Zoom lens, extender, and image pickup apparatus

Abstract

To provide a zoom lens capable of easily changing a focal distance range to a long focal distance side by an extender, having a large diameter capable of excellently maintaining optical performance before and after the extender is inserted, and having a long focal distance.SOLUTION: A zoom lens consists of, in order from an object side, first and second lens groups having positive and negative refractive power and a rear group including a plurality of lens groups. The distance between adjacent lens groups is changed during zooming. The rear group includes an aperture diaphragm, an n-th lens group closest to an image and having positive refractive power, and a (n-1)-th lens group on the object side of the n-th lens group and having negative refractive power. Focal distances of the (n-1)-th and the n-th lens groups, and a distance on an optical axis from the surface closest to the image of the (n-1)-th lens group to the surface closest to the object side of the n-th lens group and a distance on the optical axis from the aperture diaphragm to the surface of the image in a zoom position where a distance on the optical axis from a surface closest to the image of the (n-1)-th lens group to a surface closest to the object side of the n-th lens group becomes the shortest in an entire zoom range are set respectively and appropriately.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, there has been a demand for large-aperture zoom lenses with long focal lengths and small F-numbers.

[0003] Another known method is to change the focal length of an optical system by inserting an extender (magnification conversion group) separate from the main optical system. For example, a zoom lens has been proposed in which the focal length range changes to the long focal length side without changing the overall lens length (the distance from the lens surface closest to the object to the image plane) by inserting an extender into the optical path (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-186179 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-238827 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] However, because a large air gap is required to insert the extender into the optical path, if the extender is inserted at an inappropriate position, the main optical system and the extender will become larger. Furthermore, in order to maintain good optical performance before and after inserting the extender, the refractive powers of the lens groups before and after the extender must be set appropriately.

[0006] An object of the present invention is to provide a large-aperture, long-focal-length zoom lens whose focal length range can be easily changed toward the long-focal-length side by inserting an extender into the main optical system, and which can maintain good optical performance before and after inserting the extender. [Means for solving the problem]

[0007] According to one aspect of the present invention, a zoom lens includes, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear group including a plurality of lens groups, and the distance between adjacent lens groups changes during zooming. The rear group includes an aperture stop, an n-th lens group having positive refractive power and arranged closest to the image side, an n-1-th lens group having negative refractive power and arranged adjacent to the n-th lens group on the object side, and an n-2-th lens group having positive refractive power and arranged adjacent to the n-1-th lens group on the object side. The focal length of the n-1-th lens group is fn-1, the focal length of the n-th lens group is fn, the distance on the optical axis from the lens surface closest to the image side of the n-1-th lens group to the lens surface closest to the object side of the n-th lens group at a zoom position where the distance on the optical axis from the lens surface closest to the image side of the n-1-th lens group to the lens surface closest to the object side of the n-th lens group is shortest over the entire zoom range, and the aperture at the zoom position is When the distance on the optical axis from the aperture to the image plane is Lsi, -0.6 <fn-1 / fn≦-0.409 0.3 <Lnm / Lsi<0.7 The present invention is characterized in that the following conditional expression is satisfied: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a large-aperture, long-focal-length zoom lens whose focal length range can be easily changed toward the long-focal-length side by inserting an extender into the main optical system, and which can maintain good optical performance before and after inserting the extender. [Brief explanation of the drawings]

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

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

[0011] 1, 3, 5, 7, 9, and 11 are cross-sectional views of the zoom lenses at the wide-angle end of Examples 1 to 6. The zoom lenses of each Example are used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, cameras for silver halide film, and surveillance cameras.

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

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

[0014] Furthermore, SP is an aperture stop. IP is an image plane, and when the zoom lens of each embodiment is used as the photographic optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed thereon. When the optical system of each embodiment is used as the photographic optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is disposed on the image plane IP.

[0015] In the zoom lens of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group moves as shown by the solid arrows, and when focusing from an object at infinity to a close object, each lens group moves as shown by the dotted arrows.

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

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

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

[0019] The rear group includes an aperture stop SP, an nth lens group having positive refractive power arranged closest to the image side, and an (n-1)th lens group having negative refractive power arranged adjacent to the nth lens group on the object side.

[0020] In the zoom lens of each embodiment, an extender (magnification conversion group) is detachably attached to the zoom lens between the nth lens group, where the axial light beam converges, and the (n-1)th lens group, which is arranged adjacent to the nth lens group on the object side, to convert the magnification of the zoom lens. This configuration allows the extender to be made compact. The extender does not necessarily have to be configured integrally with the lens apparatus having the zoom lens of each embodiment; an extender configured separately from the lens apparatus may be attached to the lens apparatus. In other words, the zoom lens of each embodiment can be used without using an extender.

[0021] Since the nth lens group is located near the image plane, it has positive refractive power to ensure telecentricity on the image side. If the nth lens group had positive refractive power and the (n-1)th lens group had positive refractive power, the overall lens length would be too long to achieve a long focal length on the telephoto side, making it difficult to make the zoom lens compact, so the (n-1)th lens group has negative refractive power. Note that the overall lens length is the distance on the optical axis from the lens surface closest to the object to the image plane.

