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

Abstract

To provide a zoom lens that achieves a short back and suppresses variation in optical performance by focusing in a wide angle area at a wide angle of view.SOLUTION: A zoom lens consists of a first lens group having positive refractive power, a second lens group having negative refractive power, and a subsequent group including a plurality of lens groups, which are arranged in order from an object side to an image side. The distance between adjacent lens groups is changed during zooming in the zoom lens. The subsequent group includes a focus lens group that moves during focusing, and the focus lens group includes a positive and negative lens. An air interval between the positive lens and the negative lens, a distance of the focus lens group on an optical axis when focusing at infinity from a lens surface closest to the object side to a lens surface closest to the image side, a focal distance of the focus lens group, focal distances of the zoom lens at a wide angle end and a telephoto end, and a focal distance of the lens group arranged adjacent to the object side of the focus lens group are set respectively and appropriately.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] There is a demand for a compact and lightweight zoom lens that is compatible with so-called mirrorless cameras that do not have a quick-return mirror. For example, a known zoom lens includes, arranged in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group including multiple lens groups, with the second lens group serving as the main variable magnification group (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-109233 Summary of the Invention [Problem to be solved by the invention]

[0004] The zoom lens of Patent Document 1 achieves high magnification and high image quality, but the angle of view on the wide-angle side is not necessarily sufficient.

[0005] In recent years, in order to achieve compactness, imaging devices have been proposed that electrically correct distortion, primarily in the wide-angle range, among various aberrations of zoom lenses. However, in such imaging devices, fluctuations in aberrations, particularly fluctuations in field curvature, become significant during focusing.

[0006] An object of the present invention is to provide a zoom lens that is compatible with a short back focal length, has a wide angle of view, and suppresses fluctuations in optical performance due to focusing in the wide-angle region, as well as an imaging device and an imaging system that have the same. [Means for solving the problem]

[0007] A zoom lens according to one aspect of the present invention includes, arranged in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, Focus that moves when focusing A zoom lens system is configured with a subsequent group including a lens group, and the spacing between adjacent lens groups changes during zooming, and the subsequent group is The lens comprises, arranged in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a positive refractive power; The focus lens group includes a positive lens and a negative lens, and the air gap between the positive lens and the negative lens is Lfpn, the distance on the optical axis from the lens surface of the focus lens group closest to the object to the lens surface of the focus lens group closest to the image when focusing at infinity is Tf, the focal length of the focus lens group is ff, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the zoom lens at the telephoto end is ft, and the focal length of the lens group arranged adjacent to the focus lens group on the object side is fo. , the focal length of the sixth lens group is fp When 0.50 <Lfpn / Tf<0.75 -1.5 <ff / √(fw×ft)<-0.7 -1.0 <ff / fo<-0.5 -1.0 <ff / fp<-0.5 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a zoom lens that is compatible with a short back focal length, has a wide angle of view, and suppresses fluctuations in optical performance due to focusing in the wide-angle range, as well as an imaging device and an imaging system that have the same. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a zoom lens at a wide-angle end according to a first embodiment. [Figure 2] 4A, 4B, and 4C are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, the middle end, and the telephoto end. [Figure 3] FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end according to a second embodiment. [Figure 4]10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, the middle end, and the telephoto end. [Figure 5] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end according to a third embodiment. [Figure 6] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the middle end, and the telephoto end. [Figure 7] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end according to a fourth embodiment. [Figure 8] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the middle end, and the telephoto end. [Figure 9] FIG. 10 is a cross-sectional view of a zoom lens at the wide-angle end according to a fifth embodiment. [Figure 10] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the middle end, and the telephoto end. [Figure 11] FIG. 13 is a cross-sectional view of a zoom lens at the wide-angle end according to a sixth embodiment. [Figure 12] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 6 at the wide-angle end, the middle end, and the telephoto end. [Figure 13] FIG. 13 is a lens cross-sectional view of a zoom lens according to a seventh embodiment at the wide-angle end. [Figure 14] 10A, 10B, and 10C are aberration diagrams of the zoom lens of Example 7 at the wide-angle end, the middle end, and the telephoto end. [Figure 15] FIG. 1 is a schematic diagram of an imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0011] 1, 3, 5, 7, 9, 11, and 13 are cross-sectional views of the zoom lenses at the wide-angle end of Examples 1 to 7. The zoom lenses of the respective Examples are used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras.

[0012] In each lens cross-sectional view, the left side is the object side and the right side is the image side. The zoom lens of each embodiment is configured with multiple lens groups. In this specification, a lens group refers to a group of lenses that move or remain stationary as a unit during zooming. That is, in the zoom lens of each embodiment, the distance between adjacent lens groups changes during zooming. Note that a lens group may be configured with a single lens, or may be configured with multiple lenses. The lens group may also include an aperture stop.

[0013] The zoom lens of each embodiment comprises, arranged in order from the object side to the image side, a first lens unit L1 with positive refractive power, a second lens unit L2 with negative refractive power, and a subsequent unit including a plurality of lens units.

[0014] SP is an aperture stop, which is located on the object side of the third lens unit L3 included in the subsequent lens group and moves integrally with the third lens unit L3 during zooming. IP is an image plane, and when the zoom lens of each embodiment is used as the photographic optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is located thereon. When the zoom lens of each embodiment is used as the photographic optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is located at the image plane IP. GB is a glass block, which corresponds to a low-pass filter or IR cut filter.

[0015] In the zoom lens of each embodiment, each lens group moves in the direction of the solid arrow when zooming from the wide-angle end to the telephoto end. The wide-angle end and the telephoto end are zoom positions when the lens group that moves during zooming is located at both ends of the range of movement along the optical axis, due to the mechanism.

