Optical system and imaging apparatus

Abstract

To reduce the size and weight of a movable group that is eccentric to an optical axis, and prevent the occurrence of chromatic aberration caused by the movable group.SOLUTION: An optical system 1a is composed of a plurality of lens groups L1-L7, and any of the lens groups has a movable group IS movable in a direction eccentric to an optical axis. The movable group includes a cemented lens obtained by joining a resin layer rep having a refractive power and a base material lens to each other. When the focal distance of the resin layer is fr, and the focal distance of the movable group is fis, the condition of -0.95≤fis / fr<0 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system having a movable group that is movable in a direction decentered relative to an optical axis. [Background technology]

[0002] In an optical system used in an imaging device, moving (shifting) a lens or lens group serving as an image stabilization group in a direction eccentric to the optical axis can reduce (correct) image blur caused by camera shake or other causes in the image stabilization group. Patent Documents 1 and 2 disclose optical systems in which a portion of an intermediate lens group is shifted in a direction perpendicular to the optical axis as an image stabilization group. Specifically, Patent Document 1 discloses a positive-lead zoom lens system having first to fifth lens groups arranged in order from the object side to the image side as positive, negative, positive, negative, and positive lens groups, in which the entire third lens group serves as an image stabilization group. Patent Document 2 also discloses a positive-lead zoom lens system having first to seventh lens groups arranged in order from the object side to the image side as positive, negative, positive, negative, positive, negative, and positive lens groups, in which the entire fourth lens group, consisting of a cemented lens formed by cementing two negative lenses, serves as an image stabilization group. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-106681 [Patent Document 2] Japanese Patent Publication No. 2020-086331 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the optical system disclosed in Patent Document 1, the third lens group, which is an image stabilization group, is composed of four lenses arranged in order from the object side: positive, negative, positive, and negative, and is therefore heavy. This requires a large drive mechanism for shifting the entire third lens group relative to the optical axis, which results in a large lens barrel housing the imaging optical system. Furthermore, in the imaging optical system disclosed in Patent Document 2, the fourth lens group, which is an image stabilization group, is composed of two lenses, which makes it small and lightweight, but makes it difficult to suppress chromatic aberration when the fourth lens group is shifted.

[0005] The present invention provides an optical system and an imaging device that can reduce the size and weight of a movable group that is decentered with respect to the optical axis, while also suppressing the occurrence of chromatic aberration due to the movable group. [Means for solving the problem]

[0006] An optical system according to one aspect of the present invention has a movable group that is movable in a direction decentered relative to an optical axis, the movable group comprising a resin layer and one lens that are bonded together, wherein the focal length of the resin layer is fr and the focal length of the movable group is fis, -0.95≦fis / fr<0 The optical system is characterized by satisfying the following conditions: Note that an imaging device having the optical system described above also constitutes another aspect of the present invention. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the size and weight of a movable group that is decentered with respect to the optical axis, while also suppressing the occurrence of chromatic aberration due to the movable group. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment at a wide-angle end. [Figure 2] 1A to 1C are longitudinal aberration diagrams of the zoom lens of Example 1 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 3]4A to 4C are lateral aberration diagrams of the zoom lens of Example 1 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 4] 1A and 1B are lateral aberration diagrams of the zoom lens of Example 1 at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end with 0.3 degree image stabilization. [Figure 5] FIG. 10 is a cross-sectional view of the zoom lens of the second embodiment at the wide-angle end. [Figure 6] 10A to 10C are longitudinal aberration diagrams of the zoom lens of Example 2 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 7] 10A to 10C are lateral aberration diagrams of the zoom lens of Example 2 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 8] 10A and 10B are lateral aberration diagrams of the zoom lens of Example 2 at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end with 0.3 degree image stabilization. [Figure 9] FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment at a wide-angle end. [Figure 10] 10A to 10C are longitudinal aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 11] 10A to 10C are lateral aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 12] 10A and 10B are lateral aberration diagrams of the zoom lens of Example 3 at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end with 0.3 degree image stabilization. [Figure 13] FIG. 10 is a cross-sectional view of a single focal length lens according to a fourth embodiment. [Figure 14] FIG. 10 is a longitudinal aberration diagram of the single focal length lens of Example 4. [Figure 15] 10A and 10B are diagrams showing lateral aberration of the single focal length lens of Example 4. [Figure 16] 10A and 10B are diagrams showing lateral aberrations of the zoom lens of Example 4 when image stabilization is performed at 0.3 degrees. [Figure 17] FIG. 10 is a cross-sectional view of a zoom lens at a wide-angle end according to a fifth embodiment. [Figure 18] 10A to 10C are longitudinal aberration diagrams of the zoom lens of Example 5 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 19]10A to 10C are lateral aberration diagrams of the zoom lens of Example 5 at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. [Figure 20] 10A and 10B are lateral aberration diagrams of the zoom lens of Example 5 at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end with 0.3 degree image stabilization. [Figure 21] 1A and 1B are diagrams showing an imaging device equipped with lenses according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] First, before describing specific examples, matters common to all examples will be described. The optical system in each example has multiple lens groups. In each example, a lens group is composed of a single lens or multiple lenses. The spacing between adjacent lens groups changes during at least one of zooming and focusing. One of the lens groups is an image stabilization group that serves as a movable group that moves (shifts) in a direction (decentering direction) that includes a component perpendicular to the optical axis to reduce (correct) image blur. The image stabilization group includes a cemented lens formed by cementing (adhering) a resin layer having refractive power to a base lens.

[0011] The vibration reduction group may also rotate around a rotation center on the optical axis in a direction that includes a component perpendicular to the optical axis. That is, the vibration reduction group may move in a direction that is eccentric with respect to the optical axis. Furthermore, although each embodiment describes a case in which the movable group is moved to correct image shake, the movable group may also be moved for purposes other than image shake correction, such as tilted photography or tracking a moving subject during moving subject imaging.

[0012] The optical systems of Examples 1 to 3 and Example 5 are zoom lenses with variable focal lengths, while the optical system of Example 4 is a fixed focal length lens. In a zoom lens, a lens group is a group of one or more lenses that move together during zooming between the wide-angle end and the telephoto end. That is, the spacing between adjacent lens groups changes during zooming. The lens group may include an aperture stop. The wide-angle end and the telephoto end refer to zoom states with the maximum angle of view (minimum 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 on the optical axis for mechanical or control reasons. In a fixed focal length lens, a lens group refers to a group of lenses separated before and after an aperture stop, or a group of lenses that moves, such as an image stabilization group, and a group of lenses separated before and after the aperture stop. Specific numerical examples 1 to 5 corresponding to Examples 1 to 5, respectively, are described below.

[0013] FIGS. 1, 5, 9, and 17 show cross sections of zoom lenses 1a, 1b, 1c, and 1d of Examples 1 to 3 and Example 5 at the wide-angle end in an infinity-focused state. The zoom lens 1a of Example 1 (Numerical Example 1) has a zoom ratio of 4.7x and an F-number of approximately 2.9. The zoom lens 1a has a half angle of view of 37 degrees at the wide-angle end and an 11 degree half angle of view at the telephoto end. The zoom lens 1b of Example 2 (Numerical Example 2) has a zoom ratio of 4.7x and an F-number of approximately 2.9. The zoom lens 1b has a half angle of view of 37 degrees at the wide-angle end and an 11 degree half angle of view at the telephoto end. The zoom lens 1c of Example 3 (Numerical Example 3) has a zoom ratio of 4.7x and an F-number of approximately 2.9. The zoom lens 1c has a half angle of view of 37 degrees at the wide-angle end and an 11 degree half angle of view at the telephoto end. The zoom lens 1e of Example 5 (Numerical Example 5) has a zoom ratio of 3.8 and an F-number of approximately 4.6 to 7.3. The zoom lens 1e has a half angle of view of 12 degrees at the wide-angle end and 3 degrees at the telephoto end.

