Zoom lens and image capturing device

Abstract

To provide a compact, light-weight zoom lens which exhibits little variation in optical performance while focusing.SOLUTION: A zoom lens L0 provided herein comprises, in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2, a third lens group L3, and a rear group LR comprising multiple lens groups. When zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, thereby increasing a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the rear group. The rear group includes a focusing lens group having negative refractive power. When shifting focus from an object at infinity to a nearby object, the focusing lens group moves toward the object side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a zoom lens suitable for imaging.

Background Art

[0002] Among zoom lenses used for imaging, there is a so-called positive lead type zoom lens in which a lens group with the most positive refractive power on the object side is arranged to meet the requirements of being small and lightweight and having little variation in optical performance during focusing. Also, a floating method in which a plurality of lens groups are moved during focusing is used.

[0003] Patent Document 1 discloses a zoom lens having a first lens group with positive refractive power arranged on the object side, in which the distance between adjacent lens groups changes during zooming, and a plurality of lens groups are moved during focusing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, in order to miniaturize a zoom lens, it is effective to adopt a telephoto type power arrangement at the telephoto end and strengthen the positive refractive power on the object side and the negative refractive power on the image side. However, when the refractive power of each lens group is strengthened, the variation of various aberrations accompanying zooming becomes large, and it becomes difficult to correct various aberrations well with a small number of lenses. Also, in a positive lead type zoom lens, since the effective diameter of the lens group on the object side becomes large, the configuration of the lens group on the object side for weight reduction is important.

[0006] Furthermore, in a telephoto zoom lens, the amount of movement of the focus lens group tends to be large during focusing. Therefore, the arrangement of the focus lens group for suppressing fluctuations in optical performance during focusing is important.

[0007] The present invention provides a zoom lens that is small and lightweight and has little fluctuation in optical performance during focusing.

Means for Solving the Problems

[0008] The zoom lens according to one aspect of the present invention includes a lens group arranged in order from the object side to the image side, which consists of a first lens group with positive refractive power, a second lens group, a third lens group, and a rear group including a plurality of lens groups. During zooming, the distance between adjacent lens groups changes. When zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, 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 increases, and the distance between the third lens group and the rear group increases. The rear group includes a focus lens group with negative refractive power. The focus lens group is characterized by moving toward the object side during focusing from an infinite object to a close object. In addition, an imaging device equipped with the above zoom lens also constitutes another aspect of the present invention.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a zoom lens that is small and lightweight and has little fluctuation in optical performance during focusing.

Brief Description of the Drawings

[0010]

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Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] Figs. 1, 4, 7, 10, 13, and 16 each show a cross-section of the zoom lens L0 of Examples 1 to 6 in a state of being focused on an object at infinity at the wide-angle end (hereinafter referred to as the infinity focus state). The zoom lens L0 of each example is used in an imaging device such as a digital video camera, a digital still camera, a broadcast camera, a silver halide film camera, a surveillance camera, etc., or an optical device including an interchangeable lens. Furthermore, it can also be used in an observation optical device such as a telescope.

[0013] In each cross-sectional view, the left side is the object side (front side), and the right side is the image side (rear side). The zoom lens L0 of each embodiment has a plurality of lens groups each having a refractive power. In a zoom lens, a lens group is a collection of one or more lenses that move integrally during zooming (changing magnification) between the wide-angle end and the telephoto end. That is, the distance between adjacent lens groups changes during zooming. A lens group may include a diaphragm. Also, the wide-angle end and the telephoto end respectively indicate the zoom states of the maximum picture angle (shortest focal length) and the minimum picture angle (longest focal length) when the lens group that moves during zooming is located at both ends of the range where it can move mechanically or controllably on the optical axis. Further, the refractive power is the reciprocal of the focal length.

[0014] In each cross-sectional view, Li represents the i-th lens group counted from the object side among the plurality of lens groups included in the zoom lens L0. LR is a rear group including all the lens groups arranged on the image side of the third lens group L3. LIS is an anti-vibration group having a function (anti-vibration function) of moving in a direction including a component in a direction orthogonal to the optical axis to correct image blur due to camera shake or the like. The anti-vibration group may be the whole of one lens group or a subgroup that is a part of the lens group. A subgroup is a collection of one or more lenses whose constituent length (the distance from the most object-side surface to the most image-side surface of the subgroup) remains unchanged during zooming.

[0015] Also, SP is a diaphragm. IP is an image plane. On the image plane IP, an imaging surface (light-receiving surface) of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a film surface (photosensitive surface) of a silver halide film is arranged. Note that an optical element such as a parallel plate or a prism having no refractive power, such as a low-pass filter or an infrared cut filter, may be arranged between the lens arranged on the most image side of the zoom lens L0 and the image plane IP.

[0016] In each sectional view, below the lens group that moves during zooming, the movement trajectory during zooming from the wide-angle end to the telephoto end of the lens group is simplified and shown by a solid arrow. Also, below the focus lens group that moves during focusing, the movement direction during focusing from an infinite object to a close object of the lens group is shown by a dashed arrow.

[0017] First, the characteristics common to the zoom lens L0 of each embodiment will be described. The zoom lens L0 of each embodiment is a positive-reading zoom lens with the refractive power of the first lens group L1 being positive. In the zoom lens L0 of each embodiment, the lens groups arranged in order from the object side to the image side are composed of a first lens group L1 with a positive refractive power, a second lens group L2, a third lens group L3, and a rear group LR including a plurality of lens groups. The rear group LR is composed of all the lens groups (the third lens group L3 to the seventh lens group L7 or the eighth lens group L8) arranged on the image side of the third lens group L3.

[0018] In the zoom lens L0 of each embodiment, during zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, 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 increases, and the distance between the third lens group L3 and the rear group LR increases. As a result, a telephoto-type power arrangement is formed at the telephoto end, which is advantageous for shortening the overall length of the zoom lens L0.

[0019] Generally, the larger the focal length of the zoom lens at the telephoto end, the easier it is for the first lens group with positive refractive power to become larger. This is because the higher the incident height of the chief ray for the lens arranged on the object side at the telephoto end, the larger the effective diameter (the radius of the region through which the rays contributing to imaging pass). Therefore, increasing the distance from the first lens group makes it easier to reduce the effective diameter, which facilitates the weight reduction of the zoom lens. This is because the volume (mass) of the lens is approximately proportional to the cube of the effective diameter.

[0020] In this regard, in the zoom lens L0 of each embodiment, since the distance from the first lens group L1 of the rear group LR increases at the telephoto end, it is easy to reduce the diameter.

[0021] Further, the rear group LR includes a focus lens group having a negative refractive power. The focus lens group moves toward the object side when focusing from an infinite object to a close object. By making a part of the rear group LR the focus lens group in this way, it becomes easy to reduce the size and weight of the focus lens group, and rapid focusing becomes possible. Also, since the change in the height of the incident height of the on-axis ray in the rear group LR is small, it becomes easy to reduce the aberration variation during focusing by making a part of the rear group LR the focus lens group.

[0022] Furthermore, in the zoom lens L0 of each embodiment, when zooming from the wide-angle end to the telephoto end, the distance between the focus lens group and the lens group adjacent to the focus lens group on the object side increases, and the focus lens group moves toward the object side when focusing from an infinite object to a close object. As a result, the drive mechanism for zooming can also be used as the drive mechanism for focusing, so it becomes easy to simplify the drive mechanism, and by efficiently changing the lens group interval, it becomes easy to reduce the size of the zoom lens.

[0023] Note that the number of focus lens groups included in the rear group LR may be one, but in the zoom lens L0 of each embodiment, it has a first focus lens group (Focus) as the main focus lens group having a negative refractive power, and a second focus lens group (Floating) as a floating group arranged on the image side thereof. The second focus lens group moves independently (i.e., along a different locus) from the first focus lens group during focusing.

