Zoom lens and imaging apparatus

Abstract

To provide a compact and lightweight zoom lens having high optical performance in the entire zoom range.SOLUTION: In a zoom lens L0, lens groups arranged in order from an object side to an image side comprise a first lens group having positive refractive power, a second lens group, and a rear group including a plurality of lens groups. During zooming from a wide angle end to a telephoto end, an interval between the first lens group and the second lens group increases, and an interval between the second lens group and the rear group increases. The distance on an optical axis from the surface closest to the object side of the zoom lens at the wide angle end to the surface closest to the image side of the second lens group is defined as D2w, the distance on an optical axis from the surface closest to the object side at the telephoto end to the surface closest to the image side of the second lens group is defined as D2t, the focal length of the first lens group is defined as fL1, and the focal length of the second lens group is defined as fL2. Conditional expressions 4.4≤D2t / D2w≤15.0 and -2.8≤fL1 / fL2≤3.0 are satisfied.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 having high optical performance and being small and lightweight.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, 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. In addition, 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. Therefore, for miniaturization and weight reduction of a zoom lens, it is important to appropriately set both the refractive power of each lens group and the configuration of the lens group on the object side.

[0006] The present invention provides a small and lightweight zoom lens having high optical performance over the entire zoom range.

Means for Solving the Problems

[0007] As one aspect of the present invention, a zoom lens includes a first lens group having a positive refractive power, a second lens group, and a rear group including a plurality of lens groups, which are arranged in order from the object side to the image side. During zooming, the distance between adjacent lens groups changes. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the rear group increases. 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, 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, the focal length of the first lens group is fL1, and the focal length of the second lens group is fL2, 4.4 ≦ D2t / D2w ≦ 15.0 -2.8 ≦ fL1 / fL2 ≦ 3.0 It is characterized by satisfying the following conditions.

[0008] Also, as another aspect of the present invention, a zoom lens includes a first lens group having a positive refractive power, a second lens group, and a rear group including three or more lens groups, which are arranged in order from the object side to the image side. During zooming, the distance between adjacent lens groups changes. When zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the rear group increases. 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 It is characterized by satisfying the following conditions. Note that 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 small and lightweight zoom lens having high optical performance over the entire zoom range.

Brief Description of the Drawings

[0010]

Figure 1

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Figure 13

Mode for Carrying Out the Invention

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

[0012] FIGS. 1, 3, 5, 7, 9, and 11 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, or the like, or an optical device including an interchangeable lens. Furthermore, it can also be used in an optical device for observation 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 an aperture stop. 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. Also, 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 second lens group L2. LIS is an anti-shake group having a function (anti-shake 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-shake group may be the entire one lens group or a subgroup that is a part of the lens group. The subgroup is a collection of one or more lenses whose construction length (distance from the most object-side lens surface to the most image-side lens surface of the subgroup) is invariant during zooming.

[0015] Also, SP is the aperture stop. IP is the 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 cross-sectional view, below the lens group that moves during zooming, the movement trajectory from the wide-angle end to the telephoto end of the lens group during zooming is simplified and indicated by a solid-line arrow. Also, below the focus lens group that moves during focusing, the movement direction of the lens group from an infinite object to a close-distance object during focusing is indicated by a dashed-line arrow.

[0017] In the zoom lens L0 of each embodiment, the rear group LR includes a first focus lens group (Focus) as the main focus lens group and a second focus lens group (Floating) as a floating group arranged on the image side of this. The second focus lens group moves independently (i.e., along a different trajectory) from the first focus lens group during focusing.

[0018] First, the features common to the zoom lens L0 of each embodiment will be described. The zoom lens L0 of each embodiment is a positive-reading type zoom lens with the refractive power of the first lens group L1 being positive. The zoom lens L0 of each embodiment is composed of a lens group arranged in order from the object side to the image side, which includes a first lens group L1 with a positive refractive power, a second lens group L2, 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 second lens group L2.

[0019] 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, the distance between the first lens group L1 and the second lens group L2 increases, and the distance between the second lens group L2 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.

[0020] In general, as the focal length of the zoom lens at the telephoto end increases, chromatic aberration tends to increase, and the first lens group with positive refractive power tends to become larger. This is because, for the lenses arranged closer to the object side at the telephoto end, the incident height of the on-axis ray becomes higher and the effective diameter (the radius of the region through which the rays contributing to imaging pass) increases. On the other hand, from the perspective of chromatic aberration correction, it is preferable to arrange a plurality of positive lenses formed of low-dispersion materials closer to the object side. However, from the perspective of weight reduction, it is preferable to reduce the effective diameter of the lenses arranged on the object side and minimize the number of lenses arranged on the object side as much as possible. This is because the volume (mass) of the lens is approximately proportional to the cube of the effective diameter.