[0022] The zoom lens of each embodiment satisfies the following conditional expressions (1) and (2).

[0023] -0.7 <fn-1 / fn<-0.1 (1) 0.3 <Lnm / Lsi<0.7 (2) Here, fn-1 is the focal length of the n-1th lens group. fn is the focal length of the nth lens group. Lnm is the distance on the optical axis from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object at zoom position Zm. Lsi is the distance on the optical axis from the aperture stop SP to the image plane at zoom position Zm. Zoom position Zm is the zoom position where the distance on the optical axis from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object is the shortest over the entire zoom range.

[0024] Conditional expression (1) defines the relationship between the focal length of the n-1th lens group and the focal length of the nth lens group. By satisfying conditional expression (1), it is possible to ensure an air gap between the nth lens group and the n-1th lens group for inserting an extender, while achieving a compact zoom lens and good aberration correction. If the upper limit of conditional expression (1) is exceeded and the focal length of the n-1th lens group becomes short, it becomes difficult to ensure an air gap for inserting an extender and to properly correct off-axis aberrations, which is undesirable. If the focal length of the n-1th lens group becomes long and falls below the lower limit of conditional expression (1), the overall lens length becomes too long, which is undesirable.

[0025] Conditional expression (2) defines the relationship between the axial distance from the lens surface closest to the image in the n-1th lens group to the lens surface closest to the object in the nth lens group at the zoom position Zm and the axial distance from the aperture stop SP to the image plane. Satisfying conditional expression (2) ensures a sufficient air gap for inserting an extender while preventing the zoom lens from becoming too large. If the axial distance from the lens surface closest to the image in the n-1th lens group to the lens surface closest to the object in the nth lens group at the zoom position Zm becomes too long by exceeding the upper limit of conditional expression (2), the zoom lens becomes too large, which is undesirable. If the axial distance from the lens surface closest to the image in the n-1th lens group to the lens surface closest to the object in the nth lens group at the zoom position Zm becomes too short by falling below the lower limit of conditional expression (2), it becomes difficult to insert an extender, which is undesirable.

[0026] With the above-described configuration, the focal length range can be easily changed toward the long focal length side by inserting an extender into the main optical system, and a large-aperture, long-focal-length zoom lens can be realized that can maintain good optical performance before and after inserting the extender.

[0027] It is preferable that the numerical ranges of the conditional expressions (1) and (2) be set to the numerical ranges of the following conditional expressions (1a) and (2a).

[0028] -0.6 <fn-1 / fn<-0.2 (1a) 0.32 <Lnm / Lsi<0.60 (2a) It is more preferable that the numerical ranges of the conditional expressions (1) and (2) be set to the numerical ranges of the following conditional expressions (1b) and (2b).

[0029] -0.5 <fn-1 / fn<-0.3 (1b) 0.35 <Lnm / Lsi<0.50 (2b) Next, the configurations that are preferably satisfied in the zoom lens of each embodiment will be described.

[0030] It is preferable that the (n-1)th lens unit move along a locus that is convex toward the image side during zooming from the wide-angle end to the telephoto end. This configuration makes it possible to maintain a constant central imaging position throughout the entire zoom range while effectively correcting off-axial aberrations such as field curvature.

[0031] It is preferable that the zoom lens of each embodiment satisfies one or more of the following conditional expressions (3) to (6).

[0032] 0.7 <f1 / ft<1.1 (3) 0.88 <Lnw / Lnt<1.10 (4) -0.60 <fnl / fn<-0.15 (5) -1.0 <fnp / fnl<-0.6 (6) Here, f1 is the focal length of the first lens group L1. ft is the focal length of the zoom lens at the telephoto end. Lnw is the distance on the optical axis from the lens surface of the (n-1)th lens group closest to the image to the lens surface of the nth lens group closest to the object at the wide-angle end. Lnt is the distance on the optical axis from the lens surface of the (n-1)th lens group closest to the image to the lens surface of the nth lens group closest to the object at the telephoto end. fnl is the focal length of the lens Lnl located closest to the image in the nth lens group. fnp is the focal length of the lens Lnp with the strongest positive refractive power in the nth lens group.

[0033] Conditional expression (3) defines the relationship between the focal length of the first lens group L1 and the focal length of the zoom lens at the telephoto end. By satisfying conditional expression (3), it is possible to achieve both a compact zoom lens and correct axial chromatic aberration and lateral chromatic aberration at the telephoto end. If the upper limit of conditional expression (3) is exceeded and the focal length of the first lens group L1 becomes long, the overall lens length increases, which is undesirable, resulting in a large zoom lens. If the focal length of the first lens group L1 becomes short and falls below the lower limit of conditional expression (3), it is undesirable, resulting in difficulty in correcting axial chromatic aberration and lateral chromatic aberration at the telephoto end.