[0016] Figures 2(A), 4(A), 6(A), 8(A), 10(A), 12(A), and 14(A) are aberration diagrams at the wide-angle ends of the zoom lenses of Examples 1 to 7, respectively. Figures 2(B), 4(B), 6(B), 8(B), 10(B), 12(B), and 14(B) are aberration diagrams at the intermediate ends of the zoom lenses of Examples 1 to 7, respectively. Figures 2(C), 4(C), 6(C), 8(C), 10(C), 12(C), and 14(C) are aberration diagrams at the telephoto ends of the zoom lenses of Examples 1 to 7, respectively.

[0017] In the spherical aberration diagram, Fno is the F-number, and shows the amount of spherical aberration for the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔS shows the amount of astigmatism on the sagittal image plane, and ΔM shows the amount of astigmatism on the meridional image plane. In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration for the g-line is shown. ω is the half angle of view (degrees).

[0018] Next, the characteristic configuration of the zoom lens of each embodiment will be described.

[0019] According to aberration theory, the process of focusing from infinity to a close distance can be separated into the process in which the object distance moves from infinity to a close distance (object distance movement) and the process in which the focus lens group moves to focus at that object distance (focus lens group movement). According to aberration theory, the change in field curvature increases in principle as the object distance moves, and the change in field curvature during focusing also tends to increase. This is proven by the fact that because the third-order aberration coefficient V related to distortion is large, the amount of change in the third-order aberration coefficient III related to astigmatism, expressed by the following equation, also increases as the object distance moves (see Non-Patent Document 1 (Yoshiya Matsui, "Lens Design Method," Chapter 4)). JPEG0007739076000001.jpg11119

[0020] where δ is the object distance movement parameter, II S is the third-order aberration coefficient related to pupil coma, I Sis the third-order aberration coefficient related to the spherical aberration of the pupil.

[0021] Zoom lenses that use inner focusing facilitate the miniaturization and weight reduction of the focus lens group, facilitating quick focusing. Generally, as image sensors become larger, zoom lenses are required to have high optical performance throughout the entire zoom range and all object distances. For example, there is a demand for minimal aberration fluctuations during focusing, and in particular, minimal fluctuations in field curvature to maintain high optical performance across the entire image field.

[0022] On the other hand, zoom lenses used in imaging devices with the function of electrically correcting various aberrations allow for distortion, making it easy to reduce the overall system size while achieving a wide angle of view. However, such zoom lenses experience increased fluctuations in field curvature when focusing in the wide-angle range. Furthermore, as image sensors become larger, fluctuations in field curvature during focusing tend to increase. In order for a zoom lens to have a predetermined photographic angle of view, minimize fluctuations in aberrations during focusing, and achieve high optical performance across the entire image field, it is necessary to appropriately set the zoom type, lens configuration, etc. Furthermore, it is necessary to appropriately set the off-axis chief ray incident on the focus lens group.

[0023] In the zoom lens of each embodiment, the angle of incidence α of the off-axis chief ray in the focus lens group at the wide-angle end is ~ and height h ~ By increasing the value of JPEG0007739076000002.jpg899

[0024] is increased. This makes it possible to correct for fluctuations in field curvature that occur when the object distance at the wide-angle end changes by moving the focus lens group. Note that f is the focal length of the focus lens group, and Δh is the amount of fluctuation in the incidence height of the on-axis marginal ray of light on the focus lens group due to movement of the focus lens group. In order to correct for fluctuations in field curvature, it is important to appropriately set the focal length of the focus lens group.

[0025] In the zoom lens of each embodiment, the subsequent lens group includes a focus lens group that moves during focusing, and the focus lens group includes a positive lens and a negative lens, and the air gap between the positive lens and the negative lens is widened. As a result, the ray height h of the axial ray and the ray height h of the off-axial chief ray in the focus lens group are ~ This increases the change in the curvature of field on the wide-angle side and the spherical aberration on the telephoto side, thereby suppressing the change in the curvature of field on the wide-angle side and the spherical aberration on the telephoto side.

[0026] The zoom lens of each embodiment satisfies the following conditional expressions (1) to (3).

[0027] 0.50 <Lfpn / Tf<0.75 (1) -1.5 <ff / √(fw×ft)<-0.7 (2) -1.0 <ff / fo<-0.5 (3) Here, LFpn is the air gap between the positive lens and the negative lens included in the focus lens group. Tf is the distance on the optical axis from the lens surface of the focus lens group closest to the object to the lens surface of the focus lens group closest to the image when focusing at infinity. ff is the focal length of the focus lens group. fw is the focal length of the zoom lens at the wide-angle end. ft is the focal length of the zoom lens at the telephoto end. fo is the focal length of the lens group arranged adjacent to the focus lens group on the object side.

[0028] Conditional expression (1) is a conditional expression concerning the air spacing between the positive and negative lenses in the focus lens group, and is a conditional expression concerning, in particular, the fluctuation in spherical aberration during focusing and the overall length of the zoom lens. If the lower limit of conditional expression (1) is not met, the spacing between the lenses in the focus lens group becomes narrower, and the change in the height of the axial ray becomes smaller, making it difficult to suppress the fluctuation in spherical aberration during focusing. If the upper limit of conditional expression (1) is exceeded, the spacing between the lenses in the focus lens group becomes wider, which is advantageous for suppressing the fluctuation in spherical aberration during focusing, but it is undesirable because it increases the overall length of the zoom lens.

[0029] Conditional expression (2) is a conditional expression concerning the power arrangement of the focus lens group, and is a conditional expression concerning fluctuations in field curvature during focusing at the wide-angle end in particular. If the lower limit of conditional expression (2) is not met, the power of the focus lens group weakens and the angle of incidence of off-axial chief rays becomes small, making it difficult to suppress fluctuations in field curvature during focusing. If the upper limit of conditional expression (2) is exceeded, the power of the focus lens group becomes strong, which is advantageous in suppressing fluctuations in field curvature during focusing, but it is undesirable because it increases the change in the exit pupil when changing magnification.