[0014] FIGS. 2, 6, 10, and 18 (A), (B), and (C) show longitudinal aberrations at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lenses 1a, 1b, 1c, and 1d of Examples 1 to 3 and Example 5, respectively. FIGS. 3, 7, 11, and 19 (A), (B), and (C) show lateral aberrations at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lenses 1a, 1b, 1c, and 1d, respectively. FIGS. 4, 8, 12, and 20 (A), (B), and (C) show lateral aberrations at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lenses 1a, 1b, 1c, and 1d, respectively, with the image stabilization group shifted to a position that corrects angular shake of 0.3 degrees.

[0015] Moreover, Fig. 13 shows a cross section of the fixed focal length lens of Example 4 in a state focused at infinity. The F-number of the fixed focal length lens 1d of Example 4 (Numerical Example 4) is approximately 1.45, and the half angle of view is 15 degrees. Figs. 13 and 14 respectively show the longitudinal aberration and lateral aberration of the fixed focal length lens of Example 4. Fig. 15 shows the lateral aberration in the fixed focal length lens of Example 4 when the image stabilization group is shifted to a position that corrects angular shake of 0.3 degrees.

[0016] The lenses 1a to 1e are used as imaging optical systems in imaging devices such as digital cameras, video cameras, broadcast cameras, surveillance cameras, silver halide film cameras, etc. The lenses 1a to 1e can also be used as projection optical systems in image projection devices (projectors).

[0017] In Figures 1, 5, 9, 13, and 17, the left side is the object side (front side) and the right side is the image side (rear side). Li (i = 1, 2, ...) indicates the i-th lens group counting from the object side. IS indicates the vibration isolation group. Grep indicates the resin layer. SP indicates the aperture stop (aperture group). IP indicates the image plane. The imaging surface of a solid-state imaging device (photoelectric conversion element) such as a CCD sensor or CMOS sensor, or the film surface of a silver halide film, is located on the image plane IP. In Figures 1, 5, 9, and 17, arrows indicate the movement trajectories of the lens groups and aperture stop SP that move during zooming from the wide-angle end to the telephoto end. The arrow labeled "FOCUS" indicates the direction of movement of the lens groups during focusing from an object at infinity to a close-up object.

[0018] In the spherical aberration diagrams of Figures 2, 6, 6, 10, and 18, Fno indicates the F-number, the solid line indicates spherical aberration for the d-line (wavelength 587.6 nm), and the two-dot chain line indicates spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagrams, the solid line S indicates the sagittal image plane for the d-line, and the dashed line M indicates the meridional image plane for the d-line. The distortion diagrams show distortion for the d-line. The chromatic aberration diagrams show lateral chromatic aberration for the g-line. ω is the half angle of view (°).

[0019] The lens configuration of each example will be described below.

[0020] The zoom lens 1a of Example 1 shown in FIG. 1 is a seven-group zoom lens that is composed of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, a sixth lens group L6 with negative refractive power, and a seventh lens group L7 with positive refractive power.

[0021] During zooming from the wide-angle end to the telephoto end, the first lens group L1 moves toward the object side, and the second lens group L2 moves toward the image side and then moves toward the object side. The third lens group L3 moves toward the object side, and the fourth lens group L4 moves toward the object side to reduce the distance between it and the third lens group L3. The fifth lens group L5 moves toward the object side to reduce the distance between it and the fourth lens group L4 and then move toward the object side. The sixth lens group L6 moves toward the object side and then moves toward the image side to reduce the distance between it and the fifth lens group L5. The seventh lens group L7, which is the final lens group, does not move during zooming. The fifth lens group L5 moves during focusing. The aperture diaphragm SP is located between the second and third lens groups and does not move during zooming.

[0022] In Example 1, an image-side vibration reduction group IS, which has a negative refractive power overall, is disposed closest to the image side in the third lens group L3. The image-side vibration reduction group IS is configured by bonding together two elements: a positive lens made of a resin layer Grep, and a negative lens serving as a base lens, which are disposed in that order from the object side to the image side.

[0023] The zoom lens 1b of Example 2 shown in FIG. 5 is a seven-group zoom lens that is composed of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, a sixth lens group L6 with negative refractive power, and a seventh lens group L7 with positive refractive power.

[0024] During zooming from the wide-angle end to the telephoto end, the first lens group L1 remains stationary, and the second lens group L2 moves toward the image side. The third lens group L3 moves toward the object side, and the fourth lens group L4 moves toward the object side to reduce the distance between it and the third lens group L3. The fifth lens group L5 moves toward the object side to reduce the distance between it and the fourth lens group L4 and then increase it. The sixth lens group L6 moves toward the object side and then moves toward the image side to increase the distance between it and the fifth lens group L5. The seventh lens group, which is the final lens group, remains stationary during zooming. The fifth lens group L5 moves during focusing. The aperture diaphragm SP is located between the second and third lens groups and remains stationary during zooming.

[0025] In Example 2, an image stabilization group IS, which has a negative refractive power overall, is disposed closest to the image side of the third lens group L3. The image stabilization group IS is configured by bonding together three elements: a positive lens made of a resin layer Grep, a positive lens as a base lens, and a negative lens, which are arranged in this order from the object side to the image side.

[0026] The zoom lens 1c of Example 3 shown in FIG. 9 is a seven-group zoom lens that is composed of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, a fifth lens group L5 with negative refractive power, a sixth lens group L6 with negative refractive power, and a seventh lens group L7 with positive refractive power.

[0027] In Example 3, the movement of each lens group during zooming from the wide-angle end to the telephoto end and during focusing is the same as in the zoom lens 1b of Example 2. Also in this example, the aperture stop SP is located between the second and third lens groups and does not move during zooming.

[0028] In Example 3, the vibration reduction group IS is arranged second from the image side in the third lens group L3. The vibration reduction group IS is configured by bonding together two elements: a negative lens made of a resin layer Grep arranged in order from the object side to the image side, and a negative lens serving as a base lens.

[0029] The single focal length lens 1d of Example 4 shown in Figure 13 is a four-group lens consisting of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with negative refractive power, and a fourth lens group L4 with positive refractive power. An aperture stop SP is disposed between the first lens group L1 and the second lens group L2. The second lens group L2 moves during focusing.

[0030] In Example 4, the entire third lens group L3 is used as the image stabilization group IS. The third lens group L3 is configured by bonding two elements, arranged from the object side to the image side, together: a positive lens made of a resin layer Grep, and a negative lens as a base lens.

[0031] The zoom lens 1e of Example 5 is a five-group zoom lens that is composed of, arranged in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with negative refractive power, and a fifth lens group L5 with negative refractive power.

