Zoom lens and imaging device having the same

Abstract

To provide a negative-lead zoom lens which is compact and has a wide-angle, and yet offers superior optical performance over a wide zoom range.SOLUTION: A zoom lens L0 comprises a first lens group L1 having negative refractive power, an intermediate group Lm including one or more lens groups, and a final lens group having positive refractive power. The first lens group L1 comprises a first negative lens, second negative lens, and third negative lens arranged successively in order from an object side to an image side. The first lens group L1 comprises four or less negative lenses. The intermediate group Lm comprises a plurality of cemented lenses having bonding surfaces that are convex toward the object side, and a lens element Ln located on the most image side among lens elements having negative refractive power in the intermediate group Lm. The zoom lens L0 satisfies given conditional expressions.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a zoom lens and the like, and is suitable for imaging devices such as digital video cameras, digital still cameras, broadcast cameras, and silver halide film cameras.

Background Art

[0002] As a zoom lens in which the entire lens system is small and wide-angle conversion is easy, a negative lead type zoom lens in which a lens group having a negative refractive power is arranged on the object side most is known.

[0003] Patent Document 1 describes a negative lead type zoom lens composed of five lens groups.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a negative lead type zoom lens, since the lens configuration is asymmetric, there is a problem that it is difficult to correct various aberrations. For example, in order to achieve a wide-angle conversion in a negative lead type zoom lens, it is necessary to increase the refractive power of the first lens group having a negative refractive power. However, in this case, various aberrations such as longitudinal chromatic aberration in the wide-angle region are likely to occur largely.

[0006] In order to obtain high optical performance while making the optical system small and wide-angle in a negative lead type zoom lens, it is necessary to appropriately configure a lens group arranged on the image side of the aperture stop in order to correct various aberrations generated in the first lens group having a strong refractive power. However, the zoom lens described in Patent Document 1 was not always sufficient in this regard.

[0007] Therefore, the present invention aims to realize a negative lead zoom lens that is compact and has a wide angle of view, while also possessing high optical performance over a wide zoom range. [Means for solving the problem]

[0008] The zoom lens of the present invention comprises a first group of negative refractive lenses arranged sequentially from the object side to the image side, Consists of a second lens group with positive refractive power. A zoom lens comprising an intermediate group and a final lens group with positive refractive power, wherein the spacing between adjacent lens groups changes during zooming, the zoom lens has an aperture diaphragm, the first lens group has a first negative lens, a second negative lens, and a third negative lens arranged in sequence from the object side to the image side, the number of negative lenses included in the first lens group is four or less, the intermediate group has a plurality of cemented lenses having a cemented surface that is convex on the object side, and the negative refractive power lens element included in the intermediate group that is positioned furthest towards the image side A lens element Ln is present, and the focal length of the first lens group is f1, the focal length of the zoom lens at the wide-angle end is fw, the distance along the optical axis from the lens surface closest to the object of the zoom lens at the wide-angle end to the aperture diaphragm is L1s, the distance along the optical axis from the aperture diaphragm at the wide-angle end to the lens surface closest to the image of the lens element Ln is Lsn, the focal length of the lens element Ln is fn, and the Abbe number of the lens L1n with the largest Abbe number for the d line among the negative lens materials included in the first lens group is νd1n. 1.2 < |f1| / fw < 2.0 0.5 <L1s / Lsn<1.8 0.7 < |fn| / Lsn < 2.0 80.0 < νd1n < 100.0 It is characterized by satisfying the following conditional expression. [Effects of the Invention]

[0009] According to the present invention, a negative lead zoom lens can be realized that is compact and has a wide angle of view while possessing high optical performance over a wide zoom range. [Brief explanation of the drawing]

[0010] [Figure 1] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 1. [Figure 2] It is an aberration diagram of the zoom lens of Example 1. [Figure 3] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 2. [Figure 4] It is an aberration diagram of the zoom lens of Example 2. [Figure 5] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 3. [Figure 6] It is an aberration diagram of the zoom lens of Example 3. [Figure 7] It is a lens cross-sectional view at the wide-angle end of the zoom lens of Example 4. [Figure 8] It is an aberration diagram of the zoom lens of Example 4. [Figure 9] It is a schematic diagram showing an imaging device.

Embodiments for Carrying Out the Invention

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

[0012] FIGS. 1, 3, 5, and 7 are cross-sectional views of the zoom lenses L0 of Examples 1 to 4 at the wide-angle end, respectively. The zoom lens L0 of each example is an imaging lens system used in imaging devices such as video cameras, digital cameras, TV cameras, surveillance cameras, and silver halide film cameras. In the lens cross-sectional view, the left side is the subject side (object side) (front), and the right side is the image side (rear).

[0013] The zoom lens L0 of each embodiment has a first lens group L1 with negative refractive power, an intermediate group Lm including one or more lens groups, and a final lens group with positive refractive power. In the present specification, the "lens group" is a moving unit during zooming (a component of the zoom lens that moves integrally or remains stationary during zooming). That is, the distance between adjacent lens groups changes during zooming. A lens group is composed of one or more lenses. Also, a lens group may include an aperture stop.

