Zoom lens and imaging device having the same

Abstract

To obtain a zoom lens that allows for easy high-speed focusing, minimizes aberration fluctuations during focusing, and easily achieves high optical performance across a wide range of object distances. [Solution] The zoom lens has, in order from the object side, a first lens group L1 having positive refractive power, followed by a subsequent lens group. The subsequent lens group has a first focusing lens group LF1 having negative refractive power, a second focusing lens group LF2 having positive refractive power, and a lens group LR having negative refractive power closest to the image. The spacing between each lens group changes during zooming, satisfying predetermined conditions.

Description

[Technical Field]

[0001] This disclosure relates to a zoom lens and an imaging device having the same, and is suitably used in electronic cameras such as video cameras and digital still cameras, as well as film cameras and broadcast cameras. [Background technology]

[0002] In recent years, imaging optical systems used in imaging devices have been required to have zoom lenses with a high zoom ratio, small and lightweight focusing lens groups, fast focusing speed, and minimal fluctuation in optical performance during focusing. As a zoom lens that satisfies these requirements, a zoom lens is known that is composed of a first lens group with positive refractive power and a rear group containing multiple lens groups, in order from the object side to the image side, with focusing performed by the lens groups other than the first lens group. Patent Document 1 discloses a zoom lens consisting of a first to fourth lens group with positive, positive, negative, and positive refractive powers, in order from the object side to the image side, and a rear group with positive refractive power, with focusing performed by the second lens group. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-198656 [Overview of the project] [Problems that the invention aims to solve]

[0004] Zoom lenses used in imaging devices are strongly required to have a predetermined zoom ratio, be compact as a whole, and have a small and lightweight focusing lens group that exhibits minimal aberration fluctuations during focusing.

[0005] Generally, in an inner-focusing zoom lens that focuses using lens groups other than the first lens group, the effective diameter of the first lens group is smaller compared to a zoom lens that focuses by moving the first lens group, making it easier to miniaturize the entire lens system.

[0006] Furthermore, because it involves moving a small, lightweight lens group, the driving force required for the lens group is small, the complexity of the mechanism and control is relatively low, making manufacturing easier, and it also has features such as rapid focusing.

[0007] However, when selecting the focusing lens group from among the lens groups that make up a zoom lens, if the selection of the focusing lens group is inappropriate, aberration fluctuations will increase during focusing, making it difficult to obtain good optical performance across all object distances.

[0008] To obtain a zoom lens with a predetermined zoom ratio, minimal aberration variation during focusing, and high optical performance across all object distances, it is crucial to appropriately set the number of lens groups and the refractive power of each lens group.

[0009] This disclosure aims to provide a zoom lens that allows for easy high-speed focusing, minimizes aberration fluctuations during focusing, and easily achieves high optical performance across a wide range of object distances. [Means for solving the problem]

[0010] To achieve the above objective, a zoom lens as one aspect of this disclosure has positive refractive power arranged sequentially from the object side to the image side. of Lens group L1 and , subsequent lens group And, consisting , A zoom lens in which the distance between adjacent lens groups changes during zooming, The aforementioned successor lens group is The lens group consists of a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power, arranged in order from the object side to the image side. Negative refractive power of First focusing lens group LF1 and Positive refractive power of Second focus lens group LF2 and , In the aforementioned group of subsequent lenses The closest to the image PlacedNegative refractive power of Lens group LR And, consisting 、 The second lens group L2 is composed of a negative meniscus lens with its convex surface facing the object side, the first focusing lens group LF1 is composed of a biconvex positive lens and a biconcave negative lens arranged in order from the object side to the image side, and the second focusing lens group LF2 is composed of a biconvex positive lens, and during zooming The first lens group L1 is with respect to the image plane Immovable and the subsequent lens group ,most has two or more lens groups that move toward the image side in order from the side object In the positioning, zooming When the focal length of the entire system is ft, the focal length of the first focus lens group LF1 is fF1, and the focal length of the lens group LR is fR, death 、 When focusing from infinity to a near-field object, the first focusing lens group LF1 and the second focusing lens group LF2 move relative to the image plane. at the telephoto end The aforementioned zoom lens of it satisfies the conditional expression: -0.50 < fF1 / ft < -0.20 0.50 < fF1 / fR < 1.40 and is characterized by this.

Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a zoom lens that enables high-speed focusing, has little aberration variation during focusing, and can easily obtain high optical performance over the entire object distance.

Brief Description of the Drawings

[0013] [Figure 1] Lens cross-sectional view when focusing on an infinite object at the wide-angle end (short focal length end) of the zoom lens of Example 1 of the present disclosure [Figure 2] Longitudinal aberration diagram when focusing on an infinite object at the wide-angle end of the zoom lens of Example 1 [Figure 3] Longitudinal aberration diagram when focusing on an infinite object at the telephoto end (long focal length end) of the zoom lens of Example 1 [Figure 4] Longitudinal aberration diagram when focusing on an object at a distance of 700 mm at the wide-angle end of the zoom lens of Example 1 [Figure 5] Longitudinal aberration diagram when focusing on an object at a distance of 700 mm at the telephoto end of the zoom lens of Example 1 [Figure 6]Cross-sectional view of the lens when the zoom lens of Embodiment 2 of this disclosure is in focus on an object at infinity at its wide-angle end. [Figure 7] Longitudinal aberration diagram when the zoom lens of Example 2 is focused on an object at infinity at its wide-angle end. [Figure 8] Longitudinal aberration diagram when the zoom lens of Example 2 is focused on an object at infinity at its telephoto end. [Figure 9] Longitudinal aberration diagram when the zoom lens of Example 2 is focused on an object distance of 700 mm at its wide-angle end. [Figure 10] Longitudinal aberration diagram when the zoom lens of Example 2 is focused on an object distance of 700 mm at its telephoto end. [Figure 11] Cross-sectional view of the lens when the zoom lens of Embodiment 3 of this disclosure is in focus on an object at infinity at its wide-angle end. [Figure 12] Longitudinal aberration diagram when the zoom lens of Example 3 is focused on an object at infinity at its wide-angle end. [Figure 13] Longitudinal aberration diagram when the zoom lens of Example 3 is focused on an object at infinity at its telephoto end. [Figure 14] Longitudinal aberration diagram when the zoom lens of Example 3 is focused on an object at a distance of 700 mm at its wide-angle end. [Figure 15] Longitudinal aberration diagram when the zoom lens of Example 3 is focused on an object distance of 700 mm at its telephoto end. [Figure 16] Cross-sectional view of the lens when the zoom lens of Embodiment 4 of this disclosure is in focus on an object at infinity at its wide-angle end. [Figure 17] Longitudinal aberration diagram when the zoom lens of Example 4 is focused on an object at infinity at its wide-angle end. [Figure 18] Longitudinal aberration diagram when the zoom lens of Example 4 is focused on an object at infinity at its telephoto end. [Figure 19] Longitudinal aberration diagram when the zoom lens of Example 4 is focused on an object at a distance of 700 mm at its wide-angle end. [Figure 20] Longitudinal aberration diagram when the zoom lens of Example 4 is focused on an object distance of 700 mm at its telephoto end. [Figure 21]Cross-sectional view of the lens when the zoom lens of Embodiment 5 of this disclosure is in focus on an object at infinity at its wide-angle end. [Figure 22] Longitudinal aberration diagram when the zoom lens of Example 5 is focused on an object at infinity at its wide-angle end. [Figure 23] Longitudinal aberration diagram when the zoom lens of Example 5 is focused on an object at infinity at its telephoto end. [Figure 24] Longitudinal aberration diagram when the zoom lens of Example 5 is focused on an object at a distance of 700 mm at its wide-angle end. [Figure 25] Longitudinal aberration diagram when the zoom lens of Example 5 is focused on an object distance of 700 mm at its telephoto end. [Figure 26] A cross-sectional view of the lens when the zoom lens of Embodiment 6 of this disclosure is in focus on an object at infinity at its wide-angle end. [Figure 27] Longitudinal aberration diagram when the zoom lens of Example 6 is focused on an object at infinity at its wide-angle end. [Figure 28] Longitudinal aberration diagram when the zoom lens of Example 6 is focused on an object at infinity at its telephoto end. [Figure 29] Longitudinal aberration diagram when the zoom lens of Example 6 is focused on an object distance of 700 mm at its wide-angle end. [Figure 30] Longitudinal aberration diagram when the zoom lens of Example 6 is focused on an object distance of 700 mm at its telephoto end. [Figure 31] Schematic diagram of the main parts of a camera (imaging device) equipped with the optical system of this disclosure. [Modes for carrying out the invention]

[0014] The following describes embodiments of the zoom lens and imaging device having the same according to this disclosure.

[0015] The zoom lens of this disclosure has multiple lens groups, and the spacing between adjacent lens groups changes during zooming. The multiple lens groups include a first lens group with positive refractive power, arranged sequentially from the object side to the image side. Furthermore, it has a successor lens group, which includes a first focusing lens group LF1 with negative refractive power, a second focusing lens group LF2 with positive refractive power, and a lens group LR with negative refractive power closest to the image side.

[0016] Figure 1 is a cross-sectional view of the zoom lens of Embodiment 1 of this disclosure when it is in focus on an object at infinity at its wide-angle end (short focal length end).

[0017] Figure 2 shows the longitudinal aberration when the zoom lens of Example 1 is focused on an object at infinity at its wide-angle end.

[0018] Figure 3 shows the longitudinal aberration when the zoom lens of Example 1 is focused on an object at infinity at its telephoto end (long focal length end).

[0019] Figure 4 shows the longitudinal aberration diagram when the zoom lens of Example 1 is focused on an object at a distance of 700 mm at its wide-angle end.

[0020] Figure 5 shows the longitudinal aberration diagram when the zoom lens of Example 1 is focused on an object at a distance of 700 mm at its telephoto end.

[0021] Example 1 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0022] Figure 6 is a cross-sectional view of the zoom lens of Embodiment 2 of this disclosure when it is in focus on an object at infinity at its wide-angle end.

[0023] Figure 7 shows the longitudinal aberration when the zoom lens of Example 2 is focused on an object at infinity at its wide-angle end.

[0024] Figure 8 shows the longitudinal aberration when the zoom lens of Example 2 is focused on an object at infinity at its telephoto end.

[0025] Figure 9 shows the longitudinal aberration diagram when the zoom lens of Example 2 is focused on an object at a distance of 700 mm at its wide-angle end.

[0026] Figure 10 shows the longitudinal aberration when the zoom lens of Example 2 is focused on an object distance of 700 mm at its telephoto end.

[0027] Example 2 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0028] Figure 11 is a cross-sectional view of the zoom lens of Embodiment 3 of this disclosure when it is in focus on an object at infinity at its wide-angle end.

[0029] Figure 12 shows the longitudinal aberration when the zoom lens of Example 3 is focused on an object at infinity at its wide-angle end.

[0030] Figure 13 shows the longitudinal aberration when the zoom lens of Example 3 is focused on an object at infinity at its telephoto end.

[0031] Figure 14 shows the longitudinal aberration when the zoom lens of Example 3 is focused on an object at a distance of 700 mm at its wide-angle end.

[0032] Figure 15 shows the longitudinal aberration when the zoom lens of Example 3 is focused on an object distance of 700 mm at its telephoto end.

[0033] Example 3 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0034] Figure 16 is a cross-sectional view of the zoom lens of Embodiment 4 of this disclosure when it is in focus on an object at infinity at its wide-angle end.

[0035] Figure 17 shows the longitudinal aberration when the zoom lens of Example 4 is focused on an object at infinity at its wide-angle end.