[0032] During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side, and the second lens unit L2 remains stationary. The third lens unit L3 moves toward the object side, and the fourth lens unit L4 moves toward the object side so that the distance between it and the third lens unit L3 narrows and then widens. The fifth lens unit L5, which is the final lens unit, moves toward the object side so that the distance between it and the fourth lens unit L4 widens and then narrows slightly. The fourth lens unit L4 moves during focusing. The aperture diaphragm SP is located closest to the object in the second lens unit L2.

[0033] In Example 5, an image stabilization group IS, which has a negative refractive power overall, is arranged closest to the object in the second lens group L2. The image stabilization group IS is composed of three elements bonded together: a positive lens made of a resin layer Grep, a negative lens as a base lens, and a positive lens, which are arranged in that order from the object side to the image side.

[0034] As described above, in each embodiment, the vibration-reduction group IS includes an optical element (cemented lens) in which a resin layer Grep serving as a lens is cemented to a base lens. Resin materials generally have a lower specific gravity than glass, and using a resin layer in the vibration-reduction group is advantageous for reducing the size and weight of the entire vibration-reduction group. Furthermore, by forming an integrated optical element by closely adhering the resin material to the base lens, the configuration of the vibration-reduction group is simplified, making it possible to reduce the size of the entire lens system in the optical axis direction and reduce the weight of the vibration-reduction unit including the vibration-reduction group and the mechanism that drives it. In each embodiment, the refractive power of the resin layer Grep of the vibration-reduction group IS is set to a positive or negative value, with the opposite sign to the refractive power of the entire vibration-reduction group IS. This enables the resin layer Grep to suppress axial chromatic aberration within the vibration-reduction group IS and decentering chromatic aberration that occurs during shifting (movement).

[0035] The lenses 1a to 1e of each embodiment (numerical example) satisfy the condition of the following formula (1), where fr is the focal length of the resin layer Grep of the vibration isolation group IS and fis is the focal length of the vibration isolation group IS. -0.95≦fis / fr<0 (1) Equation (1) shows the condition for the relationship between the focal length fr of the resin layer lens Grep and the focal length fis of the entire image stabilization group IS, in order to effectively correct the decentering chromatic aberration and decentering coma aberration that occur when the image stabilization group IS shifts relative to the optical axis to correct image shake. The range of equation (1) is negative. This means that the focal length fr of the resin layer Grep must have the opposite sign to that of the image stabilization group IS. This allows for chromatic aberration correction by the image stabilization group IS and correction of decentering chromatic aberration and decentering coma aberration during shifting. If the focal length fis of the image stabilization group IS is small so that fis / fr exceeds the upper limit of equation (1), the refractive power of the image stabilization group IS will be too strong, making it difficult to adequately correct decentering coma aberration and decentering curvature of field aberration, which is undesirable. Furthermore, if the focal length fr of the resin layer Grep is so large that fis / fr exceeds 0, the upper limit of equation (1), it becomes difficult to correct chromatic aberration as an image stabilization group IS and to suppress decentering chromatic aberration and decentering coma aberration during shifting, which is undesirable.

[0036] On the other hand, if the focal length fis of the image stabilization group IS is large so that fis / fr falls below the lower limit of formula (1), it is necessary to increase the shift amount of the image stabilization group IS to correct image blur. This is undesirable because it increases the size of the image stabilization unit. Furthermore, if the shift amount of the image stabilization group IS becomes too large, it also increases high-order decentering coma aberrations, which is undesirable. Furthermore, if the focal length fr of the resin layer Grep is small so that fis / fr falls below the lower limit of formula (1), the refractive power of the resin layer Grep becomes too strong, which tends to result in excessive chromatic aberration and decentering chromatic aberration in the image stabilization group IS, which is undesirable. Furthermore, the volume of the resin layer increases in order to ensure the refractive power of the resin layer Grep, which is undesirable from the perspective of weight reduction.

[0037] It is more preferable to set the numerical range of the formula (1) as follows:

[0038] -0.50≦fis / fr≦-0.01 (1a) Furthermore, it is more preferable to set the numerical range of formula (1) as follows:

[0039] -0.30≦fis / fr≦-0.05 (1b) Furthermore, let vd_r be the Abbe number of the resin layer Grep with respect to the d-line, nd_r be the refractive index of the resin layer Grep with respect to the d-line, dr be the thickness of the resin layer Grep on the optical axis, and Dis be the thickness of the entire image stabilization group IS on the optical axis. βist be the lateral magnification of the image stabilization group IS when the focal length of the entire lens system (1a-1e) is at its maximum, and βrt be the combined lateral magnification of all lens groups on the image side of the image stabilization group IS in the same state. R1 be the radius of curvature of the lens surface in the image stabilization group IS closest to the object, and R2 be the radius of curvature of the lens surface closest to the image in the image stabilization group IS. Let Dmax be the maximum thickness of the resin layer Grep within the effective diameter in the optical axis direction, and Dmin be the minimum thickness. Let Dstpw be the distance on the optical axis from the aperture stop SP to the lens surface in the image stabilization group IS closest to the object when the focal length of the entire lens system is at its minimum, and OTDw be the distance on the optical axis from the lens surface closest to the object in the entire lens system to the image plane in the same state (total lens length). The focal length of the entire lens system at the telephoto end of the zoom lens (1a to 1c, 1e) is ft, the average Abbe number based on the d-line of at least one lens other than the resin layer in the image stabilization group IS is vd_gave, and the Abbe number based on the d-line of the resin layer Grep is vd_r. In this case, it is preferable that the lenses in each example satisfy at least one of the conditions of the following expressions (2) to (10). 15≦νd_r≦40 (2) 1.50≦nd_r≦1.75 (3) 0.001≦dr / Dis≦0.850 (4) 0.1≦|(1-βist)βrt|≦5.0 (5) |(R2+R1) / (R2-R1)|≦2.0 (6) 1.1≦Dmax / Dmin≦30.0 (7) |Dstpw / OTDw|≦0.8 (8) 0.05≦|fis / ft|≦2.00 (9) 5.0≦|νd_gave-νd_r|≦60.0 (10) Equation (2) shows the condition related to the Abbe number vd_r of the resin layer Grep for good chromatic aberration correction when the image stabilization group IS shifts. If vd_r exceeds the upper limit of equation (2), chromatic aberration correction in the image stabilization group IS tends to become excessive. In addition, vd_r approaches the Abbe number of the base lens material, and the refractive power of both the base lens material and the resin layer Grep tends to become strong, which undesirably results in an increase in the size of the image stabilization group IS.

[0040] On the other hand, if vd_r falls below the lower limit of formula (2), although this is advantageous for correcting first-order chromatic aberration in the image stabilization group IS, the partial dispersion ratio ΘgF for the g-line becomes large, making it difficult to correct second-order chromatic aberration. Also, it is difficult for a resin material to have an Abbe number below the lower limit of formula (2), which is undesirable.

[0041] Equation (3) shows the condition for the refractive index nd_r of the resin layer Grep to achieve both suppression of decentering coma aberration when the image stabilization group IS shifts and weight reduction of the image stabilization group IS. If nd_r exceeds the upper limit of equation (3), it is advantageous for reducing the weight of the image stabilization group IS. However, if the refractive index nd_r of the resin layer Grep is too high, if the surface precision of the resin layer deviates from the design value due to manufacturing errors or the like, the degradation of optical performance such as coma aberration will become too great, which is undesirable. Furthermore, it is difficult to obtain a refractive index that exceeds the upper limit of equation (3) for a resin material.