[0014] In the zoom lenses L0 of Examples 1 and 4, the intermediate group Lm consists of a second lens group L2 with positive refractive power and a third lens group L3 with positive refractive power. Also, the final lens group is a fourth lens group L4 with positive refractive power.

[0015] In the zoom lens L0 of Example 2, the intermediate group Lm consists of a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, and a fourth lens group L4 with negative refractive power. Also, the final lens group is a fifth lens group L5 with positive refractive power.

[0016] In the zoom lens L0 of Example 3, the intermediate group Lm consists of a second lens group L2 with positive refractive power. Also, the final lens group is a third lens group L3 with positive refractive power.

[0017] In the lens cross-sectional view, SP is the aperture stop, and in Examples 1 to 4, it is arranged between the first lens group L1 and the second lens group L2.

[0018] In each cross-sectional view, IP is the image plane. When the zoom lens L0 of each embodiment is used for a digital video camera or a digital still camera, the imaging surface of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is arranged on the image plane IP. When the zoom lens L0 of each embodiment is used as an imaging zoom lens for a silver salt film camera, the photosensitive surface of the film is arranged on the image plane IP.

[0019] Also, each cross-sectional view shows the trajectory during zooming and the trajectory during focusing.

[0020] Specifically, in Examples 1-4, when changing magnification from the wide-angle end to the telephoto end, the first lens group L1 moves in a convex trajectory toward the image side (a trajectory that moves toward the image side and then toward the object side). By moving in this manner, sufficient magnification ratio can be ensured while effectively correcting field curvature in the intermediate zoom region, although other trajectories may also be used. In addition, the second lens group L2 moves toward the object side when changing magnification.

[0021] In Examples 1, 2, and 4, the third lens group L3 moves toward the object when the magnification changes from the wide-angle end to the telephoto end. In Example 3, the third lens group L3 is fixed relative to the image plane during magnification.

[0022] In Example 2, when changing magnification from the wide-angle end to the telephoto end, the fourth lens group L4 moves toward the object.

[0023] In Examples 1 and 4, the fourth lens group L4 is fixed relative to the image plane during magnification.

[0024] Furthermore, in Example 2, the fifth lens group L5 is fixed to the image plane during magnification.

[0025] Furthermore, in Examples 1-4, focusing from an object at infinity to a near-field object is achieved by moving all or part of the second lens group L2 toward the image, as indicated by the dotted arrows. Multiple lens groups may be moved along different trajectories during focusing.

[0026] Figures 2, 4, 6, and 8 show the aberration diagrams of the zoom lenses of each embodiment at infinity focus. In each aberration diagram, (A) corresponds to the wide-angle end, (B) to the intermediate zoom position, and (C) to the telephoto end.

[0027] In the spherical aberration diagram, FNo is the F-number. In the spherical aberration diagram, the amount of spherical aberration for the d-line (wavelength 587.6 nm) and the g-line (wavelength 435.8 nm) is shown by a solid line and a dashed line, respectively. In the astigmatism diagram, ΔS is the amount of astigmatism at the sagittal image plane (solid line), and ΔM is the amount of astigmatism at the meridional image plane (dashed line). In the distortion diagram, the amount of distortion for the d-line is shown. In the chromatic aberration diagram, the amount of chromatic aberration at the g-line is shown. Note that ω is the half-angle of view (°).

[0028] Next, the characteristic configuration and conditions of the zoom lens L0 in each embodiment will be described.

[0029] The zoom lens L0 in each embodiment has three negative lenses (first negative lens, second negative lens, and third negative lens) arranged in a sequence from the object side to the image side in the first lens group L1. By arranging at least three negative lenses in a sequence in this way, the refractive power of each negative lens can be appropriately distributed, thereby effectively correcting coma aberration, field curvature, and distortion at the wide-angle end.

[0030] Furthermore, in each embodiment of the zoom lens L0, the number of negative lenses included in the first lens group L1 is limited to four or fewer. This prevents the first lens group L1 from becoming excessively large.

[0031] Furthermore, the intermediate group Lm has multiple cemented lenses, each having a convex bonding surface on the object side. By providing multiple cemented lenses in the intermediate group Lm, axial chromatic aberration and lateral chromatic aberration can be effectively corrected over a wide zoom range. In particular, by providing multiple cemented lenses with a convex bonding surface on the object side, it becomes possible to effectively correct lateral chromatic aberration at the wide-angle end.

[0032] Furthermore, the intermediate group Lm includes a negative refractive power lens element Ln, which is positioned furthest towards the image side among the negative refractive power lens elements included in the intermediate group Lm. In this specification, "lens element" refers to a single lens or a cemented lens composed of multiple lenses joined together, with both sides of the lens in contact with the air.

[0033] Furthermore, the zoom lens L0 of each embodiment is configured to satisfy the following condition.

[0034] 1.2 < |f1| / fw < 2.0 (1) 0.5 <L1s / Lsn<1.8 (2) 0.7 < |fn| / Lsn < 2.0 (3) Here, f1 is the focal length of the first lens group L1. fw is the focal length of the zoom lens L0 at the wide-angle end. L1s is the distance along the optical axis from the lens surface closest to the object of the zoom lens L0 to the aperture diaphragm SP at the wide-angle end. Lsn is the distance along the optical axis from the aperture diaphragm SP to the lens surface closest to the image of the lens element Ln at the wide-angle end. fn is the focal length of the lens element Ln.