[0034] Conditional expression (4) defines the relationship between the axial distance from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object at the wide-angle end and the telephoto end. By satisfying conditional expression (4), it is possible to ensure a sufficient air gap for inserting an extender throughout the entire zoom range while effectively correcting off-axis aberrations such as curvature of field and chromatic aberration of magnification. If the axial distance from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object at the wide-angle end becomes too long, exceeding the upper limit of conditional expression (4), it becomes difficult to correct curvature of field and chromatic aberration of magnification at the wide-angle end, which is undesirable. If the axial distance from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object at the telephoto end becomes too long, it becomes difficult to correct curvature of field and chromatic aberration of magnification at the telephoto end, which is undesirable.

[0035] Conditional expression (5) defines the relationship between the focal length of the lens Lnl arranged closest to the image in the nth lens group and the focal length of the nth lens group. By satisfying conditional expression (5), telecentricity on the image side can be ensured while off-axis aberrations such as distortion on the wide-angle side can be well corrected. If the upper limit of conditional expression (5) is exceeded and the focal length of lens Lnl becomes short, it becomes difficult to ensure telecentricity on the image side, which is undesirable. If the focal length of lens Lnl becomes long and falls below the lower limit of conditional expression (5), it becomes difficult to correct off-axis aberrations such as distortion on the wide-angle side, which is undesirable.

[0036] Conditional expression (6) defines the relationship between the focal length of the lens Lnp in the nth lens group, which has the strongest positive refractive power, and the focal length of the lens Lnl in the nth lens group, which is located closest to the image. By satisfying conditional expression (6), off-axis aberrations such as field curvature and distortion on the telephoto side can be effectively corrected. If the focal length of lens Lnp becomes short beyond the upper limit of conditional expression (6), it becomes difficult to correct off-axis aberrations such as field curvature on the telephoto side, which is undesirable. If the focal length of the lens Lnp becomes long below the lower limit of conditional expression (6), it becomes difficult to correct distortion on the telephoto side, which is not preferable.

[0037] It is preferable that the numerical ranges of the conditional expressions (3) to (6) be set to the numerical ranges of the following conditional expressions (3a) to (6a).

[0038] 0.75 <f1 / ft<1.00 (3a) 0.93 <Lnw / Lnt<1.06 (4a) -0.50 <fnl / fn<-0.18 (5a) -0.95 <fnp / fnl<-0.68 (6a) It is more preferable that the numerical ranges of the conditional expressions (3) to (6) be the numerical ranges of the following conditional expressions (3b) to (6b).

[0039] 0.80 <f1 / ft<0.95 (3b) 0.95 <Lnw / Lnt<1.02 (4b) -0.45 <fnl / fn<-0.23 (5b) -0.90 <fnp / fnl<-0.75 (6b) Next, the zoom lens of each embodiment will be described in detail.

[0040] The zoom lens of the first embodiment is made up of a first lens unit L1 to a fifth lens unit L5, which are arranged in order from the object side to the image side and have positive, negative, positive, negative, and positive refractive powers.

[0041] The zoom lens of the second embodiment is made up of a first lens unit L1 to a sixth lens unit L6, which are arranged in order from the object side to the image side and have positive, negative, negative, positive, negative, positive refractive powers.

[0042] The zoom lens of the third embodiment is made up of a first lens unit L1 to a sixth lens unit L6, which are arranged in order from the object side to the image side and have positive, negative, positive, positive, negative, and positive refractive powers.

[0043] The zoom lens of Example 4 is the zoom lens of Example 1, with an extender Lext having a negative refractive power inserted between the fourth lens unit L4 and the fifth lens unit L5.

[0044] The zoom lens of Example 5 is the zoom lens of Example 2, with an extender Lext having a negative refractive power inserted between the fifth lens unit L5 and the sixth lens unit L6.

[0045] The zoom lens of Example 6 is the zoom lens of Example 3, with an extender Lext having a negative refractive power inserted between the fifth lens unit L5 and the sixth lens unit L6.

[0046] In the zoom lenses of Examples 1, 3, 4, and 6, the first lens unit L1 consists of a cemented lens composed of a negative lens and a positive lens, and a positive lens, arranged in that order from the object side to the image side. In the zoom lenses of Examples 2 and 5, the first lens unit L1 consists of a positive lens and a cemented lens composed of a negative lens and a positive lens, arranged in that order from the object side to the image side. With this configuration, spherical aberration, axial chromatic aberration, and lateral chromatic aberration can be effectively corrected at the telephoto end despite the large aperture.

[0047] The fifth lens group L5 in Examples 1 and 4, and the sixth lens group L6 in Examples 2 and 5, are composed of a positive lens and a negative lens arranged in that order from the object side to the image side. The sixth lens group L6 in Examples 3 and 6 are composed of a positive lens, a negative lens, a positive lens, and a negative lens arranged in that order from the object side to the image side. In this way, in the lens group arranged closest to the image side, the negative lens is arranged closest to the image side, and the positive lens is arranged closer to the object than the negative lens, thereby ensuring telecentricity on the image side over the entire zoom range and effectively correcting field curvature and distortion.

