Zoom lens, and imaging apparatus and imaging system having the same

Abstract

To provide a zoom lens that achieves both reduction in size and weight and high optical performance despite a long focal distance and a large aperture ratio.SOLUTION: A zoom lens L0 is composed of a front side group LF, an intermediate group LM, and a rear side group LR, which are arranged in order from an object side to an image side. The front side group is composed of a first front side lens group LF1 having a positive refractive power. The intermediate group is composed of a plurality of lens groups and has a negative composite focal distance at a wide angle end. The rear side group includes a first rear side lens group LR1 having a positive refractive power, a second rear side lens group LR2 having a negative refractive power, a third rear side lens group LR3 having a positive refractive power, and a fourth rear side lens group LR4 having a negative refractive power, which are arranged in order from the object side to the image side. In zooming, the first front side lens group, first rear side lens group, and third rear side lens group are fixed with respect to an image surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a zoom lens and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and the like. [Background technology]

[0002] Zoom lenses used in imaging devices are required to be small and lightweight, effectively correct various aberrations including chromatic aberration, and possess high optical performance. Furthermore, zoom lenses are required to have a long focal length at the telephoto end, a small F-number, and a large aperture ratio. Additionally, zoom lenses are required to have a large zoom ratio and be easy to manufacture.

[0003] Patent Document 1 discloses a zoom lens that achieves a long focal length and a large aperture ratio by positioning the lens group with positive refractive power closest to the object. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-76830 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the zoom lens described in Patent Document 1 tends to have large aberrations, including chromatic aberration, making it difficult to achieve high optical performance. If the power of the lens group constituting the zoom lens is weakened in order to properly correct the aberrations, the zoom lens becomes larger. Furthermore, if aberration correction is performed by increasing the number of lens groups constituting the zoom lens, the mechanical mechanism becomes more complex, resulting in a larger zoom lens.

[0006] This invention provides a zoom lens that achieves both a long focal length and a large aperture ratio while simultaneously being compact, lightweight, and having high optical performance. [Means for solving the problem]

[0007] A zoom lens as one aspect of the present invention comprises a front group, an intermediate group, and a rear group arranged in order from the object side to the image side, the front group comprising a first front lens group with positive refractive power, the intermediate group comprising a plurality of lens groups including at least two or more lens groups and having a negative combined focal length at the wide-angle end, and the rear group comprising a first rear lens group with positive refractive power, a second rear lens group with negative refractive power, a third rear lens group with positive refractive power, and a fourth rear lens group with negative refractive power arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming, and the first front lens group, the first rear lens group, and the third rear lens group are fixed with respect to the image plane during zooming.

[0008] Other objects and features of the present invention are described in the following embodiments. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a zoom lens that achieves both a long focal length and a large aperture ratio while simultaneously being compact, lightweight, and having high optical performance. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of the zoom lens of Example 1. [Figure 2] These are aberration diagrams of the zoom lens of Example 1 at the (A) wide-angle end and (B) telephoto end. [Figure 3] This is a cross-sectional view of the zoom lens of Example 2. [Figure 4] These are aberration diagrams of the zoom lens of Example 2 at the (A) wide-angle end and (B) telephoto end. [Figure 5] This is a cross-sectional view of the zoom lens of Example 3. [Figure 6]It is an aberration diagram of the zoom lens of Example 3 at (A) the wide-angle end and (B) the telephoto end. [Figure 7] It is a cross-sectional view of the zoom lens of Example 4. [Figure 8] It is an aberration diagram of the zoom lens of Example 4 at (A) the wide-angle end and (B) the telephoto end. [Figure 9] It is a cross-sectional view of the zoom lens of Example 5. [Figure 10] It is an aberration diagram of the zoom lens of Example 5 at (A) the wide-angle end and (B) the telephoto end. [Figure 11] It is a schematic diagram of an imaging device.

Modes for Carrying Out the Invention

[0011] Hereinafter, examples of the zoom lens of the present invention and an imaging device having the same will be described based on the accompanying drawings.

[0012] FIG. 1, FIG. 3, FIG. 5, FIG. 7, and FIG. 9 are cross-sectional views of the zoom lens L0 of Examples 1 to 5 at infinity focus, respectively. The zoom lens L0 of each example is used in an imaging device such as a digital video camera, a digital still camera, a broadcast camera, a silver salt film camera, a surveillance camera, etc.

[0013] In each lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The zoom lens L0 of each example is composed of a plurality of lens groups. In the present specification, a lens group is a collection of lenses that move or remain stationary integrally during zooming. That is, in the zoom lens L0 of each example, the interval between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Note that a lens group may be composed of one lens or a plurality of lenses. Also, a lens group may include an aperture stop SP.

[0014] The zoom lens L0 of each example is composed of a front group LF, an intermediate group LM, and a rear group LR, which are arranged in order from the object side to the image side.

[0015] In each lens cross-sectional diagram, LFi represents the i-th lens group from the object side (where i is a natural number) within the front group LF. LMi represents the i-th lens group from the object side (where i is a natural number) within the intermediate group LM. LRi represents the i-th lens group from the object side (where i is a natural number) within the rear group LR.

[0016] Furthermore, SP is the aperture diaphragm, which determines (limits) the light beam at the open F-number (Fno). IP is the image plane, and when the zoom lens L0 of each embodiment is used as the photographic optical system of a digital still camera or digital video camera, the image plane IP is where the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed. When the zoom lens L0 of each embodiment is used as the photographic optical system of a silver halide film camera, the image plane IP is where the photosensitive surface corresponding to the film plane is placed.

[0017] Furthermore, in each lens cross-sectional view, the arrows indicate the movement trajectory of each lens group during zooming from the wide-angle end to the telephoto end. Solid arrows represent the movement of the lens group when zooming from the wide-angle end to the telephoto end when the object distance is infinity, while dashed arrows represent the movement of the lens group when zooming from the wide-angle end to the telephoto end when the object distance is close. The arrows related to focus indicate the direction of movement of the lens group when focusing from infinity to close distance.

[0018] Figures 2, 4, 6, 8, and 10 are aberration diagrams of the zoom lens L0 of Examples 1 to 5 at infinity focus, respectively. In each aberration diagram, (A) is the aberration diagram at the wide-angle end, and (B) is the aberration diagram at the telephoto end. In the spherical aberration diagram, Fno is the F number and indicates the amount of spherical aberration for the d line (wavelength 587.6 nm) and the g line (wavelength 435.8 nm). In the astigmatism diagram, dS indicates the amount of astigmatism at the sagittal image plane, and dM indicates the amount of astigmatism at the meridional image plane. The distortion diagram shows the amount of distortion for the d line. The chromatic aberration diagram shows the amount of chromatic aberration for the g line. ω is the half-angle of view (°) of the image calculated paraxially.

[0019] Next, we will describe the characteristic configuration of the zoom lens L0 in each embodiment.

[0020] To obtain a zoom lens L0 that achieves both a long focal length and large aperture ratio while simultaneously being compact, lightweight, and having high optical performance, it is crucial to appropriately configure the arrangement of the lens groups that make up the zoom lens L0.

[0021] The zoom lens L0 in each embodiment consists of a front group LF, an intermediate group LM, and a rear group LR, arranged in order from the object side to the image side. The zoom lens L0 consists of multiple lens groups, and the spacing between adjacent lens groups changes during zooming.

[0022] In the zoom lens L0 according to each embodiment, the front lens group LF consists of a lens group with positive refractive power (first front lens group) LF1. By positioning the lens group LF1 with positive refractive power closest to the object, it becomes easy to make the zoom lens L0 a so-called telephoto type power configuration, which is advantageous for long focal lengths. Furthermore, the lens group LF1 is fixed to the image plane IP during zooming. Zoom lenses L0 with long focal lengths and large aperture ratios tend to have larger front element diameters, and by fixing the lens group LF1 to the image plane IP, the holding mechanism for the front lens group LF can be simplified, making it easier to miniaturize the zoom lens L0.

[0023] In the zoom lens L0 according to each embodiment, the intermediate group LM consists of multiple lens groups, each containing at least two or more lens groups. The intermediate group LM has a negative combined focal length at the wide-angle end. The intermediate group LM with negative refractive power is the main magnification group, and each lens group moves while changing the distance between adjacent lens groups during zooming. By changing the distance between adjacent lens groups while each lens group moves during zooming, the correction of aberrations during zooming, especially chromatic aberration and astigmatism, is improved.