[0035] Conditional equation (1) is a conditional equation that defines the ratio of the focal length of the first lens group L1 to the focal length at the wide-angle end in order to achieve a wide angle of view while effectively correcting off-axis aberrations such as chromatic aberration at the wide-angle end.

[0036] If the absolute value of the focal length of the first lens group L1 exceeds the upper limit of condition (1), it becomes difficult to achieve a wide angle of view while miniaturizing the zoom lens L0.

[0037] When the absolute value of the focal length of the first lens group L1 falls below the lower limit of condition (1), it becomes difficult to correct off-axis aberrations such as chromatic aberration at the wide-angle end.

[0038] Conditional equation (2) is a conditional equation that defines the conditions for achieving both off-axis aberration correction at the wide-angle end and miniaturization of the zoom lens L0.

[0039] If the distance from the lens surface closest to the object in the first lens group L1 to the aperture diaphragm SP becomes longer than the upper limit of condition (2), the diameter of the first lens group L1, which is necessary to ensure sufficient peripheral light at the wide-angle end, will increase.

[0040] Alternatively, if the distance from the aperture diaphragm SP to the image-side lens surface of the lens element Ln becomes shorter than the upper limit of condition (2), the separation of on-axis and off-axis light beams passing through the lens element Ln becomes insufficient at the wide-angle end. In that case, it becomes difficult to adequately correct off-axis aberrations with the lens element Ln.

[0041] If the distance from the aperture diaphragm SP to the image-side lens surface of the lens element Ln becomes longer, below the lower limit of condition (2), the lens element Ln required to ensure sufficient peripheral illumination at the wide-angle end will become larger.

[0042] Conditional equation (3) is a conditional equation that defines the ratio of the focal length of the lens element Ln to the distance from the aperture diaphragm SP to the image-side lens surface of the lens element Ln, in order to achieve both off-axis aberration correction at the wide-angle end and miniaturization of the entire optical system.

[0043] If the absolute value of the focal length of lens element Ln exceeds the upper limit of condition (3), or falls below the lower limit, the off-axis aberration correction at the wide-angle end will not be sufficiently performed.

[0044] With the above configuration, it is possible to realize the L0 zoom lens, which is compact, has a wide field of view, and yet possesses high optical performance over a wide zoom range.

[0045] Furthermore, it is more preferable to set at least one of the upper and lower limits of the numerical range in conditional expressions (1) to (3) as shown in conditional expressions (1a) to (3a), and even more preferable as shown in conditional expressions (1b) to (3b).

[0046] 1.3 < |f1| / fw < 1.8 (1a) 0.8 <L1s / Lsn<1.6 (2a) 0.8 < |fn| / Lsn < 1.7 (3a) 1.4 < |f1| / fw < 1.6 (1b) 1.2 <L1s / Lsn<1.5 (2b) 0.9 < |fn| / Lsn < 1.4 (3b)

[0047] Next, we will describe the conditions that the zoom lens L0 of each embodiment preferably satisfies. The zoom lens L0 of each embodiment preferably satisfies one or more of the following conditional expressions.

[0048] 2.0 <fmw / fw<3.6 (4) 0.70 <f11 / f12<2.00 (5) 1.0 < |fn| / skn < 3.0 (6) 1.0 <fL / |fn|<5.0 (7) 70.0 < νd1n < 100.0 (8) 1.5 <f1n / f1<3.0 (9) 35.0 < νdmp - νdmn < 70.0 (10)

[0049] Here, fmw is the focal length of the intermediate group Lm at the wide-angle end. f11 is the focal length of the negative lens L11, which is located furthest towards the object in the first lens group L1. f12 is the focal length of the negative lens L12, which is located adjacent to the image side of the negative lens L11. skn is the distance along the optical axis from the lens surface furthest towards the image to the image plane IP of the lens element Ln. fL is the focal length of the final lens group. νd1n and f1n are the Abbe number and focal length of the negative lens L1n, which has the largest Abbe number for the d line among the negative lenses included in the first lens group L1. νdmn is the Abbe number for the d line of the negative lens included in the cemented lens Lmc, which is located furthest towards the image among the cemented lenses that are included in the intermediate group Lm and have a cemented surface with a convex surface facing the object. νdmp is the Abbe number for the d line of the positive lens included in the cemented lens Lmc.

[0050] Conditional equation (4) is a conditional equation that defines the preferred conditions for achieving miniaturization of the zoom lens L0 while effectively correcting various aberrations over a wide zoom range.

[0051] If the focal length of the intermediate group Lm becomes longer than the upper limit of condition (4), the amount of movement of the lens group included in the intermediate group Lm becomes large when changing magnification from the wide-angle end to the telephoto end, making it difficult to sufficiently miniaturize the entire zoom lens L0.

[0052] When the focal length of the intermediate group Lm becomes shorter than the lower limit of condition equation (4), it becomes difficult to sufficiently suppress the fluctuations of various aberrations that occur during magnification.

[0053] Conditional equation (5) is a conditional equation that defines a desirable ratio of the focal lengths of negative lenses L11 and L12 in order to achieve both miniaturization of the first lens group L1 and correction of off-axis aberrations at the wide-angle end.

