the third, fourth, and fifth lens groups, so n becomes 5. Thus, in this invention, "n" becomes a value specific to the number of lens groups included in the nth group.

[0029] The overall optical power of the nth group can be suitably set within the range that achieves the effects of the present invention. When the nth group has a positive optical power overall, it is preferable from the viewpoint of achieving high performance by correcting aberrations and miniaturization by shortening the overall length. The nth group, which has a positive optical power overall, may also include lens groups with negative optical power, but when the number of lens groups in the nth group is 2 or less, it is preferable that the lens groups in the nth group have positive optical power for the above-mentioned purposes.

[0030] Furthermore, the nth group preferably includes a joint lens formed by joining three individual lenses. Typically, in zoom lenses, the intermediate lens group with the larger beam diameter (the lens group closer to the object side; in this invention, for example, the nth group) tends to have more lenses with high eccentricity sensitivity. When the nth group includes a joint lens as described above, it is preferable from the viewpoint of consistently ensuring the designed optical performance during the manufacture of the zoom lens. The position and number of the joint lens in the nth group can be suitably set within the range that yields the effects based on the joint lens and the effects of this invention. That is, if the nth group has one lens group, the joint lens can be located in the third lens group; if the nth group has two lens groups, it can be located in at least one of the third and fourth lens groups; and if the nth group has three lens groups, it can be located in at least one of the third to fifth lens groups.

[0031] <n+1th lens group> The (n+1)th lens group has negative optical power. The types and arrangement of lenses in the (n+1)th lens group can be suitably set within the range where the (n+1)th lens group as a whole exhibits the desired negative optical power. When the (n+1)th lens group includes a joint lens, it is preferred from the viewpoint of miniaturization by reducing the overall thickness of the lens group, as well as from the viewpoint of exhibiting the expected optical performance and manufacturing stability.

[0032] <n+2nd lens group> The (n+2)th lens group has positive optical power. The types and arrangement of lenses in the (n+2)th lens group can be suitably set within the range where the (n+2)th lens group as a whole exhibits the desired positive optical power. When the (n+2)th lens group includes a joint lens, it is preferred from the viewpoint of achieving miniaturization by reducing the overall thickness of the lens group, as well as from the viewpoint of exhibiting the expected optical performance and manufacturing stability.

[0033] <The (n+3)th lens group> The (n+3)th lens group has negative optical power. The types and configurations of the lenses in the (n+3)th lens group can be appropriately set within the range where the (n+3)th lens group as a whole exhibits the desired negative optical power.

[0034] In the (n+3)th lens group, the lens closest to the image plane is preferably an aspherical lens. Lenses closest to the image plane tend to have a small beam diameter and allow light to pass through even to the periphery of the lens. Therefore, when this lens is an aspherical lens, it is preferable from the viewpoint of effectively correcting field curvature.

[0035] Furthermore, when the (n+3)th lens group consists of only one aspherical lens, it is advantageous from the perspective of reducing the total thickness of the (n+3)th lens group as the final group. Therefore, having an aspherical lens as the lens closest to the image plane is also a preferred approach from the perspective of miniaturization through shortening the overall length.

[0036] Furthermore, the lens closest to the image plane preferably has a convex lens surface relative to the image plane. In this case, reflected light from the convex surface diffuses from the optical axis side of the lens to the outer periphery, making it difficult to form an image on the image plane. Therefore, it is preferable from the viewpoint of achieving high performance by suppressing the occurrence of harmful ghosting in the lens closest to the image plane, for example, when the lens is a concave-convex lens convex towards the image plane.

[0037] <Aperture Stop> Zoom lenses may include aperture stops. The position of the aperture stop can be suitably set within the range that achieves the effects of the present invention. The aperture stop in a zoom lens is preferably positioned close to the object side (e.g., the nth group). By positioning the aperture stop close to the object side, the angle of light rays from the final group (the (n+3)th lens group) to the image plane (image sensor) can be suppressed. The more the light ray angle is suppressed, the more the oblique incidence characteristics of the peripheral image height are reduced, ensuring a better peripheral light ratio. Furthermore, the shorter the overall optical length, the shorter the distance from the aperture stop to the image sensor (the closer the aperture stop is to the image plane). Therefore, positioning the aperture stop close to the object side is effective from the viewpoint of balancing high performance and shortening the overall length.

[0038] <Other structural elements> In the case where the zoom lens includes one or more lenses having a refractive index expressed by equation (7) described later and an Abbe number expressed by equation (8) described later, it is preferable from the viewpoint of achieving high performance by optimizing the shape factor of the lens. From the above viewpoint, the lens may also be configured in one of the lens groups from the first lens group to the (n+3)th lens group, or multiple such lenses may be included in the zoom lens.

[0039] The number of lens groups in a zoom lens can be suitably determined within the range that achieves the effects of the present invention. Generally, a smaller number of lens groups in a zoom lens is advantageous from the viewpoint of miniaturization, while a larger number is advantageous from the viewpoint of high performance. From the viewpoint of balancing miniaturization and high performance, the number of lens groups in a zoom lens is preferably 6 to 8.

[0040] In addition to the lens group described above, zoom lenses may also include other optical elements within the scope of achieving the effects of the present invention. Examples of other optical elements include filters such as IR cutoff filters that block wavelengths of light such as near-infrared light. For example, when a zoom lens includes such a filter between the final lens and the image plane, it is preferable from the viewpoint of reducing the risk of ghosting caused by interplane reflections by blocking unwanted wavelengths of light during imaging.

[0041] Additionally, the zoom lens may also include an image-stabilizing lens group. An image-stabilizing lens group is a lens group that can move in a direction intersecting the optical axis. Including an image-stabilizing lens group is preferable from the viewpoint of preventing image degradation due to camera shake during recording and achieving high-resolution imaging.

