JP6566661B2 - Zoom lens and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable for an image pickup apparatus such as a still camera, a video camera, a digital still camera, and a surveillance camera.

  In recent years, imaging devices have become more sophisticated, and the entire device has been downsized. An imaging optical system used therefor is required to be a zoom lens with a short overall lens length, a small overall system, and a high zoom ratio. Further, there is a demand for a zoom lens using a focusing method that can perform high-speed autofocus.

  As a focusing method, the inner focus type zoom lens has a smaller effective diameter of the focus lens group than a zoom lens that moves the first lens group to perform focusing, and the entire lens system can be easily downsized. Further, close-up photography, particularly close-up photography is facilitated. Further, since the small and light lens group is moved, the driving force of the lens group is small, and quick focusing is easy.

  Conventionally, in order from the object side to the image side, a zoom lens using an inner focus type, which includes a first lens group to a third lens group having positive, negative, and positive refractive power and a subsequent lens group including one or more lens groups. Lenses are known (Patent Documents 1 and 2). In Patent Document 1, focusing is performed by the fourth lens group, and image blurring that occurs when the zoom lens vibrates is performed by a partial group of the third lens group. In Patent Document 2, focusing is performed by the second lens group, and image blur correction is performed by a partial group of the third lens group.

JP 2014-98795 A Japanese Unexamined Patent Publication No. 2011-170086

In recent years, there is a strong demand for a zoom lens used in an imaging apparatus to be a zoom lens having a wide angle of view, a high zoom ratio, a compact lens system, and high resolution .

In a zoom lens, it is important to appropriately set each element of the zoom lens in order to obtain a small optical system and high optical performance while ensuring a high zoom ratio. For example, the zoom type (the number of lens groups and the refractive power of each lens group), the movement trajectory associated with zooming of each lens group, the variable magnification burden of each lens group, and the configuration of the lens group for image blur correction are set appropriately It becomes important to do.

If these configurations are not appropriate, the entire system may become large when a high zoom ratio is achieved, and variations in various aberrations associated with zooming may increase.

SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens capable of correcting image blur while being small in size, and easily obtaining good optical performance, and an image pickup apparatus having the zoom lens.

The zoom lens according to the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and one or more lens groups, which are arranged in order from the object side to the image side. intermediate group refractive power, in the negative lens group NF refractive power, positive zoom lens spacing varying lens group adjacent zooming consists lens PL refractive power,
The intermediate group is arranged in order from the object side to the image side, and moves in a direction having a component in a direction perpendicular to the optical axis when correcting image blur, and having a positive refractive power subgroup P1 that does not move during image blur correction. It consists of a negative refractive power subgroup N1 and a positive refractive power subgroup P2 that does not move for image blur correction.
The partial group N1 includes one positive lens N1p and one negative lens N1n.
During zooming, the focal lengths of the subgroup N1 and the subgroup P2 do not change,
The lateral magnification of the partial group N1 when focused at infinity at the wide angle end is βnw, and the lateral magnification of the optical system arranged on the image side from the partial group N1 when focused at infinity at the wide angle end When the magnification is βlw, the focal length of the subgroup P2 is fP2, the focal length of the subgroup N1 is fN1, the Abbe number of the material of the positive lens N1p is νn1p, and the Abbe number of the material of the negative lens N1n is νn1n. ,
−3.0 <(1−βnw) × βlw <−1.5
0.5 <| fN1 / fP2 | <0.9
1.5 <νn1n / νn1p <3.2
It is characterized by satisfying the following conditional expression.

According to the present invention, it is possible to correct an image blur while being small, and a zoom lens with higher optical performance can be easily obtained.

Lens cross-sectional view at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 1 (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 1. (A), (B) Lateral aberration diagrams after image position change of 0.3 degrees at the wide-angle end and the telephoto end of Example 1. Cross-sectional view of the lens at the wide-angle end, the intermediate zoom position, and the telephoto end in Example 2 (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 2. (A), (B) Lateral aberration diagrams after image position change of 0.3 degrees at the wide-angle end and the telephoto end of Example 2. Lens cross-sectional view at the wide-angle end, the intermediate zoom position, and the telephoto end of Embodiment 3 (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 3. (A), (B) Lateral aberration diagrams after image position change of 0.3 degrees at the wide-angle end and the telephoto end in Example 3 Schematic diagram of main parts of an imaging apparatus of the present invention

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The zoom lens of the present invention is as follows in order from the object side to the image side. A first lens group having a positive refractive power (optical power = reciprocal of focal length), a second lens group having a negative refractive power, an intermediate group having a positive refractive power as a whole, including one or more lens groups, a negative It has a lens group NF having a refractive power and a lens group PL having a positive refractive power. The distance between adjacent lens units changes during zooming.