[0048] The extender Lext consists of, arranged in order from the object side to the image side, a positive lens, a first cemented lens consisting of a negative lens, a positive lens, and a negative lens, a second cemented lens consisting of a negative lens, a positive lens, and a negative lens, and a third cemented lens consisting of a positive lens and a negative lens. The first cemented lens has negative refractive power, the second cemented lens has negative refractive power, and the third cemented lens has positive refractive power. This configuration can sufficiently converge the light beam entering the extender from the main optical system, thereby providing sufficient magnification conversion effect while making the extender compact and effectively correcting various aberrations that occur in the extender.

[0049] In the zoom lenses of Examples 1 and 4, during zooming from the wide-angle end to the telephoto end, the first lens group L1, the third lens group L3, and the fifth lens group L5 remain stationary, the second lens group L2 moves toward the object side, and the fourth lens group L4 moves along a locus that is convex toward the image side.

[0050] In the zoom lenses of Examples 2, 3, 5, and 6, during zooming from the wide-angle end to the telephoto end, the first lens group L1, the fourth lens group L4, and the sixth lens group L6 remain stationary, the second lens group L2 moves toward the object side, and the fifth lens group L5 moves along a locus that is convex toward the image side.

[0051] In the zoom lenses of Examples 4, 5, and 6, the extender Lext does not move during zooming from the wide-angle end to the telephoto end.

[0052] During zooming from the wide-angle end to the telephoto end, the fourth lens unit L4 moves along a convex locus in Examples 1 and 4, and the fifth lens unit L5 moves along a convex locus in Examples 2, 3, 5, and 6. This makes it possible to maintain a constant central imaging position throughout the entire zoom range while effectively correcting off-axis aberrations such as field curvature.

[0053] In the zoom lenses of Examples 1 and 4, during focusing from an object at infinity to an object at a close distance, the fourth lens unit L4, which is the focus unit, moves toward the image side.

[0054] In the zoom lenses of Examples 2, 3, 5 and 6, when focusing from an object at infinity to an object at a close distance, the fifth lens unit L5, which is the focus unit, moves toward the image side.

[0055] The fourth lens unit L4 in the zoom lenses of Examples 1 and 4, and the fifth lens unit L5 in Examples 2, 3, 5, and 6 are cemented lenses each composed of a positive lens and a negative lens. This configuration makes it possible to effectively suppress fluctuations in various aberrations that accompany changes in the subject distance while achieving a lightweight focus group.

[0056] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below.

[0057] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and vd represents the Abbe number of the optical element. Note that the Abbe number vd of a certain material is given by the following equation, where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines: νd=(Nd-1) / (NF-NC) It is expressed as:

[0058] In each numerical example, d, focal length (mm), F-number, and half angle of view (degrees) are all values ​​when the zoom lens of each example is focused on an object at infinity. "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final lens surface plus the back focus. "Lens group" is not limited to cases where it is composed of multiple lenses, but also includes cases where it is composed of a single lens.

