JP6071473B2 - Zoom lens and imaging apparatus using the same - Google Patents

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is suitable as an image pickup optical system used for, for example, a digital still camera, a video camera, a film camera, a TV camera, and a surveillance camera.

  In recent years, an imaging optical system used in an imaging apparatus such as a digital still camera or a video camera using a solid-state imaging device is required to be a small zoom lens with a wide angle of view and a high zoom ratio. In addition, in this type of image pickup apparatus, various optical members such as a low-pass filter and a color correction filter are disposed between the rearmost lens portion and the image pickup element, so that the image pickup optical system used for the image pickup apparatus is required to have a long back focus. . As a zoom lens having a small overall system, a wide angle of view, and a high zoom ratio, a negative lead type zoom lens is known which is preceded by a lens unit having a negative refractive power (positioned closest to the object side).

  As a negative lead type zoom lens, in order from the object side to the image side, a three-group zoom including a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power The lens is known. In this three-group zoom lens, the first lens group is composed of a negative lens and a positive lens, the second lens group is composed of three or four lenses, and the third lens group is composed of one positive lens. A three-group zoom lens having a wide angle of view is known (Patent Documents 1 and 2).

  Patent Document 1 discloses a small three-group zoom lens having a shooting angle of view of 53.7 ° at the wide-angle end and a zoom ratio of about 2.8. Patent Document 2 discloses a small zoom lens having a shooting angle of view of 30 to 35 degrees at the wide-angle end and a zoom ratio of about 2.8 to 3.8. In recent years, in an imaging apparatus, distortion of the various aberrations is not optically corrected, and an image obtained from the imaging element is electrically corrected by image processing to obtain a high-quality image. Yes.

JP-A-10-170826 JP 2010-85875 A

  In recent years, there has been a strong demand for a zoom lens used in an imaging apparatus that is small in size, has a wide angle of view, and a high zoom ratio. In order to reduce the overall system size and increase the zoom ratio in the negative lead type three-group zoom lens described above, the lens configuration of each lens group constituting the zoom lens, the imaging magnification of each lens group, etc. are set appropriately. It becomes important to do. For example, it is possible to appropriately set the configuration of the first lens group that corrects the image plane variation accompanying zooming, the imaging magnification at the wide angle end of the second lens unit for zooming, the configuration of the third lens group, and the like. is important.

  If these structures are inappropriate, it becomes very difficult to obtain high optical performance while reducing the size of the entire system, widening the angle of view, and increasing the zoom ratio.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens having a compact lens system as a whole, a high zoom ratio, and high optical performance over the entire zoom range, and an image pickup apparatus having the zoom lens.

The zoom lens according to the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. In zoom lenses in which the distance between adjacent lens groups changes during zooming,
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, The radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21 , and the distance on the optical axis from the most object-side lens surface to the most image-side lens surface of the first lens group is D1, When the distance on the optical axis between the image side lens surface of the negative lens included in the first lens group and the object side lens surface of the positive lens included in the first lens group is d12 ,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
0.56 ≦ d12 / D1 <0.7
It satisfies the following conditional expression.
In addition, the zoom lens of the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. In the zoom lens in which the interval between adjacent lens groups changes during zooming,
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The second lens group is composed of a positive lens and a cemented lens in which a positive lens and a negative lens are disposed in order from the object side to the image side.
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, When the radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
It satisfies the following conditional expression.
In addition, the zoom lens of the present invention includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side. In the zoom lens in which the interval between adjacent lens groups changes during zooming,
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The second lens group includes a positive lens, a cemented lens in which a positive lens and a negative lens are cemented, and a positive lens, which are arranged in order from the object side to the image side.
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, When the radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens in which the entire lens system is compact, the zoom ratio is high, and high optical performance is obtained in the entire zoom range.

Lens sectional view of Numerical Example 1 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end according to Numerical Example 1 of the present invention. Lens sectional view of Numerical Example 2 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end according to Numerical Example 2 of the present invention. Lens sectional view of Numerical Example 3 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, at the intermediate zoom position, and at the telephoto end according to Numerical Example 3 of the present invention. Lens sectional view of Numerical Example 4 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end according to Numerical Example 4 of the present invention. Lens sectional view of Numerical Example 5 of the present invention (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end according to Numerical Example 5 of the present invention. Schematic diagram of 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, disposed in order from the object side to the image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power ing. During zooming, the interval between adjacent lens groups changes.

