Zoom lens and imaging apparatus having the same

Abstract

To provide a small and lightweight zoom lens which has high optical performance over the entire zoom range.SOLUTION: A zoom lens (1a) has a first lens group (L1) of positive refractive power, a second lens group (L2) of negative refractive power, a third lens group (L3) of positive refractive power, a fourth lens group (L4) of the positive refractive power, and a fifth lens group of the negative refractive power that are arranged from an object side to an image side, and a gap between adjacent lens groups changes when zooming from a wide angle end to a telephoto end. In zooming from the wide angle end to the telephoto end, the gap between the first lens group and the second lens group widens, a gap between the second lens group and the third lens group narrows, and a gap between the third lens group and the fourth lens group narrows. The third lens group comprises a positive lens and a negative lens arranged from the object side to the image side in order. An entire optical length TLt of the zoom lens at the telephoto end, a focus distance ft of the zoom lens at the telephoto end, and a focus distance f3 of the third lens group satisfy a prescribed conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical system, and more particularly to a zoom lens for use in a silver halide film camera, a digital still camera, a video camera, a digital video camera, or the like, and an imaging device having the same. [Background technology]

[0002] In recent years, imaging devices such as digital cameras and video cameras have adopted high-pixel imaging elements. The optical systems used in such imaging devices are required to have excellent correction of various aberrations, high optical performance across the entire screen, and to be small and lightweight.

[0003] Patent Document 1 discloses a zoom lens having a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, and a sixth lens group with positive refractive power. In this zoom lens, the third lens group is composed of two lenses: a positive lens and a negative meniscus lens convex toward the image side.

[0004] Patent Document 2 discloses a zoom lens having a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power. In this zoom lens, the third lens group is composed of two lenses: a positive lens and a negative meniscus lens convex toward the object side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-209347 A [Patent Document 2] JP 2013-97322 A Summary of the Invention [Problem to be solved by the invention]

[0006] In general, to make a zoom lens compact, it is effective to adopt a telephoto type power arrangement at the telephoto end and to strengthen the positive refractive power on the object side and the negative refractive power on the image side. However, if the refractive power of each lens group is strengthened, the fluctuation of various aberrations accompanying zooming becomes large, and it becomes difficult to satisfactorily correct various aberrations with a small number of lenses. For this reason, in order to achieve both a compact and lightweight optical system, it is important to appropriately set the refractive power and lens configuration of each lens group.

[0007] However, in the zoom lenses disclosed in Patent Documents 1 and 2, the refractive power and lens configuration of the third lens group are inappropriate, making it difficult to realize a small and lightweight zoom lens.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a small, lightweight zoom lens and an image pickup apparatus that have high optical performance over the entire zoom range. [Means for solving the problem]

[0009] A zoom lens according to one aspect of the present invention has, arranged 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, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein the distance between adjacent lens groups changes when zooming from the wide-angle end to the telephoto end, and during zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the distance between the third lens group and the fourth lens group decreases, a lens in the first lens group arranged closest to the object has positive refractive power, and the third lens group is composed of a positive lens and a negative lens arranged in order from the object side to the image side, and a total optical length TLt of the zoom lens at the telephoto end, a focal length ft of the zoom lens at the telephoto end, and a focal length f3 of the third lens group satisfy predetermined conditional expressions.

[0010] Other objects and features of the present invention are illustrated in the following examples. Effect of the Invention

[0011] According to the present invention, it is possible to provide a small, lightweight zoom lens and an imaging device that have high optical performance over the entire zoom range. [Brief description of the drawings]

[0012] [Figure 1] 1A and 1B are cross-sectional views of a zoom lens according to a first embodiment at a wide-angle end and a telephoto end. [Diagram 2] 4A to 4C are longitudinal aberration diagrams of the zoom lens in Example 1 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Diagram 3] 11A and 11B are cross-sectional views of a zoom lens according to a second embodiment at a wide-angle end and a telephoto end. [Figure 4] 10A to 10C are longitudinal aberration diagrams of the zoom lens in Example 2 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Diagram 5] 11A and 11B are cross-sectional views of a zoom lens at a wide-angle end and a telephoto end in a third embodiment. [Figure 6] 11A to 11C are longitudinal aberration diagrams of the zoom lens in Example 3 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Figure 7] 11A and 11B are cross-sectional views of a zoom lens at a wide-angle end and a telephoto end in a fourth embodiment. [Figure 8] 13A to 13C are longitudinal aberration diagrams of the zoom lens in Example 4 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Figure 9] 13A to 13C are cross-sectional views of a zoom lens at a wide-angle end and a telephoto end in a fifth embodiment. [Figure 10] 13A to 13C are longitudinal aberration diagrams of the zoom lens in Example 5 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Figure 11] 13A to 13C are cross-sectional views of a zoom lens according to a sixth embodiment at a wide-angle end and a telephoto end. [Figure 12] 13A to 13C are longitudinal aberration diagrams of the zoom lens in Example 6 at the wide-angle end, at a middle zoom position, and at the telephoto end. [Figure 13]FIG. 4 is a diagram showing the relationship between the Abbe number and the partial dispersion ratio in each example. [Figure 14] 1 is a schematic diagram of an imaging device equipped with a zoom lens in each embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0014] 1, 3, 5, 7, 9, and 11 are cross-sectional views of zoom lenses (optical systems) 1a to 1f of Examples 1 to 6, respectively, when focused on infinity (infinity focused state). The zoom lenses of the respective Examples are imaging optical systems used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide cameras, and surveillance cameras, as well as optical instruments including interchangeable lenses.