[0042] [action] <Multiply> In a zoom lens, zooming from wide-angle to telephoto can be achieved by varying the air gap along the optical axis between adjacent lens groups. In the zoom lens of this embodiment, the first lens group is fixed in the optical axis direction during zooming. The first lens group generally tends to have the largest lens diameter. When the first lens group is fixed in the optical axis direction during zooming, the first lens group is fixed relative to the image plane, and the center of gravity is stable during photography, which is preferable from the viewpoint of improving the operability of the zoom lens and the imaging device. In addition, when the first lens group is fixed in the optical axis direction during zooming, the mechanical cam structure in the zoom lens is also simplified, and additional components such as sliding frames are not required, which is also effective from the viewpoint of reducing the diameter.

[0043] Furthermore, during zooming, the (n+3)th lens group can also be fixed in the optical axis direction. This structure, where the first lens group and the (n+3)th lens group (which is the final lens group) are fixed in the optical axis direction during zooming, is preferable from the viewpoint of preventing dirt and other contaminants from adhering to the inside of the lens barrel and improving user comfort. Additionally, this structure keeps the overall length of the zoom lens fixed, thus it is also preferable from the viewpoints of miniaturization and operational stability.

[0044] The trajectory of the lens group during zooming can be either straight or curved. Furthermore, this trajectory can be either towards the object side or the image plane side, or it can be a trajectory that moves from one side towards the object side or the image plane side to the other. For example, a straight trajectory during zooming is preferable from the viewpoint of increasing the speed of lens group movement, while a curved trajectory is preferable from the viewpoint of making the overall optical length compact. Additionally, a trajectory towards either the object side or the image plane side during zooming is preferable from the viewpoint of increasing the speed of lens group movement, and a trajectory that moves from one side towards either the object side or the image plane side to the other is preferable from the viewpoint of making the overall optical length compact.

[0045] <Focus> In zoom lenses, focusing is achieved by moving a lens group along the optical axis. Generally, the incident light beam is more convergent for lens groups closer to the image plane. Therefore, lens groups closer to the image plane can be composed of lenses with smaller diameters. Thus, when the lens group that moves during focusing (hereinafter also referred to as the "focusing group") is an image-plane-side lens group, it is preferable from the viewpoints of suppressing changes in the field of view associated with the movement of the focusing group and enabling the focusing group to move quickly and with low drive load during focusing. From this perspective, in this embodiment, it is preferable to designate the (n+1)th lens group as the focusing group.

[0046] Furthermore, having only one lens group simplifies the focusing mechanism, which is preferable from the perspective of miniaturizing and lightening the zoom lens. In this embodiment, the lens group located closer to the image plane than the nth lens group can be suitably constructed from a single joined lens; therefore, from the above perspective, it is also preferable to designate the (n+1)th lens group as the focusing group.

[0047] [Optical Properties] When the zoom lens of this embodiment satisfies at least one or more of the formulas described below, it is preferred from the viewpoint of achieving both miniaturization and high performance of the zoom lens.

[0048] <Equation (1-1)> 0.80<f(n+2) / |f(n+3)|(1-1) in, f(n+2): Focal length of the (n+2)th lens group f(n+3): Focal length of the (n+3)th lens group Equation (1-1) specifies the ratio of the optical power of the (n+2)th lens group to the (n+3)th lens group. When a zoom lens satisfies Equation (1-1), it is preferable from the viewpoint of effectively correcting field curvature. Furthermore, f(n+2) / |f(n+3)| can be suitably determined within a range that allows for effective field curvature correction, for example, it can be 1.45 or less.

[0049] <Equation (1-2)> in, oal(n+3) / |f(n+3)|<0.58(1-2) f(n+3): Focal length of the (n+3)th lens group oal(n+3): Total thickness of the (n+3)th lens group Equation (1-2) defines the relationship between the optical power and the total thickness in the (n+3)th lens group. When a zoom lens satisfies Equation (1-2), it is preferred from the perspective of balancing high performance and reduced overall length. Furthermore, oal(n+3) / |f(n+3)| can be appropriately determined within a range that achieves both high performance and reduced overall length, for example, it can be 0.01 or higher.

[0050] <Formula (2)> 1.0 < b2t / b2w < 6.0 (2) in, b2t: Horizontal magnification of the second lens group when focusing at infinity at the telephoto end. b2w: Horizontal magnification of the second lens group when focusing at infinity at the wide-angle end. Equation (2) specifies the horizontal magnification ratio of the second lens group. When a zoom lens satisfies Equation (2), it is preferred from the viewpoint of balancing a good zoom ratio and miniaturization. If b2t / b2w is 1.0 or less, the difference in horizontal magnification between the wide-angle and telephoto ends of the second lens group is too small, and an appropriate zoom ratio cannot be maintained regardless of the amount of movement during zooming, thus sometimes making it difficult to ensure a good zoom ratio. Furthermore, if b2t / b2w is 6.0 or more, the difference in horizontal magnification between the wide-angle and telephoto ends of the second lens group is too large, requiring a large amount of movement during zooming to maintain an appropriate zoom ratio, thus sometimes making miniaturization difficult.

[0051] From the perspective of achieving a good zoom ratio, b2t / b2w is more preferably larger than 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, or 2.7, with its preference increasing in that order. Furthermore, from the perspective of achieving miniaturization, b2t / b2w is more preferably smaller than 5.8, 5.6, 5.4, 5.2, 5.0, 4.8, 4.6, 4.4, 4.2, 4.0, 3.8, 3.6, 3.4, 3.2, or 3.1, with its preference increasing in that order.

[0052] <Formula (3)> 0.10<oal2 / |f2|<1.20 (3) oal2: Total thickness of the second lens group f2: Focal length of the second lens group Equation (3) specifies the relationship between the optical power and the total thickness of the second lens group. When a zoom lens satisfies Equation (3), it is preferred from the perspective of balancing high performance and shortening the overall length. If oal2 / |f2| is less than 0.1, the optical power of the second lens group weakens, sometimes making it difficult to achieve high performance at both the wide-angle and telephoto ends. Furthermore, if oal2 / |f2| is greater than 1.2, the second lens group becomes excessively thick, thus sometimes making miniaturization difficult.