  Specifically, during zooming from the wide-angle end to the telephoto end to the zoom position, the first lens unit L1 moves along a locus convex toward the image side to correct image plane fluctuations accompanying zooming. Yes. The second lens unit L2 moves monotonously to the object side to perform main magnification. The third lens unit L3 moves along a locus convex toward the image side.

  FIG. 1 is a lens cross-sectional view at the wide-angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention. 2A, 2B, and 2C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end) of the zoom lens of Example 1, respectively. Embodiment 1 is a zoom lens having a zoom ratio of 3.81 and an aperture ratio (F number) of about 2.82 to 6.05.

  FIG. 3 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 4A, 4B, and 4C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the second exemplary embodiment. The second embodiment is a zoom lens having a zoom ratio of 3.81 and an aperture ratio of about 2.83 to 5.98.

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. 6A, 6B, and 6C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the third exemplary embodiment. Example 3 is a zoom lens having a zoom ratio of 4.12 and an aperture ratio of about 2.70 to 5.98.

  FIG. 7 is a lens cross-sectional view at the wide-angle end of the zoom lens according to a fourth exemplary embodiment of the present invention. 8A, 8B, and 8C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively, of the zoom lens according to the fourth exemplary embodiment. The fourth exemplary embodiment is a zoom lens having a zoom ratio of 4.00 and an aperture ratio of about 2.79 to 5.98.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. 10A, 10B, and 10C are aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 5, respectively. The fifth exemplary embodiment is a zoom lens having a zoom ratio of 3.88 and an aperture ratio of about 3.03 to 6.60. FIG. 11 is a schematic diagram of a main part of a digital still camera (image pickup apparatus) including the zoom lens of the present invention. 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, L1 is a first lens group having negative refractive power (optical power = reciprocal of focal length), L2 is a second lens group having positive refractive power, and L3 is a third lens group having positive refractive power. It is. SP is an F-number determining member (hereinafter referred to as “aperture stop”) that functions as an aperture stop that determines (limits) an open F-number (Fno) light beam. GB is an optical block corresponding to an optical filter, a face plate, a crystal low-pass filter, an infrared cut filter, or the like.

  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 photosensitive surface corresponding to the film surface is provided. Among the aberration diagrams, in the spherical aberration diagram, the solid line is the d line and the two-dot chain line is the F line. In the astigmatism diagram, ΔM and ΔS represent a meridional image surface and a sagittal image surface, respectively. The lateral chromatic aberration is represented by the g line. Fno is an F number, and ω is a half angle of view (degrees).

  In each of the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit (second lens unit L2) is positioned at both ends of the range in which it can move on the optical axis due to the mechanism. In the lens cross-sectional view, arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end.

  In the zoom lens of each embodiment, when zooming from the wide-angle end to the telephoto end zoom position, the first lens unit L1 moves along a locus that is convex toward the image side, and corrects the image plane variation due to zooming. doing. The second lens unit L2 moves monotonously to the object side to perform main magnification. The third lens unit L3 moves along a locus convex toward the image side.

  Further, a rear focus type is employed in which the third lens unit L3 is moved on the optical axis to perform focusing. A solid line curve 3a and a dotted line curve 3b relating to the third lens unit L3 are movement trajectories for correcting image plane fluctuations caused by zooming when focusing on an object at infinity and an object at close distance, respectively. Further, when focusing from an infinitely distant object to a close object at the telephoto end, the third lens unit L3 is moved forward as indicated by an arrow 3c. Although the first lens unit L1 does not move in the optical axis direction for focusing, it may be moved as necessary for aberration correction.

Further, at the time of image blur correction, the whole or part of the second lens unit L2 moves in a direction having a component perpendicular to the optical axis. That is, image blurring that occurs when the zoom lens vibrates is corrected.

  The zoom lens of the present invention is characterized in that the entire system is compact while having a wide angle of view and a high zoom ratio. 2. Description of the Related Art Conventionally, there is a positive lead type four-group zoom lens composed of lens groups having positive, negative, positive, and positive refractive power in order from the object side to the image side. Compared with this four-group zoom lens, the negative lead type three-group zoom lens composed of lens groups having negative, positive, and positive refractive powers in order from the object side to the image side has a smaller number of constituting lenses, and therefore the entire system. Suitable for downsizing. In addition, the above-described negative lead type three-group zoom lens is also advantageous for widening the angle of view because it can capture a wide range of light rays with a small front lens effective diameter.