[0015] In each 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 composed of multiple lens groups. In each embodiment, a lens group is a group of lenses that move together or are stationary during zooming. In the zoom lens of each embodiment, the interval between adjacent lens groups changes when the lens is zoomed from the wide-angle end to the telephoto end. The wide-angle end and the telephoto end are zoom states when the lens group that moves during zooming is located at both ends of the range in which it can move mechanically in the direction along the optical axis OA (optical axis direction). The lens group may be composed of one lens or multiple lenses. The lens group may also include an aperture stop.

[0016] In each cross-sectional view, i (a natural number) indicates the order counted from the object side, and Li indicates the i-th lens group. SP is an aperture stop. IP is an image plane, and when the zoom lenses 1a to 1f of each embodiment are used as an imaging optical system for a digital video camera or a digital still camera, the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor is disposed on the image plane IP. When the optical systems 1a to 1f of each embodiment are used as an imaging optical system for a silver halide film camera, the photosensitive surface of the film is disposed on the image plane IP. In the zoom lenses 1a to 1f of each embodiment, when zooming from the wide-angle end to the telephoto end, each lens group is moved as shown by the solid arrow in each cross-sectional view.

[0017] 2, 4, 6, 8, 10, and 12 are longitudinal aberration diagrams of the zoom lenses 1a to 1f of Examples 1 to 6, respectively. In each aberration diagram, (A) shows longitudinal aberration diagram at the wide-angle end and focused at infinity, (B) shows longitudinal aberration diagram at the intermediate zoom position and focused at infinity, and (C) shows longitudinal aberration diagram at the telephoto end and focused at infinity.

[0018] In the spherical aberration diagram, Fno is the F-number, and the amount of spherical aberration for the d-line (wavelength 587.6 nm) and g-line (wavelength 435.8 nm) is shown by a solid line and a two-dot chain line, respectively. In the astigmatism diagram, ΔS indicates the amount of astigmatism on the sagittal image plane (solid line), and ΔM indicates the amount of astigmatism on 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. ω is the half angle of view (°).

[0019] Next, the characteristic configuration and conditions of the zoom lens of each embodiment will be described. The zoom lens of each embodiment has a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and one or more lens groups (rear group LR) arranged in order from the object side to the image side. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. With this configuration, when zooming from the wide-angle end to the telephoto end, a telephoto type power arrangement is obtained at the telephoto end, and the total optical length at the telephoto end (the distance from the most object-side surface to the image surface IP) can be reduced. The third lens group L3 is composed of two lenses, a positive lens and a negative lens, arranged in that order from the object side to the image side, so that it is possible to reduce the weight of the third lens group L3 and the entire zoom lens system.

[0020] In each embodiment, in order to obtain a small, lightweight lens with good optical performance, it is necessary to satisfy the following conditional expressions (1) and (2).

[0021] 0.50 <TLt / ft<0.69 ···(1) 0.10 <f3 / ft<0.58 ···(2) In conditional formula (1), TLt is the total optical length of the entire zoom lens system at the telephoto end (the distance from the surface closest to the object to the image plane IP), and ft is the focal length of the entire zoom lens system at the telephoto end. In conditional formula (2), f3 is the focal length of the third lens unit L3.

[0022] Conditional formula (1) indicates the ratio (telephoto ratio) between the total optical length and focal length of the zoom lens at the telephoto end. Conditional formula (1) is a conditional formula for appropriately achieving a small, lightweight zoom lens and good optical performance. If the upper limit of conditional formula (1) is exceeded and the refractive power of the first lens group L1 becomes weak, the zoom lens becomes large. On the other hand, if the lower limit of conditional formula (1) is exceeded and the refractive power of the first lens group L1 becomes strong, chromatic aberration becomes noticeable at the telephoto end, making it difficult to maintain optical performance.

[0023] Preferably, the numerical range of conditional expression (1) is set as in the following conditional expression (1a).

[0024] 0.55 <TLt / ft<0.69 ···(1a) Conditional formula (2) indicates the ratio between the focal length of the third lens group L3 and the focal length of the zoom lens at the telephoto end. Conditional formula (2) is a conditional formula for appropriately suppressing the refractive index of the third lens group L3. If the upper limit of conditional formula (2) is exceeded and the refractive power of the third lens group L3 becomes weak, the zoom lens becomes large. On the other hand, if the lower limit of conditional formula (2) is exceeded and the refractive power of the third lens group L3 becomes strong, spherical aberration becomes large at the wide-angle end, making it difficult to maintain optical performance.

