Zoom lens and imaging device

Abstract

[Problem] To provide a compact and lightweight zoom lens having high optical performance in the entire zoom range thereof. [Solution] In a zoom lens L0, lens groups arranged in order from the object side to the image side comprise a first lens group having a positive refractive power, a second lens group, and a rear group including a plurality of lens groups. During 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. 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 defined as D2w, the distance on the optical axis from the most object-side surface at the telephoto end to the most image-side surface 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. The expressions 4.4 ≤ D2t / D2w ≤ 15.0 and -2.8 ≤ fL1 / fL2 ≤ 3.0 are satisfied.

Description

Zoom lens and imaging device

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

[0002] Zoom lenses used for imaging include so-called positive-lead zoom lenses, which have high optical performance and meet the demand for small size and light weight, and in which a lens group with positive refractive power is arranged closest to the object.

[0003] Japanese Patent Application Laid-Open No. 2003-129999 discloses a zoom lens having a first lens group with positive refractive power arranged closest to the object, in which the spacing between adjacent lens groups changes during zooming.

[0004] JP 2022-92388 A

[0005] In general, to reduce the size of a zoom lens, it is effective to adopt a telephoto-type power arrangement at the telephoto end, strengthening the positive refractive power on the object side and the negative refractive power on the image side. However, strengthening the refractive power of each lens group increases the fluctuations in various aberrations that occur during zooming, making it difficult to effectively correct these aberrations with a small number of lenses. Furthermore, in positive-lead zoom lenses, the effective diameter of the object-side lens group is large, so the configuration of the object-side lens group is important for reducing weight. Therefore, to reduce the size and weight of a zoom lens, it is important to appropriately set both the refractive power of each lens group and the configuration of the object-side lens group.

[0006] The present invention provides a compact, lightweight zoom lens that has high optical performance over the entire zoom range.

[0007] In one aspect of the present invention, the zoom lens includes lens groups arranged in order from the object side to the image side: a first lens group having positive refractive power, a second lens group, and a rear group including multiple 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. The zoom lens is characterized by satisfying the following conditions: 4.4≦D2t / D2w≦15.0 −2.8≦fL1 / fL2≦3.0, where D2w is the axial distance from the most object-side surface of the zoom lens to the most image-side surface of the second lens group at the wide-angle end, D2t is the axial distance from the most object-side surface to the most image-side surface of the second lens group at the telephoto end, fL1 is the focal length of the first lens group, and fL2 is the focal length of the second lens group.

[0008] Another aspect of the present invention provides 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 positive refractive power, a second lens group, and a rear group including three or more lens groups, and the spacing between adjacent lens groups changes during zooming. When zooming from the wide-angle end to the telephoto end, the spacing between the first lens group and the second lens group increases, and the spacing between the second lens group and the rear group increases. When the axial distance from the most object-side surface of the zoom lens to the most image-side surface of the second lens group at the wide-angle end is D2w, and the axial distance from the most object-side surface to the most image-side surface of the second lens group at the telephoto end is D2t, the zoom lens satisfies the following condition: 4.4≦D2t / D2w≦15.0. An imaging device including the zoom lens also constitutes another aspect of the present invention.

[0009] According to the present invention, it is possible to provide a small and lightweight zoom lens that has high optical performance over the entire zoom range.

[0010] 1 is a cross-sectional view of a zoom lens of Example 1. 2 is aberration diagrams of the zoom lens of Example 1. 3 is a cross-sectional view of a zoom lens of Example 2. 4 is aberration diagrams of the zoom lens of Example 3. 5 is a cross-sectional view of a zoom lens of Example 4. 6 is a cross-sectional view of a zoom lens of Example 6. 7 is a schematic diagram of an imaging device equipped with the zoom lenses of Examples 1 to 6.

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

[0012] 1, 3, 5, 7, 9, and 11 show cross sections of the zoom lens L0 of Examples 1 to 6 at the wide-angle end and in a state where the lens is focused on an object at infinity (hereinafter referred to as the infinity-focused state). The zoom lens L0 of each Example is used in imaging devices such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras, as well as optical instruments including interchangeable lenses. It can also be used in optical instruments for observation, such as telescopes.

