Zoom lens and imaging device having the same

Abstract

To provide a compact zoom lens that can obtain high optical performance while achieving a wide angle.SOLUTION: A zoom lens has a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, and a third lens group L3 having a positive refractive power, which are arranged in order from an object side to an image side, and consists of four or more lens groups. In zooming from a wide angle end to a telephoto end, the first lens group moves; the interval between the first lens group and the second lens group is increased; and the interval between the second lens group and the third lens group is decreased. The first lens group is formed of one positive lens, and the second lens group L2 includes three single lens elements continuously arranged in order from the object side to the image side and each having a negative refractive power. When SFY is the shape factor of a second single lens element that is adjacent to a first single lens element on the most object side among the three single lens elements while f1 is the focal distance of the first lens group and f2 is the focal distance of the second lens group, these satisfy a predetermined condition.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] Conventionally, in zoom lenses used in photo cameras, video cameras, and the like, a so-called rear focus system has been proposed in which focusing is performed by moving a lens group behind (on the image side of) a first lens group on the object side.

[0003] Furthermore, solid-state imaging devices such as CCD sensors and CMOS sensors in digital cameras and video cameras are becoming increasingly high-resolution. Also, photographic lenses are being required to have high optical performance, including chromatic aberration, while also becoming increasingly compact.

[0004] Patent Documents 1 and 2 disclose zoom lenses with a four-group configuration consisting of lens groups with positive, negative, positive, and positive refractive powers, in that order from the object side. In Patent Document 1, the first lens group is composed of one positive lens, and the second lens group is composed of four lenses, in that order from the object side: negative, negative, negative, and positive, thereby achieving a wider field of view and a fewer number of lenses. In Patent Document 2, the first lens group is composed of a cemented lens consisting of a negative lens and a positive lens, and the second lens group is composed of four lenses, in that order from the object side: negative, negative, negative, and positive, thereby achieving a wider angle of view and a fewer number of lenses. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-134747 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-035390 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a strong demand for lens systems used in image pickup devices that have high optical performance while being compact as a whole. To achieve good optical performance while miniaturizing the entire lens system, it is important to appropriately set the refractive power of each lens group and the movement conditions of each lens group associated with zooming. In particular, in cameras with large image sensors, when a wide angle is sought while ensuring a desired magnification, the front lens tends to become large, and therefore it is necessary to appropriately configure each lens group.

[0007] In Patent Document 1, high optical performance is ensured by ensuring a sufficient overall lens length in the telephoto range and suppressing the refractive power of each lens. However, if the image circle diameter is large, this undesirably leads to an increase in the size of the entire lens system.

[0008] In Patent Document 2, sufficient spacing is ensured between the second and third lens groups in the wide-angle range, and lateral chromatic aberration, field curvature, and distortion, which become issues as the angle of view becomes wider, are effectively corrected, but there are still issues with making the entire lens system smaller.

[0009] SUMMARY OF THE INVENTION An object of the present invention is to provide a compact zoom lens that achieves a wide angle while also providing high optical performance. [Means for solving the problem]

[0010] A zoom lens according to one aspect of the present invention comprises, arranged in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, 6 More than 1000 lenses During zooming, the spacing between adjacent lens groups changes.a zoom lens having a first lens group and a second lens group, the first lens group being configured with one positive lens, the second lens group being configured with three single lens elements, each having a negative refractive power, arranged successively from the object side to the image side in order, the first lens group being configured with one positive lens, the second lens group being configured with three single lens elements, each having a negative refractive power, arranged successively from the object side to the image side in order, the second single lens element being configured with three single lens elements and adjacent to the first single lens element closest to the object side, the second single lens element being configured with one positive lens, the first lens group being configured with one positive lens, the second single lens element being configured with three single lens elements and adjacent to the first single lens element closest to the object side in order, the second single lens element being configured with one positive lens, the first single lens element being configured with one positive lens, the second single lens element being configured with three single lens elements and each having a negative refractive power, the second single lens element being configured with three single lens elements and adjacent to the first single lens element closest to the object side in order, the first single lens element being configured with one positive lens, the second single lens element being configured with three single lens elements and each having a negative refractive power, the third single lens element being configured with one positive lens, the third single lens element being configured with one positive lens, the third single lens element being configured with three single lens elements and each having a negative refractive power, the third single lens element being configured with three single lens elements and each having a negative refractive power, the third single lens element being configured with three single lens elements and each having a negative refractive power, the third single lens element being configured with three single lens elements and each having a negative refractive power, the third single lens element being configured with three single lens elements and each having a negative refractive power, the fourth single lens element being configured with three single lens elements and each having a negative refractive power, the fourth single lens element being configured with three single lens elements and each having a negative refractive power, the fourth single lens element being configured with three single lens elements and each having a negative refractive power, the fourth single lens element being configured with three single lens elements and each having a negative refractive power, the fifth single lens element being configured with three single lens elements and each having a negative refractive power, the fifth 1.715 <SFY<10.0 -7.5 <f1 / f2<-0.5 The present invention is characterized in that the following conditions are satisfied:

[0011] According to another aspect of the present invention, there is provided a zoom lens comprising, arranged in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, 6 More than 1000 lenses During zooming, the spacing between adjacent lens groups changes. a zoom lens having a first lens group and a second lens group, the first lens group being configured with a single lens element having a positive refractive power, the second lens group being configured with three single lens elements, each having a negative refractive power, arranged successively from the object side to the image side, the first lens group being configured with a single lens element having a positive refractive power, the second lens group being configured with three single lens elements, each having a negative refractive power, arranged successively from the object side to the image side, the second lens group being configured with a single lens element having a shape factor of SFY, the first lens group being configured with a focal length of f1, the second lens group being configured with a focal length of f2, the third lens element being configured with a single lens element having a shape factor of fZ, the third lens element being configured with a shape factor of fZ, the first lens group being configured with a focal length of fZ, the second lens group being configured with a shape factor of fY, the second lens group being configured with a focal length of fZ, the third lens element being configured with a shape factor ... 1.715 <SFY<10.0 -7.5 <f1 / f2<-0.5 0.5 <fZ / f2<1.96 The present invention is characterized in that the following conditions are satisfied:

