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

Abstract

To provide a zoom lens which comprises a compact system as a whole, has an imaging area that changes from a circumferential fish eye to a diagonal fish eye, allows for shooting at a wide range of imaging angles of view at the telephoto end, and offers high optical performance over an entire zoom range.SOLUTION: A zoom lens comprises a first lens group having negative refractive power and a rear group comprising one or more lens groups, arranged in order from the object side to the image side, and is configured such that distances between adjacent lenses change when zooming. Positions of the first lens group and the one or more lens groups can be set at first, second, and third zoom positions. At the first and second zoom positions, angles of view at a first image height and a second image height is 160° or greater. At the third zoom position, distortion aberration at a first image height is -30% or greater. The first image height, the second image height, a total length at the wide-angle end, and a focal length at the wide-angle end are appropriately set.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a zoom lens, and a lens apparatus and an imaging apparatus having the same. [Background technology]

[0002] Among optical systems, fisheye lenses are known as ones that have a particularly wide angle of view, and they achieve this by intentionally generating distortion aberration. Conventionally, fisheye zoom lenses that provide a circular fisheye system at the shortest focal length and a diagonal fisheye system at the longest focal length are known (Patent Document 1). Also known is a zoom lens that provides a diagonal fisheye system at the shortest focal length and maintains a standard imaging angle of view at the longest focal length (Patent Document 2). In addition, a relatively high zoom ratio zoom lens is known that provides an imaging angle of view of approximately 180° from the shortest focal length to the intermediate focal length and maintains a standard imaging angle of view at the longest focal length (Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-156507 A [Patent Document 2] JP 2012-123412 A [Patent Document 3] JP 2017-003646 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, optical systems used in image pickup apparatuses are required to have good optical performance and a small overall lens length. In addition, there is a demand for vehicle-mounted cameras and surveillance cameras that can capture images with a wide angle of view and with fewer blind spots, and fisheye lenses that have a particularly wide angle of view are attracting attention. There is also a demand for wide-angle lenses with good correction of distortion aberration.

[0005] Although Patent Document 1 is capable of imaging using the circular fisheye method and the diagonal fisheye method, it has a problem in that it is not possible to obtain an image with little distortion aberration. Although Patent Document 2 enables imaging at a wide angle from a diagonal fisheye to a standard angle of view, it has a problem in that it cannot perform imaging using a circular fisheye method. In Patent Document 3, a large zoom ratio enables imaging at a standard angle of view at the maximum focal length, so the entire system becomes large.

[0006] An object of the present invention is to provide a zoom lens that has a small overall system, an imaging area that changes from a circular fisheye to a diagonal fisheye, can capture images over a wide range of imaging angles at the longest focal length, and has high optical performance over the entire zoom range. [Means for solving the problem]

[0007] The zoom lens of the present invention comprises: a first lens group having negative refractive power, arranged in order from the object side to the image side; 4 a rear group having one or more lens groups, and the spacing between adjacent lens groups changes during magnification change, the rear group has a second lens group arranged closest to the object in the rear group, and a third lens group having positive refractive power arranged adjacent to the image side of the second lens group, the rear group including an aspherical lens having a negative aspherical amount, The first lens group and the Arranged in the rear group The position of the lens group can be set to a first zoom position, a second zoom position, and a third zoom position, the first zoom position being a wide-angle end position, the second zoom position being an intermediate zoom position, and the third zoom position being a telephoto end position, and at each of the first and second zoom positions, in The angle of view is 160° or more. When the zoom lens is attached to a camera body having an image sensor, the first zoom position corresponds to a circular fisheye method, and the second zoom position corresponds to a diagonal fisheye method, The distance on the optical axis from the lens surface closest to the object of the zoom lens at the wide-angle end to the image plane is Lw, the focal length of the zoom lens at the wide-angle end is fw, and the amount of distortion at the maximum image height at the telephoto end based on the central projection is Vt Among the aspherical lenses, the aspherical amount of the surface of the aspherical lens arranged closest to the image side is Arl, the effective diameter of the light beam is Eal, and the refractive index is Ndl. When 5.0 <Lw / fw<22.5 -30% <Vt<30% -0.1000 <Arl / Eal×Ndl<-0.0003 The present invention is characterized in that the following conditional expression is satisfied: Effect of the Invention

[0008] According to the present invention, a zoom lens can be obtained which has a small overall system, an imaging area that changes from a circular fisheye to a diagonal fisheye, is capable of imaging over a wide range of imaging angles at the longest focal length, and provides high optical performance over the entire zoom range. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of the first embodiment at the minimum focal length when focusing on infinity. [Diagram 2] 5A to 5C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 1. [Diagram 3] FIG. 11 is a cross-sectional view of the second embodiment at the shortest focal length when focusing on infinity. [Figure 4] 11A to 11C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 2. [Diagram 5] FIG. 11 is a cross-sectional view of the third embodiment at the minimum focal length when focusing on infinity. [Figure 6] 11A to 11C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 3. [Figure 7] FIG. 11 is a cross-sectional view of the fourth embodiment at the shortest focal length when focusing on infinity. [Figure 8] 11A to 11C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 4. [Figure 9] FIG. 13 is a cross-sectional view of the fifth embodiment at the minimum focal length when focusing on infinity. [Figure 10] 13A to 13C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 5. [Figure 11]FIG. 23 is a cross-sectional view of Example 6 at the shortest focal length when focusing on infinity. [Figure 12] 13A to 13C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 6. [Figure 13] FIG. 23 is a cross-sectional view of Example 7 at the shortest focal length when focusing on infinity. [Figure 14] 13A to 13C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 7. [Figure 15] FIG. 23 is a cross-sectional view of Example 8 at the shortest focal length when focusing on infinity. [Figure 16] 13A to 13C are aberration diagrams at the shortest focal length, the intermediate focal length, and the longest focal length of Example 8. [Figure 17] 2 is a schematic diagram of an image circle of the zoom lens of the present invention and an image sensor. [Figure 18] FIG. 4 is an explanatory diagram of an aspheric shape. [Figure 19] 1 is a schematic diagram of an imaging device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a zoom lens and an image pickup apparatus having the same according to the present invention will be described with reference to the accompanying drawings. The zoom lens of each embodiment is an optical system used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras.

[0011] Fig. 1 is a lens cross-sectional view of Example 1 of the present invention at the shortest focal length when focusing on infinity. Figs. 2(A), (B), and (C) are aberration diagrams of the zoom lens of Example 1 at the shortest focal length (wide-angle end), intermediate focal length, and longest focal length (telephoto end), respectively. Example 1 is a zoom lens with a zoom ratio of 2.9 and an F-number of about 4.

[0012] 3 is a lens cross-sectional view of Example 2 of the present invention at the shortest focal length when focusing on infinity. Figures 4(A), (B), and (C) are aberration diagrams of the zoom lens of Example 2 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 2 is a zoom lens with a zoom ratio of 2.9 and an F-number of about 4.

[0013] Fig. 5 is a lens cross-sectional view of Example 3 of the present invention at the shortest focal length when focusing on infinity. Figs. 6(A), (B), and (C) are aberration diagrams of the zoom lens of Example 3 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 3 is a zoom lens with a zoom ratio of 2.8 and an F-number of about 4.

[0014] 7 is a lens cross-sectional view of Example 4 of the present invention at the shortest focal length when focusing on infinity. Figures 8(A), (B), and (C) are aberration diagrams of the zoom lens of Example 4 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 4 is a zoom lens with a zoom ratio of 3.0 and an F-number of about 4.

