JP2007219315A - Zoom lens with vibration proof function and imaging apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens with a vibration proof function which is compact, and has a large aperture ratio, a high variable power, a high angle of view at a wide angle end, and high focusing performance when camera shake is compensated. <P>SOLUTION: The zoom lens has, from an object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; a third lens group G3 having positive refractive power; a fourth lens group G4 having negative refractive power; and a fifth lens group G5 having positive refractive power. The zoom lens is characterized in that: the fifth lens group G5 is moved from the first lens group G1 when power is varied from a wide angle state W to a telephoto end state T; the fourth lens group G4 is composed of only one lens which is a cemented lens of a negative lens L41 and a positive lens L42; and a blur on an image face is compensated when the camera shake occurs, by moving the fourth lens group G4 in the direction substantially perpendicular to an optical axis. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zoom lens having a vibration isolation function used for a camera or the like.

2. Description of the Related Art Conventionally, zoom lenses having an anti-vibration function used for single-lens reflex cameras and the like are known in which a first lens group is configured with negative refractive power or positive refractive power. Among these, the zoom lens in which the first lens group has an anti-vibration function of positive refractive power is composed of five lens groups of positive refractive power, negative refractive power, positive refractive power, negative refractive power, and positive refractive power, and has a wide-angle end. Image plane when the camera shake occurs by moving the fourth lens unit having an angle of view of about 76 degrees and an F-number of about 3.5 to 4.5 and having a negative refractive power in a direction orthogonal to the optical axis. There has been proposed a zoom lens having an image stabilization function that corrects the upper image blur (hereinafter referred to as camera shake correction) (see, for example, Patent Document 1).
JP 2001-228397 A

  However, in the zoom lens in which the first lens group has a negative refractive power, it is difficult to shorten the entire length of the zoom lens in the wide-angle end state and to obtain a sufficient anti-vibration performance. Since the fourth lens group having negative refractive power, which is a group, is composed of a single lens, the imaging performance at the time of camera shake correction was insufficient.

  The present invention has been made in view of the above problems, and has a small size, a large aperture ratio, a high zoom ratio, a high angle of view at the wide-angle end state, and high imaging performance at the time of camera shake correction. An object of the present invention is to provide a zoom lens having an anti-vibration function. It is another object of the present invention to provide an image pickup apparatus equipped with a zoom lens having the image stabilization function. It is another object of the present invention to provide a camera shake correction method for a zoom lens having an anti-vibration function.

  In order to solve the above-described problems, the present invention provides, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative refractive power. The fourth lens group and the fifth lens group having a positive refractive power, and during zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, The distance between the second lens group and the third lens group is decreased, the distance between the third lens group and the fourth lens group is increased, and the distance between the fourth lens group and the fifth lens group is decreased; The fourth lens group is composed of only one cemented lens of a positive lens and a negative lens. By moving the fourth lens group in a direction substantially orthogonal to the optical axis, image blur correction on the image plane at the time of occurrence of camera shake is performed. Provided is a zoom lens having an anti-vibration function.

  The present invention also provides an image pickup apparatus equipped with the zoom lens having the image stabilization function.

  Further, according to the present invention, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a negative refractive power. A fifth lens unit having a positive refractive power, and when zooming from the wide-angle end state to the telephoto end state, an interval between the first lens unit and the second lens unit increases, and the second lens unit and the second lens unit The distance between the third lens group decreases, the distance between the third lens group and the fourth lens group increases, the distance between the fourth lens group and the fifth lens group decreases, and the fourth lens group In addition, the image forming apparatus includes only a single cemented lens of a positive lens and a negative lens, and performs image blur correction on an image plane when camera shake occurs by moving the fourth lens group in a direction substantially orthogonal to the optical axis. Provide an image stabilization method.

  According to the present invention, there is provided a zoom lens having an anti-vibration function that has a small size, a large aperture ratio, a high zoom ratio, a high angle of view at the wide-angle end state, and a high imaging performance at the time of camera shake correction can do. In addition, it is possible to provide an imaging apparatus equipped with a zoom lens having the image stabilization function. In addition, a camera shake correction method can be provided for a zoom lens having an anti-vibration function.