  1A, 1B, and 1C are lens cross-sectional views at the wide-angle end (short focal length end), the intermediate zoom position, and the telephoto end (long focal length end) of the zoom lens according to Embodiment 1 of the present invention. is there. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the first exemplary embodiment. FIGS. 3A and 3B are lateral aberration diagrams after image blur correction of 0.3 degrees at the wide-angle end and the telephoto end of the zoom lens of Example 1, respectively. The first embodiment is a zoom lens having a zoom ratio of 4.76 and an aperture ratio (F number) of about 4.12 to 5.80.

  4A, 4B, and 4C are lens cross-sectional views at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 5A, 5B, and 5C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 2, respectively. FIGS. 6A and 6B are lateral aberration diagrams after image blur correction of 0.3 degrees at the wide-angle end and the telephoto end of the zoom lens of Example 2, respectively. The second exemplary embodiment is a zoom lens having a zoom ratio of 4.66 and an aperture ratio of about 4.12 to 5.88.

  7A, 7B, and 7C are lens cross-sectional views at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 8A, 8B, and 8C are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively. FIGS. 9A and 9B are lateral aberration diagrams after image blur correction of 0.3 degrees at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 3, respectively. The third embodiment is a zoom lens having a zoom ratio of 4.15 and an aperture ratio of 4.12. FIG. 10 is a schematic view of the main part of the imaging apparatus of the present invention.

  The zoom lens of each embodiment is an imaging optical system used in an imaging apparatus such as a video camera, a digital still camera, a silver salt film camera, or a TV camera. In addition, the zoom lens of each embodiment can also be used as a projection optical system for a projection apparatus (projector). In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens cross-sectional view, when i is the order of the lens group from the object side, Li indicates the i-th lens group.

  GP includes one or more lens groups, and is an intermediate group having a positive refractive power as a whole. NF is a lens unit having a negative refractive power. PL is a lens unit having a positive refractive power. SP is an aperture stop that determines (limits) the light flux of the release F number (Fno). IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is placed. Further, when used as a photographing optical system for a silver salt film camera, a sightseeing surface corresponding to the film surface is placed.

  The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. The arrow related to the focus indicates the moving direction of the lens unit during focusing from infinity to a short distance. In Examples 1 and 3, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a first lens group having a negative refractive power. 4 lens group, L5 is a fifth lens group having negative refractive power, and L6 is a sixth lens group having positive refractive power.

  The intermediate group GP includes a third lens group L3 and a fourth lens group L4. The lens group NF includes a fifth lens group L5. The lens group PL is composed of a sixth lens group L6. The third lens unit L3 includes a partial group P1. The fourth lens unit L4 includes a partial group N1 and a partial group P2. Here, the partial group sometimes constitutes a part of the lens group, and sometimes represents the lens group itself.

  In the zoom lenses of Examples 1 and 3, the first lens unit L1 monotonously moves toward the object side during zooming from the wide-angle end to the telephoto end. The distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is larger than that at the wide-angle end, the interval between the second lens unit L2 and the third lens unit L3 is narrow, and the third lens unit L3 and the fourth lens unit L3. The distance from the lens unit L4 is wide. Each lens group is moved so that the distance between the fourth lens group L4 and the fifth lens group L5 is narrow and the distance between the fifth lens group L5 and the sixth lens group L6 is wide.

  In the zoom lenses of Embodiments 1 and 3, focusing is performed by moving the fifth lens unit L5 on the optical axis. When focusing from an object at infinity to a near object at the zoom position at the telephoto end, it is performed by moving backward (image side) as indicated by an arrow 5c. In the first and third embodiments, the solid curve 5a and the dotted curve 5b relating to the fifth lens unit L5 are used when zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and a short-distance object, respectively. It is a movement locus for correcting image plane fluctuations.

  In Example 2, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, L3 is a third lens group having a positive refractive power, and L4 is a fourth lens having a negative refractive power. The lens group L5 is a fifth lens group having a positive refractive power. The intermediate group GP includes a third lens group L3. The lens group NF includes a fourth lens group L4. The lens group PL is composed of a fifth lens group L5. The third lens unit L3 includes a partial group P1, a partial group N1, and a partial group P2.

  In the zoom lens of Example 2, the first lens unit L1 monotonously moves toward the object side during zooming from the wide-angle end to the telephoto end. The distance between the first lens unit L1 and the second lens unit L2 at the telephoto end is larger than that at the wide-angle end, the interval between the second lens unit L2 and the third lens unit L3 is narrow, and the third lens unit L3 and the fourth lens unit L3. The distance from the lens unit L4 is wide. Further, each lens group is moved so that the distance between the fourth lens group L4 and the fifth lens group L5 is widened.

