JP7379081B2 - Optical system and imaging device having the same - Google Patents

Description

The present invention relates to an optical system and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and the like.

As an imaging optical system used in an imaging device, there is a demand for an optical system that has a short overall lens length and has high optical performance when correcting image blur. When the optical system is tilted due to camera shake or the like, the photographed image is blurred by an amount corresponding to the tilt angle of the lens, the focal length, and the object distance.

Patent Document 1 discloses that in order to reduce the occurrence of decentering aberration during image stabilization, some lens groups of the optical system are rotated at a small angle around a point on the optical axis that is variable depending on the object distance. An optical system is disclosed that is rotated at . In the optical system disclosed in Patent Document 1, in a three-group zoom lens consisting of a first lens group to a third lens group having negative, positive, and positive refractive powers in order from the object side to the image side, the second lens group Image stabilization is performed by shifting and tilting the camera.

JP 2018-4885 Publication

Generally, there is a component in the direction perpendicular to the optical axis in the anti-vibration lens group, that is, a shift component, and a component in the rotational direction in the plane consisting of the optical axis direction and the direction perpendicular to the optical axis in the anti-vibration lens group. That is, it is important to appropriately set each tilt component. If the shift component and tilt component of the image stabilization lens group are not appropriately set during image blur correction, it is difficult to maintain high optical performance when the image blur correction angle is expanded.

In the optical system disclosed in Patent Document 1, since vibration isolation is performed based on the rotation center, it is not possible to set an appropriate tilt component for an arbitrary shift component, and eccentricity is caused over the entire shift during vibration isolation. It is difficult to reduce aberrations.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical system and an imaging device that can achieve high optical performance while enlarging the image blur correction angle when correcting image blur.

An optical system as one aspect of the present invention is an optical system having an anti-vibration lens group and an aperture diaphragm, the anti-vibration lens group consisting of one single lens or one cemented lens, and a shift component and an aperture stop. Image stabilization is performed by moving the image so as to include a tilt component, and the inclination angle of the paraxial ray that enters the anti-shake lens group is α1, and the inclination angle of the paraxial ray that exits from the anti-shake lens group is α2. , the shift component of the anti-vibration lens group is Y, the tilt component of the anti-vibration lens group is θ, the focal length of the anti-vibration lens group is fis , from the aperture stop to the nearest aperture stop in the anti-vibration lens group. Let Lsp be the distance on the optical axis to the surface apex on the aperture stop side of the lens disposed in , and L be the distance from the lens surface closest to the object side of the optical system to the lens surface closest to the image side of the optical system. When , a predetermined conditional expression is satisfied.

An imaging device according to another aspect of the present invention includes an optical system and an imaging element that photoelectrically converts an optical image formed through the optical system.

Other objects and features of the invention are illustrated in the following examples.

According to the present invention, it is possible to provide an optical system and an imaging device that can achieve high optical performance while enlarging the image blur correction angle when correcting image blur.

3 is a cross-sectional view of the optical system in Example 1. FIG. 3 is a longitudinal aberration diagram of the optical system in Example 1. FIG. FIG. 3 is a lateral aberration diagram of the optical system in Example 1. FIG. FIG. 3 is a lateral aberration diagram during image blur correction of the optical system in Example 1. FIG. 3 is a cross-sectional view of an optical system in Example 2. FIG. FIG. 7 is a longitudinal aberration diagram of the optical system in Example 2. 3 is a lateral aberration diagram of the optical system in Example 2. FIG. FIG. 7 is a diagram of lateral aberration during image blur correction of the optical system in Example 2. FIG. 3 is a cross-sectional view of an optical system in Example 3. FIG. FIG. 7 is a longitudinal aberration diagram of the optical system in Example 3. FIG. 7 is a lateral aberration diagram of the optical system in Example 3. FIG. 7 is a diagram of lateral aberration when correcting image blur in the optical system in Example 3. FIG. 7 is a cross-sectional view of an optical system at a wide-angle end, an intermediate position, and a telephoto end in Example 4. FIG. 7 is a longitudinal aberration diagram of the optical system in Example 4 at the wide-angle end, middle, and telephoto end. FIG. 7 is a lateral aberration diagram of the optical system in Example 4 at the wide-angle end, middle, and telephoto end. FIG. 7 is a diagram of lateral aberrations at the wide-angle end, intermediate, and telephoto end during image blur correction of the optical system in Example 4. FIG. 7 is a cross-sectional view of an optical system in Example 5. FIG. 7 is a longitudinal aberration diagram of the optical system in Example 5. FIG. 7 is a lateral aberration diagram of the optical system in Example 5. FIG. 7 is a diagram of lateral aberration when correcting image blur in the optical system in Example 5. FIG. FIG. 7 is an explanatory diagram of the inclination angle of a paraxial axial ray that enters the anti-vibration lens group and the inclination angle of the paraxial axial ray that exits from the anti-vibration lens group in each example. FIG. 3 is an explanatory diagram of a vibration isolation mechanism in each example. FIG. 3 is an explanatory diagram of tilt components and shift components of the anti-vibration lens group in each example. FIG. 2 is a schematic diagram of an imaging device in each example.

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

1, 5, 9, 13, and 17 are cross-sectional views of the optical system LO when focusing on infinity in Examples 1 to 5, respectively. The optical system LO in each embodiment is an optical system used in an imaging device such as a digital video camera, digital still camera, broadcasting camera, silver halide film camera, or surveillance camera, but is not limited thereto. do not have.