[0036] Figure 18 shows the longitudinal aberration when the zoom lens of Example 4 is focused on an object at infinity at its telephoto end.

[0037] Figure 19 shows the longitudinal aberration diagram when the zoom lens of Example 4 is focused on an object at a distance of 700 mm at its wide-angle end.

[0038] Figure 20 shows the longitudinal aberration when the zoom lens of Example 4 is focused at an object distance of 700 mm at its telephoto end.

[0039] Example 4 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0040] Figure 21 is a cross-sectional view of the zoom lens of Embodiment 5 of this disclosure when it is in focus on an object at infinity at its wide-angle end.

[0041] Figure 22 shows the longitudinal aberration when the zoom lens of Example 5 is focused on an object at infinity at its wide-angle end.

[0042] Figure 23 shows the longitudinal aberration when the zoom lens of Example 5 is focused on an object at infinity at its telephoto end.

[0043] Figure 24 shows the longitudinal aberration when the zoom lens of Example 5 is focused at an object distance of 700 mm at its wide-angle end.

[0044] Figure 25 shows the longitudinal aberration when the zoom lens of Example 5 is focused at an object distance of 700 mm at its telephoto end.

[0045] Example 5 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0046] Figure 26 is a cross-sectional view of the zoom lens of Embodiment 6 of this disclosure when it is in focus on an object at infinity at its wide-angle end.

[0047] Figure 27 shows the longitudinal aberration when the zoom lens of Example 6 is focused on an object at infinity at its wide-angle end.

[0048] Figure 28 shows the longitudinal aberration when the zoom lens of Example 6 is focused on an object at infinity at its telephoto end.

[0049] Figure 29 shows the longitudinal aberration when the zoom lens of Example 6 is focused on an object at a distance of 700 mm at its wide-angle end.

[0050] Figure 30 shows the longitudinal aberration when the zoom lens of Example 6 is focused at an object distance of 700 mm at its telephoto end.

[0051] Example 6 is a zoom lens with a zoom ratio of 2.74 and an F-number of 2.88.

[0052] Figure 31 is a schematic diagram of the main components of a camera (imaging device) equipped with the optical system of this disclosure.

[0053] The zoom lenses in each embodiment are photographic lens systems used in imaging devices such as video cameras, digital cameras, and silver halide film cameras.

[0054] In the cross-sectional view of the lens, the left side is the object side (front), and the right side is the image side (back). In the cross-sectional view of the lens, i indicates the order of the lens group from the object side, and Li is the i-th lens group.

[0055] SP stands for aperture diaphragm.

[0056] The IP (Image Port) is the image plane. When used in the optical system of a video camera or digital still camera, it is the image plane of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor. In the case of a silver halide film camera, it is the photosensitive surface corresponding to the film plane.

[0057] In the aberration diagram, d and g represent the d-line and g-line, respectively. ΔM and ΔS represent the meridional and sagittal image planes, respectively, while chromatic aberration is represented by the g-line.

[0058] ω is the half-angle, and Fno is the F-number.

[0059] In the following embodiments, the wide-angle end and telephoto end refer to the zoom positions when each lens group is located at the ends of the range in which it can move along the optical axis due to the mechanism.

[0060] The arrows indicate the movement trajectory of each lens group during zooming from the wide-angle end to the telephoto end.

[0061] In Examples 1-6, the IS lens group moves to have a component approximately perpendicular to the optical axis, thereby displacing the image approximately perpendicular to the optical axis and correcting image blur caused by vibration of the entire zoom lens. In other words, it performs vibration isolation. By placing the IS lens group in the fixed LFF group, it becomes possible to reduce the weight of the movable group.

[0062] Next, we will describe features of each embodiment other than those mentioned above.

[0063] In positive-lead type zoom lenses, a key challenge is achieving good optical performance across a wide range of object distances while simultaneously achieving a high magnification ratio and miniaturizing the entire lens system. To solve this problem, it is crucial to appropriately set the refractive power and lens configuration of each lens group, as well as the movement conditions of each lens group during zooming. If these configurations are not set appropriately, it becomes extremely difficult to obtain a zoom lens that maintains a high magnification ratio while possessing high optical performance across the entire zoom range.

[0064] To address the above, this disclosure features a first lens group L1 with positive refractive power, followed by a subsequent lens group, starting from the object side. The subsequent lens group comprises a first focusing lens group LF1 with negative refractive power, a second focusing lens group LF2 with positive refractive power, and a lens group LR with negative refractive power closest to the image. The spacing between each lens group changes during zooming. This allows for the appropriate arrangement of each lens group, resulting in a zoom lens with high optical performance across the entire zoom range.

[0065] More preferably, in a zoom lens having two or more lens groups, the first lens group is fixed relative to the image plane, and the subsequent lens groups move sequentially toward the image side from the object, the following conditions were set. When the focal length of the entire lens system at the telephoto end is ft, the focal length of the first focusing lens group LF1 is fF1, and the focal length of lens group LR is fR, -0.50 <fF1 / ft<-0.20···(1) 0.50 <fF1 / fR<1.40···(2) The conditions are met.

[0066] Condition (1) defines the refractive power of the first focusing lens group LF1. In zoom lenses, appropriately setting the refractive power of the focusing group is important to achieve both a shorter minimum focusing distance and high image quality when focusing on close-up objects. If the refractive power of the focusing lens group LF1 becomes too weak, exceeding the lower limit of condition (1), the amount of movement of LF1 during focusing becomes too large, making rapid focusing difficult. Alternatively, shortening the minimum focusing distance becomes difficult. If the refractive power of the focusing lens group LF1 becomes too strong, exceeding the upper limit of condition (1), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0067] Condition (2) defines the ratio of the refractive power of the first focusing lens group LF1 to that of the final lens group LR. If the refractive power of the focusing lens group LF1 becomes stronger than the lower limit of condition (2), it becomes difficult to suppress the fluctuation of spherical aberration during focusing at the telephoto end. If the refractive power of the lens group LR becomes stronger than the upper limit of condition (2), it becomes difficult to correct pincushion distortion at the telephoto end.

[0068] In the optical system of each embodiment, it is preferable that one or more of the following configurations and conditional equations are satisfied. According to this, the effects corresponding to each configuration and conditional equation can be obtained.

[0069] When the distance between the first focusing lens group LF1 and the second focusing lens group LF2 at the telephoto end at infinity is LF12, and the focal length of the first focusing lens group LF1 is fF1, -0.80 <LF12 / fF1<-0.30···(3) It is best to satisfy the following condition.

[0070] Condition (3) specifies the ratio of the distance between the focusing lens groups LF1 and LF2 at the telephoto end to the refractive power of the first focusing lens group LF1. Satisfying condition (3) makes it possible to shorten the minimum focusing distance at the telephoto end. If the refractive power of the focusing lens group LF1 becomes stronger than the lower limit of condition (3), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end. If the distance between the focusing lens groups becomes narrower than the upper limit of condition (3), there is insufficient space for the focusing lens groups to move, making it difficult to shorten the minimum focusing distance.

[0071] The lens group LFF, positioned adjacent to the object side of the first focusing lens group LF1, is preferably fixed relative to the image plane during zooming. By placing the image stabilization lens group, aperture unit, etc., on this fixed lens group, the mechanical layout becomes easier.

[0072] The LFF lens group should ideally include an image-stabilizing lens group. By placing the image-stabilizing lens group in the LFF lens group, which is located close to the aperture, it becomes easier to correct for changes in field curvature during image stabilization.

[0073] In zooming, it is preferable to have five or fewer moving lens elements. By using a multi-group configuration while appropriately setting fixed groups, spherical aberration fluctuations due to zooming can be suppressed, and the cam layout of the mechanism can be simplified.

[0074] When the focal length of the first lens group is f1 and the focal length of the entire lens system at the wide-angle end is fw, 1.50 <f1 / fw<2.40···(4) It is best to satisfy the following condition.

[0075] Condition (4) specifies the focal length of the first lens group L1. If the refractive power of the first lens group L1 weakens beyond the upper limit of condition (4), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 strengthens beyond the lower limit of condition (4), it becomes difficult to correct spherical aberration at the telephoto end.

[0076] When the focal length of the first lens group is f1 and the focal length of the entire lens system at the telephoto end is ft, 0.50 <f1 / ft<0.90···(5) It is best to satisfy the following condition.

[0077] Condition (5) defines the focal length of the first lens group L1. If the refractive power of the first lens group L1 weakens beyond the upper limit of condition (5), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 strengthens beyond the lower limit of condition (5), it becomes difficult to correct spherical aberration at the telephoto end.

[0078] When the average refractive index of the negative lenses constituting the first focusing lens group is denoted as NF1, 1.65 <NF1<2.00···(6) It is best to satisfy the following condition.

[0079] Conditional equation (6) specifies the average refractive index NF1 of the negative lenses constituting the first focusing lens group. If NF1 exceeds the upper limit of conditional equation (6), it becomes necessary to use highly dispersed glass materials, making it difficult to suppress chromatic aberration fluctuations during focusing. If NF1 exceeds the lower limit of conditional equation (6), it becomes difficult to suppress spherical aberration fluctuations during focusing.

[0080] When VF2 is the average Abbe number of the positive lenses that make up the second focus lens group, 25.0 <VF2<80.0···(7) It is best to satisfy the following condition.

[0081] Condition (7) specifies the average Abbe number VF2 of the positive lenses constituting the second focusing lens group. If VF2 exceeds the upper limit of condition (7), it becomes necessary to use glass material with a low refractive index, making it difficult to suppress spherical aberration fluctuations during focusing. If VF2 exceeds the lower limit of condition (7), it becomes difficult to suppress chromatic aberration fluctuations during focusing.

[0082] When the focal length of the LFF lens group is fFF and the focal length of the entire lens system at the wide-angle end is fw, 0.50 <fFF / fw<3.00···(8) It is best to satisfy the following condition.

[0083] If the refractive power of the LFF lens group weakens beyond the upper limit of condition (8), the subsequent focusing lens group becomes larger, increasing the mass of the focusing lens. This makes rapid focusing difficult. If the refractive power of the LFF lens group strengthens beyond the lower limit of condition (8), correcting spherical aberration at the telephoto end becomes difficult.

[0084] When the focal length of the LFF lens group is fFF and the focal length of the entire lens system at the telephoto end is ft, 0.15 <fFF / ft<1.00···(9) It is best to satisfy the following condition.

[0085] If the refractive power of the LFF lens group weakens beyond the upper limit of condition (9), the subsequent focusing lens group becomes larger, increasing the mass of the focusing lens. This makes rapid focusing difficult. If the refractive power of the LFF lens group strengthens beyond the lower limit of condition (9), correcting spherical aberration at the telephoto end becomes difficult.

[0086] When the focal length of the first focusing lens group LF1 is fF1, and the focal length of the entire lens system at the wide-angle end is fw, -1.30 <fF1 / fw<-0.60···(10) It is best to satisfy the following condition.

[0087] If the refractive power of the LF1 focusing lens group weakens beyond the lower limit of condition (10), the amount of movement of LF1 during focusing becomes too large, making rapid focusing difficult. Alternatively, shortening the minimum focusing distance becomes difficult. If the refractive power of the LF1 focusing lens group strengthens beyond the upper limit of condition (10), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0088] When the focal length of the second focusing lens group LF2 is fF2, and the focal length of the entire lens system at the wide-angle end is fw, 0.50 <fF2 / fw<1.10···(11) It is best to satisfy the following condition.