[0024] In the zoom lens L0 according to each embodiment, the rear lens group LR includes a positive refractive power lens group LR1, a negative refractive power lens group LR2, a positive refractive power lens group LR3, and a negative refractive power lens group LR4, arranged in order from the object side to the image side. Lens group LR1 is called the first rear lens group. Lens group LR2 is called the second rear lens group. Lens group LR3 is called the third rear lens group. Lens group LR4 is called the fourth rear lens group. Lens groups LR1 and LR3 are fixed to the image plane IP during zooming. The rear lens group LR as a whole constitutes a relay group, and by fixing lens groups LR1 and LR3 to the image plane IP, the holding mechanism of the rear lens group LR is simplified, making it easier to miniaturize the zoom lens L0. By moving lens groups LR2 and LR4 during zooming, it is easier to suppress focus shift and aberration fluctuations during zooming. By configuring the positive lens group, which tends to be relatively heavy, as a fixed group, and the negative lens group, which tends to be relatively lighter, as a movable group, it becomes easier to simplify the mechanical mechanism for moving the movable group, thus facilitating the miniaturization of the zoom lens L0. Furthermore, by arranging lens groups LR1 and LR2 in a telephoto power configuration, and lens groups LR3 and LR4 in a telephoto power configuration, it is advantageous to shorten the overall length of the zoom lens L0, thus facilitating the miniaturization of the zoom lens L0.

[0025] Next, we will describe the preferred configurations for the zoom lens L0 according to each embodiment.

[0026] In the zoom lens L0 according to each embodiment, it is preferable that the lens group LR2 moves in a convex trajectory toward the image side when zooming from the wide-angle end to the telephoto end. This makes it easier to correct focus shift during zooming effectively. Here, the convex trajectory toward the image side of lens group A means that, with respect to the amount of movement of lens group A from the wide-angle end when in focus at infinity, the amount of movement toward the image side is taken as a positive value, and the amount of movement takes its maximum value in the intermediate region during zooming.

[0027] In the zoom lens L0 according to each embodiment, it is preferable that the lens group LR4 moves in a convex trajectory toward the image side when zooming from the wide-angle end to the telephoto end. This makes it easier to effectively correct focus shift during zooming.

[0028] In the zoom lens L0 according to each embodiment, it is preferable to move the lens group LR2 towards the image side when focusing from infinity to near distance. By fixing the lens group located on the object side, where the lens diameter tends to be larger, during focusing, and performing focusing with a portion of the subsequent group, where the lens diameter is smaller, it becomes easier to reduce the weight of the focusing lens group. Furthermore, by moving the lens group LR2, which moves during zooming, during focusing as well, the drive mechanism of the lens group LR2 can be shared, simplifying the configuration. This makes it easier to miniaturize the zoom lens L0.

[0029] In the zoom lens L0 according to each embodiment, it is preferable to move the lens group LR4 towards the image side when focusing from infinity to near distance. By fixing the lens group located on the object side, where the lens diameter tends to be larger, during focusing, and performing focusing with a portion of the subsequent group, where the lens diameter is smaller, it becomes easier to reduce the weight of the focusing lens group. Furthermore, by moving the lens group LR4, which moves during zooming, during focusing as well, the drive mechanism of the lens group LR4 can be shared, simplifying the configuration. This makes it easier to miniaturize the zoom lens L0.

[0030] Next, we will describe the conditions that the zoom lens L0 of each embodiment preferably satisfies. The zoom lens L0 of each embodiment preferably satisfies one or more of the following conditional expressions (1) to (18).

[0031] 0.414 <fLF1 / ft<1.434 ···(1) -1.158 < βLMw < -0.285 ... (2) -4.158 < βLMt < -1.200 ···(3) 0.966<βLR4t / βLR4w<1.064 (4) 0.100 <DMRw / fw<1.273 ···(5) 0.177 <DFMt / fLF1<0.466 ···(6) 0.050 <fLR1 / ft<0.461 ···(7) -0.632 <fLR2 / ft<-0.060 ···(8) 0.149 <fLR3 / ft<0.405 ···(9) -1.14 <fLR4 / ft<-0.04 ···(10) 0.100 <skw / fw<0.755 ···(11) 0.639 <Lt / ft<1.764 ···(12) -2.140<(1-βLR2w 2 )βLR2Rw 2 / Fnow<-0.351 ···(13) -1.010<(1-βLR4w 2 )βLR4Rw 2 / Fnow<-0.115 ···(14) 0.290 <DLR1 / fw<0.697 ···(15) 0.028 <TLR2 / fw<0.074 ···(16) 0.014 <DLR3 / fw<0.166 ···(17) 0.001 <TLR4 / fw<0.052 ···(18) Here, fLF1 is the focal length of lens group LF1. ft is the focal length of zoom lens L0 when focused at infinity at the telephoto end. βLMw is the combined lateral magnification of intermediate group LM when focused at infinity at the wide-angle end. βLMt is the combined lateral magnification of intermediate group LM when focused at infinity at the telephoto end. βLR4t is the lateral magnification of lens group LR4 when focused at infinity at the telephoto end. βLR4w is the lateral magnification of lens group LR4 when focused at infinity at the wide-angle end. DMRw is the distance along the optical axis from the image-side lens surface of intermediate group LM to the object-side lens surface of rear group LR at the wide-angle end. fw is the focal length of zoom lens L0 when focused at infinity at the wide-angle end. DFMt is the distance along the optical axis from the image-side lens surface of front group LF to the object-side lens surface of intermediate group LM at the telephoto end. fLR1 is the focal length of lens group LR1. fLR2 is the focal length of lens group LR2. fLR3 is the focal length of lens group LR3. fLR4 is the focal length of lens group LR4. skw is the distance along the optical axis from the image-side lens surface of the rear group LR to the image plane IP at the wide-angle end. Lt is the distance along the optical axis from the object-side lens surface of the front group LF to the image plane IP at the telephoto end. βLR2w is the lateral imaging magnification of lens group LR2 when focused at infinity at the wide-angle end. βLR2Rw is the combined lateral imaging magnification of all lens groups positioned closer to the image than lens group LR2 when focused at infinity at the wide-angle end. Fnow is the F-number of zoom lens L0 when focused at infinity at the wide-angle end. βLR4Rw is the combined lateral imaging magnification of all lens groups positioned closer to the image than lens group LR4 when focused at infinity at the wide-angle end. DLR1 is the distance along the optical axis from the lens surface closest to the object in lens group LR1 to the lens surface closest to the image in lens group LR1. TLR2 is the sum of the thicknesses along the optical axis of all the lenses constituting lens group LR2. DLR3 is the distance along the optical axis from the lens surface closest to the object in lens group LR3 to the lens surface closest to the image in lens group LR3. TLR4 is the sum of the thicknesses along the optical axis of all the lenses constituting lens group LR4.

[0032] Conditional equation (1) defines the relationship between the focal length of lens group LF1 and the focal length of zoom lens L0 at the telephoto end. If the focal length of lens group LF1 exceeds the upper limit of conditional equation (1), it is undesirable because it increases the size of lens group LF1. If the focal length of lens group LF1 falls below the lower limit of conditional equation (1), it is undesirable because it becomes difficult to correct aberrations, especially chromatic aberration at the telephoto end.

[0033] Conditional equation (2) defines the combined lateral magnification of the intermediate group LM at the wide-angle end. Exceeding the upper limit of conditional equation (2) makes it easier to increase the magnification contribution of the intermediate group LM, which is advantageous for increasing the magnification of the zoom lens L0, but it is undesirable because it makes it difficult to correct aberrations, especially astigmatism at the wide-angle end. Exceeding the lower limit of conditional equation (2) is also undesirable because it makes it difficult to increase the magnification of the zoom lens L0.

[0034] Conditional equation (3) defines the combined lateral magnification of the intermediate group LM at the telephoto end. Exceeding the upper limit of conditional equation (3) is undesirable because it makes it difficult to achieve high magnification of the zoom lens L0. Exceeding the lower limit of conditional equation (3) makes it easier to increase the magnification contribution of the intermediate group LM, which is advantageous for achieving high magnification of the zoom lens L0, but it is undesirable because it makes it difficult to correct aberrations, especially spherical aberration at the telephoto end.

[0035] Conditional equation (4) defines the relationship between the horizontal magnification of the image at the wide-angle end and the telephoto end of the lens group LR4. Exceeding the upper limit of conditional equation (4) is advantageous for increasing the magnification of the zoom lens L0, but it is undesirable because it makes it difficult to correct aberrations, especially astigmatism at the telephoto end. Exceeding the lower limit of conditional equation (4) is undesirable because it makes it difficult to increase the magnification of the zoom lens L0.

[0036] Conditional equation (5) defines the ratio of the distance between the intermediate group LM and the rear group LR at the wide-angle end to the focal length of the zoom lens L0 at the wide-angle end. If the distance between the intermediate group LM and the rear group LR at the wide-angle end exceeds the upper limit of conditional equation (5), the zoom lens L0 becomes larger, which is undesirable. If it falls below the lower limit of conditional equation (5), it becomes difficult to achieve high magnification of the zoom lens L0, which is also undesirable. Here, if an aperture plane is located between the lens groups, the distance is calculated excluding the aperture plane.