[0025] Preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2a).

[0026] 0.20 <f3 / ft<0.50 ···(2a) According to each embodiment, by being configured so as to satisfy conditional expressions (1) and (2), it is possible to realize a small, lightweight telephoto zoom lens in which optical performance is excellent throughout the entire zoom range.

[0027] In each embodiment, in order to obtain a smaller, lighter, and more favorable optical performance, it is preferable to satisfy the following conditional expression (3).

[0028] 0.25 <D3 / LT3<1.00 ···(3) In conditional formula (3), D3 is the distance between the positive lens and the negative lens in the third lens group L3, and LT3 is the total thickness of the third lens group L3. Conditional formula (3) is a conditional formula for appropriately setting the distance D3 between the positive lens and the negative lens in the third lens group L3. If the upper limit of conditional formula (3) is exceeded, the positive lens and the negative lens in the third lens group L3 cannot be physically arranged. On the other hand, if the lower limit of conditional formula (3) is exceeded, spherical aberration becomes correctable, making it difficult to maintain optical performance with a two-lens configuration.

[0029] It is more preferable that the numerical range of conditional expression (3) is set as in the following conditional expression (3a).

[0030] 0.25 <D3 / LT3<0.90 ···(3a) In each embodiment, in order to obtain a smaller, lighter lens with better optical performance, it is preferable to satisfy the following conditional expression (4) when the Abbe number of the positive lens constituting the third lens unit L3 is νdp.

[0031] νdp>65 (4) Conditional formula (4) indicates a material that has an appropriate Abbe number for the positive lens constituting the third lens group L3. Here, the Abbe number νd of a certain material can be expressed as follows, 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.

[0032] νd=(Nd-1) / (NF-NC) (a) If the lower limit of condition (4) is exceeded, achromatism becomes insufficient, making it difficult to correct chromatic aberration.

[0033] More preferably, the numerical range of conditional expression (4) is set as in the following conditional expression (4a).

[0034] νdp>70 (4a) In each embodiment, in order to obtain a smaller, lighter lens with better optical performance, it is preferable to satisfy the following conditional expression (5), where Ndn is the refractive index at the d-line of the negative lens constituting the third lens unit L3.

[0035] Ndn>1.80 (5) If the lower limit of condition (5) is exceeded, the Petzval sum will take an excessively large value in the negative direction, undesirably increasing off-axis aberrations such as field curvature.

[0036] It is more preferable that the numerical range of conditional expression (5) is set as shown in the following conditional expression (5).

[0037] Ndn>1.85 (5a) In each embodiment, in order to obtain an even smaller, lighter lens with better controlled optical performance, it is preferable to satisfy the following conditional formula (6), where νdn is the Abbe number of the negative lens constituting the third lens unit L3 and θgFn is the partial dispersion ratio.

[0038] 25<νdn<45 (6) θgFn-0.6438+0.001682×νdn<0.02 (7) Here, the partial dispersion ratio θgF of a certain material can be expressed as follows, where the refractive indices of the material for the g-line (435.8 nm), F-line (486.1 nm), and C-line (656.3 nm) are Ng, NF, and NC, respectively.

[0039] θgF=(Ng-NF) / (NF-NC) ···(b) FIG. 13 is a graph showing the relationship between the Abbe number vd and the partial dispersion ratio θgF. In FIG. 13, the horizontal axis shows the Abbe number vd, and the vertical axis shows the partial dispersion ratio θgF. FIG. 13 also shows two products manufactured by Ohara Inc.: PBM2 (vd=36.26, θgF=0.5828) and NSL7 (vd=60.49, θgF=0.5436). The line connecting these two points is the reference line. For low dispersion glass, using glass located above the reference line is effective for correcting secondary spectrum, and the correction effect increases the further away from the reference line.

[0040] Conditional expressions (6) and (7) indicate the material for which the Abbe number νdn and partial dispersion ratio θgF of the negative lens constituting the third lens group L3 are appropriate values. A lens material that has high dispersion but anomalous dispersion is not effective for correcting chromatic aberration. A lens material that satisfies conditional expressions (6) and (7) has high dispersion but suppressed anomalous dispersion, and is therefore effective for correcting chromatic aberration.

[0041] If the upper limit of conditional formula (6) is exceeded, the achromatism is insufficient with a two-lens configuration, making it difficult to correct axial chromatic aberration. On the other hand, if the lower limit of conditional formula (6) is exceeded, the achromatism is correctable with a two-lens configuration, making it difficult to correct axial chromatic aberration. If the upper limit of conditional formula (7) is exceeded, the anomalous dispersion of the material of the negative lens becomes large, making it difficult to correct the secondary spectrum of chromatic aberration with a two-lens configuration.

[0042] More preferably, the numerical ranges of conditional expressions (6) and (7) are set as shown in the following conditional expressions (6a) and (7a), respectively.