[0030] Conditional expression (3) is a conditional expression concerning the power arrangement of the lens group arranged adjacent to the focus lens group on the object side, and is a conditional expression concerning fluctuations in field curvature during focusing at the wide-angle end in particular. If the lower limit of conditional expression (3) is not met, the power of the lens group arranged adjacent to the focus lens group on the object side becomes stronger, and the angle of incidence of off-axial chief rays becomes smaller, making it difficult to suppress fluctuations in field curvature during focusing. If the upper limit of conditional expression (3) is met, the power of the lens group arranged adjacent to the focus lens group on the object side becomes weaker, which is advantageous in suppressing fluctuations in field curvature during focusing, but it becomes difficult to correct spherical aberration and axial chromatic aberration throughout the entire zoom range.

[0031] With the above-described configuration, it is possible to realize a zoom lens that is compatible with a short back focal length, has a wide angle of view, and suppresses fluctuations in optical performance due to focusing in the wide-angle region.

[0032] It is preferable that the numerical ranges of the conditional expressions (1) to (3) be set to the numerical ranges of the following conditional expressions (1a) to (3a).

[0033] 0.50 <Lfpn / Tf<0.73 (1a) -1.40 <ff / √(fw×ft)<-0.75 (2a) -0.98 <ff / fo<-0.55 (3a) It is more preferable that the numerical ranges of the conditional expressions (1) to (3) be the numerical ranges of the following conditional expressions (1b) to (3b).

[0034] 0.52 <Lfpn / Tf<0.70 (1b) -1.3 <ff / √(fw×ft)<-0.8 (2b) -0.95 <ff / fo<-0.60 (3b) Next, the configurations that are preferably satisfied in the zoom lens of each embodiment will be described.

[0035] It is preferable that the positive lens element in the focus lens group, at least one of whose surfaces is aspherical, has a shape in which the positive power weakens at the periphery, thereby making it possible to suppress fluctuations in field curvature during zooming and focusing.

[0036] It is preferable that at least a portion of the lens group arranged adjacent to the image side of the second lens group L2 in the subsequent group moves in a direction that includes a component perpendicular to the optical axis of the zoom lens when correcting the image plane movement of the subject image, thereby correcting blur in the captured image caused by vibration of the zoom lens.

[0037] Next, conditions that the zoom lens of each embodiment should preferably satisfy will be described. The zoom lens of each embodiment should preferably satisfy one or more of the following conditional expressions (4) to (7).

[0038] -0.6<(Rfobj+Rfimg) / (Rfobj-Rfimg)<0.2 (4) -1.0 <ff / fp<-0.5 (5) 0<|νfn-νfp|<15 (6) 1.50 <ndfav<1.75 (7) Here, Rfobj is the curvature of the lens surface closest to the object in the focus lens group. radius Rfimg is the curvature of the lens surface closest to the image side in the focus lens group. radius where fp is the focal length of the positive lens group located closest to the image in the subsequent lens group. νfn is the Abbe number of the positive lens. νfp is the Abbe number of the negative lens. ndfav is the average refractive index of the lenses included in the focus lens group.

[0039] Conditional expression (4) is a conditional expression concerning the shape of the focus lens group, and in particular, a conditional expression concerning fluctuations in field curvature during focusing on the wide-angle side. If the lower limit of conditional expression (4) is not met, the biconcave shape of the focus lens group weakens and the angle of incidence of off-axial chief rays decreases, making it difficult to suppress fluctuations in field curvature during focusing. If the upper limit of conditional expression (4) is met, the biconcave shape of the focus lens group weakens and the angle of incidence of off-axial chief rays increases, which is advantageous for suppressing fluctuations in field curvature during focusing, but makes it difficult to correct spherical aberration.

[0040] Conditional expression (5) is a conditional expression concerning the power distribution of the positive lens group located closest to the image in the subsequent lens group, and is a conditional expression concerning color shading associated with light rays incident on the exit pupil and the sensor. If the lower limit of conditional expression (5) is not satisfied, the power of the positive lens group located closest to the image in the subsequent lens group becomes stronger, which is undesirable because it causes large fluctuations in the exit pupil when zooming from the wide-angle end to the telephoto end. If the upper limit of conditional expression (5) is satisfied, the power of the positive lens group located closest to the image in the subsequent lens group becomes weaker, which causes large amounts of light rays incident on the sensor, which is undesirable because it makes the lens more susceptible to the effects of color shading.

[0041] Conditional expression (6) is a conditional expression relating to the glass materials of the lenses included in the focus lens group, and in particular to the correction of lateral chromatic aberration. If the lower limit of conditional expression (6) is not met, the difference in Abbe numbers becomes small, making it difficult to suppress fluctuations in axial chromatic aberration during focusing. If the upper limit of conditional expression (6) is met, the difference in Abbe numbers becomes large, making it difficult to suppress fluctuations in lateral chromatic aberration during focusing.

[0042] Conditional expression (7) is a conditional expression relating to the glass material of the lenses included in the focus lens group, and is a conditional expression relating in particular to curvature of field and focusing speed. If the average refractive index of the lenses included in the focus lens group decreases below the lower limit of conditional expression (7), it becomes difficult to correct curvature of field. If the average refractive index of the lenses included in the focus lens group increases above the upper limit of conditional expression (7), the weight of the lenses increases, which is undesirable because it slows down the focusing speed.

[0043] It is preferable that the numerical ranges of the conditional expressions (4) to (7) be set to the numerical ranges of the following conditional expressions (4a) to (7a).