[0042] On the other hand, if nd_r falls below the lower limit of formula (3), the volume of the resin layer Grep increases, which is undesirable from the perspective of reducing size and weight. Furthermore, as the refractive index of the resin material decreases, the Abbe number νd_r tends to increase, which is undesirable from the perspective of correcting chromatic aberration in the vibration-reduction group IS because it limits the freedom of selection of glass for the base lens. Furthermore, it is difficult to obtain a refractive index below the lower limit of formula (3) for a resin material.

[0043] Equation (4) shows the condition related to the thickness dr of the resin layer Grep and the overall thickness Dis of the vibration isolation group IS in order to achieve both a reduction in the weight of the vibration isolation group IS and the suppression of various aberrations during shifting. If the thickness of the resin layer Grep is so large that dr / Dis exceeds the upper limit of equation (4), it becomes difficult to make the vibration isolation group IS small and lightweight, which is undesirable. Also, if the thickness of the vibration isolation group IS is so small that dr / Dis exceeds the upper limit of equation (4), the thickness of the resin layer Grep becomes relatively large, which is undesirable because it tends to reduce the moldability of the high-precision resin surface when manufacturing the resin layer Grep.

[0044] On the other hand, if the thickness of the resin layer Grep is small so that dr / Dis is below the lower limit of formula (4), this is advantageous from the perspective of reducing the size and weight of the image stabilization group IS. However, if the resin layer Grep is used as a positive lens, it becomes difficult to sufficiently increase the refractive power. As a result, chromatic aberration during shifting cannot be adequately corrected, which is undesirable. Furthermore, if the resin layer Grep is used as a negative lens, sufficient correction of decentration aberrations requires a large thickness deviation ratio, which is the ratio of the thickness on the optical axis to the thickness near the effective diameter, which is undesirable from the perspective of moldability. Furthermore, if the thickness of the resin layer Grep is large so that dr / Dis exceeds the upper limit of formula (4), the overall volume of the image stabilization group IS increases, which is undesirable from the perspective of reducing the size and weight. Furthermore, if the thickness of the image stabilization group IS is small so that dr / Dis exceeds the upper limit of formula (4), the thickness of the resin layer Grep becomes relatively large, which is undesirable because it easily reduces the moldability of the high-precision resin surface when manufacturing the resin layer Grep.

[0045] Equation (5) shows the condition regarding the relationship between the lateral magnification βist of the image stabilization group IS and the composite lateral magnification βrt of all lens groups on the image side of the image stabilization group IS, in order to ensure both the image shake compensation performance of the image stabilization group IS and size and weight reduction. Here, the lateral magnification βist and composite lateral magnification βrt are values at the telephoto end for a zoom lens. |(1-βist)βrt| in equation (5) shows the ratio of the amount of image shift on the image plane to the amount of shift of the image stabilization group IS, or what is known as decentration sensitivity.

[0046] If the lateral magnification of the image stabilization group IS is large enough that |(1-βist)βrt| exceeds the upper limit of equation (5), the amount of shift of the image stabilization group IS can be suppressed, which is advantageous for reducing the size of the image stabilization unit. However, if the sensitivity to decentering is too high and the image stabilization group IS shifts from the optical axis due to manufacturing errors or the like even when no image blur is occurring, this is undesirable because it will cause decentering coma aberrations and the like. Furthermore, mechanical control of the amount of shift of the image stabilization group IS will become difficult, which is also undesirable.

[0047] On the other hand, if the lateral magnification of the vibration reduction group IS is small so that |(1-βist)βrt| falls below the lower limit of equation (5), the shift amount of the vibration reduction group IS must be large in order to obtain a sufficient amount of correction (correction angle) for image blur, which results in an undesirable increase in the size of the vibration reduction unit.

[0048] Equation (6) indicates the condition related to the ratio of the radii of curvature R1 and R2 of the lens surfaces of image-side and object-side of image-side image-side image-shape compensation group IS for correcting decentering aberrations during shifting of image-shape compensation group IS. If |(R2+R1) / (R2-R1)| exceeds the upper limit of equation (6), the shape of the entire image-shape compensation group IS will become a meniscus shape, which is undesirable because it will be difficult to suppress decentering coma during shifting.

[0049] Equation (7) expresses the condition for the ratio of the maximum thickness Dmax to the minimum thickness Dmin of the resin layer Grep in the optical axis direction, the so-called thickness deviation ratio, which is necessary to achieve both a reduction in the weight of the image stabilization group IS and the suppression of various aberrations during shifting. Both the maximum thickness Dmax and the minimum thickness Dmin are determined within the range of the resin layer Grep within the effective diameter of the lens. If Dmax / Dmin exceeds the upper limit of equation (7), although this is advantageous for correcting decentration aberrations in the image stabilization group IS, it reduces moldability, which is undesirable from a manufacturing perspective. Furthermore, a large thickness deviation ratio tends to increase the volume of the resin layer Grep, which is undesirable from a weight reduction perspective. On the other hand, if Dmax / Dmin falls below the lower limit of equation (7), it becomes difficult to sufficiently correct decentration aberrations during shifting of the image stabilization group IS, which is undesirable.

[0050] Equation (8) shows the condition related to the relationship between the distance Dstpw from the aperture stop SP to the lens surface of the image stabilization group IS closest to the object and the overall lens length OTDw, in order to suppress the occurrence of various aberrations when the image stabilization group IS shifts. The distance Dstpw and the overall lens length OTDw here are values at the wide-angle end of a zoom lens. If |Dstpw / OTDw| exceeds the upper limit of equation (8), the distance Dstpw from the aperture stop SP to the image stabilization group IS becomes too large, making it difficult to suppress curvature of field when the image stabilization group IS shifts, which is undesirable.

[0051] Equation (9) expresses a condition regarding the relationship between the focal length ft of the entire lens system and the focal length fis of the image stabilization group IS in order to simultaneously suppress aberrations during shifting of the image stabilization group IS and reduce the size and weight of the image stabilization group IS. Here, the focal length ft of the entire system is the focal length at the telephoto end in a zoom lens. If the focal length of the image stabilization group IS is large enough that |fis / ft| exceeds the upper limit of equation (9), it will be necessary to increase the amount of shift of the image stabilization group IS, which is undesirable from the perspective of reducing size and weight. Furthermore, if the focal length of the entire system is small enough that |fis / ft| exceeds the upper limit of equation (9), the zoom ratio of the zoom lens will become small, which is also undesirable.

[0052] On the other hand, if the focal length of the image stabilization group IS is short so that |fis / ft| falls below the lower limit of equation (9), the amount of shift of the image stabilization group IS can be suppressed. However, this is not preferable because the refractive power of the image stabilization group IS is too strong, making it difficult to correct various aberrations when the image stabilization group IS is not shifted and various aberrations such as decentering coma when it is shifted. Furthermore, if the focal length of the entire system is long so that |fis / ft| falls below the lower limit of equation (9), it becomes difficult to suppress axial chromatic aberration and the like at the telephoto end, which is also not preferable.

