Zoom lens and imaging device

Abstract

To provide a zoom lens with a wide angle of view and good optical performance. [Solution] The zoom lens L0 is composed of a first lens group L1 with negative refractive power, arranged sequentially from the object side to the image side, an intermediate group LN with negative refractive power including at least one lens group, and a rear group LP with positive refractive power including multiple lens groups. When zooming, the first lens group does not move, but the spacing between adjacent lens groups changes. At the wide-angle end, the air gap between the intermediate group and the rear group is maximized. The intermediate group includes multiple negative lenses. The rear group includes a focusing lens group that moves during focusing. When the focal length of the first lens group is fL1, and the distance on the optical axis from the lens surface closest to the object in the intermediate group to the lens surface closest to the image in the intermediate group at the wide-angle end is DLNw, the condition -5.0 ≤ DLNw / fL1 ≤ -0.7 is satisfied.

Description

[Technical Field]

[0001] This invention relates to an imaging device used for imaging and the like. [Background technology]

[0002] Zoom lenses used in imaging devices are required to have a wide angle of view and good optical performance. As a wide-angle zoom lens, a negative-lead type zoom lens is disclosed, such as the one disclosed in Patent Document 1, in which the lens group with negative refractive power is positioned closest to the object. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-104025 [Overview of the project] [Problems that the invention aims to solve]

[0004] There is a demand for zoom lenses that offer a wider field of view and better optical performance than conventional lenses. [Means for solving the problem]

[0005] A zoom lens as one aspect of the present invention is composed of a first lens group with negative refractive power, arranged sequentially from the object side to the image side, an intermediate group with negative refractive power including at least one lens group, and a rear group with positive refractive power including multiple lens groups. During zooming, the first lens group does not move, but the spacing between adjacent lens groups changes. At the wide-angle end, the air gap between the intermediate group and the rear group is maximized. The intermediate group includes multiple negative lenses. The rear group includes a focusing lens group that moves during focusing. When the focal length of the first lens group is fL1, and the distance on the optical axis from the lens surface closest to the object in the intermediate group to the lens surface closest to the image in the intermediate group at the wide-angle end is DLNw, -5.0 ≤ DLNw / fL1 ≤ -0.7 It is characterized by satisfying the following conditions. Furthermore, an imaging device equipped with the above-mentioned zoom lens also constitutes another aspect of the present invention. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a zoom lens with a wide angle of view and good optical performance. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-sectional view of the zoom lens of Example 1. [Figure 2] This is an aberration diagram of the zoom lens of Example 1. [Figure 3] This is a cross-sectional view of the zoom lens of Example 2. [Figure 4] This is an aberration diagram of the zoom lens in Example 2. [Figure 5] This is a cross-sectional view of the zoom lens of Example 3. [Figure 6] This is an aberration diagram of the zoom lens in Example 3. [Figure 7] This is a cross-sectional view of the zoom lens of Example 4. [Figure 8] This is an aberration diagram of the zoom lens in Example 4. [Figure 9] This is a cross-sectional view of the zoom lens of Example 5. [Figure 10] This is an aberration diagram of the zoom lens in Example 5. [Figure 11] This is a cross-sectional view of the zoom lens of Example 6. [Figure 12] This is an aberration diagram of the zoom lens of Example 6. [Figure 13] This is a cross-sectional view of the zoom lens of Example 7. [Figure 14] This is an aberration diagram of the zoom lens in Example 7. [Figure 15] This is a schematic diagram of an imaging device equipped with a zoom lens according to Examples 1 to 7. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0009] FIG. 1, FIG. 3, FIG. 5, FIG. 7, FIG. 9, FIG. 11, and FIG. 13 each show a cross-section of the zoom lens L0 of Examples 1 to 7 in a state of being focused on an object at the wide-angle end and at infinity (hereinafter referred to as the infinity focus state). The zoom lens L0 of each example is used in an imaging device such as a digital video camera, a digital still camera, a broadcast camera, a silver halide film camera, a surveillance camera, or an optical device including an interchangeable lens.

[0010] In each figure, the left side is the object side (front side), and the right side is the image side (rear side). The zoom lens L0 of each example has a plurality of lens groups. In a zoom lens, a lens group is a collection of one or more lenses that move together or do not move during zooming (zooming) between the wide-angle end and the telephoto end. That is, the distance between adjacent lens groups changes during zooming. A lens group may include an aperture stop. Also, the wide-angle end and the telephoto end each indicate a zoom state of the maximum picture angle (shortest focal length) and the minimum picture angle (longest focal length) when the lens group that moves during zooming is located at both ends of the range where it can move mechanically or controllably on the optical axis. Also, regarding the number of lenses constituting each lens group, the number of lenses in one cemented lens in which two lenses are cemented together is two.

[0011] In each figure, Li indicates the i-th lens group (i = 1, 2, 3,...) counted from the object side among the lens groups included in the zoom lens L0. For example, L1 indicates the first lens group. LN is an intermediate group arranged on the image side of the first lens group L1. LP is a rear group arranged on the image side of the intermediate group LN.

[0012] SP is an aperture stop. IP is an image plane. On the image plane IP, an imaging surface (light-receiving surface) of an imaging element such as a CCD sensor or a CMOS sensor or a film surface (photosensitive surface) of a silver halide film is arranged.

[0013] In each figure, the movement trajectory of the lens group as it zooms from the wide-angle end to the telephoto end is shown by a solid arrow below the lens group as it zooms. Similarly, the direction of movement of the focusing lens group LF as it zooms from infinity to close is shown by a dashed arrow below the focusing lens group as it zooms.

[0014] The zoom lens L0 in each embodiment is composed of a first lens group L1 with negative refractive power, arranged sequentially from the object side to the image side; an intermediate group LN having negative refractive power as a whole, including at least one lens group; and a rear group LP having positive refractive power as a whole, including multiple lens groups. The intermediate group LN includes multiple negative lenses. Furthermore, in the zoom lens L0 of each embodiment, the air gap between the intermediate group LN and the rear group LP is maximized at the wide-angle end. This makes it possible to achieve a sufficient magnification ratio.

[0015] The zoom lens L0 of Examples 1 to 4 is composed of a first lens group L1, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power. The second lens group L2 constitutes the intermediate group LN, and the third lens group L3, the fourth lens group L4, and the fifth lens group L5 constitute the rear group LP. The third lens group L3 includes an aperture diaphragm SP.

[0016] When zooming from the wide-angle end to the telephoto end, the first lens group L1 does not move, while the second lens group L2 moves towards the image and then towards the object. The third lens group L3, the fourth lens group L4, and the fifth lens group L5 move monotonically towards the object. Also, when focusing from infinity to close, the fourth lens group L4 moves towards the object.

[0017] The zoom lens L0 of Example 5 is composed of a first lens group L1, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with positive refractive power, and a sixth lens group L6 with negative refractive power. The second and third lens groups L2 and L3 constitute the intermediate group LN, and the fourth, fifth, and sixth lens groups L4 constitute the rear group LP. The fourth lens group L4 includes an aperture diaphragm SP.

[0018] When zooming from the wide-angle end to the telephoto end, the first lens group L1 does not move, while the second and third lens groups L2 and L3 move towards the image and then towards the object. The fourth, fifth, and sixth lens groups L4, L5, and L6 move monotonically towards the object. Also, when focusing from infinity to close, the fifth lens group L5 moves towards the object.