  In the zoom lens of Example 2, focusing is performed by moving the second lens unit L2 on the optical axis. When focusing from an infinitely distant object to a close object at the zoom position at the telephoto end, it is performed by moving it forward (object side) as indicated by an arrow 2C. In Example 2, the solid curve 2a and the dotted curve 2b relating to the second lens unit L2 are image planes when zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and a short-distance object, respectively. It is a movement locus for correcting the fluctuation.

  In each embodiment, the image blur is corrected by moving the subgroup N1 constituting the intermediate group GP so as to have a component in the direction perpendicular to the optical axis. Specifically, in the first and third embodiments, the partial group N1 made up of the cemented lenses on the object side constituting the fourth lens unit L4 is moved so as to have a component in the direction perpendicular to the optical axis, whereby the optical The camera shake is corrected when the entire system vibrates (tilts). In Example 2, when the partial group N1 composed of the cemented lenses constituting the third lens group L3 is moved so as to have a component perpendicular to the optical axis, the entire optical system vibrates (tilts). The camera shake is corrected.

  In the aberration diagrams, Fno is the F number, and ω is the half angle of view (degrees), which is the angle of view based on the paraxial calculated value. In the spherical aberration diagram, the solid line d is the d line (wavelength 587.56 nm), and the two-dot chain line g is the g line (wavelength 435.8 nm). In the graph showing astigmatism, a solid line ΔS is a sagittal image plane at the d line, and a dotted line ΔM is a meridional image plane at the d line. The distortion aberration d is shown for the d line. In the chromatic aberration diagram of magnification, a two-dot chain line g is a g line. In the lateral aberration diagram, a solid line ΔM is a meridional ray, and a dotted line ΔS is a sagittal ray. In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens group is positioned at both ends of a range in which the zoom lens unit can move on the optical axis.

  The zoom lens of each embodiment is configured as follows in order from the object side to the image side in order to ensure a predetermined zoom ratio and correct various aberrations. A first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, an intermediate group GP having a positive refractive power as a whole, including one or more lens groups, a lens group NF having a negative refractive power, The lens unit PL has a positive refractive power.

  By disposing the lens unit NF having a negative refractive power on the image side of the intermediate group GP having a positive refractive power, an increase in the angle of view is achieved while suppressing an increase in the effective diameter of the front lens. Furthermore, the sensitivity of the image plane to tilt when the sub-group N1 having negative refractive power for image blur correction is decentered is reduced. By disposing the lens unit PL having a positive refractive power on the image side of the lens unit NF having a negative refractive power, the lens unit PL having a positive refractive power has a role of a field lens, and the exit pupil position is moved away from the lens unit PL. The image-side telecentric imaging necessary for a photographing apparatus using an image sensor or the like is achieved.

  During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves toward the object side. During zooming from the wide-angle end to the telephoto end, zooming is performed by increasing the distance between the first lens unit L1 and the second lens unit L2. The subsequent lens group is also moved so that the distance between the second lens group L2 and the intermediate group GP is narrowed, whereby the entrance pupil at the telephoto end is arbitrarily moved to reduce the size of the entire system.

  Further, during zooming, the variable power of the first lens unit L1 and the second lens unit L2 is shared by moving the intermediate group GP having positive refractive power as a whole including one or more lens units. Thereby, the amount of movement of the first lens unit L1 and the second lens unit L2 is reduced during zooming, and the total lens length at the telephoto end is shortened. The intermediate group GP has at least three components in order from the object side to the image side: a positive refractive power subgroup P1, a negative refractive power subgroup N1, and a positive refractive power subgroup P2. ing.

  The intermediate group GP plays a role of converging a strong divergent light beam emitted from the second lens unit L2 having a strong negative refractive power, and it is necessary to reduce an increase in the radial size of the subsequent lens. Further, by arranging at least three components, that is, a positive refractive power subgroup P1, a negative refractive power subgroup N1, and a positive refractive power subgroup P2, it is generated by the positive refractive action of the intermediate group GP. Various aberrations are reduced (corrected) by the negative refracting action. Further, by moving the lens unit N1 having the negative refractive power so as to have a component perpendicular to the optical axis, a large image position is corrected with a small amount of movement. That is, image blur correction is performed.