[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 in each embodiment has multiple lens groups, each with its own refractive power. In a zoom lens, a lens group is a group of one or more lenses that move as a unit during zooming between the wide-angle end and the telephoto end. That is, the spacing between adjacent lens groups changes during zooming. The lens groups may include an aperture stop. The wide-angle end and the telephoto end respectively represent the zoom states with the maximum angle of view (shortest focal length) and the minimum angle of view (maximum focal length) when the lens group that moves during zooming is positioned at both ends of the range of movement along the optical axis for mechanical or control reasons. Furthermore, the refractive power is the reciprocal of the focal length.

[0014] In each cross-sectional view, Li represents the ith lens group, counting from the object side, among the multiple lens groups included in the zoom lens L0. LR is a rear group including all lens groups arranged closer to the image side than the second lens group L2. LIS is an image stabilization group that moves in a direction including a directional component perpendicular to the optical axis and has the function of correcting image blur caused by camera shake or the like (image stabilization function). The image stabilization group may be an entire lens group, or a subgroup that is part of that lens group. The subgroup is a group of one or more lenses whose structural length (the distance from the lens surface closest to the object to the lens surface closest to the image in the subgroup) remains unchanged during zooming.

[0015] Furthermore, SP denotes an aperture stop. IP denotes an image plane. The image plane IP is provided with an imaging surface (light receiving surface) of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor, or a film surface (photosensitive surface) of a silver halide film. Note that an optical element such as a parallel plate or prism without refractive power, such as a low-pass filter or an infrared cut filter, may be disposed between the image plane IP and the lens of the zoom lens L0 that is positioned closest to the image side.

[0016] In each cross-sectional view, a solid arrow below the lens group that moves during zooming indicates the path of movement of that lens group during zooming from the wide-angle end to the telephoto end, and a dashed arrow below the focus lens group that moves during focusing indicates the direction of movement of that lens group during focusing from an object at infinity to a close object.

[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 located closer to the image side than the first focus lens group. The second focus lens group moves independently of the first focus lens group (i.e., moves along a different locus) during focusing.

[0018] First, we will explain the features common to the zoom lens L0 of each embodiment. The zoom lens L0 of each embodiment is a positive-lead zoom lens in which the refractive power of the first lens unit L1 is positive. In the zoom lens L0 of each embodiment, the lens units arranged in order from the object side to the image side are a first lens unit L1 with positive refractive power, a second lens unit L2, and a rear unit LR including multiple lens units. The rear unit LR is made up of all the lens units (the third lens unit L3 to the seventh lens unit L7 or the eighth lens unit L8) arranged closer to the image side than the second lens unit L2.

[0019] In the zoom lens L0 of each embodiment, when zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves, increasing the distance between the first lens unit L1 and the second lens unit L2, and increasing the distance between the second lens unit L2 and the rear unit LR, resulting in a telephoto-type power arrangement at the telephoto end, which is advantageous for shortening the overall length of the zoom lens L0.

[0020] In general, the longer the focal length of a zoom lens at the telephoto end, the greater the chromatic aberration tends to be, and the larger the first lens group with positive refractive power tends to be. This is because the closer a lens is to the object at the telephoto end, the higher the incidence height of axial light rays, resulting in a larger effective diameter (the radius of the area through which light rays contributing to image formation pass). From the perspective of correcting chromatic aberration, it is preferable to position multiple positive lenses made of low-dispersion materials closer to the object. However, from the perspective of weight reduction, it is preferable to reduce the effective diameter of the lenses positioned closer to the object and minimize the number of lenses positioned closer to the object. This is because the volume (mass) of a lens is approximately proportional to the cube of the effective diameter.

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

[0022] 4.4≦D2t / D2w≦15.0 (1) −2.8≦fL1 / fL2≦3.0 (2) The condition in formula (1) indicates an appropriate relationship between the optical axial distance D2w from the surface closest to the object (foreground) of the zoom lens L0 at the wide-angle end to the surface closest to the image in the second lens unit L2, and the optical axial distance D2t from the background surface to the surface closest to the image in the second lens unit L2 at the telephoto end. By satisfying the condition in formula (1), the total thickness of the first lens unit L1 and the second lens unit L2 can be reduced at the wide-angle end, and the effective diameter of the second lens unit L2 can be reduced at the telephoto end, facilitating weight reduction of the zoom lens. If the distance D2t becomes too small, such that D2t / D2w falls below the lower limit of formula (1), the effective diameter of the second lens unit L2 becomes large, making it difficult to reduce the weight of the zoom lens L0, which is undesirable. If the distance D2t becomes too large so that D2t / D2w exceeds the upper limit of the formula (1), it becomes difficult to reduce the size of the zoom lens L0 at the telephoto end, which is not preferable.