[0054] If the focal length of the negative lens L11 becomes longer than the upper limit of condition (5), the outer diameter of the negative lens L11 increases, making sufficient miniaturization difficult.

[0055] If the focal length of the negative lens L11 becomes shorter than the lower limit of condition (5), it becomes difficult to adequately correct off-axis aberrations at the wide-angle end.

[0056] Conditional equation (6) is a conditional equation that defines a desirable ratio between the focal length of lens element Ln and the distance from the image-side lens surface to the image plane of lens element Ln in order to ensure telecentricity on the image side at the wide-angle end while effectively correcting off-axis aberrations.

[0057] If the absolute value of the focal length of the lens element Ln exceeds the upper limit of condition (6), it becomes difficult to adequately correct off-axis aberrations at the wide-angle end.

[0058] If the focal length of lens element Ln becomes shorter than the lower limit of condition (6), it becomes difficult to ensure sufficient telecentricity on the image side at the wide-angle end.

[0059] Conditional equation (7) is a conditional equation that defines a desirable ratio between the focal length of the final lens group and the focal length of the lens element Ln in order to ensure telecentricity on the image side at the wide-angle end while effectively correcting off-axis aberrations.

[0060] If the focal length of the final lens group exceeds the upper limit of condition (7), it becomes difficult to ensure sufficient telecentricity on the image side at the wide-angle end.

[0061] If the focal length of the final lens group becomes shorter than the lower limit of condition (7), it becomes difficult to adequately correct off-axis aberrations at the wide-angle end.

[0062] Conditional equation (8) is a conditional equation that defines a preferred range for the Abbe number of the negative lens included in the first lens group L1 in order to effectively correct axial chromatic aberration and lateral chromatic aberration at the wide-angle end.

[0063] By having at least one negative lens in the first lens group L1 that satisfies condition (8), it becomes possible to better correct axial chromatic aberration and lateral chromatic aberration at the wide-angle end. If the upper or lower limit of condition (8) is exceeded, axial chromatic aberration and lateral chromatic aberration tend to be overcorrected or undercorrected.

[0064] Conditional equation (9) is a conditional equation that defines a desirable ratio between the focal length of the negative lens L1n and the focal length of the first lens group L1 in order to effectively correct axial chromatic aberration and lateral chromatic aberration at the wide-angle end, while also effectively correcting other off-axis aberrations.

[0065] If the focal length of the negative lens L1n becomes longer than the upper limit of condition (9), it becomes difficult to adequately correct axial chromatic aberration and lateral chromatic aberration at the wide-angle end.

[0066] If the focal length of the negative lens L1n becomes shorter, falling below the lower limit of condition (9), it becomes difficult to correct off-axis aberrations such as coma and field curvature at the wide-angle end.

[0067] Conditional equation (10) is a conditional equation that defines the preferred difference between the Abbe number of the negative lens and the Abbe number of the positive lens included in the cemented lens Lmc for good correction of chromatic aberration at the wide-angle end.

[0068] By configuring the cemented lens Lmc to satisfy condition (10), it becomes possible to better correct chromatic aberration at the wide-angle end. If the upper or lower limit of condition (10) is exceeded, chromatic aberration at the wide-angle end is likely to be overcorrected or undercorrected.

[0069] Furthermore, it is preferable that at least one of the upper or lower limits of conditional expressions (4) to (10) be the values ​​specified in the following conditional expressions (4a) to (10a).

[0070] 2.2 <fmw / fw<3.4 (4a) 0.75 <f11 / f12<1.95 (5a) 1.3 < |fn| / skn < 2.8 (6a) 1.3 <fL / |fn|<4.0 (7a) 75.0 < νd1n < 98.0 (8a) 1.7 <f1n / f1<2.7 (9a) 40.0 < νdmp - νdmn < 65.0 (10a)

[0071] Furthermore, it is preferable that at least one of the upper or lower limits of conditional expressions (4) to (10) be the values ​​defined in the following conditional expressions (4b) to (10b).

[0072] 2.4 <fmw / fw<3.2 (4b) 0.80 <f11 / f12<1.90 (5b) 1.5 < |fn| / skn < 2.7 (6b) 1.7 <fL / |fn|<3.5 (7b) 80.0 < νd1n < 96.0 (8b) 1.9 <f1n / f1<2.5 (9b) 45.0 < νdmp - νdmn < 60.0 (10b) Next, the configuration of the zoom lens L0 in each embodiment will be described in more detail. It is not necessarily required for the zoom lens L0 to have the configuration described below in order to implement the present invention.

[0073] In Examples 1 to 3, the first lens group L1 consists of a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a fourth lens with negative refractive power, and a fifth lens with positive refractive power, arranged in order from the object side to the image side. On the other hand, in Example 4, the first lens group L1 consists of a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power, a fourth lens with positive refractive power, and a fifth lens with negative refractive power, arranged in order from the object side to the image side.

[0074] In Example 1, the second lens group L2 of the intermediate group Lm consists of a first cemented lens formed by joining a negative lens and a positive lens, and a second cemented lens formed by joining a negative lens and a positive lens, arranged in order from the object side to the image side. The third lens group L3 of the intermediate group Lm consists of a third cemented lens formed by joining a negative lens and a positive lens, a positive lens, a negative lens, a fourth cemented lens formed by joining a negative lens and a positive lens, and a negative lens, arranged in order from the object side to the image side.