[0037] Conditional equation (6) defines the relationship between the distance between the front group LF and the intermediate group LM at the telephoto end and the focal length of lens group LF1. If the distance between the front group LF and the intermediate group LM at the telephoto end exceeds the upper limit of conditional equation (6), it is undesirable because the zoom lens L0 becomes larger. If the distance between the front group LF and the intermediate group LM at the telephoto end falls below the lower limit of conditional equation (6), it becomes difficult to reduce the lens diameter of the intermediate group LM, and the zoom lens L0 becomes larger, which is also undesirable. Here, if an aperture plane is located between the lens groups, the distance is calculated excluding the aperture plane.

[0038] Conditional equation (7) defines the relationship between the focal length of lens group LR1 and the focal length of zoom lens L0 at the telephoto end. If the focal length of lens group LR1 exceeds the upper limit of conditional equation (7), it becomes difficult to shorten the overall length of zoom lens L0, and zoom lens L0 becomes larger, which is undesirable. If the focal length of lens group LR1 falls below the lower limit of conditional equation (7), it becomes difficult to correct aberrations, especially axial chromatic aberration and spherical aberration at the telephoto end, which is also undesirable.

[0039] Conditional equation (8) defines the relationship between the focal length of lens group LR2 and the focal length of zoom lens L0 at the telephoto end. If the focal length of lens group LR2 is large, i.e., the absolute value of the focal length of lens group LR2 is small, exceeding the upper limit of conditional equation (8), it becomes difficult to correct aberrations, especially coma aberration at the telephoto end, which is undesirable. If the focal length of lens group LR2 is small, i.e., the absolute value of the focal length of lens group LR2 is large, falling below the lower limit of conditional equation (8), it becomes undesirable because it results in a larger zoom lens L0.

[0040] Conditional equation (9) defines the relationship between the focal length of lens group LR3 and the focal length of zoom lens L0 at the telephoto end. If the focal length of lens group LR3 exceeds the upper limit of conditional equation (9), it becomes difficult to shorten the overall length of zoom lens L0, resulting in a larger zoom lens L0, which is undesirable. If the focal length of lens group LR1 falls below the lower limit of conditional equation (9), it becomes difficult to correct aberrations, especially field curvature at the wide-angle end, which is also undesirable.

[0041] Conditional equation (10) defines the relationship between the focal length of lens group LR4 and the focal length of zoom lens L0 at the telephoto end. If the focal length of lens group LR4 is large, i.e., the absolute value of the focal length of lens group LR4 is small, exceeding the upper limit of conditional equation (10), it becomes difficult to correct aberrations, especially distortion at the telephoto end, which is undesirable. If the focal length of lens group LR4 is small, i.e., the absolute value of the focal length of lens group LR4 is large, falling below the lower limit of conditional equation (10), it is undesirable because it results in a larger zoom lens L0. Conditional equation (11) defines the relationship between the back focus of zoom lens L0 at the wide-angle end and the focal length of zoom lens L0 at the wide-angle end. If the back focus exceeds the upper limit of conditional equation (11), the overall length of zoom lens L0 increases, making zoom lens L0 larger, which is undesirable. If the back focus falls below the lower limit of conditional equation (11), the lens diameter of the lens positioned closest to the image tends to increase, making zoom lens L0 larger, which is also undesirable. Here, if a flat plate or the like is placed on the image side of the lens positioned closest to the image that has refractive power, the back focus is calculated in terms of air equivalent.

[0042] Conditional equation (12) defines the relationship between the overall length of zoom lens L0 at the telephoto end and the focal length of zoom lens L0 at the telephoto end. If the overall length of zoom lens L0 exceeds the upper limit of conditional equation (12), the front element diameter increases, making zoom lens L0 larger, which is undesirable. If the overall length of zoom lens L0 falls below the lower limit of conditional equation (12), it becomes difficult to correct aberrations, especially chromatic aberration and field curvature at the telephoto end, which is also undesirable. Here, if a flat plate or the like is placed on the image side of the lens that has refractive power and is positioned closest to the image, the overall length of the lens is calculated in terms of air pressure.

[0043] Conditional equation (13) defines the relationship between the lateral image magnification of lens group LR2 at the wide-angle end, the combined lateral image magnification of all lens groups positioned closer to the image than lens group LR2, and the F-number of zoom lens L0. If the upper limit of conditional equation (13) is exceeded, the absolute value of the focus sensitivity of lens group LR2 becomes too small, resulting in insufficient focus correction during zooming, or an increase in the amount of movement of lens group LR2 required for focus correction during zooming. This is undesirable because it results in a larger zoom lens L0. If the lower limit of conditional equation (13) is exceeded, the focus sensitivity of lens group LR2 becomes too high, complicating the drive mechanism for lens group LR2 and resulting in a larger zoom lens L0, which is also undesirable. Here, focus sensitivity is the ratio of the amount of movement of the lens group to the amount of movement of the focal plane when the lens group moves along the optical axis.

[0044] Conditional equation (14) defines the relationship between the lateral image magnification of lens group LR4 at the wide-angle end, the combined lateral image magnification of all lens groups positioned closer to the image than lens group LR4, and the F-number of zoom lens L0. If the upper limit of conditional equation (14) is exceeded, the absolute value of the focus sensitivity of lens group LR4 becomes too small, resulting in insufficient focus correction during zooming, or an increase in the amount of movement of lens group LR4 required for focus correction during zooming. This is undesirable because it leads to a larger zoom lens L0. If the lower limit of conditional equation (14) is exceeded, the focus sensitivity of lens group LR4 becomes too high, complicating the drive mechanism for lens group LR4 and leading to a larger zoom lens L0, which is also undesirable.

[0045] Conditional equation (15) defines the relationship between the distance along the optical axis from the lens surface closest to the object in lens group LR1 to the lens surface closest to the image in lens group LR1, and the focal length of the zoom lens L0 at the wide-angle end. Exceeding the upper limit of conditional equation (15) is undesirable because it increases the size of the zoom lens L0. Exceeding the lower limit of conditional equation (15) is undesirable because it makes it difficult to correct aberrations, especially spherical aberration at the telephoto end.

[0046] Conditional equation (16) defines the relationship between the sum of the thicknesses of all lenses constituting the lens group LR2 along the optical axis and the focal length of the zoom lens L0 at the wide-angle end. Exceeding the upper limit of conditional equation (16) is undesirable because it increases the weight of the lens group LR2, complicates the drive mechanism of the lens group LR2, and makes the zoom lens L0 larger. Exceeding the lower limit of conditional equation (16) is undesirable because it makes lens processing difficult and tends to result in unstable shape accuracy, particularly at the telephoto end, which can degrade image quality due to manufacturing errors.

[0047] Conditional equation (17) defines the relationship between the distance along the optical axis from the lens surface closest to the object in lens group LR3 to the lens surface closest to the image in lens group LR3, and the focal length of the zoom lens L0 at the wide-angle end. Exceeding the upper limit of conditional equation (17) is undesirable because it increases the size of the zoom lens L0. Exceeding the lower limit of conditional equation (17) is undesirable because it makes it difficult to correct aberrations, especially coma aberration at the wide-angle end.

[0048] Conditional equation (18) defines the relationship between the sum of the thicknesses of all lenses constituting the lens group LR4 along the optical axis and the focal length of the zoom lens L0 at the wide-angle end. Exceeding the upper limit of conditional equation (18) is undesirable because it increases the weight of the lens group LR4, complicates the drive mechanism of the lens group LR4, and makes the zoom lens L0 larger. Exceeding the lower limit of conditional equation (18) is undesirable because it makes lens processing difficult and tends to result in unstable shape accuracy, particularly at the telephoto end, which can degrade image quality due to manufacturing errors.

[0049] Furthermore, it is more preferable that the numerical ranges of conditional expressions (1) to (18) be within the range of conditional expressions (1a) to (18a) below.