In FIGS. 1, 5, 9, 13, and 17, the left side is the object side, and the right side is the image side. The optical system LO of each example consists of a plurality of lens groups. In the optical systems LO of Examples 1 to 3 and Example 5, the lens group is a group of lenses that move or remain stationary as a unit during image blur correction. In the optical system LO of Example 4, the lens group is a group of lenses that move or stand still during zooming or image blur correction. Note that the lens group may be composed of one lens or a plurality of lenses. Further, the lens group may include an aperture stop.

In FIGS. 1, 5, 9, 13, and 17, Li represents the i-th lens group (i is a natural number) counting from the object side among the lens groups. SP is an aperture stop. IP is an image plane, and when the optical system LO of each embodiment is used as an imaging optical system for a digital still camera or a digital video camera, IP is an image plane for imaging a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or a CMOS sensor. The plane is placed. On the other hand, when the optical system LO of each embodiment is used as an imaging optical system of a silver halide film camera, a photosensitive surface corresponding to the film surface is placed on the image plane IP.

2, 6, 10, 14, and 18 are longitudinal aberration diagrams of the optical systems LO of Examples 1 to 5, respectively. In the spherical aberration diagram, Fno is the F number and indicates the amount of spherical aberration for the d-line (wavelength 587.56 nm) and the g-line (wavelength 435.835 nm). In the astigmatism diagram, S indicates a sagittal image plane, and M indicates a meridional image plane. The distortion diagram shows the amount of distortion for the d-line. The chromatic aberration diagram shows the amount of lateral chromatic aberration at the g-line. ω is a half angle of view (degrees) calculated by paraxial calculation.

3, 7, 11, 15, and 19 are lateral aberration diagrams of the optical systems LO of Examples 1 to 5, respectively. 4, 8, 12, 16, and 20 are lateral aberration diagrams of the optical systems LO of Examples 1 to 5 during image blur correction, respectively. In each figure, d-line and g-line aberration diagrams are shown in order from the top at 100% of the positive image height, 70% of the positive image height, the center, 70% of the negative image height, and 100% of the negative image height. The broken line S(d) represents the sagittal image surface of the d-line, the solid line M(d) represents the meridional image surface of the d-line, and the two-dot chain line M(g) represents the meridional image surface of the g-line.

Next, the characteristic configuration of the optical system LO of each embodiment will be described. The optical system LO of each embodiment includes, in order from the object side to the image side, a front group, an anti-vibration lens group, and a rear group. The front group consists of all lenses (one or more lenses) arranged closer to the object side than the anti-vibration lens group. The rear group consists of all lenses arranged closer to the image side than the anti-vibration lens group. The anti-shake lens group performs image blur correction by moving to include a shift component and a tilt component. Here, the shift component is a component in the direction perpendicular to the optical axis OA, and the tilt component is a component in the rotation direction in a plane consisting of the optical axis direction and the direction perpendicular to the optical axis OA.

By arranging the lens groups before and after the anti-vibration lens group, the anti-vibration lens group can be made smaller. Furthermore, the height of off-axis rays incident on the anti-vibration lens group can be suppressed, making it easy to suppress decentering aberrations. In addition, the anti-vibration lens group corrects image blur by moving to include the shift component and tilt component, so that the decentering aberration remaining after image blur correction due to the shift of the anti-vibration lens group can be corrected by adjusting the tilt of the anti-vibration lens group. It is possible to correct the decentering aberration caused by.

The optical system LO of each example satisfies the following conditional expression (1).

|α2/α1|<0.460...(1)
Conditional expression (1) defines the absolute value of the ratio of the inclination angle α1 of the paraxial axial ray entering the anti-vibration lens group to the inclination angle α2 of the paraxial axial ray exiting from the anti-vibration lens group. Here, a paraxial ray is defined as a ray that is incident at a position where the height h1 from the optical axis on the surface closest to the object side of the optical system is 1 when the focal length of the entire optical system is normalized to 1. It is an axial ray. FIG. 21 is an explanatory diagram of the inclination angle α1 of the paraxial axial ray entering the anti-vibration lens group and the inclination angle α2 of the paraxial axial ray exiting from the anti-vibration lens group. In FIG. 21, the sign of the inclination angle is positive when counterclockwise with respect to the optical axis OA.

Hereinafter, the meaning of conditional expression (1) will be explained for cases where the refractive power of the anti-vibration lens group is positive and when the refractive power is negative. First, a case where the anti-vibration lens group has positive refractive power will be explained. When the inclination angle α1 of the paraxial axial ray is positive and the inclination angle α2 of the paraxial axial ray is positive, if the inclination angle α2 of the paraxial axial ray becomes larger than the upper limit of conditional expression (1), the anti-vibration lens The refractive power of the group is too small, reducing the effect of image blur correction.

When the inclination angle α1 of the paraxial axial ray is positive and the inclination angle α2 of the paraxial axial ray is negative, when the absolute value of the inclination α2 of the paraxial ray exceeds the upper limit of conditional expression (1), The refractive power of the anti-vibration lens group increases. As a result, the number of lenses in the anti-vibration lens group increases, which is not preferable. Furthermore, decentering aberrations such as decentering coma aberration and image plane tilting tend to occur during image blur correction.

When the inclination angle α1 of the paraxial axial ray is negative and the inclination angle α2 of the paraxial axial ray is negative, the value of conditional expression (1) becomes larger than 1.00 and exceeds the upper limit. At this time, the refractive powers of the front group and the anti-vibration lens group have the same sign, making it difficult to ensure sufficient shift sensitivity of the anti-vibration lens group. Note that when the refractive power of the anti-vibration lens group is positive, the inclination angle α1 of the paraxial axial ray is never negative and the inclination angle α2 of the paraxial axial ray is never positive.