  On the other hand, when the zoom lens has a wide angle of view, various aberrations such as field curvature and distortion increase at the wide-angle end. Among these, if a method of allowing the generation of distortion and electrically correcting the distortion is taken, it is easy to effectively correct curvature of field effectively by setting the shape of the first lens group appropriately. become. Specifically, when the refractive power of each lens in the first lens unit L1 is increased in order to make the entire system compact, the curvature of the lens surface on the object side in the air lens in the first lens unit L1 is particularly tight. (The radius of curvature becomes smaller). In each of the embodiments, the curvature of the lens surface is relaxed at this time to reduce the deterioration of the curvature of the outermost field.

  Further, by appropriately setting the power arrangement in the first lens unit L1, the field curvature at the wide-angle end and the spherical aberration at the telephoto end, and the coma aberration at the intermediate zoom position are corrected well. Specifically, negative distortion is allowed to occur by relaxing the power of the positive lens in the first lens unit L1, and various aberrations are observed on the telephoto side when the field curvature and the zoom ratio are increased at the wide angle end. The occurrence is reduced. Satisfying these two conditions makes it easy to correct various aberrations satisfactorily while allowing distortion at the wide-angle end.

The zoom lens of the present invention has a wide angle of view, corresponds to a high zoom ratio (for example, a zoom ratio of about 4), and has the following configuration in order to make the entire system compact. The first lens unit L1 includes a negative lens and a positive lens arranged in order from the object side to the image side. The focal length of the positive lens included in the first lens unit L1 is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image-side lens surface of the negative lens included in the first lens unit L1 is r12, Let r21 be the radius of curvature of the object-side lens surface of the positive lens included in one lens unit L1.

At this time,
4.6 <f1p / fw <9.0 (1)
−0.08 <(r12−r21) / (r12 + r21) <− 0.01 (2)
The following conditional expression is satisfied.

  In order to achieve a wide angle of view while reducing the size of the entire system, it is important to appropriately set the lens configuration of the first lens unit L1 in which light rays pass through the periphery of the lens at the wide-angle end. In particular, the lens shape and power arrangement in the first lens unit L1 are important for correcting the change in field curvature due to the angle of view when the angle of view is widened.

  Conditional expression (1) relates to the power of the positive lens in the first lens unit L1. Conditional expression (1) is for satisfactorily correcting spherical aberration and axial chromatic aberration, particularly at the telephoto end. If the lower limit value of conditional expression (1) is not reached, the power of the positive lens becomes stronger and correction of distortion becomes easy, but it becomes difficult to correct spherical aberration at the telephoto end. Further, it is difficult to correct axial chromatic aberration at the telephoto end and lateral chromatic aberration at the wide-angle end in a balanced manner.

  On the other hand, if the upper limit of conditional expression (1) is exceeded, the power of the positive lens is weakened, and correction of spherical aberration becomes easy at the telephoto end, but the power of the negative lens in the first lens unit L1 also needs to be weakened. Therefore, it is difficult to correct longitudinal chromatic aberration at the telephoto end. Further, in order to correct lateral chromatic aberration at the wide-angle end, it is necessary to widen the distance between the negative lens and the positive lens in the first lens unit L1, and the entire system becomes large.

  Conditional expression (2) relates to the shape of the air lens formed by the negative lens and the positive lens of the first lens unit L1. Conditional expression (2) is for satisfactorily correcting curvature of field and distortion at the wide-angle end. If the lower limit value of conditional expression (2) is not reached, the curvature of the lens surface on the object side of the air lens becomes tight (the radius of curvature becomes small), and it becomes difficult to correct curvature of field at the wide angle end. On the other hand, if the upper limit value of conditional expression (2) is exceeded, the curvature of the lens surface on the object side of the air lens becomes loose (the radius of curvature becomes large), and the correction of distortion becomes easy, but the first lens unit L1. The power of the lens becomes weaker, and the total lens length and effective diameter of the front lens increase.

  As described above, according to each embodiment, it is possible to obtain a zoom lens having high optical performance in which field curvature is well corrected over the entire zoom region while reducing the size of the entire system and increasing the zoom ratio.