[0012] Other objects and features of the present invention will be described in the following embodiments. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a compact zoom lens that can achieve a wide angle while also achieving high optical performance. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are cross-sectional views of a zoom lens according to a first embodiment at a wide-angle end, a middle zoom position, and a telephoto end. [Figure 2] 1A and 1B are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. [Figure 3] 10A and 10B are cross-sectional views of a zoom lens according to a second embodiment at a wide-angle end, a middle zoom position, and a telephoto end. [Figure 4] 10A and 10B are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. [Figure 5] 10A and 10B are cross-sectional views of a zoom lens according to a third embodiment at a wide-angle end, at a middle zoom position, and at a telephoto end. [Figure 6] 10A and 10B are aberration diagrams of the zoom lens of Example 3 at the wide-angle end (A), at the intermediate zoom position (B), and at the telephoto end (C). [Figure 7] 10A and 10B are cross-sectional views of a zoom lens according to a fourth embodiment at a wide-angle end, at an intermediate zoom position, and at a telephoto end. [Figure 8] 10A and 10B are aberration diagrams of the zoom lens of Example 4 at the wide-angle end (A), at the intermediate zoom position (B), and at the telephoto end (C). [Figure 9] 10A and 10B are cross-sectional views of a zoom lens according to a fifth embodiment at a wide-angle end, at an intermediate zoom position, and at a telephoto end. [Figure 10] 10A and 10B are aberration diagrams of the zoom lens of Example 5 at the wide-angle end (A), at the intermediate zoom position (B), and at the telephoto end (C). [Figure 11] 10A and 10B are cross-sectional views of a zoom lens according to a sixth embodiment at a wide-angle end, at an intermediate zoom position, and at a telephoto end. [Figure 12]10A and 10B are aberration diagrams of the zoom lens of Example 6 at the wide-angle end (A), at the intermediate zoom position (B), and at the telephoto end (C). [Figure 13] FIG. 1 is a schematic diagram of an imaging device. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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.

[0016] FIG. 1 is a cross-sectional view of the zoom lens of Example 1 at the wide-angle end (short focal length end), at an intermediate zoom position, and at the telephoto end (long focal length end). FIGS. 2(A), 2(B), and 2(C) are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at an intermediate zoom position, and at the telephoto end, respectively. The aberration diagrams for each example are obtained when the zoom lens is focused on an object at infinity. The zoom lens of Example 1 has a zoom ratio of 2.9 and an aperture ratio of approximately 4.1 to 6.5.

[0017] Fig. 3 is a cross-sectional view of the zoom lens of Example 2 at the wide-angle end, at a middle zoom position, and at the telephoto end. Fig. 4(A), Fig. 4(B), and Fig. 4(C) are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at a middle zoom position, and at the telephoto end, respectively. The zoom lens of Example 2 is a zoom lens with a zoom ratio of 2.9 and an aperture ratio of approximately 4.1 to 6.5.

[0018] Fig. 5 is a cross-sectional view of the zoom lens of Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. Fig. 6(A), Fig. 6(B), and Fig. 6(C) are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively. The zoom lens of Example 3 is a zoom lens with a zoom ratio of 2.9 and an aperture ratio of approximately 4.1 to 6.5.

[0019] Fig. 7 is a cross-sectional view of the zoom lens of Example 4 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. Fig. 8(A), Fig. 8(B), and Fig. 8(C) are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively. The zoom lens of Example 4 is a zoom lens with a zoom ratio of 2.7 and an aperture ratio of approximately 4.1 to 6.0.

[0020] Fig. 9 is a cross-sectional view of the zoom lens of Example 5 at the wide-angle end, at the intermediate zoom position, and at the telephoto end. Fig. 10(A), Fig. 10(B), and Fig. 10(C) are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, at the intermediate zoom position, and at the telephoto end, respectively. The zoom lens of Example 5 is a zoom lens with a zoom ratio of 3.2 and an aperture ratio of approximately 4.1 to 6.5.

[0021] Fig. 11 is a cross-sectional view of the zoom lens of Example 6 at the wide-angle end, at a middle zoom position, and at the telephoto end. Fig. 12(A), Fig. 12(B), and Fig. 12(C) are aberration diagrams of the zoom lens of Example 6 at the wide-angle end, at a middle zoom position, and at the telephoto end, respectively. The zoom lens of Example 6 is a zoom lens with a zoom ratio of 2.9 and an aperture ratio of approximately 4.1 to 6.3.

[0022] The zoom lens of each embodiment is an imaging optical system used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, etc. The zoom lens of each embodiment can also be used as a projection optical system for a projection device (projector).

[0023] In each lens cross-sectional view, the left side is the object side (front) and the right side is the image side (rear). The zoom lens 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 spacing between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Note that a lens group may be composed of a single lens or multiple lenses. The lens group may also include an aperture stop.

[0024] In each lens cross-sectional view, if i is the order of the lens groups from the object side, Li indicates the ith lens group. SP is an aperture stop that determines (limits) the light beam at the maximum F-number (Fno). FP is a flare-cutting stop that cuts out unnecessary light. IP is the image plane, and when the zoom lens of each embodiment is used as the imaging optical system of a digital still camera or digital video camera, the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or CMOS sensor is located there. When the zoom lens of each embodiment is used as the imaging optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is located at the image plane IP. The focus arrow indicates the direction of movement of the lens groups when focusing from infinity to close range.

[0025] In the spherical aberration diagrams, Fno is the F-number and shows the amount of spherical aberration for the d-line (wavelength 587.56 nm) and g-line (wavelength 435.835 nm). In the astigmatism diagrams, 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 diagrams, the amount of distortion for the d-line is shown. In the chromatic aberration diagrams, the amount of chromatic aberration for the g-line is shown. ω is the imaging half angle of view (°), which is the angle of view determined by ray tracing. In the following examples, the wide-angle end and telephoto end refer to zoom positions when the variable magnification lens group is located at both ends of the range of mechanical movement along the optical axis.

[0026] Next, the characteristic configuration of the zoom lens of each embodiment will be described.

[0027] The zoom lens of each embodiment is a zoom lens consisting of four or more lens groups, arranged in order from the object side to the image side: a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, and a third lens group L3 with positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves, widening the gap between the first lens group L1 and the second lens group L2 and narrowing the gap between the second lens group L2 and the third lens group L3. The first lens group L1 is composed of one positive lens, and the second lens group L2 includes three single lens elements, each with negative refractive power, arranged consecutively from the object side to the image side. Furthermore, a rear group consisting of one or more lens groups is arranged on the image side of the third lens group L3.

[0028] Furthermore, the zoom lens of each embodiment satisfies the following conditional expressions (1) and (2).

[0029] 1.715 <SFY<10.0 ···(1) -7.5 <f1 / f2<-0.5 ···(2) Here, SFY is the shape factor of the single lens element Y (second single lens element) adjacent to the single lens element X (first single lens element) closest to the object among the three single lens elements arranged consecutively in the second lens group L2. f1 is the focal length of the first lens group L1. f2 is the focal length of the second lens group L2.

[0030] The zoom lens of each embodiment is configured to have first, second, and third lens groups with positive, negative, and positive refractive powers arranged in that order from the object side to the image side in order to shorten the overall lens length at the wide-angle end while effectively correcting aberrations throughout the entire zoom range. By configuring the lens with at least four groups, spherical aberration and coma occurring in the first lens group L1 and the second lens group L2 are effectively corrected. Furthermore, the zoom lens of each embodiment is a so-called positive-lead zoom type in which the first lens group L1 has positive refractive power, and the height of incidence of axial rays on each lens element located closer to the image than the second lens group L2 is reduced, thereby achieving a radially compact zoom lens.

[0031] Furthermore, in order to ensure compactness and a high zoom ratio, zooming is performed by changing the spacing between each lens group so that the spacing between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, and the spacing between the second lens group L2 and the third lens group L3 is narrower.