[0050] 0.541 <fLF1 / ft<1.306 ···(1a) -1.049<βLMw<-0.394 (2a) -3.741<βLMt<-1.300 (3a) 0.978<βLR4t / βLR4w<1.052 (4a) 0.219 <DMRw / fw<1.122 ···(5a) 0.214 <DFMt / fLF1<0.430 ···(6a) 0.081 <fLR1 / ft<0.407 ···(7a) -0.55 <fLR2 / ft<-0.08 ···(8a) 0.181 <fLR3 / ft<0.373 ···(9a) -0.978 <fLR4 / ft<-0.060 ···(10a) 0.12 <skw / fw<0.66 ···(11a) 0.780 <Lt / ft<1.624 ···(12a) -1.916<(1-βLR2w 2 )βLR2Rw 2 / Fnow<-0.574 ···(13a) -0.898<(1-βLR4w 2 )βLR4Rw 2 / Fnow<-0.227 ···(14a) 0.341 <DLR1 / fw<0.647 ···(15a) 0.034 <TLR2 / fw<0.068 ···(16a) 0.033 <DLR3 / fw<0.147 ···(17a) 0.006 <TLR4 / fw<0.045 ···(18a) Furthermore, it is even more preferable that the numerical ranges of conditional expressions (1) to (18) be the same as the numerical ranges of conditional expressions (1b) to (18b).

[0051] 0.605 <fLF1 / ft<1.242 ···(1b) -0.995<βLMw<-0.449 (2b) -3.532<βLMt<-1.449 (3b) 0.984<βLR4t / βLR4w<1.046 (4b) 0.294 <DMRw / fw<1.047 ···(5b) 0.232 <DFMt / fLF1<0.412 ···(6b) 0.108 <fLR1 / ft<0.380 ···(7b) -0.508 <fLR2 / ft<-0.100 ···(8b) 0.197 <fLR3 / ft<0.357 ···(9b) -0.896 <fLR4 / ft<-0.082 ···(10b) 0.143 <skw / fw<0.613 ···(11b) 0.850 <Lt / ft<1.553 ···(12b) - 1.805 < (1 - βLR2w 2 )βLR2Rw 2 / Fnow < -0.686 ···(13b) -0.842 < (1 - βLR4w 2 )βLR4Rw 2 2 / Fnow < -0.283 ···(14b) 0.366 < DLR1 / fw < 0.621 ···(15b) 0.037 < TLR2 / fw < 0.065 ···(16b) 0.042 < DLR3 / fw < 0.137 ···(17b) 0.010 < TLR4 / fw < 0.042 ···(18b) Next, the zoom lens L0 of each embodiment will be described in detail.

[0052] The zoom lens L0 of Embodiment 1 is composed of a front group LF, an intermediate group LM, and a rear group LR arranged in order from the object side to the image side. The front group LF consists of a lens group LF1 with a positive refractive power. The lens group LF1 is fixed with respect to the image plane IP during zooming. The intermediate group LM consists of a lens group LM1 with a negative refractive power, a lens group LM2 with a negative refractive power, and a lens group LM3 with a positive refractive power, arranged in order from the object side to the image side. The lens groups LM1, LM2, and LM3 move along different trajectories while changing the distance between each other during zooming. The rear group LR consists of a lens group LR1 with a positive refractive power, a lens group LR2 with a negative refractive power, a lens group LR3 with a positive refractive power, a lens group LR4 with a negative refractive power, and a lens group LR5 with a negative refractive power, arranged in order from the object side to the image side. The lens group LR5 is called the fifth rear lens group. The lens groups LR1, LR3, and LR5 are fixed with respect to the image plane IP during zooming. The lens groups LR2 and LR4 move during zooming, and the distance between adjacent lens groups changes. The lens group LR1 includes the aperture stop SP. When focusing from infinity to a short distance, the lens group LR2 moves toward the image side, and the lens group LR4 moves toward the image side.

[0053] The zoom lens L0 of Example 2 consists of a front group LF, an intermediate group LM, and a rear group LR, arranged in order from the object side to the image side. The front group LF consists of a lens group LF1 with positive refractive power. Lens group LF1 is fixed to the image plane IP during zooming. The intermediate group LM consists of a lens group LM1 with negative refractive power, a lens group LM2 with negative refractive power, and a lens group LM3 with positive refractive power, arranged in order from the object side to the image side. Lens groups LM1, LM2, and LM3 each move along different trajectories while changing the distance between them during zooming. The rear group LR consists of a lens group LR1 with positive refractive power, a lens group LR2 with negative refractive power, a lens group LR3 with positive refractive power, a lens group LR4 with negative refractive power, and a lens group LR5 with positive refractive power, arranged in order from the object side to the image side. Lens groups LR1, LR3, and LR5 are fixed relative to the image plane IP during zooming. Lens groups LR2 and LR4 move during zooming, changing the spacing between adjacent lens groups. Lens group LR1 includes the aperture diaphragm SP. When focusing from infinity to near distance, lens group LR2 moves towards the image, and lens group LR4 also moves towards the image.

[0054] The zoom lens L0 of Example 3 consists of a front group LF, an intermediate group LM, and a rear group LR, arranged in order from the object side to the image side. The front group LF consists of a lens group LF1 with positive refractive power. Lens group LF1 is fixed to the image plane IP during zooming. The intermediate group LM consists of a lens group LM1 with negative refractive power and a lens group LM2 with positive refractive power, arranged in order from the object side to the image side. Lens groups LM1 and LM2 move along different trajectories, changing their distance from each other during zooming. The rear group LR consists of a lens group LR1 with positive refractive power, a lens group LR2 with negative refractive power, a lens group LR3 with positive refractive power, and a lens group LR4 with negative refractive power, arranged in order from the object side to the image side. Lens groups LR1 and LR3 are fixed to the image plane IP during zooming. Lens groups LR2 and LR4 move during zooming, changing the spacing between adjacent lens groups. Lens group LR1 includes the aperture diaphragm SP. When focusing from infinity to close distance, lens group LR2 moves towards the image, and lens group LR4 also moves towards the image.

[0055] The zoom lens L0 of Example 4 consists of a front group LF, an intermediate group LM, and a rear group LR, arranged in order from the object side to the image side. The front group LF consists of a lens group LF1 with positive refractive power. Lens group LF1 is fixed to the image plane IP during zooming. The intermediate group LM consists of a lens group LM1 with positive refractive power, a lens group LM2 with negative refractive power, and a lens group LM3 with negative refractive power, arranged in order from the object side to the image side. Lens groups LM1, LM2, and LM3 each move along different trajectories while changing the distance between them during zooming. The rear group LR consists of a lens group LR1 with positive refractive power, a lens group LR2 with negative refractive power, a lens group LR3 with positive refractive power, a lens group LR4 with negative refractive power, and a lens group LR5 with positive refractive power, arranged in order from the object side to the image side. Lens groups LR1, LR3, and LR5 are fixed relative to the image plane IP during zooming. Lens groups LR2 and LR4 move during zooming, changing the spacing between adjacent lens groups. Lens group LR1 includes the aperture diaphragm SP. When focusing from infinity to near distance, lens group LR2 moves towards the image, and lens group LR4 also moves towards the image.

[0056] The zoom lens L0 of Example 5 consists of a front group LF, an intermediate group LM, and a rear group LR, arranged in order from the object side to the image side. The front group LF consists of a lens group LF1 with positive refractive power. Lens group LF1 is fixed to the image plane IP during zooming. The intermediate group LM consists of a lens group LM1 with negative refractive power and a lens group LM2 with negative refractive power, arranged in order from the object side to the image side. Lens groups LM1 and LM2 move along different trajectories, changing their distance from each other during zooming. The rear group LR consists of a lens group LR1 with positive refractive power, a lens group LR2 with negative refractive power, a lens group LR3 with positive refractive power, a lens group LR4 with negative refractive power, and a lens group LR5 with positive refractive power, arranged in order from the object side to the image side. Lens groups LR1, LR3, and LR5 are fixed to the image plane IP during zooming. Lens groups LR2 and LR4 move during zooming, changing the spacing between adjacent lens groups. Lens group LR1 includes the aperture diaphragm SP. When focusing from infinity to close distance, lens group LR2 moves towards the image, and lens group LR4 also moves towards the image.

[0057] In the zoom lenses L0 of Examples 1 to 5, all optical surfaces that possess power are refractive surfaces. This makes it possible to easily obtain optical performance equivalent to or better than that obtained when the optical surfaces are composed of diffractive or reflective surfaces, with a lower manufacturing difficulty.

[0058] In the zoom lens L0 of Examples 1 to 5, image shake correction may be reduced by moving a portion of the zoom lens L0 in a direction that includes a component perpendicular to the optical axis. In particular, by making the portion moved during image shake correction a lens group located on the image side with a relatively small diameter, the actuator for driving can be made smaller, and the lens device including the zoom lens L0 can be miniaturized.

[0059] The numerical values ​​corresponding to Examples 1 to 5 are shown below.

[0060] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incidence side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of the optical element with respect to the d-line. Note that the Abbe number νd of a certain material with respect to the d-line is given by Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC. νd = (Nd-1) / (NF-NC) It is represented as follows.