[0075] In Example 2, the second lens group L2 of the intermediate group Lm consists of a first cemented lens formed by joining a negative lens and a positive lens, and a second cemented lens formed by joining a negative lens and a positive lens, arranged sequentially from the object side to the image side. The third lens group L3 of the intermediate group Lm consists of a third cemented lens formed by joining a negative lens and a positive lens, a negative lens, and a fourth cemented lens formed by joining a negative lens and a positive lens, arranged sequentially from the object side to the image side. The fourth lens group L4 of the intermediate group Lm consists of a fifth cemented lens formed by joining a negative lens and a positive lens.

[0076] In Example 3, the intermediate group Lm consists of a first bonded lens formed by joining a negative lens and a positive lens, a second bonded lens formed by joining a negative lens and a positive lens, a third bonded lens formed by joining a negative lens and a positive lens, a negative lens, a fourth bonded lens formed by joining a negative lens and a positive lens, and a negative lens.

[0077] In Example 4, the second lens group L2 of the intermediate group Lm consists of a first cemented lens formed by joining a negative lens and a positive lens, and a second cemented lens formed by joining a negative lens and a positive lens, arranged in order from the object side to the image side. The third lens group L3 of the intermediate group Lm consists of a third cemented lens formed by joining a negative lens and a positive lens, a negative lens, a fourth cemented lens formed by joining a negative lens and a positive lens, and a negative lens, arranged in order from the object side to the image side.

[0078] Furthermore, in Examples 1 to 4, the final lens group consists of a single positive lens. By adopting this configuration, it becomes easy to ensure good telecentricity on the image side over a wide zoom range, while maintaining a compact size.

[0079] Next, the numerical examples corresponding to Examples 1 to 4 are shown.

[0080] In each numerical example, each surface of the zoom lens is assigned a surface number i (where i is a natural number) from the object side. r is the radius of curvature of each surface (mm), d is the lens thickness or distance (air gap) on the optical axis between surface number i and surface number (i+1) (mm), and nd is the refractive index of the material of the optical component having each surface with respect to the d line. νd is the Abbe number of the material of the optical component having each surface with respect to the d line.

[0081] The Abbe number is defined as νd = (Nd-1) / (NF-NC), where NF, Nd, and NC are the refractive indices of the material for the F line (486.1 nm), d line (587.6 nm), and C line (656.3 nm), respectively.

[0082] Furthermore, aspherical surfaces are indicated with an asterisk (*) in the surface data. The aspherical shape is defined by the following equation, where k is the eccentricity, A4, A6, A8, A10... are the aspherical coefficients, and x is the displacement in the optical axis direction (relative to the surface vertex) at a height h from the optical axis. Here, R is the radius of paraxial curvature. x=( h 2 / R) / [1+[1-(1+k)(h / R) 2 ] 1 / 2 ]+A4h4 +A6h 6 +A8h 8 +A10h 10 ...

[0083] Furthermore, the total length of the lens is the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final lens surface (the lens surface closest to the image) of the zoom lens, plus the back focus. The back focus is the distance from the final lens surface of the zoom lens to the image plane IP (paraxial image plane).

[0084] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd 1* 56.099 3.50 1.77250 49.6 2 24.246 8.52 3 34.584 2.30 1.95375 32.3 4 17.382 8.52 5* 200.682 2.30 1.58313 59.4 6* 20.705 10.73 7 -101.447 1.20 1.49700 81.5 8 18.222 4.62 1.73800 32.3 9 478.584 (variable) 10 (aperture) ∞ (variable) 11 23.744 1.00 1.92286 18.9 12 10.960 6.27 1.79952 42.2 13 673.725 0.84 14 -42.651 1.00 1.90043 37.4 15 13.238 5.04 1.89286 20.4 16 -61.427 (variable) 17 25.139 1.20 2.00100 29.1 18 14.087 4.82 1.49700 81.5 19 19447.656 0.15 20 22.378 6.50 1.49700 81.5 21 -22.245 0.20 22 -49.519 1.10 1.90043 37.4 23 46.100 0.20 24 21.126 1.50 2.00100 29.1 25 13.367 7.91 1.49700 81.5 26 -66.503 1.40 27 -27.449 1.50 1.85400 40.4 28* -60.322 (variable) 29 -133.157 4.74 1.51633 64.1 30 -40.481 15.09 Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 8.54297e-006 A 6=-8.01798e-009 A 8= 1.13131e-011 A10=-8.67813e-015 A12= 4.66323e-018 5th page K = 0.00000e+000 A 4= 8.35841e-005 A 6=-3.26135e-007 A 8= 5.57011e-010 A10= 4.18922e-015 Side 6 K =-1.40479e+000 A 4= 1.30666e-004 A 6=-2.26421e-007 A 8=-1.41303e-009 A10= 7.47871e-012 Page 28 K = 0.00000e+000 A 4= 3.33336e-005 A 6= 4.06563e-008 A 8=-2.92759e-010 A10= 1.68963e-013 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 10.30 14.90 19.40 F-number 4.12 4.12 4.12 Half-angle (degrees): 62.03, 54.38, 48.12 Image height 19.40 20.80 21.64 Lens length: 129.14, 128.47, 132.69 BF 15.09 15.09 15.09 d 9 17.80 7.34 2.00 d10 1.30 1.48 1.50 d16 2.64 2.46 2.44 d28 5.26 15.05 24.61 Zoom lens group data Group starting plane focal length 1 1 -14.49 2 11 49.35 3 17 56.81 4 29 110.72 Single lens data Lens starting plane, focal length 1 1 -58.06 2 3 -39.20 3 5 -39.78 4 7 -30.98 5 8 25.56 6 11 -22.92 7 12 13.88 8 14 -11.12 9 15 12.60 10 17 -33.85 11 18 28.36 12 20 23.59 13 22 -26.37 14 24 -40.25 15 25 23.16 16 27 -60.25 17 29 110.72