[0032] The first lens group L1 is composed of one positive lens. This configuration reduces the number of lenses in the first lens group L1, which has a large lens diameter, making it possible to achieve a smaller and lighter lens. In addition, the height of light rays emerging from the first lens group L1 can be reduced, enabling effective correction of various aberrations such as spherical aberration and coma.

[0033] The second lens group L2 is configured to include three single lens elements, each with negative refractive power, arranged consecutively from the object side to the image side. Here, in the case of a composite optical element (also called a hybrid aspherical surface or a replica aspherical surface) such as a replica resin layer, the single lens element includes the resin layer. Specifically, for example, in the numerical data of Example 4 described below, the single lens element includes a resin layer with an on-axis thickness of 0.3 mm or less (0.15 mm in Example 4) formed on the object side of the third lens element. Furthermore, when specifying materials, the resin layer is not taken into consideration in the calculation. This configuration of the second lens group L2 enhances the refractive power of the second lens group L2 while correcting the curvature of field and chromatic aberration of magnification that occur in the second lens group L2 in the wide-angle range and the spherical aberration in the telephoto range. This prevents the front lens from becoming too large, which is a problem when widening the angle of view. By arranging a negative lens closest to the object side in the second lens unit L2, the power arrangement within the second lens unit L2 can be made retrofocus type, and curvature of field and coma in the wide-angle range are effectively corrected.

[0034] Conditional expression (1) defines the shape factor of single lens element Y adjacent to single lens element X closest to the object among the three consecutively arranged single lens elements with negative refractive power in second lens unit L2, and is intended to effectively correct curvature of field and lateral chromatic aberration in the wide-angle range. Here, the shape factor SF of the lens elements is defined by the following equation, where R1 is the radius of curvature of the lens surface closest to the object, and R2 is the radius of curvature of the lens surface closest to the image.

[0035] SF=sgn(f)(R2+R1) / (R2-R1) If the lens element has an aspherical shape, it means its base R (the radius of the reference quadratic curve). If the lens element includes a composite optical element such as a replica resin layer, it is calculated using the radius of curvature of that resin layer. sgn is a sign function, and f is the focal length of the lens element. In other words, the sign of the sign function is "+" for a positive lens and "-" for a negative lens.

[0036] If the upper limit of conditional expression (1) is exceeded, the negative single lens element Y will have a meniscus shape with a strong convexity on the object side, making it difficult to effectively correct lateral chromatic aberration in the wide-angle range. Furthermore, when securing a desired angle of view at the wide-angle end, the overall lens length will increase, which is undesirable. If the lower limit of conditional expression (1) is exceeded, the radius of curvature on the object side will increase, which is undesirable because it will increase curvature of field and astigmatic difference in the wide-angle range.

[0037] Conditional expression (2) defines the focal length f1 of the first lens group L1 in terms of the focal length f2 of the second lens group L2, and is intended to maintain an appropriate zoom ratio and reduce the size of the entire zoom lens system. To achieve a wide angle of view while maintaining a predetermined magnification, the refractive power distribution between the first lens group L1 and the second lens group L2 must be appropriately set. Furthermore, to effectively correct spherical aberration in the telephoto range, the refractive power of the first lens group L1 must be appropriately maintained within a range that allows for aberration correction. Exceeding the upper limit of conditional expression (2) increases the refractive power of the first lens group L1, which is advantageous for achieving a compact size but disadvantageous for achieving a wide angle of view and makes it difficult to correct curvature of field in the wide-angle range. Falling below the lower limit of conditional expression (2), the refractive power of the first lens group L1 decreases, increasing the overall length of the entire zoom lens system and making it difficult to maintain adequate peripheral illumination, which is undesirable.

[0038] Furthermore, it is preferable that the numerical ranges of the conditional expressions (1) and (2) satisfy the ranges of the following conditional expressions (1a) and (2a).

[0039] 1.715 <SFY<5.0 ···(1a) -7.3 <f1 / f2<-2.0 ···(2a) By satisfying conditional expression (1a), it is possible to suppress the astigmatic difference in the wide-angle range and to easily suppress the variation in lateral chromatic aberration for each wavelength.Furthermore, by satisfying conditional expression (2a), it is possible to suppress coma in the telephoto range and to shorten the overall lens length, which is preferable.

[0040] It is more preferable that the numerical ranges of the conditional expressions (1) and (2) be within the ranges of the following conditional expressions (1b) and (2b).

[0041] 1.715 <SFY<3.0 ···(1b) -7.2 <f1 / f2<-4.3 ···(2b) As described above, by appropriately configuring each lens group and simultaneously satisfying conditional expressions (1) and (2), it is possible to achieve a compact zoom lens that satisfies various aberrations such as spherical aberration, coma, and curvature of field, and that covers an ultra-wide-angle range in which the half angle of view at the wide-angle end exceeds 45 degrees.

[0042] The zoom lens of each embodiment can also adopt the following configuration as an alternative.

[0043] As another example, the zoom lens of each embodiment is a zoom lens consisting of four or more lens groups, arranged in order from the object side to the image side: a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, and a third lens group L3 with positive refractive power. When zooming from the wide-angle end to the telephoto end, the first lens group L1 moves, widening the gap between the first lens group L1 and the second lens group L2 and narrowing the gap between the second lens group L2 and the third lens group L3. The first lens group L1 is composed of a single lens element with positive refractive power, and the second lens group L2 has three single lens elements, each with negative refractive power, arranged consecutively from the object side to the image side. A rear group consisting of one or more lens groups is located on the image side of the third lens group L3.

[0044] Furthermore, as another means, the zoom lens of each embodiment satisfies the following conditional expressions (1), (2), and (3).

[0045] 1.715 <SFY<10.0 ···(1) -7.5 <f1 / f2<-0.5 ···(2) 0.5 <fZ / f2<1.96 ···(3) Here, SFY, f1, and f2 are as described above, and fZ is the focal length of the single lens element Z (third single lens element) closest to the image side among the three single lens elements with negative refractive power arranged consecutively in the second lens group L2.

[0046] It should be noted that the description of the above zoom lens configuration and conditions that overlap with the configuration and conditions of the zoom lens described above will be omitted.

[0047] The first lens group L1 is composed of a single-element lens with positive refractive power. Here, a single-element lens refers to a single lens or a cemented lens formed by cementing together multiple lenses. This configuration reduces the axial thickness of the first lens group L1, which has a large lens diameter, and prevents the front lens diameter from becoming too large, which is a problem in zoom lenses with ultra-wide-angle lenses. Furthermore, the height of light rays emerging from the first lens group L1 can be reduced, enabling effective correction of various aberrations, such as spherical aberration and coma.