[0053] From the perspective of balancing high performance at both wide-angle and telephoto ends, oal2 / |f2| is more preferably larger than 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, or 0.62, with the preference increasing in that order. Furthermore, from the perspective of achieving miniaturization, oal2 / |f2| is more preferably smaller than 1.00, 0.95, 0.90, 0.85, 0.80, 0.75, 0.70, or 0.68, with the preference increasing in that order.

[0054] <Formula (4)> 0.30 < oals / oalw (4) in, oals: The distance from the aperture stop to the image plane when focusing at infinity at the wide-angle end. oalw: Total optical length when focusing at infinity at the wide-angle end Equation (4) specifies the position of the aperture stop in a zoom lens. When a zoom lens satisfies Equation (4), it is preferred from the viewpoint of balancing high performance and reduced overall length. From the viewpoint of achieving such an effect, oals / oalw is more preferably larger than 0.32, 0.34, 0.36, 0.38, 0.40, or 0.42, with the preference increasing based on this order. Furthermore, oals / oalw can be appropriately determined within a range that achieves both high performance and reduced overall length, for example, it can be 0.65 or less.

[0055] <Formula (5)> 2.0 < ft / fw < 6.0 (5) in, ft: The focal length of the zoom lens when focusing at infinity at the telephoto end. fw: Focal length of the zoom lens when focusing at infinity at the wide-angle end. Equation (5) specifies the ratio of the focal length at the telephoto end to the focal length at the wide-angle end in a zoom lens. A zoom lens satisfying Equation (5) is preferred from the viewpoint of achieving both miniaturization and high performance, and is particularly preferred from the viewpoint of further improving the effects based on Equations (1-1) and (1-2). From this viewpoint, ft / fw is more preferably larger than 2.1, 2.2, 2.3, 2.4, or 2.5, with the preference increasing according to this order; and more preferably smaller than 5.5, 5.0, 4.5, 4.0, 3.5, or 3, with the preference increasing according to this order.

[0056] <Formula (6)> 1.80 < nd1 (6) in, nd1: The refractive index of the lens closest to the object side, corresponding to the d-line. Equation (6) specifies the glass material of the lens closest to the object (the first lens). When the zoom lens satisfies Equation (6), it is preferred from the perspective of shortening the overall length and suppressing the breakage of the first lens due to falling or collision. From this perspective, nd1 is preferably larger than 1.82, 1.84, 1.86, 1.88 or 1.90, and its preference increases according to this order. In addition, nd1 can be suitably determined within the range that can obtain the above-mentioned effects. For example, the higher the refractive index of the glass material, the more yellow the glass material, so from the perspective of making it easier to control the CCI (color characteristic index), it can be 1.96 or less.

[0057] <Formula (7)> 1.70 < nd < 1.85 (7) in, nd: The refractive index of the lens corresponding to the d-line. Equation (7) specifies the refractive index of a particular lens included in the optics. A zoom lens that satisfies Equation (7) is preferred from the viewpoint of achieving high performance. If nd is 1.7 or less or 1.85 or more, the shape factor of the lens is sometimes difficult to optimize. From the above viewpoint, nd is more preferably larger than 1.70, 1.71, 1.72, 1.73, 1.74, 1.75, or 1.76, with preference increasing based on this order; and more preferably smaller than 1.84, 1.83, 1.82, or 1.81, with preference increasing based on this order.

[0058] <Formula (8)> 29 < vd < 40 (8) in, vd: The Abbe number of the lens corresponding to the d-line. Equation (8) specifies the Abbe number of a particular lens included in the optics. A zoom lens that satisfies Equation (8) is preferred from the viewpoint of achieving high performance. If vd is 29 or less or 40 or more, it can sometimes be difficult to correct magnification chromatic aberration. From the above viewpoint, vd is more preferably greater than 30 or 31, with preference increasing based on this order; and more preferably less than 39, 38, 37, or 36, with preference increasing based on this order.

[0059] Furthermore, in the case of joined lenses, at least one of the two or more joined lenses must satisfy equations (7) and (8).

[0060] [Camera device] One embodiment of the present invention relates to a camera device having the zoom lens described in this embodiment. Figure 11 The structure of the camera device in this embodiment is schematically shown. For example... Figure 11 As shown, the camera device 1 has a main body 2 and a lens barrel 3. The camera device 1 is, for example, a mirrorless single-lens camera.

[0061] The main body 2 has an imaging element I and a protective glass CG. The imaging element I is a component that converts an optical image into an electrical signal, such as a solid-state imaging element. Examples of solid-state imaging elements include CCD (Charge Coupled Device) sensors and CMOS (Complementary Metal Oxide Semiconductor) sensors.

[0062] The lens barrel 3 is detachably mounted to the main body 2. Inside it, along the optical axis OA, there are sequentially arranged a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7. Furthermore, the optical axis OA is a common optical axis for the lens groups of the lens barrel 3 and the imaging element I of the main body 2.

[0063] The first lens group G1 has a positive optical power as a whole. The first lens group G1 is fixed in the optical axis direction during zooming. The first lens group G1 is, for example, composed of a combined lens consisting of a negative lens L1 and a positive lens L2, and a positive lens L3, in sequence from the object side.

[0064] The second lens group G2 has a negative optical power overall. The second lens group G2 is configured to be movable in the optical axis direction. For example, the second lens group G2 is composed of, from the object side, a conjoined lens consisting of a negative lens L4, a biconcave lens L5 and a biconvex lens L6, and a negative lens L7.