Note that image blur correction may be performed by moving an arbitrary lens group in a direction having a component perpendicular to the optical axis. In each embodiment, the lateral magnification of the sub-group N1 when focused to infinity at the wide-angle end is βnw, and the sub-group N1 when focused to infinity at the wide-angle end is arranged on the image side. The lateral magnification of the optical system is βlw. At this time,
−3.0 <(1-βnw) × βlw <−1.5 (1)
This satisfies the conditional expression Next, the technical meaning of the above conditional expression will be described.

Conditional expression (1) defines the image shift sensitivity at the time of image stabilization of the subgroup N1. Here, the image shift sensitivity TS means the shift amount ΔL in the vertical direction of the shift group when the shift group is moved in the direction perpendicular to the optical axis, and the image on the image plane at that time (imaging position). Of the amount of movement ΔI in the direction perpendicular to the optical axis of TS = ΔI / ΔL
It is.

When the upper limit of conditional expression (1) is exceeded, the amount of movement of the subgroup N1 necessary for shifting the image by a predetermined amount becomes large, and it becomes difficult to reduce the size of the entire system. In addition, aberration variation increases when the subgroup N1 is shifted in order to shift the image by a predetermined amount. When the lower limit of conditional expression (1) is exceeded, the image is greatly shifted with respect to the minute movement of the subgroup N1, and it is difficult to control the image shift with high accuracy. In each embodiment, the numerical range of conditional expression (1) is more preferably set as follows.
-2.40 <(1-βnfw) × βlw <−1.51 (1a)

By satisfying conditional expression (1a), the image shift sensitivity of the subgroup N1 at the wide-angle end is set appropriately, and the subgroup N1 for image stabilization can be easily downsized. More preferably, the numerical range of the conditional expression (1a) is set as follows.
−1.80 (1−βnfw) × βlw <−1.52 (1b)

  By satisfying the lens configuration and conditional expression (1) as described above, a small zoom lens with a high zoom ratio that achieves high imaging performance in the zoom region while reducing the size and weight of the subgroup N1 for image stabilization. can get.

  In each embodiment, it is more preferable to satisfy one or more of the following conditional expressions. The combined focal length of the intermediate group GP at the wide angle end is fAw, and the focal length of the subgroup N1 is fN1. Let fnf be the focal length of the lens group NF, and ft be the focal length of the entire system at the telephoto end. The focal length of the second lens unit L2 is f2, and the focal length of the entire system at the wide angle end is fw. Let fP2 be the focal length of the subgroup P2. Let the focal length of the lens group PL be fpL. The subgroup N1 is composed of one positive lens N1p and one negative lens N1n. The Abbe number of the material of the positive lens N1p is νn1p, and the Abbe number of the material of the negative lens N1n is νn1n. The subgroup P2 includes a single positive lens P2p, and the Abbe number of the material of the positive lens P2p is νP2p.

At this time, one or more of the following conditional expressions should be satisfied.
0.6 <| fN1 / fAw | <2.0 (2)
0.15 <| fnf / ft | <0.75 (3)
0.6 <| f2 / fw | <1.4 (4)
0.5 <| fN1 / fP2 | <0.9 (5)
0.25 <| fnf / fpL | <0.95 (6)
1.5 <νn1n / νn1p <3.2 (7)
50.0 <νP2p <95.0 (8)

Note that the Abbe number νd of the material is Nd, NF, and NC when the refractive indexes of the Fraunhofer wire d-line, F-line, and C-line are
νd = (Nd−1) / (NF−NC)
Defined by

  Conditional expression (2) defines the focal length fN1 of the negative refractive power subgroup N1 by the combined focal length fAw of the positive refractive power intermediate group GP at the wide angle end. The image stabilization subgroup N1 has an appropriate image shift sensitivity and reduces the imaging performance during image stabilization. When the negative refractive power of the subgroup N1 becomes weaker than the upper limit of the conditional expression (2) (when the absolute value of the negative refractive power becomes small), the image shift sensitivity of the subgroup N1 becomes small. As a result, in order to obtain a sufficient anti-vibration effect, the amount of movement of the subgroup N1 must be increased, the outer diameter of the anti-vibration unit is increased, the amount of peripheral light during vibration reduction is reduced, and the single stop is reduced. It tends to increase.

  If the negative refractive power of the subgroup N1 is increased beyond the lower limit of the conditional expression (2), a sufficient antivibration effect can be obtained even if the movement amount of the subgroup N1 is small. However, at the time of image stabilization, the occurrence of decentered coma increases, and the correction of the inclination of the field curvature is insufficient, so that the imaging performance at the time of image stabilization is deteriorated.