[0048] Conditional expression (3) defines the focal length of the single lens element Z, which is closest to the image among the three consecutively arranged single lens elements with negative refractive power in the second lens unit L2, as the focal length f2 of the second lens unit L2. This is intended to provide good correction for lateral chromatic aberration in the wide-angle range and to achieve compactness. If the upper limit of conditional expression (3) is exceeded, the refractive power contribution of the single lens element Z relative to the refractive power of the second lens unit L2 becomes small, and the refractive power contributions of the single lens elements X and Z increase, making it difficult to correct curvature of field in the wide-angle range. If the lower limit of conditional expression (3) is exceeded, the refractive power contribution of the single lens element Z relative to the refractive power of the second lens unit L2 becomes large, which is advantageous for correcting lateral chromatic aberration but undesirably results in an increase in the diameter of the front lens.

[0049] Furthermore, it is preferable that the numerical ranges of the conditional expressions (1), (2), and (3) satisfy the ranges of the following conditional expressions (1a), (2a), and (3a).

[0050] 1.715 <SFY<5.0 ···(1a) -7.3 <f1 / f2<-2.0 ···(2a) 1.0 <fZ / f2<1.956 ···(3a) By satisfying conditional formula (1a), it is easy to suppress the variation in lateral chromatic aberration for each wavelength while suppressing astigmatic difference in the wide-angle range. By satisfying conditional formula (2a), it is possible to reduce the overall lens length while suppressing coma aberration in the telephoto range, which is preferable. Furthermore, by satisfying conditional formula (3a), it is possible to reduce the overall lens length while suppressing variation in spherical aberration for each wavelength in the telephoto range, which is preferable.

[0051] It is more preferable that the numerical ranges of the conditional expressions (1), (2), and (3) be within the ranges of the following conditional expressions (1b), (2b), and (3b).

[0052] 1.715 <SFY<3.0 ···(1b) -7.2 <f1 / f2<-4.3 ···(2b) 1.2 <fZ / f2<1.952 ···(3b) As described above, by appropriately configuring each lens group and simultaneously satisfying conditional expressions (1), (2), and (3), it is possible to achieve a compact zoom lens that satisfies various aberrations such as spherical aberration, coma, and curvature of field, and that covers an ultra-wide-angle range in which the half angle of view at the wide-angle end exceeds 45 degrees.

[0053] Next, conditions that are preferably satisfied in the zoom lens of each embodiment will be described: It is preferable that the zoom lens of each embodiment satisfy one or more of the following conditional expressions (4) to (12).

[0054] 1.0 <SFX<3.0 ···(4) 0.6 <SF1<3.0 ···(5) 1.19 <nX / nZ<1.31 ···(6) 0.35 <fX / fY<1.50 ···(7) 0.70 <fX / f2<2.20 ···(8) 0.90 <skw / fw<1.45 ···(9) 5.1 <f1 / fw<14.0 ···(10) 0.38 <f3 / ft<2.00 ···(11) 0.3 <V<1.0 ···(12) Here, SFX is the shape factor of single lens element X. SF1 is the shape factor of one positive lens in the first lens group L1 or one lens element with positive refractive power in the first lens group L1. nX and nZ are the refractive indices at the d-line of single lens elements X and Z, respectively. fX and fY are the focal lengths of single lens elements X and Y in the second lens group L2, respectively. skw is the back focus of the zoom lens at the wide-angle end. fw is the focal length of the zoom lens at the wide-angle end. f3 is the focal length of the third lens group L3. ft is the focal length of the zoom lens at the telephoto end. V is the third-order aberration coefficient of distortion at the wide-angle end.

[0055] Conditional expression (4) defines the shape factor of the single lens element X, and is intended to achieve compactness while suppressing curvature of field and astigmatic difference in the wide-angle range. When the value of conditional expression (4) is 1, the single lens element X has a plano-concave shape with a concave surface on the image side. If the upper limit of conditional expression (4) is exceeded, it becomes difficult to satisfactorily correct curvature of field and astigmatism on the wide-angle side, and zoom fluctuations in curvature of field become large, which is undesirable. If the lower limit of conditional expression (4) is exceeded, angle-of-view fluctuations in chromatic aberration of magnification on the wide-angle side become large, which is undesirable.

[0056] Conditional formula (5) defines the shape factor of a single positive lens in the first lens unit L1 or a single lens element with positive refractive power in the first lens unit L1. The first lens unit L1 is configured to have a strongly convex surface facing the object side, thereby effectively correcting spherical aberration and coma at the telephoto end. By configuring the first lens unit L1 to have a strongly convex surface facing the object side, the angles of incidence and refraction of off-axial light rays entering from the object side can be reduced, thereby suppressing astigmatism throughout the entire zoom range. Exceeding the upper limit of conditional formula (5) makes the meniscus shape of the first lens unit L1 too strong, making it difficult to correct spherical aberration and coma at the telephoto end. Falling below the lower limit of conditional formula (5) undesirably increases the curvature of field and astigmatic difference at the wide-angle end.

[0057] Conditional formula (6) defines the ratio of the refractive indices nX and nZ at the d-line of the single lens elements X and Z, and is intended to minimize the overall lens system size while ensuring high imaging performance at wide angles. Due to the characteristics of glass, as the refractive index increases, the Abbe number decreases, which tends to result in insufficient correction of chromatic aberration. Therefore, to suppress chromatic aberration to a desired level, the refractive power must be weakened, resulting in an increase in the overall lens length. Furthermore, in retrofocus lenses, reducing the number of lens elements to achieve compactness tends to result in a negative Petzval sum, tilting the image plane to the over-angle side and increasing the astigmatic difference. Therefore, it is important to optimize the refractive index of the negative lens element to effectively correct curvature of field and astigmatic difference. Exceeding the upper limit of conditional formula (6) is advantageous for image plane correction, but makes it difficult to correct lateral chromatic aberration. If the lower limit of conditional expression (6) is exceeded, it is advantageous for suppressing lateral chromatic aberration in the wide-angle range, but it is disadvantageous for widening the angle of view and leads to an increase in the diameter of the front lens element, which is not desirable.

[0058] Conditional expression (7) defines the ratio of the focal lengths of the single lens element X and the single lens element Y, and is intended to optimize the distribution of refractive power within the second lens unit L2 and achieve compactness while suppressing curvature of field and astigmatic difference. If the upper limit of conditional expression (7) is exceeded, the refractive power of the single lens element X becomes weak, resulting in an increase in the diameter of the front lens. If the lower limit of conditional expression (7) is exceeded, the refractive power of the single lens element X becomes strong, which is advantageous for compactness but makes it difficult to correct curvature of field and astigmatism.

[0059] Conditional expression (8) defines the focal length of the single lens element X in terms of the focal length f2 of the second lens unit L2, and is intended to suppress curvature of field in the wide-angle range and coma in the telephoto range. If the upper limit of conditional expression (8) is exceeded, the refractive power contribution of the single lens element X relative to the refractive power of the second lens unit L2 becomes small, and the refractive power contribution of the single lens element Y increases, making it difficult to correct curvature of field in the wide-angle range. If the lower limit of conditional expression (8) is exceeded, the refractive power contribution of the single lens element X relative to the refractive power of the second lens unit L2 becomes large, which is undesirable because it increases the variation in coma with each image height from the intermediate zoom range to the telephoto range.