[0065] The third lens group G3 has positive optical power overall. The third lens group G3 is configured to be movable in the optical axis direction. The third lens group G3 is, for example, composed of a positive lens L8.

[0066] The fourth lens group G4 has positive optical power overall. The fourth lens group G4 is configured to be movable along the optical axis. For example, starting from the object side, the fourth lens group G4 is composed of a combined lens consisting of a negative lens L9, a biconvex lens L10, and a biconcave lens L11, and a biconvex lens L12. Furthermore, the third lens group G3 and the fourth lens group G4 have positive optical power overall.

[0067] The fifth lens group G5 has a negative optical power overall. The fifth lens group G5 is configured to be movable along the optical axis. For example, the fifth lens group G5 is constructed from a combined lens consisting of a positive lens L13 and a biconcave lens L14. Furthermore, the fifth lens group G5 is configured such that, when focusing (adjusting focus) from an object at infinity to a closer object, focusing is achieved by moving it towards the image plane.

[0068] The sixth lens group G6 has a positive optical power overall. The sixth lens group G6 is configured to be movable in the direction of the optical axis. The sixth lens group G6 is, for example, a combined lens consisting of a positive lens L15 and a negative lens L16.

[0069] The seventh lens group G7 has a negative optical power overall. The seventh lens group G7 is fixed along the optical axis during zooming. The seventh lens group G7 is, for example, composed of a negative lens L17.

[0070] If the third lens group G3 and the fourth lens group G4 are combined into the nth group, the fifth lens group G5 is the (n+1)th lens group, the sixth lens group G6 is the (n+2)th lens group, and the seventh lens group G7 is the (n+3)th lens group, then the above-mentioned zoom lens satisfies at least one of the above-mentioned equations (1-1) to (8). That is, the first lens group G1 to the seventh lens group G7 correspond to a zoom lens of a specific embodiment of the present invention described above.

[0071] In this way, the imaging device 1 includes the zoom lens of this embodiment described above, and an imaging element I that converts the optical image formed by the zoom lens into an electrical signal on the image plane side of the zoom lens. As a result, the imaging device 1 has good optical performance even when it is small and has high magnification.

[0072] The imaging device 1 can be any type of imaging device, including mirrorless single-lens cameras, security cameras, digital cameras, and medical cameras. The zoom lens in this embodiment can be miniaturized even at high magnification. Therefore, the imaging device 1 can be used for various photographic applications.

[0073] Furthermore, the imaging device according to the embodiments of the present invention may also have other structures capable of fixing the image focused by the zoom lens instead of the imaging element I. Examples of such other structures include silver halide thin films.

[0074] Furthermore, within the scope of achieving the effects of the present invention, the imaging device according to the embodiments of the present invention may also include other optical elements in the above-described optical structure, depending on the application of the imaging device. For example, as such other optical elements, the imaging device may also include a parallel planar plate without substantial optical power instead of the protective glass CG. Examples of such other optical elements include an infrared cutoff filter (IRCF).

[0075] 〔Summarize〕 In today's world, where even elementary school students own smartphones, people can easily obtain relatively clear images. While the demand for compact digital cameras has decreased, there remains a certain demand for interchangeable lenses for photography, likely due to their ability to produce images with resolutions exceeding those of smartphones. However, in recent years, products from all manufacturers have achieved high resolutions and offer a wide range of models. Therefore, high performance is arguably a prerequisite for a product to sell.

[0076] On the other hand, unless users are endlessly pursuing superior resolution, they tend to choose products that offer satisfactory resolution within their desired field of view, based on factors such as brand preference, cost, and convenience. Therefore, in a market where high performance is somewhat satisfied, differentiating oneself based on these reasons is important in product development.

[0077] Examples of practical reasons for users to choose products, particularly regarding cost and convenience, include miniaturization, such as shortening the overall optical length and / or reducing the diameter of the zoom lens, and fixing the overall optical length. Miniaturization can reduce product prices by lowering component costs, and also improves the ease of storage and portability of the zoom lens and the camera device equipped with it. Fixing the overall optical length stabilizes the center of gravity during photography, improving operability. Furthermore, with a fixed optical length, there is no need for cams for the fixed lens group. Therefore, as mentioned above, it also helps to reduce the diameter. In this respect, the zoom lens in Patent Document 3 described above has a larger change in the center of gravity balance due to zoom changes because the first lens group moves. Therefore, operability deteriorates, and it is sometimes insufficient from the point of view of convenience.

[0078] The zoom lens of the first embodiment of the present invention comprises, from the object side, a first lens group (G1) having positive optical power, a second lens group (G2) having negative optical power, an nth lens group (G3, G4) including one or more lens groups, an (n+1)th lens group (G5) having negative optical power, an (n+2)th lens group (G6) having positive optical power, and an (n+3)th lens group (G7) having negative optical power. During zooming, the first lens group is fixed in the optical axis (OA) direction, and the zoom lens satisfies the above-described equations (1-1) and (1-2). According to the first embodiment, a zoom lens capable of achieving both miniaturization and high performance can be realized.

[0079] The second aspect of the present invention satisfies equation (2) above in the first aspect. The second aspect is more effective from the viewpoint of balancing a good zoom ratio and miniaturization in zoom lenses.

[0080] The third aspect of the present invention satisfies equation (3) above in either the first or second aspect. The third aspect is more effective from the viewpoint of balancing high performance in zoom lenses and shortening the overall optical length.

[0081] The fourth aspect of the present invention includes an aperture stop (S) in any of the first to third aspects, and satisfies the above-described equation (4). The fourth aspect is more effective from the viewpoint of balancing high performance in zoom lenses and shortening the overall optical length.

[0082] The fifth aspect of the present invention satisfies equation (5) above in any one of the first to fourth aspects. The fifth aspect is more effective from the viewpoint of balancing the miniaturization and high performance of zoom lenses.