  Conditional expression (3) defines the ratio between the focal length fnf of the lens unit NF having a negative refractive power and the focal length ft of the entire system at the telephoto end. If the upper limit of conditional expression (3) is exceeded and the negative refractive power of the lens group NF becomes weaker, the zooming action of the lens group NF becomes smaller, and the entire system becomes larger when trying to obtain a predetermined zoom ratio. . In addition, when the angle of view is widened, the effective diameter of the front lens increases. If the negative refractive power of the lens unit NF is increased beyond the lower limit of the conditional expression (3), the total lens length is shortened, but astigmatism increases from the intermediate focal length range to the telephoto end. It becomes difficult to correct aberrations. In addition, the fluctuation of distortion increases during zooming.

  Conditional expression (4) defines the ratio between the focal length f2 of the second lens unit L2 and the focal length fw of the entire system at the wide-angle end. If the upper limit of conditional expression (4) is exceeded and the negative refractive power of the second lens unit L2 becomes weak, it is necessary to increase the total lens length in order to achieve a high zoom ratio, which is not preferable. If the negative refractive power of the second lens unit L2 is increased beyond the lower limit of the conditional expression (4), it is easy to increase the zoom ratio and shorten the total lens length, but the Petzval sum increases in the negative direction, and the image Surface curvature increases.

  Conditional expression (5) defines the ratio of the focal lengths of the negative refractive power subgroup N1 and the positive refractive power subgroup P2. Conditional expression (5) is for reducing the decentration coma aberration and the inclination of the field curvature during image stabilization. If the upper limit of conditional expression (5) is exceeded, the converging action of the subgroup P2 becomes too strong, and the manufacturing error sensitivity due to the eccentricity of the entire intermediate group GP with positive refractive power increases, and the optical performance during manufacturing is good. Difficult to maintain. If the lower limit of conditional expression (5) is exceeded, the negative refractive power of the subgroup N1 becomes too strong, and it becomes difficult to correct decentration coma or chromatic aberration during image stabilization.

  Conditional expression (6) defines the ratio of the focal length of the lens unit NF having a negative refractive power and the focal length of the lens unit PL having a positive refractive power. Conditional expression (6) is for reducing the size of the entire system while achieving a high zoom ratio. When the positive refractive power of the lens unit PL increases beyond the upper limit of conditional expression (6), many aberrations occur from the wide-angle end to the telephoto end. In order to correct the various aberrations at this time, the lens unit PL This is not preferable because the number of lenses constituting the lens increases. Exceeding the lower limit of conditional expression (6) is not preferable because the exit pupil position becomes too close at the wide-angle end. In addition, variations in spherical aberration and axial chromatic aberration due to focusing increase.

  Conditional expression (7) defines the ratio of the Abbe number of the material of one positive lens N1p and the Abbe number of the material of one negative lens N1n constituting the negative refractive power subgroup N1. When the ratio of the Abbe number increases beyond the upper limit of conditional expression (7), it becomes difficult to correct fluctuations in coma during focusing while correcting fluctuations in color shift during image stabilization in a well-balanced manner. When the Abbe number ratio is reduced beyond the lower limit of conditional expression (7), the power of the lens surfaces of the lenses constituting the subgroup N1 increases due to achromaticity in the subgroup N1, and low-order aberration coefficients Becomes larger, and it becomes difficult to correct various aberrations.

  Conditional expression (8) defines the Abbe number of the material of the positive lens P2p constituting the subgroup P2 having a positive refractive power. Conditional expression (8) is for reducing the eccentric chromatic aberration that occurs during image stabilization. If it is within the numerical range of the conditional expression (8), it is easy to ensure image shift sensitivity at the time of image stabilization of the subgroup N1, and it becomes easy to shorten the total lens length at the wide angle end.

More preferably, the numerical ranges of the conditional expressions (2) to (8) are set as follows.
0.7 <| fN1 / fAw | <1.5 (2a)
0.20 <| fnf / ft | <0.65 (3a)
0.8 <| f2 / fw | <1.2 (4a)
0.60 <| fN1 / fP2 | <0.85 (5a)
0.3 <| fnf / fpL | <0.9 (6a)
1.55 <νn1n / νn1p <3.00 (7a)
51.0 <νP2p <95.0 (8a)

  By satisfying the conditional expression (2a), it is preferable that the image stabilizing lens group can suppress a change in image forming performance during image stabilization while ensuring appropriate image shift sensitivity. By satisfying conditional expression (3a), it is possible to achieve a reduction in the total lens length at the wide angle end and a reduction in the effective diameter of the front lens while optimizing the variable magnification sharing of the lens unit NF having a negative refractive power. By satisfying conditional expression (4a), the Petzval sum can be set appropriately while achieving a wide angle of view and a high zoom ratio. By satisfying the conditional expression (5a), it is easy to reduce the size and weight of the lens unit N1 having negative refractive power while suppressing variations in spherical aberration due to zooming. By satisfying the conditional expression (6a), it becomes easy to satisfactorily correct the fluctuation of the field curvature accompanying the focusing over the entire zoom range.