[0021] Therefore, in the zoom lens L0 of each embodiment, the optical axis distance from the most object-side surface of the zoom lens L0 to the most image-side surface of the second lens group L2 and the refractive powers of the first lens group L1 and the second lens group L2 are appropriately set. Specifically, the zoom lens L0 of each embodiment satisfies the conditions of the following formulas (1) and (2).

[0022] 4.4 ≦ D2t / D2w ≦ 15.0 (1) -2.8 ≦ fL1 / fL2 ≦ 3.0 (2) The condition of formula (1) shows an appropriate relationship between the optical axis distance D2w 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 optical axis distance D2t from the frontmost surface at the telephoto end to the most image-side surface of the second lens group L2. 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, making it easier to reduce the weight of the zoom lens. If the distance D2t becomes too small such 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 reduce the weight of the zoom lens L0, which is not preferable. If the distance D2t becomes too large such 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.

[0023] 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.

[0024] Note that it is more preferable if the numerical ranges of Equations (1) and (2) are as follows.

[0025] 4.5 ≦ D2t / D2w ≦ 14.0 (1a) -2.0 ≦ fL1 / fL2 ≦ 2.0 (2a) Also, it is even more preferable if the numerical ranges of Equations (1) and (2) are as follows.

[0026] 4.6 ≦ D2t / D2w ≦ 13.0 (1b) -1.5 ≦ fL1 / fL2 ≦ 1.5 (2b) By satisfying the above configuration and conditions, a zoom lens L0 having high optical performance in the entire zoom range and being small and lightweight can be obtained.

[0027] Also, the zoom lens L0 of each embodiment preferably satisfies at least one of the conditions of the following Equations (3) to (13).

[0028] 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 (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 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 formula (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 formula (3), it becomes difficult to miniaturize the zoom lens L0 at the telephoto end, which is not preferable.

[0029] The condition of formula (4) shows an appropriate relationship between the movement amount ML3 of the third lens group L3, which is the most object-side lens group in the rear group LR 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 formula (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 formula (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 during 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 during 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 during 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 of the first focusing lens group from an infinite object to a close object during focusing at the telephoto end and the movement amount MF2 of the second focusing lens group from an infinite object to a close object during focusing at the telephoto end. The movement amount of the focusing lens group during focusing from an infinite object to a close object is the difference in the positions on the optical axis where the focusing lens group is focused 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 is focused on the close object is on the object side compared to the position where the focusing lens group is focused on the infinite object, the sign of the movement amount is 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 fluctuations 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 fluctuations 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 of all the positive lenses among the positive lenses included in at least one of the first lens groups L1 with respect to the d-line. If νdL1Pave. is below the lower limit value of Equation (10), it becomes difficult to correct 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, and it becomes difficult to correct 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 the positive lenses among the positive lenses included in at least one of the second lens groups L2. If νdL2Pave. is less than 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 the 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 the negative lenses among the negative lenses included in at least one of the second lens groups L2. If νdL2Nave. is less than 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 less than the lower limit value of Equation (13), the curvature of the surface increases to obtain the necessary 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 achieve both correction of spherical aberration and correction of distortion aberration, which is not preferable.

[0039] It is more preferable that the numerical ranges of Equations (3) to (13) are as follows.

[0040] 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) Further, it is more preferable that the numerical ranges of formulas (3) to (13) are as follows.

[0041] 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, a preferable configuration that the zoom lens L0 of each example satisfies 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 considered to include 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 focus lens group is preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the first focus lens group. The second focus lens group is preferably composed of three or fewer lenses. This makes it easy to reduce the weight of the second focus lens group.

[0045] The rear group LR preferably includes an anti-vibration group. By using a part of the lens groups or subgroups of the rear group LR as the anti-vibration group, the size of the anti-vibration 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 many lens groups during zooming, the 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 (i.e., along a different trajectory) from the third lens group L3 during zooming. This makes it easy to reduce the size of the aperture stop SP and further makes it easy to miniaturize the zoom lens L0.