[0083] The sixth aspect of the present invention satisfies equation (6) above in any one of the first to fifth aspects. The sixth aspect is more effective from the viewpoints of shortening the overall optical length and suppressing damage to the first lens due to falling or collision.

[0084] The seventh aspect of the present invention, in any one of the first to sixth aspects, has at least one lens that simultaneously satisfies equations (7) and (8) above. The seventh aspect is more effective from the viewpoint of achieving high performance in zoom lenses.

[0085] In the eighth embodiment of the present invention, in any of the first to seventh embodiments, the lens closest to the image plane is an aspherical lens. The eighth embodiment is more effective from the viewpoint of effectively correcting field curvature.

[0086] In the ninth aspect of the present invention, in any one of the first to eighth aspects, the nth group comprises a joined lens formed by joining three single lenses. The ninth aspect is more effective from the viewpoint of improving the stability of achieving the desired optical performance during manufacturing.

[0087] The imaging device according to the tenth aspect of the present invention includes: a zoom lens of any one of the first to ninth aspects, and an imaging element that converts the optical image formed by the zoom lens into an electrical signal at the image plane side of the zoom lens. According to the tenth aspect, an imaging device that can achieve both miniaturization and high performance can be realized.

[0088] According to the above-described embodiments, a zoom lens and camera device that are compact, have high magnification, and possess good optical performance can be provided. This invention has the effect of, for example, expected to contribute to achieving, the United Nations Sustainable Development Goal (SDGs) Goal 9, "Industry, Innovation and Infrastructure."

[0089] This invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

[0090] [Example] The following describes one embodiment of the present invention.

[0091] In various embodiments, various specification tables (Tables 1, 4, 7, or 10) are used. In these specification tables, "No." indicates the surface number, "R" indicates the radius of curvature, "D" indicates the lens thickness or lens spacing, "Nd" indicates the refractive index of the d-line, and "ABV" indicates the Abbe number based on the d-line. Additionally, "ASPH," which is listed along with the surface number, indicates that it is an aspherical surface.

[0092] Additionally, in each embodiment, a table (Table 2, 5, 8, or 11) represents the data for the variable interval. In this table, the data for the wide-angle end, the center focus position, and the telephoto end are represented sequentially from left to right. Furthermore, in this data, "F" represents the focal length of the entire system (zoom lens), "Fno" represents the F-number of the entire system, and "W" represents the half field of view (°) of the entire system. Furthermore, in each embodiment, "D(n)" (where n is an integer) represents the variable interval on the optical axis of the lens surface, which changes during zooming or focusing. Moreover, the units for "R", "D", and "F" are all mm.

[0093] Additionally, tables representing aspherical data are provided in various embodiments (Tables 3, 6, 9, or 12). In these tables, an aspherical surface is defined by the following formula: In this formula, "r" represents the radius, "h" represents the height from the optical axis, "k" represents the conic constant, and "An" represents the aspherical coefficient of order n. In the table, "E+a" represents "×10"... a "Ea" indicates "×10" -a ".

[0094] [Formula 1] Additionally, in each embodiment, the diagram illustrating the lens structure ( Figure 1 , 3 (5 or 7). In the diagram of this lens structure, the lens structure at the wide-angle end, the lens structure at the intermediate focal length, and the lens structure at the telephoto end are schematically shown from top to bottom. Each lens structure diagram shows the lens structure at infinity focus. The arrows between the lens structures schematically represent the movement trajectories of each lens group from the wide-angle end to the intermediate focal length and from the intermediate focal length to the telephoto end. Additionally, the markings G1 to G7 in the diagram represent the first to seventh lens groups, respectively. Furthermore, the intermediate focal length is calculated using the formula "√(fw × ft)". In the formula, "fw" represents the focal length at infinity focus at the wide-angle end, and "ft" represents the focal length at infinity focus at the telephoto end.

[0095] Additionally, in each embodiment, the longitudinal aberration map is represented as ( Figure 2 , 4(6, 8, or 10). In this longitudinal aberration diagram, from top to bottom, the longitudinal aberration diagrams at the wide-angle end, the intermediate focal point, and the telephoto end are represented respectively. Each longitudinal aberration diagram group includes three aberration diagrams, representing spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion aberration (DIS (%)) from left to right. In the spherical aberration diagram, the vertical axis represents the F-value, the solid line represents the characteristics of the d-line (587.56nm), the long dashed line represents the characteristics of the F-line (486.13nm), and the short dashed line represents the characteristics of the C-line (656.27nm). In the astigmatism diagram, the vertical axis represents the field of view, the solid line represents the characteristics of the sagittal plane (shown as S in the diagram), and the dotted line represents the characteristics of the meridional plane (shown as T in the diagram). In the distortion aberration diagram, the vertical axis represents the field of view.

[0096] [Example 1] The zoom lens in Example 1 is as follows Figure 1 As shown, starting from the object side, it consists of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with positive optical power, a fifth lens group G5 with negative optical power, a sixth lens group G6 with positive optical power, and a seventh lens group G7 with negative optical power. The aperture stop S is located on the object side of the fourth lens group G4 and is arranged adjacent to the fourth lens group G4.

[0097] The first lens group G1, starting from the object side, consists of a combined lens formed by a negative concave-convex lens L1 with its convex surface facing the object side and a positive concave-convex lens L2 with its convex surface facing the object side, and a positive concave-convex lens L3 with its convex surface facing the object side.

[0098] The second lens group G2, starting from the object side, consists of a negative concave-convex lens L4 with its convex surface facing the object side, a combined lens formed by a biconcave lens L5 and a biconvex lens L6, and a negative concave-convex lens L7 with its concave surface facing the object side. The negative concave-convex lens L4 is a composite lens with an aspherical resin layer on its object-side surface.

[0099] The third lens group G3 consists of a positive concave-convex lens L8 with its convex surface facing the object side.