[0061] In each numerical example, d, focal length (mm), F-number, and half-angle of view (°) are all values ​​when the zoom lens L0 of each example is in focus on an object at infinity. "Back focus BF" is the distance along the optical axis from the final lens surface (the lens surface closest to the image) of the zoom lens L0 to the paraxial image plane, expressed in terms of air equivalent length. "Total lens length" is the length obtained by adding the back focus to the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) of the zoom lens L0 to the final lens surface. "Lens group" includes not only cases where it is composed of multiple lenses, but also cases where it is composed of a single lens.

[0062] Furthermore, if the optical surface is aspherical, the sign * is added to the right of the surface number. The aspherical shape is defined as follows, where X is the displacement from the surface vertex in the optical axis direction, h is the height from the optical axis perpendicular to the optical axis, R is the paraaxial radius of curvature, k is the cone constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of their respective orders. 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 This is expressed as follows. Note that "e±XX" in each aspherical coefficient is "×10± XXIt means "...".

[0063] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd 1 165.007 2.00 1.77047 29.7 2 102.210 9.19 1.43875 94.7 3 -2836.692 0.17 4 92.024 7.79 1.49700 81.5 5 419.169 (variable) 6 119.719 5.24 1.69895 30.1 7 -9119.138 0.13 8 222.608 1.40 1.59522 67.7 9 43.169 (variable) 10 -102.107 1.40 1.59522 67.7 11 127.029 (variable) 12 70.978 4.61 1.95375 32.3 13 551.675 2.99 14 -100.875 1.60 1.83481 42.7 15 411.903 (variable) 16* 44.710 11.44 1.43875 94.7 17* -71.025 8.85 18 (aperture) ∞ 3.75 19 -99.516 1.40 1.65412 39.7 20 51.804 2.68 21 66.454 1.20 1.85478 24.8 22 38.396 7.49 1.76450 49.1 23* -209.796 0.48 24 57.306 5.70 1.49700 81.5 25 -149.817 (variable) 26 5546.126 3.24 1.92286 20.9 27 -80.703 1.30 1.63980 34.5 28 34.856 (Variable) 29* 77.507 9.26 1.76450 49.1 30* -71.565 (variable) 31 -170.418 1.30 1.61800 63.4 32 130.262 (variable) 33 -54.506 2.00 1.56883 56.4 34 -900.480 (variable) Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-1.40533e-06 A 6=-1.37186e-10 A 8=-2.50564e-13 Page 17 K = 0.00000e+00 A 4= 1.84457e-06 A 6=-5.84368e-10 A 8= 1.81459e-13 Page 23 K = 0.00000e+00 A 4= 7.76781e-07 A 6= 4.20243e-10 A 8=-4.52171e-13 Page 29 K = 0.00000e+00 A 4= 1.06625e-06 A 6= 2.14195e-10 A 8=-4.48782e-13 Page 30 K = 0.00000e+00 A 4= 1.30655e-06 A 6=-3.60951e-10 A 8=-4.14141e-13 A10 = 2.69960e-16 Various data Zoom ratio 2.03 Wide-angle, Medium, Telephoto Focal length 72.10 102.58 146.49 F number 2.05 2.05 2.05 Half-angle (°): 16.70, 11.91, 8.40 Image height 21.64 21.64 21.64 Lens length 217.31 217.31 217.31 BF 13.71 13.71 13.71 d 5 0.99 24.11 44.60 d 9 10.45 11.69 12.84 d11 13.53 5.80 1.61 d15 35.03 18.40 0.94 d25 2.04 2.31 0.83 d28 24.27 24.00 25.48 d30 5.98 5.46 0.99 d32 14.71 15.24 19.71 d34 13.71 13.71 13.71 Zoom lens group data Group starting plane focal length 1 1 172.74 2 6 -204.55 3 10 -94.89 4 12 463.78 5 16 51.74 6 26 -68.38 7 29 50.02 8 31 -119.27 9 33 -102.08 [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 115.694 1.60 1.72047 34.7 2 74.988 10.27 1.43875 94.7 3 -1590.880 0.16 4 71.857 7.74 1.43387 95.1 5 229.206 (variable) 6 389.572 3.67 1.61340 44.3 7 -224.087 0.12 8 90.573 1.40 1.59522 67.7 9 33.897 (Variable) 10 -60.561 1.40 1.59410 60.5 11 203.142 (variable) 12 59.142 3.77 1.85478 24.8 13 453.435 3.11 14 -58.814 1.60 1.62041 60.3 15 148.393 (variable) 16* 40.715 8.14 1.49700 81.5 17* -75.250 4.67 18 (aperture) ∞ 1.97 19 382.638 1.40 1.77047 29.7 20 42.520 2.86 21 60.178 1.20 1.85478 24.8 22 33.812 6.57 1.76450 49.1 23* -213.080 0.48 24 43.774 4.96 1.53775 74.7 25 -350.467 (variable) 26 205.352 2.84 1.92286 20.9 27 -108.404 1.30 1.75700 47.8 28 29.208 (variable) 29* 5250.944 5.21 1.76450 49.1 30* -44.832 (variable) 31 -54.992 1.30 1.64769 33.8 32 66.879 (Variable) 33 59.424 2.95 2.00100 29.1 34 114.407 (variable) Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-2.31070e-06 A 6=-6.94530e-10 A 8=-2.38664e-13 Page 17 K = 0.00000e+00 A 4= 2.02846e-06 A 6=-1.46198e-09 A 8= 9.00137e-13 Page 23 K = 0.00000e+00 A 4= 7.16919e-07 A 6= 6.86451e-10 A 8=-1.34064e-12 Page 29 K = 0.00000e+00 A 4= 2.50842e-06 A 6= 4.78254e-11 A 8= 6.47138e-13 Page 30 K = 0.00000e+00 A 4= 2.28696e-06 A 6=-1.15709e-09 A 8= 1.22768e-12 A10 = -4.49859e-16 Various data Zoom ratio 2.69 Wide-angle, Medium, Telephoto Focal length 72.12 118.22 194.03 F-number 2.90 2.90 2.90 Half-angle (°): 16.70, 10.37, 6.36 Image height 21.64 21.64 21.64 Lens length 217.47 217.47 217.47 BF 37.98 37.98 37.98 d 5 5.06 28.70 48.86 d 9 9.25 11.39 12.84 d11 15.00 4.47 0.89 d15 34.16 18.92 0.88 d25 2.04 2.81 2.04 d28 21.94 21.16 21.93 d30 2.83 4.40 2.30 d32 8.52 6.95 9.05 d34 37.98 37.98 37.98 Zoom lens group data Group starting plane focal length 1 1 145.02 2 6 -154.47 3 10 -78.37 4 12 -922.61 5 16 37.30 6 26 -50.98 7 29 58.17 8 31 -46.40 9 33 120.30 [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 134.111 1.60 1.72047 34.7 2 80.218 10.14 1.43875 94.7 3 -775.327 0.18 4 75.023 8.68 1.43875 94.7 5 532.216 (variable) 6 445.813 3.44 1.69895 30.1 7 -294.830 0.14 8 175.033 1.40 1.59522 67.7 9 38.588 11.66 10 -57.616 1.40 1.49700 81.5 11 177.597 (variable) 12 57.526 3.30 2.00069 25.5 13 196.444 3.20 14 -65.414 1.60 1.57099 50.8 15 182.032 (variable) 16* 43.266 6.86 1.49700 81.5 17* -103.574 1.92 18 (aperture) ∞ 1.93 19 412.522 1.40 1.77047 29.7 20 43.078 3.08 21 49.136 1.20 1.77047 29.7 22 31.252 7.46 1.61881 63.9 23* -135.299 0.47 24* 78.279 3.95 1.61881 63.9 25* -237.452 (variable) 26 -1018.157 2.90 1.92286 20.9 27 -62.570 1.30 1.72342 38.0 28 34.675 (Variable) 29 81.801 8.05 1.72916 54.7 30 -54.353 (variable) 31 -54.656 1.47 1.62230 53.2 32 114.890 (Variable) Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4=-4.04995e-06 A 6=-3.31752e-10 A 8=-3.57838e-12 Page 17 K = 0.00000e+00 A 4=-2.08588e-06 A 6= 3.00429e-09 A 8=-4.27630e-12 Page 23 K = 0.00000e+00 A 4= 1.29005e-06 A 6= 7.58678e-10 A 8=-1.43134e-12 Page 24 K = 0.00000e+00 A 4=-5.91443e-06 A 6=-8.87417e-11 A 8= 9.37729e-12 Page 25 K = 0.00000e+00 A 4=-6.13202e-06 A 6= 2.47877e-10 A 8= 6.96779e-12 A10 = -1.05276e-15 Various data Zoom ratio 2.69 Wide-angle, Medium, Telephoto Focal length 72.11 117.88 194.01 F-number 2.90 2.90 2.90 Half-angle (°): 16.70, 10.40, 6.36 Image height 21.64 21.64 21.64 Lens length 217.42 217.42 217.42 BF 40.87 40.95 44.89 d 5 1.81 26.40 48.14 d11 21.73 7.45 1.12 d15 26.69 16.38 0.98 d25 5.29 5.31 1.30 d28 25.52 25.50 29.51 d30 6.77 6.68 2.74 d32 40.87 40.95 44.89 Zoom lens group data Group starting plane focal length 1 1 135.06 2 6 -49.11 3 12 709.83 4 16 42.74 5 26 -53.85 6 29 45.93 7 31 -59.32 [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 352.733 6.02 1.48749 70.2 2 ∞ 0.20 3 161.012 10.18 1.43387 95.1 4 -24395.615 20.51 5 124.191 12.26 1.43875 94.7 6 -416.630 2.00 1.61340 44.3 7 135.078 (variable) 8 777.435 4.28 1.62004 36.3 9 -228.593 (variable) 10 134.114 1.80 1.59410 60.5 11 49.127 8.10 12 -115.558 1.80 1.59410 60.5 13 468.402 (variable) 14 90.032 2.94 1.85478 24.8 15 228.662 4.89 16 -67.711 1.60 1.59522 67.7 17 -309.202 (variable) 18* 43.441 10.01 1.49700 81.5 19* -150.947 9.14 20 (aperture) ∞ 6.75 21 723.463 1.40 1.80610 40.9 22 41.374 3.22 23 61.014 1.20 1.85478 24.8 24 36.303 7.42 1.76450 49.1 25* -195.224 0.48 26 35.968 6.42 1.43875 94.7 27 -480.116 (variable) 28 144.255 2.62 1.94594 18.0 29 -268.421 1.30 1.90043 37.4 30 32.274 (variable) 31* 1374.090 5.12 1.85400 40.4 32* -55.133 (variable) 33 -65.563 1.30 1.59522 67.7 34 49.807 (Variable) 35 59.292 6.15 2.00100 29.1 36 -463.861 1.20 1.94594 18.0 37 112.541 (variable) Image plane ∞ Aspherical data Side 18 K = 0.00000e+00 A 4=-8.16007e-07 A 6=-4.16757e-10 A 8=-1.29761e-13 Page 19 K = 0.00000e+00 A 4= 1.05337e-06 A 6=-5.99226e-10 A 8= 2.73848e-13 Page 25 K = 0.00000e+00 A 4= 6.05418e-07 A 6= 3.58203e-10 A 8=-5.59395e-13 Page 31 K = 0.00000e+00 A 4= 1.76915e-06 A 6=-2.56191e-10 A 8=-4.45134e-13 Page 32 K = 0.00000e+00 A 4= 1.17015e-06 A 6=-6.72420e-10 A 8=-5.95424e-13 A10 = 1.63998e-16 Various data Zoom ratio 2.97 Wide-angle, Medium, Telephoto Focal length 98.00 168.99 291.00 F-number 2.90 2.90 2.90 Half-angle (°): 12.45, 7.30, 4.25 Image height 21.64 21.64 21.64 Lens length 317.42 317.42 317.42 BF 38.00 38.00 38.00 d 7 5.76 46.62 79.10 d 9 0.98 8.11 16.76 d13 8.79 1.68 1.14 d17 82.43 41.55 0.96 d27 2.04 2.80 0.89 d30 26.48 25.71 27.62 d32 5.23 5.67 2.39 d34 7.39 6.95 10.24 d37 38.00 38.00 38.00 Zoom lens group data Group starting plane focal length 1 1 316.23 2 8 285.37 3 10 -69.48 4 14 -1334.01 5 18 49.29 6 28 -48.08 7 31 62.17 8 33 -47.35 9 35 109.72 [Numerical Example 5] Unit: mm Surface data Face number rd nd νd 1 248.051 7.06 1.49700 81.5 2 ∞ 0.20 3 170.105 8.84 1.43387 95.1 4 14541.336 8.10 5 135.007 10.08 1.43875 94.7 6 -1332.063 2.00 1.61340 44.3 7 148.757 (variable) 8 410.912 3.03 1.61340 44.3 9 -1104.902 1.00 10 100.412 1.80 1.59410 60.5 11 44.919 8.72 12 -159.344 1.80 1.59410 60.5 13 185.938 (variable) 14 75.783 3.08 1.85478 24.8 15 184.071 9.68 16 -85.628 1.60 1.59522 67.7 17 402.876 (variable) 18* 47.056 8.00 1.43875 94.7 19* -179.498 20.28 20 (aperture) ∞ 2.02 21 285.759 1.40 1.80610 40.9 22 48.976 2.45 23 58.468 1.20 1.85478 24.8 24 36.182 7.58 1.69350 53.2 25* -144.615 0.48 26 39.588 5.36 1.43875 94.7 27 1212.238 (variable) 28 422.839 2.11 1.94594 18.0 29 -174.640 2.00 30 -175.439 2.00 1.77250 49.6 31 34.442 (variable) 32 -91.520 2.00 1.67270 32.1 33 -675.283 5.15 34* 94.292 4.67 1.69350 53.2 35* -75.502 (variable) 36 -165.767 2.00 1.59522 67.7 37 41.150 2.00 38 43.492 2.00 1.61340 44.3 39 58.293 (Variable) 40 95.195 4.86 1.77047 29.7 41 -219.350 1.20 1.94594 18.0 42 1063.768 (variable) Image plane ∞ Aspherical data Side 18 K = 0.00000e+00 A 4=-7.06274e-07 A 6=-4.14704e-10 A 8= 1.77035e-13 Page 19 K = 0.00000e+00 A 4= 7.46097e-07 A 6=-4.07505e-10 A 8= 3.51179e-13 Page 25 K = 0.00000e+00 A 4= 6.81748e-07 A 6= 9.43138e-11 A 8=-2.02463e-13 Page 34 K = 0.00000e+00 A 4= 1.88299e-06 A 6=-1.59021e-09 A 8= 3.33089e-12 Page 35 K = 0.00000e+00 A 4= 1.13805e-06 A 6=-1.57268e-09 A 8= 4.46558e-12 A10 = -2.58389e-15 Various data Zoom ratio 3.82 Wide-angle, Medium, Telephoto Focal length 101.97 199.46 389.88 F-number 4.10 4.10 4.10 Half-angle (°): 11.98, 6.19, 3.18 Image height 21.64 21.64 21.64 Lens length 359.04 359.04 359.04 BF 52.64 52.64 52.64 d 7 3.96 58.99 102.97 d13 8.50 4.12 7.62 d17 99.13 48.48 0.99 d27 2.04 2.99 1.82 d31 14.41 13.46 14.63 d35 2.10 7.63 3.81 d39 30.55 25.02 28.84 d42 52.64 52.64 52.64 Zoom lens group data Group starting plane focal length 1 1 260.97 2 8 -81.45 3 14 -1000.36 4 18 52.87 5 28 -53.67 6 32 92.19 7 36 -69.26 8 40 155.14 The various values ​​in each numerical example are summarized in Table 1 below.