Next, a case where the anti-vibration lens group has negative refractive power will be described. When the inclination α1 of the paraxial ray is negative and the inclination α2 of the paraxial ray is negative, when the absolute value of the inclination α2 of the paraxial ray exceeds the upper limit of conditional expression (1), The refractive power of the anti-vibration lens group is too small. As a result, the effect of image blur correction becomes smaller, which is not preferable.

When the inclination angle α1 of the paraxial ray is negative and the inclination angle α2 of the paraxial ray is positive, if the inclination angle α2 of the paraxial ray is too large exceeding the upper limit of conditional expression (1), image stabilization The refractive power of the lens group increases. As a result, the number of lenses constituting the anti-vibration lens group increases, which is not preferable. Furthermore, decentering aberrations such as decentering coma aberration and image plane tilting tend to occur during image blur correction.

When the inclination angle α1 of the paraxial axial ray is positive and the inclination angle α2 of the paraxial axial ray is positive, the value of conditional expression (1) becomes larger than 1.00 and exceeds the upper limit value. At this time, the refractive powers of the front group and the anti-vibration lens group have the same sign, making it difficult to ensure sufficient shift sensitivity of the anti-vibration lens group. Note that when the refractive power of the anti-vibration lens group is negative, the inclination angle α1 of the paraxial axial ray will not be positive and the inclination angle α2 of the paraxial axial ray will not be negative.

Preferably, the numerical range of conditional expression (1) is set so as to satisfy conditional expression (1a) below.

|α2/α1|<0.455...(1a)
By satisfying conditional expression (1a), the number of lenses in the anti-vibration lens group can be kept to a small number, shift sensitivity can be easily ensured, and decentering aberrations due to shifts in the anti-vibration lens group can be suppressed.

More preferably, the numerical range of conditional expression (1) is set so as to satisfy conditional expression (1b) below.

|α2/α1|<0.450...(1b)
By satisfying conditional expression (1b), decentering aberrations that occur when the anti-vibration lens group is shifted can be suppressed to some extent and can be easily canceled by eccentric aberrations caused by tilting the anti-vibration lens group.

Furthermore, the optical system LO of each example is based on the following conditional expression (2), where Y is the shift component of the anti-shake lens group, θ is the tilt component of the anti-shake lens group, and fis is the focal length of the anti-shake lens group. satisfy.

0.11<|Y/(fis×sinθ)|<1.15 (2)
Conditional expression (2) defines the absolute value of the ratio of the tilt component θ to the arbitrary shift component Y of the image stabilizing lens group in image blur correction. Note that the tilt component θ is an angle between the center line of the anti-vibration lens group and the optical axis OA, and the clockwise direction is positive. The optical system LO of each embodiment satisfies conditional expression (2) at one or more positions where a predetermined image blur correction angle of 0.1 degrees or more is achieved during image blur correction.

Here, with reference to FIG. 23, the shift component Y and tilt component θ in each example will be explained. FIG. 23 is an explanatory diagram of the tilt component and shift component of the anti-shake lens group, and shows the anti-shake lens group that has been moved for image blur correction. At this time, the shift component Y of the anti-vibration lens group is determined by the shift component Y from the point P on the center line of the anti-vibration lens group (double-dashed line in FIG. 23) on the surface closest to the object side of the anti-vibration lens group. This is the length of a perpendicular line drawn down to the optical axis OA (dotted chain line in FIG. 23) when the object is not moving. In addition, the tilt component θ of the anti-vibration lens group is determined between the center line of the anti-vibration lens group (double-dashed line in FIG. 23) and the optical axis OA when the anti-vibration lens group is not moving (the one-dot chain line in FIG. 23). is the angle formed by The tilt component is positive in the clockwise direction when the object side of the optical system is the left side and the image side is the right side. The center line of the anti-vibration lens group is defined as the point located on the optical axis of the surface of the anti-vibration lens group closest to the object side when the anti-vibration lens group is not moving for image stabilization. This is a straight line connecting points located on the optical axis of the image-side surface of the anti-vibration lens group.

If the tilt component θ of the anti-vibration lens group is too small relative to the shift component Y, exceeding the upper limit of conditional expression (2), the eccentric aberration caused by the tilt component θ will be smaller than the eccentric aberration caused by the shift component Y. too small. As a result, the effect of reducing decentering aberration during image stabilization becomes smaller, which is not preferable. On the other hand, if the lower limit of conditional expression (2) is exceeded and the tilt component θ of the anti-vibration lens group is too large relative to the shift component Y, the eccentric aberration caused by the tilt component θ becomes the eccentric aberration caused by the shift component Y. Too big for that. As a result, decentering aberration caused by the shift component Y of the anti-vibration lens group cannot be canceled well.

Preferably, the numerical range of conditional expression (2) is set so as to satisfy conditional expression (2a) below.

0.15<|Y/(fis×sinθ)|<1.14...(2a)
By satisfying conditional expression (2a), the effect of reducing decentering aberration is successful, and it becomes easier to enlarge the image blur correction angle.

More preferably, the numerical range of conditional expression (2) is set so as to satisfy conditional expression (2b) below.

0.18<|Y/(fis×sinθ)|<1.13...(2b)
By satisfying conditional expression (2b), the accuracy required for the tilt component θ of the anti-vibration lens group becomes low, and driving becomes easy. Note that when the optical system LO has a plurality of anti-vibration lens groups, at least one of the plurality of anti-vibration lens groups only needs to satisfy conditional expressions (1) and (2).