[0053] Equation (10) indicates the condition for the difference between the average Abbe number vd_gave of the lenses other than the resin layer in the image stabilization group IS and the Abbe number vd_r of the resin layer Grep, in order to satisfactorily correct the axial chromatic aberration that occurs in the image stabilization group IS and the decentering chromatic aberration that occurs when the image stabilization group IS is shifted. If this difference exceeds the upper limit of equation (10), the chromatic aberration that occurs in the image stabilization group IS can be suppressed. However, this is undesirable because it reduces the difference in refractive power between the resin layer Grep and the base lens, making it difficult to suppress spherical aberration and coma aberration when the image stabilization group IS is not shifted.

[0054] On the other hand, if the difference falls below the lower limit of formula (10), the difference in refractive power between the resin layer Grep and the base lens must be increased in order to effectively suppress chromatic aberration, which makes it difficult to suppress decentering coma aberration when the image stabilization group IS shifts, which is undesirable.Furthermore, if the difference falls below the lower limit of formula (10), it becomes difficult to correct chromatic aberration in the image stabilization group IS, which is also undesirable.

[0055] It is more preferable to set the numerical ranges of the above formulas (2) to (10) as follows. Some corrections have been made in relation to the numerical values in Table 1.

[0056] 20≦νd_r≦40 (2a) 1.50≦nd_r≦1.70 (3a) 0.005≦dr / Dis≦0.600 (4a) 0.2≦|(1-βist)βrt|≦4.0 (5a) |(R2+R1) / (R2-R1)|≦1.7 (6a) 1.5≦Dmax / Dmin≦20.0 (7a) |Dstpw / OTDw|≦0.7 (8a) 0.1≦|fis / ft|≦1.8 (9a) 8.0≦|νd_gave-νd_r|≦55.0 (10a) Furthermore, it is more preferable to set the numerical ranges of the formulas (2) to (10) as follows:

[0057] 25≦νd_r≦38 (2b) 1.55≦nd_r≦1.65 (3b) 0.007≦dr / Dis≦0.400 (4b) 0.3≦|(1-βist)βrt|≦3.0 (5b) |(R2+R1) / (R2-R1)|≦1.5 (6b) 2.0≦Dmax / Dmin≦15.0 (7b) |Dstpw / OTDw|≦0.65 (8b) 0.15≦|fis / ft|≦1.50 (9b) 10.0≦|νd_gave-νd_r|≦52.0 (10b) In each embodiment, it is preferable that the resin layer Grep of the vibration reduction group IS has an optical surface that comes into contact with air (air-contact surface) on either the object side or the image side. If both the object side and the image side of the resin layer Grep are cemented to glass, it is not preferable because the chromatic aberration correction of the resin layer Grep cannot be performed sufficiently. Furthermore, it is preferable that the air-contact surface of the resin layer Grep is aspherical. By making it an aspherical surface, it becomes possible to more effectively correct decentering coma aberration when the vibration reduction group IS shifts.

[0058] In each embodiment, from the viewpoint of size and weight reduction, it is preferable that the vibration isolation group IS be a single cemented lens in which the resin layer Grep and at least one lens other than the resin layer are all cemented together.

[0059] In addition, in an embodiment of the zoom lens, the zoom lens is composed of, in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, and a rear group (L3~) located closer to the image than the second lens group, and it is preferable that the vibration reduction group IS is included in the second lens group L2 or the rear group. With this configuration, it is possible to reduce the overall length of the zoom lens while also reducing the diameter of the vibration reduction group IS. Note that it is sufficient for the rear group to include at least one lens group.

[0060] Furthermore, in each embodiment, the resin layer Grep is preferably formed from an ultraviolet curable resin. By using an ultraviolet curable resin, the resin layer Grep can be made thinner, which is preferable from the viewpoint of reducing size and weight.

[0061] According to each embodiment, it is possible to realize high optical performance, such as suppressing the occurrence of chromatic aberration when the image stabilization group IS is shifted, while reducing the size and weight of the image stabilization group IS.

[0062] Numerical Examples 1 to 5 corresponding to Examples 1 to 5 are shown below. In each numerical example, surface number i indicates the order of the optical surface when counted from the object side. r (mm) is the radius of curvature of the i-th optical surface, and d (mm) is the lens thickness or distance (air gap) on the optical axis between the i-th surface and the (i+1)-th surface. nd is the refractive index with respect to the d-line of the optical material between the i-th surface and the (i+1)-th surface. νdi is the Abbe number with the d-line of the optical material between the i-th surface and the (i+1)-th surface as the reference. When 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 are Nd, NF, and NC, respectively, the Abbe number νd is νd=(Nd-1) / (NF-NC) It is expressed as:

[0063] In each numerical example, d, focal length, F-number, and half angle of view (°) are values when focused on an object at infinity. "BF" (back focus) is the distance on the optical axis from the final lens surface, which is the lens surface closest to the image, to the paraxial image plane, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the frontmost lens surface, which is the lens surface closest to the object, to the final lens surface, plus the back focus.

[0064] An "*" next to a surface number means that the surface is aspherical. The shape of an aspherical surface 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, and A10 are aspherical coefficients. "ex" is x 10 -xmeans.

[0065]