[0100] The fourth lens group G4, starting from the object side, consists of a combined lens formed by three lenses: a negative concave-convex lens L9 (convex surface facing the object side), a biconvex lens L10, and a biconcave lens L11, and a biconvex lens L12. The biconvex lens L12 is a glass-molded aspherical lens with both surfaces being aspherical.

[0101] The fifth lens group G5 is a combined lens consisting of a positive concave-convex lens L13 with its concave surface facing the object side and a biconcave lens L14.

[0102] The sixth lens group G6 is a combined lens consisting of a positive concave-convex lens L15 with its concave surface facing the object side and a negative concave-convex lens L16 with its concave surface facing the object side.

[0103] The seventh lens group G7 consists of a negative concave-convex lens L17 with its concave surface facing the object side. The negative concave-convex lens L17 is a glass-molded aspherical lens with both surfaces being aspherical.

[0104] In the zoom lens of Embodiment 1, the third lens group G3 and the fourth lens group G4 constitute the nth lens group described above. The fifth lens group G5 is equivalent to the (n+1)th lens group described above, the sixth lens group G6 is equivalent to the (n+2)th lens group described above, and the seventh lens group G7 is equivalent to the (n+3)th lens group described above.

[0105] The zoom lens of Example 1 achieves magnification by changing the air gap on the optical axis between adjacent lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, and the second lens group G2 moves towards the image plane. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 all move towards the image plane in a parabolic trajectory as shown in the figure, eventually moving to a position closer to the image plane than at the wide-angle end when zooming towards the telephoto end. The sixth lens group G6 moves towards the image plane, and the seventh lens group G7 is fixed.

[0106] In Example 1, focusing (adjusting) from an object at infinity to a closer object in the zoom lens is achieved by moving the fifth lens group G5 toward the image plane.

[0107] Tables 1 to 3 show the various specifications, variable spacing data, and aspherical data for the zoom lens of Example 1. Additionally, Figure 2 The diagram shows the aberration in the zoom lens of Example 1. The lens including surface number 10 and the lens including surface number 17 are both lenses that satisfy both of the above equations (7) and (8).

[0108] [Table 1]

[0109] [Table 2]

[0110] [Table 3]

[0111] [Example 2] The zoom lens in Example 2 is as follows Figure 3As shown, starting from the object side, it consists of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with positive optical power, a fifth lens group G5 with negative optical power, a sixth lens group G6 with positive optical power, and a seventh lens group G7 with negative optical power. The aperture stop S is located on the object side of the fourth lens group G4 and is arranged adjacent to the fourth lens group G4.

[0112] The first lens group G1, starting from the object side, consists of a conjoined lens formed by a negative concave-convex lens L1 with its convex surface facing the object side and a biconvex lens L2, and a positive concave-convex lens L3 with its convex surface facing the object side.

[0113] The second lens group G2, starting from the object side, consists of a negative concave-convex lens L4 with its convex surface facing the object side, a combined lens formed by a biconcave lens L5 and a biconvex lens L6, and a negative concave-convex lens L7 with its concave surface facing the object side. The negative concave-convex lens L4 is a composite lens with an aspherical resin layer on its object-side surface.

[0114] The third lens group G3 consists of a positive concave-convex lens L8 with its convex surface facing the object side.

[0115] The fourth lens group G4, starting from the object side, consists of a combined lens formed by three lenses: a negative concave-convex lens L9 (convex surface facing the object side), a biconvex lens L10, and a biconcave lens L11, and a biconvex lens L12. The biconvex lens L12 is a glass-molded aspherical lens with both surfaces being aspherical.

[0116] The fifth lens group G5 is composed of a combined lens consisting of a biconvex lens L13 and a biconcave lens L14.

[0117] The sixth lens group G6 is a combined lens consisting of a biconvex lens L15 and a negative concave-convex lens L16 with its concave surface facing the object side.

[0118] The seventh lens group G7 consists of a negative concave-convex lens L17 with its concave surface facing the object side. The negative concave-convex lens L17 is a glass-molded aspherical lens with both surfaces being aspherical.

[0119] In the zoom lens of Embodiment 2, the third lens group G3 and the fourth lens group G4 constitute the nth lens group described above. The fifth lens group G5 is equivalent to the (n+1)th lens group described above, the sixth lens group G6 is equivalent to the (n+2)th lens group described above, and the seventh lens group G7 is equivalent to the (n+3)th lens group described above.

[0120] The zoom lens of Example 2 achieves magnification by changing the air gap on the optical axis between adjacent lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, and the second lens group G2 moves towards the image plane. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 all move towards the image plane in a parabolic trajectory as shown in the figure, eventually moving to a position closer to the object plane than at the wide-angle end when zooming towards the telephoto end. The sixth lens group G6 moves towards the image plane, and the seventh lens group G7 is fixed.

[0121] In Example 2, focusing from an object at infinity to a closer object in the zoom lens is achieved by moving the fifth lens group G5 toward the image plane.

[0122] Tables 4 to 6 show the various specifications, variable interval data, and aspherical data for the zoom lens in Example 2. Additionally, Figure 4 The diagram shows the aberration in the zoom lens of Embodiment 2. The lens including surface number 10 and the lens including surface number 17 are both lenses that satisfy both of the above equations (7) and (8).

[0123] [Table 4]

[0124] [Table 5]

[0125] [Table 6]

[0126] [Example 3] The zoom lens in Example 3 is as follows Figure 5 As shown, starting from the object side, it consists of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with positive optical power, a fifth lens group G5 with negative optical power, a sixth lens group G6 with positive optical power, and a seventh lens group G7 with negative optical power. The aperture stop S is located on the object side of the fourth lens group G4 and is arranged adjacent to the fourth lens group G4.

[0127] The first lens group G1, starting from the object side, consists of a combined lens formed by a negative concave-convex lens L1 with its convex surface facing the object side and a positive concave-convex lens L2 with its convex surface facing the object side, and a positive concave-convex lens L3 with its convex surface facing the object side.