[0023] The condition of formula (2) indicates an appropriate relationship between the focal length fL1 of the first lens unit L1 and the focal length fL2 of the second lens unit L2. By satisfying the condition of formula (2), the refractive power of the first lens unit L1 becomes strong, making it easier to correct chromatic aberration at the telephoto end. If the focal length fL1 of the first lens unit L1 becomes too long (refractive power becomes weak) so that fL1 / fL2 exceeds the upper limit value or falls below the lower limit value of formula (2), it becomes difficult to correct chromatic aberration at the telephoto end, which is not preferable.

[0024] It is more preferable that the numerical ranges of the formulas (1) and (2) be as follows:

[0025] 4.5≦D2t / D2w≦14.0 (1a) −2.0≦fL1 / fL2≦2.0 (2a) Furthermore, it is more preferable to set the numerical ranges of the formulas (1) and (2) 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 compact and lightweight zoom lens L0 is obtained that has high optical performance over the entire zoom range.

[0027] It is also preferable that the zoom lens L0 of each embodiment satisfies at least one of the conditions of the following expressions (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 in equation (3) indicates the appropriate relationship between the movement amount ML1 of the first lens unit L1 during zooming from the wide-angle end to the telephoto end and the total optical length TLw of the zoom lens L0 at the wide-angle end. The movement amount of a lens unit during zooming from the wide-angle end to the telephoto end is the difference in the optical axial position of the lens unit at the wide-angle end and the telephoto end, and does not include the amount of reciprocating movement. The sign of the movement amount is positive when the lens unit is located closer to the image at the telephoto end than at the wide-angle end. The total optical length TLw is the distance on the optical axis from the forefront of the zoom lens L0 to the image plane IP. If the movement amount ML1 of the first lens unit L1 becomes too small so that |ML1 / TLw| falls below the lower limit of equation (3), it becomes difficult to ensure a high zoom ratio, which is undesirable. If the movement amount ML1 of the first lens unit L1 becomes too large so that |ML1 / TLw| exceeds the upper limit of the formula (3), it becomes difficult to reduce the size of the zoom lens L0 at the telephoto end, which is not preferable.

[0029] The condition of formula (4) indicates the appropriate relationship between the movement amount ML3 of the third lens unit L3, which is located closest to the object in the rear lens group LR, during zooming from the wide-angle end to the telephoto end, and the total optical length TLw of the zoom lens L0 at the wide-angle end. If the movement amount ML3 of the third lens unit L3 becomes too small so that |ML3 / TLw| falls below the lower limit of formula (4), it becomes difficult to ensure a high zoom ratio, which is undesirable. On the other hand, if the movement amount ML3 of the third lens unit L3 becomes too large so that |ML3 / TLw| exceeds the upper limit of formula (4), it becomes difficult to reduce the size of the zoom lens L0 at the wide-angle end, which is undesirable.

[0030] The condition of equation (5) indicates an appropriate relationship between the movement amount ML1 of the first lens unit L1 and the movement amount ML3 of the third lens unit L3 during zooming from the wide-angle end to the telephoto end. If the movement amount ML1 of the first lens unit L1 becomes too small so that |ML3 / ML1| falls below the lower limit of equation (5), it becomes difficult to ensure a high zoom ratio, which is undesirable. If the movement amount ML1 of the first lens unit L1 becomes too large so that |ML3 / ML1| exceeds the upper limit of equation (5), it becomes difficult to reduce the size of the zoom lens L0 at the telephoto end, which is undesirable.

[0031] The condition of formula (6) indicates an appropriate relationship between the amount of movement ML2 of the second lens unit L2 and the amount of movement ML1 of the first lens unit L1 during zooming from the wide-angle end to the telephoto end. If the amount of movement ML2 of the second lens unit L2 becomes too large so that |ML2 / ML1| exceeds the upper limit of formula (6), it becomes difficult to reduce the size of the zoom lens L0 at the wide-angle end, which is not preferable.