According to each embodiment, it is possible to provide an optical system that can realize high optical performance while enlarging the image blur correction angle when correcting image blur.

Preferably, the anti-vibration lens group in each embodiment consists of a single lens or a cemented lens. With such a configuration, the anti-vibration lens group can be made lightweight and compact.

In each example, in the case of a single focal length lens, the focal length of the optical system LO is f, and from the first surface (the lens surface closest to the object side of the optical system LO) to the final surface (the lens surface of the optical system LO Let L be the distance to the lens surface (most image side). In each embodiment, in the case of a zoom lens, the focal length of the optical system LO at any zoom position is f, and the distance from the first surface to the final surface of the lens constituting the optical system LO for the focal length f is L. . In addition, the distance from the aperture stop SP to the apex of the lens closest to the aperture stop in the anti-vibration lens group is Lsp, the shift sensitivity of the anti-vibration lens group when focusing on infinity is SA, and the focal length of the front group is f1. , the focal length of the rear group is f2. At this time, it is preferable that the optical system LO of each embodiment satisfies at least one of the following conditional expressions (3) to (7).

1.00<|fis|/f<8.00...(3)
0.001<Lsp/L<0.200...(4)
0.20<|SA|<0.60...(5)
-1.20<f1/fis<-0.10...(6)
0.40<|f1/f2|<2.00...(7)
The shift sensitivity SA represents the amount of movement of the center of the image with respect to the unit shift component of the anti-vibration lens group, and when the lateral magnification of the anti-vibration lens group is βA and the lateral magnification of the rear group is βR, the following Formula (A) holds true.

SA=(1-βA)βR...(A)
Next, the technical meanings of conditional expressions (3) to (7) will be explained. Conditional expression (3) is an expression that defines the ratio between the absolute value of the focal length fis of the anti-shake lens group and the focal length f of the optical system LO. When the focal length fis of the anti-shake lens group becomes longer than the upper limit of conditional expression (3), that is, when the absolute value of the refractive power of the anti-shake lens group becomes smaller, the image blur correction by the shift component Y and the tilt component θ becomes The effect becomes smaller. As a result, when the shift component Y and the tilt component θ are increased to obtain a desired image blur correction angle, the drive mechanism for the anti-shake lens group becomes larger. On the other hand, when the focal length fis of the anti-vibration lens group becomes shorter by exceeding the lower limit of conditional expression (3), that is, when the absolute value of the refractive power increases, the number of lenses constituting the anti-vibration lens group increases.

Conditional expression (4) is an expression that defines the positions of the aperture stop SP and the anti-vibration lens group with respect to the entire length of the optical system LO. When the vibration-proof lens group moves away from the aperture stop SP beyond the upper limit of conditional expression (4), the position at which the off-axis light beam is refracted by the vibration-proof lens group becomes higher. As a result, aberration fluctuations in the off-axis light beam during image stabilization, such as eccentric astigmatism and image tilt, occur frequently. On the other hand, if the lower limit of conditional expression (4) is exceeded and the anti-vibration lens group becomes closer to the aperture stop SP, it is not preferable because the layout of the members constituting the drive mechanism of the anti-vibration lens group becomes difficult.

Conditional expression (5) is an expression that defines the shift sensitivity SA of the anti-vibration lens group. When shift sensitivity SA increases beyond the upper limit of conditional expression (5), the number of lenses forming the anti-vibration lens group increases. On the other hand, when the shift sensitivity SA becomes smaller by exceeding the lower limit of conditional expression (5), the effect of image blur correction by the shift component Y becomes smaller. As a result, if the shift component Y is increased to obtain the desired image blur correction angle, the drive mechanism for the anti-shake lens group becomes larger. Furthermore, since the eccentric aberration caused by the shift component Y also increases, in order to reduce the eccentric aberration, it is necessary to increase the eccentric aberration (sensitivity to eccentric aberration of tilt) that occurs per unit tilt component. As a result, the number of lenses increases.

Conditional expression (6) is an expression that defines the ratio between the focal length f1 of the front group and the focal length fis of the anti-vibration lens group. By setting the refractive powers of the front group and the anti-vibration lens group to have opposite signs, it becomes easier to ensure the shift sensitivity SA of the anti-vibration lens group. When the focal length f1 of the front group becomes shorter by exceeding the upper limit of conditional expression (6), that is, when the absolute value of the refractive power increases, the way the rays pass through the front group during image blur correction becomes non-eccentric. Since the angle changes greatly compared to , decentering aberrations are more likely to occur. As a result, the number of lenses in the anti-vibration lens group increases in order to correct eccentric aberrations. On the other hand, when the focal length f1 of the front group increases beyond the lower limit of conditional expression (6), that is, when the absolute value of the refractive power decreases, the total length of the front group increases, and the distance between the front lens and the anti-vibration lens group increases. The distance becomes longer. As a result, it becomes difficult to ensure the amount of peripheral light during image blur correction.

Conditional expression (7) is an expression that defines the absolute value of the ratio between the focal length f1 of the front group and the focal length f2 of the rear group. When the focal length f2 of the rear group becomes short beyond the upper limit of conditional expression (7), that is, when the absolute value of the refractive power becomes large, a lot of curvature of field and distortion aberration occur. On the other hand, if the focal length f2 of the rear group increases beyond the lower limit of conditional expression (7), that is, if the absolute value of the refractive power decreases, the total length of the rear group lens increases, making it difficult to downsize the optical system LO. become.

More preferably, the numerical ranges of conditional expressions (3) to (7) are set so as to satisfy the following conditional expressions (3a) to (7a).