[0060] Conditional expression (9) defines the back focal length skw at the wide-angle end in terms of the focal length fw at the wide-angle end, and defines the so-called retro ratio. If the lower limit of conditional expression (9) is not met, the back focal length becomes short, making it difficult to arrange the shutter components, etc. If the upper limit of conditional expression (9) is exceeded, the back focal length becomes long, making it difficult to correct the curvature of field in the wide-angle range and requiring an increase in the number of lens elements, which is undesirable.

[0061] Conditional expression (10) defines the focal length f1 of the first lens unit L1 as the focal length fw at the wide-angle end, optimizing the magnification sharing while achieving compactness. By setting the desired refractive power for the first lens unit L1, the amount of movement of the first lens unit L1 during zooming can be reduced. Exceeding the upper limit of conditional expression (10) weakens the refractive power of the first lens unit L1, weakening the magnification sharing effect. Therefore, increasing the amount of movement of the first lens unit L1 during zooming to compensate for the magnification sharing effect would undesirably increase the overall length at the telephoto end. Furthermore, the third lens unit L3 and subsequent lens units must share the magnification sharing, which would result in significant spherical aberration, coma, and other aberrations occurring at the telephoto end. This increases the number of lens elements and aspherical lenses required for aberration correction, which tends to reduce robustness to manufacturing errors. If the refractive power of the first lens unit L1 is too strong and falls below the lower limit of conditional expression (10), a large amount of spherical aberration occurs from the first lens unit L1 on the telephoto side, which is undesirable.

[0062] Conditional expression (11) defines the focal length f3 of the third lens unit L3 in terms of the focal length ft at the telephoto end, and is intended to ensure a sufficient share of magnification changes while favorably correcting spherical aberration and coma. Exceeding the upper limit of conditional expression (11) is undesirable because the refractive power of the third lens unit L3 becomes weak, weakening the magnification change function and increasing the amount of movement of the third lens unit L3 during zooming. Falling below the lower limit of conditional expression (11) is undesirable because the refractive power of the third lens unit L3 becomes too strong, resulting in spherical aberration, coma aberration on the telephoto side, and astigmatic difference at the center of the image field.

[0063] Conditional expression (12) defines the third-order aberration coefficient of distortion at the wide-angle end, and is intended to appropriately correct curvature of field and astigmatism, and to suppress degradation of resolution due to enlargement when electronic distortion correction is performed. Exceeding the upper limit of conditional expression (12) increases distortion, which is advantageous for compactness, but undesirably increases degradation of resolution due to enlargement. Falling below the lower limit of conditional expression (12) makes it difficult to effectively correct curvature of field and lateral chromatic aberration, undesirably.

[0064] It is more preferable that the numerical ranges of the conditional expressions (4) to (12) be within the ranges of the following conditional expressions (4a) to (12a).

[0065] 1.1 <SFX<2.0 ···(4a) 0.8 <SF1<2.4 ···(5a) 1.21 <nX / nZ<1.29 ···(6a) 0.40 <fX / fY<1.30 ···(7a) 0.75 <fX / f2<2.00 ···(8a) 0.92 <skw / fw<1.40 ···(9a) 5.3 <f1 / fw<12.0 ···(10a) 0.40 <f3 / ft<1.90 ···(11a) 0.33 <V<0.60 ···(12a) By satisfying conditional expression (4a), correction of curvature of field at wide-angle ranges becomes more appropriate, making it easier to correct curvature of field even when the angle of view is increased. By satisfying conditional expression (5a), correction of spherical aberration and coma at telephoto ranges becomes easier. By satisfying conditional expression (6a), variation in lateral chromatic aberration due to zooming becomes easier to suppress. By satisfying conditional expression (7a), zoom variation in curvature of field becomes easier to suppress. By satisfying conditional expression (8a), coma at telephoto ranges, particularly variation for each wavelength, becomes easier to suppress. By satisfying conditional expression (9a), the overall lens length and the diameters of the front and rear lenses at the wide-angle end become appropriate, making it easier to achieve a compact overall lens system. By satisfying conditional expression (10a), correction of lateral chromatic aberration at the wide-angle end and spherical aberration at the telephoto end become easier to correct simultaneously. By satisfying conditional expression (11a), the magnification variation share of the third lens group is optimized, making it easier to suppress fluctuations in coma during zooming.By satisfying conditional expression (12a), it becomes easier to achieve both a small front lens diameter and sufficient resolution at the peripheral angles of view.

[0066] It is more preferable that the numerical ranges of the conditional expressions (4) to (12) be within the ranges of the following conditional expressions (4b) to (12b).

[0067] 1.2 <SFX<1.7 ···(4b) 1.0 <SF1<2.1 ···(5b) 1.23 <nX / nZ<1.27 ···(6b) 0.44 <fX / fY<1.11 ···(7b) 0.85 <fX / f2<1.78 ···(8b) 0.94 <skw / fw<1.35 ···(9b) 5.5 <f1 / fw<10.0 ···(10b) 0.42 <f3 / ft<1.86 ···(11b) 0.36 <V<0.51 ···(12b) Next, the configurations that are preferably satisfied in the zoom lens of each embodiment will be described.

[0068] The first lens unit L1 is preferably composed of a positive single lens or a cemented lens consisting of a negative lens and a positive lens, which makes it easy to effectively correct lateral chromatic aberration throughout the entire zoom range, as well as spherical aberration and axial chromatic aberration on the telephoto side.

[0069] The second lens group L2 preferably consists of three negative single lens elements and one positive single lens element. By limiting the number of positive single lens elements to one, achromatism within the second lens group can be achieved while also achieving compactness.

[0070] The relative position of the second lens unit L2 with respect to the image plane position is preferably closer to the object at the telephoto end than at the wide-angle end, which allows the entrance pupil to be positioned closer to the object at wide-angle ranges, suppresses the increase in the front lens diameter that accompanies widening the angle of view, and makes it easier to effectively correct fluctuations in field curvature due to zooming.

[0071] The third lens group L3 preferably has a single lens with positive refractive power and convex toward the object side, located closest to the object. The ray height of the light beam entering the third lens group L3 from the second lens group L2 for the main magnification is high, which causes high-order spherical aberration and coma. Therefore, to effectively suppress the occurrence of spherical aberration and coma, a single lens with positive refractive power and convex toward the object side is located closest to the object side of the third lens group L3. This makes it easier to ensure the positive refractive power required to converge the light beam diverged by the second lens group L2.

[0072] It is preferable that the aperture stop SP be located within the third lens unit L3. In order to ensure the desired magnification and reduce the size of the entire system, it is important to minimize the distance between the second lens unit L2 and the third lens unit L3 at the telephoto end. This configuration makes it easy to achieve this.

[0073] In the lens group closest to the image, it is preferable that the lens closest to the image is a positive lens that is convex toward the image side, which makes it relatively easy to ensure back focus and also makes it possible to suppress the collection of unwanted light (ghosts) caused by the image sensor.