[0059] [Numerical Example 1] Unit: mm Surface Data Surface number rd nd νd 1 348.214 4.00 1.67300 38.3 2 155.532 14.01 1.43875 94.7 3 -713.399 0.30 4 159.388 11.00 1.43875 94.7 5 6056.224 (variable) 6 85.693 9.59 1.65412 39.7 7 -482.320 0.30 8 1229.057 1.80 1.60342 38.0 9 47.388 10.00 10 -280.812 1.80 1.49700 81.5 11 51.380 7.13 1.91082 35.3 12 194.966 5.57 13 -82.611 1.80 1.72916 54.7 14 293.893 (variable) 15 196.900 6.61 1.49700 81.5 16 -114.138 0.30 17 93.409 4.07 1.49700 81.5 18 252.342 0.30 19 63.068 3.87 1.49700 81.5 20 103.727 6.11 21 -93.470 2.20 1.48749 70.2 22 71.054 5.98 23 (Aperture) ∞ 12.58 24 92.191 8.70 1.59522 67.7 25 -96.989 0.81 26 -314.351 2.00 1.61340 44.3 27 67.755 5.00 28 135.609 1.80 1.85478 24.8 29 55.827 7.22 1.59282 68.6 30 -345.354 0.15 31 76.673 4.86 1.87070 40.7 32 5031.140 (variable) 33 -10122.483 3.34 1.89286 20.4 34 -122.717 1.50 1.67300 38.1 35 59.654 (variable) 36 67.735 8.22 1.63980 34.5 37 -127.121 3.04 38 -141.175 2.00 2.00100 29.1 39 191.628 41.27 Image plane ∞ Various data Zoom ratio 2.85 Wide-angle Mid-range Telephoto Focal length 103.00 192.20 294.00 F-number 2.91 2.91 2.91 Half angle of view (degrees) 11.86 6.42 4.21 Image height 21.64 21.64 21.64 Lens total length 370.00 370.00 370.00 BF 41.27 41.27 41.27 d 5 2.50 59.47 94.39 d14 93.24 36.27 1.35 d32 2.46 6.30 2.00 d35 72.56 68.73 73.03 Zoom lens group data Group starting plane focal length 1 1 270.20 2 6 -83.96 3 15 70.76 4 33 -104.57 5 36 324.38 Single lens data Lens starting surface focal length 1 1 -421.17 2 2 292.48 3 4 372.88 4 6 111.99 5 8 -81.73 6 10 -87.23 7 11 74.82 8 13 -88.26 9 15 146.41 10 17 295.89 11 19 313.81 12 21 -82.45 13 24 80.79 14 26 -90.69 15 28 -112.18 16 29 81.61 17 31 89.38 18 33 139.11 19 34 -59.45 20 36 70.22 21 38 -80.96 [Numerical Example 2] Unit: mm Surface Data Surface number rd nd νd 1 176.924 10.23 1.49700 81.5 2 7195.119 0.50 3 149.004 4.00 1.67300 38.3 4 87.741 15.84 1.43875 94.7 5 824.823 (variable) 6 104.150 8.25 1.65412 39.7 7 -292.447 0.30 8 -409.815 1.80 1.57501 41.5 9 42.899 9.13 10 -512.719 1.80 1.49700 81.5 11 44.775 7.48 1.91082 35.3 12 146.745 (variable) 13 -75.055 1.80 1.72916 54.7 14 -13401.153 (variable) 15 190.237 5.48 1.59282 68.6 16 -168.072 0.30 17 90.590 4.76 1.49700 81.5 18 501.290 3.49 19 -112.677 2.20 1.65160 58.5 20 547.372 4.41 21 (Aperture) ∞ 14.16 22 90.213 7.45 1.59522 67.7 23 -174.714 7.47 24 -357.946 2.00 1.61340 44.3 25 61.677 5.34 26 195.369 1.80 1.85478 24.8 27 62.924 7.38 1.59282 68.6 28 -166.832 0.15 29 71.433 5.02 1.87070 40.7 30 1004.073 (variable) 31 -2872.035 3.64 1.89286 20.4 32 -118.966 1.50 1.67300 38.3 33 58.892 (variable) 34 67.037 9.34 1.67300 38.3 35 -170.544 4.92 36 -209.118 2.00 2.00100 29.1 37 171.944 36.41 Image plane ∞ Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 103.00 179.84 293.00 F-number 2.91 2.91 2.91 Half angle of view (degrees) 11.86 6.86 4.22 Image height 21.64 21.64 21.64 Lens total length 360.00 360.00 360.00 BF 36.41 36.41 36.41 d 5 2.50 47.55 82.95 d12 8.29 7.57 7.00 d14 80.94 36.61 1.78 d30 5.35 9.01 3.00 d33 72.56 68.90 74.91 Zoom lens group data Group starting plane focal length 1 1 243.25 2 6 -279.94 3 13 -103.52 4 15 70.73 5 31 -101.21 6 34 221.00 Single lens data Lens starting surface focal length 1 1 364.78 2 3 -325.65 3 4 222.33 4 6 118.38 5 8 -67.44 6 10 -82.77 7 11 68.36 8 13 -103.52 9 15 151.39 10 17 221.63 11 19 -143.22 12 22 101.01 13 24 -85.62 14 26 -109.27 15 27 78.01 16 29 88.10 17 31 138.91 18 32 -58.33 19 34 72.65 20 36 -94.02 [Numerical Example 3] Unit: mm Surface Data Surface number rd nd νd 1 337.251 3.50 1.72047 34.7 2 158.275 13.75 1.49700 81.5 3 -1027.574 0.30 4 