  Hereinafter, an image pickup apparatus (camera) equipped with a zoom lens having an image stabilization function according to the present invention will be described.

  FIG. 1 is a schematic configuration diagram of an image pickup apparatus (camera) equipped with a zoom lens having an image stabilization function according to the present invention described later.

  In FIG. 1, light from a subject (not shown) is collected by a zoom lens 11 having an anti-vibration function, which will be described later, reflected by a quick return mirror 12 and imaged on a focusing screen 13. The subject image formed on the focusing screen 13 is reflected by the pentaprism 14 a plurality of times, and can be viewed as an erect image by the photographer via the eyepiece lens 15.

  The photographer presses the release button fully after observing the subject image through the eyepiece lens 15 and determining the shooting composition while pressing the release button (not shown) halfway. When the release button is fully pressed, the quick return mirror 12 is flipped upward, the light from the subject is received by the image sensor (or film) 16 and a captured image is acquired and recorded in a memory (not shown).

  When the release button is fully pressed, the tilt of the camera 10 is detected by a sensor 17 (for example, an angle sensor) built in the zoom lens 11 and transmitted to the CPU 18, and the amount of rotation blur is detected by the CPU 18 for camera shake correction. The lens driving means 19 for driving the lens group in the direction orthogonal to the optical axis is driven to correct image blur on the image sensor 16 when camera shake occurs. In this way, the imaging apparatus 10 including the zoom lens 11 having a vibration-proof function described later is configured.

  Next, a zoom lens having an image stabilization function according to the present invention will be described.

  A zoom lens having an anti-vibration function according to the present invention (hereinafter simply referred to as a zoom lens) includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. The third lens group, the fourth lens group having a negative refractive power, and the fifth lens group having a positive refractive power, and the first lens group and the second lens upon zooming from the wide-angle end state to the telephoto end state The distance between the groups increases, the distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, and the distance between the fourth lens group and the fifth lens group decreases. Each lens group is moved, and the fourth lens group is composed of only one cemented lens of a positive lens and a negative lens. By moving the fourth lens group in a direction substantially orthogonal to the optical axis, camera shake occurs. In this configuration, image blur correction on the image plane (hereinafter referred to as camera shake correction) is performed.

  Thus, in the zoom lens according to the present invention, the fourth lens group is composed of only one cemented lens of a positive lens and a negative lens, so that the number of lenses is smaller than the other lens groups, and the lens diameter Therefore, the structure is suitable for incorporating a vibration isolation mechanism. As a result, high imaging performance can be ensured even during camera shake correction.

  In the zoom lens according to the present invention, it is desirable that the fourth lens group has an aspherical surface. In this way, an aspherical surface is arranged in the fourth lens group, and each lens group has an appropriate refractive power distribution, so that the imaging performance when the fourth lens group for camera shake correction is moved in a direction orthogonal to the optical axis is obtained. Can be sufficiently reduced.

  In the zoom lens according to the present invention, the first lens group, the third lens group, the fourth lens group, and the fifth lens group move monotonously in the object direction during zooming from the wide-angle end state to the telephoto end state. It is desirable to do. By moving the first, third, fourth, and fifth lens groups monotonously in the object direction in this way, the moving mechanism that moves the first, third, fourth, and fifth lens groups can be configured simply, It becomes possible to reduce the size of the zoom lens. Note that “monotonically moving in the object direction” means that the first, third, fourth, and fifth lens units move only in the object direction and do not move in the image plane direction during zooming from the wide-angle end state to the telephoto end state. That is, the movement trajectory is not limited to a straight line and may be a curved line.

It is desirable that the zoom lens according to the present invention satisfies the following conditional expression (1).
(1) -1.20 <f2 / fw <−0.76
However, fw is the focal length of the entire zoom lens system in the wide-angle end state, and f2 is the focal length of the second lens group.