[0043] 25<νdn<35 (6a) θgFn-0.6438+0.001682×νdn<0.01 (7a) In each embodiment, in order to obtain an even smaller, lighter lens with better optical performance, it is preferable that the negative lens constituting the third lens unit L3 has a meniscus shape convex toward the image side and satisfies the following conditional expression (8).

[0044] -10.0<(Rpf+Rpr) / (Rpf-Rpr)<-1.0 ···(8) In conditional expression (8), Rpf and Rpr are the radii of curvature on the object side and image side of the negative lens constituting the third lens group L3, respectively. Conditional expression (8) is a shape factor indicating the meniscus shape of the negative lens constituting the third lens group L3. If the upper limit of conditional expression (8) is exceeded, the radius of curvature on the object side of the negative lens becomes small, spherical aberration is overcorrected, and it becomes difficult to maintain optical performance. On the other hand, if the lower limit of conditional expression (8) is exceeded, the radius of curvature on the object side of the negative lens becomes large, spherical aberration is undercorrected, and it becomes difficult to maintain optical performance.

[0045] It is even more preferable that the numerical range of conditional expression (8) be set as in the following conditional expression (8a).

[0046] -5.0<(Rpf+Rpr) / (Rpf-Rpr)<-1.1 (8a) In each embodiment, in order to obtain a smaller size and higher optical performance, it is preferable that the fourth lens group L4 is composed of two lenses, a positive lens and a positive or negative lens, arranged in that order from the object side to the image side. With this configuration, it is possible to reduce the weight of the fourth lens group L4 and the entire zoom lens system.

[0047] In each embodiment, in order to obtain a smaller size and higher optical performance, it is preferable that the lens (positive lens or negative lens) on the image side of the fourth lens group L4 has an aspheric surface. By locating the aspheric surface in this position, it is possible to reduce the variation in spherical aberration during zooming, and to obtain good optical performance even at the periphery of the screen.

[0048] In each embodiment, in order to obtain a compact and high optical performance, it is preferable that the second lens group L2 is a cemented lens of a negative lens and a positive lens arranged in this order from the object side to the image side. With this configuration, the chromatic aberration of the second lens group L2 can be appropriately controlled, and the chromatic aberration can be corrected to obtain good optical performance. In addition, by moving the second lens group L2 in a direction including a component perpendicular to the optical axis OA, the fluctuation of the chromatic aberration during image stabilization can be suppressed.

[0049] In each embodiment, in order to obtain a compact and high optical performance, it is preferable that the rear group LR has a fifth lens unit L5 with negative refractive power. With this configuration, when a telephoto type power arrangement is adopted at the telephoto end, the negative refractive power on the image side can be made strong, and the overall optical length can be made short.

[0050] In each embodiment, in order to obtain a compact and high optical performance, it is preferable that the fifth lens group L5 with negative refractive power in the rear group LR performs focusing from infinity to a close distance. By using the lens group behind (on the image side) the aperture stop SP, which has a small magnification change function, as the focus lens group, it is possible to reduce the change in image magnification when focusing from infinity to a close distance. This is particularly suitable for video shooting, since it is possible to reduce the change in the angle of view when the subject changes from infinity to a close distance.

[0051] The positive or negative lens on the image side in the fourth lens group L4 is a resin lens. A specific example of such an optical material is a thermoplastic resin of a cycloolefin polymer system. A resin lens has a smaller specific gravity than a glass lens, and the weight of the zoom lens is reduced. However, the material is not limited to these as long as it has a smaller specific gravity than a glass lens.

[0052] With the above-mentioned configuration, it is possible to obtain a small, lightweight zoom lens with excellent optical performance over the entire zoom range in a telephoto type optical system. The zoom lens of each embodiment will be described in detail below. EXAMPLES

[0053] First, a zoom lens 1a according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. The zoom lens 1a is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 and a sixth lens group L6, which are arranged in this order from the object side to the image side, and which both have negative refractive power.

[0054] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a negative meniscus lens L42, which are arranged in this order from the object side to the image side. The negative meniscus lens L42 is made of a resin material.

[0055] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a flat lens with no refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0056] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment. EXAMPLES

[0057] Next, a zoom lens 1b according to a second embodiment of the present invention will be described with reference to Figures 3 and 4. The zoom lens 1b is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 and a sixth lens group L6, which are arranged in this order from the object side to the image side, and which have negative refractive power.

[0058] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a negative meniscus lens L42, which are arranged in this order from the object side to the image side. The negative meniscus lens L42 is made of a resin material.

[0059] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a flat lens with no refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0060] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment. EXAMPLES

[0061] Next, a zoom lens 1c according to a third embodiment of the present invention will be described with reference to Fig. 5 and Fig. 6. The zoom lens 1c is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 with negative refractive power and a sixth lens group L6 with negative refractive power, which are arranged in this order from the object side to the image side.

[0062] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a positive meniscus lens L42, which are arranged in this order from the object side to the image side. The positive meniscus lens L42 is made of a resin material.