[0128] The second lens group G2, starting from the object side, consists of a negative concave-convex lens L4 with its convex surface facing the object side, a combined lens formed by a biconcave lens L5 and a biconvex lens L6, and a negative concave-convex lens L7 with its concave surface facing the object side. The negative concave-convex lens L4 is a composite lens with an aspherical resin layer on its object-side surface.

[0129] The third lens group G3 consists of a positive concave-convex lens L8 with its convex surface facing the object side.

[0130] The fourth lens group G4, starting from the object side, consists of a combined lens formed by three lenses: a negative concave-convex lens L9 (convex surface facing the object side), a biconvex lens L10, and a biconcave lens L11, and a biconvex lens L12. The biconvex lens L12 is a glass-molded aspherical lens with both surfaces being aspherical.

[0131] The fifth lens group G5 is a combined lens consisting of a positive concave-convex lens L13 with its concave surface facing the object side and a biconcave lens L14.

[0132] The sixth lens group G6 is a combined lens consisting of a biconvex lens L15 and a negative concave-convex lens L16 with its concave surface facing the object side.

[0133] The seventh lens group G7 consists of a negative concave-convex lens L17 with its concave surface facing the object side. The negative concave-convex lens L17 is a glass-molded aspherical lens with both surfaces being aspherical.

[0134] In the zoom lens of Embodiment 3, the third lens group G3 and the fourth lens group G4 constitute the nth group described above. The fifth lens group G5 is equivalent to the (n+1)th lens group described above, the sixth lens group is equivalent to the (n+2)th lens group described above, and the seventh lens group G7 is equivalent to the (n+3)th lens group described above.

[0135] In the zoom lens of Embodiment 3, zoom is achieved by changing the air gap on the optical axis between adjacent lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, and the second lens group G2 moves towards the image plane. The third lens group G3, the fourth lens group G4, and the fifth lens group G5 all move towards the image plane in a parabolic trajectory as shown in the figure, eventually moving to a position closer to the image plane than at the wide-angle end when zooming towards the telephoto end. The sixth lens group G6 moves towards the image plane, and the seventh lens group G7 is fixed.

[0136] In Example 3, focusing from an object at infinity to a closer object in the zoom lens is achieved by moving the fifth lens group G5 toward the image plane.

[0137] Tables 7 to 9 show the various specifications, variable spacing data, and aspherical data for the zoom lens in Example 3. Additionally, Figure 6 The diagram shows the aberration in the zoom lens of Embodiment 3. The lens including surface number 10 and the lens including surface number 17 are both lenses that satisfy both of the above equations (7) and (8).

[0138] [Table 7]

[0139] [Table 8]

[0140] [Table 9]

[0141] [Example 4] The zoom lens in Example 4 is as follows Figure 7 As shown, starting from the object side, it consists of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with negative optical power, a fifth lens group G5 with positive optical power, and a sixth lens group G6 with negative optical power. The aperture stop S is disposed inside the third lens group G3.

[0142] The first lens group G1, starting from the object side, consists of a combined lens formed by a negative concave-convex lens L1 with its convex surface facing the object side and a positive concave-convex lens L2 with its convex surface facing the object side, and a positive concave-convex lens L3 with its convex surface facing the object side.

[0143] The second lens group G2, starting from the object side, consists of a negative concave-convex lens L4 with its convex surface facing the object side, a combined lens formed by a biconcave lens L5 and a biconvex lens L6, and a negative concave-convex lens L7 with its concave surface facing the object side. The negative concave-convex lens L4 is a composite lens with an aspherical resin layer on its object-side surface.

[0144] The third lens group G3, starting from the object side, consists of a concentric lens formed by three lenses: a positive concave-convex lens L8 with its convex surface facing the object side, a negative concave-convex lens L9 with its convex surface facing the object side, a biconvex lens L10, and a biconcave lens L11, and a biconvex lens L12. The biconvex lens L12 is a glass-molded aspherical lens with both sides being aspherical.

[0145] The fourth lens group G4 is a combined lens consisting of a single convex lens L13 with its plane facing the object side and a double concave lens L14.

[0146] The fifth lens group G5 is a combined lens consisting of a biconvex lens L15 and a negative concave-convex lens L16 with its concave surface facing the object side.

[0147] The sixth lens group G6, starting from the object side, consists of a combined lens formed by a positive concave-convex lens L17 with its concave surface facing the object side and a biconcave lens L18, and a negative concave-convex lens L19 with its concave surface facing the object side. The negative concave-convex lens L19 is a glass-molded aspherical lens with both surfaces being aspherical.

[0148] In the zoom lens of Embodiment 4, the third lens group G3 is equivalent to the nth group mentioned above, the fourth lens group G4 is equivalent to the (n+1)th lens group mentioned above, the fifth lens group G5 is equivalent to the (n+2)th lens group mentioned above, and the sixth lens group G6 is equivalent to the (n+3)th lens group mentioned above.

[0149] The zoom lens of Example 4 achieves magnification by changing the air gap on the optical axis between adjacent lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, and the second lens group G2 moves towards the image plane. The third lens group G3 and the fourth lens group G4 both move towards the image plane in a parabolic trajectory as shown in the figure, eventually moving to a position closer to the image plane than at the wide-angle end when zooming towards the telephoto end. The fifth lens group G5 moves towards the image plane, and the sixth lens group G6 is fixed.

[0150] In Example 4, focusing from an object at infinity to a closer object in the zoom lens is achieved by moving the fourth lens group G4 toward the image plane.

[0151] Tables 10 to 12 show the various specifications, variable interval data, and aspherical data for the zoom lens of Example 4. Additionally, Figure 8 The diagram shows the aberration in the zoom lens of Example 4. The lens including surface number 10 and the lens including surface number 17 are both lenses that satisfy both of the above equations (7) and (8).