In each embodiment, it is more preferable to satisfy one or more of the following conditions. The third lens unit L3 is composed of one positive lens and the object side lens surface of the positive lens of the third lens unit L3, and the radius of curvature of each r31, r32 of the lens surface on the image side.

Let the focal length of the third lens unit L3 be f3. The distance on the optical axis from the most object side lens surface of the first lens unit L1 to the most image side lens surface is D1, and the image side lens surface and the first lens unit of the negative lens included in the first lens unit L1. Let d12 be the distance on the optical axis of the object-side lens surface of the positive lens included in L1. The lateral magnification at the wide-angle end of the second lens unit L2 is β2w. The Abbe number of the material of the positive lens included in the first lens unit L1 is ν1p. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.40 <(r31−r32) / (r31 + r32) <0.95 (3)
3.5 <f3 / fw <7.0 (4)
0.5 <d12 / D1 <0.7 (5)
−0.58 <β2w <−0.30 (6)
ν1p <20 (7)
Next, the technical meaning of each conditional expression described above will be described.

  In each embodiment, focusing is performed by the third lens unit L3. Conditional expression (3) relates to the lens shape of the positive lens of the third lens unit L3. Conditional expression (3) is for reducing the change in optical performance during focusing. If the lower limit value of conditional expression (3) is not reached, the convex meniscus shape of the lens surface on the image side becomes stronger, and the fluctuation of the field curvature increases during focusing from an object at infinity to a close object at the telephoto end.

  On the other hand, when the upper limit value of conditional expression (3) is exceeded, the positive lens approaches a biconvex shape, and fluctuations in field curvature during focusing are reduced at the telephoto end, but fluctuations in field curvature during focusing at the wide angle end. Will increase.

  Conditional expression (4) relates to the power (refractive power) of the third lens unit L3. Conditional expression (4) is for reducing a change in curvature of field during focusing. If the lower limit value of conditional expression (4) is not reached, the power of the third lens unit L3 becomes stronger and the amount of movement during focusing becomes smaller, so that the entire system can be easily made compact. Correction becomes difficult. On the other hand, if the upper limit value of conditional expression (4) is exceeded, the power of the third lens unit L3 will be weakened, the amount of movement during focusing will increase, making it difficult to make the entire system compact, and the curvature of field during focusing will be difficult. Changes will increase.

  Conditional expression (5) relates to the air space between the negative lens and the positive lens of the first lens unit L1. Conditional expression (5) is for satisfactorily correcting spherical aberration at the telephoto end while reducing the size of the entire system. If the lower limit of conditional expression (5) is not reached, the air space between the negative lens and the positive lens in the first lens unit L1 is narrowed, so that the entire system can be made compact. In order to correct lateral chromatic aberration at the wide-angle end, the power of each lens must be increased, and it becomes difficult to correct spherical aberration at the telephoto end. On the other hand, if the upper limit value of conditional expression (5) is exceeded, the air space between the negative lens and the positive lens in the first lens unit L1 increases, making it difficult to make the entire system compact.

  Conditional expression (6) relates to the lateral magnification of the second lens unit L2. Conditional expression (6) is mainly for favorably correcting curvature of field. If the lower limit of conditional expression (6) is not reached, the amount of extension of the second lens unit L2 on the telephoto end side during zooming becomes large, and the total lens length increases. On the other hand, when the value exceeds the upper limit value, the first lens unit L1 extends a lot toward the object side at the wide-angle end side, so that the effective diameter of the front lens increases. In addition, the variation in field curvature increases during zooming.

  Conditional expression (7) relates to the material of the positive lens of the first lens unit L1. Conditional expression (7) is mainly for satisfactorily correcting lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end. Exceeding the upper limit of conditional expression (7) makes it difficult to satisfactorily correct lateral chromatic aberration at the wide-angle end and axial chromatic aberration at the telephoto end.

  In each numerical example, it is more preferable to set the numerical ranges of the conditional expressions (1) to (8) as follows in terms of aberration correction.

4.65 <f1p / fw <8.80 (1a)
−0.07 <(r12−r21) / (r12 + r21) <− 0.01 (2a)
0.45 <(r31-r32) / (r31 + r32) <0.90 (3a)
3.8 <f3 / fw <6.8 (4a)
0.51 <d12 / D1 <0.69 (5a)
−0.57 <β2w <−0.32 (6a)
ν1p <19 (7a)
More preferably, the numerical ranges of the conditional expressions (1a) to (8a) are set as follows.