163.884 11.30 1.43875 94.7 5 7458.212 (variable) 6 323.613 5.43 1.67270 32.1 7 -255.837 6.16 8 -195.213 1.80 1.51742 52.4 9 57.043 7.51 10 -472.171 1.80 1.49700 81.5 11 60.524 6.58 1.88300 40.8 12 228.247 5.21 13 -97.594 1.80 1.75500 52.3 14 -557.632 (variable) 15 150.469 5.98 1.49700 81.5 16 -278.413 0.30 17 93.334 5.65 1.49700 81.5 18 843.516 0.30 19 63.911 5.81 1.49700 81.5 20 132.786 9.28 21 -168.942 2.20 1.53172 48.8 22 52.656 (variable) 23 (Aperture) ∞ 0.95 24 58.788 9.10 1.59522 67.7 25 -154.429 0.86 26 278.909 2.00 1.73800 32.3 27 48.964 5.05 28 162.568 1.80 1.72047 34.7 29 76.835 5.38 1.59282 68.6 30 -457.240 0.15 31 64.282 4.70 1.88300 40.8 32 348.254 (variable) 33 -448.660 3.65 2.00069 25.5 34 -82.017 1.50 1.76385 48.5 35 59.367 (variable) 36 61.553 7.13 1.49700 81.5 37 834.029 0.30 38 64.536 2.00 1.77250 49.6 39 38.148 0.70 40 39.655 11.97 1.60342 38.0 41 -175.599 0.20 42 -198.622 2.00 1.71736 29.5 43 63.810 25.00 Image plane ∞ Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 103.00 192.05 293.00 F-number 2.91 2.92 2.91 Half angle of view (degrees) 11.86 6.43 4.22 Image height 21.64 21.64 21.64 Lens total length 370.00 370.00 370.00 BF 25.00 25.00 25.00 d 5 2.00 59.04 94.00 d14 95.20 36.92 1.20 d22 8.15 9.39 10.15 d32 3.00 6.63 3.00 d35 82.56 78.93 82.56 Zoom lens group data Group starting plane focal length 1 1 263.22 2 6 -84.75 3 15 246.73 4 23 62.39 5 33 -81.68 6 36 199.72 Single lens data Lens starting surface focal length 1 1 -417.38 2 2 277.02 3 4 381.74 4 6 213.20 5 8 -85.11 6 10 -107.82 7 11 91.59 8 13 -156.95 9 15 197.45 10 17 210.63 11 19 241.16 12 21 -75.24 13 24 72.69 14 26 -80.77 15 28 -204.02 16 29 111.38 17 31 88.59 18 33 99.80 19 34 -44.88 20 36 133.31 21 38 -124.90 22 40 54.76 23 42 -67.11 [Numerical Example 4] Unit: mm Surface Data Surface number rd nd νd 1 348.214 4.00 1.67300 38.3 2 155.532 14.01 1.43875 94.7 3 -713.399 0.30 4 159.388 11.00 1.43875 94.7 5 6056.224 (variable) 6 85.693 9.59 1.65412 39.7 7 -482.320 0.30 8 1229.057 1.80 1.60342 38.0 9 47.388 10.00 10 -280.812 1.80 1.49700 81.5 11 51.380 7.13 1.91082 35.3 12 194.966 5.57 13 -82.611 1.80 1.72916 54.7 14 293.893 (variable) 15 196.900 6.61 1.49700 81.5 16 -114.138 0.30 17 93.409 4.07 1.49700 81.5 18 252.342 0.30 19 63.068 3.87 1.49700 81.5 20 103.727 6.11 21 -93.470 2.20 1.48749 70.2 22 71.054 5.98 23 (Aperture) ∞ 12.58 24 92.191 8.70 1.59522 67.7 25 -96.989 0.81 26 -314.351 2.00 1.61340 44.3 27 67.755 5.00 28 135.609 1.80 1.85478 24.8 29 55.827 7.22 1.59282 68.6 30 -345.354 0.15 31 76.673 4.86 1.87070 40.7 32 5031.140 (variable) 33 -10122.483 3.34 1.89286 20.4 34 -122.717 1.50 1.67300 38.1 35 59.654 (variable) 36 25.645 6.36 1.59282 68.6 37 155.139 0.20 38 50.156 1.20 1.77250 49.6 39 18.293 7.19 1.66680 33.0 40 1574.067 1.20 2.00100 29.1 41 32.730 4.66 42 149.830 1.10 2.00100 29.1 43 16.142 12.22 1.72047 34.7 44 -16.651 1.00 1.76385 48.5 45 42.035 1.00 46 34.733 9.67 1.59551 39.2 47 -21.544 1.20 1.76385 48.5 48 -545.234 3.00 49 67.735 8.22 1.63980 34.5 50 -127.121 3.04 51 -141.175 2.00 2.00100 29.1 52 191.628 41.27 Image plane ∞ Various data Zoom ratio 2.85 Wide-angle Mid-range Telephoto Focal length 143.99 268.68 411.00 F-number 4.10 4.10 4.10 Half angle of view (degrees) 8.54 4.60 3.01 Image height 21.64 21.64 21.64 Lens total length 370.00 370.00 370.00 BF 41.27 41.27 41.27 d 5 2.50 59.47 94.39 d14 93.24 36.27 1.35 d32 2.46 6.30 2.00 d35 22.56 18.73 23.03 Zoom lens group data Group starting plane focal length 1 1 270.20 2 6 -83.96 3 15 70.76 4 33 -104.57 EXT 36 -114.28 5 50 324.38 [Numerical Example 5] Unit: mm Surface Data Surface number rd nd νd 1 176.924 10.23 1.49700 81.5 2 7195.119 0.50 