[0015] Fig. 9 is a lens cross-sectional view of Example 5 of the present invention at the shortest focal length when focusing on infinity. Figs. 10(A), (B), and (C) are aberration diagrams of the zoom lens of Example 5 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 5 is a zoom lens with a zoom ratio of 3.3 and an F-number of about 4.

[0016] Fig. 11 is a lens cross-sectional view of Example 6 of the present invention at the shortest focal length when focusing on infinity. Figs. 12(A), (B), and (C) are aberration diagrams of the zoom lens of Example 6 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 6 is a zoom lens with a zoom ratio of 3.0 and an F-number of about 4.

[0017] Fig. 13 is a lens cross-sectional view of Example 7 of the present invention at the shortest focal length when focusing on infinity. Figs. 14(A), (B), and (C) are aberration diagrams of the zoom lens of Example 7 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 7 is a zoom lens with a zoom ratio of 2.8 and an F-number of about 4.

[0018] Fig. 15 is a lens cross-sectional view of Example 8 of the present invention at the shortest focal length when focusing on infinity. Figs. 16(A), (B), and (C) are aberration diagrams of the zoom lens of Example 8 at the shortest focal length, intermediate focal length, and longest focal length, respectively. Example 8 is a zoom lens with a zoom ratio of 3.3 and an F-number of about 4.

[0019] 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 to have multiple lens groups. In this specification, a lens group is a group of lenses that move or stand still as a unit during zooming (variable magnification) and focusing. That is, in the zoom lens of each embodiment, the distance between adjacent lens groups changes during zooming from the shortest focal length to the longest focal length. Note that the lens group may be composed of one lens or multiple lenses. The lens group may also include an aperture stop.

[0020] If i is the order from the object side (i is a natural number), Li indicates the i-th lens group. The zoom lens L0 of each embodiment is made up of a plurality of lens groups Li.

[0021] Additionally, SP is an aperture stop. IP is an image plane, and when the zoom lens of each embodiment is used as the photographing optical system of a digital still camera or digital video camera, the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed thereon. When the zoom lens of each embodiment is used as the photographing optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is disposed on the image plane IP.

[0022] Moreover, the zoom lens L0 of each embodiment is configured to move the second lens group during focusing. Furthermore, the zoom lens L0 of embodiments 1 and 2 is configured to move one of the lens groups Lfl after the third lens group. Hereinafter, in the zoom lens L0 of embodiments 1 and 2, the lens group closest to the object that moves during focusing will also be referred to as the lens group Lfo. The arrows shown in each lens cross-sectional view indicate the movement direction of the lens group during focusing from infinity to a close distance. The lens group Lfo and the lens group Lfl move on different trajectories during focusing. This makes it possible to suppress the variation in field curvature during focusing.

[0023] 2, 4, 6, 8, 10, 12, 14, and 16 are aberration diagrams when focusing at infinity for the zoom lenses of Examples 1 to 8. In each aberration diagram, (A) is the aberration diagram at the shortest focal length, (B) is the aberration diagram at the intermediate focal length, and (C) is the aberration diagram at the longest focal length.

[0024] 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 sagittal image plane, and ΔM shows the meridional image plane. For distortion aberration, the value at the d-line when the equal solid angle projection method is used as the standard at the shortest and intermediate focal lengths, and the value at the d-line when the central projection method is used as the standard at the longest focal length. The chromatic aberration diagram shows the amount of chromatic aberration at the g-line. ω is the paraxial half angle of view (°).

[0025] When a fisheye lens is attached to an imaging device having an image sensor, there is a method that forms a nearly circular subject image while maintaining an imaging angle of view of approximately 180° in all directions (called the "circular fisheye method"). There is also a method that maintains a full imaging angle of view of approximately 180° in the diagonal direction of the image sensor (called the "diagonal fisheye method"). Note that in this invention, the shortest focal length among the focal lengths that result in the diagonal fisheye method is defined as the intermediate focal length. Fisheye lenses generally use a projection method that satisfies the following formula, where Y is the image height, f is the focal length, and ω is the half angle of view. Y=2f×tan(ω / 2) ···Stereoscopic projection Y=fω...equidistant projection Y=2f×sin(ω / 2) ···Equisolid angle projection Y=f×sin(ω) ...orthogonal projection In addition, lenses other than fisheye lenses generally use the following projection method: Y=ftan(ω) ···Center projection The zoom lens according to the present invention is designed assuming equal solid angle projection at the shortest focal length.

[0026] 17 is a schematic diagram of an image circle formed by a zoom lens according to the present invention and an imaging surface of an imaging element used in an imaging apparatus, in which IM is a rectangular imaging element whose imaging surface has a diagonal length of 2×H.

[0027] In Fig. 17, ISw represents the image circle at the shortest focal length, and the maximum image height Yw is approximately equal to the radius of the image circle ISw. The maximum image height Yw is also approximately equal to half the length DS of the short side of the rectangular image sensor IM. ISm represents the image circle at the intermediate focal length, and the maximum image height Ym at the intermediate focal length is approximately equal to half the diagonal length H of the image sensor IM.

[0028] Next, the definition of the aspheric amount formed on the lens surface according to the present invention will be described. Aspheric amount Ar represents the maximum deviation amount of the aspheric surface Ra from the reference spherical surface Rref, as shown in FIG. 18. The radius (radius of curvature) of the reference spherical surface Rref is the radius of the sphere determined by the vertex of the surface and the effective diameter of the light beam of the surface. The deviation direction of the aspheric surface Ra from the reference spherical surface Rref is defined as a positive aspheric amount when the medium is piled up relative to the reference spherical surface Rref, and as a negative aspheric amount when the medium is removed. For example, the aspheric surface Ra shown in FIG. 18 has a positive aspheric amount. That is, the aspheric surface having the aspheric amount according to the present invention satisfies the following conditional expressions (xa) and (xb), where Ar is the aspheric amount, Ea is the effective diameter of the light beam of the aspheric surface, and Nd is the refractive index of the material of the aspheric lens. 0.0003 <Ar / Ea×Nd ···(xa) -0.0003>Ar / Ea×Nd (xb)

[0029] Aspheric surfaces that deviate from conditional expressions (xa) and (xb) have a small aspheric effect and do not fully achieve the effects of the present invention, and are therefore not included in the aspheric surfaces according to the present invention. Next, the zoom lens of each embodiment will be described in detail.

[0030] The zoom lens of Example 1 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with negative refractive power, and a fifth lens group L5 with positive refractive power.

[0031] During zooming from the wide-angle end to the telephoto end, the first lens group L1 and the second lens group L2 move on a concave locus toward the object side. The third lens group L3 moves linearly toward the object side. The fourth lens group L4 and the fifth lens group L5 move on a convex locus toward the object side. During focusing, the second lens group L2 (Lfo) and the fourth lens group L4 (Lfl) move on different loci.

[0032] The zoom lens of Example 2 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power.

[0033] When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves on a concave locus toward the object side. The third lens group L3 moves linearly toward the object side. The second lens group L2 and the fourth lens group L4 move toward the object side. The fifth lens group L5 moves on a convex locus toward the object side. When focusing, the second lens group L2 (Lfo) and the fourth lens group L4 (Lfl) move on different loci.

[0034] The zoom lens of Example 3 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with positive refractive power.

[0035] When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves along a concave locus toward the object side. The third lens group L3 moves linearly toward the object side. The second lens group L2 and the fourth lens group L4 move toward the object side. The fifth lens group L5 moves along a convex locus toward the object side. The second lens group L2 moves during focusing.

[0036] The zoom lens of Example 4 is a six-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with positive refractive power, and a sixth lens group L6 with positive refractive power.