[0024] With the above configuration, a zoom lens that is small and lightweight and has little variation in optical performance during focusing can be obtained.

[0025] Also, the zoom lens L0 of each embodiment preferably satisfies at least one of the conditions of the following formulas (1) to (13).

[0026] 4.4 ≦ D2t / D2w ≦ 15.0 (1) -2.8 ≦ fL1 / fL2 ≦ 3.0 (2) 0.15 ≦ |ML1 / TLw| ≦ 0.90 (3) 0.05 ≦ |ML3 / TLw| ≦ 0.40 (4) 0.05 ≦ |ML3 / ML1| ≦ 0.80 (5) |ML2 / ML1| ≦ 0.20 (6) |ML2 / ML3| ≦ 0.40 (7) 0.03 ≦ Skw / fL1 ≦ 0.50 (8) 0.20 ≦ |MF1 / MF2| ≦ 5.00 (9) 60 ≦ νdL1Pave. ≦ 99 (10) 60 ≦ νdL2Pave. ≦ 99 (11) 20 ≦ νdL2Nave. ≦ 45 (12) 1.40 ≦ ndG1 ≦ 1.70 (13) The condition of formula (1) shows an appropriate relationship between the distance D2w on the optical axis from the most object-side surface (the frontmost surface) of the zoom lens L0 at the wide-angle end to the most image-side surface of the second lens group L2 and the distance D2t on the optical axis from the frontmost surface to the most image-side surface of the second lens group L2 at the telephoto end. By satisfying the condition of formula (1), the total thickness of the first lens group L1 and the second lens group L2 can be reduced at the wide-angle end, and furthermore, the effective diameter of the second lens group L2 can be reduced at the telephoto end, so that the zoom lens can be easily lightened. If the distance D2t becomes too small so that D2t / D2w is below the lower limit value of formula (1), the effective diameter of the second lens group L2 becomes large, making it difficult to lighten the zoom lens L0, which is not preferable. If the distance D2t becomes too large so that D2t / D2w exceeds the upper limit value of formula (1), it becomes difficult to miniaturize the zoom lens L0 at the telephoto end, which is not preferable.

[0027] The condition of Equation (2) shows an appropriate relationship between the focal length fL1 of the first lens group L1 and the focal length fL2 of the second lens group L2. By satisfying the condition of Equation (2), the refractive power of the first lens group L1 becomes stronger, and it becomes easier to correct chromatic aberration at the telephoto end. If the focal length fL1 of the first lens group L1 becomes too long (the refractive power becomes too weak) such that fL1 / fL2 exceeds the upper limit value or is below the lower limit value of Equation (2), it becomes difficult to correct chromatic aberration at the telephoto end, which is not preferable.

[0028] The condition of Equation (3) shows an appropriate relationship between the movement amount ML1 of the first lens group L1 during zooming from the wide-angle end to the telephoto end and the overall optical length TLw of the zoom lens L0 at the wide-angle end. The movement amount of the lens group during zooming from the wide-angle end to the telephoto end is the difference in the positions of the lens group on the optical axis at the wide-angle end and the telephoto end, excluding the reciprocating movement amount, and the sign of the movement amount is set to be positive when the lens group is located on the image side at the telephoto end compared to the wide-angle end. Also, the overall optical length TLw is the distance on the optical axis from the outermost front surface of the zoom lens L0 to the image plane IP. If the movement amount ML1 of the first lens group L1 becomes too small such that |ML1 / TLw| is below the lower limit value of Equation (3), it becomes difficult to ensure a high magnification ratio, which is not preferable. If the movement amount ML1 of the first lens group L1 becomes too large such that |ML1 / TLw| exceeds the upper limit value of Equation (3), it becomes difficult to miniaturize the zoom lens L0 at the telephoto end, which is not preferable.

[0029] The condition of Equation (4) shows an appropriate relationship between the movement amount ML3 of the third lens group L3 during zooming from the wide-angle end to the telephoto end and the overall optical length TLw of the zoom lens L0 at the wide-angle end. If the movement amount ML3 of the third lens group L3 becomes too small such that |ML3 / TLw| is below the lower limit value of Equation (4), it becomes difficult to ensure a high magnification ratio, which is not preferable. Also, if the movement amount ML3 of the third lens group L3 becomes too large such that |ML3 / TLw| exceeds the upper limit value of Equation (4), it becomes difficult to miniaturize the zoom lens L0 at the wide-angle end, which is not preferable.

[0030] The condition of Equation (5) shows an appropriate relationship between the movement amount ML1 of the first lens group L1 and the movement amount ML3 of the third lens group L3 when zooming from the wide-angle end to the telephoto end. If the movement amount ML1 of the first lens group L1 becomes too small such that |ML3 / ML1| is below the lower limit value of Equation (5), it becomes difficult to ensure a high magnification ratio, which is not preferable. If the movement amount ML1 of the first lens group L1 becomes too large such that |ML3 / ML1| exceeds the upper limit value of Equation (5), it becomes difficult to miniaturize the zoom lens L0 at the telephoto end, which is not preferable.

[0031] The condition of Equation (6) shows an appropriate relationship between the movement amount ML2 of the second lens group L2 and the movement amount ML1 of the first lens group L1 when zooming from the wide-angle end to the telephoto end. If the movement amount ML2 of the second lens group L2 becomes too large such that |ML2 / ML1| exceeds the upper limit value of Equation (6), it becomes difficult to miniaturize the zoom lens L0 at the wide-angle end, which is not preferable.

[0032] The condition of Equation (7) shows an appropriate relationship between the movement amount ML2 of the second lens group L2 and the movement amount ML3 of the third lens group L3 when zooming from the wide-angle end to the telephoto end. If the movement amount ML2 of the second lens group L2 becomes too large such that |ML2 / ML3| exceeds the upper limit value of Equation (7), it becomes difficult to miniaturize the zoom lens L0 at the wide-angle end, which is not preferable.

[0033] The condition of Equation (8) shows an appropriate relationship between the back focus Skw of the zoom lens L0 at the wide-angle end and the focal length fL1 of the first lens group L1. If the back focus Skw at the wide-angle end becomes too short such that Skw / fL1 is below the lower limit value of Equation (8), it becomes difficult to arrange an optical element such as a low-pass filter near the image plane IP where the imaging surface of the imaging device is arranged, which is not preferable. If the back focus SKw becomes too long such that Skw / fL1 exceeds the upper limit value of Equation (8), the overall optical length of the zoom lens L0 at the wide-angle end becomes long, making miniaturization difficult, which is not preferable.

[0034] The condition of Equation (9) shows an appropriate relationship between the movement amount MF1 when the first focusing lens group focuses from an infinite object to a close object at the telephoto end and the movement amount MF2 when the second focusing lens group focuses from an infinite object to a close object at the telephoto end. The movement amount of the focusing lens group when focusing from an infinite object to a close object is the difference in the positions on the optical axis where the first focusing lens group focuses on the infinite object and the close object, respectively, and does not include the reciprocating movement amount. Also, when the position where the focusing lens group focuses on the close object is on the object side compared to the position where it focuses on the infinite object, the sign of the movement amount is defined as positive. If the movement amount MF1 of the first focusing lens group becomes too small such that |MF1 / MF2| is below the lower limit value of Equation (9), it becomes difficult to suppress the variations in spherical aberration and other various aberrations during focusing, which is not preferable. Also, if the movement amount MF1 of the first focusing lens group becomes too large such that |MF1 / MF2| exceeds the upper limit value of Equation (9), the variations in spherical aberration and other various aberrations during focusing become large, which is not preferable.

[0035] The condition of Equation (10) shows an appropriate range of the average value νdL1Pave. of the Abbe numbers based on the d-line of all the positive lenses among at least one positive lens included in the first lens group L1. If νdL1Pave. is below the lower limit value of Equation (10), it becomes difficult to correct the axial chromatic aberration and magnification chromatic aberration at the telephoto end, which is not preferable. If νdL1Pave. exceeds the upper limit value of Equation (10), the dispersion of all the positive lenses included in the first lens group L1 becomes too small, making it difficult to correct the magnification chromatic aberration at the wide-angle end, which is not preferable.