[0089] If the refractive power of the LF2 focusing lens group weakens beyond the upper limit of condition (11), the amount of movement of LF1 during focusing becomes too large, making rapid focusing difficult. Alternatively, shortening the minimum focusing distance becomes difficult. If the refractive power of the LF2 focusing lens group strengthens beyond the lower limit of condition (11), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0090] When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the entire lens system at the telephoto end is ft, 0.20 <fF2 / ft<0.50···(12) It is best to satisfy the following condition.

[0091] If the refractive power of the focusing lens group LF2 weakens beyond the upper limit of condition (12), the amount of movement of LF1 during focusing becomes too large, making rapid focusing difficult. Alternatively, shortening the minimum focusing distance becomes difficult. If the refractive power of the focusing lens group LF2 strengthens beyond the lower limit of condition (12), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0092] When the focal length of the lens group LR is fR, and the focal length of the entire lens system at the wide-angle end is fw, -1.30 <fR / fw<-0.70···(13) It is best to satisfy the following condition.

[0093] If the refractive power of the LR lens group exceeds the upper limit of condition (13), it becomes difficult to correct distortion at the telephoto end. If the refractive power of the LR lens group exceeds the lower limit of condition (13), it becomes difficult to shorten the overall length of the lens.

[0094] When the focal length of the lens group LR is fR, and the focal length of the entire lens system at the telephoto end is ft, -0.50 <fR / ft<-0.20···(14) It is best to satisfy the following condition.

[0095] If the refractive power of lens group LR exceeds the upper limit of condition (14), it becomes difficult to correct distortion at the telephoto end. If the refractive power of lens group LR exceeds the lower limit of condition (14), it becomes difficult to shorten the overall length of the lens.

[0096] When the back focus at the wide-angle end is skw and the focal length of the lens group LR is fR, -0.70 <skw / fR<-0.30···(15) It is best to satisfy the following condition.

[0097] If the refractive power of lens group LR becomes stronger than the lower limit of condition (15), it becomes difficult to correct distortion at the telephoto end. If the refractive power of lens group LR becomes weaker than the upper limit of condition (15), it becomes difficult to shorten the overall length of the lens.

[0098] When the focal length of the image-stabilizing lens group IS is fIS and the focal length of the entire lens system at the telephoto end is ft, 0.20 <fIS / ft<0.40···(16) It is best to satisfy the following condition.

[0099] If the refractive power of the image-stabilizing lens group IS becomes too strong beyond the lower limit of condition (16), it becomes difficult to correct coma aberration during image stabilization at the telephoto end. If the refractive power of the image-stabilizing lens group IS becomes too weak beyond the upper limit of condition (16), the amount of movement during image stabilization increases, and the outer diameter of the lens becomes larger.

[0100] When the amount of movement of the second lens group from the wide-angle end to the telephoto end is m2, and the focal length of the entire lens system at the wide-angle end is fw, 0.45 <m2 / fw<0.85···(17) It is best to satisfy the following condition.

[0101] If the amount of movement of the second lens group L2 during zooming exceeds the lower limit of condition (17), the refractive power of the second lens group L2 becomes too strong, making it difficult to correct field curvature at the wide-angle end. If the amount of movement of the second lens group L2 during zooming exceeds the upper limit of condition (17), it becomes difficult to reduce the overall length of the lens.

[0102] When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, -4.50 <f1 / f2<-1.50···(18) It is best to satisfy the following condition.

[0103] Conditional equation (18) specifies the ratio of the refractive powers of the first lens group L1 and the second lens group L2. If the refractive power of the first lens group L1 becomes too weak, exceeding the lower limit of conditional equation (18), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 becomes too strong, exceeding the upper limit of conditional equation (18), it becomes difficult to correct spherical aberration at the telephoto end.

[0104] When the focal length of the first lens group L1 is f1 and the focal length of the lens group LFF is fFF, 0.60 <f1 / fFF<3.50···(19) It is best to satisfy the following condition.

[0105] Conditional equation (19) specifies the ratio of the refractive powers of the first lens group L1 and the lens group LFF. If the refractive power of the first lens group L1 becomes too weak, exceeding the upper limit of conditional equation (19), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 becomes too strong, exceeding the lower limit of conditional equation (19), it becomes difficult to correct spherical aberration at the telephoto end.

[0106] When the focal length of the first lens group is f1 and the focal length of the first focusing lens group LF1 is fF1, -3.00 <f1 / fF1<-1.50···(20) It is best to satisfy the following condition.

[0107] Conditional equation (20) defines the ratio of the refractive power of the first lens group L1 and the first focusing lens group LF1. If the refractive power of the first lens group L1 becomes too weak, exceeding the lower limit of conditional equation (20), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 becomes too strong, exceeding the upper limit of conditional equation (20), it becomes difficult to correct spherical aberration at the telephoto end.

[0108] When the focal length of the first lens group is f1 and the focal length of the second focusing lens group LF2 is fF2, 2.00 <f1 / fF2<3.50···(21) It is best to satisfy the following condition.

[0109] Conditional equation (21) specifies the ratio of the refractive powers of the first lens group L1 and the second focusing lens group LF2. If the refractive power of the first lens group L1 becomes too weak, exceeding the upper limit of conditional equation (21), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 becomes too strong, exceeding the lower limit of conditional equation (21), it becomes difficult to correct spherical aberration at the telephoto end.

[0110] When the focal length of the first lens group is f1 and the focal length of the lens group LR is fR, -3.00 <f1 / fR<-1.50···(22) It is best to satisfy the following condition.

[0111] Conditional equation (22) specifies the ratio of the refractive powers of the first lens group L1 and the lens groups LR. If the refractive power of the first lens group L1 becomes too weak, exceeding the lower limit of conditional equation (22), it becomes difficult to shorten the overall length of the lens. If the refractive power of the first lens group L1 becomes too strong, exceeding the upper limit of conditional equation (22), it becomes difficult to correct spherical aberration at the telephoto end.

[0112] When the focal length of the first focusing lens group LF1 is fF1 and the focal length of the second focusing lens group LF2 is fF2, -1.60 <fF1 / fF2<-0.90···(23) It is best to satisfy the following condition.

[0113] If the refractive power of the first focusing lens group LF1 weakens beyond the lower limit of condition (23), the amount of movement of LF1 during focusing becomes too large, making rapid focusing difficult. Alternatively, shortening the minimum focusing distance becomes difficult. If the refractive power of the first focusing lens group LF1 strengthens beyond the upper limit of condition (23), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0114] When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the lens group LR is fR, -1.10 <fF2 / fR<-0.50 ···(24) It is best to satisfy the following condition.

[0115] If the refractive power of the second focusing lens group LF2 weakens beyond the upper limit of condition (24), the amount of movement of the second focusing lens group LF2 during focusing becomes too large, making rapid focusing difficult. Alternatively, it becomes difficult to shorten the minimum focusing distance. If the refractive power of the second focusing lens group LF2 strengthens beyond the lower limit of condition (24), it becomes difficult to suppress spherical aberration fluctuations during focusing at the telephoto end.

[0116] The first lens group preferably has a positive lens that satisfies the following condition.

[0117] 3.00 <d1p<3.40···(25) Here, d1p is the specific gravity of the positive lens.

[0118] By satisfying condition (25), it becomes possible to reduce the weight of the optical system.

[0119] Furthermore, in each embodiment, it is preferable to set the numerical ranges of the aforementioned conditional formulas (1) to (25) as follows.

[0120] -0.47 <fF1 / ft<-0.22···(1a) 0.60 <fF1 / fR<1.30···(2a) -0.70 <LF12 / fF1<-0.35···(3a) 1.60 <f1 / fw<2.30···(4a) 0.55 <f1 / ft<0.85···(5a) 1.68 <NF1<1.95···(6a) 27.0 <VF2<70.0···(7a) 0.60 <fFF / fw<2.70···(8a) 0.18 <fFF / ft<0.95···(9a) -1.20 <fF1 / fw<-0.65···(10a) 0.60 <fF2 / fw<1.00···(11a) 0.22 <fF2 / ft<0.40···(12a) -1.20 <fR / fw<-0.75···(13a) -0.46 <fR / ft<-0.24···(14a) -0.65 <skw / fR<-0.35···(15a) 0.23 <fIS / ft<0.37 ···(16a) 0.50 <m2 / fw<0.80···(17a) -4.20 <f1 / f2<-1.60···(18a) 0.70 <f1 / fFF<3.30···(19a) -2.70 <f1 / fF1<-1.70···(20a) 2.10 <f1 / fF2<3.20···(21a) -2.80 <f1 / fR<-1.60···(22a) -1.50 <fF1 / fF2<-1.00···(23a) -1.00 <fF2 / fR<-0.60···(24a) 3.10 <d1p<3.30···(25a) Furthermore, it is preferable to set the numerical ranges of the aforementioned conditional expressions (1) to (25) as follows.

[0121] -0.42 <fF1 / ft<-0.25···(1b) 0.70 <fF1 / fR<1.20···(2b) -0.65 <LF12 / fF1<-0.40···(3b) 1.70 <f1 / fw<2.20···(4b) 0.60 <f1 / ft<0.80···(5b) 1.71 <NF1<1.90···(6b) 28.0 <VF2<65.0···(7b) 0.65 <fFF / fw<2.50···(8b) 0.22 <fFF / ft<0.90···(9b) -1.15 <fF1 / fw<-0.70···(10b) 0.65 <fF2 / fw<0.90···(11b) 0.24 <fF2 / ft<0.35···(12b) -1.10 <fR / fw<-0.80···(13b) -0.42 <fR / ft<-0.28···(14b) -0.60 <skw / fR<-0.40···(15b) 0.25 <fIS / ft<0.35···(16b) 0.55 <m2 / fw<0.75···(17b) -3.90 <f1 / f2<-1.70···(18b) 0.75 <f1 / fFF<3.10···(19b) -2.50 <f1 / fF1<-1.80···(20b) 2.20 <f1 / fF2<3.00···(21b) -2.60 <f1 / fR<-1.70···(22b) -1.40 <fF1 / fF2<-1.05···(23b) -0.90 <fF2 / fR<-0.65···(24b) 3.15 <d1p<3.25···(25b) As described above, each embodiment makes it possible to provide a zoom lens that allows for easy high-speed focusing, minimizes aberration fluctuations during focusing, and easily achieves high optical performance across a wide range of object distances.

[0122] The numerical Examples 1 to 6 corresponding to Examples 1 to 6 are shown below. In each numerical example, i indicates the order of the surface from the object side, ri indicates the radius of curvature of the i-th (the i-th surface), di indicates the distance between the i-th surface and the i+1-th surface, ndi and νdi indicate the refractive index and Abbe number based on the d line, respectively. f is the focal length, and Fno is the F number.

[0123] (Aspherical data) shows the aspherical coefficients when the aspherical surface is represented by the following equation.

[0124] 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 However, x is the displacement amount from the reference surface in the optical axis direction, h is the height in the direction perpendicular to the optical axis, R is the radius of the base quadric surface, k is the conic constant, and An is the n-th aspherical coefficient. Note that "e±XX" in each aspherical coefficient means "×10± XX ".

[0125] Table 1 shows the relationships between the above conditional expressions and the various numerical values in the numerical examples. [Numerical Example 1] In the lens cross-sectional view of Example 1 in FIG. 1, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with positive refractive power (lens group LFF), L6 is the sixth lens group with negative refractive power (lens group LF1), L7 is the seventh lens group with positive refractive power (lens group LF2), and L8 is the eighth lens group with negative refractive power (lens group LR).