[0037] When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves along a concave locus toward the object side. The third lens group L3 moves in a straight line toward the object side. The second lens group L2 and the fourth lens group L4 move toward the object side. The fifth lens group L5 and the sixth lens group L6 move along a concave locus toward the object side. The second lens group L2 moves during focusing.

[0038] The zoom lens of Example 5 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with positive refractive power.

[0039] During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the image side. The third lens group L3 moves linearly toward the object side. The second lens group L2, the fourth lens group L4, and the fifth lens group L5 move toward the object side. During focusing, the second lens group L2 moves.

[0040] The zoom lens of Example 6 is a three-group zoom lens consisting of a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, and a third lens group L3 with positive refractive power, arranged in that order from the object side to the image side.

[0041] During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves along a concave path toward the object side. The second lens group L2 moves in a straight line toward the object side. The third lens group L3 moves toward the image side. During focusing, part of the second lens group L2 moves.

[0042] The zoom lens of Example 7 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 having negative refractive power, a second lens group L2 having positive refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having positive refractive power.

[0043] When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves along a concave locus toward the object side. The third lens group L3 moves in a straight line toward the object side. The second lens group L2 and the fourth lens group L4 move toward the object side. The fifth lens group L5 moves along a concave locus toward the object side. The second lens group L2 moves during focusing.

[0044] The zoom lens of Example 8 is a five-group zoom lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with negative refractive power, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the image side. The third lens group L3 moves linearly toward the object side. The second lens group L2, the fourth lens group L4, and the fifth lens group L5 move toward the object side. During focusing, the second lens group L2 moves.

[0045] Next, the characteristic configuration of the zoom lens of each embodiment will be described. The zoom lens of the present invention is composed of a first lens group having negative refractive power and a rear group having one or more lens groups, which are arranged in that order from the object side to the image side, and the distance between adjacent lens groups changes during zooming (variable magnification). The positions of the first lens group and the one or more lens groups can be set to a first zoom position, a second zoom position, and a third zoom position, and at the first and second zoom positions, the angle of view at the first image height and the second image height is 160° or more, and at the third zoom position, the distortion at the first image height is -30% or more. Let H1 be the first image height, H2 be the second image height, Lw be the total length of the zoom lens at the shortest focal length (wide-angle end), and fw be the focal length of the entire system at the shortest focal length. 1.5 5.0 <Lw / fw<22.5 ···(1) The present invention is characterized in that the following conditional expressions are satisfied:

[0046] Conditional formula (1) specifies the total length Lw of the zoom lens at the shortest focal length in terms of the focal length fw of the entire system at the shortest focal length. If Lw becomes small beyond the lower limit of conditional formula (1), the focal length of each group becomes too short, which increases off-axis aberrations and makes it difficult to obtain good performance, which is undesirable. Conversely, if fw becomes large beyond the lower limit of conditional formula (1), it is undesirable because a sufficient angle of view cannot be obtained at the shortest focal length.

[0047] If Lw becomes large beyond the upper limit of condition (1), the overall length becomes too long, which is undesirable, or if fw becomes small beyond the upper limit of condition (1), the focal length of each group becomes too long, which increases off-axis aberrations such as lateral chromatic aberration, making it difficult to obtain high optical performance. Furthermore, it is preferable that the numerical range of conditional expression (1) is within the range of the following conditional expression (1a). 8 <Lw / fw<20 ···(1a) It is further preferable that the numerical range of conditional expression (1) satisfies the range of the following conditional expression (1b). 12 <Lw / fw<19 ···(1b)​

[0048] 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 (2) to (7). -2.1 <f1 / fw<-0.5 ···(2) -0.8 <f1 / ft<0.0 ···(3) 1.0<(R1a+R1b) / (R1a-R1b)<4.5 (4) 0.31 <skw / skt<1.20 ···(5) 1.5 <ft / fw<4.0 ···(6) 1.6 <G1Nd<2.5 ···(7)

[0049] Next, the technical meaning of each of the above conditional expressions will be explained. Conditional formula (2) specifies the value of the ratio of the focal length f1 of the first lens group L1 to the focal length fw of the entire system at the shortest focal length. If f1 becomes small beyond the lower limit of conditional formula (2), the refractive power of the first lens group L1 becomes too strong, and off-axis aberrations such as lateral chromatic aberration increase, making it difficult to obtain high optical performance. If f1 becomes large beyond the upper limit of conditional formula (2), the amount of movement of the first lens group L1 must be increased to obtain high magnification, which is undesirable because it increases the overall length.

[0050] Conditional formula (3) specifies the value of the ratio of the focal length f1 of the first lens group L1 to the focal length ft of the entire system at the longest focal length. If f1 becomes small beyond the lower limit of conditional formula (3), the refractive power of the first lens group becomes too strong, increasing off-axis aberrations such as lateral chromatic aberration, making it difficult to obtain high optical performance. If f1 becomes large beyond the upper limit of conditional formula (3), the amount of movement of the first lens group L1 must be increased to obtain high magnification, which undesirably increases the overall length.

[0051] Conditional formula (4) specifies the lens shape (shape factor) of the meniscus-shaped first negative lens included in the first lens group L1, with the radius of curvature of the object side surface of the first negative lens being R1a and the radius of curvature of the image side surface of the first negative lens being R1b. If the lower limit of conditional formula (4) is exceeded, the refractive power of the first negative lens becomes too strong, making it difficult to obtain high optical performance. If the upper limit of conditional formula (4) is exceeded, the refractive power of the first negative lens becomes too weak, making it difficult to obtain a wide range of imaging angles of view.

[0052] Conditional formula (5) specifies the value of the ratio of the back focus skw at the shortest focal length to the back focus skt at the longest focal length. If skw is reduced beyond the lower limit of conditional formula (5), the distance between the lens and the camera becomes too small, which is undesirable as the degree of freedom in mechanical layout is reduced. Alternatively, if skt is increased beyond the lower limit of conditional formula (5), the overall lens length becomes too large, which is undesirable. If skw is increased beyond the upper limit of conditional formula (5), the overall lens length becomes too large, which is undesirable. Alternatively, if skt is reduced beyond the upper limit of conditional formula (5), the distance between the lens and the camera becomes too small, which is undesirable as the degree of freedom in mechanical layout is reduced.

[0053] Conditional formula (6) specifies the ratio of the focal length ft of the entire system at the longest focal length to the focal length fw of the entire system at the shortest focal length. If fw is reduced beyond the upper limit of conditional formula (6), the focal length of each group becomes too strong, increasing off-axis aberrations, making it difficult to obtain high optical performance. Alternatively, if ft is increased beyond the upper limit of conditional formula (6), the wide-angle imaging range becomes narrow, which is undesirable. If fw is increased beyond the lower limit of conditional formula (6), a sufficient angle of view cannot be obtained at the shortest focal length, which is undesirable. Alternatively, if ft is reduced beyond the lower limit of conditional formula (6), the focal length of each group becomes too strong, increasing off-axis aberrations such as distortion at the longest focal length, which is undesirable.

[0054] Conditional expression (7) specifies the refractive index of the glass material used for the first lens G1, which is located closest to the object in the first lens group L1. Conditional expression (7) is intended to reduce the occurrence of curvature of field, and if the condition satisfies the range of conditional expression (7), it is easy to correct the curvature of field.