[0036] The condition of Equation (11) indicates an appropriate range for the average value νdL2Pave. of the Abbe number based on the d-line of all positive lenses among the positive lenses included in at least one of the second lens groups L2. If νdL2Pave. is below the lower limit value of Equation (11), it becomes difficult to correct the axial chromatic aberration and magnification chromatic aberration at the telephoto end, which is not preferable. If νdL2Pave. exceeds the upper limit value of Equation (11), the dispersion of all positive lenses included in the second lens group L2 becomes too small, making it difficult to correct the magnification chromatic aberration at the wide-angle end, which is not preferable.

[0037] The condition of Equation (12) indicates an appropriate range for the average value νdL2Nave. of the Abbe number based on the d-line of all negative lenses among the negative lenses included in at least one of the second lens groups L2. If νdL2Nave. is below the lower limit value of Equation (12), it becomes difficult to correct the magnification chromatic aberration at the wide-angle end, which is not preferable. If νdL2Nave. exceeds the upper limit value of Equation (12), it becomes difficult to correct the axial chromatic aberration and magnification chromatic aberration at the telephoto end, which is not preferable.

[0038] The condition of Equation (13) indicates an appropriate range for the refractive index ndG1 at the d-line of the most object-side positive lens G1 in the first lens group L1. If ndG1 is below the lower limit value of Equation (13), the curvature of the surface increases to obtain the required refractive power, and as a result, higher-order spherical aberration occurs, which is not preferable. If ndG1 exceeds the upper limit value of Equation (13), it is advantageous for miniaturization of the first lens group L1, but the refractive power becomes too strong, making it difficult to balance with the correction of distortion aberration when correcting spherical aberration, which is not preferable.

[0039] Note that it is more preferable if the numerical ranges of Equations (1) to (13) are as follows.

[0040] 4.5 ≦ D2t / D2w ≦ 14.0 (1a) -2.0 ≦ fL1 / fL2 ≦ 2.0 (2a) 0.20 ≦ |ML1 / TLw| ≦ 0.80 (3a) 0.07 ≦ |ML3 / TLw| ≦ 0.30 (4a) 0.10 ≤ |ML3 / ML1| ≤ 0.70 (5a) |ML2 / ML1| ≤ 0.10 (6a) |ML2 / ML3| ≤ 0.30 (7a) 0.04 ≤ Skw / fL1 ≤ 0.40 (8a) 0.25 ≤ |MF1 / MF2| ≤ 4.00 (9a) 63 ≤ νdL1Pave. ≤ 97 (10a) 65 ≤ νdL2Pave. ≤ 97 (11a) 23 ≤ νdL2Nave. ≤ 40 (12a) 1.42 ≤ ndG1 ≤ 1.65 (13a) Also, when the numerical ranges of formulas (1) to (13) are as follows, it is more preferable.

[0041] 4.6 ≤ D2t / D2w ≤ 13.0 (1b) -1.5 ≤ fL1 / fL2 ≤ 1.5 (2b) 0.25 ≤ |ML1 / TLw| ≤ 0.75 (3b) 0.10 ≤ |ML3 / TLw| ≤ 0.25 (4b) 0.15 ≤ |ML3 / ML1| ≤ 0.60 (5b) |ML2 / ML1| ≤ 0.05 (6b) |ML2 / ML3| ≤ 0.20 (7b) 0.05 ≤ Skw / fL1 ≤ 0.30 (8b) 0.30 ≤ |MF1 / MF2| ≤ 3.00 (9b) 65 ≤ νdL1Pave. ≤ 96 (10b) 70 ≤ νdL2Pave. ≤ 96 (11b) 25 ≤ νdL2Nave. ≤ 37 (12b) 1.43 ≤ ndG1 ≤ 1.60 (13b) Next, the preferable configurations satisfied by the zoom lens L0 of each example will be described.

[0042] The first lens group L1 is preferably composed of two or fewer single lenses. This makes it easy to reduce the weight of the first lens group L1. In the case where there is one cemented lens in which a plurality (for example, two) of lenses are cemented, it is regarded as including a plurality (two) of lenses.

[0043] The second lens group L2 is preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the second lens group L2. The third lens group L3 is preferably composed of four or fewer lenses. The third lens group L3 is more preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the third lens group L3.

[0044] The first focusing lens group is preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the first focusing lens group. The second focusing lens group is preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the second focusing lens group.

[0045] The rear group LR preferably includes an anti-shake group. By using a part of the lens groups or subgroups of the rear group LR as the anti-shake group, the size of the anti-shake group can be reduced, making it easy to miniaturize the zoom lens.

[0046] The rear group LR preferably includes three or more lens groups, and the interval between adjacent lens groups preferably changes during zooming. Further, the rear group LR more preferably includes four or more lens groups, and the interval between adjacent lens groups preferably changes during zooming. By moving a large number of lens groups during zooming, aberration variation during zooming can be suppressed, making it easy to ensure a high magnification ratio.

[0047] The third lens group L3 preferably moves toward the image side during zooming from the wide-angle end to the telephoto end. By arranging the third lens group L3 on the image side at the telephoto end, it is easy to reduce the size and weight of the third lens group L3.

[0048] The aperture stop SP preferably moves independently of the third lens group L3 (i.e., along a different locus) during zooming. This facilitates reduction of the aperture diameter of the aperture stop SP, and further facilitates downsizing of the zoom lens L0.

[0049] Next, the configurations of the zoom lenses L0 of the respective embodiments will be specifically described. The zoom lenses L0 of Embodiment 1 and Embodiment 2 are composed of a first lens group L1, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, a sixth lens group L6 with positive refractive power, and a seventh lens group L7 with negative refractive power. The fourth lens group L4 to the seventh lens group L7 are included in the rear group LR. An aperture stop SP is disposed on the most object side in the fifth lens group L5.

[0050] In the zoom lenses L0 of Embodiments 1 and 2, during zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, the second lens group L2 does not move, and the third lens group L3 and the fourth lens group L4 move toward the image side. Also, the fifth lens group L5 to the seventh lens group L7 move toward the object side. When focusing from an infinite object to a close object, the fourth lens group L4 moves toward the object side as the first focus lens group, and the seventh lens group L7 moves toward the image side as the second focus lens group.

[0051] The zoom lens L0 of Embodiment 3 is composed of a first lens group L1, a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, a sixth lens group L6 with negative refractive power, a seventh lens group L7 with positive refractive power, and an eighth lens group L8 with negative refractive power. The fourth lens group L4 to the eighth lens group L8 are included in the rear group LR. An aperture stop SP is disposed between the fourth lens group L4 and the fifth lens group L5.

[0052] In the zoom lens L0 of Example 3, when zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, the second lens group L2 does not move, the third lens group L3 and the fourth lens group L4 move toward the image side, and the fifth lens group L5 to the eighth lens group L8 move toward the object side. When focusing from an infinite object to a close object, the fourth lens group L4 moves toward the object side as the first focus lens group, and the sixth lens group L6 moves toward the image side as the second focus lens group.

[0053] The zoom lens L0 of Example 4 is composed of a first lens group L1, a second lens group L2 with positive refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, a sixth lens group L6 with negative refractive power, a seventh lens group L7 with positive refractive power, and an eighth lens group L8 with negative refractive power. The fourth lens group L4 to the eighth lens group L8 are included in the rear group LR. An aperture stop SP is disposed between the fourth lens group L4 and the fifth lens group L5.