[0032] The condition of expression (7) indicates an appropriate relationship between the movement amount ML2 of the second lens unit L2 and the movement amount ML3 of the third lens unit L3 during zooming from the wide-angle end to the telephoto end. If the movement amount ML2 of the second lens unit L2 becomes too large so that |ML2 / ML3| exceeds the upper limit of expression (7), it becomes difficult to reduce the size of the zoom lens L0 at the wide-angle end, which is not preferable.

[0033] The condition of equation (8) indicates an appropriate relationship between the back focal length Skw of the zoom lens L0 at the wide-angle end and the focal length fL1 of the first lens unit L1. If the back focal length Skw at the wide-angle end is too short, such that Skw / fL1 falls below the lower limit of equation (8), it becomes difficult to arrange optical elements such as a low-pass filter near the image plane IP where the imaging surface of the image sensor is located, which is undesirable. If the back focal length Skw is too long, such that Skw / fL1 exceeds the upper limit of equation (8), the total optical length of the zoom lens L0 at the wide-angle end becomes long, making it difficult to achieve compactness, which is undesirable.

[0034] The condition of equation (9) indicates the appropriate relationship between the movement amount MF1 of the first focus lens group at the telephoto end when focusing from an object at infinity to a close object and the movement amount MF2 of the second focus lens group at the telephoto end when focusing from an object at infinity to a close object. The movement amount of the focus lens group when focusing from an object at infinity to a close object is the difference between the positions on the optical axis where the focus lens group focuses on the object at infinity and the close object, respectively, and does not include the amount of reciprocating movement. Furthermore, the sign of the movement amount when the position where the focus lens group focuses on the close object is closer to the object than the position where the focus lens group focuses on the object at infinity is positive. If the movement amount MF1 of the first focus lens group becomes too small so that |MF1 / MF2| falls below the lower limit of equation (9), it becomes difficult to suppress fluctuations in spherical aberration and other aberrations during focusing, which is undesirable. Furthermore, if the movement amount MF1 of the first focus lens group becomes too large so that |MF1 / MF2| exceeds the upper limit value of equation (9), fluctuations in spherical aberration and other aberrations during focusing will increase, which is undesirable.

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

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

[0037] The condition of formula (12) indicates an appropriate range for the average value νdL2Nave. of the Abbe numbers, based on the d-line, of all negative lenses included in at least one negative lens in the second lens unit L2. If νdL2Nave. is below the lower limit of formula (12), it becomes difficult to correct lateral chromatic aberration at the wide-angle end, which is undesirable. If νdL2Nave. is above the upper limit of formula (12), it becomes difficult to correct axial chromatic aberration and lateral chromatic aberration at the telephoto end, which is undesirable.

[0038] The condition of formula (13) indicates an appropriate range for the refractive index ndG1 at the d-line of the positive lens G1 closest to the object in the first lens unit L1. If ndG1 is below the lower limit of formula (13), the curvature of the surface becomes large in order to obtain the necessary refractive power, which is undesirable because high-order spherical aberration occurs. If ndG1 is above the upper limit of formula (13), although this is advantageous for reducing the size of the first lens unit L1, the refractive power becomes too strong, making it difficult to correct distortion aberration while correcting spherical aberration, which is undesirable.

[0039] It is more preferable to set the numerical ranges of the formulas (3) to (13) 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) Furthermore, it is more preferable to set the numerical ranges of the formulas (3) to (13) 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, the configuration that the zoom lens L0 of each example preferably satisfies will be described.

[0042] The first lens group L1 is preferably composed of two or less single lenses, which makes it easier to reduce the weight of the first lens group L1. Note that if there is a cemented lens in which multiple (e.g., two) lenses are cemented together, the term "first lens group L1" is used to refer to the multiple (two) lenses included in the first lens group L1.

[0043] The second lens group L2 is preferably composed of three or fewer lenses, which makes it easier to reduce the weight of the second lens group L2. The third lens group L3 is preferably composed of four or fewer lenses, which makes it even easier to reduce the weight of the third lens group L3.

[0044] The first focus lens group is preferably composed of three or less lenses, which makes it easier to reduce the weight of the first focus lens group. The second focus lens group is preferably composed of three or less lenses, which makes it easier to reduce the weight of the second focus lens group.