number

[0066] The relationship between the conditions of formulas (1) to (10) and each example (numerical example) is summarized in Table 1. Lenses 1a to 1e of examples 1 to 5 all satisfy the conditions of formulas (1) to (10) (and also formulas (1a) to (10a) and formulas (1b) to (10b)). (Numerical example 1) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 287.836 2.20 1.84666 23.8 75.07 2 117.040 8.77 1.49700 81.5 72.42 3 -463.649 0.15 71.69 4 76.445 7.27 1.72916 54.7 67.41 5 288.757 (variable) 66.52 6 130.630 1.40 1.88300 40.8 36.21 7 24.178 6.11 29.46 8 -231.647 1.00 1.53775 74.7 28.71 9 43.461 0.10 26.53 10 37.552 3.58 1.85478 24.8 26.29 11 74.422 4.10 24.78 12 -29.397 1.10 1.49700 81.5 24.36 13 560.309 2.50 1.85478 24.8 25.80 14 -82.474 (variable) 26.38 15 (Aperture) ∞ (Variable) 27.44 16 44.442 4.32 1.89286 20.4 29.70 17 -8802.889 0.12 29.58 18 40.767 1.50 2.00100 29.1 29.23 19 23.094 11.28 1.49700 81.5 27.72 20 -29.992 0.29 27.34 21 -29.172 1.40 2.00069 25.5 27.15 22 474.342 2.01 28.12 23 84.351 5.21 1.49700 81.5 29.71 24 -52.194 0.82 30.06 25* -104.554 0.50 1.59022 30.1 30.09 26 -77.348 1.30 1.48749 70.2 30.09 27 111.339 (variable) 30.41 28 46.242 9.43 1.49700 81.5 36.90 29 -58.476 0.15 37.04 30* 63.823 0.16 1.59022 30.1 35.76 31 82.814 1.35 1.95906 17.5 35.69 32 46.540 5.00 2.00100 29.1 34.91 33 609.389 (variable) 34.38 34 186.529 3.09 1.95906 17.5 32.70 35 -171.732 0.15 32.13 36 -324.395 1.10 1.77047 29.7 31.62 37 33.303 (variable) 29.36 38* -29.257 0.45 1.59022 30.1 28.94 39 -25.615 1.60 1.72916 54.7 28.97 40 -94.099 (variable) 31.26 41 47.581 6.51 1.48749 70.2 40.90 42 ∞ (variable) 41.08 Image plane ∞ Aspheric data Page 25 K = 0.00000e+000 A 4= 1.28501e-006 A 6=-9.97125e-010 A 8= 7.44439e-012 A10=-2.13750e-014 A12= 1.80140e-017 Page 30 K = 0.00000e+000 A 4=-6.17655e-006 A 6=-9.03755e-010 A 8=-1.77689e-011 A10=4.08615e-014 A12=-4.01447e-017 Page 38 K = 0.00000e+000 A 4=-6.43322e-006 A 6= 1.45019e-008 A 8=-1.53727e-010 A10=6.74684e-013 A12=-1.13415e-015 Various data Zoom ratio 4.71 Wide-angle Mid-range Telephoto Focal length 24.72 61.33 116.36 F-number 2.91 2.91 2.91 Half angle of view (°) 37.12 19.43 10.53 Image height 21.64 21.64 21.64 Lens length 178.45 191.24 204.02 BF 14.59 14.59 14.59 d 5 0.90 29.26 50.55 d14 24.92 9.35 0.84 d15 17.38 5.86 1.50 d27 8.70 5.14 2.79 d33 1.50 5.17 4.79 d37 13.65 15.48 26.81 d40 0.80 10.38 6.14 d42 14.59 14.59 14.59 Entrance pupil position 36.26 88.83 157.67 Exit pupil position -107.74 -89.47 -70.91 Front principal point position 55.98 114.02 115.66 Back principal point position -10.14 -46.74 -101.77 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 122.94 18.39 5.51 -5.87 2 6 -24.45 19.89 3.09 -12.16 3 16 70.96 28.74 -10.25 -26.71 4 28 32.41 16.09 4.32 -5.68 5 34 -69.15 4.34 3.43 1.03 6 38 -56.65 2.05 -0.44 -1.67 7 41 97.60 6.51 0.00 -4.37 Single lens data Lens starting surface focal length 1 1 -234.35 2 2 188.98 3 4 140.56 4 6 -33.81 5 8 -67.97 6 10 84.87 7 12 -56.17 8 13 84.26 9 16 49.54 10 18 -55.58 11 19 28.24 12 21 -27.42 13 23 65.71 14 25 500.22 15 26 -93.41 16 28 53.56 17 30 470.09 18 31 -112.84 19 32 50.11 20 34 93.62 21 36 -39.15 22 38 333.28 23 39 -48.75 24 41 97.60 (Numerical example 2) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 2087.789 2.20 2.00100 29.1 74.30 2 118.129 8.40 1.49700 81.5 70.56 3 -432.633 0.15 69.80 4 155.344 5.06 1.49700 81.5 65.50 5 -1452.229 0.00 64.65 6 78.029 5.78 1.81600 46.6 58.71 7 357.852 (variable) 58.00 8 336.817 1.40 1.88300 40.8 44.02 9 29.285 7.33 35.80 10 -181.413 1.00 1.59522 67.7 35.46 11 67.132 0.11 33.57 12 43.305 3.00 1.85478 24.8 33.02 13 69.829 5.87 32.04 14 -37.040 1.10 1.49700 81.5 31.71 15 176.336 0.35 31.10 16 336.419 3.27 1.85478 24.8 31.10 17 -75.335 (variable) 30.99 18 (Aperture) ∞ (Variable) 30.47 19 51.100 4.23 1.77830 23.9 33.04 20 646.565 12.18 32.94 21 31.714 1.50 2.00069 25.5 31.80 22 22.464 12.02 1.49700 81.5 30.03 23 -39.484 1.40 1.92286 18.9 29.28 24 -574.242 1.87 29.40 25* -183.377 0.20 1.56650 37.6 29.41 26 -156.034 4.62 1.92286 18.9 29.42 27 -32.348 1.30 1.84666 23.8 29.57 28 162.389 (variable) 30.61 29* 113.215 0.05 1.59022 30.1 36.97 30 131.870 5.06 1.49700 81.5 37.13 31 -120.504 0.14 38.00 32 65.847 8.24 1.77250 49.6 40.03 33 -71.507 (variable) 39.92 34 538.020 4.63 1.92286 18.9 35.17 35 -59.131 1.10 1.73800 32.3 34.60 36 42.302 (variable) 31.63 37* -36.742 0.45 1.59022 30.1 30.74 38 -30.526 1.60 1.72916 54.7 30.75 39 -148.485 (variable) 32.56 40 107.754 5.26 1.49700 81.5 39.78 41 -117.305 (variable) 40.19 Image plane ∞ Aspheric data Page 25 K = 0.00000e+000 A 4= 3.17809e-007 A 6= 6.04584e-010 A 8=-1.25210e-012 A10=-1.01467e-014 A12= 2.97341e-017 Page 29 K = 0.00000e+000 A 4=-5.60367e-006 A 6= 1.76853e-009 A 8=-7.01013e-012 A10= 1.89743e-014 A12=-1.92142e-017 Page 37 K = 0.00000e+000 A 4=-5.62020e-006 A 6=-1.34754e-009 A 8=-2.04562e-011 A10=3.24662e-014 A12=-6.83028e-017 Various data Zoom ratio 4.71 Wide-angle Mid-range Telephoto Focal length 24.73 39.98 116.36 F-number 2.91 2.91 2.91 Half angle of view (°) 37.39 28.42 10.53 Image height 21.64 21.64 21.64 Lens total length 213.46 213.46 213.46 BF 13.81 13.81 13.81 d 7 0.90 10.57 41.17 d17 40.70 31.03 0.43 d18 19.51 10.63 3.00 d28 10.18 6.80 2.30 d33 3.34 1.50 4.26 d36 13.36 17.76 27.79 d39 0.80 10.50 9.84 d41 13.81 13.81 13.81 Entrance pupil position 42.40 58.24 130.41 Exit pupil position -148.93 -125.59 -94.68 Front principal point position 63.37 86.76 121.98 Back principal point position -10.91 -26.16 -102.54 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 106.16 21.59 11.21 -1.93 2 8 -28.55 23.42 2.16 -17.17 3 19 81.72 39.31 -24.35 -40.92 4 29 33.65 13.49 4.76 -3.70 5 34 -80.05 5.73 3.64 0.58 6 37 -64.06 2.05 -0.30 -1.51 7 40 113.89 5.26 1.70 -1.85 Single lens data Lens starting surface focal length 1 1 -125.16 2 2 187.66 3 4 282.66 4 6 121.16 5 8 -36.40 6 10 -82.20 7 12 126.77 8 14 -61.49 9 16 72.27 10 19 71.07 11 21 -83.76 12 22 30.79 13 23 -46.00 14 25 1842.37 15 26 43.44 16 27 -31.76 17 29 1354.57 18 30 127.54 19 32 45.57 20 34 57.94 21 35 -33.26 22 37 297.68 23 38 -53.00 24 40 113.89 (Numerical example 3) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 304.000 2.20 1.84666 23.8 71.53 2 92.955 9.24 1.49700 81.5 65.89 3 -371.952 0.15 64.74 4 76.828 5.61 1.83481 42.7 56.54 5 364.502 (variable) 55.27 6 421.524 1.40 1.88300 40.8 46.29 7 30.091 7.99 37.33 8 -159.885 1.00 1.49700 