[0054] In the zoom lens L0 of Example 4, when zooming from the wide-angle end to the telephoto end, the first lens group L1 and the second lens group L2 move toward the object side, the third lens group L3 and the fourth lens group L4 move toward the image side, and the fifth lens group L5 to the eighth lens group L8 move toward the object side. When focusing from an infinite object to a close object, the fourth lens group L4 moves toward the object side as the first focus lens group, and the sixth lens group L6 moves toward the image side as the second focus lens group.

[0055] The zoom lens L0 of Example 5 is composed of a first lens group L1, a second lens group L2 with positive refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with negative refractive power, a fifth lens group L5 with positive refractive power, a sixth lens group L6 with negative refractive power, a seventh lens group L7 with positive refractive power, and an eighth lens group L8 with negative refractive power. The fourth lens group L4 to the eighth lens group L8 are included in the rear group LR. An aperture stop SP is disposed between the fourth lens group L4 and the fifth lens group L5.

[0056] In the zoom lens L0 of Example 5, when zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, the second lens group L2 to the fourth lens group L4 move toward the image side, and the fifth lens group L5 to the eighth lens group L8 move toward the object side. When focusing from an infinite object to a close object, the fourth lens group L4 moves toward the object side as the first focus lens group, and the sixth lens group L6 moves toward the image side as the second focus lens group.

[0057] The zoom lens L0 of Example 6 is composed of a first lens group L1, a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, a sixth lens group L6 with positive refractive power, a seventh lens group L7 with positive refractive power, and an eighth lens group L8 with negative refractive power. The fourth lens group L4 to the eighth lens group L8 are included in the rear group LR. An aperture stop SP is disposed on the most object side in the sixth lens group L6.

[0058] In the zoom lens L0 of Example 6, when zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, the second lens group L2 does not move, the third lens group L3 to the fifth lens group L5 move toward the image side, and the sixth lens group L6 to the eighth lens group L8 move toward the object side. When focusing from an infinite object to a close object, the fifth lens group L5 moves toward the object side as the first focus lens group, and the eighth lens group L8 moves toward the image side as the second focus lens group.

[0059] The numerical examples 1 to 6 corresponding to each of Examples 1 to 6 are shown below. In the surface data of each numerical example, the surface number i indicates the order of the surface when counted from the object side. r is the radius of curvature (mm) of the i-th surface, d is the lens thickness or air gap (mm) on the optical axis between the i-th surface and the (i + 1)-th surface, and nd is the refractive index of the optical material between the i-th surface and the (i + 1)-th surface at the d-line. νd is the Abbe number based on the d-line of the optical material between the i-th surface and the (i + 1)-th surface. The Abbe number νd based on the d-line is expressed as νd = (Nd - 1) / (NF - NC), 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, respectively.

[0060] The above d, focal length (mm), F-number, and half angle (°) are all values in the infinitely focused state. BF represents the back focus (mm). The back focus is defined as the distance on the optical axis from the most image-side surface (the final surface) of the zoom lens to the paraxial image plane, expressed in terms of the air-equivalent length. The overall lens length is the length obtained by adding the back focus to the distance on the optical axis from the frontmost surface to the final surface of the zoom lens, corresponding to the overall optical length.

[0061] The "*" attached to the surface number means that the surface has an aspherical shape. The aspherical shape is expressed by the following formula when X is the displacement amount from the surface vertex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, the direction of light propagation is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, A10, A12, A14 are the aspherical coefficients. "e±XX" in the conic constant and aspherical coefficients means "×10± XX ".

[0062] 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 +A14×h 14 ​​Also, the values regarding the conditions of formulas (1) to (13) for each numerical example are summarized in Table 1. Numerical examples 1 to 6 satisfy the conditions of formulas (1) to (13).

[0063] Figures 2, 5, 8, 11, 14, and 17 respectively show the longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the zoom lens L0 of numerical examples 1 to 6 in (A) the wide-angle end and infinity focus state and (B) the wide-angle end and focus on a nearest object state (hereinafter referred to as the nearest focus state). Also, Figures 3, 6, 9, 12, 15, and 18 respectively show the longitudinal aberrations of the zoom lens L0 of numerical examples 1 to 6 in (A) the telephoto end and infinity focus state and (B) the telephoto end and nearest focus state.