[0019] The zoom lens L0 of Example 6 is composed of a first lens group L1, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with positive refractive power, and a sixth lens group L6 with negative refractive power. The second and third lens groups L2 and L3 constitute the intermediate group LN, and the fourth, fifth, and sixth lens groups L4, L5, and L6 constitute the rear group LP. The fourth lens group L4 includes an aperture diaphragm SP.

[0020] When zooming from the wide-angle end to the telephoto end, the first lens group L1 does not move, while the second and third lens groups L2 and L3 move towards the image and then towards the object. The fourth, fifth, and sixth lens groups L4, L5, and L6 move monotonically towards the object. Also, when focusing from infinity to close, the fifth lens group L5 moves towards the object.

[0021] The zoom lens L0 of Example 7 is composed of a first lens group L1, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, a sixth lens group L6 with negative refractive power, and a seventh lens group L7 with positive refractive power. The second and third lens groups L2 and L3 constitute the intermediate group LN, and the fourth, fifth, sixth, and seventh lens groups L4, L5, L6, and L7 constitute the rear group LP. The fifth lens group L5 includes an aperture diaphragm SP.

[0022] When zooming from the wide-angle end to the telephoto end, the first lens group L1 does not move, while the second and third lens groups L2 and L3 move towards the image side and then towards the object side. The fourth, fifth, and sixth lens groups L4, L5, and L6 move monotonically towards the object side. Also, when focusing from infinity to close, the sixth lens group L6 moves towards the image side.

[0023] The projection method for the zoom lenses in Examples 1-3 is equi-angle (equidistance) projection (Y=fθ), while the projection method for the zoom lenses in Examples 4-7 is equi-solid angle projection (Y=2fsin(θ / 2)). Other projection methods may also be used.

[0024] Furthermore, in the optical system L0 of each embodiment, an optical block such as a parallel plate without refractive power, such as a low-pass filter or an infrared cut filter, may be provided between the lens closest to the image and the image plane IP.

[0025] Next, the characteristics of the zoom lens L0 in each embodiment will be described. The zoom lens L0 in each embodiment is a negative-lead type zoom lens in which the refractive power of the first lens group L1 is negative. Negative-lead type zoom lenses are particularly effective for wide-angle applications.

[0026] However, in negative-lead zoom lenses, the lens configuration tends to be asymmetrical with respect to the aperture SP, making it difficult to correct various aberrations. Also, as the angle of view widens, the height of the off-axis light rays incident on the first lens group L1 increases, which increases the diameter and weight of the first lens group L1. For this reason, in this embodiment, the robustness of the zoom lens is enhanced by making the first lens group L1 immovable (fixed) with respect to the image plane IP during zooming.

[0027] To achieve good optical performance by keeping the first lens group L1 stationary during zooming, it is important to appropriately configure the intermediate group LN and the rear group LP. In this embodiment, the intermediate group LN includes multiple negative lenses. This suppresses chromatic aberration and distortion. Furthermore, by including multiple lens groups in the rear group LP, a sufficient zoom ratio (e.g., about 2x) is achieved while maintaining good optical performance. Since the height of the off-axis rays incident on the rear group LP is relatively low, the diameter of the rear group LP tends to be small. Therefore, by placing the focusing lens group LF within the rear group LP, it becomes easier to miniaturize the focusing lens group LF, and thus easier to speed up focusing.

[0028] Furthermore, in each embodiment, the zoom lens L0 preferably satisfies the following condition (1), where fL1 is the focal length of the first lens group L1, and DLNw is the distance along the optical axis from the lens surface closest to the object in the intermediate group LN to the lens surface closest to the image in the intermediate group LN at the wide-angle end.

[0029] -5.0 ≤ DLNw / fL1 ≤ -0.7 (1) The conditions in equation (1) show an appropriate relationship between the focal length fL1 of the first lens group L1 and the distance DLNw, which represents the thickness of the intermediate group LN at the wide-angle end. In order to capture light rays from a wide angle of view and guide them to the image plane, the intermediate group LN needs to have many lens surfaces. Also, in wide-angle zoom lenses, the height of off-axis light rays incident on the intermediate group LN increases, so off-axis aberrations such as chromatic aberration and distortion that occur within the intermediate group LN increase, and in order to suppress these, the intermediate group LN needs to have an appropriate thickness. If the thickness becomes long enough so that DLNw / fL1 falls below the lower limit of equation (1), it becomes difficult to miniaturize the zoom lens, which is undesirable. If the thickness of the intermediate group LN becomes short enough so that DLNw / fL1 exceeds the upper limit of equation (1), it becomes difficult to correct off-axis aberrations such as chromatic aberration and distortion, which is undesirable.

[0030] Furthermore, it is more preferable to set the lower limit of equation (1) to -2.4, -2.2, -2.0, -1.8, or -1.6. Also, it is more preferable to set the upper limit of equation (1) to -0.75, -0.8, -0.85, or -0.9.

[0031] By satisfying the above configuration and conditions, a compact zoom lens with good optical performance can be obtained.

[0032] The zoom lens L0 of each embodiment preferably satisfies at least one of the following conditions of equations (3) to (14).

[0033] 0.7 ≤ MLP / fL1 ≤ 5.0 (2) -3.3 ≤ fL1 / fw ≤ -1.7 (3) 2.0 ≤ fLNw / fL1 ≤ 3.5 (4) 1.4 ≤ fG1 / fL1 ≤ 3.0 (5) 0.20 ≤ fG1 / fG2 ≤ 1.60 (6) 3.5 ≤ fLF / fw ≤ 15.0 (7) -4.1 ≤ fLF / fL1 ≤ -1.8 (8) -1.3 ≤ fL1 / fLPw ≤ -0.4 (9) 1.3 ≤ Skw / fw ≤ 6.0 (10) 0.39 ≤ DSPw / Skw ≤ 2.90 (11) 1.65 ≤ ndG1 ≤ 2.20 (12) 1.3≦(R1+R2) / (R1-R2)≦3.0 (13) 1.5 ≤ Yta / Ywa ≤ 3.0 (14) The condition in equation (2) shows an appropriate relationship between the maximum amount of movement MLP among the multiple lens groups included in the rear group LP when zooming from the wide-angle end to the telephoto end, and the focal length fL1 of the first lens group L1. The amount of movement of the lens group is the difference between the position of the lens group at the wide-angle end and the position of the lens group at the telephoto end, and does not include the amount of movement back and forth. It is considered positive when the lens group is positioned closer to the image at the telephoto end compared to the wide-angle end.

[0034] If the travel amount MLP becomes shorter so that MLP / fL1 falls below the lower limit of equation (2), it becomes difficult to secure a sufficient magnification ratio, which is undesirable. If the travel amount MLP becomes longer so that MLP / fL1 exceeds the upper limit of equation (2), it becomes difficult to miniaturize the zoom lens, which is also undesirable.