81.5 36.91 9 51.475 0.08 34.34 10 43.008 3.06 2.05090 26.9 34.07 11 67.114 6.21 33.04 12 -38.079 1.10 1.49700 81.5 32.68 13 327.741 4.59 1.85478 24.8 32.00 14 -81.468 (variable) 31.67 15 (Aperture) ∞ (Variable) 32.41 16 54.786 3.49 1.92286 18.9 34.29 17 177.454 8.45 34.14 18 30.263 1.50 2.00069 25.5 33.97 19 22.637 10.55 1.49700 81.5 32.06 20 -147.905 0.13 31.31 21 -282.889 1.40 1.80810 22.8 31.07 22 58.671 1.50 30.32 23* 56.597 0.05 1.59022 30.1 30.43 24 52.518 5.69 1.49700 81.5 30.39 25 -75.427 2.44 30.41 26 -47.713 1.30 1.80810 22.8 30.40 27 159.626 (variable) 31.74 28* 84.668 0.07 1.59022 30.1 38.87 29 106.190 5.61 1.49700 81.5 39.01 30 -99.010 0.15 39.77 31 84.097 7.77 1.90043 37.4 41.84 32 -75.592 (variable) 41.78 33 293.202 3.43 1.98612 16.5 36.51 34 -121.711 0.15 35.94 35 -172.611 1.10 1.90043 37.4 35.22 36 43.474 (variable) 32.84 37* -30.478 0.45 1.59022 30.1 32.11 38 -27.469 1.60 1.72916 54.7 32.14 39 -70.075 (variable) 34.71 40 65.669 5.25 1.72916 54.7 43.05 41 ∞ (variable) 43.06 Image plane ∞ Aspheric data Page 23 K = 0.00000e+000 A 4=-1.56777e-006 A 6=-2.16556e-009 A 8= 6.57664e-012 A10=-1.33254e-014 A12= 1.71769e-017 Page 28 K = 0.00000e+000 A 4=-5.98706e-006 A 6= 4.16976e-009 A 8=-1.36129e-011 A10=2.95803e-014 A12=-2.54789e-017 Page 37 K = 0.00000e+000 A 4=-2.64638e-006 A 6= 2.34537e-009 A 8=-3.38245e-011 A10=9.90165e-014 A12=-1.71434e-016 Various data Zoom ratio 4.71 Wide-angle Mid-range Telephoto Focal length 24.72 39.97 116.37 F-number 2.91 2.91 2.91 Half angle of view (°) 37.12 28.42 10.53 Image height 21.64 21.64 21.64 Lens total length 208.46 208.46 208.46 BF 13.50 13.50 13.50 d 5 0.90 9.49 38.99 d14 38.94 30.35 0.85 d15 22.77 12.22 1.50 d27 8.95 6.28 2.34 d32 3.41 1.62 4.50 d36 14.49 18.45 28.45 d39 0.80 11.86 13.62 d41 13.50 13.50 13.50 Entrance pupil position 41.45 55.51 122.04 Exit pupil position -253.62 -186.07 -135.48 Front principal point position 63.88 87.48 147.51 Back principal point position -11.22 -26.47 -102.87 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 110.47 17.20 7.03 -3.52 2 6 -30.54 25.43 1.82 -18.95 3 16 90.23 36.48 -35.10 -44.29 4 28 31.24 13.60 4.81 -3.51 5 33 -70.22 4.68 3.27 0.78 6 37 -72.71 2.05 -0.81 -2.04 7 40 90.06 5.25 0.00 -3.04 Single lens data Lens starting surface focal length 1 1 -158.91 2 2 150.63 3 4 115.58 4 6 -36.76 5 8 -78.22 6 10 106.98 7 12 -68.57 8 13 76.73 9 16 84.72 10 18 -99.56 11 19 40.33 12 21 -60.02 13 23 -1240.33 14 24 63.23 15 26 -45.33 16 28 706.86 17 29 104.04 18 31 45.25 19 33 87.58 20 35 -38.47 21 37 446.65 22 38 -62.96 23 40 90.06 (Numerical example 4) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 70.752 6.52 1.90043 37.4 56.88 2 440.500 0.15 56.29 3 57.565 9.57 1.49700 81.5 52.51 4 -332.389 2.00 1.88300 40.8 50.73 5 84.915 0.15 47.13 6 50.200 6.94 1.49700 81.5 45.81 7 334.045 0.15 44.29 8 135.929 2.00 1.67270 32.1 43.09 9 32.936 2.62 38.36 10 49.461 4.03 1.72916 54.7 38.26 11 142.439 (variable) 37.51 12 (Aperture) ∞ 2.30 36.57 13 -555.457 1.68 1.92286 18.9 35.07 14 -154.056 1.30 1.59522 67.7 34.74 15 38.151 (variable) 32.08 16* 414.834 0.50 1.59022 30.1 29.58 17 -615.628 1.00 1.82522 41.7 29.57 18 78.957 (variable) 29.25 19 41.210 11.92 1.59522 67.7 32.94 20 -28.912 1.30 1.66565 35.6 33.86 21 298.910 0.19 36.43 22 197.707 1.80 1.80810 22.8 36.77 23 32.848 11.15 1.88300 40.8 38.82 24 -92.968 1.75 39.36 25 -59.032 1.80 1.57197 38.1 39.36 26 35.777 11.74 1.99202 27.0 42.46 27 -100.164 8.69 42.17 28* -50.963 2.00 1.76802 49.2 37.57 29 -3568.112 (variable) 38.81 Image plane ∞ Aspheric data Page 16 K = 0.00000e+000 A 4= 1.59786e-007 A 6= 1.73424e-009 A 8=-1.56292e-012 Page 28 K = 0.00000e+000 A 4=-1.01224e-005 A 6= 2.28729e-008 A 8=-1.22091e-010 A10=2.83964e-013 A12=-2.41602e-016 Focal length 82.47 F-number 1.45 Half angle of view (°) 14.70 Image height 21.64 Lens length 126.52 BF 13.50 d11 2.50 d15 16.06 d18 1.20 d29 13.50 Entrance pupil position 40.78 Exit pupil position -67.48 Front principal point position 39.26 Back principal point position -68.97 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 79.48 34.14 -7.82 -27.66 2 12 -66.01 5.28 3.91 -0.07 3 16 -106.39 1.50 0.97 0.11 4 19 39.11 52.34 1.11 -28.22 Single lens data Lens starting surface focal length 1 1 92.84 2 3 99.54 3 4 -76.43 4 6 117.91 5 8 -65.13 6 10 102.05 7 13 230.54 8 14 -51.24 9 16 419.97 10 17 -84.75 11 19 30.48 12 20 -39.54 13 22 -48.99 14 23 28.68 15 25 -38.68 16 26 27.77 17 28 -67.34 (Numerical example 5) Unit: mm Surface Data Surface number rd nd νd Effective diameter 1 88.418 1.50 1.88300 40.8 58.70 2 63.666 8.74 1.49700 81.5 57.43 3 -833.690 (variable) 57.10 4* -106.403 1.00 1.59022 30.1 32.47 5 -64.250 1.10 1.72916 54.7 32.47 6 29.236 4.74 1.76200 40.1 32.73 7 79.904 1.26 32.74 8 94.393 4.99 1.76182 26.5 33.09 9 -71.324 0.15 33.14 10 90.907 5.93 1.49700 81.5 32.03 11 -45.508 1.25 2.05090 26.9 31.47 12 896.670 1.06 31.34 13 (Aperture) ∞ (Variable) 31.31 14 126.596 1.30 2.05090 26.9 34.71 15 52.713 7.76 1.58313 59.4 34.97 16 -72.568 0.15 35.80 17 67.589 3.92 1.72916 54.7 36.93 18 -1930.147 (variable) 36.79 19 509.219 1.15 1.53775 74.7 29.60 20 28.124 (variable) 28.85 21 -57.869 6.04 1.59270 35.3 31.10 22 -22.224 1.60 1.49700 81.5 31.77 23 -4514.292 (variable) 34.70 Image plane ∞ Aspheric data Side 4 K = 0.00000e+000 A 4= 6.85519e-007 A 6= 4.19594e-009 A 8=-4.15125e-011 A10=2.06560e-013 A12=-3.86264e-016 Various data Zoom ratio 3.76 Wide-angle Mid-range Telephoto Focal length 103.16 216.79 387.89 F-number 4.64 6.50 7.30 Half angle of view (°) 11.84 5.70 3.19 Image height 21.64 21.64 21.64 Lens length 176.10 235.23 288.59 BF 15.98 50.92 63.01 d 3 2.11 61.24 114.60 d13 61.57 37.67 27.84 d18 29.18 15.57 1.86 d20 13.60 16.18 27.63 d23 15.98 50.92 63.01 Entrance pupil position 24.02 127.92 345.02 Exit pupil position -64.37 -51.72 -52.41 Front principal point position -5.27 -113.18 -570.71 Back principal point position -87.18 -165.87 -324.88 Lens group data Group starting plane Focal length Lens length Front principal point position Rear principal point position 1 1 219.80 10.24 -0.19 -6.85 2 4 -225.92 21.49 4.50 -8.67 3 14 53.78 13.13 5.57 -2.43 4 19 -55.40 1.15 0.79 0.04 5 21 -176.88 7.64 -2.98 -7.96 Single lens data Lens starting surface focal length 1 1 -265.09 2 2 119.40 3 4 272.37 4 5 -27.42 5 6 58.15 6 8 54.03 7 10 61.91 8 11 -41.18 9 14 -86.73 10 15 53.58 11 17 89.63 12 19 -55.40 13 21 57.26 14 22 -44.94