[0064] In the spherical aberration figure, Fno indicates the F-number, the solid line indicates the spherical aberration with respect to the d-line (wavelength 587.6 nm), and the two-dot chain line indicates the spherical aberration with respect to the g-line (wavelength 435.8 nm). In the astigmatism figure, the solid line ΔS indicates the astigmatism on the sagittal image plane, and the broken line ΔM indicates the astigmatism on the meridional image plane. The distortion aberration figure shows the distortion aberration at the d-line. The chromatic aberration figure shows the magnification chromatic aberration at the g-line. ω is the half field angle (°) and indicates the field angle by paraxial calculation. [Numerical Example 1] Unit: mm Surface data Surface number r d nd νd 1 164.651 6.49 1.49700 81.5 2 -992.849 (variable) 3 54.679 8.78 1.43387 95.1 4 -164.854 0.10 5 -177.402 1.25 1.77047 29.7 6 88.934 (variable) 7 125.120 4.12 1.85478 24.8 8 -202.791 0.15 9 -3344.207 1.20 1.59282 68.6 10 57.245 (variable) 11 -55.760 1.20 1.59282 68.6 12 53.178 1.99 1.91650 31.6 13 102.063 (variable) 14 (aperture) ∞ 0.30 15 29.957 7.74 1.43387 95.1 16 -327.003 0.15 17 28.976 5.20 1.49700 81.7 18 94.576 5.59 19 -170.402 1.15 1.80610 40.7 20 25.369 1.99 21 30.481 4.64 1.49700 81.7 22 -186.228 0.90 1.89286 20.4 23 53.091 0.10 1.58946 30.6 24* 57.945 0.15 25 47.373 4.16 1.77047 29.7 26 -71.660 0.95 27 86.275 5.37 1.89286 20.4 28 -25.672 0.90 1.91082 35.2 29 29.058 (variable) 30 28.044 5.65 1.72047 34.7 31 -35.472 1.00 1.95906 17.5 32 -370.146 (variable) 33 1623.915 0.80 1.90043 37.4 34 28.414 5.20 1.66565 35.6 35 -40.950 0.10 1.58946 30.6 36* -40.526 0.91 37 -30.022 0.90 1.49700 81.7 38 44.272 (variable) Image plane ∞ Aspherical data 24th surface K = 0.00000e+00 A 4= 7.41455e-06 A 6= 2.87737e-09 A 8=-2.41337e-11 A10= 1.40485e-13 A12=-2.80246e-16 36th surface K = 0.00000e+00 A 4=-3.89934e-06 A 6=-1.16405e-08 A 8= 2.43384e-10 A10=-2.46472e-12 A12= 9.07277e-15 Various data Zoom ratio 4.70 Wide angle Middle Telephoto Focal length 103.18 203.65 484.84 F number 4.63 5.35 6.43 Half field angle (°) 11.84 6.06 2.56 Image height 21.64 21.64 21.64 Overall lens length 238.21 282.76 337.21 BF 57.29 67.63 91.05 d 2 0.90 45.45 99.90 d 6 1.69 14.42 34.11 d10 18.44 26.09 24.83 d13 71.89 38.03 3.11 d29 0.66 1.56 2.85 d32 8.22 10.47 2.25 d38 57.29 67.63 91.05 Lens group data Group Starting surface Focal length 1 1 284.69 2 3 -530.88 3 7 1405.98 4 11 -73.58 5 14 100.94 6 30 45.71 7 33 -52.14 [Numerical Example 2] Unit: mm Surface data Surface number r d nd νd 1 215.133 5.22 1.43875 94.7 2 -1177.812 (variable) 3 61.606 8.31 1.43387 95.1 4 -135.709 0.10 5 -161.855 1.25 1.77047 29.7 6 94.133 (variable) 7 165.786 3.43 2.00069 25.5 8 -234.343 0.15 9 480.831 1.20 1.49700 81.7 10 63.848 (variable) 11 -62.530 1.20 1.59282 68.6 12 57.960 2.45 1.89190 37.1 13 117.437 (variable) 14 (aperture) ∞ 0.30 15 31.104 9.11 1.43387 95.1 16 -229.645 0.15 17 29.443 4.72 1.49700 81.7 18 71.851 7.75 19 -105.672 1.15 1.75500 52.3 20 26.867 2.59 21* 34.801 4.37 1.49700 81.7 22 -146.809 0.90 1.86966 20.0 23 74.586 0.15 24 78.321 3.30 1.80518 25.5 25 -87.066 0.95 26 58.772 7.13 1.89286 20.4 27 -26.869 0.90 1.96300 24.1 28 31.789 (Variable) 29 33.056 5.09 1.73037 32.2 30 -68.071 1.00 1.95906 17.5 31 -427.866 (Variable) 32 97.457 0.80 1.90043 37.4 33 17.340 10.09 1.60342 38.0 34 -26.337 0.80 35* -20.317 0.90 1.49700 81.7 36* 51.161 (Variable) Image plane ∞ Aspherical data The 21st surface K = 0.00000e+00 A 4=-4.85175e-06 A 6= 9.97592e-10 A 8=-1.83474e-11 A10= 1.53669e-13 A12=-4.61385e-16 The 35th surface K = 0.00000e+00 A 4= 6.09133e-06 A 6= 1.24869e-07 A 8=-8.74896e-10 A10= 2.74942e-12 A12= 1.35020e-15 The 36th surface K = 0.00000e+00 A 4=-1.34235e-05 A 6= 9.27560e-08 A 8=-8.88026e-10 A10= 2.96304e-12 A12=-2.48349e-15 Various data Zoom ratio 4.71 Wide angle Middle Telephoto Focal length 103.03 205.48 484.97 F-number 4.63 5.35 6.43 Half field angle (°) 11.86 6.01 2.55 Image height 21.64 21.64 21.64 Overall lens length 239.52 312.59 401.90 BF 45.64 67.32 97.77 d2 0.90 73.97 163.28 d6 2.04 12.66 32.86 d10 14.46 18.66 15.52 d13 82.05 46.16 3.34 d28 1.12 2.71 3.41 d31 7.87 5.66 0.28 d36 45.64 67.32 97.77 Lens group data Group Starting surface Focal length 1 1 415.08 2 3 -442.00 3 7 273.06 4 11 -83.51 5 14 107.00 6 29 47.56 7 32 -52.06 [Numerical example 3] Unit: mm Surface data Surface number r d nd νd 1 180.558 8.49 1.49700 81.5 2 -1632.774 (variable) 3 66.970 10.00 1.43387 95.1 4 -292.843 0.03 5 -331.366 1.45 1.80610 33.3 6 119.345 (variable) 7 286.937 3.06 1.85478 24.8 8 -196.659 0.15 9 -658.113 1.25 1.59282 68.6 10 74.834 (variable) 11 -63.788 1.20 1.59282 68.6 12 87.224 2.18 1.77047 29.7 13 232.533 (variable) 14 (aperture) ∞ (variable) 15 39.833 8.03 1.43387 95.1 16 -176.245 0.15 17 53.637 4.41 1.49700 81.5 18 777.726 0.15 19 47.028 6.56 1.49700 81.5 20 -76.418 1.40 1.75500 52.3 21 55.274 14.53 22 -98.263 2.73 1.66565 35.6 23 -30.173 1.00 1.72916 54.7 24 34.552 1.50 25 52.362 1.00 1.95906 17.5 26 39.279 4.11 1.48749 70.2 27 -61.481 0.10 1.58946 30.6 28* -79.328 0.15 29 38.935 2.99 1.61340 44.3 30 789.408 (variable) 31 237.194 1.92 1.77047 29.7 32 -114.123 0.85 1.88300 40.8 33 68.900 (variable) 34 -257.247 2.43 1.56732 42.8 35 - 59.691 (Variable) 36 - 42.272 1.20 1.43875 94.7 37 88.047 8.14 1.51742 52.4 38 - 26.932 1.20 1.49700 81.5 39 218.375 (Variable) Image plane ∞ Aspherical data 28th surface K = 0.00000e+00 A4 = 6.76027e - 07 A6 = 2.49893e - 09 A8 = - 2.91480e - 11 A10 = 1.94933e - 13 A12 = - 4.85325e - 16 Various data Zoom ratio 5.66 Wide - angle Middle Telephoto Focal length 103.31 199.40 584.79 F - number 4.63 5.65 6.49 Half - field angle (°) 11.83 6.19 2.12 Image height 21.64 21.64 21.64 Overall lens length 284.16 346.98 389.09 BF 37.71 39.02 78.98 d2 0.90 63.72 105.83 d6 2.50 29.42 51.02 d10 15.39 26.31 26.80 d13 62.94 25.10 3.02 d14 35.60 35.61 - 0.28 d30 2.00 7.47 1.34 d33 27.87 22.41 28.54 d35 6.90 5.58 1.51 d39 37.71 39.02 78.98 Lens group data Group starting surface, focal length 1 1 327.63 2 3 -1181.41 3 7 -701.45 4 11 -94.26 5 15 62.25 6 31 -95.31 7 34 136.40 8 36 -90.07 [Numerical example 4] Unit: mm Surface data Surface number r d nd νd 1 269.981 4.95 1.59349 67.0 2 2061.875 (variable) 3 77.510 7.78 1.43387 95.1 4 -341.399 0.30 5 -297.104 1.45 1.80610 33.3 6 79.900 0.14 7 81.238 6.06 1.43387 95.1 8 -882.841 (variable) 9 262.461 3.71 1.85478 24.8 10 -157.690 0.15 11 -573.290 1.25 1.59282 68.6 12 93.819 (variable) 13 -183.917 1.20 1.59282 68.6 14 65.292 3.13 1.66565 35.6 15 419.646 3.25 16 -56.219 1.00 1.43875 94.7 17 387.874 (variable) 18 (aperture) ∞ (variable) 19 40.123 7.64 1.43387 95.1 20 -178.847 0.15 21 60.169 3.76 1.59282 68.6 22 520.049 0.15 23 45.371 6.66 1.49700 81.7 24 -76.645 1.40 1.72916 54.7 25 52.490 16.28 26 -72.032 2.82 1.73037 32.2 27 -25.361 1.00 1.74400 44.8 28 34.670 2.66 29 55.716 1.00 1.95906 17.5 30 39.268 4.08 1.48749 70.2 31* -81.737 0.15 32 39.223 3.57 1.61340 44.3 33 -276.942 (variable) 34 463.197 1.89 1.68430 26.8 35 -108.432 0.85 1.88300 40.8 36 65.081 (variable) 37 4254.102 3.91 1.53172 48.8 38 -50.478 (variable) 39 -41.498 1.20 1.43875 94.7 40 83.511 7.50 1.51742 52.4 41 -35.690 1.20 1.43875 94.7 42 123.111 (variable) Image plane ∞ Aspherical data The 31st surface K = 0.00000e+00 A 4= 1.15289e-06 A 6=-5.59256e-10 A 8= 1.61123e-11 A10=-4.37103e-14 A12=-1.07538e-16 Various data Zoom ratio 5.68 Wide angle, intermediate, telephoto Focal length 103.05, 193.32, 584.97 F-number 4.64, 5.65, 6.49 Half field angle (°) 11.86, 6.39, 2.12 Image height 21.64, 21.64, 21.64 Overall lens length 286.09, 402.13, 485.09 BF 37.92, 39.96, 76.42 d2 0.90, 116.88, 199.78 d8 0.98, 21.47, 40.59 d12 10.07, 20.63, 31.69 d17 61.89, 30.90, 0.78 d18 35.94, 34.48, 2.19 d33 1.45, 4.25, 1.49 d36 28.37, 25.57, 28.33 d38 6.33, 5.74, 1.57 d42 37.92, 39.96, 76.42 Lens group data Group, starting surface, focal length 1, 1, 522.91 2, 3, 9459.33 3, 9, 722.28 4, 13, -78.06 5, 19, 62.32 6, 34, -71.94 7, 37, 93.85 8, 39, -90.25 [Numerical example 5] Unit: mm Surface data Surface number, r, d, nd, νd 1, 249.947, 2.87, 1.49700, 81.7 2, 506.076, 0.15 3 159.697 5.81 1.43387 95.1 4 1509.843 (variable) 5 125.288 5.34 1.49700 81.7 6 -296.401 0.31 7 -253.883 1.45 1.83400 37.2 8 84.599 0.15 9 83.338 5.44 1.59282 68.6 10 -1443.043 (variable) 11 631.408 2.73 1.85478 24.8 12 -161.518 0.15 13 -509.568 1.25 1.59282 68.6 14 87.535 (variable) 15 -221.759 1.20 1.59282 68.6 16 58.637 3.29 1.66565 35.6 17 426.730 3.01 18 -56.885 1.00 1.49700 81.7 19 558.854 (variable) 20 (aperture) ∞ (variable) 21 47.779 7.14 1.43387 95.1 22 -134.953 0.15 23 66.001 4.11 1.59282 68.6 24 804.355 0.15 25 54.394 6.63 1.49700 81.7 26 -81.105 1.40 1.74400 44.8 27 65.118 19.81 28 -55.737 2.26 1.74951 35.3 29 -29.304 1.00 1.61997 63.9 30 37.868 3.17 31 62.476 1.00 1.96300 24.1 32 38.936 3.54 1.53775 74.7 33* -381.530 0.15 34 46.452 3.70 1.65160 58.5 35 -126.812 (Variable) 36 477.057 1.89 1.80810 22.8 37 -111.706 0.85 1.88300 40.8 38 66.620 (Variable) 39 1273.663 3.44 1.51823 58.9 40 -64.646 (Variable) 41 -53.012 1.20 1.49700 81.7 42 71.145 10.67 1.51633 64.1 43 -26.451 1.20 1.49700 81.7 44 -1149.855 (Variable) Image plane ∞ Aspherical data The 33rd surface K = 0.00000e+00 A 4= 1.40271e-06 A 6=-2.47421e-10 A 8= 1.80038e-11 A10=-1.20178e-13 A12= 2.66081e-16 Various data Zoom ratio 4.71 Wide angle Middle Telephoto Focal length 103.01 175.25 484.99 F-number 4.63 5.65 6.49 Half field angle (°) 11.86 7.04 2.55 Image height 21.64 21.64 21.64 Overall lens length 286.01 334.52 365.98 BF 37.99 33.33 77.03 d 4 0.90 49.91 81.86 d10 1.00 20.06 33.56 d14 8.95 19.86 27.35 d19 55.19 24.71 3.24 d20 31.10 36.32 -0.25 d35 1.50 4.94 1.49 d38 32.63 29.19 32.64 d40 9.14 8.59 1.46 d44 37.99 33.33 77.03 Lens group data Group Starting surface Focal length 1 1 291.18 2 5 9682.04 3 11 -801.59 4 15 -78.35 5 21 63.90 6 36 -81.97 7 39 118.82 8 41 -127.35 [Numerical example 6] Unit: mm Surface data Surface number r d nd νd 1 197.124 5.90 1.49700 81.5 2 -782.793 (Variable) 3 52.622 9.59 1.43875 94.7 4 -417.306 1.25 1.77047 29.7 5 90.372 (Variable) 6 -811.869 3.30 1.66565 35.6 7 -111.574 0.15 8 -147.836 1.20 1.59282 68.6 9 98.887 (Variable) 10 2234.164 3.14 1.76182 26.5 11 -129.162 (Variable) 12 -59.773 1.20 1.59282 68.6 13 50.104 2.35 1.95375 32.3 14 93.685 (Variable) 15 (Aperture) ∞ 0.30 16 30.767 7.44 1.43387 95.1 17 -262.308 0.15 18 32.073 3.90 1.49700 81.7 19 86.891 7.86 20 -124.894 1.15 1.80610 40.7 21 27.616 1.53 22 26.746 4.49 1.49700 81.7 23 -422.814 0.90 1.89286 20.4 24 42.919 0.10 1.58946 30.6 25* 50.472 0.15 26 45.722 3.93 1.77047 29.7 27 -64.700 0.95 28 145.730 4.31 1.89286 20.4 29 -25.519 0.90 1.91082 35.2 30 35.172 (Variable) 31 35.306 5.48 1.72047 34.7 32 -42.894 1.00 1.95906 17.5 33 -298.101 (Variable) 34 523.176 0.80 1.90043 37.4 35 20.681 7.38 1.66565 35.6 36 -34.825 0.10 1.58946 30.6 37* -38.323 1.49 38 -24.141 0.90 1.49700 81.7 39 58.518 (Variable) Image plane ∞ Aspherical data 25th surface K = 0.00000e+00 A 4= 9.74936e-06 A 6= 3.68108e-09 A 8= 2.18763e-11 A10=-2.63909e-13 A12= 9.77618e-16 37th surface K = 0.00000e+00 A 4=-9.37220e-06 A 6=-2.15979e-08 A 8= 1.80501e-10 A10=-1.75052e-12 A12= 5.97397e-15 Various data Zoom ratio 4.70 Wide angle Middle Telephoto Focal length 103.07 201.02 484.94 F-number 4.63 5.35 6.43 Half field angle (°) 11.85 6.14 2.55 Image height 21.64 21.64 21.64 Overall lens length 239.60 284.15 338.60 BF 38.37 51.67 87.04 d 2 0.90 45.45 99.90 d 5 4.51 16.38 31.20 d 9 3.10 3.10 6.01 d11 14.66 19.39 19.76 d14 79.10 44.03 3.36 d30 0.98 8.02 7.04 d33 14.69 12.81 0.99 d39 38.37 51.67 87.04 Lens group data Group Starting surface Focal length 1 1 317.48 2 3 -2387.23 3 6 -206.08 4 10 160.37 5 12 -77.22 6 15 103.13 7 31 54.98 8 34 -46.92