[0055] In the zoom lens, it is preferable that a lens group including an aspherical lens having a negative aspherical amount or a lens group having a negative refractive power is present on the image side of the first lens group L1, and when the distance at the longest focal length from the vertex on the optical axis of the lens closest to the image side of the lens group closest to the image side among these lenses to the imaging plane is D, 0.00 <D / H1<2.28 ···(8) It is preferable to satisfy the following formula: If D becomes smaller than the lower limit of conditional formula (8), the distance between the lens having a negative effect at the maximum focal length and the camera becomes too close, reducing the freedom of mechanical layout. If D becomes larger than the upper limit of conditional formula (8), the distance between the lens having a negative effect at the maximum focal length and the image plane becomes too large, making it difficult to correct distortion.

[0056] Moreover, when the zoom lens has a lens group including an aspherical lens with a negative aspherical amount in a group closer to the image side than the first group, the aspherical amount of the surface (surface As) with the largest negative aspherical amount of the aspherical lens with the negative aspherical amount arranged closest to the image side is represented as Arl, the effective diameter of the light beam is represented as Eal, and the refractive index of the material of the aspherical lens is represented as Ndl, -0.1000 <Arl / Eal×Ndl<-0.0003 ···(9) It is desirable to satisfy the following conditional expression. If the lower limit of conditional expression (9) is exceeded, the rate of change of the aspherical system angle of incidence of the aspherical surface becomes too large, making it difficult to mold the aspherical surface. If the upper limit of conditional expression (9) is exceeded, the aspherical effect obtained becomes small, which is undesirable.

[0057] Here, the zoom lens L0 of Examples 1 to 8 is designed to allow barrel distortion at the longest focal length. Assuming that electronic aberration correction technology based on recent technological developments is used, image distortion caused by distortion can be corrected by this image processing technology. Therefore, the storage device (storage unit) attached to these zoom lenses L0 has information on the design value of the amount of distortion of the zoom lens L0, and an electronic image captured using the imaging optical system can be corrected by image processing in an arbitrary image processing unit (for example, a CPU attached to an imaging device such as a camera body) attached to the zoom lens L0 using the design value of the amount of distortion.

[0058] For this reason, it is preferable that the lens device sends a signal for correcting the barrel distortion at the maximum focal length to the image processing unit, and at the minimum focal length, a more ideal equisolid angle projection method can be achieved by image processing.

[0059] Furthermore, when performing image processing, the maximum distortion correction amount when eliminating distortion in the equal solid angle projection method at the shortest focal length is Clw, and the maximum distortion correction amount when eliminating distortion in the central projection method at the longest focal length is Clt, |Clw / Clt|<1 (10) It is preferable to perform distortion correction so as to satisfy the following condition:

[0060] Conditional expression (10) specifies the ratio of the maximum distortion correction amount Clw at the shortest focal length to the maximum distortion correction amount Clt at the longest focal length. If Clw increases beyond the upper limit of conditional expression (10), image quality at the shortest focal length will degrade, which is not preferable. Alternatively, if Clt decreases beyond the upper limit of conditional expression (10), electronic distortion correction cannot be performed sufficiently at the longest focal length, and the amount of distortion will be too large for use as a wide-angle lens, which is not preferable.

[0061] Here, it is preferable that the lens device is mounted on an imaging device having an imaging element that receives an image formed by the lens device. The imaging area of ​​the imaging element is rectangular, and at any focal length of the zoom lens, the maximum image height is lower than half of any side of the imaging area, and at any focal length, the maximum image height is equal to or more than half the diagonal length of the imaging area, and the zoom lens has a zoom range that includes a focal length at which the maximum image height is equal to or less than half the short side of the rectangular imaging area, and a focal length at which the maximum image height is equal to or more than half the diagonal length of the rectangular imaging area. In this case, when the imaging half angle of view at the shortest focal length at which the image height is determined by half the diagonal length of the rectangular imaging area is ωw, the half length of the diagonal length of the imaging element is H, the maximum image height at the shortest focal length is Yw, the amount of distortion aberration at the maximum image height at the longest focal length is Vt, and the focal length of the first lens group is f1, 80°<ωw<110° (11) 1.4 <H / Yw<2.6 ···(12) -30% <Vt<30% ···(13) -2.8 <H / f1<-0.5 ···(14) It is desirable to satisfy the following condition:

[0062] Conditional formula (11) specifies the half angle of view for the shortest focal length. Fisheye lenses are capable of capturing images over a wide range of angles of view by allowing distortion, and are primarily required to have an image capturing angle of view of 80° or more. If the lower limit of conditional formula (11) is exceeded, the angle of view becomes narrow and it may not be possible to capture images under the desired conditions, which is undesirable. If the upper limit of conditional formula (11) is exceeded, the image capturing angle of view becomes too wide, causing the refractive power of the first lens group to become too strong, making it difficult to obtain high optical performance.

[0063] Conditional formula (12) defines half the diagonal length H of the rectangular image sensor IM and the maximum image height Yw at the shortest focal length. The aspect ratio of the image sensor IM can be various, such as 4:3 or 16:9. In the first to eighth embodiments, the aspect ratio of the image sensor IM is 4:3. If Yw is increased beyond the lower limit of conditional formula (12), Yw exceeds the short side SS of the rectangular image sensor IM, and an approximately circular subject image is not formed, which is not preferable. If Yw is decreased beyond the upper limit of conditional formula (12), the peripheral portion of the imaging area where the subject image is not formed becomes too large, which is not preferable. Conditional formula (13) defines the amount of distortion at the maximum image height at the longest focal length.

[0064] If Vt becomes small by exceeding the lower limit of condition (13), the amount of distortion in the peripheral area becomes too large, which is undesirable for use as a wide-angle lens.If Vt becomes large by exceeding the upper limit of condition (13), the amount of distortion in the peripheral area becomes too large, which is undesirable for use as a wide-angle lens.

[0065] Conditional formula (14) prescribes half the diagonal length H of the rectangular image sensor IM and the focal length f1 of the first lens group. If f1 becomes smaller than the lower limit of conditional formula (14), the refractive power of the first lens group becomes too strong, increasing off-axis aberrations such as lateral chromatic aberration and making it difficult to obtain high optical performance. If f1 becomes larger than the upper limit of conditional formula (14), the negative refractive power of the first lens group becomes too weak, making it impossible to ensure a sufficient angle of view at the shortest focal length, which is undesirable.

[0066] In addition, when the length H of the rectangular image sensor IM is half the diagonal length of the image sensor, an image pickup apparatus having the zoom lens of the present invention has a 0.00 <D / H<2.28 ···(15) It is preferable that the following condition be satisfied:

[0067] Conditional formula (15) specifies the ratio of the distance D from a lens group including an aspherical lens having a negative aspherical amount closest to the image side, which is located closer to the image side than the first lens group, or a lens group having a negative refractive power, to the imaging plane, to the maximum image height Yt at the maximum focal length, i.e., half the diagonal length H of the rectangular image sensor IM. If D is smaller than the lower limit of conditional formula (15), the distance between the lens having a negative effect at the maximum focal length and the camera becomes too close, reducing the freedom of mechanical layout. If D is larger than the upper limit of conditional formula (15), the distance between the lens having a negative effect at the maximum focal length and the imaging plane becomes too large, making it difficult to correct distortion.