1.10<|fis|/f<7.80...(3a)
0.0015<Lsp/L<0.1800...(4a)
0.24<|SA|<0.55...(5a)
-1.10<f1/fis<-0.15...(6a)
0.45<|f1/f2|<1.90...(7a)
More preferably, the numerical ranges of conditional expressions (3) to (7) are set so as to satisfy the following conditional expressions (3b) to (7b).

1.20<|fis|/f<7.60...(3b)
0.0018<Lsp/L<0.1500...(4b)
0.27<|SA|<0.52...(5b)
-1.06<f1/fis<-0.20...(6b)
0.55<|f1/f2|<1.85...(7b)
Next, the optical systems LO of Examples 1 to 5 will be described in detail with reference to FIGS. 1, 5, 9, 13, and 17. FIG. 1 is a cross-sectional view of the optical system LO of Example 1, where L1 is the first lens group with negative refractive power, L2 is the second lens group (anti-vibration lens group) with positive refractive power, and L3 is the positive refractive power. The third lens group has a refractive power of . 5 and 9 are cross-sectional views of the optical systems LO of Examples 2 and 3, respectively, where L1 is the first lens group with positive refractive power, and L2 is the second lens group with negative refractive power. L3 is a third lens group with positive refractive power.

FIG. 13 is a cross-sectional view of the optical system LO of Example 4, in which FIG. 13(A) shows a cross-sectional view at the wide-angle end, FIG. 13(B) shows a cross-sectional view at the middle, and FIG. 13(C) shows a cross-sectional view at the telephoto end. L1 is the first lens group with negative refractive power, L2 is the second lens group (anti-vibration lens group) with positive refractive power, L3 is the third lens group with positive refractive power, and L4 is the third lens group with negative refractive power. There are four lens groups, and L5 is a fifth lens group with negative refractive power. Arrows in FIG. 13 indicate movement trajectories of each lens group and aperture stop SP during zooming from the wide-angle end to the telephoto end. The first lens group L1 and the second lens group L2 are adjacent to each other so that the distance between the third lens group L3 and the fourth lens group L4 is narrower at the telephoto end than at the wide-angle end during zooming. The spacing between lens groups changes. Further, the distance between adjacent lens groups changes so that the distance between the fourth lens group L4 and the fifth lens group L5 increases.

FIG. 17 is a cross-sectional view of the optical system LO of Example 5. L1 is a first lens group with negative refractive power, L2 is a second lens group with positive refractive power, L3 is a third lens group with positive refractive power, and L4 is a fourth lens group with positive refractive power. The optical system LO of Example 5 has two anti-vibration lens groups. One anti-vibration lens group is the second lens group L2 (anti-vibration lens group A), and the other anti-vibration lens group is the third lens group L3 (anti-vibration lens group B). Having two anti-shake lens groups is more effective in expanding the image blur correction angle than image blur correction using only one anti-shake lens group.

Image blur correction is performed by moving the anti-shake lens group to include a shift component Y and a tilt component θ. The configuration at this time will be described with reference to FIG. 22. FIG. 22 is an explanatory diagram of a mechanism (shake-proof mechanism) in which the vibration-proof lens group IS shifts and tilts. The anti-vibration mechanism shown in FIG. 22 has several spheres SB and magnets MG arranged between a lens holder LH that holds an anti-vibration lens group IS and an adjacent fixed member LB, and a fixed member on which the magnet MG is arranged. This is achieved by arranging the coil CL on the member LB. The lens holder LH is configured to be movable by the rolling of the sphere SB with respect to the fixed member LB. By energizing the coil CL, the magnet MG moves, making it possible to move the lens holder LH. In such a configuration, the shape of the receiving surface where the sphere SB contacts the fixing member LB and the lens holder LH is a free-form surface, so that the lens holder LH can be tilted and shifted.

Preferably, the anti-vibration lens group in each embodiment is fixed during focusing. Further, in each embodiment, when the optical system LO is a zoom lens, it is sufficient that each conditional expression is satisfied at at least one point at an arbitrary zoom position.

Numerical Examples 1 to 5 corresponding to Examples 1 to 5, respectively, will be shown below. In the surface data of each numerical example, r (mm) is the radius of curvature of each optical surface, and d (mm) is the axial distance (distance on the optical axis) between the m-th surface and the (m+1)-th surface. represents. However, m is the number of the surface counted from the light incident side. Further, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. In addition, the Abbe number νd of a certain material is when the refractive index at the Fraunhofer line d line (587.56 nm), F line (486.13 nm), and C line (656.27 nm) is Nd, NF, and NC.
νd=(Nd-1)/(NF-NC)
It is expressed as

In each numerical example, the interplanar distance d (mm), focal length (mm), F number, and half angle of view (degrees) calculated by paraxial calculation are based on the fact that the optical system LO of each example focuses on an object at infinity. This is the value when combined. Back focus BF is the distance from the final lens surface to the image plane. The total lens length is the value obtained by adding the back focus to the distance from the first surface (the lens surface closest to the object side of the optical system LO) to the final surface (the lens surface closest to the image side of the optical system LO).