[0065]

Table 1

[0066] [Imaging device] FIG. 19 shows an imaging device (digital still camera) 10 using the zoom lens L0 of Examples 1 to 6 as an imaging optical system. The imaging device 10 includes a camera body 13, a zoom lens 11 (L0) of any one of Examples 1 to 6, and an imaging element 12 that photoelectrically converts an optical image formed by the zoom lens 11 (images a subject).

[0067] Since the imaging device 10 is provided with a zoom lens 11 that is small and has high optical performance, a high-quality captured image can be obtained. Note that various aberrations such as distortion aberration and chromatic aberration of the captured image acquired by the imaging element 12 may be corrected electrically.

[0068] [Imaging system] An imaging system including the zoom lens L0 of each example and a control unit that controls the zoom lens L0, for example, a surveillance camera system, may be configured. In this case, the control unit can control the zoom lens L0 so that each lens group moves as described above during zooming, focusing, and anti-shake. At this time, the control unit does not necessarily have to be integrally configured with the zoom lens L0, and the control unit may be configured separately from the zoom lens L0. For example, a configuration may be adopted in which a control device as a control unit disposed remotely from a driving unit that drives each lens of the zoom lens L0 includes a transmission unit that sends a control signal (command) for controlling the zoom lens L0. According to such a control unit, the zoom lens L0 can be remotely operated.

[0069] Also, a configuration may be adopted in which an operation unit such as a controller and buttons for remotely operating the zoom lens L0 is provided in the control unit, and the zoom lens L0 is controlled according to an input from the user to the operation unit. For example, an enlargement button and a reduction button may be provided as the operation unit. In this case, when the user presses the enlargement button, the magnification of the zoom lens L0 increases, and when the user presses the reduction button, a signal is sent from the control unit to the drive unit of the zoom lens L0 so that the magnification of the zoom lens L0 decreases.