[0044] -0.58<(Rfobj+Rfimg) / (Rfobj-Rfimg)<0.20 (4a) -0.98 <ff / fp<-0.55 (5a) 3<|νfn-νfp|<15 (6a) 1.53 <ndfav<1.73 (7a) It is more preferable that the numerical ranges of the conditional expressions (4) to (7) be the numerical ranges of the following conditional expressions (4b) to (7b).

[0045] -0.55<(Rfobj+Rfimg) / (Rfobj-Rfimg)<0.18 (4b) -0.95 <ff / fp<-0.60 (5b) 5<|νfn-νfp|<15 (6b) 1.55 <ndfav<1.70 (7b) In the zoom lens of each embodiment, distortion, one of the various aberrations, may be corrected by electrical image processing. In particular, by making the effective image circle diameter at the wide-angle end smaller than that at the telephoto end and correcting distortion, this contributes to a reduction in the diameter of the front lens element.

[0046] Next, the zoom lens of each embodiment will be described in detail.

[0047] The zoom lens of each embodiment is made up of a first lens unit L1 to a sixth lens unit L6, arranged in order from the object side to the image side, and having positive, negative, positive, positive, negative, and positive refractive powers.

[0048] The first lens group L1 consists of a cemented lens consisting of a negative meniscus lens with a convex object-side surface cemented together with a positive meniscus lens with a convex object-side surface, and a positive meniscus lens with a convex object-side surface. To achieve compactness, the refractive power of the first lens group L1 is strengthened within an appropriate range. Strengthening the refractive power of the first lens group L1 increases the occurrence of various aberrations within the first lens group L1, particularly spherical aberration and axial chromatic aberration at the telephoto end. Therefore, by dividing the positive refractive power of the first lens group L1 between two positive lenses, spherical aberration can be suppressed. Furthermore, chromatic aberration can be effectively corrected by using anomalous dispersion glass for at least one positive lens.

[0049] The second lens group L2 consists of a negative meniscus lens with a convex lens surface facing the object, a negative lens with concave lens surfaces on both sides, and a positive lens with a convex lens surface facing the object. To increase the zoom ratio, the refractive power of the second lens group L2 is strengthened within an appropriate range. Increasing the refractive power of the second lens group L2 increases the amount of aberrations, particularly distortion and curvature of field. Therefore, by sharing the negative refractive power of the second lens group L2 between two negative lenses, the amount of field aberration can be reduced. Furthermore, the shape of the lenses in the second lens group L2 is optimized for curvature of field so that distortion can be corrected by electronic image processing. Furthermore, using high-dispersion glass for the positive lens suppresses lateral chromatic aberration at the wide-angle end. This configuration enables the overall length of the zoom lens to be shortened while increasing the zoom ratio.

[0050] The third lens group L3 consists of a positive lens with convex lens surfaces on both sides and a negative meniscus lens with a convex lens surface facing the object. To increase the zoom ratio, the refractive power of the third lens group L3 is strengthened within an appropriate range. Strengthening the refractive power of the third lens group L3 increases aberrations, particularly spherical aberration and coma at the wide-angle end. Therefore, by using an aspherical lens as the positive lens closest to the object, spherical aberration can be effectively corrected. Furthermore, by placing a concave meniscus lens on the image side of the aspherical lens, coma can be effectively corrected.

[0051] The fourth lens group L4 is composed of a positive lens with a convex lens surface facing the image side, and a cemented lens formed by cementing together a negative meniscus lens with a concave lens surface facing the object side and a positive lens with a convex lens surface facing the image side. To increase the zoom ratio, the refractive power of the fourth lens group L4 is strengthened within an appropriate range. Strengthening the refractive power of the fourth lens group L4 increases the amount of aberrations that occur in the fourth lens group L4, particularly axial chromatic aberration and coma aberration. Therefore, by distributing the positive refractive power of the fourth lens group L4 among multiple convex lenses, the occurrence of coma aberration can be suppressed. Furthermore, the use of a cemented lens can suppress the occurrence of axial chromatic aberration.

[0052] The fifth lens unit L5 consists of a positive meniscus lens with a convex lens surface facing the image side and a negative lens with concave lens surfaces on both sides. By arranging the two lenses with a large air gap between them, spherical aberration and field curvature can be effectively corrected by taking advantage of the difference in height of light rays passing through the lenses.

[0053] The sixth lens group L6 is composed of a positive meniscus lens with a convex lens surface facing the image side. By using a small number of lenses, the sixth lens group L6 is made thinner and lighter. Furthermore, by making the lens surface facing the image side convex, it is possible to correct field curvature and reduce the angle of light rays incident on the image sensor, while also correcting chromatic aberration of magnification throughout the entire zoom range.

[0054] In the zoom lenses of Examples 1 and 2, when zooming from the wide-angle end to the telephoto end, the first lens group L1 and the second lens group L2 move toward the image side, and the third lens group L3, the fourth lens group L4, and the sixth lens group L6 move toward the object side to change magnification. Furthermore, the fifth lens group L5 moves toward the object side to correct image plane fluctuations that accompany changing magnification. The first lens group L1 moves along a convex locus toward the image side.

[0055] In the zoom lenses of Examples 3 to 7, when zooming from the wide-angle end to the telephoto end, the first lens group L1 and the second lens group L2 move toward the image side, and the third lens group L3 and the fourth lens group L4 move toward the object side to change magnification. Furthermore, the fifth lens group L5 moves toward the object side to correct image plane fluctuations that accompany changing magnification. The first lens group L1 moves along a convex locus toward the image side.