[0126] In Example 1, when zooming from the wide-angle end to the telephoto end, the first lens group L1, the fifth lens group L5, and the eighth lens group L8 are fixed relative to the image plane IP as indicated by the arrows. The second lens group L2 moves toward the image side while increasing its distance from the first lens group L1. The third lens group L3 moves toward the image side while decreasing its distance from the second lens group L2. The fourth lens group L4 moves toward the object side while decreasing its distance from the third lens group L3. The sixth lens group L6 moves toward the image side in a convex trajectory at intermediate focal lengths while increasing its distance from the fifth lens group L5. The seventh lens group L7 moves toward the image side while increasing its distance from the sixth lens group L6. The aperture SP is positioned toward the object side of the fifth lens group L5.

[0127] The IS lens group is a bonded positive lens formed by joining a negative meniscus lens with a convex surface facing the object side and a biconvex positive lens. It moves so that it has a component in a direction approximately perpendicular to the optical axis, displacing the image in a direction approximately perpendicular to the optical axis, thereby correcting image blur when the entire zoom lens vibrates. In other words, it performs vibration isolation. Focusing from infinity to a close-range object is achieved by moving the sixth lens group L6 towards the image side and the seventh lens group L7 towards the object side.

[0128] The first lens group L1 consists, in order from the object side, a bonded positive lens formed by joining a negative meniscus lens with its convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens with its convex surface facing the object side.

[0129] The second lens group L2 consists of, in order from the object side, a negative meniscus lens with its convex surface facing the object, a biconcave negative lens, a positive meniscus lens with its convex surface facing the object, and a biconcave negative lens.

[0130] The third lens group L3 consists of a positive meniscus lens with its convex side facing the object.

[0131] The fourth lens group L4 consists of, in order from the object side, a positive meniscus lens with its convex surface facing the object, and a biconvex positive lens.

[0132] The fifth lens group L5 consists, in order from the object side, of a biconcave negative lens, a negative meniscus lens with a convex surface facing the object side, a bonded positive lens formed by joining a negative meniscus lens with a convex surface facing the object side and a positive lens that is biconvex and has an aspherical surface formed on the image side, and a positive meniscus lens with a convex surface facing the object side.

[0133] The sixth lens group L6 consists of a biconvex positive lens and a biconcave negative lens, in that order from the object side.

[0134] The seventh lens group, L7, consists of biconvex positive lenses.

[0135] The eighth lens group L8 is a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-facing side.

[0136] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 121.459 2.80 2.00100 29.1 67.97 2 90.321 8.62 1.49782 82.6 66.72 3 -837.798 0.10 66.53 4 68.997 7.21 1.43387 95.1 64.54 3.18 5 227.486 (Variable) 63.86 6 51.983 1.90 1.60300 65.4 44.64 7 27.567 9.61 39.10 8 -218.817 1.60 1.49782 82.6 38.69 9 88.334 0.10 37.05 10 35.263 3.73 1.85025 30.1 36.34 11 47.951 6.49 35.45 12 -59.570 1.90 1.49782 82.6 35.39 13 117.292 (Variable) 36.13 14 83.663 2.84 1.94594 18.0 36.91 15 294.361 (Variable) 36.85 16 49.113 4.38 1.49782 82.6 36.98 17 205.903 0.10 36.59 18 86.973 5.12 1.49782 82.6 36.25 19 -109.117 (variable) 35.67 20 (aperture) ∞ 3.50 32.80 21 -77.694 1.80 1.89286 20.4 31.47 22 119.783 1.72 30.82 23 51.154 1.70 1.84666 23.8 30.68 24 36.435 2.00 29.90 25 37.037 1.70 1.80400 46.5 30.27 26 23.458 10.24 1.59349 67.0 29.29 27* -91.431 1.30 28.91 28 49.573 2.47 1.91082 35.2 27.53 29 94.650 (Variable) 26.87 30 1701.770 2.38 1.94594 18.0 24.54 31 -77.800 0.20 24.56 32 -96.316 1.25 1.85026 32.3 24.44 33 38.399 (Variable) 24.31 34 240.381 5.49 1.91082 35.2 37.86 35 -56.074 (variable) 38.14 36* -42.193 1.90 1.58313 59.4 35.23 37 10382.035 (Variable) 36.02 Image plane ∞ Aspherical data Page 27 K = 0.00000e+00 A 4= 2.50477e-06 A 6=-2.09501e-09 A 8= 6.89898e-12 A10=-4.20107e-14 A12= 7.28351e-17 Page 36 K = 0.00000e+00 A 4= 1.18000e-06 A 6= 1.63000e-09 A 8=-7.32000e-12 A10= 2.41000e-14 A12=-2.65000e-17 Various data Zoom ratio 2.74 Wide-angle, Medium, Telephoto Focal length 71.40 117.65 195.76 F-number 2.85 2.88 2.88 Half-angle (°): 16.91, 10.45, 6.33 Image height 21.70 21.70 21.70 Lens length 218.00 218.00 218.00 BF 33.02 33.02 33.02 Variable interval data infinity d 5 1.60 22.81 44.01 d13 25.77 12.55 1.60 d15 21.71 12.00 2.30 d19 1.43 3.15 2.60 d29 3.60 6.49 3.60 d33 26.01 26.71 33.71 d35 10.70 7.12 3.00 d37 33.02 33.02 33.02 Object distance 700mm d 5 1.60 22.81 44.01 d13 25.77 12.55 1.60 d15 21.71 12.00 2.30 d19 1.43 3.15 2.60 d29 5.72 12.63 19.80 d33 21.81 16.30 8.25 d35 12.78 11.39 12.27 d37 33.02 33.02 33.02 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 130.50 18.73 2.52 -9.79 2 6 -38.47 25.33 13.11 -6.99 3 14 122.76 2.84 -0.58 -2.02 4 16 56.96 9.60 2.25 -4.33 5 20 163.46 26.43 38.89 26.24 6 30 -55.23 3.83 2.43 0.32 7 34 50.36 5.49 2.35 -0.55 8 36 -72.06 1.90 0.00 -1.20 Single lens data Lens starting plane, focal length 1 1 -368.53 2 2 164.28 3 4 225.16 4 6 -100.27 5 8 -126.19 6 10 138.09 7 12 -79.08 8 14 122.76 9 16 128.37 10 18 98.07 11 21 -52.56 12 23 -157.93 13 25 -84.28 14 26 32.54 15 28 111.37 16 30 78.70 17 32 -32.15 18 34 50.36 19 36 -72.06 [Numerical Example 2] In the cross-sectional view of the lens in Example 2 of Figure 6, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with negative refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with positive refractive power (lens group LFF), L6 is the sixth lens group with negative refractive power (lens group LF1), L7 is the seventh lens group with positive refractive power (lens group LF2), and L8 is the eighth lens group with negative refractive power (lens group LR).

[0137] In Example 2, when zooming from the wide-angle end to the telephoto end, the first lens group L1, the fifth lens group L5, and the eighth lens group L8 are fixed relative to the image plane IP as indicated by the arrows. The second lens group L2 moves toward the image while increasing its distance from the first lens group L1. The third lens group L3 moves toward the image while decreasing its distance from the second lens group L2. The fourth lens group L4 moves toward the image while decreasing its distance from the third lens group L3. The sixth lens group L6 moves toward the object while decreasing its distance from the fifth lens group L5. The seventh lens group L7 moves toward the image while increasing its distance from the sixth lens group L6. The aperture SP is located in the fifth lens group L5.

[0138] The IS lens group is a bonded positive lens formed by joining a biconvex positive lens and a negative meniscus lens with its convex surface facing the image side. It moves so that it has a component approximately perpendicular to the optical axis, displacing the image approximately perpendicular to the optical axis and correcting image blur when the entire zoom lens vibrates. In other words, it performs vibration isolation. Focusing from infinity to a close-range object is achieved by moving the sixth lens group L6 towards the image side and the seventh lens group L7 towards the object side.

[0139] The first lens group L1 consists, in order from the object side, a bonded positive lens formed by joining a negative meniscus lens with its convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens with its convex surface facing the object side.

[0140] The second lens group L2 consists of a negative meniscus lens with its convex surface facing the object.

[0141] The third lens group L3 consists of a double concave negative lens, a positive meniscus lens with its convex side facing the object, and another double concave negative lens.

[0142] The fourth lens group L4 consists of a positive meniscus lens with its convex surface facing the object.

[0143] The fifth lens group L5 consists, in order from the object side, of a biconvex positive lens, a bonded negative lens formed by joining a biconcave negative lens and a positive meniscus lens with a convex surface facing the object side, a bonded positive lens having a biconvex shape with an aspherical surface formed on the object side and a negative meniscus lens with a convex surface facing the image side, and a biconvex positive lens.

[0144] The sixth lens group L6 consists of a bonded negative lens formed by joining a biconvex positive lens and a biconcave negative lens.

[0145] The seventh lens group, L7, consists of a bonded positive lens formed by joining a biconvex positive lens and a negative meniscus lens with its convex surface facing the image side.

[0146] The eighth lens group L8 is a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-facing side.

[0147] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 137.000 2.80 2.00100 29.1 68.00 2 100.651 7.95 1.49782 82.6 66.89 3 -774.095 0.10 66.73 4 78.021 6.89 1.43387 95.1 65.12 3.18 5 317.489 (Variable) 64.53 6 68.378 1.90 1.95375 32.3 45.11 7 35.367 (variable) 40.92 8 -128.066 1.60 1.49782 82.6 36.78 9 75.372 0.10 35.88 10 47.086 4.34 1.84666 23.8 36.55 11 213.475 3.26 36.30 12 -73.602 1.90 1.49782 82.6 36.26 13 94.530 (Variable) 36.56 14 62.706 3.51 1.90043 37.4 37.30 15 184.141 (Variable) 37.06 16* 56.892 7.37 1.59522 67.7 36.28 17 -101.303 1.82 35.39 18 (aperture) ∞ 3.48 32.80 19 -55.404 1.80 1.73037 32.2 31.93 20 33.571 5.62 1.49782 82.6 30.84 21 85.977 1.46 30.83 22* 62.411 8.55 1.59349 67.0 31.18 23 -40.060 1.70 2.00100 29.1 30.97 24 -58.240 1.30 31.32 25 77.754 3.18 1.59522 67.7 29.97 26 -1196.837 (variable) 29.46 27 2052.455 3.98 2.00100 29.1 27.59 28 -42.814 1.25 1.76385 48.5 27.08 29 37.451 (Variable) 24.77 30 78.535 7.17 1.67003 47.2 36.80 31 -53.054 1.20 1.84666 23.8 36.89 32 -72.733 (variable) 37.15 33* -47.180 1.90 1.51680 64.1 34.95 34 237.574 (variable) 35.55 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-4.93473e-07 A 6= 2.15707e-10 A 8= 5.48540e-13 A10= 1.59466e-16 Page 22 K = 0.00000e+00 A 4=-2.00000e-06 A 6= 8.31000e-10 A 8=-6.83000e-12 A10= 2.63000e-14 A12=-3.55000e-17 Page 33 K = 0.00000e+00 A 4= 1.18000e-06 A 6= 1.63000e-09 A 8=-7.32000e-12 A10= 2.41000e-14 A12=-2.65000e-17 Various data Zoom ratio 2.74 Wide-angle, Medium, Telephoto Focal length 71.40 116.87 195.76 F-number 2.88 2.88 2.88 Half-angle (°): 16.90, 10.52, 6.33 Image height 21.70 21.70 21.70 Lens length 231.00 231.00 231.00 BF 33.67 33.67 33.67 Variable interval data infinity d 5 1.60 30.07 52.49 d 7 16.20 10.16 10.16 d13 35.23 18.14 1.60 d15 16.50 11.17 5.28 d26 3.88 3.70 2.56 d29 27.16 25.76 33.21 d32 10.64 12.21 5.92 d34 33.67 33.67 33.67 Object distance 700mm d 5 1.60 30.07 52.49 d 7 16.20 10.16 10.16 d13 35.23 18.14 1.60 d15 16.50 11.17 5.28 d26 6.13 8.91 16.59 d29 22.37 14.09 3.94 d32 13.18 18.68 21.14 d34 33.67 33.67 33.67 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 140.06 17.74 2.76 -8.90 2 6 -79.03 1.90 2.07 1.07 3 8 -123.19 11.19 10.83 2.54 4 14 104.18 3.51 -0.94 -2.76 5 16 66.02 36.28 18.95 -11.13 6 27 -70.09 5.23 3.07 0.37 7 30 60.61 8.37 2.63 -2.43 8 33 -75.99 1.90 0.21 -1.04 Single lens data Lens starting plane, focal length 1 1 -394.16 2 2 179.46 3 4 236.36 4 6 -79.03 5 8 -95.06 6 10 70.51 7 12 -82.82 8 14 104.18 9 16 62.29 10 19 -28.38 11 20 106.83 12 22 42.43 13 23 -134.49 14 25 122.78 15 27 41.94 16 28 -25.98 17 30 48.31 18 31 -238.26 19 33 -75.99 [Numerical Example 3] In the cross-sectional view of the lens of Example 3 in Figure 11, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with negative refractive power, L6 is the sixth lens group with positive refractive power (lens group LFF), L7 is the seventh lens group with negative refractive power (lens group LF1), L8 is the eighth lens group with positive refractive power (lens group LF2), and L9 is the ninth lens group with negative refractive power (lens group LR).