[0063] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a negative lens. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0064] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment. EXAMPLES

[0065] Next, a zoom lens 1d according to a fourth embodiment of the present invention will be described with reference to Fig. 7 and Fig. 8. The zoom lens 1d is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 and a sixth lens group L6, which are arranged in this order from the object side to the image side, and which have negative refractive power.

[0066] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a negative meniscus lens L42, which are arranged in this order from the object side to the image side. The negative meniscus lens L42 is made of a resin material.

[0067] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a flat lens with no refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0068] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment. EXAMPLES

[0069] Next, a zoom lens 1e according to a fifth embodiment of the present invention will be described with reference to Fig. 9 and Fig. 10. The zoom lens 1e is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 and a sixth lens group L6, which are arranged in this order from the object side to the image side, and which have negative refractive power.

[0070] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a positive meniscus lens L42, which are arranged in this order from the object side to the image side. The positive meniscus lens L42 is made of a resin material.

[0071] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a flat lens with no refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0072] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment. EXAMPLES

[0073] Next, a zoom lens 1f according to a sixth embodiment of the present invention will be described with reference to Fig. 11 and Fig. 12. The zoom lens 1f is composed of a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a rear group LR, which are arranged in this order from the object side to the image side. The rear group LR is composed of a fifth lens group L5 and a sixth lens group L6, which are arranged in this order from the object side to the image side, and which have negative refractive power.

[0074] The first lens group L1 is composed of a positive lens L11 and a cemented lens of a negative lens L12 and a positive lens L13, which are arranged in this order from the object side to the image side. The second lens group L2 is composed of a cemented lens of a negative lens L21 and a positive lens L22, which are arranged in this order from the object side to the image side. The third lens group L3 is composed of an aperture stop SP, a positive lens L31, and a negative meniscus lens L32 convex toward the image side, which are arranged in this order from the object side to the image side. The fourth lens group L4 is composed of a positive lens L41 and a positive meniscus lens L42, which are arranged in this order from the object side to the image side. The positive meniscus lens L42 is made of a resin material.

[0075] The fifth lens group L5 is composed of a cemented lens of a positive lens L51 and a negative lens L52 arranged in order from the object side to the image side. The sixth lens group L6 is composed of a flat lens with no refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group L1 and the second lens group L2 increases, the distance between the second lens group L2 and the third lens group L3 decreases, the distance between the third lens group L3 and the fourth lens group L4 decreases, and the rear group LR moves on the optical axis. During focusing from infinity to a close distance, the fifth lens group L5 moves toward the image side along the optical axis.

[0076] As is clear from each aberration diagram, various aberrations are well corrected in this embodiment.

[0077] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below. In each numerical example, each surface of the optical system is assigned a surface number i (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) (mm) on the optical axis between the surface with surface number i and the surface with surface number (i+1), and nd is the refractive index for the d-line of the material of the optical member having each surface. νd is the Abbe number for the d-line of the material of the optical member having each surface.

[0078] The focal length (mm), F-number, and half angle of view (°) are values ​​when the optical system is focused on an object at infinity. The total lens length is the distance on the optical axis from the front surface (the lens surface closest to the object) to the final surface (the lens surface closest to the image) of the optical system, plus the back focus BF. The back focus BF is the distance from the final surface of the optical system to the image surface (the air-equivalent distance from the final lens surface to the paraxial image surface).

[0079] An "*" next to a surface number means that the surface has an aspheric shape. An aspheric shape is expressed by the following formula, where x is the displacement from the apex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, the direction of light travel is positive, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, A10, and A12 are aspheric coefficients. The aspheric coefficient "e-xx" is 10 -xx means...

[0080] 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 Values ​​corresponding to conditional expressions (1) to (8) in Numerical Examples 1 to 6 are summarized in Table 1.