[0064] [Table 1]

[0065] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens L0 of the present invention as an imaging optical system will be described with reference to Figure 11. Figure 11 is a diagram showing the configuration of the imaging device 10. In Figure 11, the imaging device 10 comprises a camera body 13, a lens device 11 including one of the zoom lenses L0 described in Embodiments 1 to 5, and an image sensor (photodetector) 12 that receives the optical image formed by the zoom lens L0 and converts it into photoelectric energy. The image sensor 12 is built into the camera body 13. As the image sensor 12, a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or a CMOS sensor can be used. The lens device 11 and the camera body 13 may be configured as an integral unit or may be configured to be detachable. The camera body 13 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0066] In this way, by applying the zoom lens L0 of each embodiment to an imaging device such as a digital still camera, an imaging device 10 that is compact, lightweight, and has high optical performance can be obtained.

[0067] Furthermore, the imaging device 10 of this embodiment is not limited to the digital still camera shown in Figure 11, but can be applied to various imaging devices such as broadcast cameras, silver halide film cameras, and surveillance cameras.

[0068] [Imaging System] Furthermore, an imaging system (surveillance camera system) may be configured that includes the zoom lens L0 of each embodiment and a control unit that controls the zoom lens L0. In this case, the control unit can control the zoom lens so that each lens group moves as described above during zooming, focusing, and image shake correction. At this time, the control unit does not need to be integrally configured with the zoom lens L0, and the control unit may be configured separately from the zoom lens L0. For example, a configuration may be adopted in which a control unit (control device) located far away from the drive unit that drives each lens of the zoom lens L0 has a transmission unit that sends control signals (commands) to control the zoom lens L0. With such a control unit, the zoom lens L0 can be remotely operated.