[0148] In Example 3, when zooming from the wide-angle end to the telephoto end, the first lens group L1, the fourth lens group L4, the sixth lens group L6, and the ninth lens group L9 are fixed with respect to the image plane IP as shown by the arrows. The second lens group L2 moves toward the image side while increasing the distance from the first lens group L1. The third lens group L3 moves toward the image side while decreasing the distance from the second lens group L2. The fifth lens group L5 moves toward the image side while increasing the distance from the fourth lens group L4. The seventh lens group L7 moves toward the image side while increasing the distance from the sixth lens group L6. The eighth lens group L8 moves toward the image side while increasing the distance from the seventh lens group L7. The aperture stop SP is disposed on the object side of the fifth lens group L5.

[0149] The lens group IS is a biconvex positive lens and moves so as to have a component in a direction substantially perpendicular to the optical axis, and corrects image blurring when the entire zoom lens vibrates by displacing an image in a direction substantially perpendicular to the optical axis. That is, anti-vibration is performed. Focusing from infinity to a close object is performed by moving the seventh lens group L7 toward the image side and the eighth lens group L8 toward the object side.

[0150] The first lens group L1 is composed of, in order from the object side, a cemented positive lens formed by cementing a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens having a convex surface facing the object side.

[0151] The second lens group L2 is composed of a negative meniscus lens having a convex surface facing the object side, a biconcave negative lens, a positive meniscus lens having a convex surface facing the object side, and a biconcave negative lens.

[0152] The third lens group L3 is composed of a positive meniscus lens having a convex surface facing the object side.

[0153] The fourth lens group L4 is a biconvex shape and is composed of a positive lens having an aspherical surface formed on the object-side surface.

[0154] The fifth lens group L is composed of, in order from the object side, a cemented negative lens formed by cementing a biconcave negative lens and a biconvex positive lens.

[0155] The sixth lens group L6 consists of, in order from the object side, a negative meniscus lens with its convex surface facing the object, a positive lens with a biconvex shape and an aspherical surface formed on the object-side surface, and a positive meniscus lens with its convex surface facing the object.

[0156] The seventh lens group L7 consists of a positive meniscus lens with its convex surface facing the image side and a negative meniscus lens with its convex surface facing the object side.

[0157] The eighth lens group, L8, is composed of biconvex positive lenses.

[0158] The ninth lens group L9 has a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-side surface and a negative meniscus lens with a convex surface facing the image side.

[0159] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 111.085 2.80 2.00100 29.1 67.97 2 81.526 9.58 1.49782 82.6 66.52 3 -676.575 0.10 66.30 4 72.558 6.74 1.43387 95.1 64.22 3.18 5 235.734 (variable) 63.57 6 61.345 1.90 1.60300 65.4 41.59 7 27.479 8.23 ​​36.43 8 -212.612 1.60 1.49782 82.6 36.10 9 82.213 0.10 35.69 10 37.128 3.97 1.85025 30.1 36.63 11 54.098 6.56 35.86 12 -55.725 1.90 1.49782 82.6 35.83 13 113.246 (Variable) 37.00 14 79.457 3.80 1.94594 18.0 38.10 15 35819.816 (Variable) 38.08 16* 47.418 7.34 1.49782 82.6 37.88 17 -118.294 (variable) 37.30 18 (aperture) ∞ 3.50 32.80 19 -75.291 1.80 1.92286 20.9 31.67 20 47.173 5.63 1.49782 82.6 31.10 21 -121.911 (variable) 31.25 22 99.901 1.70 1.85478 24.8 31.21 23 57.727 2.00 30.82 24* 57.319 6.32 1.59522 67.7 31.28 25 -108.130 1.30 31.15 26 52.563 3.85 1.56732 42.8 30.04 27 1155.445 (variable) 29.40 28 -436.117 2.00 1.94594 18.0 27.33 29 -100.273 0.20 27.33 30 1564.227 1.25 1.83481 42.7 27.02 31 36.302 (Variable) 26.47 32 136.616 4.29 2.00100 29.1 36.81 33 -94.646 (variable) 36.88 34* -77.546 1.90 1.51680 64.1 34.95 35 158.932 4.71 34.70 36 -42.983 1.90 1.56384 60.7 34.71 37 -68.991 (variable) 35.77 Image plane ∞ Aspherical data 16th surface K = 0.00000e+00 A 4=-8.60981e-07 A 6=-2.53069e-10 A 8= 6.55302e-14 A10=-1.20256e-16 24th surface K = 0.00000e+00 A 4=-2.00000e-06 A 6=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​d31 27.18 24.70 30.53 d33 6.68 7.26 3.00 d37 32.40 32.40 32.40 Object distance 700mm d 5 3.14 23.93 44.72 d13 28.68 13.82 1.60 d15 16.79 10.87 2.30 d17 1.42 3.84 5.73 d21 5.71 3.29 1.40 d27 4.86 9.84 16.67 d31 23.09 15.14 5.07 d33 8.95 11.93 15.16 d37 32.40 32.40 32.40 Entrance pupil position 79.12 137.87 226.21 Exit pupil position -70.31 -64.67 -69.16 Front principal point position 100.88 119.06 44.64 Back principal point position -39.00 -80.80 -163.36 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 129.54 19.22 2.82 -9.84 2 6 -34.65 24.25 11.58 -7.26 3 14 84.18 3.80 -0.00 -1.96 4 16 69.01 7.34 1.42 -3.55 5 18 -59.13 10.93 2.86 -5.43 6 22 50.51 15.17 6.91 -3.79 7 28 -66.35 3.45 2.21 0.30 8 32 56.38 4.29 1.28 -0.88 9 34 -67.00 8.51 1.53 -5.63 Single lens data Lens starting plane, focal length 1 1 -321.30 2 2 146.77 3 4 238.61 4 6 -84.33 5 8 -118.88 6 10 125.69 7 12 -74.74 8 14 84.18 9 16 69.01 10 19 -31.21 11 20 69.09 12 22 -163.00 13 24 63.85 14 26 96.95 15 28 137.26 16 30 -44.53 17 32 56.38 18 34 -100.57 19 36 -207.69 [Numerical Example 4] In the cross-sectional view of the lens in Example 4 shown in Figure 16, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with positive refractive power (lens group LFF), L6 is the sixth lens group with negative refractive power (lens group LF1), L7 is the seventh lens group with positive refractive power (lens group LF2), and L8 is the eighth lens group with negative refractive power (lens group LR).

[0160] In Example 4, when zooming from the wide-angle end to the telephoto end, the first lens group L1, the fifth lens group L5, and the eighth lens group L8 are fixed relative to the image plane IP as indicated by the arrows. The second lens group L2 moves toward the image side while increasing its distance from the first lens group L1. The third lens group L3 moves toward the image side while decreasing its distance from the second lens group L2. The fourth lens group L4 moves toward the object side while decreasing its distance from the third lens group L3. The sixth lens group L6 moves toward the image side while increasing its distance from the fifth lens group L5. The seventh lens group L7 moves toward the image side while increasing its distance from the sixth lens group L6. The aperture SP is positioned toward the object side of the fifth lens group L5.

[0161] The IS lens group is a bonded negative lens formed by joining a biconvex positive lens and a negative meniscus lens with its convex surface facing the image side. It moves so that it has a component in a direction approximately perpendicular to the optical axis, displacing the image in a direction approximately perpendicular to the optical axis, thereby correcting image blur when the entire zoom lens vibrates. In other words, it performs vibration isolation. Focusing from infinity to a close-range object is achieved by moving the sixth lens group L6 towards the image side and the seventh lens group L7 towards the object side.

[0162] The first lens group L1 consists, in order from the object side, a bonded positive lens formed by joining a negative meniscus lens with its convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens with its convex surface facing the object side.

[0163] The second lens group L2 consists of a negative meniscus lens with its convex surface facing the object, another negative meniscus lens with its convex surface facing the object, a positive meniscus lens with its convex surface facing the object, and a biconcave negative lens.

[0164] The third lens group L3 consists of a positive meniscus lens with its convex side facing the object.

[0165] The fourth lens group L4 is a biconvex shape and consists of positive lenses with an aspherical surface formed on the object-facing side.

[0166] The sixth lens group L6 consists of, in order from the object side, a bonded negative lens formed by joining a biconcave negative lens and a biconvex positive lens, a negative meniscus lens with its convex surface facing the object side, a bonded positive lens formed by joining a positive lens with a biconvex shape and an aspherical surface formed on the object side, and a negative meniscus lens with its convex surface facing the image side, and a positive meniscus lens with its convex surface facing the object side.

[0167] The seventh lens group L7 consists of a positive meniscus lens with its convex surface facing the image side and a negative meniscus lens with its convex surface facing the object side.

[0168] The eighth lens group L8 has a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-side surface and a negative meniscus lens with a convex surface facing the image side.