Furthermore, if the optical surface is an aspherical surface, an * symbol is attached to the right side of the surface number. For the aspherical shape, X is the amount of displacement from the surface apex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial radius of curvature, K is the conic constant, A4, A6, When A8, A10, and A12 are aspherical coefficients of each order, they are expressed by the following equation (B).

x=(h ² /R)/[1+{1-(1+K)(h/R) ² } ^1/2 +A4×h ⁴ +A6×h ⁶ +A8×h ⁸ +A10×h ¹⁰ +A12×h ¹² ... (B)
In each numerical example, "e±XX" in each aspheric coefficient means "×10± ^XX ". In each numerical example, α1 is the inclination angle of the paraxial axial ray that enters the anti-vibration lens group, and α2 is the inclination angle of the paraxial axial ray that exits from the anti-vibration lens group. θ is a tilt component of the anti-vibration lens group, and Y is a shift component of the anti-vibration lens group. Furthermore, in each numerical example, the image stabilization lens group data at the time of image blur correction is data at the time of focusing at infinity. Conditional expression (2) is obtained by dividing the shift component Y of the anti-shake lens group by the product of the focal length fis of the anti-shake lens group and the sine of the tilt component θ of the anti-shake lens group. SA is the shift sensitivity of the anti-vibration lens group. Table 1 shows the values of conditional expressions (1) to (7) in the optical systems LO of Numerical Examples 1 to 3, and conditional expressions (1) to (7) in the optical systems LO of Numerical Examples 4 and 5. The values are shown in Table 2.

[Numerical Example 1]
Unit: mm

Surface data surface number rd nd νd
1* 25.778 3.00 1.58313 59.4
2* 14.334 8.67
3 42.136 1.80 1.49700 81.5
4 13.966 12.14
5 -13.007 3.12 1.75500 52.3
6 -14.733 0.24
7 -88.677 4.21 1.80100 35.0
8 -15.482 1.20 1.84666 23.8
9 -35.267 0.46
10 113.729 1.91 1.49700 81.5
11 -200.300 4.11
12(Aperture) ∞ 5.33
13 21.351 1.44 1.83400 37.2
14 9.989 8.74 1.70154 41.2
15 33.763 1.31
16 -913.357 3.49 1.69350 50.8
17 -24.726 0.18
18 59.421 8.18 1.43875 94.7
19 -14.634 0.24
20 -17.729 1.20 1.91082 35.3
21 -112.201 4.80 1.49700 81.5
22 -18.595 0.18
23* -19.056 2.04 1.80625 40.9
24* -66.652
Image plane ∞

Aspheric data 1st surface
K =-7.33886e-001 A 4= 6.34554e-005 A 6=-1.50022e-007 A 8= 1.48336e-012
A10=2.49677e-013 A12=-2.26276e-016

2nd side
K =-2.24737e-001 A 4= 7.06793e-005 A 6= 3.02160e-007 A 8=-4.96095e-009
A10=2.23080e-011 A12=-5.33308e-014

Page 23
K =-6.77869e+000 A 4=-1.44584e-004 A 6= 7.46612e-007 A 8=-4.55455e-009
A10=9.73318e-012 A12=-1.27174e-014

Page 24
K =-1.75312e+002 A 4=-4.17944e-005 A 6= 8.05745e-007 A 8=-5.49068e-009
A10=2.14468e-011 A12=-3.60226e-014

Focal length 19.50
F number 2.88
Half angle of view (degrees) 47.99
Image height 21.65
Lens total length 96.33
BF 18.34

Lens group data group Starting surface Focal length
1 1 -67.60
2 10 146.25
3 12 39.79

Anti-vibration lens group data during image stabilization

Anti-vibration lens group Starting surface number 10 Ending surface number 11
Anti-vibration lens group Focal length fis 146.25mm
Inclination angle α1 of the paraxial ray incident on the anti-vibration lens group -0.290
Inclination angle α2 of paraxial rays emerging from the anti-vibration lens group -0.014

Image stabilization angle 0.500 degrees
Tilt component θ of anti-vibration lens group -0.800 degrees
Shift component Y of anti-vibration lens group 0.618mm
Anti-vibration sensitivity SA of anti-vibration lens group 0.275

[Numerical Example 2]
Unit: mm

Surface data surface number rd nd νd
1 1492.754 3.38 1.60311 60.6
2 -168.581 0.30
3 45.913 6.49 1.49700 81.5
4 115.344 13.13
5 39.271 4.16 1.59282 68.6
6 146.136 1.42
7 -300.468 1.56 1.72825 28.5
8 40.547 5.76
9(Aperture) ∞ 2.14
10 64.630 3.16 1.90043 37.4
11 -234.532 2.00
12 -193.526 1.20 1.72825 28.5
13 68.929 3.65
14 -1318.681 3.03 1.92286 20.9
15 -48.641 0.93 1.72047 34.7
16 56.947 2.59
17 -211.380 5.45 1.63854 55.4
18 -30.720 1.40
19 -24.331 1.60 1.51742 52.4
20 281.262 0.20
21 57.703 10.33 1.77250 49.6
22 -39.064 8.71
23 -26.909 1.70 1.72825 28.5
24 -64.741
Image plane ∞

Focal length 82.88
F number 1.86
Half angle of view (degrees) 14.63
Image height 21.64
Lens total length 107.79
BF 23.52

Lens group data group Starting surface Focal length
1 1 114.51
2 14 -108.98
3 17 63.26

Anti-vibration lens group data during image stabilization

Anti-vibration lens group Starting surface number 14 Ending surface number 16
Anti-vibration lens group Focal length fis -108.980mm
Inclination angle α1 of paraxial rays incident on the anti-vibration lens group 0.724
Inclination angle α2 of paraxial rays emerging from the anti-vibration lens group 0.325

Image stabilization angle -0.500 degrees
Tilt component θ of anti-vibration lens group -0.850 degrees
Shift component Y of anti-vibration lens group 1.813mm
Anti-vibration sensitivity SA of anti-vibration lens group -0.399