3 149.004 4.00 1.67300 38.3 4 87.741 15.84 1.43875 94.7 5 824.823 (variable) 6 104.150 8.25 1.65412 39.7 7 -292.447 0.30 8 -409.815 1.80 1.57501 41.5 9 42.899 9.13 10 -512.719 1.80 1.49700 81.5 11 44.775 7.48 1.91082 35.3 12 146.745 (variable) 13 -75.055 1.80 1.72916 54.7 14 -13401.153 (variable) 15 190.237 5.48 1.59282 68.6 16 -168.072 0.30 17 90.590 4.76 1.49700 81.5 18 501.290 3.49 19 -112.677 2.20 1.65160 58.5 20 547.372 4.41 21 (Aperture) ∞ 14.16 22 90.213 7.45 1.59522 67.7 23 -174.714 7.47 24 -357.946 2.00 1.61340 44.3 25 61.677 5.34 26 195.369 1.80 1.85478 24.8 27 62.924 7.38 1.59282 68.6 28 -166.832 0.15 29 71.433 5.02 1.87070 40.7 30 1004.073 (variable) 31 -2872.035 3.64 1.89286 20.4 32 -118.966 1.50 1.67300 38.3 33 58.892 (variable) 34 24.066 6.51 1.53775 74.7 35 224.864 0.20 36 44.663 1.20 1.80400 46.5 37 19.939 5.99 1.66680 33.0 38 186.989 1.20 1.91082 35.3 39 34.880 3.18 40 549.501 1.10 2.00100 29.1 41 15.135 11.47 1.72047 34.7 42 -16.271 1.00 1.76385 48.5 43 33.659 1.04 44 32.473 9.45 1.59551 39.2 45 -20.737 1.20 1.76385 48.5 46 -238.845 5.96 47 67.037 9.34 1.67300 38.3 48 -170.544 4.92 49 -209.118 2.00 2.00100 29.1 50 171.944 36.41 Image plane ∞ Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 144.48 252.27 411.00 F-number 4.10 4.10 4.10 Half angle of view (degrees) 8.52 4.90 3.01 Image height 21.64 21.64 21.64 Lens total length 360.00 360.00 360.00 BF 36.41 36.41 36.41 d 5 2.50 47.55 82.95 d12 8.29 7.57 7.00 d14 80.94 36.61 1.78 d30 5.35 9.01 3.00 d33 23.06 19.40 25.41 Zoom lens group data Group starting plane focal length 1 1 243.25 2 6 -279.94 3 13 -103.52 4 15 70.73 5 31 -101.21 EXT 34 -122.25 6 47 221.00 [Numerical Example 6] Unit: mm Surface Data Surface number rd nd νd 1 337.251 3.50 1.72047 34.7 2 158.275 13.75 1.49700 81.5 3 -1027.574 0.30 4 163.884 11.30 1.43875 94.7 5 7458.212 (variable) 6 323.613 5.43 1.67270 32.1 7 -255.837 6.16 8 -195.213 1.80 1.51742 52.4 9 57.043 7.51 10 -472.171 1.80 1.49700 81.5 11 60.524 6.58 1.88300 40.8 12 228.247 5.21 13 -97.594 1.80 1.75500 52.3 14 -557.632 (variable) 15 150.469 5.98 1.49700 81.5 16 -278.413 0.30 17 93.334 5.65 1.49700 81.5 18 843.516 0.30 19 63.911 5.81 1.49700 81.5 20 132.786 9.28 21 -168.942 2.20 1.53172 48.8 22 52.656 (variable) 23 (Aperture) ∞ 0.95 24 58.788 9.10 1.59522 67.7 25 -154.429 0.86 26 278.909 2.00 1.73800 32.3 27 48.964 5.05 28 162.568 1.80 1.72047 34.7 29 76.835 5.38 1.59282 68.6 30 -457.240 0.15 31 64.282 4.70 1.88300 40.8 32 348.254 (variable) 33 -448.660 3.65 2.00069 25.5 34 -82.017 1.50 1.76385 48.5 35 59.367 (variable) 36 25.121 6.63 1.59282 68.6 37 340.091 0.20 38 72.638 1.20 1.72916 54.7 39 24.635 6.32 1.76182 26.5 40 -223.259 1.20 2.05090 26.9 41 29.346 5.98 42 131.476 1.10 2.05090 26.9 43 16.890 11.78 1.72047 34.7 44 -14.662 1.00 1.76385 48.5 45 69.410 1.00 46 36.310 8.87 1.59551 39.2 47 -21.335 1.20 1.76385 48.5 48 609.160 12.00 49 61.553 7.13 1.49700 81.5 50 834.029 0.30 51 64.536 2.00 1.77250 49.6 52 38.148 0.70 53 39.655 11.97 1.60342 38.0 54 -175.599 0.20 55 -198.622 2.00 1.71736 29.5 56 63.810 25.00 Image plane ∞ Various data Zoom ratio 2.84 Wide-angle Mid-range Telephoto Focal length 144.48 269.40 411.00 F-number 4.10 4.10 4.10 Half angle of view (degrees) 8.52 4.59 3.01 Image height 21.64 21.64 21.64 Lens total length 370.00 370.00 370.00 BF 25.00 25.00 25.00 d 5 2.00 59.04 94.00 d14 95.20 36.92 1.20 d22 8.15 9.39 10.15 d32 3.00 6.63 3.00 d35 24.09 20.46 24.09 Zoom lens group data Group starting plane focal length 1 1 263.22 2 6 -84.75 3 15 246.73 4 23 62.39 5 33 -81.68 EXT 36 -118.58 7 49 199.72 The various values ​​in each numerical example are summarized in Table 1 below.