4.7 <f1p / fw <8.6 (1b)
−0.07 <(r12−r21) / (r12 + r21) <− 0.02 (2b)
0.50 <(r31−r32) / (r31 + r32) <0.85 (3b)
4.0 <f3 / fw <6.5 (4b)
0.51 <d12 / D1 <0.68 (5b)
−0.56 <β2w <−0.34 (6b)
10 <ν1p <19 (7b)
Conditional expression (5) is based on the numerical value of Example 2 shown in Table 1 described later.
0.56 ≦ d12 / D1 <0.7 (5x)
It is good to do.
In each numerical example, by configuring each lens group as described above, a zoom lens having a wide angle of view and a compact zoom lens corresponding to a zoom ratio of about 4 times can be obtained.

  Next, the lens configuration of each lens group will be described. The first lens unit L1 includes, in order from the object side to the image side, a negative meniscus lens having a convex object side surface and a meniscus positive lens having a convex object side surface. Both lenses have a spherical shape.

  In the zoom lens of each embodiment, the negative refractive power of the first lens unit L1 is increased in order to make the entire system small. That is, the absolute value of the negative refractive power is increased. At this time, many aberrations occur in the first lens unit L1. In particular, a lot of field curvature occurs at the wide-angle end. Therefore, the occurrence of various aberrations is reduced by increasing the air gap between the negative lens and the positive lens of the first lens unit L1 and relaxing the power (refractive power) of each lens. In addition, the use of a high refractive index material for the negative lens and the positive lens reduces the curvature of each lens surface, thereby reducing the occurrence of various aberrations.

The second lens unit L2 is disposed in order from the object side to the image side, and is a cemented lens in which a positive lens having a convex surface on the object side and an aspherical positive lens and a negative lens having a concave surface on the image side are cemented. These surfaces are convex and both lens surfaces are aspherical positive lenses. Or a positive lens with a convex surface on the object side, an aspherical positive lens, a cemented lens with a positive lens with a convex surface on the object side and a negative lens with a concave shape on the image side, or a convex surface on the object side Both lens surfaces are composed of aspherical positive lenses.

  In the zoom lens of each embodiment, the positive refractive power of the second lens unit L2 is increased in order to reduce the effective diameter of the first lens unit L1 while obtaining a wide angle of view at the wide angle end. That is, the absolute value of the positive refractive power is increased. At this time, many aberrations occur in the second lens unit L2. In particular, spherical aberration, coma, and field curvature frequently occur at the wide-angle end in the entire zoom range.

  In each embodiment, the generation of spherical aberration is reduced by using an aspherical positive lens having a material refractive index exceeding 1.8 on the most object side of the second lens unit L2. Further, the use of an aspherical positive lens closest to the image side reduces the occurrence of coma and field curvature. With such a lens configuration, the effective diameter of the front lens is reduced and high optical performance is obtained while widening the angle.

  The third lens unit L3 includes one positive lens having a concave shape on the object side. In the zoom lens according to each embodiment, the third lens unit L3 is configured with a small number of lenses to reduce the thickness and weight of the entire system. In particular, by making the object side concave and meniscus shaped, it is possible to obtain high optical performance over the entire screen by combining spherical aberration fluctuations that occur during focusing from an object at infinity to a close object at the wide-angle end together with fluctuations in field curvature. ing.

  Furthermore, the zoom lens proposed by the present invention may be used in combination with a system (imaging position) that corrects an electrical signal including distortion and lateral chromatic aberration by image processing. According to this, it becomes easy to obtain higher optical performance in the entire zoom region. The effective image circle diameter at the wide-angle end may be smaller than the effective image circle diameter at the telephoto end.

Next, an embodiment of a digital camera ( imaging device ) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG. In FIG. 11, reference numeral 20 denotes a digital camera body, 21 denotes a photographing optical system constituted by the zoom lens of the above-described embodiment, and 22 denotes an image pickup device such as a CCD that receives a subject image by the photographing optical system 21. Reference numeral 23 denotes recording means for recording a subject image received by the image sensor 22, and reference numeral 24 denotes a finder for observing the subject image displayed on a display element (not shown).