[0049] Next, the configurations of the zoom lenses L0 of each embodiment 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 Embodiment 1 and Embodiment 2, 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, 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 Embodiment 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 positive 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 negative refractive power, and an eighth lens group L8 with positive refractive power. The third lens group L3 to the eighth lens group L8 are included in the rear group LR. An aperture stop SP is disposed within the fourth lens group L4.

[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, and the third lens group L3 moves toward the image side. Also, the fourth lens group L4 to the seventh lens group L7 move toward the object side, and the eighth lens group L8 does not move. When focusing from an infinite object to a close object, the fifth lens group L5 moves toward the image side as the first focus lens group, and the seventh lens group L7 moves toward the image side as the second focus lens group.

[0059] Hereinafter, numerical examples 1 to 6 corresponding to Examples 1 to 6 are shown. 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 interval (mm) on the optical axis between the i-th surface and the (i + 1)-th surface, 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.

[0060] The above d, focal length (mm), F-number, and semi-field angle (°) are all values in the infinitely focused state. BF represents the back focus (mm). The back focus is expressed 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 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, which corresponds 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 orthogonal to the optical axis, the light propagation direction is taken as positive, R is the paraxial curvature radius, 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) in each numerical example are summarized in Table 1. Numerical examples 1 to 6 satisfy the conditions of formulas (1) to (13).

[0063] Figures 2, 4, 6, 8, 10, and 12 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 infinitely focused state and (B) the wide-angle end and focused on a closest object state (hereinafter referred to as the closest 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 infinitely focused state and (B) the telephoto end and closest focus state.

[0064] ​​ In the spherical aberration diagram, Fno indicates the F number. The solid line represents the spherical aberration for the d line (wavelength 587.6 nm), and the two-dot chain line represents the spherical aberration for the g line (wavelength 435.8 nm). In the astigmatism diagram, the solid line ΔS represents the astigmatism at the sagittal image plane, and the dashed line ΔM represents the astigmatism at the meridional image plane. The distortion diagram shows the distortion at the d line. The chromatic aberration diagram shows the longitudinal chromatic aberration at the g line. ω is the semi-field angle (°) and represents 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 stop) ∞ 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 The 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 The 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, Medium, 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 d2 0.90 45.45 99.90 d6 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 d 2 0.90 73.97 163.28 d 6 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 The 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, intermediate, 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 Surface 31 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 Middle 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 d 2 0.90 116.88 199.78 d 8 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 A4 = 1.40271e-06 A6 = -2.47421e-10 A8 = 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 d4 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 start 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 1 192.186 6.38 1.49700 81.5 2 -508.898 (variable) 3 60.808 8.13 1.43875 94.7 4 -153.103 1.25 1.66565 35.6 5 136.068 (variable) 6 112.014 1.18 1.76385 48.5 7 40.657 4.74 8 -92.208 1.25 1.49700 81.5 9 50.079 2.98 1.85478 24.8 10 193.931 (variable) 11 33.682 7.18 1.49700 81.5 12 -753.639 0.15 13 45.521 4.41 1.43875 94.7 14 747.222 3.44 15 ∞ 4.46 16 -84.823 1.15 1.75500 52.3 17 28.119 1.99 18 39.496 1.10 2.00100 29.1 19 30.015 4.28 1.49700 81.5 20 592.813 0.10 1.58946 30.6 21* 581.298 0.15 22 45.903 3.97 1.51742 52.4 23 -89.697 (Variable) 24 269.188 3.39 1.96300 24.1 25 -31.630 0.90 1.77047 29.7 26 31.876 (Variable) 27* 41.373 0.10 1.58946 30.6 28 41.438 4.95 1.66565 35.6 29 -35.201 1.00 1.95906 17.5 30 -68.199 (Variable) 31 -566.887 1.00 1.81600 46.6 32 22.138 4.61 1.61340 44.3 33 -209.907 0.88 34 -46.521 1.00 1.49700 81.5 35 51.081 (Variable) 36 -93.210 2.70 1.85478 24.8 37 -51.903 (Variable) Image plane ∞ Aspherical data Surface 21 K = 0.00000e+00 A 4= 3.06078e-06 A 6= 1.73892e-10 A 8= 6.89073e-12 A10=-4.56144e-14 A12= 1.05385e-16 Surface 27 K = 0.00000e+00 A 4= 2.47584e-06 A 6= 5.75349e-09 A 8=-5.56712e-11 A10 = 4.81095e-13 A12 = -1.44822e-15 Various data Zoom ratio 4.70 Wide angle, Medium, Telephoto Focal length 103.24, 201.65, 484.75 F-number 4.63, 5.35, 6.43 Half field angle (°) 11.84, 6.12, 2.56 Image height 21.64, 21.64, 21.64 Overall lens length 238.68, 290.83, 336.09 BF 46.01, 46.01, 46.01 d2 0.90, 53.04, 98.31 d5 0.90, 14.97, 46.99 d10 71.48, 40.51, 0.75 d23 13.13, 10.74, 1.02 d26 4.53, 6.92, 16.64 d30 7.61, 9.02, 0.90 d35 15.29, 30.78, 46.65 d37 46.01, 46.01, 46.01 Lens group data Group, Starting surface, Focal length 1, 1, 281.54 2, 3, 890.89 3, 6, -68.01 4, 11, 62.48 5, 24, -70.05 6, 27, 46.57 7, 31, -34.61 8, 36, 133.01