More preferably, the numerical ranges of the conditional expressions (2a) to (8a) are set as follows.
0.81 <| fN1 / fAw | <1.10 (2b)
0.25 <| fnf / ft | <0.55 (3b)
0.90 <| f2 / fw | <0.98 (4b)
0.70 <| fN1 / fP2 | <0.78 (5b)
0.38 <| fnf / fpL | <0.85 (6b)
1.60 <νn1n / νn1p <2.50 (7b)
52.0 <νP2p <95.0 (8b)

  In each embodiment, the above-described configuration achieves a high zoom ratio while shortening the total lens length at the telephoto end at the wide-angle end. In Examples 1 to 3, an aspherical lens is used for the second lens unit L2, and the field curvature and distortion are corrected well at the wide-angle end. In Examples 1 to 3, an aspheric lens is used for the intermediate group GP, and spherical aberration and coma are corrected well.

  Next, an embodiment of a digital still camera using the zoom lens of the present invention as an imaging optical system will be described with reference to FIG. In FIG. 10, reference numeral 10 denotes a camera body, and 11 denotes a photographing optical system constituted by any of the zoom lenses described in the first to third embodiments. Reference numeral 12 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 11 and is built in the camera body.

  Hereinafter, specific numerical data corresponding to Examples 1 to 3 will be described. In each numerical data, i indicates a surface number counted from the object side. ri is the radius of curvature of the i-th optical surface (i-th surface). di is the axial distance between the i-th surface and the (i + 1) -th surface. ndi and νdi are the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively. The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, K is the conic constant, and A4, A6, A8, and A10 are non- Spherical coefficient

It is expressed by the following formula. * Means a surface having an aspherical shape. “E-x” means 10 ^−x . BF is a back focus and indicates a distance from the final lens surface to the image plane. The total lens length is a value obtained by adding the back focus distance to the distance from the first lens surface to the final lens surface. The wide angle indicates the wide angle end, the middle indicates the intermediate zoom position, and the telephoto indicates the telephoto end. Table 1 shows the relationship between the parameters relating to the above-described conditional expressions and the numerical examples for the conditional expressions.

[Example 1]
Unit mm

Surface data surface number rd nd νd
1 200.000 2.00 1.90366 31.3
2 117.258 4.84 1.59522 67.7
3 -1996.572 0.10
4 59.253 3.40 1.80 400 46.6
5 94.068 (variable)
6 * 122.804 1.20 1.85135 40.1
7 17.681 9.99
8 -59.503 1.10 1.80 400 46.6
9 50.979 0.15
10 30.400 6.41 1.85478 24.8
11 -85.386 1.04
12 -46.699 1.10 1.85135 40.1
13 * -101.812 (variable)
14 (Aperture) ∞ 1.00
15 * 24.580 5.60 1.68893 31.1
16 * -79.952 2.00
17 54.197 2.80 1.59522 67.7
18 -99.071 1.20 1.92286 20.9
19 19.849 0.70
20 23.371 4.45 1.53775 74.7
21 -25.804 (variable)
22 -43.083 2.35 1.84666 23.8
23 -15.396 1.00 1.74400 44.8
24 32.508 2.50
25 49.686 2.39 1.75 500 52.3
26 -70.439 (variable)
27 -81.527 3.04 2.00272 19.3
28 -17.514 1.00 1.90 200 25.1
29 * 52.842 (variable)
30 131.092 5.66 1.76802 49.2
31 -82.826 (variable)
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 5.52866e-006 A 6 = -1.44612e-009 A 8 = -9.34795e-013 A10 = 1.61333e-015

Side 13
K = -7.71052e + 000 A 4 = 4.58477e-006 A 6 = 7.92379e-009 A 8 = -1.01350e-012 A10 = -3.66982e-014

15th page
K = -6.44296e-001 A 4 = -1.25759e-006 A 6 = 1.16607e-008 A 8 = 1.84096e-011

16th page
K = -1.60228e + 001 A 4 = 9.67912e-006 A 6 = 1.00289e-008 A 8 = 1.79731e-011