  The display element is constituted by a liquid crystal panel or the like, and a subject image formed on the image sensor 22 is displayed. The zoom lens of the present invention can also be applied to a mirrorless digital camera without a quick return mirror. Thus, by applying the zoom lens of the present invention to an imaging apparatus such as a digital camera, an imaging apparatus having a small size and high optical performance is realized.

  Next, numerical examples of the respective embodiments of the present invention will be shown. In each numerical example, i indicates the order of the surfaces from the object side.

  In numerical examples, ri is the radius of curvature of the i-th lens surface in order from the object side, di is the i-th lens thickness and air spacing in order from the object side, and ndi and νdi are the i-th lens in order from the object side. The refractive index and Abbe number for the d-line of the material. The four surfaces closest to the image side are filter members such as a crystal low-pass filter and an infrared cut filter. The back focus BF is indicated by an air-converted distance from the final lens surface to the image plane. 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 aspherical surfaces. As a coefficient

It is expressed by the following formula. [E + X] means [× 10 ^{+ x} ], and [eX] means [× 10 ^−x ]. An aspherical surface is indicated by adding * after the surface number.

  In each embodiment, the interval d5 is negative because it is counted from the object side to the image side in order from the aperture stop SP and the most object side lens of the second lens unit L2. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.

Numerical example 1
Surface data surface number rd nd νd
1 78.180 0.80 1.88300 40.8
2 6.510 1.71
3 7.133 0.78 1.95906 17.5
4 9.531 (variable)
5 ∞ -0.34
6 * 4.133 2.23 1.86400 40.6
7 11.473 0.50 1.80809 22.8
8 2.964 0.30
9 * 3.894 0.83 1.74330 49.3
10 * 12.022 (variable)
11 -147.051 1.10 1.77250 49.6
12 -15.764 (variable)
13 ∞ 0.30 1.51633 64.1
14 ∞ 0.70
15 ∞ 0.50 1.51633 64.1
16 ∞ 0.39
Image plane ∞

Aspheric data 6th surface
K = -1.81769e-001 A 4 = -1.12749e-004 A 6 = 2.37413e-005

9th page
K = -5.05375e-001 A 4 = 4.51443e-003 A 6 = 1.74164e-004 A 8 = 1.00075e-004

10th page
K = 2.40906e + 001 A 4 = 3.71651e-003 A 6 = 1.36437e-004 A 8 = 1.47248e-004 A10 = -4.27603e-006

Various data Zoom ratio 3.81

Focal length 5.15 12.40 19.60
F number 2.82 4.51 6.05
Half angle of view (degrees) 32.29 17.36 11.18
Total lens length 30.52 27.42 31.05
BF 4.68 3.56 4.18

d 4 13.97 4.26 1.28
d10 3.96 11.69 17.68
d12 3.06 1.94 2.56


Zoom lens group data group Start surface Focal length
1 1 -12.30
2 5 9.12
3 11 22.77
4 13 ∞

Numerical example 2
Surface data surface number rd nd νd
1 60.188 0.80 1.88300 40.8
2 6.495 1.98
3 7.036 0.73 1.95906 17.5
4 8.973 (variable)
5 (Aperture) ∞ -0.34
6 * 5.297 0.95 1.83613 42.8
7 13.941 0.20
8 4.629 1.22 1.57490 62.0
9 7.490 0.50 1.80809 22.8
10 2.861 0.63
11 * 5.026 0.75 1.76802 49.2
12 * 11.680 (variable)
13 -79.942 1.11 1.69680 55.5
14 -14.371 (variable)
15 ∞ 0.30 1.51633 64.1
16 ∞ 0.70
17 ∞ 0.50 1.51633 64.1
18 ∞ 0.39
Image plane ∞

Aspheric data 6th surface
K = -7.70586e-001 A 4 = 2.60274e-004 A 6 = 8.18122e-006

11th page
K = -5.08305e-001 A 4 = 4.87000e-003 A 6 = 1.01546e-004 A 8 = 1.28427e-004

12th page
K = 1.17165e + 001 A 4 = 3.73331e-003 A 6 = 2.17553e-005 A 8 = 1.50649e-004 A10 = 1.22259e-006