[0065]

Table 1

[0066] [Imaging device] FIG. 13 shows an imaging device (digital still camera) 10 that uses 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 the zoom lens 11 having a small size and 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 electrically corrected.

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

[0070] Further, the imaging system may have a display unit such as a liquid crystal panel that displays information regarding the zooming of the zoom lens L0. The information regarding 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 regarding 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 having a positive refractive power, a second lens group, and a rear group including a plurality of lens groups, and is a zoom lens in which the interval between adjacent lens groups changes during zooming, When zooming from the wide-angle end to the telephoto end, the interval between the first lens group and the second lens group increases, and the interval between the second lens group and the rear group increases, 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, 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, the focal length of the first lens group is fL1, and the focal length of the second lens group is fL2, 4.4 ≦ D2t / D2w ≦ 15.0 -2.8 ≦ fL1 / fL2 ≦ 3.0 A zoom lens characterized by satisfying the following conditions. (Configuration 2) The rear group includes three or more lens groups, The zoom lens according to Configuration 1, wherein, in the rear group, the interval between adjacent lens groups changes during zooming. (Configuration 3) 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 Configuration 1 or 2, characterized by satisfying the following conditions. (Configuration 4) The rear group includes a third lens group on the object side. 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 3, characterized by satisfying the following conditions. (Configuration 5) The rear group includes a third lens group on the object side. 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 4, characterized by satisfying the following conditions. (Configuration 6) 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 5, characterized by satisfying the following conditions. (Configuration 7) The rear group includes a third lens group on the object side. 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 6, characterized by satisfying the following conditions. (Configuration 8) When the back focus of the zoom lens at the wide-angle end is Skw, 0.03 ≦ Skw / fL1 ≦ 0.50 The zoom lens according to any one of Configurations 1 to 7, characterized by satisfying the following conditions. (Configuration 9) The rear group has a first focus lens group that moves during focusing, and a second focus lens group that is disposed closer to the image side than the first focus lens group and moves during focusing. When the movement 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 movement 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 any one of Configurations 1 to 8, characterized by satisfying the following conditions. (Configuration 10) When the first lens group includes at least one positive lens, and 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 9, characterized by satisfying the following conditions. (Configuration 11) When the second lens group includes at least one positive lens, and 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 10, characterized by satisfying the following conditions. (Configuration 12) When the second lens group includes at least one negative lens, and 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 11, characterized by satisfying the following conditions. (Configuration 13) The first lens group includes at least one positive lens. When the refractive index of the positive lens disposed closest to the object side among the at least one positive lens is ndG1 in the d-line, 1.40 ≦ ndG1 ≦ 1.70 The zoom lens according to any one of Configurations 1 to 12, characterized by satisfying the condition. (Configuration 14) The zoom lens according to any one of Configurations 1 to 13, characterized in that the first lens group is composed of two or fewer single lenses. (Configuration 15) The zoom lens according to any one of Configurations 1 to 14, characterized in that the second lens group is composed of three or fewer lenses. (Configuration 16) The zoom lens according to any one of Configurations 1 to 15, characterized in that the third lens group is composed of four or fewer lenses. (Configuration 17) The zoom lens according to any one of Configurations 1 to 16, characterized in that the first focus lens group is composed of three or fewer lenses. (Configuration 18) The zoom lens according to any one of Configurations 1 to 17, characterized in that the second focus lens group is composed of three or fewer lenses. (Configuration 19) The zoom lens according to any one of Configurations 1 to 18, characterized in that 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 20) The rear group includes the third lens group closest to the object side, The zoom lens according to any one of Configurations 1 to 19, characterized in that the third lens group moves toward the image side during zooming from the wide-angle end to the telephoto end. (Configuration 21) The rear group includes the third lens group closest to the object side, and the rear group includes an aperture stop, The zoom lens according to Configuration 20, wherein the aperture stop moves independently of the third lens group during zooming. (Configuration 22) The zoom lens according to any one of Configurations 1 to 21, 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 23) The zoom lens according to any one of Configurations 1 to 21, 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 24) The zoom lens according to any one of Configurations 1 to 21, 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 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. (Configuration 25) The zoom lens according to any one of Configurations 1 to 21, 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 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. (Configuration 26) The zoom lens according to any one of Configurations 1 to 21, 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 positive 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 negative refractive power, and the eighth lens group having a positive refractive power. (Configuration 27) A zoom lens according to any one of Configurations 1 to 26, and an imaging device comprising an imaging element that images a subject through the zoom lens. (Configuration 28) A zoom lens in which the lens groups arranged in order from the object side to the image side include a first lens group having a positive refractive power, a second lens group, and a rear group including three or more lens groups, and the distance between adjacent lens groups changes during zooming, wherein, during zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the rear group increases, 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 and the zoom lens satisfies the above condition.