[0169] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 132.960 2.80 2.05090 26.9 68.00 2 100.844 7.91 1.49782 82.6 66.87 3 -795.749 0.10 66.70 4 85.694 5.99 1.43387 95.1 65.17 3.18 5 293.624 (Variable) 64.65 6 63.176 1.90 1.60300 65.4 45.40 7 29.935 7.90 40.08 8 708.708 1.60 1.49782 82.6 39.80 9 67.007 0.10 38.16 10 38.237 3.58 1.80000 29.8 37.74 11 50.470 7.00 37.02 12 -59.858 1.90 1.49782 82.6 37.03 13 334.172 (variable) 38.22 14 70.725 3.85 1.94594 18.0 39.77 15 408.940 (Variable) 39.63 16* 47.041 6.74 1.49782 82.6 39.13 17 -273.016 (variable) 38.48 18 (aperture) ∞ 3.50 32.80 19 -97.891 1.80 1.92286 20.9 31.47 20 37.557 6.12 1.49782 82.6 30.61 21 -157.788 1.40 30.78 22 325.716 1.70 1.54814 45.8 30.83 23 73.884 2.00 30.77 24* 60.045 6.62 1.59349 67.0 31.24 25 -82.445 1.70 1.51742 52.4 31.13 26 -101.433 1.30 31.05 27 50.505 3.86 1.51633 64.1 29.95 28 663.351 (variable) 29.32 29 -205.194 1.95 1.94594 18.0 27.25 30 -81.991 0.20 26.98 31 790.466 1.25 1.83481 42.7 25.85 32 36.857 (Variable) 25.45 33 86.577 4.58 2.00100 29.1 36.64 34 -125.184 (variable) 36.63 35* -101.157 1.90 1.51680 64.1 34.68 36 84.734 5.93 34.08 37 -37.518 1.90 1.56384 60.7 34.09 38 -57.580 (variable) 35.30 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-6.41123e-07 A 6=-2.50555e-10 A 8= 5.57919e-14 A10=-1.34139e-16 Page 24 K = 0.00000e+00 A 4=-2.00000e-06 A 6= 8.31000e-10 A 8=-6.83000e-12 A10= 2.63000e-14 A12=-3.55000e-17 Page 35 K = 0.00000e+00 A 4= 1.18000e-06 A 6= 1.63000e-09 A 8=-7.32000e-12 A10= 2.41000e-14 A12=-2.65000e-17 Various data Zoom ratio 2.74 Wide-angle, Medium, Telephoto Focal length 71.40 113.43 195.76 F-number 2.88 2.88 2.88 Half-angle (°): 16.91, 10.83, 6.33 Image height 21.70 21.70 21.70 Lens length 232.32 232.32 232.32 BF 32.40 32.40 32.40 Variable interval data infinity d 5 4.55 28.33 52.11 d13 39.68 17.79 1.60 d15 18.39 13.55 2.30 d17 2.22 5.17 8.83 d28 3.39 4.91 3.74 d32 26.74 23.65 28.92 d34 5.87 7.44 3.33 d38 32.40 32.40 32.40 Object distance 700mm d 5 4.55 28.33 52.11 d13 39.68 17.79 1.60 d15 18.39 13.55 2.30 d17 2.22 5.17 8.83 d28 5.13 9.53 16.29 d32 22.74 14.25 4.22 d34 8.13 12.22 15.48 d38 32.40 32.40 32.40 Entrance pupil position 84.78 147.18 235.25 Exit pupil position -66.84 -63.54 -70.07 Front principal point position 104.81 126.49 57.03 Back principal point position -39.00 -81.03 -163.36 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 150.66 16.80 2.27 -8.70 2 6 -42.76 23.99 11.30 -7.87 3 14 89.90 3.85 -0.41 -2.38 4 16 81.17 6.74 0.67 -3.87 5 18 140.73 30.00 44.20 32.67 6 29 -68.69 3.40 2.03 0.15 7 33 51.69 4.58 0.95 -1.37 8 35 -60.46 9.73 1.95 -6.43 Single lens data Lens starting plane, focal length 1 1 -415.85 2 2 180.32 3 4 276.50 4 6 -96.42 5 8 -148.78 6 10 174.48 7 12 -101.81 8 14 89.90 9 16 81.17 10 19 -29.23 11 20 61.58 12 22 -174.75 13 24 59.57 14 25 -877.96 15 27 105.65 16 29 143.26 17 31 -46.34 18 33 51.69 19 35 -88.91 20 37 -197.74 [Numerical Example 5] In the cross-sectional view of the lens of Example 5 in Figure 21, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with negative refractive power, L4 is the fourth lens group with positive refractive power (lens group LFF), L5 is the sixth lens group with negative refractive power (lens group LF1), L6 is the seventh lens group with positive refractive power (lens group LF2), and L7 is the eighth lens group with negative refractive power (lens group LR).

[0170] In Example 5, when zooming from the wide-angle end to the telephoto end, the first lens group L1 and the fourth lens group L4 are fixed relative to the image plane IP as indicated by the arrows. The second lens group L2 moves toward the image while increasing its distance from the first lens group L1. The third lens group L3 moves toward the image while decreasing its distance from the second lens group L2. The fifth lens group L5 moves toward the object while decreasing its distance from the fourth lens group L4. The sixth lens group L6 moves toward the image while increasing its distance from the fifth lens group L5. The seventh lens group L7 moves toward the image while decreasing its distance from the sixth lens group L6. The aperture SP is located in the fourth lens group L4.

[0171] The IS lens group is a bonded positive lens formed by joining a biconvex positive lens and a negative meniscus lens with its convex surface facing the image side. It moves so that it has a component in a direction approximately perpendicular to the optical axis, displacing the image in a direction approximately perpendicular to the optical axis, thereby correcting image blur when the entire zoom lens vibrates. In other words, it performs vibration isolation. Focusing from infinity to a close-range object is achieved by moving the fifth lens group L5 towards the image side and the sixth lens group L6 towards the object side.

[0172] The first lens group L1 consists, in order from the object side, a bonded positive lens formed by joining a negative meniscus lens with its convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens with its convex surface facing the object side.

[0173] The second lens group L2 consists of a negative meniscus lens with its convex surface facing the object.

[0174] The third lens group L3 consists of a biconcave negative lens, a biconvex positive lens, and a biconcave negative lens.

[0175] The fourth lens group L4 consists of, in order from the object side, a biconvex positive lens, a biconvex positive lens with an aspherical surface formed on the object-side surface, a bonded negative lens formed by joining a biconcave negative lens and a positive meniscus lens with a convex surface facing the object side, a bonded positive lens formed by joining a biconvex positive lens with an aspherical surface formed on the object-side surface and a negative meniscus lens with a convex surface facing the image side, and a positive meniscus lens with a convex surface facing the object side.

[0176] The fifth lens group L5 consists of a biconvex positive lens and a biconcave negative lens, in that order from the object side.

[0177] The sixth lens group, L6, is composed of biconvex positive lenses.

[0178] The seventh lens group L7 is a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-facing side.

[0179] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 149.087 2.80 1.95375 32.3 68.00 2 92.311 8.52 1.49782 82.6 66.81 3 -796.726 0.10 66.71 4 77.528 8.03 1.43387 95.1 65.59 3.18 5 676.413 (Variable) 65.02 6 131.887 1.90 1.85150 40.8 45.40 7 40.622 (variable) 41.21 8 -95.053 1.60 1.49782 82.6 36.22 9 79.383 0.10 37.22 10 56.144 4.85 1.80810 22.8 37.86 11 -1992.297 3.17 37.80 12 -59.985 1.90 1.49782 82.6 37.78 13 999.021 (Variable) 38.58 14 51.043 6.13 1.76385 48.5 39.98 15 -824.389 3.90 39.58 16* 117.018 5.08 1.59522 67.7 37.18 17 -125.822 2.69 36.28 18 (aperture) ∞ 2.96 33.00 19 -70.373 1.80 1.76182 26.5 32.09 20 34.333 3.27 1.49782 82.6 30.56 21 62.214 2.72 30.44 22* 56.609 8.28 1.59349 67.0 30.83 23 -44.366 1.70 1.72825 28.5 30.54 24 -83.107 1.30 30.52 25 96.462 2.46 1.91082 35.2 29.40 26 610.379 (variable) 28.96 27 1255.270 2.21 1.94594 18.0 26.95 28 -110.495 0.20 26.57 29 -358.254 1.25 1.74400 44.8 25.92 30 36.461 (Variable) 24.39 31 86.038 5.71 1.62041 60.3 34.88 32 -64.093 (variable) 35.02 33* -46.765 1.90 1.58313 59.4 34.20 34 250.625 (Variable) 34.86 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-1.58859e-06 A 6=-4.18393e-10 A 8= 5.35143e-13 A10=-4.13737e-16 Page 22 K = 0.00000e+00 A 4=-2.00000e-06 A 6= 8.31000e-10 A 8=-6.83000e-12 A10= 2.63000e-14 A12=-3.55000e-17 Page 33 K = 0.00000e+00 A 4= 1.18000e-06 A 6= 1.63000e-09 A 8=-7.32000e-12 A10= 2.41000e-14 A12=-2.65000e-17 Various data Zoom ratio 2.74 Wide-angle, Medium, Telephoto Focal length 71.40 117.87 195.76 F-number 2.86 2.88 2.88 Half-angle (°): 16.91, 10.43, 6.33 Image height 21.70 21.70 21.70 Lens length 224.80 224.80 224.80 BF 33.63 36.37 32.40 Variable interval data infinity d 5 5.90 32.22 54.46 d 7 24.79 15.30 9.87 d13 35.23 18.42 1.60 d26 3.10 3.83 2.79 d30 26.68 23.55 34.17 d32 8.95 8.61 3.00 d34 33.63 36.37 32.40 Object distance 700mm d 5 5.90 32.22 54.46 d 7 24.79 15.30 9.87 d13 35.23 18.42 1.60 d26 5.49 10.49 19.83 d30 21.92 11.93 3.96 d32 11.31 13.57 16.17 d34 33.63 36.37 32.40 Entrance pupil position 85.82 151.81 232.72 Exit pupil position -55.05 -51.98 -63.59 Front principal point position 99.73 112.41 29.27 Back principal point position -37.77 -81.51 -163.36 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 142.64 19.45 4.27 -8.64 2 6 -69.61 1.90 1.50 0.46 3 8 -187.10 11.62 9.39 1.06 4 14 49.05 42.28 14.84 -24.69 5 27 -76.87 3.66 2.67 0.61 6 31 60.08 5.71 2.05 -1.53 7 33 -67.43 1.90 0.19 -1.01 Single lens data Lens starting plane, focal length 1 1 -260.42 2 2 166.71 3 4 201.01 4 6 -69.61 5 8 -86.63 6 10 67.64 7 12 -113.60 8 14 63.12 9 16 102.66 10 19 -30.07 11 20 148.12 12 22 43.23 13 23 -133.15 14 25 125.50 15 27 107.44 16 29 -44.42 17 31 60.08 18 33 -67.43 [Numerical Example 6] In the cross-sectional view of the lens of Example 6 in Figure 26, L1 is the first lens group with positive refractive power, L2 is the second lens group with negative refractive power, L3 is the third lens group with positive refractive power, L4 is the fourth lens group with positive refractive power, L5 is the fifth lens group with negative refractive power, L6 is the sixth lens group with positive refractive power (lens group LFF), L7 is the seventh lens group with negative refractive power (lens group LF1), L8 is the eighth lens group with positive refractive power (lens group LF2), and L9 is the ninth lens group with negative refractive power (lens group LR).

[0180] In Example 6, when zooming from the wide-angle end to the telephoto end, the first lens group L1, the fourth lens group L4, the sixth lens group L6, and the ninth lens group L9 are fixed relative to the image plane IP as indicated by the arrows. The second lens group L2 moves toward the image side while increasing its distance from the first lens group L1. The third lens group L3 moves toward the image side while decreasing its distance from the second lens group L2. The fifth lens group L5 moves toward the image side while increasing its distance from the fourth lens group L4. The seventh lens group L7 moves toward the image side while increasing its distance from the sixth lens group L6. The eighth lens group L8 moves toward the image side while increasing its distance from the seventh lens group L7. The aperture SP is positioned on the object side of the fifth lens group L5.

[0181] The IS lens group is a bonded positive lens formed by joining a biconvex positive lens and a negative meniscus lens with its convex surface facing the image side. It moves so that it has a component approximately perpendicular to the optical axis, displacing the image approximately perpendicular to the optical axis and correcting image blur when the entire zoom lens vibrates. In other words, it performs vibration isolation. Focusing from infinity to close-range objects is achieved by moving the 7th lens group L7 towards the image side and the 8th lens group L8 towards the object side.