[0085] [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1* 41.574 3.50 1.58313 59.4 2* 13.158 8.70 3 62.750 2.30 1.77250 49.6 4 21.374 6.69 5* 137.929 2.30 1.85400 40.4 6* 27.160 6.58 7 -33.966 1.20 1.49700 81.5 8 33.106 0.20 9 27.579 6.16 1.73800 32.3 10 -57.136 (variable) 11 (aperture) ∞ (variable) 12 16.161 1.00 1.92286 18.9 13 10.885 4.57 1.57840 62.8 14 165.918 1.11 15 -50.285 1.00 1.87070 40.7 16 12.492 4.81 1.84666 23.9 17 -54.788 (variable) 18 18.101 1.20 1.91082 35.3 19 12.663 7.47 1.49700 81.5 20 -18.043 0.20 21 -22.014 1.10 1.90043 37.4 22 -193.865 0.20 23 19.500 1.50 1.95375 32.3 24 12.666 7.22 1.49700 81.5 25 -58.816 (variable) 26* -77.191 1.50 1.85400 40.4 27 21.824 6.54 1.49700 81.5 28 -54.068 (variable) 29 -248.857 3.55 1.84666 23.8 30 -63.598 15.37 Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4=-8.50776e-006 A 6= 1.14899e-008 A 8=-8.44163e-012 A10= 3.70796e-015 2nd side K =-1.75103e+000 A 4= 3.67876e-005 A 6=-1.21075e-007 A 8= 2.76245e-011 A10= 1.64998e-013 A12=-1.20578e-016 5th page K = 0.00000e+000 A 4= 6.19388e-006 A 6=-8.51252e-008 A 8= 1.61905e-010 Side 6 K = 2.88261e+000 A 4= 2.27718e-005 A 6=-2.18414e-008 A 8= 2.74384e-011 Page 26 K = 0.00000e+000 A 4=-4.20828e-005 A 6= 2.55787e-008 A 8=-4.64042e-010 A10= 6.61699e-012 A12= 4.68151e-015 Various data Zoom ratio 1.88 Wide-angle, Medium, Telephoto Focal length 9.27 12.80 17.46 F-number 4.12 4.12 4.12 Half-angle (degrees): 64.34, 58.27, 51.10 Image height 19.30 20.70 21.64 Lens length: 124.52, 121.90, 125.00 BF 15.37 15.37 15.37 d10 19.78 9.25 2.00 d11 1.35 1.41 1.40 d17 2.66 2.73 2.71 d25 1.62 1.86 2.00 d28 3.13 10.67 20.92 Zoom lens group data Group starting plane focal length 1 1 -14.47 2 12 50.84 3 18 33.54 4 26 -58.19 5 29 100.02 Single lens data Lens starting plane, focal length 1 1 -34.58 2 3 -43.00 3 5 -39.98 4 7 -33.53 5 9 26.01 6 12 -39.74 7 13 19.92 8 15 -11.41 9 16 12.42 10 18 -51.72 11 19 16.29 12 21 -27.66 13 23 -42.45 14 24 21.70 15 26 -19.78 16 27 32.21 17 29 100.02