[0035] Furthermore, it is more preferable to set the lower limit of equation (2) to 0.8, 0.9, 1.0, or 1.1. It is also more preferable to set the upper limit of equation (2) to 4.0, 3.0, 2.0, 1.8, 1.6, or 1.4. The conditions in equation (3) indicate an appropriate relationship between the focal length fL1 of the first lens group L1 and the total focal length fw of the zoom lens L0 system at the wide-angle end. By appropriately setting the focal length fL1 of the first lens group L1, distortion can be suppressed while correcting chromatic aberration and field curvature can be easily achieved. If the focal length fL1 of the first lens group L1 is increased so that fL1 / fw falls below the lower limit of equation (3), it is advantageous for aberration correction, but it becomes difficult to achieve both wide-angle and miniaturization. It also tends to lead to an increase in the diameter of the first lens group L1, making it difficult to miniaturize the optical system, which is undesirable. If the focal length fL1 of the first lens group L1 is shortened so that fL1 / fw exceeds the upper limit of equation (3), the change in image height due to off-axis coma aberration becomes large, making it difficult to correct field curvature and astigmatism, which is undesirable.

[0036] Furthermore, it is more preferable to set the lower limit of equation (3) to -3.4, -3.3, -3.2, -3.1, or -3.0. Also, it is more preferable to set the upper limit of equation (3) to -1.8, -1.9, or -2.0.

[0037] The condition in equation (4) indicates an appropriate relationship between the focal length fLNw of the intermediate lens group LN and the focal length fL1 of the first lens group L1 at the wide-angle end. If the focal length fL1 of the first lens group L1 is increased so that fLNw / fL1 falls below the lower limit of equation (4), it is advantageous for aberration correction, but it becomes difficult to achieve both wide-angle and miniaturization. It also tends to lead to an increase in the diameter of the first lens group L1, making it difficult to miniaturize the optical system, which is undesirable. If the focal length fL1 of the first lens group L1 is shortened so that fLNw / fL1 exceeds the upper limit of equation (4), the image height change due to off-axis coma aberration becomes large, making it difficult to correct field curvature and astigmatism, which is undesirable. Furthermore, it is more preferable to set the lower limit of equation (4) to 2.1 or 2.2. Also, it is more preferable to set the upper limit of equation (4) to 3.1 or 3.0.

[0038] The condition in equation (5) indicates an appropriate relationship between the focal length fG1 of the first lens G1 closest to the object in the first lens group L1 and the focal length fL1 of the first lens group L1. The first lens G1 is a negative lens. If the focal length fG1 of the first lens G1 is shortened so that fG1 / fL1 falls below the lower limit of equation (5), it is undesirable because it becomes difficult to correct field curvature and distortion. If the focal length fG1 of the first lens G1 is lengthened so that fG1 / fL1 exceeds the upper limit of equation (5), it is advantageous for aberration correction, but it becomes difficult to achieve both wide-angle and miniaturization. It also tends to lead to an increase in the diameter of the first lens group L1, making it difficult to miniaturize the optical system, which is undesirable.

[0039] Furthermore, it is more preferable to set the lower limit of equation (5) to 1.5, 1.6, or 1.7. Also, it is more preferable to set the upper limit of equation (5) to 2.9, 2.8, 2.7, or 2.6.

[0040] The conditions in equation (6) indicate an appropriate relationship between the focal length fG1 of the first lens G1 in the first lens group L1 and the focal length fG2 of the second lens G2 adjacent to the first lens G1 on the image side. When the first and second lenses G1 and G2 are arranged in order from the object side as negative lenses in the first lens group L1 to widen the angle, if the focal length fG1 of the first lens G1 becomes too short so that fG1 / fG2 falls below the lower limit of equation (6), it becomes difficult to correct field curvature and distortion, which is undesirable. If the focal length fG1 of the first lens G1 becomes long enough so that fG1 / fG2 exceeds the upper limit of equation (6), it is advantageous for aberration correction, but it becomes difficult to achieve both widening the angle and miniaturization. It also tends to lead to an increase in the diameter of the first lens group L1, making it difficult to miniaturize the optical system, which is undesirable.

[0041] Furthermore, it is more preferable to set the lower limit of equation (6) to 0.30, 0.40, 0.45, or 0.48. Also, it is more preferable to set the upper limit of equation (6) to 1.50, 1.40, 1.30, or 1.20.

[0042] The conditions in equation (7) indicate an appropriate relationship between the focal length fLF of the focusing lens group LF and the focal length fw of the entire zoom lens L0 system at the wide-angle end. If the focal length fLF of the focusing lens group LF is shortened so that fLF / fw falls below the lower limit of equation (7), it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, associated with focusing, which is undesirable. If the focal length fLF of the focusing lens group LF is lengthened so that fLF / fw exceeds the upper limit of equation (7), the amount of movement of the focusing lens group LF during focusing becomes longer, making it difficult to miniaturize the optical system, which is also undesirable.

[0043] Furthermore, it is more preferable to set the lower limit of equation (7) to 3.8, 4.0, 4.2, 4.4, 4.6, or 4.8. Also, it is more preferable to set the upper limit of equation (7) to 12.0, 11.0, 10.0, 9.0, 8.1, or 7.9.

[0044] The conditions in equation (8) indicate an appropriate relationship between the focal length fLF of the focusing lens group LF and the focal length fL1 of the first lens group L1. If the focal length fLF of the focusing lens group LF is increased so that fLF / fL1 falls below the lower limit of equation (8), it is undesirable because the amount of movement of the focusing lens group LF during focusing becomes longer, making it difficult to miniaturize the optical system. If the focal length fLF of the focusing lens group LF is shortened so that fLF / fL1 exceeds the upper limit of equation (8), it is undesirable because it becomes difficult to suppress fluctuations in various aberrations, including spherical aberration, associated with focusing.

[0045] Furthermore, it is more preferable to set the lower limit of equation (8) to -4.0, -3.9, -3.8, -3.7, or -3.6. Also, it is more preferable to set the upper limit of equation (8) to -1.9, -2.0, -2.1, or -2.2.

[0046] The conditions in equation (9) indicate an appropriate relationship between the focal length fL1 of the first lens group L1 and the focal length fLPw of the rear lens group LP at the wide-angle end. If the focal length fL1 of the first lens group L1 is increased so that fL1 / fLPw falls below the lower limit of equation (9), the convergence effect in the rear lens group LP increases, which is undesirable because it tends to lead to an increase in the secondary spectra of lateral chromatic aberration and axial chromatic aberration in the rear lens group LP. If the focal length fL1 of the first lens group L1 is shortened so that fL1 / fLPw exceeds the upper limit of equation (9), it is undesirable because it becomes difficult to correct spherical aberration and coma aberration in the rear lens group LP.

[0047] Furthermore, it is more preferable to set the lower limit of equation (9) to -1.2, -1.1, or -1.0. Also, it is more preferable to set the upper limit of equation (9) to -0.45, -0.46, or -0.47.

[0048] The conditions in equation (10) show an appropriate relationship between the air-equivalent distance (back focus) Skw on the optical axis from the image-side lens surface to the image plane IP of the zoom lens L0 at the wide-angle end, and the focal length fw of the entire zoom lens L0 system at the wide-angle end. If the back focus SKw becomes short such that Skw / fw falls below the lower limit of equation (10), it becomes difficult to place optical elements such as low-pass filters near the image sensor on the image plane, which is undesirable. If the back focus SKw becomes long such that Skw / fw exceeds the upper limit of equation (10), the total optical length of the zoom lens L0 at the wide-angle end becomes long, making miniaturization difficult, which is also undesirable.

[0049] Furthermore, it is more preferable to set the lower limit of equation (10) to 1.35, 2.0, 3.0, 4.0, 4.3, or 4.4. Also, it is more preferable to set the upper limit of equation (10) to 5.8, 5.6, 5.4, 5.2, 5.0, 4.9, or 4.8.