[Numerical Example 3]
Unit: mm

Surface data surface number rd nd νd
1 140.553 15.87 1.48749 70.2
2 -161.275 0.10
3 85.683 11.42 1.49700 81.5
4 -1913.514 1.49
5 -242.484 5.77 1.80610 40.9
6 425.272 0.26
7 81.991 7.14 1.49700 81.5
8 33.849 1.02
9 35.684 8.51 1.58267 46.4
10 41.802 18.00
11 -60.243 5.01 1.80518 25.4
12 -53.684 1.34 1.63930 44.9
13 -106.817 0.26
14(Aperture) ∞ 3.00
15 136.907 4.00 1.80518 25.4
16 60.062 2.20 1.63930 44.9
17 64.062 29.00
18 -194.701 1.00 1.68893 31.1
19 121.767 4.00 1.78590 44.2
20 -57.401
Image plane ∞

Focal length 190.00
F number 4.26
Half angle of view (degrees) 6.50
Image height 21.64
Lens total length 244.53
BF 125.14

Lens group data group Starting surface Focal length
1 1 223.81
2 11 -256.14
3 14 151.15

Anti-vibration lens group data during image stabilization

Anti-vibration lens group Starting surface number 11 Ending surface number 13
Anti-vibration lens group Focal length fis -256.141mm
Inclination angle α1 of paraxial rays incident on the anti-vibration lens group 0.849
Inclination angle α2 of paraxial rays emerging from the anti-vibration lens group 0.376

Image stabilization angle -0.500 degrees
Tilt component of anti-vibration lens group θ 4.250 degrees
Shift component Y of anti-vibration lens group 3.514mm
Anti-vibration sensitivity SA of anti-vibration lens group -0.473

[Numerical Example 4]
Unit: mm

Surface data surface number rd nd νd
1* 64.247 2.70 1.58388 59.1
2* 9.511 8.69
3 -55.630 1.20 1.72916 54.7
4 15.737 3.05
5 24.940 4.30 1.91082 35.3
6 -198.555 (variable)
7 303.924 2.80 1.48749 70.2
8 -38.077 5.01
9(Aperture) ∞ 0.40
10 15.588 4.75 1.58144 40.8
11 -14.684 0.80 1.88300 40.8
12 18.969 0.69
13 12.399 5.10 1.49700 81.5
14 -16.977 0.81
15 37.611 4.15 1.48749 70.2
16 -9.315 1.30 1.85135 40.1
17* -25.444 (variable)
18 28.224 0.80 1.83481 42.7
19 17.098 (variable)
20 2052.642 6.55 1.59270 35.3
21 -10.988 1.10 1.83481 42.7
22 -54.394 (variable)
Image plane ∞

Aspheric data 1st surface
K = 0.00000e+000 A 4= 3.14090e-005 A 6=-8.34213e-008 A 8= 9.34004e-011
A10=2.56473e-014

2nd side
K =-9.41229e-001 A 4= 8.96367e-005 A 6= 2.85953e-007 A 8= 3.04254e-009
A10=-2.36310e-011

Page 17
K = 0.00000e+000 A 4= 5.21559e-005 A 6= 2.06781e-007 A 8= 1.56671e-008
A10=-1.24926e-010

Various data Zoom ratio 1.91

Focal length 10.83 13.48 20.68
F number 4.10 4.52 5.72
Half angle of view (degrees) 51.59 45.38 33.44
Image height 13.66 13.66 13.66
Lens total length 89.25 86.77 88.08
BF 9.86 13.52 23.58

d 6 16.99 10.86 2.09
d17 1.30 0.90 0.08
d19 6.91 7.31 8.12
d22 9.86 13.52 23.58

Zoom lens group data group Starting plane Focal length
1 1 -16.74
2 7 69.60
3 9 22.21
4 18 -53.71
5 20 -161.54

Anti-vibration lens group data during image stabilization

Anti-vibration lens group Starting surface number 7 Ending surface number 8
Anti-vibration lens group Focal length fis 69.535mm
Inclination angle α1 of paraxial rays incident on the anti-vibration lens group
Wide-angle end Intermediate Telephoto end
-0.647 -0.805 -1.236
Inclination angle α2 of paraxial rays emerging from the anti-vibration lens group
Wide-angle end Intermediate Telephoto end
-0.153 -0.262 -0.557

Image stabilization angle 0.500 degrees
Tilt component θ of anti-vibration lens group -0.300 degrees
Shift component Y of anti-vibration lens group 0.191mm
Anti-vibration sensitivity SA of anti-vibration lens group 0.494

[Numerical Example 5]
Unit: mm

Surface data surface number rd nd νd
1* 25.799 3.00 1.58313 59.4
2* 14.353 8.62
3 42.435 1.80 1.49700 81.5
4 13.938 11.99
5 -13.006 3.12 1.75500 52.3
6 -14.732 0.88
7 -88.460 4.15 1.80100 35.0
8 -15.464 1.20 1.84666 23.8
9 -35.220 0.96
10 119.680 1.52 1.49700 81.5
11 -184.576 4.11
12(Aperture) ∞ 5.22
13 21.386 1.44 1.83400 37.2
14 10.002 8.89 1.70154 41.2
15 34.045 1.32
16 -858.400 3.51 1.69350 50.8
17 -24.726 0.18
18 59.439 8.17 1.43875 94.7
19 -14.647 0.24
20 -17.725 1.20 1.91082 35.3
21 -132.341 4.42 1.49700 81.5
22 -19.120 0.18
23* -19.594 2.04 1.80625 40.9
24* -67.329
Image plane ∞