[0086] [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 34.400 3.50 1.58313 59.4 2* 16.622 10.11 3 40.381 2.30 2.00100 29.1 4 17.403 8.13 5* 90.700 2.30 1.58313 59.4 6* 27.050 6.71 7 -33.600 1.20 1.49700 81.5 8 35.822 0.20 9 30.640 5.08 1.78096 31.2 10 -75.913 (variable) 11 (aperture) ∞ 1.40 12 24.524 1.00 1.92286 18.9 13 12.510 4.95 1.82301 44.0 14 180.357 2.32 15 -59.078 1.00 1.87070 40.7 16 13.098 5.42 1.80810 22.8 17 -68.419 3.22 18 19.012 1.20 2.00100 29.1 19 16.008 6.10 1.49700 81.5 20 -25.440 0.20 21 -36.496 1.10 1.90043 37.4 22 103.580 0.20 23 18.461 1.50 2.05090 26.9 24 11.671 10.18 1.49700 81.5 25 -29.723 0.91 26 -24.961 1.50 1.85400 40.4 27* -72.116 (variable) 28 -264.561 4.01 1.48749 70.2 29 -55.806 16.34 Image plane ∞ Aspherical data 2nd side K =-5.53262e-001 A 4=-4.77532e-007 A 6=-1.10588e-008 A 8= 1.83751e-011 A10=-1.16497e-013 5th page K = 0.00000e+000 A 4= 8.88984e-006 A 6= 7.13658e-009 A 8=-3.04399e-011 Side 6 K = 1.23047e+000 A 4= 1.72971e-005 A 6= 1.91288e-008 A 8= 1.94281e-010 Page 27 K = 0.00000e+000 A 4= 2.82781e-005 A 6= 2.15940e-008 A 8=-4.36051e-010 A10= 1.38022e-012 A12=-1.58613e-014 Various data Zoom ratio 2.05 Wide-angle, Medium, Telephoto Focal length 11.33 16.19 23.28 F-number 4.12 4.12 4.12 Half-angle (degrees): 59.58, 52.36, 42.90 Image height 19.30 21.00 21.64 Lens length: 130.00 127.14 131.90 BF 16.34 16.34 16.34 d10 22.38 10.46 2.00 d27 5.54 14.61 27.83 Zoom lens group data Group starting plane focal length 1 1 -17.42 2 12 28.97 3 28 144.17 Single lens data Lens starting plane, focal length 1 1 -59.47 2 3 -32.17 3 5 -66.99 4 7 -34.69 5 9 28.55 6 12 -28.82 7 13 16.12 8 15 -12.23 9 16 14.02 10 18 -126.51 11 19 20.79 12 21 -29.86 13 23 -34.05 14 24 18.36 15 26 -45.37 16 28 144.17

[0087] [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1* 56.725 3.50 1.58313 59.4 2* 16.247 8.00 3 47.182 2.30 1.85150 40.8 4 16.606 13.49 5* -27.537 2.30 1.43875 94.7 6* 48.093 1.58 7 31.644 5.30 1.73800 32.3 8 -46.000 0.40 9 -38.000 1.20 1.80400 46.5 10 -176.688 (variable) 11 (aperture) ∞ (variable) 12 20.075 1.00 1.92286 18.9 13 11.750 4.80 1.66672 48.3 14 -366.339 0.52 15 -54.856 1.00 1.87070 40.7 16 12.212 4.92 1.84666 23.9 17 -93.053 (variable) 18 16.685 1.20 1.91082 35.3 19 12.147 7.91 1.49700 81.5 20 -19.012 0.20 21 -28.442 1.10 1.90043 37.4 22 174.067 0.20 23 18.819 1.50 1.95375 32.3 24 11.822 9.62 1.49700 81.5 25 -29.854 1.00 26 -20.390 1.50 1.85400 40.4 27* -55.000 (variable) 28 277.215 3.50 1.84666 23.9 29 -157.100 13.00 Image plane ∞ Aspherical data Front page K = 0.00000e+000 A 4= 2.73444e-006 A 6=-2.04458e-010 A 8=-1.10710e-012 A10= 8.13351e-016 2nd side K =-1.08469e+000 A 4= 5.05865e-006 A 6=-4.69295e-009 A 8= 1.90605e-013 A10=-1.15249e-013 A12= 1.09903e-016 5th page K = 1.07137e+000 A 4= 5.95540e-005 A 6=-1.59697e-007 A 8= 1.46894e-010 Side 6 K = 3.15076e+000 A 4= 6.00822e-005 A 6=-1.25125e-007 A 8=-9.05637e-010 A10= 3.54713e-012 Page 27 K = 0.00000e+000 A 4= 3.81421e-005 A 6= 6.96414e-008 A 8=-6.50446e-010 A10= 8.82367e-014 Various data Zoom ratio 1.87 Wide-angle, Medium, Telephoto Focal length 10.50 14.59 19.69 F-number 4.12 4.12 4.12 Half-angle (degrees): 61.70, 55.21, 47.70 Image height 19.50 21.00 21.64 Lens length: 123.70, 120.84, 123.60 BF 13.00 13.00 13.00 d10 19.92 9.22 2.25 d11 1.30 1.74 1.92 d17 3.29 2.85 2.67 d27 8.15 15.99 25.72 Zoom lens group data Group starting plane focal length 1 1 -16.00 2 12 54.80 3 18 51.87 4 28 118.87 Single lens data Lens starting plane, focal length 1 1 -40.33 2 3 -31.17 3 5 -39.54 4 7 26.16 5 9 -60.45 6 12 -32.58 7 13 17 16 8 15 -11.39 9 16 13.03 10 18 -56.11 11 19 16.29 12 21 -27.08 13 23 -37.24 14 24 18.45 15 26 -38.71 16 28 118.87 The following table shows various values ​​for each example.

[0088] [Table 1]

[0089] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of the present invention will be described with reference to Figure 9. In Figure 9, 10 is the camera body, and 11 is a lens device including one of the zoom lenses L0 described in Examples 1 to 4.

[0090] 12 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body and receives the optical image formed by the lens device 11 and converts it into photoelectric energy. The camera body 10 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0091] Thus, by applying the zoom lens L0 of the present invention to an imaging device such as a digital still camera, it is possible to obtain a compact and wide-angle lens while maintaining high optical performance over a wide zoom range.