[0050] The conditions in equation (11) indicate an appropriate relationship between the optical axis distance DSPw from the aperture diaphragm SP provided in the rear lens group LP to the image-side lens surface of the rear lens group LP (i.e., the zoom lens L0) and the back focus Skw at the wide-angle end. If the distance DSPw becomes shorter so that DSPw / Skw falls below the lower limit of equation (11), it becomes difficult to place the focusing lens group LF within the rear lens group LP, which is undesirable. If the back focus SKw becomes longer so that DSPw / Skw exceeds the upper limit of equation (11), the optical length of the zoom lens L0 at the wide-angle end becomes longer, making it difficult to miniaturize, which is also undesirable.

[0051] Furthermore, it is more preferable to set the lower limit of formula (11) to 0.40, 0.41, or 0.42. Also, it is more preferable to set the upper limit of formula (11) to 2.00, 1.00, 0.85, or 0.79.

[0052] The conditions in equation (12) indicate an appropriate range for the refractive index ndG1 at the d line of the first lens G1, the lens closest to the object in the first lens group L1. Due to the properties of the glass material of the first lens G1, the Abbe number decreases as the refractive index increases, leading to insufficient correction of chromatic aberration. As a result, the refractive power of the first lens G1 must be weakened to suppress chromatic aberration, leading to an increase in the optical length of the zoom lens L0. Furthermore, in retrofocus type zoom lenses, reducing the number of constituent lenses to achieve miniaturization tends to result in a negative Petzval sum, causing the image plane to tilt towards the over-focus side and increasing the astigmatism. For this reason, it is important to appropriately set the refractive index of the first lens G1 as a negative lens to effectively correct image field curvature and astigmatism. If ndG1 falls below the lower limit of equation (12), it is necessary to weaken the refractive power of the negative lens to correct image field curvature, which increases the back focus and makes it difficult to miniaturize the zoom lens L0, thus being undesirable. If ndG1 exceeds the upper limit of equation (12), it is advantageous for correcting field curvature, but it is undesirable because it becomes difficult to correct both distortion and chromatic aberration.

[0053] Furthermore, it is more preferable to set the lower limit of formula (12) to 1.68, 1.71, or 1.74. Also, it is more preferable to set the upper limit of formula (12) to 2.10, 2.06, 2.01, or 1.98.

[0054] The conditions in equation (13) indicate the appropriate shape factor of the first lens G1. R1 is the radius of curvature of the object-side lens surface of the first lens G1, and R2 is the radius of curvature of the image-side lens surface of the first lens G1. If the shape factor (R1+R2) / (R1-R2) falls below the lower limit of equation (13), the refractive power of the first lens G1 becomes too strong, making it difficult to obtain high optical performance, which is undesirable. If the shape factor exceeds the upper limit of equation (13), the refractive power of the first lens G1 becomes too weak, making it difficult to obtain a wide field of view, which is also undesirable.

[0055] Furthermore, it is more preferable to set the lower limit of equation (13) to 1.4, 1.5, 1.6, or 1.7. Also, it is more preferable to set the upper limit of equation (13) to 2.8, 2.7, 2.6, or 2.5.

[0056] The conditions in equation (14) indicate an appropriate relationship between the maximum effective image height Yta at the telephoto end and the maximum effective image height Ywa at the wide-angle end. The maximum effective image height is the distance from the optical axis to the image point furthest from the optical axis among the image points that can be captured by the image sensor or silver halide film. If the maximum effective image height Yta at the telephoto end becomes small enough that Yta / Ywa falls below the lower limit of equation (14), it is undesirable because it becomes difficult to realize a wide-angle zoom lens that includes circular fisheye to diagonal fisheye. If the effective maximum image height Yta at the telephoto end becomes large enough that Yta / Ywa exceeds the upper limit of equation (14), it is undesirable because the amount of movement or refractive force of each lens group that moves during zooming becomes large, making it difficult to suppress variations in aberrations during zooming.

[0057] Furthermore, it is more preferable to set the lower limit of equation (14) to 1.6, 1.7, 1.8, or 1.9. Also, it is more preferable to set the upper limit of equation (14) to 2.8, 2.6, 2.5, 2.3, or 2.1.

[0058] Next, we will describe the configuration that is preferable to satisfy in the zoom lens L0 of each embodiment.

[0059] The first lens group L1 preferably has two or more negative lenses in order from the object side, and the first lens (negative lens) G1 closest to the object has a meniscus shape with a convex surface facing the object side. This facilitates sufficient wide-angle. In this case, if the first lens G1 is held by a lens barrel (not shown), it is preferable that the vertex of the object-side surface of the first lens G1 is located closer to the object than the lens barrel.

[0060] Furthermore, it is preferable that the object-side and image-side lens surfaces of the first lens G1 are spherical. This makes it easier to manufacture zoom lenses while obtaining the necessary optical performance. To further simplify manufacturing, it is preferable that all lenses included in the first lens group L1 be spherical lenses, and that the first lens group L1 be composed of two negative lenses.

[0061] Furthermore, the focusing lens group LF is preferably positioned on the image side of the aperture diaphragm SP and composed of two or fewer lenses. This facilitates miniaturization of the focusing lens group LF and enables faster focusing.

[0062] Furthermore, the rear LP group is preferably composed of three or more lens groups that move such that their spacing from each other changes during zooming. This makes it possible to achieve a sufficient magnification ratio.

[0063] Furthermore, when the half-angle of view at the wide-angle end of the zoom lens L0 in the infinity focus state is ωw(°), 85≦ωw By satisfying these conditions, the necessary field of view for a fisheye zoom lens or ultra-wide-angle zoom lens can be obtained.

[0064] The following shows numerical examples 1 to 7 corresponding to each of Examples 1 to 7. In the surface data of each numerical example, surface number i indicates the order of the optical surfaces when counted from the object side. r is the radius of curvature of the i-th optical surface (mm), d is the lens thickness or air gap on the optical axis between the i-th and (i+1)-th surfaces (mm), and nd is the refractive index of the optical material at the d-line between the i-th and (i+1)-th surfaces. νd is the Abbe number of the optical material at the d-line between the i-th and (i+1)-th surfaces. The Abbe number νd at the d-line is given by Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC, respectively. νd = (Nd-1) / (NF-NC) It is represented by. In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values in the infinity focus state of the zoom lens in each numerical example. BF represents the back focus (mm), and as described above, it is the distance on the optical axis from the lens surface closest to the image side (the final surface) of the zoom lens to the paraxial image plane, expressed in terms of the air equivalent length. The BF at the wide-angle end corresponds to Skw in Equation (10). The overall length of the lens is the length obtained by adding the back focus to the distance on the optical axis from the lens surface closest to the object side of the zoom lens to the final surface, and is also referred to as the overall optical length.

[0065] The "*" attached to the surface number means that the surface has an aspherical shape. The aspherical shape is represented by the following equation when X is the displacement amount from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, the direction of light propagation is positive, R is the paraxial radius of curvature, K is the conic constant, and A4 to A14 are the aspherical coefficients. "e±x" of the conic constant and the aspherical coefficients means ×10 ±x is meant.