[0081] (Numerical Example 1) Unit: mm Surface Data Surface number rd nd νd 1 96.848 4.58 1.48749 70.2 2 -1538.934 0.15 3 97.960 2.00 1.61340 44.3 4 43.522 6.43 1.49700 81.5 5 122.959 (variable) 6 -98.396 1.20 1.77250 49.6 7 27.696 3.01 2.05090 26.9 8 53.328 (variable) 9(Aperture) ∞ 0.80 10 30.325 5.23 1.48749 70.2 11 -50.245 5.50 12 -29.430 1.50 2.00100 29.1 13 -70.595 (variable) 14 452.936 4.17 1.48749 70.2 15 -28.599 3.32 16* 41.480 3.00 1.53110 55.9 17* 40.012 (variable) 18 -1288.012 3.06 1.84666 23.8 19 -42.793 1.20 1.80400 46.5 20 38.589 (variable) 21∞1.30 1.51633 64.1 22 ∞ (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-3.78070e-005 A 6=-1.21129e-007 A 8=-3.09634e-010 A10= 1.17462e-012 Page 17 K = 0.00000e+000 A 4=-3.20663e-005 A 6=-1.15972e-007 A 8=-3.95696e-010 A10= 2.43533e-012 Various data Zoom ratio 3.77 Wide Angle Mid-Telephoto Focal length 103.00 216.56 387.89 F-number 5.82 7.39 8.24 Half angle of view 11.86 5.71 3.19 Image height 21.64 21.64 21.64 Lens total length 183.21 227.16 258.38 BF 39.88 62.29 81.93 d 5 19.55 63.50 94.72 d 8 37.55 21.22 3.53 d13 12.00 5.91 3.97 d17 19.44 12.20 2.73 d20 8.34 15.59 25.05 d22 39.88 62.29 81.93 Zoom lens group data Group starting plane focal length 1 1 194.23 2 6 -57.17 3 9 107.61 4 14 54.31 5 18 -48.75 6 21∞ (Numerical Example 2) Unit: mm Surface Data Surface number rd nd νd 1 98.773 4.60 1.48749 70.2 2 -1094.378 0.15 3 90.004 2.00 1.61340 44.3 4 42.540 6.20 1.49700 81.5 5 104.085 (variable) 6 -116.344 1.20 1.72916 54.7 7 28.368 2.85 2.05090 26.9 8 48.728 (variable) 9(Aperture) ∞ 0.80 10 27.951 5.54 1.48749 70.2 11 -42.619 2.83 12 -32.957 1.50 1.95375 32.3 13 -455.880 (variable) 14 75.047 4.52 1.60311 60.6 15 -35.048 2.09 16* 45.908 3.00 1.53110 55.9 17* 31.890 (variable) 18 241.496 2.68 1.92286 20.9 19 -69.765 1.20 1.88300 40.8 20 36.813 (variable) 21∞1.30 1.51633 64.1 22 ∞ (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-5.20282e-005 A 6=-5.28393e-008 A 8=-2.17741e-010 A10= 1.66219e-012 Page 17 K = 0.00000e+000 A 4=-4.74670e-005 A 6=-3.41109e-008 A 8=-3.26561e-010 A10= 2.58840e-012 Various data Zoom ratio 3.77 Wide Angle Mid-Telephoto Focal length 103.00 222.89 387.85 F-number 5.75 7.45 8.24 Half angle of view 11.86 5.54 3.19 Image height 21.64 21.64 21.64 Lens total length 190.00 233.89 265.06 BF 44.04 68.34 88.09 d 5 22.44 66.33 97.50 d 8 40.90 21.15 3.61 d13 12.22 7.67 5.46 d17 19.62 12.37 2.71 d20 8.34 15.59 25.25 d22 44.04 68.34 88.09 Zoom lens group data Group starting plane focal length 1 1 200.48 2 6 -61.04 3 9 193.61 4 14 46.93 5 18 -51.54 6 21∞ (Numerical Example 3) Unit: mm Surface Data Surface number rd nd νd 1 102.804 4.52 1.48749 70.2 2 -942.943 0.15 3 110.795 2.00 1.61340 44.3 4 45.741 6.53 1.49700 81.5 5 152.786 (variable) 6 -102.315 1.20 1.75500 52.3 7 28.676 2.93 2.05090 26.9 8 54.067 (variable) 9(Aperture) ∞ 0.80 10 32.923 4.85 1.48749 70.2 11 -63.730 4.82 12 -35.426 1.50 2.05090 26.9 13 -108.572 (variable) 14 91.027 4.54 1.53996 59.5 15 -32.480 1.46 16* 49.783 3.00 1.53110 55.9 17* 43.243 (variable) 18 147.917 2.93 1.92286 20.9 19 -82.245 1.20 1.88300 40.8 20 34.470 (variable) 21 -147.758 1.30 1.59522 67.7 22 -320.037 (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-2.40666e-005 A 6=-7.97212e-008 A 8=-1.93457e-010 A10= 6.17436e-013 Page 17 K = 0.00000e+000 A 4=-1.61994e-005 A 6=-7.78080e-008 A 8=-2.63557e-010 A10= 1.13396e-012 Various data Zoom ratio 3.75 Wide Angle Mid-Telephoto Focal length 103.35 214.26 387.77 F-number 5.82 7.31 8.24 Half angle of view 11.82 5.77 3.19 Image height 21.64 21.64 21.64 Lens total length 190.00 234.02 265.09 BF 45.79 66.46 86.74 d 5 20.07 64.09 95.15 d 8 41.89 25.82 7.45 d13 10.27 5.67 3.77 d17 19.59 12.29 2.46 d20 8.66 15.96 25.79 d22 45.79 66.46 86.74 Zoom lens group data Group starting plane focal length 1 1 192.76 2 6 -60.75 3 9 191.67 4 14 46.49 5 18 -53.93 6 21 -462.45 (Numerical Example 4) Unit: mm Surface Data Surface number rd nd νd 1 97.979 4.64 1.48749 70.2 2 -1008.913 0.15 3 94.241 2.00 1.61340 44.3 4 42.618 6.40 1.49700 81.5 5 114.681 (variable) 6 -106.744 1.20 1.75500 52.3 7 28.414 2.98 2.05090 26.9 8 52.202 (variable) 9(Aperture) ∞ 0.80 10 29.270 5.67 1.48749 70.2 11 -42.436 3.68 12 -30.096 1.50 1.85025 30.1 13 -152.213 (variable) 14 221.981 4.31 1.51823 58.9 15 -30.408 3.51 16* 51.871 3.00 1.53110 55.9 17* 44.691 (variable) 18 515.868 2.71 1.92286 20.9 19 -60.058 1.20 1.88300 40.8 20 38.657 (variable) 21∞1.30 1.51633 64.1 22 ∞ (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-5.46707e-005 A 6=-1.12893e-007 A 8=-7.42004e-011 A10= 1.56469e-012 Page 17 K = 0.00000e+000 A 4=-5.09007e-005 A 6=-9.82769e-008 A 8= 1.32982e-011 A10= 1.90268e-012 Various data Zoom ratio 3.76 Wide Angle Mid-Telephoto Focal length 103.00 214.71 387.77 F-number 5.79 7.32 8.24 Half angle of view 11.86 5.75 3.19 Image height 21.64 21.64 21.64 Lens total length 185.00 228.69 260.16 BF 42.31 64.98 86.46 d 5 16.44 60.13 91.60 d 8 40.00 22.73 3.59 d13 13.89 8.49 6.14 d17 19.12 11.87 2.27 d20 8.21 15.46 25.07 d22 42.31 64.98 86.46 Zoom lens group data Group starting plane focal length 1 1 193.10 2 6 -59.74 3 9 118.31 4 14 54.32 5 18 -49.27 6 21∞ (Numerical Example 5) Unit: mm Surface Data Surface number rd nd νd 1 132.654 5.69 1.48749 70.2 2 -1033.578 0.20 3 144.804 2.50 1.61340 44.3 4 59.816 7.26 1.49700 81.5 5 200.000 (variable) 6 -106.658 1.80 1.77250 49.6 7 35.060 4.56 2.05090 26.9 8 68.942 (variable) 9(Aperture) ∞ 1.19 10 33.537 6.03 1.48749 70.2 11 -79.649 9.25 12 -35.795 2.00 2.00100 29.1 13 -91.179 (variable) 14 -77.084 3.28 1.48749 70.2 15 -30.018 10.26 16* 129.613 4.00 1.53110 55.9 17* -1769.683 (variable) 18 -8365.787 3.19 1.84666 23.8 19 -58.604 1.80 1.80400 46.5 20 51.522 (variable) 21∞1.93 1.51633 64.1 22 ∞ (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-4.03529e-005 A 6=-1.04123e-007 A 8= 2.67850e-012 A10=-3.15135e-013 Page 17 K = 0.00000e+000 A 4=-3.68960e-005 A 6=-8.74780e-008 A 8= 1.03207e-010 A10=-1.72503e-013 Various data Zoom ratio 3.80 Wide Angle Mid-Telephoto Focal length 153.00 328.55 581.90 F-number 8.00 10.26 11.31 Half angle of view 8.05 3.77 2.13 Image height 21.64 21.64 21.64 Lens length 274.81 319.32 354.89 BF 68.40 102.29 126.51 d 5 44.31 88.82 124.39 d 8 58.14 27.89 3.39 d13 10.52 6.88 7.16 d17 20.02 14.46 2.49 d20 8.47 14.04 26.00 d22 68.40 102.29 126.51 Zoom lens group data Group starting plane focal length 1 1 244.96 2 6 -68.62 3 9 133.19 4 14 70.76 5 18 -66.79 6 21∞ (Numerical Example 6) Unit: mm Surface Data Surface number rd nd νd 1 137.987 5.46 1.48749 70.2 2 -1546.758 0.20 3 193.562 2.50 1.61340 44.3 4 67.305 7.64 1.49700 81.5 5 500.000 (variable) 6 -101.769 1.80 1.77250 49.6 7 31.879 3.89 2.05090 26.9 8 61.953 (variable) 9(Aperture) ∞ 1.19 10 33.593 5.72 1.48749 70.2 11 -114.082 9.82 12 -38.356 2.00 2.00100 29.1 13 -120.188 (variable) 14 -158.725 3.68 1.51633 64.1 15 -32.193 12.03 16* 141.213 4.00 1.53110 55.9 17* -559.264 (variable) 18 1037.884 3.06 1.92286 20.9 19 -73.351 1.80 1.88300 40.8 20 53.111 (variable) 21∞1.93 1.51633 64.1 22 ∞ (variable) Image plane ∞ Aspheric Data Page 16 K = 0.00000e+000 A 4=-4.64647e-005 A 6=-1.28525e-007 A 8= 2.52244e-011 A10=-6.53496e-013 Page 17 K = 0.00000e+000 A 4=-4.37120e-005 A 6=-1.05428e-007 A 8= 1.36931e-010 A10=-3.04580e-013 Various data Zoom ratio 3.80 Wide Angle Mid-Telephoto Focal length 153.00 330.53 581.87 F-number 8.00 10.50 11.31 Half angle of view 8.05 3.74 2.13 Image height 21.64 21.64 21.64 Lens total length 285.00 320.05 360.14 BF 72.60 108.49 124.92 d 5 48.74 83.79 123.89 d 8 58.99 25.57 8.57 d13 9.45 6.99 7.55 d17 20.30 18.25 2.49 d20 8.19 10.25 26.00 d22 72.60 108.49 124.92 Zoom lens group data Group starting plane focal length 1 1 230.43 2 6 -63.11 3 9 199.38 4 14 59.21 5 18 -66.02 6 21∞