[0069] Alternatively, the control unit may be equipped with an operating section such as a controller or buttons for remotely controlling the zoom lens L0, thereby enabling a configuration that controls the zoom lens in response to user input to the operating section. For example, the operating section may include a zoom-in button and a zoom-out button. The control unit can then be configured to send a signal to the drive unit of the zoom lens L0 so that when the user presses the zoom-in button, the magnification of the zoom lens increases, and when the user presses the zoom-out button, the magnification of the zoom lens decreases.

[0070] Furthermore, the imaging system may have a display unit, such as an LCD panel, that displays information (movement status) related to the zoom of the zoom lens L0. This information could include, for example, the zoom magnification (zoom status) or the amount of movement of each lens group (movement status). In this case, the user can remotely operate the zoom lens L0 via the control unit while viewing the zoom information of the zoom lens L0 displayed on the display unit. In this case, the display unit and the control unit may be integrated by, for example, using a touch panel.

[0071] Each of the above embodiments includes the following configurations. (Composition 1) It consists of a front group, an intermediate group, and a rear group, arranged in order from the object side to the image side. The aforementioned front group consists of a first front lens group with positive refractive power, The aforementioned intermediate group consists of multiple lens groups, including at least two lens groups, and has a negative combined focal length at the wide-angle end. The aforementioned rear lens group includes, arranged in order from the object side to the image side, a first rear lens group with positive refractive power, a second rear lens group with negative refractive power, a third rear lens group with positive refractive power, and a fourth rear lens group with negative refractive power. When zooming, the spacing between adjacent lens groups changes. A zoom lens characterized in that, during zooming, the first front lens group, the first rear lens group, and the third rear lens group are fixed with respect to the image plane. (Configuration 2) When the focal length of the first front lens group is fLF1 and the focal length of the zoom lens at infinity focus at the telephoto end is ft, 0.414 <fLF1 / ft<1.434 A zoom lens according to configuration 1, characterized in that it satisfies the following condition. (Composition 3) When the combined image lateral magnification of the intermediate group at the wide-angle end when focused at infinity is βLMw, -1.158 < βLMw < -0.285 A zoom lens according to configuration 1 or 2, characterized by satisfying the following conditional expression. (Composition 4) When the combined image lateral magnification of the intermediate group at the telephoto end when infinity focus is achieved is βLMt, -4.158 < βLMt < -1.200 A zoom lens according to any one of configurations 1 to 3, characterized by satisfying the following conditional expression. (Composition 5) When the lateral image magnification of the fourth rear lens group at infinity focus at the telephoto end is βLR4t, and the lateral image magnification of the fourth rear lens group at infinity focus at the wide-angle end is βLR4w, 0.966 < βLR4t / βLR4w < 1.064 A zoom lens according to any one of configurations 1 to 4, characterized by satisfying the following conditional expression. (Composition 6) When DMRw is the distance along the optical axis from the image-side lens surface of the intermediate group to the object-side lens surface of the rear group at the wide-angle end, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.100 <DMRw / fw<1.273 A zoom lens according to any one of configurations 1 to 5, characterized by satisfying the following conditional expression. (Composition 7) When DFMt is the distance along the optical axis from the image-side lens surface of the front lens group to the object-side lens surface of the intermediate lens group at the telephoto end, and fLF1 is the focal length of the first front lens group, 0.177 <DFMt / fLF1<0.466 A zoom lens according to any one of configurations 1 to 6, characterized by satisfying the following conditional expression. (Composition 8) When the focal length of the first rear lens group is fLR1 and the focal length of the zoom lens at infinity focus at the telephoto end is ft, 0.050 <fLR1 / ft<0.461 A zoom lens according to any one of configurations 1 to 7, characterized by satisfying the following conditional expression. (Composition 9) When the focal length of the second rear lens group is fLR2 and the focal length of the zoom lens at infinity focus at the telephoto end is ft, -0.632 <fLR2 / ft<-0.060 A zoom lens according to any one of configurations 1 to 8, characterized by satisfying the following conditional expression. (Composition 10) When the focal length of the third rear lens group is fLR3 and the focal length of the zoom lens at infinity focus at the telephoto end is ft, 0.149 <fLR3 / ft<0.405 A zoom lens according to any one of configurations 1 to 9, characterized by satisfying the following conditional expression. (Composition 11) When the focal length of the fourth rear lens group is fLR4 and the focal length of the zoom lens at infinity focus at the telephoto end is ft, -1.14 <fLR4 / ft<-0.04 A zoom lens according to any one of configurations 1 to 10, characterized by satisfying the following conditional expression. (Composition 12) When skw is the distance along the optical axis from the image-side lens surface of the rear group to the image plane at the wide-angle end, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.100 <skw / fw<0.755 A zoom lens according to any one of configurations 1 to 11, characterized by satisfying the following conditional expression. (Composition 13) When Lt is the distance along the optical axis from the lens surface closest to the object in the front group to the image plane at the telephoto end, and ft is the focal length of the zoom lens when infinity focus is achieved at the telephoto end, 0.639 <Lt / ft<1.764 A zoom lens according to any one of configurations 1 to 12, characterized by satisfying the following conditional expression. (Composition 14) When the image lateral magnification of the second rear lens group at infinity focus at the wide-angle end is βLR2w, the combined image lateral magnification of all lens groups positioned closer to the image than the second rear lens group at infinity focus at the wide-angle end is βLR2Rw, and the F-number of the zoom lens at infinity focus at the wide-angle end is Fnow, -2.140<(1-βLR2w 2 )βLR2Rw 2 / Fnow<-0.351 A zoom lens according to any one of configurations 1 to 13, characterized by satisfying the following conditional expression. (Composition 15) When the horizontal imaging magnification of the fourth rear lens group at infinity focus at the wide-angle end is βLR4w, the combined horizontal imaging magnification of all lens groups positioned closer to the image than the fourth rear lens group at infinity focus at the wide-angle end is βLR4Rw, and the F-number of the zoom lens at infinity focus at the wide-angle end is Fnow, -1.010<(1-βLR4w 2 )βLR4Rw 2 / Fnow<-0.115 A zoom lens according to any one of configurations 1 to 14, characterized by satisfying the following conditional expression. (Composition 16) When DLR1 is the distance along the optical axis from the lens surface closest to the object in the first rear lens group to the lens surface closest to the image in the first rear lens group, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.290 <DLR1 / fw<0.697 A zoom lens according to any one of configurations 1 to 15, characterized by satisfying the following conditional expression. (Composition 17) When TLR2 is the sum of the thicknesses of all lenses constituting the second rear lens group along the optical axis, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.028 <TLR2 / fw<0.074 A zoom lens according to any one of configurations 1 to 16, characterized by satisfying the following conditional expression. (Composition 18) When DLR3 is the distance along the optical axis from the lens surface closest to the object in the third rear lens group to the lens surface closest to the image in the third rear lens group, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.014 <DLR3 / fw<0.166 A zoom lens according to any one of configurations 1 to 17, characterized by satisfying the following conditional expression. (Composition 19) When TLR4 is the sum of the thicknesses of all lenses constituting the fourth rear lens group along the optical axis, and fw is the focal length of the zoom lens when in focus at infinity at the wide-angle end, 0.001 <TLR4 / fw<0.052 A zoom lens according to any one of configurations 1 to 18, characterized by satisfying the following conditional expression. (Composition 20) When zooming from the wide-angle end to the telephoto end, the zoom lens according to any one of Configurations 1 to 19, wherein the second rear-side lens group moves along a locus convex toward the image side when focused at infinity. (Configuration 21) When zooming from the wide-angle end to the telephoto end, the zoom lens according to any one of Configurations 1 to 20, wherein the fourth rear-side lens group moves along a locus convex toward the image side when focused at infinity. (Configuration 22) When focusing from infinity to a short distance, the zoom lens according to any one of Configurations 1 to 21, wherein the second rear-side lens group moves toward the image side. (Configuration 23) When focusing from infinity to a short distance, the zoom lens according to any one of Configurations 1 to 22, wherein the fourth rear-side lens group moves toward the image side. (Configuration 24) The rear-side lens group includes, in order from the object side to the image side, the first rear-side lens group, the second rear-side lens group, the third rear-side lens group, the fourth rear-side lens group, and a fifth rear-side lens group having a positive refractive power, and is the zoom lens according to any one of Configurations 1 to 23. (Configuration 25) The rear-side lens group includes, in order from the object side to the image side, the first rear-side lens group, the second rear-side lens group, the third rear-side lens group, the fourth rear-side lens group, and a fifth rear-side lens group having a negative refractive power, and is the zoom lens according to any one of Configurations 1 to 23. (Configuration 26) The rear-side lens group includes, in order from the object side to the image side, the first rear-side lens group, the second rear-side lens group, the third rear-side lens group, and the fourth rear-side lens group, and is the zoom lens according to any one of Configurations 1 to 23; (Configuration 27) A zoom lens according to any one of Configurations 1 to 26, and An imaging device having an imaging element that receives an image formed by the zoom lens. (Configuration 28) An imaging system comprising a zoom lens according to any one of Configurations 1 to 26, and a control unit for controlling the zoom lens during zooming. (Configuration 29) The imaging system according to Configuration 28, wherein the control unit is configured separately from the zoom lens and has a transmission unit for transmitting a control signal for controlling the zoom lens. (Configuration 30) The imaging system according to Configuration 28 or 29, wherein the control unit is configured separately from the zoom lens and has an operation unit for operating the zoom lens. (Configuration 31) The imaging system according to any one of Configurations 28 to 30, further comprising a display unit for displaying information related to zooming of the zoom lens.