  Conditional expression (1) defines the focal length of the second lens group with respect to the focal length of the entire zoom lens system in the wide-angle end state. If the lower limit of conditional expression (1) is not reached, it is advantageous for securing the back focus, but the field curvature aberration and astigmatism in the wide-angle end state deteriorate. If the upper limit value of conditional expression (1) is exceeded, the amount of movement of the second lens unit during zooming or focusing becomes large, and it becomes difficult to achieve downsizing of the zoom lens. Increasing the refractive power of other lens units other than the second lens unit in order to alleviate this effect deteriorates spherical aberration in the telephoto end state and makes it difficult to increase the aperture. If spherical aberration correction in the telephoto end state is performed on the aspherical surface included in the fourth lens group, it is not preferable because the vibration-proof performance is deteriorated due to decentering coma aberration. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (1) to −1.0. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (1) to −0.8.

It is desirable that the zoom lens according to the present invention satisfies the following conditional expression (2).
(2) 0.7 <f1 / ft <3.0
Here, ft is the focal length of the entire zoom lens system in the telephoto end state, and f1 is the focal length of the first lens group.

  Conditional expression (2) defines the focal length of the first lens group with respect to the focal length of the entire zoom lens system in the telephoto end state. If the lower limit value of conditional expression (2) is not reached, spherical aberration in the telephoto end state deteriorates, making it difficult to increase the diameter. If the upper limit of conditional expression (2) is exceeded, the outer diameter of the first lens group will increase, and the amount of movement of the first lens group during zooming will also increase, leading to an increase in the size of the zoom lens. Increasing the refractive power of the second lens group to alleviate this effect is not preferable because the field curvature aberration and astigmatism in the wide-angle end state deteriorate. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (2) to 1.2. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (2) to 2.5.

It is desirable that the zoom lens according to the present invention satisfies the following conditional expression (3).
(3) 0.38 <f3 / ft <0.60
Here, ft is the focal length of the entire zoom lens system in the telephoto end state, and f3 is the focal length of the third lens group.

  Conditional expression (3) defines the focal length of the third lens group with respect to the focal length of the entire zoom lens system in the telephoto end state. If the lower limit of conditional expression (3) is not reached, it is not preferable because the imaging performance deteriorates significantly due to manufacturing errors such as decentration between lens groups. In addition, the spherical aberration in the telephoto end state is also deteriorated, which is not preferable. If the upper limit value of conditional expression (3) is exceeded, the overall length and diameter of the zoom lens will increase, making it difficult to put to practical use. In addition, it is not preferable because the diaphragm mechanism and the vibration isolation mechanism are increased in size. Increasing the refractive power of the second lens unit to alleviate this effect is not preferable because off-axis aberrations such as field curvature aberration and astigmatism in the wide-angle end state are deteriorated. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (3) to 0.42. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (3) to 0.55.

It is desirable that the zoom lens according to the present invention satisfies the following conditional expression (4).
(4) 0.55 <f5 / ft <1.50
Here, ft is the focal length of the entire zoom lens system in the telephoto end state, and f5 is the focal length of the fifth lens group.

  Conditional expression (4) defines the focal length of the fifth lens group with respect to the focal length of the entire zoom lens system in the telephoto end state. If the lower limit of conditional expression (4) is not reached, it is not preferable because the imaging performance deteriorates significantly due to manufacturing errors such as decentration between lens groups. In addition, the spherical aberration in the telephoto end state is also deteriorated, which is not preferable. If the upper limit value of conditional expression (4) is exceeded, the refractive power of the fourth lens group becomes weak, and the amount of image movement on the image plane with respect to the amount of movement of the fourth lens group during image stabilization becomes small. For this reason, the amount of movement in the direction perpendicular to the optical axis of the fourth lens group for obtaining the amount of image movement necessary for image stabilization becomes large, and it is difficult to correct image plane fluctuation and decentering coma during image stabilization. Become. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (4) to 0.80. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (4) to 1.30.

It is desirable that the zoom lens according to the present invention satisfies the following conditional expression (5).
(5) | β5t | <0.24
Here, β5t is the imaging magnification of the fifth lens group in the telephoto end state.