[0074] Furthermore, in order to effectively correct curvature of field at the wide-angle end while also achieving compactness, it is preferable that the rear group have at least one aspherical surface.

[0075] Next, the zoom lens of each embodiment will be described in detail.

[0076] In Example 1 of Figure 1, L1 is a first lens group with a positive refractive power, L2 is a second lens group with a negative refractive power, L3 is a third lens group with a positive refractive power, L4 is a fourth lens group with a negative refractive power, L5 is a fifth lens group with a positive refractive power, and L6 is a sixth lens group with a positive refractive power. In the zoom lens of Example 1, the first lens group L1 moves monotonically toward the object side during zooming from the wide-angle end to the telephoto end. Each lens group moves so that the distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, and the distance between the second lens group L2 and the third lens group L3 is narrower. During focusing, the fourth lens group L4 moves.

[0077] In Example 2 shown in Figure 3, L1 is the first lens group with a positive potential, L2 is the second lens group with a negative potential, L3 is the third lens group with a positive potential, L4 is the fourth lens group with a positive potential, L5 is the fifth lens group with a negative potential, L6 is the sixth lens group with a positive potential, and L7 is the seventh lens group with a positive potential. In the zoom lens of Example 2, the first lens group L1 moves monotonically toward the object side during zooming from the wide-angle end to the telephoto end. The lens groups move so that, at the telephoto end compared to the wide-angle end, the distance between the first lens group L1 and the second lens group L2 is wider, the distance between the second lens group L2 and the third lens group L3 is narrower, and the distance between the third lens group L3 and the fourth lens group L4 is wider. The fifth lens group L5 moves during focusing.

[0078] In Example 3 shown in Figure 5, L1 is the positive first lens group, L2 is the negative second lens group, L3 is the positive third lens group, L4 is the negative fourth lens group, L5 is the positive fifth lens group, L6 is the negative sixth lens group, L7 is the positive seventh lens group, and L8 is the positive eighth lens group. In the zoom lens of Example 3, the first lens group L1 moves monotonically toward the object side during zooming from the wide-angle end to the telephoto end. The lens groups move so that the distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, and the distance between the second lens group L2 and the third lens group L3 is wider. The sixth lens group L6 moves during focusing.

[0079] In Example 4 shown in Figure 7, L1 is the first positive lens group, L2 is the second negative lens group, L3 is the third positive lens group, L4 is the fourth positive lens group, L5 is the fifth negative lens group, L6 is the sixth negative lens group, and L7 is the seventh positive lens group. In the zoom lens of Example 4, the first lens group L1 moves monotonically toward the object side during zooming from the wide-angle end to the telephoto end. The lens groups move so that the distance between the first lens group L1 and the second lens group L2 is wider at the telephoto end than at the wide-angle end, the distance between the second lens group L2 and the third lens group L3 is narrower, and the distance between the third lens group L3 and the fourth lens group L4 is narrower. During focusing, the fifth lens group L5 moves.

[0080] In Examples 5 and 6 shown in Figures 9 and 11, L1 is the positive first lens group, L2 is the negative second lens group, L3 is the positive third lens group, L4 is the negative fourth lens group, L5 is the negative fifth lens group, and L6 is the positive sixth lens group. In the zoom lenses of Examples 5 and 6, the first lens group L1 moves monotonically toward the object side during zooming from the wide-angle end to the telephoto end. The lens groups move so that, at the telephoto end, the distance between the first lens group L1 and the second lens group L2 is wider, the distance between the second lens group L2 and the third lens group L3 is narrower, and the distance between the third lens group L3 and the fourth lens group L4 is narrower than at the wide-angle end. During focusing, the fourth lens group L4 moves.

[0081] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below.

[0082] 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. Also, 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 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:

[0083] 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. "Back focus BF" 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.

[0084] 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.