[0060] [Table 1]

[0061] [Imaging device] Next, an embodiment of a digital still camera (imaging device) using the zoom lens of each embodiment as an imaging optical system will be described with reference to Fig. 13. In Fig. 13, 10 denotes a camera body, and 11 denotes an imaging optical system constituted by any of the zoom lenses described in Embodiments 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 the imaging optical system 11. The camera body 10 may be a so-called single-lens reflex camera having a quick-turn mirror, or a so-called mirrorless camera having no quick-turn mirror.

[0062] In this way, by applying the zoom lens of each embodiment to an imaging device such as a digital still camera, an imaging device with a small lens can be obtained. [Explanation of symbols]

[0063] L1 First lens group L2 Second lens group

Claims

1. A zoom lens comprising, arranged in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group including a plurality of lens groups, wherein the spacing between adjacent lens groups changes during zooming, the rear group comprises an aperture stop, an n-th lens group having positive refractive power and arranged closest to the image side, an (n-1)-th lens group having negative refractive power and arranged adjacent to the n-th lens group on the object side, and an (n-2)-th lens group having positive refractive power and arranged adjacent to the n-1-th lens group on the object side, Let fn-1 be the focal length of the n-1th lens group, fn be the focal length of the nth lens group, Lnm be the distance on the optical axis from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object at a zoom position where the distance on the optical axis from the lens surface of the n-1th lens group closest to the image to the lens surface of the nth lens group closest to the object is the shortest over the entire zoom range, and Lsi be the distance on the optical axis from the aperture stop to the image plane at that zoom position. -0.6<fn-1 / fn≦-0.409 0.3<Lnm / Lsi<0.7 A zoom lens characterized by satisfying the following conditional expressions:

2. When the focal length of the first lens group is f1 and the focal length of the zoom lens at the telephoto end is ft, 0.7<f1 / ft<1.1 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. Let Lnw be the distance on the optical axis from the lens surface closest to the image in the (n-1)th lens group to the lens surface closest to the object in the nth lens group at the wide-angle end, and Lnt be the distance on the optical axis from the lens surface closest to the image in the (n-1)th lens group to the lens surface closest to the object in the nth lens group at the telephoto end, 0.88<Lnw / Lnt<1.10 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. 4. The zoom lens according to claim 1, wherein the (n-1)th lens group moves during focusing.

5. 5. The zoom lens according to claim 4, wherein the (n-1)th lens group is made up of a cemented lens composed of a positive lens and a negative lens.

6. When the focal length of the lens arranged closest to the image side in the nth lens group is fnl, -0.60<fnl / fn<-0.15 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. When the focal length of the lens in the nth lens group arranged closest to the image side is defined as fnl, and the focal length of the lens in the nth lens group having the strongest positive refractive power is defined as fnp, -1.0<fnp / fnl<-0.6 7. The zoom lens according to claim 1, wherein the following condition is satisfied:

8. further comprising an extender between the (n-1)th lens group and the nth lens group for converting the magnification of the zoom lens; 8. The zoom lens according to claim 1, wherein when the extender is inserted into the optical path, the focal length range of the zoom lens changes to the long focal length side without changing the overall lens length.

9. The zoom lens according to any one of claims 1 to 8, wherein the rear group comprises the aperture stop, and lens groups arranged in order from the object side to the image side: a third lens group having positive refractive power as the (n-2)-th lens group, a fourth lens group having negative refractive power as the (n-1)-th lens group, and a fifth lens group having positive refractive power as the n-th lens group.

10. 9. The zoom lens according to claim 1, wherein the rear group comprises the aperture stop, and, as lens groups arranged in this order from the object side to the image side, a third lens group having negative refractive power, a fourth lens group having positive refractive power as the (n-2)th lens group, a fifth lens group having negative refractive power as the (n-1)th lens group, and a sixth lens group having positive refractive power as the nth lens group.

11. 9. The zoom lens according to claim 1, wherein the rear group comprises the aperture stop, and lens groups arranged in this order from the object side to the image side: a third lens group having positive refractive power, a fourth lens group having positive refractive power as the (n-2)th lens group, a fifth lens group having negative refractive power as the (n-1)th lens group, and a sixth lens group having positive refractive power as the nth lens group.

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

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

14. 14. The zoom lens according to claim 1, wherein the nth lens group comprises a positive lens and a negative lens arranged in this order from the object side to the image side.

15. 14. The zoom lens according to claim 1, wherein the nth lens group consists of a positive lens, a negative lens, a positive lens, and a negative lens arranged in this order from the object side to the image side.

16. 16. An extender that is detachably attached to the zoom lens according to claim 1 and converts the magnification of the zoom lens, comprising: the extender is detachably attached between the (n-1)th lens group and the nth lens group, An extender comprising, arranged in order from the object side to the image side, a positive lens, a first cemented lens having negative refractive power and composed of a negative lens, a positive lens, and a negative lens, a second cemented lens having negative refractive power and composed of a negative lens, a positive lens, and a negative lens, and a third cemented lens having positive refractive power and composed of a positive lens and a negative lens.

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

Images