Aspheric data 1st surface
K =-7.27796e-001 A 4= 6.37865e-005 A 6=-1.52082e-007 A 8= 6.59829e-012
A10=2.57397e-013 A12=-2.13988e-016

2nd side
K =-2.24737e-001 A 4= 7.13132e-005 A 6= 2.94391e-007 A 8=-4.91025e-009
A10=2.22426e-011 A12=-5.19773e-014

Page 23
K =-6.85301e+000 A 4=-1.38447e-004 A 6= 6.74494e-007 A 8=-3.61748e-009
A10=4.65118e-012 A12=-5.58396e-015

Page 24
K =-1.80652e+002 A 4=-4.33057e-005 A 6= 7.97487e-007 A 8=-5.17980e-009
A10= 1.94805e-011 A12=-3.19474e-014

Focal length 19.29
F number 2.86
Half angle of view (degrees) 48.30
Image height 21.65
Lens total length 96.59
BF 18.43

Lens group data group Starting surface Focal length
1 1 -24.24
2 7 78.99
3 10 146.33
4 12 40.05

Anti-vibration lens group data during image stabilization

Anti-vibration lens group A Starting surface number 7 Ending surface number 9
Anti-vibration lens group A Focal length fis 78.992mm
Inclination angle α1 of the paraxial ray incident on the anti-vibration lens group -0.041
Inclination angle α2 of paraxial rays emerging from anti-vibration lens group -0.015

Anti-vibration lens group B Starting surface number 10 Ending surface number 11
Anti-vibration lens group B Focal length fis 146.327mm
Inclination angle α1 of paraxial rays incident on the anti-vibration lens group -0.015
Inclination angle α2 of paraxial rays emerging from the anti-vibration lens group -0.000

Image stabilization angle 1.000 degrees
Tilt component θ of anti-vibration lens group A 0.600 degrees
Shift component Y of anti-vibration lens group A 0.655mm
Anti-vibration sensitivity SA of anti-vibration lens group A 0.514
Tilt component θ of anti-vibration lens group B -1.200 degrees
Shift component Y of anti-vibration lens group B 0.611mm
Anti-vibration sensitivity SA of anti-vibration lens group B 0.276

[Imaging device]
Next, with reference to FIG. 24, a digital still camera (imaging device) using the optical system LO of each example as an imaging optical system will be described. FIG. 24 is a schematic diagram of the imaging device 10.

In FIG. 24, 13 is a camera body, and 11 is an imaging optical system constituted by any of the optical systems LO described in Examples 1 to 5. Reference numeral 12 denotes an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor, which is built into the camera body and receives an optical image formed through the imaging optical system 11 and converts it into electricity. The camera body 13 may be a so-called single-lens reflex camera with a quick return mirror, or a so-called mirrorless camera without a quick return mirror. Note that this embodiment is not limited to an imaging device that includes a camera body and an imaging optical system (interchangeable lens) that can be attached to and detached from the camera body. It is also applicable to other imaging devices. In this way, by applying the optical system LO of each embodiment to an imaging device such as a digital still camera, an imaging device with a compact lens can be obtained.

According to each embodiment, it is possible to provide an optical system and an imaging device that can achieve high optical performance while enlarging the image blur correction angle when correcting image blur.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the invention.

LO Optical system L2 2nd lens group (anti-vibration lens group)

Claims (9)

An optical system having an anti-vibration lens group and an aperture stop ,
The anti-shake lens group is composed of one single lens or one cemented lens, and moves to include a shift component and a tilt component to correct image blur;
α1 is the inclination angle of the paraxial axial ray entering the anti-vibration lens group, α2 is the inclination angle of the paraxial ray exiting from the anti-vibration lens group, Y is the shift component of the anti-vibration lens group, The tilt component of the vibration-proof lens group is θ, the focal length of the vibration-proof lens group is fis, and the light from the aperture stop to the apex of the surface on the aperture-stop side of the lens disposed closest to the aperture stop in the vibration-proof lens group When the on-axis distance is Lsp, and the distance from the lens surface closest to the object side of the optical system to the lens surface closest to the image side of the optical system is L,
|α2/α1|<0.460
0.11<|Y/(fis×sinθ)|<1.15
0.052≦Lsp/L<0.200
An optical system characterized by satisfying the following conditional expression. When the focal length of the optical system is f,
1.00<|fis|/f<8.00
The optical system according to claim 1, wherein the optical system satisfies the following conditional expression. When the shift sensitivity of the anti-vibration lens group when focusing at infinity is SA,
0.20<|SA|<0.60
3. The optical system according to claim 1, wherein the optical system satisfies the following conditional expression. further comprising a front group consisting of all lenses arranged closer to the object side than the anti-vibration lens group,
When the focal length of the front group is f1,
-1.20<f1/fis<-0.10
4. The optical system according to claim 1, wherein the optical system satisfies the following conditional expression. further comprising a rear group consisting of all lenses arranged closer to the image side than the anti-vibration lens group,
When the focal length of the rear group is f2,
0.40<|f1/f2|<2.00
5. The optical system according to claim 1, wherein the optical system satisfies the following conditional expression. 6. The optical system according to claim 1, wherein the image stabilizing lens group is fixed during focusing. 0.029≦｜α2/α1｜<0.460
7. The optical system according to claim 1, wherein the optical system satisfies the following conditional expression. The optical system according to any one of claims 1 to 7, wherein the optical system includes a negative meniscus lens with a convex surface facing the image side, which is arranged on the image side of the image stabilizing lens group. . The optical system according to any one of claims 1 to 8,
An imaging device comprising: an imaging element that photoelectrically converts an optical image formed through the optical system.