[0056] The zoom lens of each embodiment employs an inner focusing system in which focusing is performed by moving the fifth lens unit L5 along the optical axis. The solid curve 5a and dotted curve 5b for the fifth lens unit L5 represent the movement locus for correcting image plane fluctuations that occur with magnification changes when focusing on an object at infinity and a close distance, respectively. By moving the fifth lens unit L5 toward the object side in this way, the space between the fourth lens unit L4 and the sixth lens unit L6 can be effectively utilized, thereby shortening the overall length of the zoom lens.

[0057] At the telephoto end, focusing from an object at infinity to a close object is performed by retracting the fifth lens unit L5 backward along the arrow 5c. The first lens unit L1 is stationary during focusing, but may be moved as necessary for aberration correction.

[0058] Numerical Examples 1 to 7 corresponding to Examples 1 to 7, respectively, are shown below.

[0059] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element. Note that the Abbe number vd of a certain material is given by the following equation, where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines: νd=(Nd-1) / (NF-NC) It is expressed as:

[0060] In each numerical example, d, focal length (mm), F-number, and half angle of view (degrees) are all values ​​when the zoom lens of each example is focused on an object at infinity. "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. "Lens group" is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens.

[0061] If the optical surface is aspherical, an asterisk (*) is added to the right of the surface number. The aspherical shape is expressed as follows: X is the displacement from the vertex of the surface in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, A10, and A12 are the aspherical coefficients of each order. X=(h 2 / R) / [1+{1-(1+K)(h / R) 2} 1 / 2 +A4×h 4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 In addition, "e±XX" in each aspherical coefficient is "×10± XX " means.