[0045] The rear group LR preferably includes an image stabilizing group. By using a part or subgroup of the rear group LR as an image stabilizing group, the diameter of the image stabilizing group can be reduced, making it easier to make the zoom lens more compact.

[0046] It is preferable that the rear group LR includes three or more lens groups, and the spacing between adjacent lens groups changes during zooming. It is even more preferable that the rear group LR includes four or more lens groups, and the spacing between adjacent lens groups changes during zooming. By moving many lens groups during zooming, it is possible to suppress aberration fluctuations during zooming and easily ensure a high zoom ratio.

[0047] It is preferable that the third lens unit L3 move toward the image side during zooming from the wide-angle end to the telephoto end. By positioning the third lens unit L3 on the image side at the telephoto end, it becomes easy to reduce the diameter and weight of the third lens unit L3.

[0048] It is preferable that the aperture stop SP moves independently of (i.e., along a different locus from) the third lens unit L3 during zooming, which makes it easier to reduce the diameter of the aperture stop SP and further makes it easier to reduce the size of the zoom lens L0.

[0049] Next, the configuration of the zoom lens L0 of each embodiment will be described in detail. The zoom lens L0 of each embodiment is composed of a first lens unit L1, a second lens unit L2 with negative refractive power, a third lens unit L3 with positive refractive power, a fourth lens unit L4 with negative refractive power, a fifth lens unit L5 with positive refractive power, a sixth lens unit L6 with positive refractive power, and a seventh lens unit L7 with negative refractive power. The fourth lens unit L4 to the seventh lens unit L7 are included in the rear unit LR. An aperture stop SP is located closest to the object in the fifth lens unit L5.

[0050] In the zoom lens L0 of Examples 1 and 2, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side, the second lens unit L2 does not move, and the third lens unit L3 and the fourth lens unit L4 move toward the image side. Furthermore, the fifth to seventh lens units L5 to L7 move toward the object side. During focusing from an object at infinity to a close distance, the fourth lens unit L4 moves toward the object side as the first focus lens unit, and the seventh lens unit L7 moves toward the image side as the second focus lens unit.

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

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

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

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

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

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

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

[0058] In the zoom lens L0 of Example 6, during zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side, the second lens unit L2 does not move, and the third lens unit L3 moves toward the image side. The fourth to seventh lens units L4 to L7 move toward the object side, and the eighth lens unit L8 does not move. During focusing from an object at infinity to a close distance, the fifth lens unit L5 moves toward the image side as the first focus lens unit, and the seventh lens unit L7 moves toward the image side as the second focus lens unit.

[0059] Numerical Examples 1 to 6 corresponding to Examples 1 to 6, respectively, are shown below. In the surface data of each numerical example, 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 at the d-line of the optical material between the i-th surface and the (i+1)-th surface. 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 half angle of view (°) are all values ​​when focused at infinity. BF represents back focus (mm). Back focus is the distance on the optical axis from the surface of the zoom lens closest to the image (final surface) to the paraxial image plane, expressed as an air-equivalent length. The total lens length is the distance on the optical axis from the front surface to the final surface of the zoom lens plus the back focus, and corresponds to the total optical length.

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

[0062] X = (h 2 / R) / [1+[1-(1+K)(h / R) 2 ] 1 / 2 ]+A4×h 4 + A6 x h 6 +A8 x h 8 + A10 x h 10 + A12 x h 12 + A14 x h 14 The values ​​relating to 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] 2, 4, 6, 8, 10, and 12 respectively show longitudinal aberrations (spherical aberration, astigmatism, distortion, and chromatic aberration) of the zoom lens L0 of Numerical Examples 1 to 6 in (A) a state where the zoom lens is at the wide-angle end and focused at infinity, and in (B) a state where the zoom lens is at the wide-angle end and focused on an object at a close distance (hereinafter referred to as a close-up focused state). Also, Figures 3, 6, 9, 12, 15, and 18 respectively show longitudinal aberrations of the zoom lens L0 of Numerical Examples 1 to 6 in (A) a state where the zoom lens is at the telephoto end and focused at infinity, and in (B) a state where the zoom lens is at the telephoto end and focused on a close-up.