  Conditional expression (5) relates to imaging performance when the fourth lens group, which is a camera shake correction lens group, is moved in a direction substantially orthogonal to the optical axis. When the upper limit value of conditional expression (5) is exceeded, the fluctuation of the field curvature aberration when the fourth lens unit is moved in the direction substantially orthogonal to the optical axis increases, resulting in deterioration of imaging performance. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (5) to 0.20.

  The zoom lens according to the present invention has at least two surfaces in the fifth lens group in order to satisfactorily correct distortion, field curvature and astigmatism at the wide-angle end state, and spherical aberration and coma at the telephoto end. It is desirable to have an aspheric surface.

  In the zoom lens according to the present invention, it is desirable to perform focusing from an object at infinity to a near object by moving the second lens group in the object direction. By making the second lens group a focusing lens group, it is possible to achieve downsizing.

  The image stabilization method according to the present invention includes a first lens unit having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative refractive power in order from the object side. A fourth lens group and a fifth lens group having positive refracting power, and when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases; The distance between the second lens group and the third lens group decreases, the distance between the third lens group and the fourth lens group increases, the distance between the fourth lens group and the fifth lens group decreases, The fourth lens group includes only one cemented lens of a positive lens and a negative lens, and is realized by moving the fourth lens group in a direction substantially orthogonal to the optical axis.

  As described above, in the camera shake correction method according to the present invention, the fourth lens group is configured by only one cemented lens of a positive lens and a negative lens, and thus the number of lenses is smaller than the other lens groups, and Since the lens diameter can be reduced and the weight can be reduced, the vibration isolation mechanism can be easily configured. As a result, high imaging performance can be ensured even during camera shake correction.

  In the camera shake correction method according to the present invention, it is desirable that the fourth lens group has an aspherical surface. By disposing an aspherical surface in the fourth lens group and making each lens group have an appropriate refractive power distribution, the imaging performance when the fourth lens group for camera shake correction is moved in the direction orthogonal to the optical axis is reduced. It can be made sufficiently small.

"Example"
Embodiments of a zoom lens having an image stabilization function according to an embodiment of the present invention (hereinafter simply referred to as a zoom lens) will be described below with reference to the drawings.

(First embodiment)
FIG. 2 is a lens configuration diagram of the zoom lens according to the first example of the present invention.

  In FIG. 2, the zoom lens according to the first example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. A third lens group G3 having a negative refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group having a positive refractive power, and at the time of zooming from the wide-angle end state W to the telephoto end state T The air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the air between the third lens group G3 and the fourth lens group G4. The first lens group G1, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are objects so that the distance increases and the air distance between the fourth lens group G4 and the fifth lens group G5 decreases. The second lens group G2 moves in the direction.

  The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. .

  In order from the object side, the second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a cemented lens of a biconcave negative lens L22 and a biconvex positive lens L23, and the image plane I side. A negative meniscus lens L24 having a convex surface facing the surface and a biconvex positive lens L25, and an aspherical surface is formed on the surface closest to the object side of the second lens group G2.

  The third lens group G3 includes, in order from the object side, a cemented lens of a biconvex positive lens L31, a biconvex positive lens L32, and a negative meniscus lens L33 having a convex surface facing the image side, and a convex surface on the object side. And a positive meniscus lens L34.

  The fourth lens group G4 includes, in order from the object side, a cemented lens of a biconcave negative lens L41 and a positive meniscus lens L42 having a convex surface directed toward the object side, and is positioned closest to the object side of the fourth lens group G4. An aspheric surface is formed on the surface. Image blur correction on the image plane I when camera shake occurs is performed by moving the entire fourth lens group G4 in a direction substantially orthogonal to the optical axis.

  The fifth lens group G5 includes, in order from the object side, a cemented lens of a biconvex positive lens L51, a biconcave negative lens L52, and a biconvex positive lens L53, and is the most of the fifth lens group G5. An aspheric surface is formed on the object side surface and the image surface I side surface of the biconvex positive lens L51 located on the object side.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state W to the telephoto end state T. Further, focusing from a long distance object to a short distance object is performed by moving the second lens group G2 in the object direction.