[0072] As described above, the preferred embodiments and examples of the present invention have been explained. However, the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes are possible within the scope of the gist thereof.

Explanation of Reference Numerals

[0073] Front group LF Intermediate group LM Rear group LR First front lens group LF1 First rear lens group LR1 Second rear lens group LR2 Third rear lens group LR3 Fourth rear lens group LR4

Claims

1. Comprising a front group, an intermediate group, and a rear group, arranged in order from the object side to the image side, The front group consists of a first front lens group with a positive refractive power, The intermediate group consists of a plurality of lens groups including at least two or more lens groups, and has a negative combined focal length at the wide-angle end, The rear group includes a first rear lens group with a positive refractive power, a second rear lens group with a negative refractive power, a third rear lens group with a positive refractive power, and a fourth rear lens group with a negative refractive power, arranged in order from the object side to the image side, During zooming, the distance between adjacent lens groups changes, During zooming, the first front lens group, the first rear lens group, and the third rear lens group are fixed with respect to the image plane, A zoom lens, characterized in that the second rear lens group moves toward the image side during focusing from infinity to a short distance.

2. When the focal length of the first front lens group is fLF1 and the focal length of the zoom lens at the telephoto end is ft, 0.414 < fLF1 / ft < 1.434 The zoom lens according to claim 1, characterized in that the conditional expression is satisfied.

3. When the combined imaging lateral magnification of the intermediate group at the wide-angle end is βLMW, -1.158 < βLMW < -0.285 The zoom lens according to claim 1, characterized in that the conditional expression is satisfied.

4. When the combined imaging lateral magnification of the intermediate group at the telephoto end is βLMt, -4.158 < βLMt < -1.200 The zoom lens according to claim 1, characterized in that the conditional expression is satisfied.

5. When the imaging lateral magnification of the fourth rear lens group at the telephoto end is βLR4t and the imaging lateral magnification of the fourth rear lens group at the wide-angle end is βLR4w, 0.966 < βLR4t / βLR4w < 1.064 The zoom lens according to claim 1, characterized in that the conditional expression is satisfied.

6. When the distance on the optical axis from the most image-side lens surface of the intermediate group to the most object-side lens surface of the rear group at the wide-angle end is DMRw and the focal length of the zoom lens at the wide-angle end is fw, 0.100 < DMRw / fw < 1.273 The zoom lens according to claim 1, characterized in that the conditional expression is satisfied.

7. When the distance on the optical axis from the most image-side lens surface of the front group to the most object-side lens surface of the intermediate group at the telephoto end is DFMt and the focal length of the first front lens group is fLF1, 0.177 < DFMt / fLF1 < 0.466 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

8. When the focal length of the first rear lens group is fLR1 and the focal length of the zoom lens at the telephoto end is ft, 0.050 < fLR1 / ft < 0.461 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

9. When the focal length of the second rear lens group is fLR2 and the focal length of the zoom lens at the telephoto end is ft, -0.632 < fLR2 / ft < -0.060 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

10. When the focal length of the third rear lens group is fLR3 and the focal length of the zoom lens at the telephoto end is ft, 0.149 < fLR3 / ft < 0.405 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

11. When the focal length of the fourth rear lens group is fLR4 and the focal length of the zoom lens at the telephoto end is ft, -1.14 < fLR4 / ft < -0.04 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

12. When the distance on the optical axis from the most image-side lens surface of the rear group at the wide-angle end to the image plane is skw and the focal length of the zoom lens at the wide-angle end is fw, 0.100 < skw / fw < 0.755 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

13. When the distance on the optical axis from the most object-side lens surface of the front group at the telephoto end to the image plane is Lt and the focal length of the zoom lens at the telephoto end is ft, 0.639 < Lt / ft < 1.764 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

14. When the lateral magnification of imaging of the second rear lens group at the wide-angle end is βLR2w, the combined lateral magnification of imaging of all lens groups arranged on the image side of the second rear lens group at the wide-angle end is βLR2Rw, and the F number of the zoom lens at the wide-angle end is Fnow, -2.140 < (1 - βLR2w ２ )βLR2Rw ２ / Fnow < -0.351 The zoom lens according to claim 1, characterized in that it satisfies the conditional expression:

15. When the lateral magnification of image formation of the fourth rear lens group at the wide-angle end is βLR4w, the combined lateral magnification of image formation of all lens groups arranged on the image side of the fourth rear lens group at the wide-angle end is βLR4Rw, and the F-number of the zoom lens at the wide-angle end is Fnow, -1.010 < (1 - βLR4w ２ )βLR4Rw ２ / Fnow < -0.115 The zoom lens according to claim 1, characterized in that the following conditional expression is satisfied.

16. When the distance on the optical axis from the most object-side lens surface of the first rear lens group to the most image-side lens surface of the first rear lens group is DLR1, and the focal length of the zoom lens at the wide-angle end is fw, 0.290 < DLR1 / fw < 0.697 The zoom lens according to claim 1, characterized in that the following conditional expression is satisfied.

17. When the total thickness on the optical axis of all lenses constituting the second rear lens group is TLR2, and the focal length of the zoom lens at the wide-angle end is fw, 0.028 < TLR2 / fw < 0.074 The zoom lens according to claim 1, characterized in that the following conditional expression is satisfied.

18. When the distance on the optical axis from the most object-side lens surface of the third rear lens group to the most image-side lens surface of the third rear lens group is DLR3, and the focal length of the zoom lens at the wide-angle end is fw, 0.014 < DLR3 / fw < 0.166 The zoom lens according to claim 1, characterized in that the following conditional expression is satisfied.

19. When the total thickness on the optical axis of all lenses constituting the fourth rear lens group is TLR4, and the focal length of the zoom lens at the wide-angle end is fw, 0.001 < TLR4 / fw < 0.052 The zoom lens according to claim 1, characterized in that the following conditional expression is satisfied.

20. When zooming from the wide-angle end to the telephoto end, the second rear lens group moves along a locus convex toward the image side. The zoom lens according to claim 1, characterized in that.

21. When zooming from the wide-angle end to the telephoto end, the fourth rear lens group moves along a locus convex toward the image side. The zoom lens according to claim 1, characterized in that.

22. When focusing from infinity to a short distance, the fourth rear lens group moves toward the image side. The zoom lens according to claim 1, characterized in that.

23. The zoom lens according to claim 1, wherein the rear group is composed of the first rear lens group, the second rear lens group, the third rear lens group, the fourth rear lens group, and the fifth rear lens group having a positive refractive power, which are arranged in order from the object side to the image side.

24. The zoom lens according to claim 1, wherein the rear group is composed of the first rear lens group, the second rear lens group, the third rear lens group, the fourth rear lens group, and the fifth rear lens group having a negative refractive power, which are arranged in order from the object side to the image side.

25. The zoom lens according to claim 1, wherein the rear group is composed of the first rear lens group, the second rear lens group, the third rear lens group, and the fourth rear lens group, which are arranged in order from the object side to the image side.

26. A zoom lens according to any one of claims 1 to 25, An imaging device, comprising an imaging element that receives an image formed by the zoom lens.

27. An imaging system, comprising a zoom lens according to any one of claims 1 to 25, and a control unit that controls the zoom lens during zooming.

28. The imaging system according to claim 27, wherein the control unit is configured separately from the zoom lens and has a transmission unit that transmits a control signal for controlling the zoom lens.

29. The imaging system according to claim 27, wherein the control unit is configured separately from the zoom lens and has an operation unit for operating the zoom lens.

30. The imaging system according to claim 27, further comprising a display unit that displays information regarding zooming of the zoom lens.

Images