[0152] [Table 10]

[0153] [Table 11]

[0154] [Table 12]

[0155] [Example 5] The zoom lens in Example 5 is as follows Figure 9 As shown, starting from the object side, the lens group consists of a first lens group G1 with positive optical power, a second lens group G2 with negative optical power, a third lens group G3 with positive optical power, a fourth lens group G4 with negative optical power, a fifth lens group G5 with positive optical power, a sixth lens group G6 with negative optical power, a seventh lens group G7 with positive optical power, and an eighth lens group G8 with negative optical power. The aperture stop is located on the object side of the fourth lens group G4, adjacent to the third lens group G3.

[0156] The first lens group G1, starting from the object side, consists of a combined lens formed by a negative concave-convex lens L1 with its convex surface facing the object side and a positive concave-convex lens L2 with its convex surface facing the object side, and a positive concave-convex lens L3 with its convex surface facing the object side.

[0157] The second lens group G2, starting from the object side, consists of a negative concave-convex lens L4 with its convex surface facing the object side, a combined lens formed by a biconcave lens L5 and a biconvex lens L6, and a negative concave-convex lens L7 with its concave surface facing the object side. The negative concave-convex lens L4 is a composite lens with an aspherical resin layer on its object-side surface.

[0158] The third lens group G3 consists of a positive concave-convex lens L8 with its convex surface facing the object side.

[0159] The fourth lens group G4 is a combined lens consisting of three lenses: a negative concave-convex lens L9 with its convex surface facing the object side, a biconvex lens L10, and a biconcave lens L11.

[0160] The fifth lens group G5 consists of a biconvex lens L12. The biconvex lens L12 is a glass-molded aspherical lens with both sides being aspherical.

[0161] The sixth lens group G6 is a combined lens consisting of a positive concave-convex lens L13 with its concave surface facing the object side and a biconcave lens L14.

[0162] The seventh lens group G7 is a combined lens consisting of a positive concave-convex lens L15 with its concave surface facing the object side and a negative concave-convex lens L16 with its concave surface facing the object side.

[0163] The eighth lens group G8 consists of a negative concave-convex lens L17 with its concave surface facing the object side. The negative concave-convex lens L17 is a glass-molded aspherical lens with both surfaces being aspherical.

[0164] In the zoom lens of Embodiment 5, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute the aforementioned nth group. The sixth lens group G6 corresponds to the aforementioned (n+1)th group, the seventh lens group G7 corresponds to the aforementioned (n+2)th group, and the eighth lens group G8 corresponds to the aforementioned (n+3)th group.

[0165] In the zoom lens of Embodiment 5, zoom is achieved by changing the air gap on the optical axis between adjacent lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, and the second lens group G2 moves towards the image side. The third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 all move towards the image plane in a parabolic trajectory as shown in the figure, eventually moving to a position closer to the image plane than at the wide-angle end when zooming towards the telephoto end. The seventh lens group G7 moves towards the image plane, and the eighth lens group G8 is fixed.

[0166] In Example 5, focusing from an object at infinity to a closer object in the zoom lens is achieved by moving the sixth lens group G6 toward the image plane.

[0167] Tables 13 to 15 show the various specifications, variable interval data, and aspherical data for the zoom lens of Example 5. Additionally, Figure 10 The diagram shows the aberration in the zoom lens of Embodiment 5. The lens including surface number 10 and the lens including surface number 17 are both lenses that satisfy both of the above equations (7) and (8).

[0168] [Table 13]

[0169] [Table 14]

[0170] [Table 15]

[0171] Table 16 shows the calculated values ​​of the above formulas in Examples 1 to 5.

[0172] [Table 16]

Claims

1. A zoom lens, comprising, from the object side, a first lens group having positive optical power, a second lens group having negative optical power, an nth lens group including one or more lens groups, an (n+1)th lens group having negative optical power, an (n+2)th lens group having positive optical power, and an (n+3)th lens group having negative optical power. During zooming, the first lens group is fixed in the optical axis direction, and The zoom lens satisfies the following formula: 0.80<f(n+2) / |f(n+3)|(1-1) oal(n+3) / |f(n+3)|<0.58(1-2) in, f(n+2): The focal length of the (n+2)th lens group f(n+3): The focal length of the (n+3)th lens group oal(n+3): The total thickness of the (n+3)th lens group.

2. The zoom lens as described in claim 1, satisfying the following formula: 1.0 < b2t / b2w < 6.0 (2) in, b2t: Horizontal magnification of the second lens group when focusing at infinity at the telephoto end. b2w: Horizontal magnification of the second lens group when focusing at infinity at the wide-angle end.

3. The zoom lens as described in claim 1, satisfying the following formula: 0.10<oal2 / |f2|<1.20 (3) in, oal2: Total thickness of the second lens group f2: The focal length of the second lens group.

4. The zoom lens as described in claim 1, The zoom lens includes an aperture stop and satisfies the following formula: 0.30 < oals / oalw (4) in, oals: The distance from the aperture stop to the image plane when focusing at infinity at the wide-angle end. oalw: The total optical length when focusing at infinity at the wide-angle end.

5. The zoom lens as described in claim 1, satisfying the following formula: 1.80 < nd1 (6) in, nd1: The refractive index of the lens closest to the object side, corresponding to the d-line.

6. The zoom lens as described in claim 1, comprising at least one lens that simultaneously satisfies the following formula: 1.70 < nd < 1.85 (7) 29 < vd < 40 (8) in, nd: The refractive index of the lens corresponding to the d-line. vd: The Abbe number of the lens corresponding to the d-line.

7. The zoom lens as described in claim 1, The nth group has a joined lens formed by joining three individual lenses.

8. A camera device comprising a zoom lens as described in any one of claims 1 to 7, and an imaging element that converts an optical image formed by the zoom lens into an electrical signal at the image plane side of the zoom lens.

Images