[0092] Although 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 its gist. [Explanation of Symbols]

[0093] L0 Zoom Lens L1 First lens group Lm intermediate group Ln lens element Ln SP aperture diaphragm

Claims

1. A zoom lens composed of a first lens group with negative refractive power, an intermediate group consisting of a second lens group with positive refractive power, and a final lens group with positive refractive power, arranged sequentially from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming. The zoom lens has an aperture diaphragm, The first lens group comprises a first negative lens, a second negative lens, and a third negative lens arranged in sequence from the object side to the image side. The number of negative lenses included in the first lens group is four or less. The intermediate group comprises a plurality of cemented lenses having a bonding surface that is convex toward the object, and a lens element Ln that is positioned furthest toward the image among the negative refractive power lens elements included in the intermediate group. When the focal length of the first lens group is f1, the focal length of the zoom lens at the wide-angle end is fw, the distance along the optical axis from the lens surface closest to the object of the zoom lens at the wide-angle end to the aperture diaphragm is L1s, the distance along the optical axis from the aperture diaphragm at the wide-angle end to the lens surface closest to the image of the lens element Ln is Lsn, the focal length of the lens element Ln is fn, and the Abbe number of the lens L1n with the largest Abbe number for the d line among the negative lens materials included in the first lens group is νd1n, 1.2<|f1| / fw<2.0 0.5<L1s / Lsn<1.8 0.7<|fn| / Lsn<2.0 80.0<νd1n<100.0 A zoom lens characterized by satisfying the following conditional equation.

2. The first lens group has a negative lens L11 that is positioned closest to the object. When the focal length of the intermediate group at the wide-angle end is fmw and the focal length of the negative lens L11 is f11, 2.0<fmw / fw<3.6 The zoom lens according to claim 1, characterized in that it satisfies the following condition.

3. The first lens group includes a negative lens L11 positioned closest to the object and a negative lens L12 positioned adjacent to the image side of the negative lens L11. When the focal length of the negative lens L11 is f11 and the focal length of the negative lens L12 is f12, 0.70<f11 / f12<2.00 A zoom lens according to claim 1 or 2, characterized in that it satisfies the following conditional expression.

4. When skn is the distance along the optical axis from the image-side lens surface of the aforementioned lens element Ln to the image plane, 1.0<|fn| / skn<3.0 A zoom lens according to any one of claims 1 to 3, characterized in that it satisfies the following conditional expression.

5. When the focal length of the final lens group is fL, 1.0<fL / |fn|<5.0 A zoom lens according to any one of claims 1 to 4, characterized in that it satisfies the following conditional expression.

6. When the focal length of the negative lens L1n, which has the largest Abbe number for the d-line among the negative lenses included in the first lens group, is denoted as f1n, 1.5<f1n / f1<3.0 A zoom lens according to any one of claims 1 to 5, characterized in that it satisfies the following conditional expression.

7. Among the cemented lenses included in the aforementioned intermediate group, the cemented lens Lmc, which is positioned on the image side and has a cemented surface with a convex side facing the object, includes a positive lens and a negative lens. When the Abbe number of the negative lens included in the cemented lens Lmc with respect to the d line is νdmn, and the Abbe number of the positive lens included in the cemented lens Lmc with respect to the d line is νdmp, 35.0<νdmp−νdmn<70.0 A zoom lens according to any one of claims 1 to 6, characterized in that it satisfies the following conditional expression.

8. The zoom lens according to any one of claims 1 to 7, characterized in that when zooming from the wide-angle end to the telephoto end, the first lens group moves toward the image side and then moves toward the object side.

9. A zoom lens comprising a first lens group with negative refractive power, an intermediate group consisting of one or more lens groups, and a final lens group with positive refractive power, arranged in order from the object side to the image side, wherein the spacing between adjacent lens groups changes during zooming, The zoom lens has an aperture diaphragm, The first lens group comprises a first negative lens, a second negative lens, and a third negative lens arranged in sequence from the object side to the image side. The number of negative lenses included in the first lens group is four or less. The aforementioned intermediate group consists of a second lens group with positive refractive power and a third lens group with positive refractive power, arranged in order from the object side to the image side. The intermediate group comprises a plurality of cemented lenses having a bonding surface that is convex toward the object, and a lens element Ln that is positioned furthest toward the image among the negative refractive power lens elements included in the intermediate group. When the focal length of the first lens group is f1, the focal length of the zoom lens at the wide-angle end is fw, the distance along the optical axis from the lens surface closest to the object of the zoom lens at the wide-angle end to the aperture diaphragm is L1s, the distance along the optical axis from the aperture diaphragm at the wide-angle end to the lens surface closest to the image of the lens element Ln is Lsn, the focal length of the lens element Ln is fn, and the Abbe number of the lens L1n with the largest Abbe number for the d line among the negative lens materials included in the first lens group is νd1n, 1.2<|f1| / fw<2.0 0.5<L1s / Lsn<1.8 0.7<|fn| / Lsn<2.0 80.0<νd1n<100.0 A zoom lens characterized by satisfying the following conditional equation.

10. An imaging device characterized by having a zoom lens according to any one of claims 1 to 9 and an image sensor that receives an image formed by the zoom lens.

Images