[0068] It is more preferable that the numerical ranges of the conditional expressions (2) to (15) be within the ranges of the following conditional expressions (2a) to (15a). -2.1 <f1 / fw<-0.5 ···(2a) -0.72 <f1 / ft<0.00 ···(3a) 1.2<(R1a+R1b) / (R1a-R1b)<4.0 (4a) 0.35 <skw / skt<1.00 ···(5a) 1.8 <ft / fw<3.7 ···(6a) 1.72 <G1Nd<2.30 ···(7a) 0.00 <D / H1<2.28 ···(8a) -0.0800 <Arl / Eal×Ndl<-0.0008 ···(9a) 0.0≦|Clw / Clt|<0.7 ···(10a) 82°<ωw<105° (11a) 1.4 <H / Yw<2.6 ···(12a) -twenty five% <Vt<25% ···(13a) -1.8 <H / f1<-0.6 ···(14a) 0.5 <D / H<2.0 ···(15a) It is more preferable that the numerical ranges of the conditional expressions (2) to (15) be within the ranges of the following conditional expressions (2b) to (15b). -2.1 <f1 / fw<-0.5 ···(2b) -0.6 <f1 / ft<0.0 ···(3b) 1.5<(R1a+R1b) / (R1a-R1b)<2.5 (4b) 0.60 <skw / skt<0.98 ···(5b) 2.0 <ft / fw<3.5 ···(6b) 1.9 <G1Nd<2.2 ···(7b) 0.8 <D / H1<1.8 ···(8b) -0.050 <Arl / Eal×Ndl<-0.001 ···(9b) 0.0≦|Clw / Clt|<0.5 (10b) 85°<ωw<100° (11b) 1.4 <H / Yw<2.6 ···(12b) -20% <Vt<20% ···(13b) -1.7 <H / f1<-0.7 ···(14b) 0.8 <D / H<1.8 ···(15b)

[0069] In the first to eighth embodiments, in order to realize a high-performance lens with a wide angle of view, it is desirable that the first lens group L1 is composed of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, a negative lens, and a positive lens. By arranging many negative lenses in the first lens group L1, it is possible to make the change in the height of off-axis rays gentler, and further by arranging a positive lens, it is possible to satisfactorily correct astigmatism.

[0070] In order to reduce distortion at the longest focal length and obtain an image with little distortion, it is desirable to have a lens group including an aspherical lens with a negative aspherical amount in the final group, or a lens group with negative refractive power. By shortening the distance between the imaging surface and the periphery, it is possible to effectively correct distortion at the longest focal length. In addition, at the shortest focal length of each embodiment, Y = 2f × sin(ω / 2) However, other projection methods specific to fisheye lenses as described above or other projection methods may also be used.

[0071] As described above, according to the present invention, a zoom lens having a wide imaging half angle of view of 80° or more at the shortest focal length, and capable of capturing images of subjects with a wide angle of view and little distortion at the longest focal length, is obtained, and the entire system is small in size and has high optical performance.

[0072] Numerical examples 1 to 8 corresponding to the first to eighth embodiments, respectively, are shown below. 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. Additionally, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. The Abbe number νd of a certain material is given by the following when 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 are Nd, NF, and NC, respectively: νd=(Nd-1) / (NF-NC) It is expressed as:

[0073] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values ​​when the zoom lens of each example is focused on an object at infinity. The back focus BF is the distance from the final lens surface to the image surface. The total lens length is the value obtained by adding the back focus to the distance from the first lens surface to the final lens surface.

[0074] If the optical surface is aspheric, a * symbol is added to the right of the surface number. The aspheric shape is expressed as follows, where X is the displacement from the apex of the surface in the optical axis direction, h is the height from the optical axis in a 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 aspheric coefficients of each order: x=(h 2 / R) / [1+{1-(1+k)(h / R) 2} 1 / 2 ]+A4×h4 +A6×h 6 +A8×h 8 +A10×h 10 +A12×h 12 In addition, "e±XX" in each aspheric coefficient is expressed as "×10 ±XX " It means.

[0075] [Example 1] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 68.891 2.70 1.75500 52.3 62.43 2 16.252 13.16 32.33 3* -31.358 1.80 1.85400 40.4 31.21 4* -295.709 7.22 27.91 5 -73.813 1.60 1.71999 50.2 27.71 6 107.450 0.20 27.78 7 31.028 6.60 1.85883 30.0 28.39 8 -92.576 1.40 1.55332 71.7 27.65 9 44.284 (variable) 25.54 10 23.175 3.90 1.58313 59.4 14.86 11 -25.709 0.80 1.69100 54.8 13.98 12 27.211 (variable) 14.05 13 38.274 2.90 1.78800 47.4 14.18 14 -22.489 0.80 1.71736 29.5 14.26 15 -290.445 0.20 14.34 16 18.736 2.04 1.49700 81.5 14.42 17 127.109 3.68 14.22 18(Aperture) ∞ 2.02 13.14 19 -576.349 1.50 1.69680 55.5 12.52 20 19.855 0.92 12.10 21 68.264 1.52 1.88300 40.8 12.13 22 -72.288 0.19 12.13 23 23.248 3.77 1.48749 70.2 11.94 24 -14.512 1.00 1.88300 40.8 12.51 25 57.926 1.24 13.98 26 54.769 2.84 1.59522 67.7 16.09 27 -28.633 (variable) 16.73 28* -23.977 1.20 1.58313 59.4 24.85 29 -49.364 (variable) 27.46 30* 31.365 5.47 1.55332 71.7 28.88 31* -39.338 (variable) 30.48 Image plane ∞ Aspheric Data 3rd page K = 0.00000e+000 A 2= 3.91548e-002 A 4=-1.15254e-004 A 6= 3.65395e-007 A 8=-3.36626e-010 A10=-3.45437e-013 Side 4 K = 0.00000e+000 A 2= 3.85729e-002 A 4=-1.25597e-004 A 6= 4.60400e-007 A 8=-6.08889e-010 A10= 2.45724e-012 A12=-9.48594e-015 Page 28 K = 0.00000e+000 A 2=-1.31706e-002 A 4= 9.31218e-005 A 6=-4.47912e-007 A 8= 2.32387e-009 A10=-5.66587e-012 A12= 3.97325e-015 Page 30 K = 0.00000e+000 A 2=-9.66503e-003 A 4=-5.30360e-005 A 6= 1.64954e-007 A 8=-8.89006e-010 A10= 9.44150e-013 Page 31 K = 0.00000e+000 A 2=-8.02162e-003 A 4= 4.70798e-005 A 6=-2.25802e-007 A 8= 7.67147e-010 A10=-3.05280e-012 A12= 4.61152e-015 Various data Zoom ratio 2.95 Wide-angle end Mid-range Telephoto end Focal length 8.13 14.00 24.00 F-number 4.12 4.12 4.15 Half angle of view 88.31 87.50 47.24 Image height 11.15 21.64 21.64 Lens length 123.86 114.76 116.93 BF 13.97 15.24 15.22 d 9 25.64 14.97 1.96 d12 8.95 0.56 0.56 d27 2.32 10.29 25.98 d29 2.31 3.01 2.54 d31 13.97 15.24 15.22 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -15.71 34.69 6.79 -18.67 2 10 -427.36 4.70 36.32 30.76 3 13 22.85 24.63 4.55 -17.30 4 28 -36.35 1.20 -0.32 -1.09 5 30 34.10 5.47 2.75 -0.83