[0070] Also, the imaging system may have a display unit such as a liquid crystal panel that displays information related to the zooming of the zoom lens L0. Information related to the zooming includes the zoom magnification (zoom state), the movement amount of each lens group (movement state), and the like. In this case, the user can remotely operate the zoom lens L0 via the operation unit while viewing the information related to the zooming of the zoom lens L0 shown on the display unit. At this time, the display unit and the operation unit may be integrated by adopting a touch panel.

[0071] The above embodiments include the following configurations.

[0072] (Configuration 1) The lens groups arranged in order from the object side to the image side include a first lens group with positive refractive power, a second lens group, a third lens group, and a rear group including a plurality of lens groups. During zooming, the distance between adjacent lens groups changes. The zoom lens is such that During zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, 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 increases, and the distance between the third lens group and the rear group increases. The rear group includes a focus lens group with negative refractive power. The focus lens group is characterized in that it moves toward the object side during focusing from an infinite object to a close object. (Configuration 2) When the distance on the optical axis from the most object-side surface of the zoom lens at the wide-angle end to the most image-side surface of the second lens group is D2w, and the distance on the optical axis from the most object-side surface of the second lens group to the most image-side surface of the second lens group at the telephoto end is D2t, 4.4 ≦ D2t / D2w ≦ 15.0 The zoom lens according to Configuration 1, characterized by satisfying the condition. (Configuration 3) When the focal length of the first lens group is fL1 and the focal length of the second lens group is fL2, -2.8 ≦ fL1 / fL2 ≦ 3.0 The zoom lens according to Configuration 1 or 2, characterized by satisfying the condition. (Configuration 4) The rear group includes three or more lens groups, In the rear group, the distance between adjacent lens groups changes during zooming. The zoom lens according to any one of Configurations 1 to 3. (Configuration 5) When the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1 and the overall optical length of the zoom lens at the wide-angle end is TLw, 0.15 ≦ |ML1 / TLw| ≦ 0.90 The zoom lens according to any one of Configurations 1 to 4, characterized by satisfying the condition. (Configuration 6) When the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3 and the overall optical length of the zoom lens at the wide-angle end is TLw, 0.05 ≦ |ML3 / TLw| ≦ 0.40 The zoom lens according to any one of Configurations 1 to 5, characterized by satisfying the condition. (Configuration 7) When the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1 and the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3, 0.05 ≦ |ML3 / ML1| ≦ 0.80 The zoom lens according to any one of Configurations 1 to 6, characterized by satisfying the following conditions. (Configuration 8) When the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end is ML2, and the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1, |ML2 / ML1| ≦ 0.20 The zoom lens according to any one of Configurations 1 to 7, characterized by satisfying the following conditions. (Configuration 9) When the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end is ML2, and the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3, |ML2 / ML3| ≦ 0.40 The zoom lens according to any one of Configurations 1 to 8, characterized by satisfying the following conditions. (Configuration 10) When the back focus of the zoom lens at the wide-angle end is Skw, and the focal length of the first lens group is fL1, 0.03 ≦ Skw / fL1 ≦ 0.50 The zoom lens according to any one of Configurations 1 to 9, characterized by satisfying the following conditions. (Configuration 11) The rear group has a first focus lens group as the focus lens group, and a second focus lens group that is disposed on the image side of the first focus lens group and moves during focusing. When the movement amount of the first focus lens group during focusing from an infinite object to a closest object at the telephoto end is MF1, and the movement amount of the second focus lens group during focusing from an infinite object to a closest object at the telephoto end is MF2, 0.20 ≦ |MF1 / MF2| ≦ 5.00 The zoom lens according to any one of Configurations 1 to 10, characterized by satisfying the following conditions. (Configuration 12) The first lens group includes at least one positive lens. When the average value of the Abbe numbers of all the positive lenses included in the first lens group with respect to the d-line is νdL1Pave., 60 ≦ νdL1Pave. ≦ 99 The zoom lens according to any one of Configurations 1 to 11, characterized by satisfying the condition. (Configuration 13) The second lens group includes at least one positive lens. When the average value of the Abbe numbers of all the positive lenses included in the second lens group with respect to the d-line is νdL2Pave., 60 ≦ νdL2Pave. ≦ 99 The zoom lens according to any one of Configurations 1 to 12, characterized by satisfying the condition. (Configuration 14) The second lens group includes at least one negative lens. When the average value of the Abbe numbers of all the negative lenses included in the second lens group with respect to the d-line is νdL2Nave., 20 ≦ νdL2Nave. ≦ 45 The zoom lens according to any one of Configurations 1 to 13, characterized by satisfying the condition. (Configuration 15) The first lens group includes at least one positive lens. When the refractive index at the d-line of the positive lens arranged closest to the object side among the at least one positive lens is ndG1, 1.40 ≦ ndG1 ≦ 1.70 The zoom lens according to any one of Configurations 1 to 14, characterized by satisfying the condition. (Configuration 16) The zoom lens according to any one of Configurations 1 to 15, characterized in that the first lens group is composed of two or fewer single lenses. (Configuration 17) The zoom lens according to any one of Configurations 1 to 16, characterized in that the second lens group is composed of three or fewer lenses. (Configuration 18) The zoom lens according to any one of Configurations 1 to 17, wherein the third lens group is composed of four or fewer lenses. (Configuration 19) The zoom lens according to any one of Configurations 1 to 18, wherein the first focus lens group is composed of three or fewer lenses. (Configuration 20) The zoom lens according to any one of Configurations 1 to 19, wherein the second focus lens group is composed of three or fewer lenses. (Configuration 21) The zoom lens according to any one of Configurations 1 to 20, wherein at least a part of one lens group included in the rear group is an anti-vibration group that moves with respect to the optical axis in order to reduce image blur. (Configuration 22) The zoom lens according to any one of Configurations 1 to 21, wherein the third lens group moves toward the image side during zooming from the wide-angle end to the telephoto end. (Configuration 23) The zoom lens according to any one of Configurations 1 to 22, wherein the rear group includes an aperture stop, and the aperture stop moves independently of the third lens group during zooming. (Configuration 24) The zoom lens according to any one of Configurations 1 to 23, wherein the lens groups constituting the zoom lens are, in order from the object side to the image side, the first lens group, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the fourth lens group having a negative refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a positive refractive power, and the seventh lens group having a negative refractive power. (Configuration 25) The zoom lens according to any one of Configurations 1 to 23, wherein the lens groups constituting the zoom lens are, in order from the object side to the image side, a plurality of lens groups, the first lens group, the second lens group having a negative refractive power, the third lens group having a negative refractive power, the fourth lens group having a negative refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a negative refractive power, the seventh lens group having a positive refractive power, and the eighth lens group having a negative refractive power. (Configuration 26) The lens groups constituting the zoom lens are, in order from the object side to the image side, the first lens group, the second lens group having a positive refractive power, the third lens group having a positive refractive power, the fourth lens group having a negative refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a negative refractive power, the seventh lens group having a positive refractive power, and the eighth lens group having a negative refractive power, and the zoom lens according to any one of Configurations 1 to 23, characterized in that it consists of these. (Configuration 27) The lens groups constituting the zoom lens are, in order from the object side to the image side, the first lens group, the second lens group having a positive refractive power, the third lens group having a negative refractive power, the fourth lens group having a negative refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a negative refractive power, the seventh lens group having a positive refractive power, and the eighth lens group having a negative refractive power, and the zoom lens according to any one of Configurations 1 to 23, characterized in that it consists of these. (Configuration 28) The lens groups constituting the zoom lens are, in order from the object side to the image side, the first lens group, the second lens group having a negative refractive power, the third lens group having a negative refractive power, the fourth lens group having a positive refractive power, the fifth lens group having a negative refractive power, the sixth lens group having a positive refractive power, the seventh lens group having a positive refractive power, and the eighth lens group having a negative refractive power, and the zoom lens according to any one of Configurations 1 to 23, characterized in that it consists of these. (Configuration 29) A zoom lens according to any one of Configurations 1 to 28, and an imaging device having an imaging element that images a subject through the zoom lens.