[0182] The first lens group L1 consists, in order from the object side, a bonded positive lens formed by joining a negative meniscus lens with its convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens with its convex surface facing the object side.

[0183] The second lens group L2 consists of a negative meniscus lens with a convex surface facing the object, a biconcave negative lens, a positive meniscus lens with a convex surface facing the object, and a biconcave negative lens.

[0184] The third lens group L3 consists of a positive meniscus lens with its convex side facing the object.

[0185] The fourth lens group L4 is a biconvex shape and consists of positive lenses with an aspherical surface formed on the object-facing side.

[0186] The fifth lens group L5 consists of a bonded negative lens formed by joining a biconcave negative lens and a biconvex positive lens, in order from the object side.

[0187] The sixth lens group L6 consists of, in order from the object side, a negative meniscus lens with its convex surface facing the object side, a bonded positive lens which is biconvex in shape and is formed by joining a positive lens with an aspherical surface on the object side and a negative meniscus lens with its convex surface facing the image side, and a positive meniscus lens with its convex surface facing the object side.

[0188] The seventh lens group L7 consists of a positive meniscus lens with its convex surface facing the image side and a negative meniscus lens with its convex surface facing the object side.

[0189] The eighth lens group, L8, is composed of biconvex positive lenses.

[0190] The ninth lens group L9 has a biconcave shape and consists of a negative lens with an aspherical surface formed on the object-side surface and a negative meniscus lens with a convex surface facing the image side.

[0191] Unit: mm Surface data Face number rd nd νd Effective diameter d 1 120.460 2.80 2.00100 29.1 67.97 2 88.255 8.78 1.49782 82.6 66.68 3 -857.761 0.10 66.49 4 81.090 6.19 1.43387 95.1 64.83 3.18 5 269.019 (Variable) 64.27 6 64.989 1.90 1.60300 65.4 45.40 7 29.986 8.80 40.01 8 -323.253 1.60 1.49782 82.6 39.70 9 84.536 0.10 38.21 10 39.946 4.03 1.78880 28.4 37.50 11 60.668 8.91 36.72 12 -62.000 1.90 1.49782 82.6 36.54 13 144.884 (variable) 37.52 14 83.085 3.62 1.94594 18.0 38.55 15 1856.086 (Variable) 38.49 16* 49.278 7.08 1.49782 82.6 38.11 17 -131.074 (variable) 37.52 18 (aperture) ∞ 3.50 32.80 19 -83.526 1.80 1.92286 20.9 31.56 20 43.598 5.75 1.49782 82.6 30.85 21 -131.505 (variable) 30.98 22 285.246 1.70 1.61340 44.3 30.93 23 71.464 2.00 30.77 24* 58.177 6.66 1.59349 67.0 31.31 25 -85.177 1.70 1.62004 36.3 31.18 26 -102.863 1.30 31.12 27 58.089 3.22 1.71300 53.9 30.00 28 287.209 (variable) 29.41 29 -464.061 1.98 1.94594 18.0 27.94 30 -105.816 0.20 27.94 31 716.524 1.25 1.83481 42.7 27.62 32 36.578 (Variable) 27.04 33 129.329 4.31 2.00100 29.1 37.18 34 -100.318 (variable) 37.23 35* -90.226 1.90 1.51680 64.1 35.20 36 126.152 5.31 34.84 37 -39.936 1.90 1.56384 60.7 34.84 38 -60.572 (variable) 35.97 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-6.32855e-07 A 6=-2.09233e-10 A 8=-5.55430e-14 A10= 2.02396e-17 Page 24 K = 0.00000e+00 A 4=-2.00000e-06 A 6= 8.31000e-10 A 8=-6.83000e-12 A10= 2.63000e-14 A12=-3.55000e-17 Page 35 K = 0.00000e+00 A 4= 1.18000e-06 A 6= 1.63000e-09 A 8=-7.32000e-12 A10= 2.41000e-14 A12=-2.65000e-17 Various data Zoom ratio 2.74 Wide-angle, Medium, Telephoto Focal length 71.40 113.32 195.76 F-number 2.84 2.88 2.88 Half-angle (°): 16.91, 10.84, 6.33 Image height 21.70 21.70 21.70 Lens length 232.32 232.32 232.32 BF 32.40 32.40 32.40 Variable interval data infinity d 5 3.19 26.77 50.35 d13 34.04 16.35 1.60 d15 17.78 11.88 3.05 d17 1.89 4.26 6.24 d21 5.75 3.37 1.40 d28 3.31 5.04 3.34 d32 26.89 24.86 30.65 d34 6.79 7.09 3.00 d38 32.40 32.40 32.40 Object distance 700mm d 5 3.19 26.77 50.35 d13 34.04 16.35 1.60 d15 17.78 11.88 3.05 d17 1.89 4.26 6.24 d21 5.75 3.37 1.40 d28 5.24 10.11 16.90 d32 22.68 15.10 5.03 d34 9.06 11.78 15.06 d38 32.40 32.40 32.40 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 144.25 17.86 2.49 -9.24 2 6 -40.03 27.24 12.88 -8.69 3 14 91.86 3.62 -0.09 -1.95 4 16 72.89 7.08 1.31 -3.48 5 18 -59.63 11.05 2.96 -5.40 6 22 51.99 16.58 8.20 -3.25 7 29 -68.37 3.43 2.23 0.33 8 33 56.97 4.31 1.23 -0.95 9 35 -68.17 9.11 1.66 -6.11 Single lens data Lens starting plane, focal length 1 1 -344.79 2 2 161.24 3 4 264.91 4 6 -94.25 5 8 -134.43 6 10 136.54 7 12 -86.95 8 14 91.86 9 16 72.89 10 19 -30.83 11 20 66.50 12 22 -155.92 13 24 59.27 14 25 -829.49 15 27 101.53 16 29 144.52 17 31 -46.21 18 33 56.97 19 35 -101.48 20 37 -215.03 Table 1 JPEG0007851473000002.jpg200157

[0192] Furthermore, in the zoom lenses of each embodiment, it is preferable to deposit a fluorine coating on the object-side lens surface of the lens positioned closest to the object and on the image-side lens surface of the lens positioned closest to the image. Since the object-side lens surface of the lens positioned closest to the object and the image-side lens surface of the lens positioned closest to the image are more susceptible to external exposure, depositing a fluorine coating enhances water and oil repellency, suppresses flare, and allows for high optical performance. In particular, since the object-side lens surface of the lens positioned closest to the object has a large diameter, it is preferable to deposit a fluorine coating there.

[0193] In the cemented lenses arranged in the zoom lenses of each embodiment, it is preferable that the positive and negative lenses constituting at least one cemented lens are bonded together with an adhesive having a thickness of 0.005 mm or more and 0.05 mm or less along the optical axis. If it is less than 0.005 mm, it is prone to peeling, and if it is greater than 0.05 mm, the distance along the optical axis from the lens surface closest to the object to the lens surface closest to the image becomes longer, thus increasing the overall length of the lens. It is more preferable to satisfy the condition of 0.008 mm or more and 0.02 mm or less.

[0194] At least one lens arranged in the zoom lens of each embodiment is coated with an anti-reflective coating to prevent reflection, and the anti-reflective coating is composed of multiple films. Here, it is preferable that the anti-reflective coating PC has a refractive index of 1.32 or less when Nd is the refractive index of the film closest to the air interface with respect to the d line. By setting Nd to 1.32 or less, the refractive index difference with air can be reduced, making it possible to further reduce light reflection and reduce ghosting.

[0195] Specific examples of the configuration of the anti-reflective coating PC include, but are not limited to, the multilayer film using the wet method described in Japanese Patent Publication No. 2012-230211 and Japanese Patent Publication No. 2014-95877. More preferably, ghosting can be further reduced by setting Nd to 1.30 or less.

[0196] In this case, it is preferable to apply an anti-reflective coating PC to the image-side lens surface of the negative lens with its concave surface facing the image side, among the negative lenses arranged in the zoom lens. Light reflected by a negative lens with its concave surface facing the image side tends to be reflected at a large angle with respect to the normal direction of the lens surface of the negative lens with its concave surface facing the image side, so the reflectivity tends to be high. Also, light reflected by a negative lens with its concave surface facing the image side tends to be focused at the image plane, so ghosting is likely to be noticeable. Therefore, by applying an anti-reflective coating PC to the image-side lens surface of a negative lens with its concave surface facing the image side, ghosting can be reduced.

[0197] Next, an embodiment using the zoom lens of this disclosure as an imaging optical system will be described with reference to Figure 31. In Figure 31, 10 is a diagram of an example of an imaging device, 11 is an imaging optical system composed of the zoom lens of this disclosure, and 12 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor that receives the subject image formed by the imaging optical system 11. Also, 13 is a recording means for recording the subject image received by the image sensor 12, and 14 is a viewfinder for observing the subject image displayed on an unshown display element. The display element is composed of a liquid crystal panel or the like, and displays the subject image formed on the image sensor 12.

[0198] By applying the zoom lens of this disclosure to optical equipment such as digital cameras, optical equipment with high optical performance can be realized.

[0199] Furthermore, this disclosure can also be applied to SLR (Single-lens Reflex) cameras without a quick-return mirror.

[0200] Furthermore, the zoom lens described herein can also be applied to video cameras.