[0076] [Example 2] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 68.066 2.70 1.76811 49.9 68.60 2 35.416 11.58 52.25 3 389.943 1.75 1.58425 69.1 48.22 4 17.721 11.45 31.50 5 -107.685 1.60 1.54748 73.9 30.92 6 29.245 5.49 28.53 7 32.841 2.84 1.91826 24.5 28.61 8 57.767 (variable) 28.04 9* 39.587 3.84 1.58313 59.4 16.23 10 -25.498 0.72 15.35 11 -23.025 0.98 1.77764 49.0 14.41 12 -49.203 (variable) 14.71 13 -141.956 1.70 1.80888 35.9 14.86 14 -57.206 0.09 15.00 15 32.149 3.99 1.52217 77.5 14.95 16 -33.521 0.17 14.53 17(Aperture) ∞ 1.27 14.01 18 -84.089 1.50 1.86122 39.2 13.47 19 25.216 1.02 12.93 20 189.489 0.96 1.71839 29.1 12.96 21 32.893 0.07 12.98 22 33.910 3.25 1.60119 67.4 12.99 23 -31.659 (variable) 13.09 24 124.769 5.90 1.64744 50.2 19.16 25 -18.299 1.00 1.88318 40.8 20.07 26 -45.025 (variable) 21.33 27 568.266 0.97 1.71290 53.3 26.29 28 33.943 2.99 27.15 29 43.003 6.23 1.49705 81.6 31.89 30 -154.751 (variable) 32.93 Image plane ∞ Aspheric Data 9th page K = 0.00000e+000 A 4=-2.22410e-005 A 6=-2.48822e-008 A 8=-7.54458e-011 A10= 3.77919e-012 A12=-3.86308e-014 Various data Zoom ratio 2.86 Wide-angle end Mid-range Telephoto end Focal length 8.41 15.30 24.01 F-number 4.12 4.12 4.12 Half angle of view 88.18 87.39 49.50 Image height 11.15 21.64 21.64 Lens length 133.43 120.78 124.90 BF 14.46 19.93 17.02 d 8 38.51 13.97 3.12 d12 3.22 2.55 1.20 d23 1.99 8.01 19.84 d26 1.18 2.27 9.65 d30 14.46 19.93 17.02 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -16.86 37.41 12.66 -19.86 2 9 50.28 5.54 0.44 -3.27 3 13 58.54 14.01 1.62 -8.54 4 24 84.22 6.90 2.95 -1.23 5 27 -249.93 10.19 -13.54 -22.38

[0077] [Example 3] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 97.221 2.50 2.00100 29.1 55.35 2 19.141 14.18 35.24 3 -103.708 1.80 1.99469 29.5 34.57 4 40.929 1.61 33.69 5 36.566 13.38 1.81603 25.3 35.63 6 -37.306 1.17 34.96 7 -31.839 1.40 1.53723 75.3 32.71 8 37.482 0.20 29.91 9 27.405 1.97 1.88592 22.7 29.89 10 34.208 (variable) 29.38 11 24.648 7.95 1.72245 38.5 26.18 12 -42.504 8.64 1.84730 23.8 24.57 13 18.139 1.59 17.32 14 23.971 6.99 1.99863 28.2 17.15 15 -79.895 2.81 1.60234 52.3 14.82 16 30.516 (variable) 14.48 17 (Aperture) ∞ 0.20 15.42 18 26.702 4.73 1.49684 81.6 15.77 19 -17.506 1.00 1.74329 49.0 15.69 20 -59.849 1.01 15.93 21 24.515 5.56 1.49691 81.6 15.88 22 -23.647 1.09 1.59740 56.6 15.68 23 22.897 (variable) 16.66 24 52.530 5.78 1.49692 81.6 18.67 25 -16.935 1.48 19.60 26 -16.582 1.20 1.77538 46.2 19.72 27 -26.924 0.10 21.22 28 170.564 2.18 1.49699 81.5 22.58 29 -242.516 1.00 23.02 30 -134.613 2.00 1.60000 55.0 23.32 31 287.552 (variable) 24.16 32* 25.506 4.09 1.58313 59.4 35.38 33 -57.987 (variable) 36.28 Image plane ∞ Aspheric Data Page 32 K = 0.00000e+000 A 2=-1.73275e-002 A 4=-2.04113e-005 A 6=-3.38575e-009 A 8=-1.92821e-011 A10=-2.78026e-015 Various data Zoom ratio 2.84 Wide-angle end Mid-range Telephoto end Focal length 8.44 14.82 24.00 F-number 4.12 4.12 4.15 Half angle of view 87.50 87.50 46.25 Image height 11.15 21.64 21.64 Lens length 162.00 153.46 162.75 BF 13.50 16.57 13.52 d10 37.62 8.92 1.00 d16 5.77 8.93 4.66 d23 5.88 2.62 1.35 d31 1.63 18.81 44.61 d33 13.50 16.57 13.52 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -15.84 38.21 5.03 -20.01 2 11 68.56 27.98 -14.92 -25.88 3 17 81.11 13.58 -13.10 -18.94 4 24 48.86 13.73 0.89 -8.80 5 32 79.10 4.09 2.06 -0.54

[0078] [Example 4] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 60.086 2.50 2.00100 29.1 58.00 2 18.346 15.93 35.22 3 -90.288 1.80 1.95523 32.0 33.82 4 48.533 1.90 31.82 5 33.425 8.44 1.80979 25.2 31.85 6 -60.948 1.66 30.71 7 -36.167 1.40 1.50887 79.6 30.07 8 23.876 0.20 26.10 9 22.554 2.20 1.89286 20.4 26.06 10 29.658 (variable) 25.45 11 18.800 5.14 1.91892 34.8 16.93 12 -30.140 0.80 1.91223 24.5 15.35 13 15.411 0.85 12.93 14 23.640 2.00 2.00070 25.5 12.75 15 -273.689 1.01 1.61748 54.3 12.14 16 24.551 (variable) 12.07 17 (Aperture) ∞ 0.20 13.45 18 24.172 4.45 1.49699 81.6 13.76 19 -14.119 1.00 1.98666 30.0 13.70 20 -1034.141 2.15 14.37 21 77.459 2.45 1.89840 24.3 15.60 22 -26.901 0.20 15.73 23 31.972 4.52 1.49700 81.6 16.75 24 -21.523 1.00 1.71597 37.0 16.88 25 32.554 (variable) 17.58 26 72.470 5.91 1.49700 81.6 20.74 27 -18.282 2.51 21.42 28 -16.179 1.20 1.80212 39.4 21.22 29 -31.272 (variable) 23.18 30* 58.138 2.50 1.58313 59.4 30.41 31 -33.285 (variable) 32.01 32 -255.425 1.50 1.87281 38.8 34.76 33 -129.647 (variable) 35.14 Image plane ∞ Aspheric Data Page 30 K = 0.00000e+000 A 2=-1.82032e-002 A 4=-2.30583e-005 A 6= 1.01076e-008 A 8=-9.21698e-011 A10= 5.35598e-014 Various data Zoom ratio 3.00 Wide-angle end Mid-range Telephoto end Focal length 8.00 14.03 24.00 F-number 4.12 4.12 4.15 Half angle of view 87.50 87.50 45.45 Image height 11.15 21.64 21.64 Lens length 132.04 126.91 135.41 BF 13.50 13.50 14.54 d10 32.81 12.32 1.00 d16 4.90 6.62 6.21 d25 4.70 4.44 1.15 d29 0.20 14.10 35.56 d31 0.50 0.50 1.52 d33 13.50 13.50 14.54 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -14.67 36.03 7.44 -15.60 2 11 62.44 9.79 -9.13 -12.97 3 17 46.30 15.97 0.74 -9.44 4 26 81.89 9.62 -1.66 -8.47 5 30 150.84 2.50 4.17 2.67 6 32 299.98 1.50 1.62 0.82