[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 Fifth lens group L6 Sixth lens group L7, 7th lens group L8, 8th lens group LR, rear group LIS, anti-shake group

Claims

1. A zoom lens in which a lens group arranged in order from the object side to the image side is composed of a first lens group having a positive refractive power, a second 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 distance between the first lens group and the second lens group increases, and the distance between the second lens group and the rear group increases, 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, the focal length of the first lens group is fL1, and the focal length of the second lens group is fL2, 4.4 ≦ D2t / D2w ≦ 15.0 -2.8 ≦ fL1 / fL2 ≦ 3.0 A zoom lens characterized by satisfying the following conditions.

2. 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.

3. 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 A zoom lens according to claim 1, characterized by satisfying the following conditions.

4. The rear group includes a third lens group on the most object side, 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 A zoom lens according to claim 1, characterized by satisfying the following conditions.

5. The rear group includes a third lens group on the object side most, 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 in that the condition is satisfied.

6. 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 in that the condition is satisfied.

7. The rear group includes a third lens group on the object side most, 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 in that the condition is satisfied.

8. When the back focus of the zoom lens at the wide-angle end is Skw, 0.03 ≦ Skw / fL1 ≦ 0.50 The zoom lens according to claim 1, characterized in that the condition is satisfied.

9. The rear group has a first focus lens group that moves during focusing 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 during focusing of the first focus lens group from an infinite object to a closest object at the telephoto end is MF1 and the movement 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 by satisfying the condition.

10. 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 by satisfying the condition.

11. 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 by satisfying the condition.

12. 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 by satisfying the condition.

13. 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 condition.

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

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

16. The zoom lens according to claim 1, wherein the third lens group is composed of four or fewer lenses.

17. The zoom lens according to claim 1, wherein the first focus lens group is composed of three or fewer lenses.

18. The zoom lens according to claim 1, wherein the second focus lens group is composed of three or fewer lenses.

19. The zoom lens according to claim 1, 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.

20. The rear group includes the third lens group on the most object side, The zoom lens according to claim 1, wherein the third lens group moves toward the image side when zooming from the wide-angle end to the telephoto end.

21. The rear group includes the third lens group on the most object side, and the rear group includes an aperture stop, The zoom lens according to claim 1, wherein the aperture stop moves independently of the third lens group when zooming.

22. The zoom lens according to claim 1, 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.

23. The zoom lens according to claim 1, wherein the lens groups constituting the zoom lens are, in order from the object side to the image side, a plurality of lens groups including 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.

24. The zoom lens according to claim 1, 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 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.

25. The zoom lens according to claim 1, 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 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.

26. The zoom lens according to claim 1, 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 positive 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 negative refractive power, and the eighth lens group having a positive refractive power.

27. The zoom lens according to any one of claims 1 to 26, and an imaging device having an imaging element that images a subject through the zoom lens.

28. A zoom lens in which a lens group arranged in order from the object side to the image side is composed of a first lens group having a positive refractive power, a second lens group, and a rear group including three or more lens groups, and the distance between adjacent lens groups changes during zooming, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the rear group increases, 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 a zoom lens characterized by satisfying the following conditions.

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