  Note that the focal length of the entire zoom lens system is f, and the image stabilization coefficient (ratio of the amount of movement of the image on the imaging surface to the amount of movement of the lens unit for camera shake correction) is K and the rotational blurring at an angle θ. Can be corrected by moving the camera-shake correction moving lens group in the direction orthogonal to the optical axis by (f · tan θ) / K. In the first embodiment, in the wide-angle end state, the image stabilization coefficient K is 0.646, and the focal length is 24.7 (mm). Therefore, the fourth lens group for correcting the rotation blur of 0.60 °. The amount of movement is 0.558 (mm). In the telephoto end state of the first embodiment, since the image stabilization coefficient K is 0.913 and the focal length is 68.0 (mm), the fourth for correcting the rotation blur of 0.40 °. The amount of movement of the lens group is 0.520 (mm).

Table 1 below lists values of specifications of the zoom lens according to the first example. In Table 1, f in [Overall specifications] represents a focal length, FNO represents an F number, and 2ω represents an angle of view (unit: degree). In [lens specifications], N is the number of the lens surface from the object side, r is the radius of curvature of the lens surface, d is the distance between the lens surfaces, νd is the Abbe number with respect to the d-line (wavelength λ = 587.6 nm), and nd is d Refractive index for each line (wavelength λ = 587.6 nm) is shown. Note that r = ∞ is a plane, and air refractive index nd = 1.00000 is omitted. [Aspherical data] shows the aspherical coefficient when the aspherical shape is expressed by the following equation.
X = (h2 / r) / [1+ {1-κ (h / r) 2} 1/2]
+ C4 × h4 + C6 × h6 + C8 × h8 + C10 × h10
X is the displacement (sag amount) in the optical axis direction at the position of the height h from the optical axis with respect to the apex of the surface, κ is the conic constant, and C4, C6, C8, and C10 are the fourth order, respectively. , 6th order, 8th order, and 10th order aspherical coefficients, and r represents the radius of curvature (paraxial curvature radius) of the reference spherical surface. In [Variable interval data], the focal length f, the variable intervals D1, D2, D3, D4, and the value of the back focus Bf are shown. In [Conditional Expression Corresponding Value], the corresponding value of each conditional expression is shown.

  In all the following specification values, “mm” is generally used as the focal length f, radius of curvature r, surface interval d and other lengths, etc. unless otherwise specified, but the optical system is proportional. Even if it is enlarged or proportionally reduced, the same optical performance can be obtained. Further, the unit is not limited to “mm”, and other appropriate units may be used. Further, the explanation of these symbols is the same in the other embodiments, and the explanation is omitted.

(Table 1)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
f = 24.7 to 49.8 to 68.0
FNO = 2.9 to 2.9 to 2.9
2ω = 84.7 to 46.2 to 34.6

[Lens specifications]
N rd νd nd
1 381.9142 2.4000 23.78 1.846660
2 138.6720 5.8205 81.54 1.496999
3 -11570.531 0.1000
4 67.7649 5.5672 46.57 1.804000
5 161.0698 (D1)
6 -13924.671 0.2000 38.09 1.553890 Aspheric
7 146.4274 1.5000 46.62 1.816000
8 21.4764 8.1047
9 -75.8155 7.4055 42.71 1.834807
10 1193.3616 3.3852 30.13 1.698947
11 -50.9825 2.7169
12 -24.2159 1.2000 42.71 1.834807
13 -233.1473 0.1000
14 539.2621 4.0149 25.42 1.805181
15 -43.7163 (D2)
16 ∞ 1.0000 Aperture stop S
17 137.4710 4.2638 54.68 1.729157
18 -67.4961 0.1000
19 48.7389 7.1898 81.54 1.496999
20 -46.3514 1.2000 23.78 1.846660
21 -218.5208 0.1000
22 65.6556 2.2476 54.68 1.729157
23 130.4309 (D3)
24 -110.2724 0.1000 38.09 1.553890 Aspheric
25 -123.4095 1.2000 46.62 1.816000
26 46.5464 2.9864 23.78 1.846660
27 145.9441 2.5238
28 ∞ (D4)
29 69.4891 6.5242 49.34 1.743198 Aspheric
30 -37.3564 0.1000 Aspheric
31 -57.5038 1.2000 37.16 1.834000
32 24.2899 8.7487 65.44 1.603001
33 -74.3225 (BF)