29th page
K = -1.39034e + 001 A 4 = 1.51478e-005 A 6 = -1.61955e-008

Various data Zoom ratio 4.76
Wide angle Medium Telephoto focal length 24.70 47.76 117.49
F number 4.12 4.80 5.80
Half angle of view (degrees) 41.22 24.37 10.43
Image height 21.64 21.64 21.64
Total lens length 155.71 163.55 207.88
BF 37.45 39.88 43.95

d 5 1.50 19.64 52.92
d13 40.38 17.57 2.03
d21 1.45 3.61 9.80
d26 1.95 6.32 1.89
d29 5.98 9.52 30.28
d31 37.45 39.88 43.95

Zoom lens group data group Start surface Focal length
1 1 134.87
2 6 -24.04
3 14 25.77
4 22 -141.89
5 27 -41.86
6 30 66.86

[Example 2]
Unit mm

Surface data surface number rd nd νd
1 198.084 2.00 1.90366 31.3
2 85.429 8.33 1.59522 67.7
3 -303.127 0.10
4 60.312 3.43 1.77250 49.6
5 88.518 (variable)
6 * -707.071 1.37 1.85135 40.1
7 20.223 7.32
8 -88.936 1.10 1.80400 46.6
9 58.654 0.14
10 45.291 6.46 1.85478 24.8
11 -64.599 1.04
12 -41.559 1.10 1.85135 40.1
13 * -63.626 (variable)
14 (Aperture) ∞ 1.00
15 * 18.505 7.14 1.61881 63.9
16 * -70.898 1.80
17 99.888 3.59 1.61772 49.8
18 -33.355 1.20 1.83400 37.2
19 16.917 1.34
20 29.878 4.14 1.69680 55.5
21 -31.711 1.43
22 -74.980 2.35 1.85478 24.8
23 -24.236 1.00 1.76200 40.1
24 33.340 1.50
25 22.696 3.31 1.43875 94.9
26 -95.810 (variable)
27 9093.979 1.69 1.92286 18.9
28 -57.579 1.00 1.90270 31.0
29 * 33.168 (variable)
30 -70.118 3.85 1.53775 74.7
31 -29.878 (variable)
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 1.35238e-006 A 6 = -2.11920e-009 A 8 = -3.56777e-012 A10 = 2.50711e-015

Side 13
K = -1.07455e + 001 A 4 = -9.37632e-006 A 6 = 4.77088e-009 A 8 = -2.39009e-011 A10 = -6.00690e-015

15th page
K = -1.19690e + 000 A 4 = 1.48889e-005 A 6 = 2.00152e-008 A 8 = 6.89335e-011

16th page
K = -2.99345e + 001 A 4 = 8.00475e-006 A 6 = 1.34720e-008 A 8 = -4.95292e-011

29th page
K = -7.70841e-001 A 4 = 7.70697e-006 A 6 = -1.57622e-008

Various data Zoom ratio 4.66
Wide angle Medium Tele focal length 28.80 49.50 134.07
F number 4.12 5.00 5.88
Half angle of view (degrees) 36.91 23.61 9.17
Image height 21.64 21.64 21.64
Total lens length 160.29 164.94 220.08
BF 36.29 40.30 52.70

d 5 4.80 12.69 54.72
d13 43.89 23.82 7.71
d26 1.31 5.49 7.99
d29 5.28 13.93 28.25
d31 36.29 40.30 52.70

Zoom lens group data group Start surface Focal length
1 1 138.57
2 6 -26.01
3 14 31.16
4 27 -37.38
5 30 93.68

[Example 3]
Unit mm

Surface data surface number rd nd νd
1 200.000 2.00 1.90366 31.3
2 94.927 6.35 1.59522 67.7
3 -4261.543 0.10
4 57.253 4.60 1.80 400 46.6
5 112.090 (variable)
6 * 495.416 1.40 1.80139 45.5
7 17.478 9.19
8 283.855 1.20 1.83481 42.7
9 18.642 0.00 1.83481 42.7
10 18.642 9.27 1.85478 24.8
11 -367.149 2.48
12 -32.790 1.30 1.80610 40.7
13 * -44.021 (variable)
14 (Aperture) ∞ 1.00
15 * 27.380 7.13 1.68893 31.1
16 * -71.562 2.00
17 53.342 2.74 1.59522 67.7
18 -79.580 1.20 1.92286 20.9
19 21.550 0.70
20 24.707 6.13 1.53775 74.7
21 -29.257 (variable)
22 -44.628 4.48 1.84666 23.8
23 -16.462 1.00 1.74400 44.8
24 34.942 2.50
25 53.785 3.18 1.75 500 52.3
26 -65.207 (variable)
27 -140.161 4.24 2.00272 19.3
28 -21.678 1.00 1.90 200 25.1
29 * 58.838 (variable)
30 132.144 6.05 1.76802 49.2
31 -82.826 (variable)
Image plane ∞