[0064] In the spherical aberration diagram, Fno indicates the F-number, the solid line indicates the spherical aberration for the d-line (wavelength 587.6 nm), and the two-dot chain line indicates the spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line ΔS indicates the astigmatism at the sagittal image plane, and the dashed line ΔM indicates the astigmatism at the meridional image plane. The distortion diagram shows distortion at the d-line. The chromatic aberration diagram shows chromatic aberration of magnification at the g-line. ω is the half angle of view (°), which indicates the angle of view calculated by paraxial calculation. [Numerical example 1] Unit: mm Surface data Surface number rd 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 ∞ Aspheric data Surface 24 K = 0.00000e+00 A4= 7.41455e-06 A6= 2.87737e-09 A8=-2.41337e-11 A10= 1.40485e-13 A12=-2.80246e-16 Surface 36 K = 0.00000e+00 A4=-3.89934e-06 A6=-1.16405e-08 A8= 2.43384e-10 A10=-2.46472e-12 A12= 9.07277e-15 Data Zoom Ratio 4.70 Wide-angle Mid-range Telephoto Focal Length 103.18 203.65 484.84 F-Number 4.63 5.35 6.43 Half Angle of View (°) 11.84 6.06 2.56 Image Height 21.64 21.64 21.64 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 Initial 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 rd 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 surface ∞ Aspheric data Surface 21 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 Surface 35 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 36th side 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 Mid-range Telephoto Focal length 103.03 205.48 484.97 F-number 4.63 5.35 6.43 Half angle of view (°) 11.86 6.01 2.55 Image height 21.64 21.64 21.64 Total 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 Initial 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 rd 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 ∞ Aspheric data Surface 28 K = 0.00000e+00 A4= 6.76027e-07 A6= 2.49893e-09 A8=-2.91480e-11 A10= 1.94933e-13 A12=-4.85325e-16 Other data Zoom ratio 5.66 Wide-angle Mid-range Telephoto Focal length 103.31 199.40 584.79 F-number 4.63 5.65 6.49 Half angle of view (°) 11.83 6.19 2.12 Image height 21.64 21.64 21.64 Total lens length 284.16 346.98 389.09 BF 37.71 39.02 78.98 d 2 0.90 63.72 105.83 d 6 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 Initial 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 rd 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 surface ∞ Aspheric data Surface 31 K = 0.00000e+00 A4= 1.15289e-06 A6=-5.59256e-10 A8= 1.61123e-11 A10=-4.37103e-14 A12=-1.07538e-16 Other data Zoom ratio 5.68 Wide angle Mid-range Telephoto Focal length 103.05 193.32 584.97 F-number 4.64 5.65 6.49 Half angle of view (°) 11.86 6.39 2.12 Image height 21.64 21.64 21.64 Total 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 Initial 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 rd 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 ∞ Aspheric data Surface 33 K = 0.00000e+00 A4= 1.40271e-06 A6=-2.47421e-10 A8= 1.80038e-11 A10=-1.20178e-13 A12= 2.66081e-16 Other data Zoom ratio 4.71 Wide-angle Mid-range Telephoto Focal length 103.01 175.25 484.99 F-number 4.63 5.65 6.49 Half angle of view (°) 11.86 7.04 2.55 Image height 21.64 21.64 21.64 Total 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 Initial 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 rd 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 ∞ Aspheric data Surface 21 K = 0.00000e+00 A4= 3.06078e-06 A6= 1.73892e-10 A8= 6.89073e-12 A10=-4.56144e-14 A12= 1.05385e-16 Surface 27 K = 0.00000e+00 A4= 2.47584e-06 A6= 5.75349e-09 A8=-5.56712e-11 A10= 4.81095e-13 A12=-1.44822e-15 Various data Zoom ratio 4.70 Wide-angle Mid-range Telephoto Focal length 103.24 201.65 484.75 F-number 4.63 5.35 6.43 Half angle of view (°) 11.84 6.12 2.56 Image height 21.64 21.64 21.64 Total lens length 238.68 290.83 336.09 BF 46.01 46.01 46.01 d 2 0.90 53.04 98.31 d 5 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 Initial 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]

[0066] 13 shows an imaging device (digital still camera) 10 that uses, as an imaging optical system, the zoom lens L0 of Examples 1 to 6. The imaging device 10 has a camera body 13, a zoom lens 11 (L0) of any one of Examples 1 to 6, and an image sensor 12 that photoelectrically converts an optical image formed by the zoom lens 11 (to capture an image of a subject).