Various data Zoom ratio 3.81
Wide angle Medium telephoto focal length 5.15 12.45 19.60
F number 2.83 4.51 5.98
Half angle of view (degrees) 32.29 17.28 11.18
Total lens length 31.25 27.90 31.42
BF 4.68 3.26 4.12

d 4 14.30 4.36 1.29
d12 3.74 11.75 17.48
d14 3.06 1.63 2.50


Zoom lens group data group Start surface Focal length
1 1 -12.15
2 5 9.23
3 13 24.97
4 15 ∞

Numerical example 3
Surface data surface number rd nd νd
1 99.796 0.80 1.88300 40.8
2 6.657 2.10
3 7.274 0.75 2.10205 16.8
4 8.848 (variable)
5 ∞ -0.34
6 * 4.198 2.20 1.86400 40.6
7 10.479 0.50 1.80809 22.8
8 2.994 0.28
9 * 4.017 1.08 1.74330 49.3
10 * 14.822 (variable)
11 -90.614 1.31 1.65602 58.0
12 -14.383 (variable)
13 ∞ 0.30 1.51633 64.1
14 ∞ 0.70
15 ∞ 0.50 1.51633 64.1
16 ∞ 0.39
Image plane ∞

Aspheric data 6th surface
K = -2.38508e-001 A 4 = -1.39297e-004 A 6 = 2.23709e-005

9th page
K = -6.24090e-001 A 4 = 4.38804e-003 A 6 = 1.89934e-004 A 8 = 6.68400e-005

10th page
K = 3.64896e + 001 A 4 = 3.08308e-003 A 6 = 2.10578e-004 A 8 = 7.45452e-005 A10 = -7.81122e-007

Various data Zoom ratio 4.12
Wide angle Medium Telephoto focal length 4.75 12.29 19.60
F number 2.70 4.46 5.98
Half angle of view (degrees) 33.12 17.49 11.18
Total lens length 31.76 28.09 31.96
BF 4.67 3.03 4.09

d 4 14.85 4.30 1.28
d10 3.57 12.10 17.93
d12 3.05 1.41 2.47


Zoom lens group data group Start surface Focal length
1 1 -11.56
2 5 9.01
3 11 25.89
4 13 ∞

Numerical example 4
Surface data surface number rd nd νd
1 67.383 0.80 1.88300 40.8
2 6.407 2.33
3 6.797 0.76 2.10205 16.8
4 7.894 (variable)
5 ∞ -0.34
6 * 3.988 2.24 1.86400 40.6
7 12.813 0.50 1.80518 25.4
8 2.822 0.32
9 * 3.817 1.05 1.59201 67.0
10 * 40.180 (variable)
11 -47.476 1.34 1.56384 60.7
12 -12.398 (variable)
13 ∞ 0.30 1.51633 64.1
14 ∞ 0.70
15 ∞ 0.50 1.51633 64.1
16 ∞ 0.39
Image plane ∞

Aspheric data 6th surface
K = -2.53873e-001 A 4 = -1.53211e-004 A 6 = 1.84720e-005

9th page
K = 3.46060e-001 A 4 = 2.05396e-003 A 6 = 1.89513e-004 A 8 = 1.14561e-004

10th page
K = 2.79282e + 002 A 4 = 3.43106e-003 A 6 = 3.38359e-004 A 8 = 1.55660e-004 A10 = 2.57003e-006

Various data Zoom ratio 4.00
Wide angle Medium Telephoto focal length 4.55 11.53 18.22
F number 2.79 4.53 5.98
Half angle of view (degrees) 34.26 18.57 12.01
Total lens length 31.38 27.34 30.55
BF 4.68 2.72 4.09

d 4 14.61 4.32 1.28
d10 3.09 11.30 16.18
d12 3.06 1.10 2.47


Zoom lens group data group Start surface Focal length
1 1 -11.02
2 5 8.70
3 11 29.35
4 13 ∞

Numerical Example 5
Surface data surface number rd nd νd
1 67.588 0.80 1.88300 40.8
2 7.202 1.98
3 7.920 0.86 1.95906 17.5
4 10.420 (variable)
5 ∞ -0.34
6 * 4.127 1.89 1.86400 40.6
7 8.361 0.50 1.80809 22.8
8 2.998 0.29
9 * 4.201 0.86 1.74330 49.3
10 * 12.525 (variable)
11 -399.510 1.02 1.75500 52.3
12 -18.652 (variable)
13 ∞ 0.30 1.51633 64.1
14 ∞ 0.70
15 ∞ 0.50 1.51633 64.1
16 ∞ 0.40
Image plane ∞