[0066] 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 + A14 × h 14 [Numerical Example 1] Unit: mm Surface Data Surface Number r d nd νd 1 48.932 2.00 1.85150 40.8 2 20.284 16.25 3 557.363 1.10 1.80400 46.5 4 28.772 (Variable) 5 34.855 0.90 1.85896 22.7 6 17.068 0.10 1.53344 52.7 7* 17.589 4.70 8 50.857 6.99 1.83400 37.2 9 -20.635 1.05 1.49700 81.7 10 22.129 4.34 11 -16.265 0.80 1.49700 81.7 12 21.161 3.64 1.66565 35.6 13 -55.693 (variable) 14 21.234 3.68 1.63980 34.5 15 -27.788 0.70 1.90043 37.4 16 12.518 4.24 1.59270 35.3 17 -87.908 0.91 18 (aperture) ∞ 2.09 19 42.390 4.09 1.49700 81.7 20 -19.741 (variable) 21 -19.756 0.90 2.00100 29.1 22 -46.915 0.10 1.53344 52.7 23* -32.818 0.25 24 49.974 5.10 1.49700 81.7 25 -15.524 (variable) 26 -39.407 0.70 1.81600 46.6 27 24.127 5.47 1.49700 81.7 28 -23.248 (variable) Image plane ∞ Aspherical data Side 7 K = 0.00000e+00 A 4= 4.48181e-07 A 6= 3.99220e-08 A 8=-9.08985e-11 A10= 1.59194e-12 A12=-4.38981e-15 Page 23 K = 0.00000e+00 A 4= 6.12566e-05 A 6= 1.17826e-07 A 8= 2.22470e-09 A10=-3.70114e-11 A12= 2.37590e-13 Various data Zoom ratio 2.00 Wide-angle, Medium, Telephoto Focal length 6.81 9.58 13.60 F-number 2.85 3.23 3.60 Half-angle (°): 58.57, 57.09, 57.85 Image height 11.15 14.80 21.64 Lens length 127.71 127.71 127.71 BF 30.73 40.08 49.42 d 4 6.34 6.31 2.10 d13 15.72 6.40 1.27 d20 2.33 3.71 3.67 d25 2.47 1.10 1.14 d28 30.73 40.08 49.42 Lens group data Group starting plane focal length 1 1 -16.55 2 5 -42.17 3 14 26.64 4 21 47.74 5 26 -101.75 [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 55.485 2.30 1.85150 40.8 2 19.371 17.05 3 -1103.546 1.30 1.90525 35.0 4 34.645 (variable) 5 37.524 0.90 1.89286 20.4 6 18.491 0.10 1.58946 30.6 7* 18.199 2.37 8 31.026 8.14 1.78880 28.4 9 -20.624 1.10 1.49700 81.7 10 16.423 5.40 11 -14.389 0.80 1.49700 81.7 12 18.091 3.89 1.61340 44.3 13 -39.413 (variable) 14 18.952 4.42 1.53172 48.8 15 -17.614 0.09 16 -17.868 0.70 1.88300 40.8 17 15.902 4.19 1.59270 35.3 18 -41.659 1.44 19 (aperture) ∞ 1.27 20 34.703 4.01 1.49700 81.7 21 -25.217 (variable) 22 -26.388 0.80 1.88300 40.8 23 -78.439 0.10 1.53344 52.7 24* -49.028 0.15 25 31.715 4.97 1.49700 81.7 26 -18.785 (variable) 27 -53.258 0.75 1.88300 40.8 28 19.564 4.78 1.49700 81.7 29 -25.590 (variable) Image plane ∞ Aspherical data Side 7 K = 0.00000e+00 A 4=-9.88827e-06 A 6= 6.80002e-09 A 8=-9.44113e-12 A10= 1.04890e-12 A12=-2.43934e-15 Page 24 K = 0.00000e+00 A 4= 5.68392e-05 A 6= 1.09227e-07 A 8= 3.24013e-10 A10= 1.13582e-12 A12=-2.42531e-14 Various data Zoom ratio 1.97 Wide-angle, Medium, Telephoto Focal length 6.80 9.52 13.41 F-numbers: 2.86, 3.22, 3.61 Half-angle (°): 58.61, 57.24, 58.16 Image height 11.15 14.80 21.60 Lens length 126.11 126.11 126.11 BF 30.90 39.23 47.55 d 4 4.47 5.13 1.29 d13 14.12 5.13 0.65 d21 4.03 3.69 2.74 d26 1.58 1.92 2.87 d29 30.90 39.23 47.55 Lens group data Group starting plane focal length 1 1 -14.82 2 5 -38.96 3 14 27.05 4 22 39.68 5 27 -68.35 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 52.863 2.00 1.85150 40.8 2 19.811 16.64 3 268.068 1.30 2.00100 29.1 4 31.150 (variable) 5 159.698 4.99 1.95375 32.3 6 -30.207 1.20 1.49700 81.7 7 16.611 5.20 8 -17.533 0.80 1.49700 81.7 9 18.643 0.28 10 19.966 6.58 1.78880 28.4 11 -12.466 0.80 2.00100 29.1 12 -61.500 (variable) 13* 55.457 0.10 1.58946 30.6 14 97.068 3.52 1.56732 42.8 15 -14.576 0.05 16 -14.461 0.80 2.00100 29.1 17 22.989 3.89 1.59270 35.3 18 -25.500 0.15 19 52.181 4.70 1.63980 34.5 20 -16.612 0.30 21 (aperture) ∞ (variable) 22 -20.107 0.80 1.95375 32.3 23 -48.225 0.10 1.58946 30.6 24* -37.531 0.15 25 48.217 4.74 1.49700 81.7 26 -16.669 (variable) 27 -101.305 0.80 1.88300 40.8 28 18.672 3.74 1.49700 81.7 29 -30.910 (variable) Image plane ∞ Aspherical data Page 13 K = 0.00000e+00 A 4=-5.40095e-05 A 6=-1.58648e-07 A 8=-6.84435e-09 A10= 1.41530e-10 A12=-1.69897e-12 Page 24 K = 0.00000e+00 A 4= 3.89315e-05 A 6= 1.19235e-07 A 8=-4.99023e-10 A10= 1.75021e-11 A12=-1.12723e-13 Various data Zoom ratio 1.97 Wide-angle, Medium, Telephoto Focal length 6.82 9.56 13.42 F-numbers: 2.83, 3.21, 3.60 Half-angle (°): 58.56, 57.15, 58.14 Image height 11.15 14.80 21.60 Lens length 123.73 123.73 123.73 BF 32.13 40.19 48.25 d 4 7.71 7.34 3.55 d12 13.02 5.32 1.05 d21 5.99 6.19 5.14 d26 1.25 1.05 2.10 d29 32.13 40.19 48.25 Lens group data Group starting plane focal length 1 1 -14.97 2 5 -42.81 3 13 23.42 4 22 53.48 5 27 -82.35 [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 60.163 2.60 1.83481 42.7 2 21.063 12.33 3 109.832 1.50 1.59522 67.7 4 17.672 (variable) 5 150.019 4.20 1.72047 34.7 6 -51.359 1.58 7 -37.627 0.90 1.89190 37.1 8 91.089 2.62 9 -17.827 0.85 1.49700 81.7 10 19.500 0.71 11 24.491 4.63 1.75520 27.5 12 -127.292 (variable) 13* 32.487 0.05 1.58946 30.6 14 24.928 6.44 1.53172 48.8 15 -10.792 0.85 2.00100 29.1 16 -49.566 0.15 17 260.837 3.61 1.59270 35.3 18 -19.964 0.06 19 -83.132 0.90 1.77250 49.6 20 12.974 5.93 1.59270 35.3 21 -21.635 0.87 22 (aperture) ∞ (variable) 23 20.807 4.87 1.49700 81.7 24 -19.178 0.15 25 -22.797 0.80 2.00100 29.1 26 -66.112 (variable) 27 -2019.764 0.80 1.88300 40.8 28 21.543 2.23 29 31.926 3.93 1.49700 81.7 30 -24.775 (variable) Image plane ∞ Aspherical data Page 13 K = 0.00000e+00 A 4= 7.64291e-06 