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

[0068] [Imaging System] An imaging system, such as a surveillance camera system, may be configured that includes the zoom lens L0 of each embodiment and a control unit that controls the zoom lens L0. 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 vibration isolation. In this case, the control unit does not need to be configured integrally with the zoom lens L0; the control unit may be configured separately from the zoom lens L0. For example, a configuration may be adopted in which a control device serving as a control unit, located remotely from the drive units that drive each lens of the zoom lens L0, includes a transmission unit that sends control signals (commands) to control the zoom lens L0. Such a control unit allows the zoom lens L0 to be remotely controlled.

[0069] Alternatively, the control unit may be provided with an operation unit such as a controller or buttons for remotely operating the zoom lens L0, thereby controlling the zoom lens L0 in response to a user's input to the operation unit. For example, the operation unit may be provided with a zoom button and a zoom-in button. In this case, the control unit may be configured to send a signal to a drive unit for the zoom lens L0 so that when the user presses the zoom-in button, the magnification of the zoom lens L0 increases, and when the user presses the zoom-out button, the magnification of the zoom lens L0 decreases.

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

[0071] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention.

Claims

1. A zoom lens in which the lens groups arranged in order from the object side to the image side consist of a first lens group having 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, 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, and wherein, when the distance on the optical axis from the surface closest to the object of the zoom lens at the wide-angle end to the surface closest to the image of the second lens group is D2w, the distance on the optical axis from the surface closest to the object to the surface closest to the image 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, the following conditions are satisfied: 4.4≦D2t / D2w≦15.0 -2.8≦fL1 / fL2≦3.

0.

2. The zoom lens according to claim 1, wherein the rear group includes three or more lens groups, and the spacing between adjacent lens groups in the rear group changes during zooming.

3. The zoom lens according to claim 1 or 2, characterized in that it satisfies the condition: 0.15≦|ML1 / TLw|≦0.90, where ML1 is the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end, and TLw is the total optical length of the zoom lens at the wide-angle end.

4. A zoom lens according to any one of claims 1 to 3, characterized in that the rear group includes a third lens group closest to the object, and satisfies the condition: 0.05≦|ML3 / TLw|≦0.40, where ML3 is the amount of movement of the third lens group during zooming from the wide-angle end to the telephoto end, and TLw is the total optical length of the zoom lens at the wide-angle end.

5. A zoom lens according to any one of claims 1 to 4, characterized in that the rear group includes a third lens group closest to the object, and satisfies the condition: 0.05≦|ML3 / ML1|≦0.80, where ML1 is the amount of movement of the first lens group when zooming from the wide-angle end to the telephoto end, and ML3 is the amount of movement of the third lens group when zooming from the wide-angle end to the telephoto end.

6. A zoom lens according to any one of claims 1 to 5, characterized in that, when the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end is ML2 and the amount of movement of the first lens group during zooming from the wide-angle end to the telephoto end is ML1, the zoom lens satisfies the condition |ML2 / ML1|≦0.

20.

7. A zoom lens according to any one of claims 1 to 6, characterized in that the rear group includes a third lens group closest to the object, and satisfies the condition |ML2 / ML3|≦0.40, where ML2 is the amount of movement of the second lens group during zooming from the wide-angle end to the telephoto end, and ML3 is the amount of movement of the third lens group during zooming from the wide-angle end to the telephoto end.

8. The zoom lens according to any one of claims 1 to 7, wherein the following condition is satisfied: 0.03≦Skw / fL1≦0.50, where Skw is the back focus of the zoom lens at the wide-angle end.

9. A zoom lens according to any one of claims 1 to 8, characterized in that the rear group has a first focus lens group that moves during focusing, and a second focus lens group that is located closer to the image than the first focus lens group and moves during focusing, and where the amount of movement of the first focus lens group when focusing from an object at infinity to an object at a close distance at the telephoto end is MF1 and the amount of movement of the second focus lens group when focusing from an object at infinity to an object at a close distance at the telephoto end is MF2, the zoom lens satisfies the condition: 0.20≦|MF1 / MF2|≦5.

00.

10. The zoom lens according to any one of claims 1 to 9, wherein the first lens group includes at least one positive lens, and satisfies the condition: 60≦νdL1Pave. ≦99, where νdL1Pave. is the average Abbe number of all positive lenses included in the first lens group with respect to the d-line.