[Aspherical data]
Face κ C4 C6 C8 C10
6 1.0000 1.06970E-05 -7.94520E-09 1.63850E-12 1.45260E-14
24 1.9068 2.53860E-06 -6.93630E-10 0.00000E + 00 0.00000E + 00
29 -8.1986 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
30 -1.2933 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 24.7 49.8 68.0
D1 3.71536 27.06548 39.18882
D2 27.95448 6.58124 1.00049
D3 5.19221 10.33443 11.28405
D4 13.51561 2.95077 1.00000
BF 38.00007 54.85371 63.28902

[Conditional expression values]
(1) -0.954
(2) 2.167
(3) 0.531
(4) 1.029
(5) 0.005

  3A and 3B show various aberration diagrams of the zoom lens according to the first example in the infinite focus state. FIG. 3A shows various aberration diagrams in the wide-angle end state, and FIG. The meridional lateral aberration diagram when rotational shake correction is performed for 60 ° rotational shake is shown. FIG. 4 is a diagram illustrating various aberrations of the zoom lens according to the first example in the intermediate focal length state at the infinite focus state. FIGS. 5A and 5B show various aberration diagrams of the zoom lens according to the first example in the infinite focus state. FIG. 5A shows various aberration diagrams in the telephoto end state, and FIG. A meridional transverse aberration diagram when rotational shake correction is performed for 40 ° rotational shake is shown. In each aberration diagram, FNO is an F number, A is a half angle of view (unit: degree), d is a d-line (wavelength λ = 587.6 nm), and g is a g-line (wavelength λ = 435.6 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The description of these symbols is the same in the other examples below, and the description is omitted.

  From each aberration diagram, it is clear that the zoom lens according to the first example has excellent imaging performance with various aberrations corrected well.

"Second Example"
FIG. 6 shows a lens configuration diagram of a zoom lens according to the second embodiment of the present invention.

  In FIG. 6, the zoom lens according to the second example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. A third lens group G3 having a negative refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power, and zooming from the wide-angle end state W to the telephoto end state T At this time, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 and the fourth lens group G4. The first lens group G1, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are arranged so that the air gap increases and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. The second lens group G2 moves in the object direction.

  The first lens group G1 is composed of, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. .

  The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a convex surface directed toward the object side, a positive meniscus lens L22 having a convex surface directed toward the image surface I, and a negative meniscus having a convex surface directed toward the image surface I. An aspherical surface is formed on the surface closest to the object side of the second lens group G2, which includes the meniscus lens L23 and the positive biconvex lens L24.

  The third lens group G3 includes, in order from the object side, a biconvex positive lens L31, a cemented lens of a biconvex positive lens L32, and a negative meniscus lens L33 having a convex surface facing the image plane I, and the object side. And a positive meniscus lens L34 having a convex surface facing the surface.

  The fourth lens group G4 includes, in order from the object side, a cemented lens of a biconcave negative lens L31 and a positive meniscus lens L32 having a convex surface directed toward the object side, and is a surface located closest to the object side in the fourth lens group. Has an aspheric surface. In addition, image blur correction on the image plane I at the time of occurrence of camera shake is performed by moving the entire fourth lens group G4 in a direction substantially orthogonal to the optical axis.

  The fifth lens group G5 includes, in order from the object side, a cemented lens of a negative meniscus lens L51 having a convex surface directed toward the object side and a biconvex positive lens L52, a biconcave negative lens L53, and a biconvex shape. An aspheric surface is formed on the most object side surface of the fifth lens group G5 and the most image side surface of the fifth lens group G5.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state W to the telephoto end state T. Focusing from a long-distance object to a short-distance object is performed by moving the second lens group G2 in the object direction.