Aspheric data 6th surface
K = 0.00000e + 000 A 4 = 7.76486e-006 A 6 = -1.25167e-008 A 8 = 1.48000e-011 A10 = -1.00877e-014

Side 13
K = 4.90182e + 000 A 4 = 2.75620e-006 A 6 = 2.02433e-009 A 8 = 2.98711e-011 A10 = 2.12796e-014

15th page
K = -1.36975e + 000 A 4 = 4.56482e-006 A 6 = 5.46033e-009 A 8 = 7.10109e-011

16th page
K = -7.21493e + 000 A 4 = 1.00367e-005 A 6 = -4.93544e-010 A 8 = 6.35866e-011

29th page
K = -1.05191e + 001 A 4 = 9.63246e-006 A 6 = -7.49993e-009

Various data Zoom ratio 4.15
Wide angle Medium Telephoto focal length 24.70 37.26 102.44
F number 4.12 4.12 4.12
Half angle of view (degrees) 41.22 30.14 11.93
Image height 21.64 21.64 21.64
Total lens length 160.72 164.12 206.41
BF 35.75 35.55 36.95

d 5 1.50 11.23 43.41
d13 32.94 19.08 1.97
d21 1.33 3.42 10.77
d26 1.65 5.54 1.78
d29 6.30 8.06 30.29
d31 35.75 35.55 36.95

Zoom lens group data group Start surface Focal length
1 1 117.58
2 6 -22.50
3 14 27.85
4 22 -189.91
5 27 -55.49
6 30 67.11

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group GP Lens group with positive refractive power NF Lens group PL with negative refractive power Positive refraction Power lens group

Claims (10)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, and an intermediate group having a positive refractive power as a whole, including one or more lens groups, arranged in order from the object side to the image side, negative In a zoom lens which is composed of a lens unit NF having a refractive power of λ and a lens unit PL having a positive refractive power, and the interval between adjacent lens units changes during zooming,
The intermediate group is arranged in order from the object side to the image side, and moves in a direction having a component in a direction perpendicular to the optical axis when correcting image blur, and having a positive refractive power subgroup P1 that does not move during image blur correction. It consists of a negative refractive power subgroup N1 and a positive refractive power subgroup P2 that does not move for image blur correction.
The partial group N1 includes one positive lens N1p and one negative lens N1n.
During zooming, the focal lengths of the subgroup N1 and the subgroup P2 do not change,
The lateral magnification of the partial group N1 when focused at infinity at the wide angle end is βnw, and the lateral magnification of the optical system arranged on the image side from the partial group N1 when focused at infinity at the wide angle end When the magnification is βlw, the focal length of the subgroup P2 is fP2, the focal length of the subgroup N1 is fN1, the Abbe number of the material of the positive lens N1p is νn1p, and the Abbe number of the material of the negative lens N1n is νn1n. ,
−3.0 <(1−βnw) × βlw <−1.5
0.5 <| fN1 / fP2 | <0.9
1.5 <νn1n / νn1p <3.2
A zoom lens characterized by satisfying the following conditional expression: When the combined focal length of the intermediate group at the wide angle end is fAw and the focal length of the subgroup N1 is fN1,
0.6 <| fN1 / fAw | <2.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the lens group NF is fnf and the focal length of the entire system at the telephoto end is ft,
0.15 <| fnf / ft | <0.75
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the second lens group is f2, and the focal length of the entire system at the wide angle end is fw,
0.6 <| f2 / fw | <1.4
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the lens group NF is fnf and the focal length of the lens group PL is fpL,
0.25 <| fnf / fpL | <0.95
The zoom lens according to any one of claims 1 to 4, characterized by satisfying the following conditional expression. The partial group P2 includes one positive lens P2p, and when the Abbe number of the material of the positive lens P2p is νP2p,
50.0 <νP2p <95.0
The zoom lens according to any one of claims 1 to 5, characterized by satisfying the following conditional expression. The zoom lens according to any one of claims 1 to 6 , wherein the intermediate group includes a third lens group having a positive refractive power and a fourth lens group having a negative refractive power. 8. The zoom lens according to claim 7 , wherein the third lens group includes the partial group P1, and the fourth lens group includes the partial group N1 and the partial group P2. The zoom lens according to any one of claims 1 to 6 , wherein the intermediate group includes a third lens group having a positive refractive power. Imaging apparatus characterized by having an image pickup device which receives an image formed by the zoom lens and the zoom lens according to any one of claims 1 to 9.