[0079] [Example 5] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 73.817 2.50 2.00100 29.1 58.00 2 19.350 16.18 36.22 3 -63.316 1.80 2.00107 29.1 35.00 4 84.477 0.19 34.14 5 54.287 8.66 1.81851 24.9 34.30 6 -42.087 1.21 33.76 7 -32.944 1.40 1.49697 81.6 33.40 8 36.431 0.20 30.41 9 33.666 2.40 1.89286 20.4 30.39 10 52.473 (variable) 29.92 11 16.051 2.71 1.71697 51.6 16.56 12 24.673 0.80 2.00073 25.5 15.28 13 14.808 0.93 14.20 14 22.439 2.88 1.90266 32.9 14.38 15 -41.685 1.00 1.69170 37.3 14.34 16 25.023 (variable) 14.11 17(Aperture) ∞ 0.20 15.37 18 25.455 5.05 1.49696 81.7 15.75 19 -15.894 1.00 1.91935 34.6 15.67 20 70.281 0.20 16.42 21 43.896 2.45 1.99304 25.4 16.77 22 -44.948 0.20 16.86 23 59.501 3.01 1.49706 81.6 16.61 24 -29.195 1.00 1.77474 32.5 16.36 25 96.007 (variable) 16.22 26 51.768 4.70 1.59678 67.6 21.11 27 -26.086 6.27 21.43 28 -16.955 1.20 1.93162 33.8 20.69 29 -33.742 (variable) 22.45 30* 26.873 2.50 1.58313 59.4 28.06 31 -210.742 (variable) 29.43 Image plane ∞ Aspheric Data Page 30 K = 0.00000e+000 A 2=-1.65940e-002 A 4=-2.57641e-005 A 6=-9.23106e-009 A 8=-1.24314e-010 A10= 9.47308e-014 Various data Zoom ratio 3.34 Wide-angle end Mid-range Telephoto end Focal length 8.39 14.42 28.00 F-number 4.12 4.12 4.15 Half angle of view 87.50 87.52 41.26 Image height 11.15 21.64 21.64 Lens length 143.29 127.48 127.37 BF 13.50 16.77 34.49 d10 42.79 17.46 1.00 d16 7.84 7.57 5.75 d25 8.33 6.36 0.20 d29 0.20 8.69 15.30 d31 13.50 16.77 34.49 Zoom lens group data Group Starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -17.42 34.54 5.58 -18.15 2 11 84.96 8.31 -9.49 -13.11 3 17 58.66 13.10 -0.61 -8.63 4 26 76.25 12.16 -11.33 -18.28 5 30 195.94 2.50 0.86 -0.73

[0080] [Example 6] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 56.152 2.50 2.00100 29.1 58.00 2 17.740 16.46 34.49 3 -80.185 1.80 1.85146 40.8 33.10 4 47.785 1.27 30.99 5 28.164 8.09 1.80673 25.4 30.78 6 -98.099 1.85 29.37 7 -39.529 1.40 1.54326 74.4 29.01 8 22.892 0.20 25.17 9 20.538 1.97 1.89286 20.4 25.12 10 25.157 (variable) 24.50 11 19.074 6.55 1.93576 33.4 17.02 12 -31.133 0.80 1.98504 25.3 14.34 13 16.098 0.81 12.36 14 26.052 2.00 2.00081 26.7 12.20 15 -437.637 3.76 1.51435 53.8 11.94 16 33.668 3.97 12.19 17(Aperture) ∞ 0.20 13.14 18 23.551 4.13 1.49700 81.6 13.48 19 -15.129 1.00 2.00094 28.3 13.45 20 -225.111 3.98 14.02 21 177.430 2.28 1.84666 23.8 17.11 22 -30.476 0.20 17.56 23 31.666 5.04 1.49700 81.6 19.16 24 -26.300 1.00 1.60843 42.6 19.38 25 28.540 1.00 20.17 26 41.088 6.71 1.49699 81.6 20.57 27 -18.011 1.20 21.22 28 -16.909 1.20 1.73756 49.5 21.02 29 -39.941 (variable) 22.71 30* 37.851 2.50 1.58313 59.4 30.96 31 -51.054 (variable) 32.44 Image plane ∞ Aspheric Data Page 30 K = 0.00000e+000 A 2=-1.72545e-002 A 4=-2.57001e-005 A 6= 1.11190e-008 A 8=-7.76257e-011 A10= 5.66353e-014 Various data Zoom ratio 3.00 Wide-angle end Mid-range Telephoto end Focal length 8.00 14.07 24.00 F-number 4.12 4.12 4.15 Half angle of view 87.50 87.50 45.29 Image height 11.15 21.64 21.64 Lens length 130.81 126.55 139.75 BF 13.91 13.50 13.50 d10 29.80 11.21 1.00 d29 3.22 17.95 41.37 d31 13.91 13.50 13.50 Zoom lens group data Group Starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -13.25 35.55 8.45 -13.21 2 11 28.61 45.83 15.61 -27.63 3 30 147.29 2.50 2.66 1.10

[0081] [Example 7] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 52.159 2.50 2.00101 29.1 43.52 2 14.228 11.13 26.83 3 -140.977 1.80 2.00091 27.9 25.93 4 31.950 0.19 24.46 5 23.651 6.84 1.98504 25.3 24.73 6 -71.666 1.37 23.58 7 -32.436 1.40 1.60479 66.1 23.23 8 19.120 0.20 20.33 9 18.594 2.35 1.89286 20.4 20.34 10 28.787 (variable) 19.72 11 15.238 4.92 1.92540 34.2 14.82 12 -19.878 0.80 1.93647 24.7 13.38 13 12.023 0.80 10.89 14 18.056 2.00 2.00071 25.5 11.15 15 -70.981 1.24 1.55661 45.8 11.14 16 19.572 (variable) 11.00 17 (Aperture) ∞ 0.20 11.59 18 17.301 4.97 1.49705 81.6 11.88 19 -10.521 1.00 1.95575 24.9 11.69 20 -54.004 1.00 12.27 21 485.066 2.78 1.84666 23.8 12.96 22 -14.951 0.20 13.59 23 -17.348 1.00 1.80582 37.2 13.68 24 74.533 1.96 1.49700 81.6 15.04 25 -50.508 (variable) 15.67 26 65.613 4.33 1.49700 81.6 18.09 27 -19.760 4.94 18.67 28 -13.346 1.20 1.79913 44.4 19.06 29 -20.937 (variable) 21.11 30* -99.594 2.50 1.58313 59.4 28.49 31 -22.223 (variable) 30.02 Image plane ∞ Aspheric Data Page 30 K = 0.00000e+000 A 2=-8.33890e-003 A 4=-4.56413e-005 A 6= 2.26227e-008 A 8=-1.58239e-010 A10=-1.64075e-013 Various data Zoom ratio 2.79 Wide-angle end Mid-range Telephoto end Focal length 8.60 14.84 24.00 F-number 4.12 4.12 4.15 Half angle of view 80.50 80.50 44.45 Image height 11.15 21.64 21.64 Lens length 100.03 101.73 111.69 BF 12.37 11.95 12.91 d10 19.62 7.42 1.00 d16 3.09 4.04 3.30 d25 1.12 1.67 0.20 d29 0.20 13.04 30.67 d31 12.37 11.95 12.91 Zoom lens group data Group Starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -12.61 27.78 5.69 -10.98 2 11 38.84 9.76 -5.68 -9.97 3 17 46.69 13.11 2.47 -6.70 4 26 67.46 10.48 -3.68 -11.45 5 30 88.45 2.50 3.67 2.18