[0062] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd vd 1 134.550 1.80 1.85478 24.8 2 62.953 5.02 1.59282 68.6 3 776.481 0.51 4 39.552 4.77 1.69680 55.5 5 110.603 (variable) 6 223.304 1.10 1.88300 40.8 7 14.246 6.90 8 -57.459 0.90 1.59282 68.6 9 35.847 0.58 10 25.143 2.94 1.92286 20.9 11 90.877 (variable) 12 (Aperture) ∞ 1.00 13* 15.687 4.20 1.58313 59.4 14* -79.843 0.12 15 14.954 1.00 1.76182 26.5 16 11.119 5.26 17 ∞ (variable) 18 -145.564 2.58 1.85150 40.8 19 -19.832 1.17 20 -12.074 0.80 1.72825 28.5 21 -254.898 4.20 1.59282 68.6 22 -13.704 (variable) 23* -52.279 2.56 1.53110 55.9 24* -25.829 5.44 25 -26.288 0.95 1.76385 48.5 26 56.459 (variable) 27 3041.338 5.32 1.74400 44.8 28 -29.857 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K=-4.39390e-001 A 4=-3.04886e-006 A 6=-1.29596e-007 Side 14 K = 0.00000e+000 A 4= 2.41835e-005 A 6=-2.20215e-007 Page 23 K = 0.00000e+000 A 4= 2.86695e-005 A 6= 5.53983e-007 Page 24 K = 0.00000e+000 A 4= 5.23781e-005 A 6= 4.72578e-007 A 8= 9.33407e-010 Various data Zoom ratio 4.40 Wide-angle Mid-range Telephoto Focal length 15.45 18.61 68.00 F-number 4.12 4.12 4.12 Half angle of view (degrees) 36.92 33.71 11.36 Lens total length 106.58 104.86 125.20 BF 10.68 11.17 12.16 d 5 1.43 3.31 30.10 d11 28.24 22.30 2.01 d17 1.50 1.10 1.50 d22 1.94 2.87 6.30 d26 3.68 5.00 14.03 d28 6.75 7.24 8.23 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 77.18 12.10 2 6 -17.53 12.42 3 12 31.76 11.58 4 18 41.28 8.74 5 23 -33.12 8.95 6 27 39.77 5.32 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 128.738 1.80 1.84666 23.9 2 66.961 4.62 1.59282 68.6 3 491.249 0.51 4 39.739 4.78 1.67790 55.3 5 108.458 (variable) 6 205.298 1.10 1.90043 37.4 7 14.389 6.90 8 -55.249 0.90 1.59282 68.6 9 33.417 0.49 10 25.005 3.49 1.92286 20.9 11 117.369 (variable) 12 (Aperture) ∞ 1.00 13* 15.739 4.25 1.58313 59.4 14* -81.051 0.12 15 14.812 1.00 1.74000 28.3 16 11.039 5.26 17 ∞ (variable) 18 -176.449 2.59 1.85150 40.8 19 -20.038 1.17 20 -12.095 0.80 1.74077 27.8 21 -8496.543 4.41 1.59282 68.6 22 -13.615 (variable) 23* -54.079 2.54 1.53110 55.9 24* -26.237 5.69 25 -25.498 0.95 1.76385 48.5 26 61.877 (variable) 27 -664.070 5.09 1.74950 35.3 28 -29.117 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K=-4.39390e-001 A 4=-1.82961e-006 A 6=-1.33210e-007 Side 14 K = 0.00000e+000 A 4= 2.46890e-005 A 6=-2.20510e-007 Page 23 K = 0.00000e+000 A 4= 4.04472e-005 A 6= 6.32429e-007 Page 24 K = 0.00000e+000 A 4= 6.42979e-005 A 6= 5.39016e-007 A 8= 1.29733e-009 Various data Zoom ratio 4.40 Wide-angle Mid-range Telephoto Focal length 15.45 18.52 68.00 F-number 4.12 4.12 4.12 Half angle of view (degrees) 36.92 33.84 11.36 Lens total length 106.62 105.04 126.00 BF 10.68 10.91 12.39 d 5 1.46 3.24 30.85 d11 28.36 22.53 1.79 d17 1.50 1.50 1.50 d22 1.58 2.55 5.63 d26 3.59 4.85 14.40 d28 6.75 6.98 8.45 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 79.42 11.71 2 6 -17.86 12.88 3 12 31.61 11.63 4 18 41.88 8.96 5 23 -33.59 9.18 6 27 40.49 5.09 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 122.665 1.80 1.84666 23.9 2 62.814 5.30 1.59282 68.6 3 1294.672 0.51 4 41.709 4.79 1.67790 55.3 5 127.900 (variable) 6 275.378 1.10 1.90043 37.4 7 14.167 7.13 8 -46.783 0.90 1.59282 68.6 9 36.409 0.30 10 25.512 3.24 1.92286 20.9 11 160.751 (variable) 12 (Aperture) ∞ 1.00 13* 15.032 4.36 1.58313 59.4 14* -81.818 0.12 15 15.816 1.00 1.85883 30.0 16 11.452 5.26 17 ∞ (variable) 18 -197.505 2.58 1.91082 35.3 19 -20.472 1.17 20 -12.108 0.80 1.76182 26.5 21 829.255 4.49 1.59282 68.6 22 -13.485 (variable) 23* -52.870 2.34 1.53110 55.9 24* -25.929 5.63 25 -26.649 0.95 1.76385 48.5 26 68.950 (variable) 27 -372.328 4.87 1.67270 32.1 28 -29.893 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K =-6.86297e-001 A 4= 3.95676e-006 A 6=-2.87862e-008 Page 14 K = 0.00000e+000 A 4= 2.60319e-005 A 6=-1.31617e-007 Page 23 K = 0.00000e+000 A 4= 6.83260e-005 A 6= 6.53637e-007 Page 24 K = 0.00000e+000 A 4= 8.93390e-005 A 6= 5.95344e-007 A 8= 1.48678e-009 Various data Zoom ratio 5.34 Wide-angle Mid-range Telephoto Focal length 15.45 18.65 82.45 F-number 4.12 4.12 4.12 Half angle of view (degrees) 36.92 33.66 9.41 Lens total length 108.02 106.58 128.62 BF 10.68 10.68 10.68 d 5 1.37 3.15 32.39 d11 29.35 23.56 1.50 d17 1.50 1.50 1.50 d22 1.81 2.63 3.27 d26 3.65 5.40 19.62 d28 6.75 6.75 6.75 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 74.20 12.41 2 6 -17.55 12.68 3 12 32.73 11.74 4 18 40.48 9.04 5 23 -36.64 8.93 6 27 48.04 4.87 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 128.562 1.80 1.84666 23.9 2 69.881 4.69 1.59282 68.6 3 371.291 0.51 4 43.230 4.41 1.67790 55.3 5 114.471 (variable) 6 119.585 1.10 1.90043 37.4 7 13.321 7.19 8 -41.783 0.90 1.59282 68.6 9 29.615 0.47 10 24.592 3.20 1.92286 20.9 11 143.448 (variable) 12 (Aperture) ∞ 1.00 13* 14.795 4.53 1.58313 59.4 14* -68.026 0.12 15 14.737 1.00 1.96717 31.7 16 11.040 5.26 17 ∞ (variable) 18 686.021 2.84 1.83280 33.2 19 -19.824 1.17 20 -12.527 0.80 1.80639 22.9 21 -120.766 4.06 1.59282 68.6 22 -13.648 (variable) 23* -38.340 2.04 1.53110 55.9 24* -21.983 4.10 25 -36.369 0.95 1.74321 41.8 26 28.522 (variable) 27 -7925.364 6.24 1.70495 30.2 28 -24.652 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K=-8.67524e-001 A 4= 7.44516e-006 A 6=-7.40032e-008 Page 14 K = 0.00000e+000 A 4= 2.35784e-005 A 6=-1.71153e-007 Page 23 K = 0.00000e+000 A 4=-2.89613e-005 A 6= 4.86273e-007 Page 24 K = 0.00000e+000 A 4= 1.13317e-005 A 6= 4.68511e-007 A 8=-2.81576e-010 Various data Zoom ratio 4.71 Wide-angle Mid-range Telephoto Focal length 13.40 16.58 63.10 F-number 4.12 4.12 4.12 Half angle of view (degrees) 40.91 36.84 12.22 Lens total length 105.91 105.08 129.46 BF 11.16 11.16 11.16 d 5 1.35 3.57 32.68 d11 28.50 22.37 1.50 d17 1.50 1.50 1.50 d22 1.84 3.07 12.02 d26 3.17 5.02 12.22 d28 7.23 7.23 7.23 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 88.73 11.41 2 6 -15.96 12.87 3 12 30.94 11.91 4 18 36.87 8.86 5 23 -28.84 7.09 6 27 35.07 6.24 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 123.193 1.80 1.92286 18.9 2 75.904 4.45 1.57099 50.8 3 358.271 0.51 4 43.537 4.60 1.69680 55.5 5 124.631 (variable) 6 153.453 1.10 1.90043 37.4 7 13.571 6.96 8 -43.112 0.90 1.59282 68.6 9 29.457 0.51 10 24.345 3.30 1.92286 20.9 11 143.033 (variable) 12 (Aperture) ∞ 1.00 13* 15.304 4.34 1.58313 59.4 14* -89.081 0.12 15 15.445 1.00 1.80100 35.0 16 11.246 5.26 17 ∞ (variable) 18 -1122.158 2.88 1.87070 40.7 19 -19.068 1.17 20 -12.191 0.80 1.78472 25.7 21 -195.574 4.37 1.59282 68.6 22 -13.512 (variable) 23* -38.788 2.31 1.53110 55.9 24* -22.174 3.84 25 -41.221 0.95 1.79952 42.2 26 35.000 (variable) 27 -211.869 5.56 1.72151 29.2 28 -25.405 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K =-1.08007e+000 A 4= 2.29312e-005 A 6= 4.36460e-008 Page 14 K = 0.00000e+000 A 4= 3.29321e-005 A 6=-7.86162e-008 Page 23 K = 0.00000e+000 A 4=-1.71454e-006 A 6= 8.45857e-007 Page 24 K = 0.00000e+000 A 4= 3.84615e-005 A 6= 7.60401e-007 A 8= 7.38480e-010 Various data Zoom ratio 4.71 Focal length 13.40 16.41 63.10 F-number 4.12 4.12 4.12 Half angle of view (degrees) 40.91 37.12 12.22 Lens length 106.63 104.96 129.26 BF 12.28 12.28 12.28 d 5 1.35 2.78 31.66 d11 28.54 22.29 1.50 d17 1.50 1.50 1.50 d22 2.01 3.12 10.20 d26 3.22 5.27 14.40 d28 8.35 8.35 8.35 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 84.56 11.36 2 6 -16.13 12.78 3 12 33.01 11.72 4 18 34.98 9.22 5 23 -32.56 7.10 6 27 39.51 5.56 [Numerical Example 6] Unit: mm Surface Data Surface number rd nd νd 1 121.973 1.80 1.84666 23.9 2 62.240 5.27 1.59282 68.6 3 2370.018 0.51 4 40.512 4.80 1.67790 55.3 5 116.602 (variable) 6 -4421.461 1.10 1.90043 37.4 7 14.963 5.98 8 -46.336 0.90 1.59282 68.6 9 42.247 0.30 10 26.906 3.07 1.92286 20.9 11 250.704 (variable) 12 (Aperture) ∞ 1.00 13* 14.793 4.15 1.58313 59.4 14* -82.688 0.12 15 15.627 1.00 1.85026 32.3 16 11.273 5.26 17 ∞ (variable) 18 -166.576 2.46 1.91082 35.3 19 -21.613 1.17 20 -12.207 0.80 1.76182 26.5 21 -4122.514 4.40 1.59282 68.6 22 -13.470 (variable) 23* -54.960 1.98 1.53110 55.9 24* -27.894 6.00 25 -22.683 0.95 1.74400 44.8 26 163.409 (variable) 27 4121.176 4.85 1.74077 27.8 28 -36.742 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K =-1.02703e+000 A 4= 1.61231e-005 A 6=-2.00853e-008 Page 14 K = 0.00000e+000 A 4= 2.17226e-005 A 6=-1.19856e-007 Page 23 K = 0.00000e+000 A 4= 7.88762e-005 A 6= 5.70055e-007 Page 24 K = 0.00000e+000 A 4= 8.81635e-005 A 6= 5.49087e-007 A 8= 9.52094e-010 Various data Zoom ratio 4.90 Wide-angle Mid-range Telephoto Focal length 18.00 21.06 88.20 F-number 4.12 4.12 4.12 Half angle of view (degrees) 32.82 30.52 8.80 Lens total length 108.02 105.96 127.32 BF 11.42 11.42 11.42 d 5 2.30 3.74 33.20 d11 28.11 22.64 1.86 d17 1.50 1.50 1.50 d22 1.68 3.03 1.20 d26 5.15 5.77 20.28 d28 7.49 7.49 7.49 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 73.06 12.37 2 6 -18.56 11.35 3 12 32.41 11.53 4 18 44.34 8.83 5 23 -38.31 8.93 6 27 49.19 4.85 [Numerical Example 7] Unit: mm Surface Data Surface number rd nd νd 1 117.543 1.80 1.84666 23.9 2 61.553 5.83 1.59282 68.6 3 -59223.600 0.51 4 40.307 4.71 1.67790 55.3 5 108.687 (variable) 6 1997.558 1.10 1.90043 37.4 7 15.149 6.21 8 -43.585 0.90 1.59282 68.6 9 46.718 0.30 10 28.366 3.19 1.92286 20.9 11 351.325 (variable) 12 (Aperture) ∞ 1.00 13* 14.604 4.22 1.58313 59.4 14* -96.588 0.12 15 15.838 1.00 1.85026 32.3 16 11.215 5.26 17 ∞ (variable) 18 -229.646 2.44 1.91082 35.3 19 -22.941 1.17 20 -12.455 0.80 1.76182 26.5 21 -473.052 4.30 1.59282 68.6 22 -13.598 (variable) 23* -53.534 2.53 1.53110 55.9 24* -26.226 6.49 25 -23.985 0.95 1.74400 44.8 26 95.541 (variable) 27 320.518 4.75 1.74077 27.8 28 -42.406 (variable) 29 ∞ 1.10 1.51633 64.1 30∞3.20 Image plane ∞ Aspheric data Page 13 K =-1.16112e+000 A 4= 1.83685e-005 A 6= 9.36262e-009 Page 14 K = 0.00000e+000 A 4= 1.35276e-005 A 6=-6.47677e-008 Page 23 K = 0.00000e+000 A 4= 2.25280e-005 A 6= 1.15149e-007 Page 24 K = 0.00000e+000 A 4= 3.07670e-005 A 6= 1.07050e-007 A 8= 1.12991e-010 Various data Zoom ratio 5.44 Wide-angle Mid-range Telephoto Focal length 18.00 21.39 98.00 F-number 4.12 4.12 4.12 Half angle of view (degrees) 32.82 30.13 7.94 Lens length 110.12 108.22 129.98 BF 11.73 11.73 11.73 d 5 2.30 3.88 34.40 d11 29.50 23.68 1.50 d17 1.50 1.50 1.50 d22 1.47 2.58 -1.50 d26 4.06 5.28 22.78 d28 7.79 7.79 7.79 Zoom lens group data Lens group First surface Focal length Lens construction length 1 1 72.30 12.85 2 6 -19.00 11.71 3 12 33.92 11.60 4 18 44.49 8.70 5 23 -38.21 9.97 6 27 50.84 4.75 The various values ​​in each numerical example are summarized in Table 1 below.