11. The zoom lens according to any one of claims 1 to 10, characterized in that the second lens group includes at least one positive lens, and satisfies the condition: 60≦νdL2Pave. ≦99, where νdL2Pave. is the average Abbe number of all positive lenses included in the second lens group with respect to the d-line.

12. The zoom lens according to any one of claims 1 to 11, characterized in that the second lens group includes at least one negative lens, and satisfies the following condition: 20≦νdL2Nave.≦45, where νdL2Nave. is the average Abbe number of all negative lenses included in the second lens group with respect to the d-line.

13. A zoom lens according to any one of claims 1 to 12, characterized in that the first lens group includes at least one positive lens, and when the refractive index at the d-line of the positive lens located closest to the object among the at least one positive lens is ndG1, the following condition is satisfied: 1.40≦ndG1≦1.

70.

14. A zoom lens according to any one of claims 1 to 13, characterized in that the first lens group is composed of two or less single lenses.

15. The zoom lens according to any one of claims 1 to 14, wherein the second lens group is composed of three or less lenses.

16. The zoom lens according to any one of claims 1 to 15, wherein the third lens group is composed of four or less lenses.

17. A zoom lens according to any one of claims 1 to 16, characterized in that the first focus lens group is composed of three or less lenses.

18. A zoom lens according to any one of claims 1 to 17, characterized in that the second focus lens group is composed of three or less lenses.

19. A zoom lens according to any one of claims 1 to 18, characterized in that at least a part of one of the lens groups included in the rear group is an image stabilization group that moves relative to the optical axis to reduce image blur.

20. A zoom lens according to any one of claims 1 to 19, characterized in that the rear group includes a third lens group closest to the object side, and the third lens group moves towards the image side during zooming from the wide-angle end to the telephoto end.

21. A zoom lens according to any one of claims 1 to 20, characterized in that the rear group includes a third lens group closest to the object, the rear group includes an aperture diaphragm, and the aperture diaphragm moves independently of the third lens group during zooming.

22. A zoom lens according to any one of claims 1 to 21, characterized in that the lens groups constituting the zoom lens consist of, arranged in order from the object side to the image side, the first lens group, the second lens group having negative refractive power, the third lens group having positive refractive power, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, a sixth lens group having positive refractive power, and a seventh lens group having negative refractive power.

23. A zoom lens according to any one of claims 1 to 21, characterized in that the lens groups constituting the zoom lens are a plurality of lens groups arranged in order from the object side to the image side, comprising the first lens group, the second lens group having negative refractive power, the third lens group having negative refractive power, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, a seventh lens group having positive refractive power, and an eighth lens group having negative refractive power.

24. A zoom lens according to any one of claims 1 to 21, characterized in that the lens groups constituting the zoom lens consist of, arranged in order from the object side to the image side, the first lens group, the second lens group having positive refractive power, the third lens group having positive refractive power, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, a seventh lens group having positive refractive power, and an eighth lens group having negative refractive power.

25. A zoom lens according to any one of claims 1 to 21, characterized in that the lens groups constituting the zoom lens consist of, arranged in order from the object side to the image side, the first lens group, the second lens group having positive refractive power, the third lens group having negative refractive power, a fourth lens group having negative refractive power, a fifth lens group having positive refractive power, a sixth lens group having negative refractive power, a seventh lens group having positive refractive power, and an eighth lens group having negative refractive power.

26. A zoom lens according to any one of claims 1 to 21, characterized in that the lens groups constituting the zoom lens consist of, arranged in order from the object side to the image side, the first lens group, the second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, a sixth lens group having positive refractive power, a seventh lens group having negative refractive power, and an eighth lens group having positive refractive power.

27. An imaging device comprising: a zoom lens according to any one of claims 1 to 26; and an imaging element for capturing an image of a subject through said zoom lens.

28. A zoom lens in which the lens groups arranged in order from the object side to the image side consist of a first lens group having 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, and where the distance on the optical axis from the surface closest to the object of the zoom lens at the wide-angle end to the surface closest to the image of the second lens group is D2w, and the distance on the optical axis from the surface closest to the object to the surface closest to the image of the second lens group at the telephoto end is D2t, the zoom lens satisfies the condition: 4.4≦D2t / D2w≦15.0.

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