A 6= 4.60507e-07 A 8=-1.46830e-08 A10=3.93238e-10 A12=-3.23460e-12 Various data Zoom ratio 2.06 Wide-angle, Medium, Telephoto Focal length 7.22 10.80 14.86 F-numbers: 2.88, 3.61, 4.12 Half-angle (°): 56.10, 55.97, 55.46 Image height 10.75 16.00 21.60 Lens length 128.99 128.99 128.99 BF 32.52 42.88 49.78 d 4 9.19 8.61 5.93 d12 14.96 5.18 0.95 d22 7.59 6.65 3.60 d26 1.17 2.11 5.15 d30 32.52 42.88 49.78 Lens group data Group starting plane focal length 1 1 -16.14 2 5 -36.44 3 13 35.25 4 23 46.70 5 27 -822.66 [Numerical Example 5] Unit: mm Surface data Face number rd nd νd 1 58.998 2.50 1.76385 48.5 2 15.716 16.74 3 -118.695 1.40 1.59282 68.6 4 37.945 (variable) 5 52.243 3.96 1.66565 35.6 6 -30.668 0.59 7 -22.962 1.00 1.90043 37.4 8 23.854 (variable) 9 23.518 3.91 1.66565 35.6 10 -20.591 1.00 1.49700 81.7 11 22.024 (Variable) 12 18.264 1.00 1.88300 40.8 13 11.917 4.60 1.68430 26.8 14 -39.891 0.15 15 -32.692 1.00 2.05090 26.9 16 17.207 5.02 1.59410 60.5 17 -18.631 0.50 18 (aperture) ∞ (variable) 19 20.545 2.96 1.53775 74.7 20 -202.410 (variable) 21 -60.820 1.28 1.77250 49.6 22* 52.786 0.52 23 80.866 3.72 1.49700 81.7 24 -23.726 0.15 25 -31.425 1.31 1.88300 40.8 26 52.500 3.91 1.49700 81.7 27 -17.095 (variable) Image plane ∞ Aspherical data Page 22 K = 0.00000e+00 A 4= 2.64230e-05 A 6=-4.03358e-09 A 8= 7.40566e-10 A10=-2.79295e-11 A12= 2.33887e-13 Various data Zoom ratio 2.03 Wide-angle, Medium, Telephoto Focal length 7.24 10.93 14.69 F-number 4.10 4.10 4.10 Half-angle (°): 56.05, 55.67, 55.77 Image height 10.75 16.00 21.60 Lens length 127.38 127.38 127.38 BF 32.32 43.68 51.25 d 4 13.34 9.39 4.19 d 8 5.91 6.34 6.60 d11 11.80 3.96 1.33 d18 3.21 3.73 3.00 d20 3.58 3.06 3.79 d27 32.32 43.68 51.25 Lens group data Group starting plane focal length 1 1 -14.79 2 5 -25.40 3 9 64.83 4 12 41.50 5 19 34.85 6 21 -442.01 [Numerical Example 6] Unit: mm Surface data Face number rd nd νd 1 58.154 2.50 1.76385 48.5 2 15.775 16.08 3 -425.603 1.40 1.59282 68.6 4 37.744 (variable) 5 248.610 5.62 1.77047 29.7 6 -19.550 1.00 1.95906 17.5 7 -38.557 (variable) 8 -22.637 1.00 1.91354 36.8 9 28.532 3.85 10 28.132 5.18 1.77047 29.7 11 -21.134 1.00 1.43875 94.7 12 22.654 (variable) 13 24.356 6.32 1.68430 26.8 14 -13.488 1.00 2.00100 29.1 15 28.481 4.91 1.51823 58.9 16 -15.181 0.40 17 (aperture) ∞ (variable) 18 22.580 3.05 1.49700 81.7 19 -104.450 (variable) 20 -34.188 1.28 1.76450 49.1 21* 87.503 2.04 22 32.469 4.26 1.49700 81.7 23 -18.234 0.15 24 -176.617 1.31 1.88300 40.8 25 19.236 3.68 1.49700 81.7 26 -61.995 (variable) Image plane ∞ Aspherical data Page 21 K = 0.00000e+00 A 4= 3.50880e-05 A 6= 1.70964e-08 A 8= 3.91104e-09 A10=-9.58126e-11 A12= 7.92141e-13 Various data Zoom ratio 2.06 Wide-angle, Medium, Telephoto Focal length 7.25 11.01 14.97 F-number 4.10 4.10 4.10 Half-angle (°): 56.00, 55.46, 55.27 Image height 10.75 16.00 21.60 Lens length 131.41 131.41 131.41 BF 32.32 43.52 50.99 d 4 11.62 9.61 3.44 d 7 1.54 1.48 2.68 d12 13.54 4.41 1.90 d17 4.43 4.43 3.35 d19 1.92 1.92 3.00 d26 32.32 43.52 50.99 Lens group data Group starting plane focal length 1 1 -16.36 2 5 54.77 3 8 -23.38 4 13 42.94 5 18 37.66 6 20 -345.10 [Numerical Example 7] Unit: mm Surface data Face number rd nd νd 1 49.099 2.50 1.95375 32.3 2 17.269 18.96 3 -100.783 1.60 1.76385 48.5 4 -8578.672 (variable) 5 481.776 6.91 1.73037 32.2 6 -25.244 1.00 1.95906 17.5 7 -67.981 (variable) 8* -44.668 1.00 1.61881 63.9 9* 16.516 0.99 10 22.668 4.04 1.92286 20.9 11 -262.290 1.00 1.49700 81.5 12 26.016 (Variable) 13 -33.322 1.00 1.80400 46.5 14 -53.867 (variable) 15 42.420 3.92 1.80610 40.7 16 -11.822 1.00 2.00100 29.1 17 -32.854 3.17 18 (aperture) ∞ 0.99 19 60.060 1.76 1.49700 81.5 20 -78.663 6.38 21 46.081 2.49 1.49700 81.5 22 -27.161 (variable) 23* -20.417 1.28 1.88202 37.2 24* -85.455 (variable) 25 28.685 6.28 1.49700 81.5 26 -22.474 0.15 27 -29.239 1.31 2.00069 25.5 28 258.674 3.83 29 56.078 3.06 1.72047 34.7 30 4163.497 (variable) Image plane ∞ Aspherical data Side 8 K = 0.00000e+00 A 4=-1.74583e-05 A 6= 2.76581e-07 A 8=-5.21073e-09 A10= 4.33174e-11 A12=-1.40705e-13 9th page K = 0.00000e+00 A 4=-3.55502e-05 A 6= 3.18165e-07 A 8=-1.08577e-08 A10= 1.25034e-10 A12=-5.41632e-13 Page 23 K = 0.00000e+00 A 4= 3.92865e-04 A 6=-7.05900e-06 A 8= 9.81252e-08 A10=-1.05391e-09 A12= 7.12017e-12 Page 24 K = 0.00000e+00 A 4= 3.85499e-04 A 6=-5.94595e-06 A 8= 6.66907e-08 A10=-4.63906e-10 A12= 1.93438e-12 Various data Zoom ratio 2.04 Wide-angle, Medium, Telephoto Focal length 7.22 11.15 14.71 F-number 4.10 4.10 4.10 Half-angle (°): 56.13, 55.12, 55.74 Image height 10.75 16.00 21.60 Lens length 118.17 118.17 118.17 BF 10.00 19.83 26.38 d 4 4.63 6.38 0.96 d 7 2.05 3.72 6.56 d12 13.07 4.45 3.57 d14 7.36 3.44 0.83 d22 1.90 2.45 3.45 d24 4.55 3.28 1.80 d30 10.00 19.83 26.38 Lens group data Group starting plane focal length 1 1 -21.45 2 5 151.79 3 8 -36.46 4 13 -111.07 5 15 17.56 6 23 -30.70 7 25 70.22 The values ​​for equations (1) to (14) in each numerical example are summarized in Table 1 below. The zoom lens L0 in numerical examples 1 to 6 satisfies all the conditions of equations (1) to (14). In addition, the zoom lens L0 in numerical example 7 satisfies all the conditions of equations (1) to (6) and equations (9) to (14).