[0085] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 65.219 4.71 1.62299 58.1 2 282.412 (variable) 3 140.410 1.50 1.87070 40.7 4 17.508 4.66 5 43.349 1.30 1.77250 49.6 6 20.537 6.65 7 -37.386 1.20 1.49700 81.6 8 53.630 0.25 9 35.855 5.36 1.91082 35.3 10 -78.718 (variable) 11 -196.351 2.90 1.59282 68.6 12 -46.465 2.94 13 (Aperture) ∞ 0.99 14 32.882 3.59 1.55032 75.5 15 -17.323 1.00 1.80420 46.5 16 -61.956 3.37 17 28.359 1.00 1.87070 40.7 18 13.927 6.28 1.59410 60.5 19 -42.827 (variable) 20 31.004 1.20 1.87070 40.7 21 15.532 (variable) 22* -48.387 2.50 1.53110 55.9 23* -48.784 (variable) 24 -64.185 4.54 1.51742 52.2 25 -34.142 (variable) Image plane ∞ Aspheric data Page 22 K = 0.00000e+000 A 4= 1.70820e-005 A 6= 1.17704e-006 A 8=-1.93813e-008 A10= 1.18524e-010 Page 23 K = 0.00000e+000 A 4= 2.23932e-005 A 6= 7.39253e-007 A 8=-9.96858e-009 A10= 4.35328e-011 Various data Zoom ratio 2.87 Wide-angle Mid-range Telephoto Focal length 18.50 32.06 53.01 F-number 4.11 5.27 6.48 Half angle of view (°) 49.17 34.18 22.02 Image height 18.50 21.64 21.64 Lens length 117.88 125.56 150.43 BF 19.52 17.08 24.90 d 2 0.63 10.40 25.55 d10 27.81 11.33 1.63 d19 3.73 2.78 1.22 d21 4.59 5.54 7.10 d23 5.64 22.49 34.09 d25 19.52 17.08 24.90 Zoom lens group data Group starting plane focal length 1 1 135.00 2 3 -25.86 3 11 23.31 4 20 -37.08 5 22 9467.08 6 24 134.06 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 57.137 5.05 1.62041 60.3 2 181.038 (variable) 3 92.646 1.50 1.87070 40.7 4 18.435 5.04 5 53.487 1.30 1.77250 49.6 6 20.012 7.39 7 -38.576 1.20 1.49700 81.6 8 66.841 0.25 9 38.597 5.51 1.91082 35.3 10 -90.457 (variable) 11 135.230 2.47 1.59282 68.6 12 -104.831 (variable) 13 (Aperture) ∞ 1.17 14 22.495 1.00 1.75500 52.3 15 14.326 4.05 1.55032 75.5 16 -136.741 0.97 17 37.075 3.53 1.59282 68.6 18 -17.869 1.00 1.88300 40.8 19 -62.442 (variable) 20 40.861 1.20 1.87070 40.7 21 16.342 (variable) 22* -22.506 2.50 1.53110 55.9 23* -17.759 (variable) 24 -74.828 4.73 1.49700 81.6 25 -36.656 (variable) Image plane ∞ Aspheric data Page 22 K = 0.00000e+000 A 4= 5.20682e-005 A 6= 5.88541e-007 A 8= 4.66887e-009 A10=-5.97942e-011 Page 23 K = 0.00000e+000 A 4= 4.72873e-005 A 6= 3.63857e-007 A 8= 4.30450e-009 A10=-3.23834e-011 Various data Zoom ratio 2.92 Wide-angle Mid-range Telephoto Focal length 18.50 31.67 54.02 F-number 4.12 5.26 6.48 Half angle of view (°) 48.65 34.97 21.91 Image height 18.50 21.64 21.64 Lens length 121.60 129.93 156.78 BF 23.41 19.49 29.34 d 2 0.69 9.30 24.76 d10 29.53 12.55 0.36 d12 3.66 4.49 5.66 d19 2.96 2.20 0.84 d21 4.64 5.41 6.76 d23 6.84 26.62 39.18 d25 23.41 19.49 29.34 Zoom lens group data Group starting plane focal length 1 1 132.50 2 3 -25.23 3 11 100.00 4 13 27.87 5 20 -32.01 6 22 134.05 7 24 138.86 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 99.488 4.01 1.62299 58.1 2 787.505 (variable) 3 93.036 1.50 1.88100 40.1 4 21.560 4.33 5 67.274 1.30 1.77250 49.6 6 18.920 6.91 7 -46.884 1.20 1.49700 81.6 8 49.769 0.25 9 34.412 5.29 1.91082 35.3 10 -116.738 (variable) 11 25.538 3.01 1.80420 46.5 12 130.744 2.00 13 (Aperture) ∞ (Variable) 14 22.282 4.28 1.61772 49.8 15 -25.543 0.70 1.90366 31.3 16 20.283 (variable) 17 26.540 0.90 1.87070 40.7 18 15.778 4.02 1.55032 75.5 19 -53.046 0.50 20 48.504 3.69 1.90366 31.3 21 -128.074 (variable) 22 39.053 1.20 1.87070 40.7 23 18.982 (variable) 24* -97.282 2.50 1.53110 55.9 25* -63.100 (variable) 26 -51.286 3.72 1.54072 47.2 27 -36.730 (variable) Image plane ∞ Aspheric data Page 24 K = 0.00000e+000 A 4=-5.69002e-005 A 6= 6.85123e-007 A 8=-1.19315e-008 A10= 5.69105e-011 Page 25 K = 0.00000e+000 A 4=-4.72971e-005 A 6= 4.93848e-007 A 8=-7.65618e-009 A10= 3.03899e-011 Various data Zoom ratio 2.89 Wide-angle Mid-range Telephoto Focal length 18.58 32.05 53.71 F-number 4.12 5.11 6.48 Half angle of view (°) 48.12 34.05 21.77 Image height 18.50 21.64 21.64 Lens length 116.12 122.10 149.69 BF 17.48 18.34 18.85 d 2 0.68 12.12 30.02 d10 29.09 10.59 1.20 d13 3.27 2.82 2.27 d16 1.29 1.74 2.29 d21 2.86 2.62 1.18 d23 7.39 7.63 9.07 d25 2.76 14.94 33.51 d27 17.48 18.34 18.85 Zoom lens group data Group starting plane focal length 1 1 182.38 2 3 -25.38 3 11 38.97 4 14 -42.28 5 17 21.61 6 22 -43.63 7 24 329.77 8 26 219.64 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 57.509 5.16 1.60311 60.6 2 205.096 (variable) 3 86.022 1.50 1.85150 40.8 4 21.448 2.69 5* 38.852 0.15 1.56039 36.6 6 40.313 1.30 1.77250 49.6 7 14.601 7.04 8 -57.247 1.20 1.49700 81.6 9 24.306 0.35 10 23.136 4.33 1.91082 35.3 11 310.933 (variable) 12 75.644 3.09 1.59282 68.6 13 -94.391 3.05 14 (Aperture) ∞ 2.93 15 73.587 7.10 1.55032 75.5 16 -13.553 1.30 1.80420 46.5 17 -26.222 (variable) 18 62.686 1.50 1.87070 40.7 19 17.806 8.90 1.59410 60.5 20 -37.108 (variable) 21 349.610 1.20 1.87070 40.7 22 32.301 (variable) 23* -797.162 2.50 1.53110 55.9 24* 910.780 (variable) 25 1862.912 5.35 1.51742 52.2 26 -36.134 (variable) Image plane ∞ Aspheric data 5th page K = 0.00000e+000 A 4=-1.78711e-006 A 6= 1.18552e-008 Page 23 K = 0.00000e+000 A 4=-6.82095e-005 A 6= 2.64141e-007 A 8=-1.97264e-009 A10= 5.95498e-012 Page 24 K = 0.00000e+000 A 4=-5.99353e-005 A 6= 2.04911e-007 A 8=-1.20640e-009 A10= 2.99152e-012 Various data Zoom ratio 2.70 Wide-angle Mid-range Telephoto Focal length 19.72 32.07 53.16 F-number 4.12 5.08 6.07 Half angle of view (°) 48.13 35.50 22.43 Image height 18.50 21.64 21.64 Lens length 126.89 137.98 162.14 BF 21.40 30.38 51.52 d 2 0.67 9.96 25.28 d11 24.10 10.74 0.80 d17 8.62 5.36 1.83 d20 4.53 6.06 6.02 d22 5.56 7.29 10.86 d24 1.37 7.55 5.19 d26 21.40 30.38 51.52 Zoom lens group data Group starting plane focal length 1 1 130.79 2 3 -19.20 3 12 33.06 4 18 69.01 5 21 -40.95 6 23 -800.00 7 25 68.57 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 62.063 1.50 1.77830 23.9 2 56.087 5.67 1.72916 54.7 3 207.626 (variable) 4 166.987 1.50 1.87070 40.7 5 19.406 6.48 6 93.194 1.30 1.75500 52.3 7 24.593 7.15 8 -38.893 1.20 1.49700 81.6 9 72.839 0.25 10 44.017 6.04 1.89190 37.1 11 -67.133 (variable) 12 -479.567 2.43 1.59282 68.6 13 -50.771 2.66 14 (Aperture) ∞ 0.90 15 26.572 4.02 1.55032 75.5 16 -18.947 1.00 1.75500 52.3 17 -104.111 5.33 18 34.297 1.00 1.87070 40.7 19 13.696 4.83 1.59410 60.5 20 -45.111 (variable) 21 41.785 1.20 1.87070 40.7 22 17.825 (variable) 23* -51.718 2.50 1.53110 55.9 24* -44.013 (variable) 25 -48.971 4.14 1.51742 52.2 26 -30.063 (variable) Image plane ∞ Aspheric data Page 23 K = 0.00000e+000 A 4= 7.20389e-006 A 6= 6.12510e-007 A 8=-8.74905e-009 A10= 4.44564e-011 Page 24 K = 0.00000e+000 A 4= 1.20516e-005 A 6= 3.59941e-007 A 8=-4.10774e-009 A10= 1.22521e-011 Various data Zoom ratio 3.18 Wide-angle Mid-range Telephoto Focal length 18.50 35.02 58.92 F-number 4.12 5.39 6.48 Half angle of view (°) 49.09 31.79 19.95 Image height 18.50 21.64 21.64 Lens total length 132.01 138.38 160.73 BF 24.47 23.18 37.26 d 3 0.52 11.91 26.34 d11 35.49 13.46 1.34 d20 3.04 2.21 0.60 d22 4.99 5.82 7.42 d24 2.40 20.70 26.66 d26 24.47 23.18 37.26 Zoom lens group data Group starting plane focal length 1 1 120.00 2 4 -26.16 3 12 25.31 4 21 -36.55 5 23 500.00 6 25 140.02 [Numerical Example 6] Unit: mm Surface Data Surface number rd nd νd 1 55.873 1.50 1.76182 26.5 2 51.326 5.35 1.71999 50.2 3 161.429 (variable) 4 129.661 1.50 1.87070 40.7 5 18.545 6.19 6 91.584 1.30 1.75500 52.3 7 24.609 6.73 8 -36.819 1.20 1.49700 81.5 9 82.954 0.25 10 43.868 5.83 1.89190 37.1 11 -66.028 (variable) 12 -562.956 3.00 1.59282 68.6 13 -53.369 4.84 14 (Aperture) ∞ 0.80 15 32.842 3.45 1.55032 75.5 16 -18.593 1.00 1.75500 52.3 17 -114.029 4.20 18 36.476 1.00 1.87070 40.7 19 15.972 5.33 1.59410 60.5 20 -43.901 (variable) 21 45.177 1.20 1.87070 40.7 22 19.683 (variable) 23* -50.553 2.50 1.53110 55.9 24* -38.515 (variable) 25 -52.948 4.01 1.51742 52.2 26 -32.289 (variable) Image plane ∞ Aspheric data Page 23 K = 0.00000e+000 A 4= 2.34212e-005 A 6= 2.65808e-007 A 8=-1.22942e-010 A10=-1.27940e-011 Page 24 K = 0.00000e+000 A 4= 2.47727e-005 A 6= 1.23081e-007 A 8= 1.24190e-009 A10=-1.64146e-011 Various data Zoom ratio 2.86 Wide-angle Mid-range Telephoto Focal length 20.60 35.03 58.91 F-number 4.12 5.20 6.31 Half angle of view (°) 45.90 32.29 20.22 Image height 18.80 21.64 21.64 Lens length 137.68 144.32 168.87 BF 27.10 27.92 45.41 d 3 0.69 10.05 23.93 d11 33.23 14.33 1.58 d20 3.91 2.99 0.58 d22 4.71 5.64 8.05 d24 6.84 22.21 28.13 d26 27.10 27.92 45.41 Zoom lens group data Group starting plane focal length 1 1 116.29 2 4 -26.23 3 12 27.33 4 21 -40.96 5 23 284.07 6 25 150.00 The various values ​​in each numerical example are summarized in Table 1 below.