[0073] Each of the embodiments described above is merely a representative example, and various modifications and changes can be made to each embodiment when implementing the present invention.

Explanation of Reference Numerals

[0074] L0 Zoom lens L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group L5, 5th lens group L6, 6th lens group L7, 7th lens group L8, 8th lens group LR, rear group LIS, anti-vibration group

Claims

1. A zoom lens in which a lens group arranged in order from the object side to the image side consists of a first lens group having a positive refractive power, a second lens group, a third lens group, and a rear group including a plurality of lens groups, and the distance between adjacent lens groups changes during zooming, during zooming from the wide-angle end to the telephoto end, the first lens group moves toward the object side, 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 increases, and the distance between the third lens group and the rear group increases, the rear group includes a focus lens group having a negative refractive power, the focus lens group is characterized in that it moves toward the object side during focusing from an infinite object to a close object.

2. When the distance on the optical axis from the most object-side surface of the zoom lens at the wide-angle end to the most image-side surface of the second lens group is D2w, and the distance on the optical axis from the most object-side surface to the most image-side surface of the second lens group at the telephoto end is D2t, 4.4 ≤ D2t / D2w ≤ 15.0 The zoom lens according to claim 1, characterized in that the condition is satisfied.

3. When the focal length of the first lens group is fL1 and the focal length of the second lens group is fL2, -2.8 ≤ fL1 / fL2 ≤ 3.0 The zoom lens according to claim 1, characterized in that the condition is satisfied.

4. the rear group includes three or more lens groups, In the rear group, the distance between adjacent lens groups changes during zooming. The zoom lens according to claim 1, characterized in that.

5. When the moving amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1 and the overall optical length of the zoom lens at the wide-angle end is TLw, 0.15 ≤ |ML1 / TLw| ≤ 0.90 The zoom lens according to claim 1, characterized by satisfying the following conditions.

6. When the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3, and the overall optical length of the zoom lens at the wide-angle end is TLw, 0.05 ≤ |ML3 / TLw| ≤ 0.40 The zoom lens according to claim 1, characterized by satisfying the following conditions.

7. When the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1, and the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3, 0.05 ≤ |ML3 / ML1| ≤ 0.80 The zoom lens according to claim 1, characterized by satisfying the following conditions.

8. When the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end is ML2, and the movement amount of the first lens group during zooming from the wide-angle end to the telephoto end is ML1, |ML2 / ML1| ≤ 0.20 The zoom lens according to claim 1, characterized by satisfying the following conditions.

9. When the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end is ML2, and the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end is ML3, |ML2 / ML3| ≤ 0.40 The zoom lens according to claim 1, characterized by satisfying the following conditions.

10. When the back focus of the zoom lens at the wide-angle end is Skw, and the focal length of the first lens group is fL1, 0.03 ≤ Skw / fL1 ≤ 0.50 The zoom lens according to claim 1, characterized by satisfying the following conditions.

11. The rear group includes a first focus lens group as the focus lens group, and a second focus lens group disposed on the image side of the first focus lens group and moving during focusing. When the moving amount during focusing of the first focus lens group from an infinite object to a closest object at the telephoto end is MF1, and the moving amount during focusing of the second focus lens group from an infinite object to a closest object at the telephoto end is MF2, 0.20 ≤ |MF1 / MF2| ≤ 5.00 The zoom lens according to claim 1, characterized in that it satisfies the condition.

12. The first lens group includes at least one positive lens. When the average value of the Abbe numbers of all the positive lenses included in the first lens group with respect to the d-line is νdL1Pave., 60 ≤ νdL1Pave. ≤ 99 The zoom lens according to claim 1, characterized in that it satisfies the condition.

13. The second lens group includes at least one positive lens. When the average value of the Abbe numbers of all the positive lenses included in the second lens group with respect to the d-line is νdL2Pave., 60 ≤ νdL2Pave. ≤ 99 The zoom lens according to claim 1, characterized in that it satisfies the condition.

14. The second lens group includes at least one negative lens. When the average value of the Abbe numbers of all the negative lenses included in the second lens group with respect to the d-line is νdL2Nave., 20 ≤ νdL2Nave. ≤ 45 The zoom lens according to claim 1, characterized in that it satisfies the condition.

15. The first lens group includes at least one positive lens. When the refractive index at the d-line of the positive lens disposed closest to the object side among the at least one positive lens is ndG1, 1.40 ≤ ndG1 ≤ 1.70 The zoom lens according to claim 1, characterized by satisfying the following conditions.

16. The zoom lens according to claim 1, characterized in that the first lens group is composed of two or fewer single lenses.

17. The zoom lens according to claim 1, characterized in that the second lens group is composed of three or fewer lenses.

18. The zoom lens according to claim 1, characterized in that the third lens group is composed of four or fewer lenses.

19. The zoom lens according to claim 1, characterized in that the first focus lens group is composed of three or fewer lenses.

20. The zoom lens according to claim 1, characterized in that the second focus lens group is composed of three or fewer lenses.

21. The zoom lens according to claim 1, characterized in that at least a part of one lens group included in the rear group is an anti-shake group that moves with respect to the optical axis in order to reduce image blur.

22. The zoom lens according to claim 1, characterized in that the third lens group moves toward the image side when zooming from the wide-angle end to the telephoto end.

23. The zoom lens according to claim 1, characterized in that the rear group includes an aperture stop, and the aperture stop moves independently of the third lens group during zooming.

24. The zoom lens according to claim 1, characterized in that the lens groups constituting the zoom lens are, in order from the object side to the image side, the first lens group, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the fourth lens group having a negative refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a positive refractive power, and the seventh lens group having a negative refractive power.

25. The zoom lens is composed of a plurality of lens groups arranged in order from the object side to the image side, including the first lens group, the second lens group with negative refractive power, the third lens group with negative refractive power, the fourth lens group with negative refractive power, the fifth lens group with positive refractive power, the sixth lens group with negative refractive power, the seventh lens group with positive refractive power, and the eighth lens group with negative refractive power. The zoom lens according to claim 1, characterized in that it consists of these lens groups.

26. The zoom lens is composed of a plurality of lens groups arranged in order from the object side to the image side, including the first lens group, the second lens group with positive refractive power, the third lens group with positive refractive power, the fourth lens group with negative refractive power, the fifth lens group with positive refractive power, the sixth lens group with negative refractive power, the seventh lens group with positive refractive power, and the eighth lens group with negative refractive power. The zoom lens according to claim 1, characterized in that it consists of these lens groups.

27. The zoom lens is composed of a plurality of lens groups arranged in order from the object side to the image side, including the first lens group, the second lens group with positive refractive power, the third lens group with negative refractive power, the fourth lens group with negative refractive power, the fifth lens group with positive refractive power, the sixth lens group with negative refractive power, the seventh lens group with positive refractive power, and the eighth lens group with negative refractive power. The zoom lens according to claim 1, characterized in that it consists of these lens groups.

28. The zoom lens is composed of a plurality of lens groups arranged in order from the object side to the image side, including the first lens group, the second lens group with negative refractive power, the third lens group with negative refractive power, the fourth lens group with positive refractive power, the fifth lens group with negative refractive power, the sixth lens group with positive refractive power, the seventh lens group with positive refractive power, and the eighth lens group with negative refractive power. The zoom lens according to claim 1, characterized in that it consists of these lens groups.

29. A zoom lens according to any one of claims 1 to 28, and an imaging device having an imaging element for imaging an object through the zoom lens.

Images