[0067] [Table 1]

[0068] Figures 2, 4, 6, 8, 10, 12, and 14 show the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of zoom lens L0 for numerical examples 1 to 7 at infinity focus, respectively. In each figure, (A) shows the longitudinal aberration at the wide-angle end, (B) shows the longitudinal aberration at the intermediate zoom position, and (C) shows the longitudinal aberration at the telephoto end.

[0069] In the spherical aberration diagram, Fno indicates the F number, the solid line shows the spherical aberration at the d line (wavelength 587.6 nm), and the dashed line shows the spherical aberration at the g line (wavelength 435.8 nm). In the astigmatism diagram, the solid line S shows the astigmatism at the sagittal image plane, and the dashed line M shows the astigmatism at the meridional image plane. The distortion diagram shows the distortion at the d line. The chromatic aberration diagram shows the lateral chromatic aberration at the g line. ω is the half-angle of view (°) calculated paraxially. [Imaging device] Figure 15 shows an imaging device (digital still camera) 10 using the zoom lens L0 of Examples 1 to 7 as the imaging optical system. The imaging device 10 comprises a camera body 13, an imaging optical system 11 which is one of the zoom lenses from Examples 1 to 7, and an image sensor element 12 such as a CCD sensor or CMOS sensor that captures the optical image (i.e., the subject) formed by the imaging optical system 11.

[0070] By using a compact zoom lens with good optical performance as the imaging optical system 11, an imaging device 10 capable of producing high-quality images can be provided.

[0071] Furthermore, the output image can be improved in quality by electrically correcting various aberrations such as distortion and chromatic aberration in the image acquired by the image sensor 12.

[0072] Furthermore, an imaging system such as a surveillance camera system may be configured that includes a camera equipped with the zoom lens L0 of each embodiment and a control unit that controls the zoom lens L0.

[0073] The above embodiments include the following configuration.

[0074] (Composition 1) A zoom lens comprising a first lens group with negative refractive power, arranged sequentially from the object side to the image side; an intermediate group with negative refractive power including at least one lens group; and a rear group with positive refractive power including multiple lens groups, wherein the first lens group does not move during zooming, but the spacing between adjacent lens groups changes. At the wide-angle end, the air gap between the intermediate group and the rear group is maximized. The aforementioned intermediate group includes a plurality of negative lenses, The aforementioned rear group includes a group of focus lenses that move during focusing. When the focal length of the first lens group is fL1, and the distance along the optical axis from the lens surface closest to the object in the intermediate group to the lens surface closest to the image in the intermediate group at the wide-angle end is DLNw, -5.0 ≤ DLNw / fL1 ≤ -0.7 A zoom lens characterized by satisfying the following conditions.

[0075] (Configuration 2) When the maximum amount of movement among the multiple lens groups included in the rear group during zooming from the wide-angle end to the telephoto end is defined as MLP, 0.7 ≤ MLP / fL1 ≤ 5.0 A zoom lens according to configuration 1, characterized by satisfying the following conditions. (Composition 3) When the focal length of the zoom lens at the wide-angle end is fw, -3.3 ≤ fL1 / fw ≤ -1.7 A zoom lens according to configuration 1 or 2, characterized by satisfying the following conditions. (Composition 4) When the focal length of the intermediate group at the wide-angle end is fLNw, 2.0 ≤ fLNw / fL1 ≤ 3.5 A zoom lens according to any one of configurations 1 to 3, characterized by satisfying the following conditions. (Composition 5) When the focal length of the first lens closest to the object in the first lens group is fG1, 1.4 ≤ fG1 / fL1 ≤ 3.0 A zoom lens according to any one of configurations 1 to 4, characterized by satisfying the following conditions. (Composition 6) When the focal length of the first lens closest to the object in the first lens group is fG1, and the focal length of the second lens adjacent to the first lens on the image side is fG2, 0.20 ≤ fG1 / fG2 ≤ 1.60 A zoom lens according to any one of configurations 1 to 5, characterized by satisfying the following conditions. (Composition 7) When the focal length of the aforementioned focusing lens group is fLF and the focal length of the zoom lens at the wide-angle end is fw, 3.5 ≤ fLF / fw ≤ 15.0 A zoom lens according to any one of configurations 1 to 6, characterized by satisfying the following conditions. (Composition 8) When the focal length of the aforementioned focusing lens group is fLF, -4.1 ≤ fLF / fL1 ≤ -1.8 A zoom lens according to any one of configurations 1 to 7, characterized by satisfying the following conditions. (Composition 9) When the focal length of the rear group at the wide-angle end is fLPw, -1.3 ≤ fL1 / fLPw ≤ -0.4 A zoom lens according to any one of configurations 1 to 8, characterized by satisfying the following conditions. (Composition 10) When Skw is the air-equivalent distance along the optical axis from the image-side lens surface to the image plane of the zoom lens at the wide-angle end, and fw is the focal length of the zoom lens at the wide-angle end, 1.3 ≤ Skw / fw ≤ 6.0 A zoom lens according to any one of configurations 1 to 9, characterized by satisfying the following conditions. (Composition 11) The aforementioned rear group has an aperture diaphragm, When the distance along the optical axis from the aperture diaphragm to the image-side lens surface of the rear group is DSPw, and the focal length of the zoom lens at the wide-angle end is fw, 0.39 ≤ DSPw / Skw ≤ 2.90 A zoom lens according to any one of configurations 1 to 10, characterized by satisfying the following conditions. (Composition 12) When the refractive index of the first lens closest to the object in the first lens group is ndG1 at the d line, 1.65 ≤ ndG1 ≤ 2.20 A zoom lens according to any one of configurations 1 to 11, characterized by satisfying the following conditions. (Composition 13) The lens closest to the object in the first lens group has a meniscus shape with a convex surface facing the object. When R1 is the radius of curvature of the object-side lens surface of the first lens in the first lens group that is closest to the object, and R2 is the radius of curvature of the image-side lens surface of the first lens, 1.3 ≤ (R1 + R2) / (R1 - R2) ≤ 3.0 A zoom lens according to any one of configurations 1 to 12, characterized by satisfying the following conditions. (Composition 14) When the maximum effective image height at the telephoto end is Yta and the maximum effective image height at the wide-angle end is Ywa, 1.5 ≤ Yta / Ywa ≤ 3.0 A zoom lens according to any one of configurations 1 to 13, characterized by satisfying the following conditions. (Composition 15) The zoom lens according to any one of configurations 1 to 14, characterized in that the first lens group is composed of two negative lenses. (Composition 16) The zoom lens according to any one of configurations 1 to 15, characterized in that the focusing lens group is composed of two or fewer lenses. (Composition 17) The zoom lens according to any one of configurations 1 to 16, characterized in that the rear group includes three or more lens groups that move during zooming. (Composition 18) The zoom lens according to any one of configurations 1 to 17, characterized in that the focusing lens group is arranged on the image side of the aperture diaphragm. (Composition 19) A zoom lens according to any one of configurations 1 to 18, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, arranged in order from the object side to the image side. (Composition 20) A zoom lens according to any one of configurations 1 to 18, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with positive refractive power, and a sixth lens group with negative refractive power, arranged in order from the object side to the image side. (Composition 21) A zoom lens according to any one of configurations 1 to 18, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with positive refractive power, a fifth lens group with positive refractive power, and a sixth lens group with negative refractive power, arranged in order from the object side to the image side. (Composition 22) A zoom lens according to any one of configurations 1 to 18, characterized by being composed of a first lens group L1 with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with negative refractive power, a fifth lens group with positive refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, arranged in order from the object side to the image side. (Composition 23) A zoom lens comprising a first lens group with negative refractive power, arranged sequentially from the object side to the image side; an intermediate group with negative refractive power including at least one lens group; and a rear group with positive refractive power including multiple lens groups, wherein the first lens group does not move during zooming, but the spacing between adjacent lens groups changes. At the wide-angle end, the air gap between the intermediate group and the rear group is maximized. The aforementioned intermediate group includes a plurality of negative lenses, The aforementioned rear group is a zoom lens characterized by including a group of focus lenses that move during focusing. (Composition 24) A zoom lens as described in any one of configurations 1 to 23, An imaging device characterized by having an image sensor that captures an image of a subject through the zoom lens.