[0063] [Table 1]

[0064] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of each embodiment as an imaging optical system will be described with reference to Fig. 15. In Fig. 15, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the zoom lenses described in Embodiments 1 to 7. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body and receives and photoelectrically converts an optical image formed by the imaging optical system 11. The camera body 10 may be a so-called single-lens reflex camera having a quick-turn mirror, or a so-called mirrorless camera having no quick-turn mirror.

[0065] In this way, by applying the zoom lens of each embodiment to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained. [Imaging system] An imaging system (surveillance camera system) may be configured that includes the zoom lens of each embodiment and a control unit that controls the zoom lens. 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 stabilization. In this case, the control unit does not need to be configured integrally with the zoom lens; the control unit may be configured separately from the zoom lens. For example, a control unit (control device) located far from the drive units that drive each lens of the zoom lens may include a transmission unit that sends control signals (commands) to control the zoom lens. Such a control unit allows the zoom lens to be remotely controlled.

[0066] Alternatively, the control unit may be provided with an operation unit such as a controller or buttons for remotely operating the zoom lens, thereby controlling the zoom lens in response to user input to the operation unit. For example, the operation unit may be provided with a zoom-in button and a zoom-out button. In this case, the control unit may be configured to send a signal to a zoom lens driver so that the zoom magnification increases when the user presses the zoom-in button, and decreases when the user presses the zoom-out button.

[0067] The imaging system may also have a display unit such as a liquid crystal panel that displays information (movement state) related to the zoom of the zoom lens. Information related to the zoom of the zoom lens may be, for example, the zoom magnification (zoom state) or the movement amount (movement state) of each lens group. In this case, the user can remotely operate the zoom lens via the operation unit while viewing the information related to the zoom of the zoom lens displayed on the display unit. In this case, the display unit and operation unit may be integrated by using, for example, a touch panel.

[0068] Although the preferred embodiments and examples of the present invention have been described above, 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 of the present invention. [Explanation of symbols]

[0069] L1 First lens group L2 Second lens group

Claims

1. A zoom lens comprising, arranged in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent group including a focus lens group that moves during focusing, wherein the spacing between adjacent lens groups changes during zooming, the subsequent lens group comprises, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, and a sixth lens group having a positive refractive power; the focus lens group includes a positive lens and a negative lens, Let Lfpn be the air gap between the positive lens and the negative lens, Tf be the distance on the optical axis from the lens surface of the focus lens group closest to the object to the lens surface of the focus lens group closest to the image when focusing at infinity, ff be the focal length of the focus lens group, fw be the focal length of the zoom lens at the wide-angle end, ft be the focal length of the lens group arranged adjacent to the focus lens group on the object side, fo be the focal length of the sixth lens group, and fp be the focal length of the sixth lens group. 0.50<Lfpn / Tf<0.75 -1.5<ff / √(fw×ft)<-0.7 -1.0<ff / fo<-0.5 -1.0<ff / fp<-0.5 A zoom lens characterized by satisfying the following conditional expressions:

2. When the radius of curvature of the lens surface of the focus lens group closest to the object side is Rfobj and the radius of curvature of the lens surface of the focus lens group closest to the image side is Rfimg, -0.6<(Rfobj+Rfimg) / (Rfobj-Rfimg)<0.2 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the Abbe number of the positive lens is νfn and the Abbe number of the negative lens is νfp, 0<|νfn−νfp|<15 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. 4. The zoom lens according to claim 1, wherein the positive lens element, at least one of whose surfaces is aspherical and included in the focus lens group, has a shape in which its positive power weakens at its periphery.

5. When the average refractive index of the lenses included in the focus lens group is ndfav, 1.50<ndfav<1.75 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. 6. The zoom lens according to claim 1, wherein at least a portion of the lens group arranged adjacent to the image side of the second lens group in the subsequent group moves in a direction including a component perpendicular to the optical axis of the zoom lens when correcting image plane movement of the subject image.

7. 7. The zoom lens according to claim 1, wherein the effective image circle diameter at the wide-angle end is smaller than the effective image circle diameter at the telephoto end.

8. 8. The zoom lens according to claim 1, wherein the first lens group comprises a cemented lens formed by cementing together a negative meniscus lens having a convex lens surface facing the object side and a positive lens having a convex lens surface facing the object side, and a positive meniscus lens having a convex lens surface facing the object side.

9. 9. The zoom lens according to claim 1, wherein the second lens group comprises a negative meniscus lens having a convex lens surface facing the object side, a negative lens having concave lens surfaces on both sides, and a positive lens having a convex lens surface facing the object side.

10. 10. The zoom lens according to claim 1, wherein the fifth lens group is the focus lens group.

11. 11. The zoom lens according to claim 1, wherein the third lens group comprises a positive lens having convex lens surfaces on both sides, and a negative meniscus lens having a convex lens surface on the object side.

12. 12. The zoom lens according to claim 1, wherein the fourth lens group comprises a positive lens having a convex lens surface facing the image side, and a cemented lens formed by cementing together a negative meniscus lens having a concave lens surface facing the object side and a positive lens having a convex lens surface facing the image side.

13. 13. The zoom lens according to claim 1, wherein the fifth lens group comprises a positive meniscus lens having a convex lens surface on the image side, and a negative lens having concave lens surfaces on both sides.

14. 14. The zoom lens according to claim 1, wherein the sixth lens group is made up of a positive meniscus lens having a convex lens surface on the image side.

15. A zoom lens according to any one of claims 1 to 14; and an image sensor that receives an image formed by the zoom lens.

Images