[0201] This embodiment includes the following configuration. (Composition 1) In a zoom lens having two or more lens groups, arranged sequentially from the object side to the image side, a first lens group L1 having positive refractive power, and a subsequent lens group, the subsequent lens group having a first focusing lens group LF1 having negative refractive power, a second focusing lens group LF2 having positive refractive power, and a lens group LR having negative refractive power closest to the image side, the spacing between each lens group changes during zooming, the first lens group L1 is fixed relative to the image plane, and the subsequent lens groups move sequentially from the object towards the image side, when the focal length of the entire lens system at the telephoto end is ft, the focal length of the first focusing lens group LF1 is fF1, and the focal length of the lens group LR is fR, -0.50 <fF1 / ft<-0.20 0.50 <fF1 / fR<1.40 A zoom lens characterized by satisfying the following conditional equation. (Configuration 2) When the distance between the first focusing lens group LF1 and the second focusing lens group LF2 at the telephoto end at infinity is LF12, and the focal length of the first focusing lens group LF1 is fF1, -0.80 <LF12 / fF1<-0.30 A zoom lens according to configuration 1, characterized in that it satisfies the following condition. (Composition 3) The zoom lens according to configuration 1 or 2, characterized in that the lens group LFF, which is positioned adjacent to the object side of the first focus lens group LF1, is fixed with respect to the image plane during zooming. (Composition 4) The zoom lens according to any one of configurations 1 to 3, characterized in that the lens group LFF, which is arranged adjacent to the object side of the first focus lens group LF1, has an image stabilization lens group. (Composition 5) A zoom lens according to any one of configurations 1 to 4, characterized in that the number of moving lens groups is 5 or less during zooming. (Composition 6) When the focal length of the first lens group L1 is f1 and the focal length of the entire lens system at the wide-angle end is fw, 1.50 <f1 / fw<2.40 A zoom lens according to any one of the configurations 1 to 5, characterized in that it satisfies the following condition. (Composition 7) When the focal length of the first lens group L1 is f1 and the focal length of the entire lens system at the telephoto end is ft, 0.50 <f1 / ft<0.90 A zoom lens according to any one of the configurations 1 to 6, characterized in that it satisfies the following conditional expression. (Composition 8) When the average refractive index of the negative lenses constituting the first focus lens group LF1 is denoted as NF1, 1.65 <NF1<2.00 A zoom lens according to any one of configurations 1 to 7, characterized by satisfying the following conditional expression. (Composition 9) When the average Abbe number of the positive lenses constituting the second focus lens group LF2 is VF2, 25.0 <VF2<80.0 A zoom lens according to any one of the configurations 1 to 8, characterized in that it satisfies the following conditional expression. (Composition 10) When the focal length of the lens group LFF, which is positioned adjacent to the object side of the first focusing lens group LF1, is fFF, and the focal length of the entire lens system at the wide-angle end is fw, 0.50 <fFF / fw<3.00 A zoom lens according to any one of the configurations 1 to 9, characterized in that it satisfies the following condition. (Composition 11) When the focal length of the lens group LFF, which is positioned adjacent to the object side of the first focusing lens group LF1, is fFF, and the focal length of the entire lens system at the telephoto end is ft, 0.15 <fFF / ft<1.00 A zoom lens according to any one of the configurations 1 to 10, characterized by satisfying the following conditional expression. (Composition 12) When the focal length of the first focusing lens group LF1 is fF1 and the focal length of the entire lens system at the wide-angle end is fw, -1.30 <fF1 / fw<-0.60 A zoom lens according to any one of the configurations 1 to 11, characterized by satisfying the following conditional expression. (Composition 13) When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the entire lens system at the wide-angle end is fw, 0.50 <fF2 / fw<1.10 A zoom lens according to any one of the configurations 1 to 12, characterized by satisfying the following conditional expression. (Composition 14) When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the entire lens system at the telephoto end is ft, 0.20 <fF2 / ft<0.50 A zoom lens according to any one of the configurations 1 to 13, characterized by satisfying the following conditional expression. (Composition 15) When the focal length of the lens group LR is fR, and the focal length of the entire lens system at the wide-angle end is fw, -1.30 <fR / fw<-0.70 A zoom lens according to any one of the configurations 1 to 14, characterized by satisfying the following conditional expression. (Composition 16) When the focal length of the lens group LR is fR and the focal length of the entire lens system at the telephoto end is ft, -0.50 <fR / ft<-0.20 A zoom lens according to any one of the configurations 1 to 15, characterized by satisfying the following conditional expression. (Composition 17) When the back focus at the wide-angle end is skw and the focal length of the lens group LR is fR, -0.70 <skw / fR<-0.30 A zoom lens according to any one of the configurations 1 to 16, characterized in that it satisfies the following condition. (Composition 18) When the focal length of the image-stabilizing lens group IS is fIS and the focal length of the entire lens system at the telephoto end is ft, 0.20 <fIS / ft<0.40 A zoom lens according to any one of the configurations 1 to 17, characterized by satisfying the following conditional expression. (Composition 19) When the amount of movement of the second lens group L2 from the wide-angle end to the telephoto end is m2, and the focal length of the entire lens system at the wide-angle end is fw, 0.45 <m2 / fw<0.85 A zoom lens according to any one of the configurations 1 to 18, characterized by satisfying the following conditional expression. (Composition 20) When the focal length of the first lens group L1 is f1 and the focal length of the second lens group L2 is f2, -4.50 <f1 / f2<-1.50 A zoom lens according to any one of the configurations 1 to 19, characterized by satisfying the following conditional expression. (Composition 21) When the focal length of the first lens group L1 is f1, and the focal length of the lens group LFF, which is positioned adjacent to the object side of the first focusing lens group LF1, is fFF, 0.60 <f1 / fFF<3.50 A zoom lens according to any one of the configurations 1 to 20, characterized by satisfying the following conditional expression. (Composition 22) When the focal length of the first lens group L1 is f1 and the focal length of the first focusing lens group LF1 is fF1, -3.00 <f1 / fF1<-1.50 A zoom lens according to any one of the configurations 1 to 21, characterized by satisfying the following conditional expression. (Composition 23) When the focal length of the first lens group L1 is f1 and the focal length of the second focusing lens group LF2 is fF2, 2.00 <f1 / fF2<3.50 A zoom lens according to any one of the configurations 1 to 22, characterized by satisfying the following conditional expression. (Composition 24) When the focal length of the first lens group L1 is f1 and the focal length of the lens group LR is fR, -3.00 <f1 / fR<-1.50 A zoom lens according to any one of the configurations 1 to 23, characterized by satisfying the following conditional expression. (Composition 25) When the focal length of the first focusing lens group LF1 is fF1 and the focal length of the second focusing lens group LF2 is fF2, -1.60 <fF1 / fF2<-0.90 A zoom lens according to any one of the configurations 1 to 24, characterized by satisfying the following conditional expression. (Composition 26) When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the lens group LR is fR, -1.10 <fF2 / fR<-0.50 A zoom lens according to any one of the configurations 1 to 25, characterized by satisfying the following conditional expression. (Composition 27) The zoom lens according to any one of configurations 1 to 26, characterized in that the first lens group L1 has a positive lens that satisfies the following condition.

[0202] 3.00 <d1p<3.40 d1p: Specific gravity of the positive lens (Composition 28) A zoom lens characterized by having a first lens group L1 with positive refractive power and a subsequent lens group arranged sequentially from the object side to the image side, wherein the subsequent lens group comprises a first focusing lens group LF1 with negative refractive power, a second focusing lens group LF2 with positive refractive power, and a lens group LR with negative refractive power closest to the image side, and the spacing between each lens group changes during zooming. (Composition 29) An imaging device characterized by having a zoom lens according to any one of configurations 1 to 28, and a solid-state image sensor that receives the image formed by the zoom lens.

[0203] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence. [Explanation of symbols]

[0204] L1 First lens group LF1 First Focusing Lens Group LF2 Second Focusing Lens Group LR: Lens group positioned closest to the image sensor IP image plane

Claims

1. A zoom lens consisting of a first lens group L1 with positive refractive power and a subsequent lens group, arranged sequentially from the object side to the image side, wherein the distance between adjacent lens groups changes during zooming. The aforementioned successor lens group consists of a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, a first focusing lens group LF1 with negative refractive power, a second focusing lens group LF2 with positive refractive power, and a negative refractive power lens group LR located furthest towards the image side in the aforementioned successor lens group. The second lens group L2 is composed of a negative meniscus lens with a convex surface facing the object side. The first focusing lens group LF1 is composed of a biconvex positive lens and a biconcave negative lens, arranged in order from the object side to the image side. The second focusing lens group LF2 is composed of biconvex positive lenses. During zooming, the first lens group L1 remains stationary with respect to the image plane. The aforementioned successor lens group has two or more lens groups that are arranged in order from the object side and move toward the image side during zooming. When focusing from infinity to a near-field object, the first focusing lens group LF1 and the second focusing lens group LF2 move relative to the image plane. When the total focal length of the zoom lens system at the telephoto end is ft, the focal length of the first focusing lens group LF1 is fF1, and the focal length of the lens group LR is fR, -0.50<fF1 / ft<-0.20 0.50<fF1 / fR<1.40 A zoom lens characterized by satisfying the following conditional equation.

2. When the distance between the first focusing lens group LF1 and the second focusing lens group LF2 on the optical axis at infinity and the telephoto end is LF12, and the focal length of the first focusing lens group LF1 is fF1, -0.80<LF12 / fF1<-0.30 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. The zoom lens according to claim 1, characterized in that the lens group LFF, which is arranged adjacent to the object side of the first focusing lens group LF1, is immovable with respect to the image plane during zooming.

4. The zoom lens according to claim 1, characterized in that the lens group LFF, which is arranged adjacent to the object side of the first focusing lens group LF1, has an image stabilization lens group.

5. The zoom lens according to claim 1, characterized in that the number of lens groups that move relative to the image plane during zooming is five or less.

6. When the focal length of the first lens group L1 is f1 and the total focal length of the zoom lens system at the wide-angle end is fw, 1.50<f1 / fw<2.40 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the first lens group L1 is f1 and the total focal length of the zoom lens system at the telephoto end is ft, 0.50<f1 / ft<0.90 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

8. When NF1 is the average refractive index of the materials of all the negative lenses constituting the first focus lens group LF1, 1.65<NF1<2.00 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

9. When VF2 is the average of the Abbe numbers of the materials of all the positive lenses constituting the second focus lens group LF2, 25.0<VF2<80.0 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

10. When the focal length of the lens group LFF, which is arranged adjacent to the object side of the first focusing lens group LF1, is fFF, and the focal length of the entire zoom lens system at the wide-angle end is fw, 0.50<fFF / fw<3.00 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

11. When the focal length of the lens group LFF, which is arranged adjacent to the object side of the first focusing lens group LF1, is fFF, and the total focal length of the zoom lens system at the telephoto end is ft, 0.15<fFF / ft<1.00 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

12. When the focal length of the first focusing lens group LF1 is fF1 and the total focal length of the zoom lens system at the wide-angle end is fw, -1.30<fF1 / fw<-0.60 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

13. When the focal length of the second focusing lens group LF2 is fF2, and the total focal length of the zoom lens system at the wide-angle end is fw, 0.50<fF2 / fw<1.10 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

14. When the focal length of the second focusing lens group LF2 is fF2 and the total focal length of the zoom lens system at the telephoto end is ft, 0.20<fF2 / ft<0.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

15. When the focal length of the lens group LR is fR, and the total focal length of the zoom lens system at the wide-angle end is fw, -1.30<fR / fw<-0.70 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

16. When the focal length of the lens group LR is fR, and the total focal length of the zoom lens system at the telephoto end is ft, -0.50<fR / ft<-0.20 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

17. When the back focus at the wide-angle end of the zoom lens is skw and the focal length of the lens group LR is fR, -0.70<skw / fR<-0.30 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

18. When the focal length of the image-stabilizing lens group IS is fIS and the focal length of the entire zoom lens system at the telephoto end is ft, 0.20<fIS / ft<0.40 The zoom lens according to claim 4, characterized in that it satisfies the following condition.

19. When the amount of movement of the second lens group L2 during zooming from the wide-angle end to the telephoto end is m2, and the focal length of the entire zoom lens system at the wide-angle end is fw, 0.45<m2 / fw<0.85 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

20. When the focal length of the first lens group L1 is f1 and the focal length of the second lens group L2 is f2, -4.50<f1 / f2<-1.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

21. When the focal length of the first lens group L1 is f1, and the focal length of the lens group LFF, which is positioned adjacent to the object side of the first focusing lens group LF1, is fFF, 0.60<f1 / fFF<3.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

22. When the focal length of the first lens group L1 is f1 and the focal length of the first focusing lens group LF1 is fF1, -3.00<f1 / fF1<-1.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

23. When the focal length of the first lens group L1 is f1 and the focal length of the second focusing lens group LF2 is fF2, 2.00<f1 / fF2<3.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

24. When the focal length of the first lens group L1 is f1 and the focal length of the lens group LR is fR, -3.00<f1 / fR<-1.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

25. When the focal length of the first focusing lens group LF1 is fF1 and the focal length of the second focusing lens group LF2 is fF2, -1.60<fF1 / fF2<-0.90 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

26. When the focal length of the second focusing lens group LF2 is fF2 and the focal length of the lens group LR is fR, -1.10<fF2 / fR<-0.50 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

27. The zoom lens according to claim 1, characterized in that the first lens group L1 has a positive lens that satisfies the following condition. 3.00<d1p<3.40 d1p: Specific gravity of the positive lens

28. An imaging device characterized by having a zoom lens according to any one of claims 1 to 27 and a solid-state image sensor that receives an image formed by the zoom lens.

Images