Aspheric data 6th surface
K = -9.08659e-002 A 4 = -3.08749e-004 A 6 = 1.77505e-005

9th page
K = -4.23334e-001 A 4 = 4.44311e-003 A 6 = 2.05338e-004 A 8 = 4.54727e-005

10th page
K = 9.80376e + 000 A 4 = 4.08661e-003 A 6 = 3.23992e-004 A 8 = 5.28840e-005 A10 = 1.58454e-006

Various data Zoom ratio 3.88
Wide angle Medium Telephoto focal length 6.08 14.81 23.60
F number 3.03 4.86 6.60
Half angle of view (degrees) 29.85 14.66 9.32
Total lens length 34.09 30.82 35.40
BF 4.67 3.59 3.81

d 4 15.45 4.44 1.28
d10 6.11 14.93 22.45
d12 3.05 1.96 2.19


Zoom lens group data group Start surface Focal length
1 1 -13.85
2 5 10.35
3 11 25.89
4 13 ∞

L1 First lens group L2 Second lens group L3 Third lens group

Claims (11)

A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side, and are adjacent to each other during zooming In zoom lenses where the interval of
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, The radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21 , and the distance on the optical axis from the most object-side lens surface to the most image-side lens surface of the first lens group is D1, When the distance on the optical axis between the image side lens surface of the negative lens included in the first lens group and the object side lens surface of the positive lens included in the first lens group is d12 ,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
0.56 ≦ d12 / D1 <0.7
A zoom lens satisfying the following conditional expression: A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side, and are adjacent to each other during zooming In zoom lenses where the interval of
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The second lens group is composed of a positive lens and a cemented lens in which a positive lens and a negative lens are disposed in order from the object side to the image side.
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, When the radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
A zoom lens satisfying the following conditional expression: A first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, which are arranged in order from the object side to the image side, and are adjacent to each other during zooming In zoom lenses where the interval of
The first lens group includes a negative lens and a positive lens arranged in order from the object side to the image side,
The second lens group includes a positive lens, a cemented lens in which a positive lens and a negative lens are cemented, and a positive lens, which are arranged in order from the object side to the image side.
The focal length of the positive lens included in the first lens group is f1p, the focal length of the entire system at the wide angle end is fw, the radius of curvature of the image side lens surface of the negative lens included in the first lens group is r12, When the radius of curvature of the object-side lens surface of the positive lens included in the first lens group is r21,
4.6 <f1p / fw <9.0
−0.08 <(r12−r21) / (r12 + r21) <− 0.01
A zoom lens satisfying the following conditional expression: The distance on the optical axis from the most object side lens surface of the first lens group to the most image side lens surface is D1, and the image side lens surface and the first lens of the negative lens included in the first lens group When the distance on the optical axis of the lens surface on the object side of the positive lens included in the group is d12,
0.5 <d12 / D1 <0.7
The zoom lens according to claim 2, wherein the following conditional expression is satisfied. The third lens group is composed of a single positive lens, and when the radius of curvature of the object side lens surface and the image side lens surface of the positive lens included in the third lens group are r31 and r32, respectively.
0.40 <(r31-r32) / (r31 + r32) <0.95
The zoom lens according to any one of claims 1 to 4, characterized by satisfying the conditional expression. When the focal length of the third lens group is f3,
3.5 <f3 / fw <7.0
The zoom lens according to any one of claims 1 to 5, characterized by satisfying the conditional expression. When the lateral magnification at the wide angle end of the second lens group is β2w,
−0.58 <β2w <−0.30
The zoom lens according to any one of claims 1 to 6, characterized by satisfying the conditional expression. When the Abbe number of the material of the positive lens included in the first lens group is ν1p,
ν1p <20
The zoom lens according to any one of claims 1 to 7, characterized by satisfying the conditional expression. In the image blur correction, zooming according to any one of claims 1 to 8 all or part of the second lens group and wherein the moving in a direction having a component in a direction perpendicular to the optical axis lens.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that receives an image formed by the zoom lens.   The imaging apparatus according to claim 10, wherein an effective image circle diameter at the wide-angle end is smaller than an effective image circle diameter at the telephoto end.