[0082] [Example 8] Unit: mm Surface Data Surface number rd nd vd Effective diameter 1 69.380 2.50 2.00100 29.1 53.40 2 17.817 14.96 33.23 3 -54.823 1.80 2.00102 29.1 31.99 4 69.899 0.93 31.27 5 55.090 8.18 1.82494 24.6 31.60 6 -36.254 1.10 31.24 7 -29.119 1.40 1.50346 80.5 30.91 8 44.993 0.20 28.86 9 33.606 2.12 1.89286 20.4 28.81 10 50.362 (variable) 28.39 11 15.547 3.95 1.69839 53.5 16.26 12 29.187 0.80 1.97602 25.2 15.53 13 14.132 1.02 14.95 14 20.941 2.53 1.98390 30.2 15.16 15 -159.273 1.00 1.60928 39.1 15.09 16 21.748 (variable) 14.81 17 (Aperture) ∞ 0.20 16.40 18 24.308 5.58 1.49699 81.6 16.85 19 -16.733 1.00 1.95312 32.2 16.71 20 67.340 0.20 17.51 21 37.841 3.06 1.84665 23.8 18.01 22 -41.844 0.20 18.13 23 43.936 3.52 1.49701 81.6 17.82 24 -31.532 1.00 1.84883 34.6 17.49 25 83.522 (variable) 17.28 26 41.427 4.85 1.56501 71.5 20.86 27 -27.002 6.43 21.15 28 -17.250 1.20 1.86892 39.1 20.38 29 -45.703 (variable) 22.18 30* 28.332 2.50 1.58313 59.4 27.68 31 -44.408 (variable) 28.61 Image plane ∞ Aspheric Data Page 30 K = 0.00000e+000 A 2=-1.95525e-002 A 4=-2.47904e-005 A 6=-1.68825e-008 A 8=-6.79421e-011 A10=-6.48202e-014 Various data Zoom ratio 3.32 Wide-angle end Mid-range Telephoto end Focal length 8.43 14.71 28.00 F-number 4.12 4.12 4.15 Half angle of view 87.50 87.67 43.25 Image height 11.15 21.64 21.64 Lens length 145.00 131.05 136.47 BF 13.50 19.97 47.55 d10 43.04 18.68 1.00 d16 7.49 6.63 7.28 d25 8.55 4.93 0.20 d29 0.20 8.61 8.23 d31 13.50 19.97 47.55 Zoom lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 -16.14 33.19 4.86 -18.75 2 11 73.36 9.30 -9.65 -13.62 3 17 70.47 14.75 -3.12 -11.77 4 26 95.40 12.48 -19.46 -24.47 5 30 91.28 2.50 1.90 0.32

[0083] Various values ​​in each numerical example are summarized in Table 1 below. [Table 1]

[0084] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention as an imaging optical system will be described with reference to FIG. 19. In FIG. 19, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the zoom lenses described in the first to eighth embodiments. 12 denotes a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built into the camera body and receives an optical image formed by the imaging optical system 11 and photoelectrically converts it. 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. The imaging optical system 11 may be attached to the camera body 10, or the camera body 10 and the imaging optical system 11 may be an integrated type that cannot be detached. In this way, by applying the zoom lens of the present invention to an imaging device such as a digital still camera, it is possible to obtain an imaging device with a small lens.

[0085] 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]

[0086] L0 Zoom Lens L1 First lens group L2 2nd lens group (rear group) L3 3rd lens group (rear group) L4 4th lens group (rear group) L5 Fifth lens group (rear group) L6 6th lens group (rear group)

Claims

1. A zoom lens comprising a first lens group having negative refractive power and a rear group having four or more lens groups, which are arranged in this order from the object side to the image side, and in which the spacing between adjacent lens groups changes during zooming, the rear group includes a second lens group arranged closest to the object side in the rear group, and a third lens group having positive refractive power arranged adjacent to the second lens group on the image side, the rear group includes an aspheric lens having a negative aspheric amount; the positions of the lens groups arranged in the first lens group and the rear group can be set to a first zoom position, a second zoom position, and a third zoom position; the first zoom position is a wide-angle end position, the second zoom position is a zoom intermediate position, and the third zoom position is a telephoto end position, At each of the first and second zoom positions, the angle of view at the maximum image height is 160° or more; When the zoom lens is attached to a camera body having an image sensor, the first zoom position corresponds to a circular fisheye method, and the second zoom position corresponds to a diagonal fisheye method, Let Lw be the distance on the optical axis from the lens surface closest to the object of the zoom lens at the wide-angle end to the image surface, fw be the focal length of the zoom lens at the wide-angle end, Vt be the amount of distortion at the maximum image height at the telephoto end based on the central projection, Arl be the aspheric amount of the surface of the aspheric lens arranged closest to the image side among the aspheric lenses with the largest negative aspheric amount, Eal be the effective ray diameter, and Ndl be the refractive index. 5.0<Lw / fw<22.5 -30%<Vt<30% -0.1000<Arl / Eal×Ndl<-0.0003 A zoom lens characterized by satisfying the following conditional expressions:

2. When the focal length of the first lens group is f1, -2.1<f1 / fw<-0.5 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the focal length of the first lens group is f1 and the focal length of the zoom lens at the telephoto end is ft, -0.8<f1 / ft<0.0 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. The first lens group has a first negative lens having a negative refractive power closest to the object side, and the radii of curvature of the object-side and image-side lens surfaces of the first negative lens are R1a and R1b, respectively. 1.0<(R1a+R1b) / (R1a-R1b)<4.5 4. The zoom lens according to claim 1, which satisfies the following condition:

5. When the back focus at the wide-angle end is skw and the back focus at the telephoto end is skt, 0.31<skw / skt<1.20 5. The zoom lens according to claim 1, which satisfies the following condition:

6. When the focal length of the zoom lens at the telephoto end is ft, 1.5<ft / fw<4.0 6. The zoom lens according to claim 1, which satisfies the following condition:

7. The first lens group has a first negative lens having a negative refractive power closest to the object side, and the refractive index of the material of the first negative lens is G1Nd. 1.6<G1Nd<2.5 7. The zoom lens according to claim 1, which satisfies the following condition:

8. The rear group includes a lens group including an aspherical lens having a negative aspherical amount, or a lens group having a negative refractive power, the distance from the surface of the lens group closest to the image side to the image plane at the telephoto end is D, and the maximum image height is H1, 0.00<D / H1<2.28 8. The zoom lens according to claim 1, which satisfies the following condition:

9. 9. The zoom lens according to claim 1, wherein the first lens group is composed of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, a negative lens, and a positive lens.

10. 10. The zoom lens according to claim 1, wherein the lens group arranged closest to the image side is a lens group having negative refractive power or a lens group including at least one aspherical lens having a negative aspherical amount.

11. 11. The zoom lens according to claim 1, further comprising a storage unit for storing information relating to a correction amount of barrel distortion at the telephoto end.

12. 12. An imaging apparatus comprising: the zoom lens according to claim 1; and the imaging element for receiving an image formed by the zoom lens.

13. The imaging element has a rectangular imaging area, When the imaging half angle of view at the wide-angle end where the image height is defined by half the diagonal length of the imaging area is ωw, 80°<ωw<110° 13. The imaging apparatus according to claim 12, wherein the following condition is satisfied:

14. When half the diagonal length of the image sensor is H and the maximum image height at the wide-angle end is Yw, 1.4<H / Yw<2.6 14. The imaging apparatus according to claim 12, wherein the following condition is satisfied:

15. Let H be half the diagonal length of the image sensor and f1 be the focal length of the first lens group. -2.8<H / f1<-0.5 15. The image pickup apparatus according to claim 12, wherein the following condition is satisfied:

16. The rear group has a lens group including an aspherical lens having a negative aspherical amount, or a lens group having a negative refractive power, and the distance on the optical axis from the surface of the lens group that is closest to the image side among these lenses to the imaging plane is D, and half the diagonal length of the imaging element is H, 0.00<D / H<2.28 16. The imaging apparatus according to claim 12, wherein the following condition is satisfied:

Images