[0086] [Table 1]

[0087] [Imaging device] Next, an embodiment of a digital still camera (imaging device) 10 that uses a zoom lens of the present invention as an imaging optical system will be described with reference to Fig. 13. In Fig. 13, 13 denotes a camera body, and 11 denotes an imaging optical system configured with any of the zoom lenses described in Examples 1 to 6. 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 imaging optical system 11. Camera body 13 may be a so-called single-lens reflex camera that has a quick-turn mirror, or a so-called mirrorless camera that does not have a quick-turn mirror.

[0088] In this way, by applying the zoom lens of the present invention to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained.

[0089] 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]

[0090] L1 First lens group L2 Second lens group L3: Third lens group

Claims

1. A zoom lens having six or more lens groups, which are arranged in order from the object side to the image side, including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, and in which the spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, the first lens group moves, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases. the first lens group is composed of one positive lens, the second lens group comprises three single lens elements, each having a negative refractive power, arranged successively in order from the object side to the image side; When the shape factor of the second single lens element adjacent to the first single lens element closest to the object among the three single lens elements is SFY, the focal length of the first lens group is f1, and the focal length of the second lens group is f2, 1.715<SFY<10.0 -7.5<f1 / f2<-0.5 A zoom lens characterized by satisfying the following conditions:

2. A zoom lens having six or more lens groups, which are arranged in order from the object side to the image side, including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power, and in which the spacing between adjacent lens groups changes during zooming, During zooming from the wide-angle end to the telephoto end, the first lens group moves, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases. the first lens group is composed of one lens element having a positive refractive power, the second lens group comprises three single lens elements, each having a negative refractive power, arranged successively in order from the object side to the image side; When the shape factor of the second single lens element adjacent to the first single lens element closest to the object among the three single lens elements is SFY, the focal length of the first lens group is f1, the focal length of the second lens group is f2, and the focal length of the third single lens element closest to the image among the three single lens elements is fZ, 1.715<SFY<10.0 -7.5<f1 / f2<-0.5 0.5<fZ / f2<1.96 A zoom lens characterized by satisfying the following conditions:

3. When the shape factor of the first single lens element is SFX, 1.0<SFX<3.0 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. When the shape factor of one positive lens in the first lens group or one element lens with positive refractive power in the first lens group is SF1, 0.6<SF1<3.0 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. Of the three single lens elements, the refractive indexes at the d-line of the first single lens element closest to the object side and the third single lens element closest to the image side are nX and nZ, respectively. 1.19<nX / nZ<1.31 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. When the focal length of the first single lens element is fX and the focal length of the second single lens element is fY, 0.35<fX / fY<1.50 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the first single lens element is fX, 0.70<fX / f2<2.20 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. When the focal length of the zoom lens at the wide-angle end is fw and the back focus of the zoom lens at the wide-angle end is skw, 0.90<skw / fw<1.45 8. The zoom lens according to claim 1, wherein the following condition is satisfied:

9. When the focal length of the zoom lens at the wide-angle end is fw, 5.1<f1 / fw<14.0 9. The zoom lens according to claim 1, wherein the following condition is satisfied:

10. When the focal length of the third lens group is f3 and the focal length of the zoom lens at the telephoto end is ft, 0.38<f3 / ft<2.00 10. The zoom lens according to claim 1, wherein the following condition is satisfied:

11. When the third-order aberration coefficient of distortion at the wide-angle end is V, 0.3<V<1.0 11. The zoom lens according to claim 1, wherein the following condition is satisfied:

12. 12. The zoom lens according to claim 1, wherein the zoom lens comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, and a rear group including three or more lens groups, and the rear group includes, arranged in order from the object side to the image side, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, and a sixth lens group.

13. 12. The zoom lens according to claim 1, wherein the zoom lens comprises, arranged in order from the object side to the image side, the first lens group, the second lens group, the third lens group, and a rear group including three or more lens groups, and the rear group includes, arranged in order from the object side to the image side, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, and a sixth lens group.

14. 14. An imaging device comprising: the zoom lens according to claim 1; and an imaging element that receives an image formed by the zoom lens.

Images