[0076] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of symbols]

[0077] L0 Zoom Lens L1 First lens group LN intermediate group LP rear group LF Focus Lens Group

Claims

1. A zoom lens comprising a first lens group with negative refractive power, arranged sequentially from the object side to the image side; an intermediate group with negative refractive power including at least one lens group; and a rear group with positive refractive power including multiple lens groups, wherein the first lens group does not move during zooming, but the spacing between adjacent lens groups changes. At the wide-angle end, the air gap between the intermediate group and the rear group is maximized. The aforementioned intermediate group includes a plurality of negative lenses, The aforementioned rear group includes a group of focus lenses that move during focusing. When the focal length of the first lens group is fL1, and the distance along the optical axis from the lens surface closest to the object in the intermediate group to the lens surface closest to the image in the intermediate group at the wide-angle end is DLNw, -5.0 ≤ DLNw / fL1 ≤ -0.7 A zoom lens characterized by satisfying the following conditions.

2. When the maximum amount of movement among the multiple lens groups included in the rear group during zooming from the wide-angle end to the telephoto end is defined as MLP, 0.7 ≤ MLP / fL1 ≤ 5.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

3. When the focal length of the zoom lens at the wide-angle end is fw, -3.3 ≤ fL1 / fw ≤ -1.7 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

4. When the focal length of the intermediate group at the wide-angle end is fLNw, 2.0 ≤ fLNw / fL1 ≤ 3.5 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

5. When the focal length of the first lens closest to the object in the first lens group is fG1, 1.4 ≤ fG1 / fL1 ≤ 3.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

6. When the focal length of the first lens closest to the object in the first lens group is fG1, and the focal length of the second lens adjacent to the first lens on the image side is fG2, 0.20 ≤ fG1 / fG2 ≤ 1.60 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

7. When the focal length of the aforementioned focusing lens group is fLF and the focal length of the zoom lens at the wide-angle end is fw, 3.5 ≤ fLF / fw ≤ 15.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

8. When the focal length of the aforementioned focusing lens group is fLF, -4.1 ≤ fLF / fL1 ≤ -1.8 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

9. When the focal length of the rear group at the wide-angle end is fLPw, -1.3 ≤ fL1 / fLPw ≤ -0.4 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

10. When Skw is the air-equivalent distance along the optical axis from the image-side lens surface to the image plane of the zoom lens at the wide-angle end, and fw is the focal length of the zoom lens at the wide-angle end, 1.3 ≤ Skw / fw ≤ 6.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

11. The aforementioned rear group has an aperture diaphragm, When the distance along the optical axis from the aperture diaphragm to the image-side lens surface of the rear group is DSPw, and the focal length of the zoom lens at the wide-angle end is fw, 0.39 ≦DSPw / Skw ≦ 2.90 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

12. When the refractive index of the first lens closest to the object in the first lens group is ndG1 at the d line, 1.65 ≤ ndG1 ≤ 2.20 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

13. The lens closest to the object in the first lens group has a meniscus shape with a convex surface facing the object. When R1 is the radius of curvature of the object-side lens surface of the first lens in the first lens group that is closest to the object, and R2 is the radius of curvature of the image-side lens surface of the first lens, 1.3≦(R1+R2) / (R1-R2)≦3.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

14. When Yta is the maximum effective image height at the telephoto end and Ywa is the maximum effective image height at the wide-angle end, 1.5 ≤ Yta / Ywa ≤ 3.0 The zoom lens according to claim 1, characterized in that it satisfies the following conditions.

15. The zoom lens according to claim 1, characterized in that the first lens group is composed of two negative lenses.

16. The zoom lens according to claim 1, characterized in that the focusing lens group is composed of two or fewer lenses.

17. The zoom lens according to claim 1, characterized in that the rear group includes three or more lens groups that move during zooming.

18. The zoom lens according to claim 1, characterized in that the focusing lens group is arranged on the image side of the aperture diaphragm.

19. The zoom lens according to claim 1, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, arranged in order from the object side to the image side.

20. The zoom lens according to claim 1, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with positive refractive power, and a sixth lens group with negative refractive power, arranged in order from the object side to the image side.

21. The zoom lens according to claim 1, characterized in that it is composed of a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with positive refractive power, a fifth lens group with positive refractive power, and a sixth lens group with negative refractive power, arranged in order from the object side to the image side.

22. The zoom lens according to claim 1, characterized in that it is composed of a first lens group L1 with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with negative refractive power, a fifth lens group with positive refractive power, a sixth lens group with negative refractive power, and a seventh lens group with positive refractive power, arranged in order from the object side to the image side.

23. A zoom lens comprising a first lens group with negative refractive power, arranged sequentially from the object side to the image side, an intermediate group with negative refractive power including at least one lens group, and a rear group with positive refractive power including multiple lens groups, wherein the spacing between adjacent lens groups changes. A zoom lens characterized in that the air gap between the intermediate group and the rear group is maximized at the wide-angle end.

24. A zoom lens according to any one of claims 1 to 23, An imaging device characterized by having an image sensor that captures an image of a subject through the zoom lens.

Images