[0067] [Table 1]

[0068] Figure 21 shows a digital still camera 10 as an imaging device that uses the lens (1a to 1e) of each embodiment as an imaging optical system. In Figure 21, 113 denotes a camera body, and 111 denotes an imaging optical system. 112 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor that is built into the camera body 113 and receives and captures (photoelectrically converts) an optical image formed by the imaging optical system 111. The camera body 113 may be a single-lens reflex camera with a quick-turn mirror, or may be a mirrorless camera without a quick-turn mirror.

[0069] According to each embodiment, it is possible to provide an imaging device that can obtain high optical performance even when the vibration reduction group is shifted, while the lens barrel that houses the imaging optical system is small and lightweight.

[0070] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of symbols]

[0071] 1a~1e lenses L1~L7 lens group SP aperture stop IS vibration isolation group Grep resin layer IP image plane

Claims

1. a movable group that is movable in a direction eccentric to the optical axis, the movable group is made up of a resin layer and one lens bonded together, When the focal length of the resin layer is fr and the focal length of the movable group is fis, -0.95≦fis / fr<0 An optical system characterized by satisfying the following conditions:

2. When the Abbe number of the resin layer based on the d line is νd_r, 15≦νd_r≦40 2. The optical system according to claim 1, wherein the following condition is satisfied:

3. When the refractive index of the resin layer with respect to the d line is nd_r, 1.50≦nd_r≦1.75 3. The optical system according to claim 1, wherein the following condition is satisfied:

4. When the thickness of the resin layer on the optical axis is dr and the thickness of the entire movable group on the optical axis is Dis, 0.001≦dr / Dis≦0.850 4. The optical system according to claim 1, wherein the following condition is satisfied:

5. When the focal length of the optical system is at its maximum, the lateral magnification of the movable group is βist, and the combined lateral magnification of all the lenses arranged closer to the image than the movable group is βrt, 0.1≦|(1−βist)βrt|≦5.0 5. The optical system according to claim 1, wherein the following condition is satisfied:

6. When the radius of curvature of the lens surface closest to the object side in the movable group is R1 and the radius of curvature of the lens surface closest to the image side in the movable group is R2, |(R2+R1) / (R2-R1)|≦2.0 6. The optical system according to claim 1, wherein the following condition is satisfied:

7. When the maximum thickness of the resin layer in the optical axis direction is Dmax and the minimum thickness is Dmin, 1.1≦Dmax / Dmin≦30.0 7. The optical system according to claim 1, wherein the following condition is satisfied:

8. the optical system has an aperture stop arranged on the object side of the movable group, When the focal length of the optical system is at its shortest, the distance on the optical axis from the aperture stop to the movable group is Dstpw, and the distance on the optical axis from the lens surface closest to the object in the optical system to an image plane is OTDw, |Dstpw / OTDw|≦0.8 8. The optical system according to claim 1, wherein the following condition is satisfied:

9. When the maximum focal length of the optical system is ft, 0.05≦|fis / ft|≦2.00 9. The optical system according to claim 1, wherein the following condition is satisfied:

10. When the Abbe number of the resin layer based on the d line is νd_r and the average Abbe number of the lenses other than the resin layer included in the movable group is νd_gave, 5.0≦|νd_gave−νd_r|≦60.0 10. The optical system according to claim 1, wherein the following condition is satisfied:

11. The optical system according to claim 1 , wherein the resin layer has an optical surface that is in contact with air.

12. 12. The optical system according to claim 11, wherein the optical surface is an aspheric surface.

13. 13. The optical system according to claim 1, wherein the movable group is composed of the resin layer and at least one lens, which are bonded together.

14. 14. The optical system according to claim 1, wherein the resin layer is made of an ultraviolet curable resin.

15. The lens has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group including at least one lens group, which are arranged in this order from the object side to the image side, and the spacing between adjacent lens groups changes during zooming, 15. The optical system according to claim 1, wherein the movable group is included in the second lens group or the rear lens group.

16. The optical system comprises, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, a sixth lens group having negative refractive power, and a seventh lens group having positive refractive power; 16. The optical system of claim 15, wherein the movable group is included in the third lens group.

17. the lens comprises, arranged in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power, and a fifth lens group having negative refractive power; 16. The optical system of claim 15, wherein the movable group is included in the second lens group.

18. The zoom lens comprises a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and a fourth lens group having a positive refractive power, which are arranged in this order from the object side to the image side, and the spacing between adjacent lens groups changes during zooming.

15. The optical system according to claim 1, wherein the movable group is included in the third lens group.

19. 19. The optical system according to claim 1, wherein the movable group moves during image blur correction.

20. An optical system according to any one of claims 1 to 19; and an imaging element that images an object via the optical system.

Images