[0082] [Table 1]

[0083] Next, an imaging device will be described with reference to Fig. 14. Fig. 14 is a schematic diagram of an imaging device (single-lens reflex camera system) 100 that uses any one of the zoom lenses 1a to 1f of Examples 1 to 6 as an imaging optical system.

[0084] In FIG. 14, 10 denotes a camera body, 11 denotes an interchangeable lens (imaging optical system) constituted by any one of the zoom lenses 1a to 1f of the first to sixth embodiments. 12 denotes a recording means such as a film or an imaging element for recording an image of a subject formed by the interchangeable lens 11. The recording means 12 receives an image formed by the imaging optical system. 13 denotes a viewfinder optical system for observing the image of a subject from the interchangeable lens 11. 14 denotes a quick-return mirror that rotates to switch and transmit the image of a subject formed by the interchangeable lens 11 to the recording means 12 and the viewfinder optical system 13. When observing an image of a subject through a viewfinder, the image of a subject formed on a focusing screen 15 via the quick-return mirror 14 is made into an erect image by a pentaprism 16, and then is magnified and observed by an eyepiece optical system 17. When taking a picture, the quick-return mirror 14 rotates in the direction of the arrow, and the image of a subject is formed on the recording means 12 and recorded. 18 denotes a sub-mirror, and 19 denotes a focus detection device.

[0085] In this way, by applying the zoom lens of each embodiment to an imaging device such as an interchangeable lens for a single-lens reflex camera, an imaging device with high optical performance can be realized. The imaging device may be a mirrorless imaging device that does not have a quick return mirror 14, or may be an integrated lens imaging device that is not an interchangeable lens type.

[0086] According to each embodiment, it is possible to provide a small, lightweight zoom lens and an imaging device that have high optical performance over the entire zoom range.

[0087] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0088] 1a~1f zoom lens L1 First lens group L2 Second lens group L3: Third lens group L4 4th lens group

Claims

1. A zoom lens having, arranged in order from an object side to an image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein a distance between adjacent lens groups changes during zooming from a wide-angle end to a telephoto end, During zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group becomes wider, the distance between the second lens group and the third lens group becomes narrower, and the distance between the third lens group and the fourth lens group becomes narrower, the lens disposed closest to the object side in the first lens group has positive refractive power, the third lens group includes a positive lens and a negative lens arranged in this order from the object side to the image side, When the total optical length of the zoom lens at the telephoto end is TLt, the focal length of the zoom lens at the telephoto end is ft, and the focal length of the third lens group is f3, 0.50 <TLt / ft<0.69 0.10< f3 / ft<0.58 A zoom lens characterized by satisfying the following conditional expressions:

2. When the distance between the positive lens and the negative lens in the third lens group is D3 and the total thickness of the third lens group is LT3, 0.25<D3 / LT3<1.00 2. The zoom lens according to claim 1, wherein the following condition is satisfied:

3. When the Abbe number of the positive lens in the third lens group is νdp, vdp>65 3. The zoom lens according to claim 1, wherein the following condition is satisfied:

4. When the refractive index of the negative lens in the third lens group at the d line is Ndn, Ndn>1.80 4. The zoom lens according to claim 1, wherein the following condition is satisfied:

5. When the Abbe number of the negative lens in the third lens group is νdn and the partial dispersion ratio is θgFn, 25<νdn<45 θgFn-0.6438+0.001682×νdn<0.02 5. The zoom lens according to claim 1, wherein the following condition is satisfied:

6. The negative lens of the third lens group has a meniscus shape convex toward the image side, and when the radii of curvature on the object side and the image side are Rpf and Rpr, respectively, -10.0<(Rpf+Rpr) / (Rpf-Rpr)<-1.0 6. The zoom lens according to claim 1, wherein the following condition is satisfied:

7. 7. The zoom lens according to claim 1, wherein the fourth lens group is composed of two lenses, a positive lens and a positive or negative lens, arranged in that order from the object side to the image side.

8. 8. The zoom lens according to claim 1, wherein the positive lens or the negative lens provided on the image side of the fourth lens group has an aspheric surface.

9. 9. The zoom lens according to claim 1, wherein the second lens group is made up of a cemented lens of a negative lens and a positive lens arranged in this order from the object side to the image side.

10. 10. The zoom lens according to claim 1, further comprising a sixth lens group arranged closer to the image side than the fifth lens group.

11. 11. The zoom lens according to claim 1, wherein the fifth lens group is a focus lens group that performs focusing from infinity to a close distance.

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

Images