  Note that the focal length of the entire zoom lens system is f, and the image stabilization coefficient (ratio of the amount of movement of the image on the imaging surface to the amount of movement of the lens unit for camera shake correction) is K and the rotational blurring at an angle θ. Is corrected by moving the lens group for camera shake correction by (f · tan θ) / K in the direction orthogonal to the optical axis. In the wide-angle end state of the second embodiment, since the image stabilization coefficient K is 0.613 and the focal length is 24.7 (mm), the fourth lens group for correcting the rotation blur of 0.60 °. The moving amount of G4 is 0.422 (mm). Further, in the telephoto end state of the second embodiment, the image stabilization coefficient K is 0.793 and the focal length is 68.0 (mm), so the fourth for correcting the rotation blur of 0.40 °. The moving amount of the lens group G4 is 0.599 (mm).

  Table 2 below provides values of specifications of the zoom lens according to the second example.

(Table 2)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
f = 24.7 to 49.8 to 68.0
FNO = 2.9 to 2.9 to 2.9
2ω = 85.0 to 46.0 to 34.4

[Lens specifications]
N rd νd nd
1 393.3547 2.4000 32.35 1.850 260
2 121.1245 7.3965 81.54 1.496999
3 -699.2649 0.1000
4 64.0104 6.0609 54.68 1.729157
5 166.9671 (D1)
6 -2590.5471 0.2000 38.09 1.553890 Aspheric
7 151.7884 1.5000 46.62 1.816000
8 20.8193 8.3127
9 -46.3928 10.0000 23.78 1.846660
10 -38.3556 1.8563
11 -24.1256 1.2000 42.71 1.834807
12 -178.0687 0.1000
13 504.5206 3.4348 23.78 1.846660
14 -54.8328 (D2)
15 ∞ 1.0000 Aperture stop S
16 177.2706 3.4866 81.54 1.496999
17 -70.7325 0.1000
18 68.2727 5.6917 81.54 1.496999
19 -46.9258 1.2000 23.78 1.846660
20 -91.1462 0.1000
21 40.2330 4.0408 81.54 1.496999
22 349.0861 (D3)
23 -94.8264 0.1000 38.09 1.553890 Aspheric
24 -103.1162 1.2000 65.44 1.603001
25 47.5059 1.9461 23.78 1.846660
26 83.4223 2.5000
27 ∞ (D4)
28 48.2697 1.2000 37.16 1.834000 Aspherical
29 23.8465 10.5294 81.54 1.496999
30 -49.1956 0.1000
31 -138.2143 1.2000 37.16 1.834000
32 95.8943 0.5418
33 131.6243 3.8789 65.44 1.603001
34 -66.1940 BF Aspherical surface

[Aspherical data]
Face κ C4 C6 C8 C10
6 0.0000 1.18680E-05 -8.91840E-09 -2.42300E-12 3.50550E-14
23 1.1505 2.41070E-06 -9.33550E-10 0.00000E + 00 0.00000E + 00
28 -2.8808 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
34 -6.2937 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 24.7 49.8 68.0
D1 3.40508 26.34155 38.22074
D2 27.74015 6.53201 1.00207
D3 5.05305 10.16700 11.22391
D4 12.99288 2.89230 1.00000
BF 38.00014 55.18211 63.27100

[Conditional expression values]
(1) -0.931
(2) 2.051
(3) 0.510
(4) 1.229
(5) 0.195

  7A and 7B show various aberration diagrams of the zoom lens according to the second example in the infinite focus state. FIG. 7A shows various aberration diagrams in the wide-angle end state, and FIG. The meridional lateral aberration diagram when rotational shake correction is performed for 60 ° rotational shake is shown. FIG. 8 is a diagram illustrating various aberrations of the zoom lens according to the second example in the intermediate focal length state at the infinity in-focus state. FIG. 9 shows various aberration diagrams of the zoom lens according to the second example in the infinite focus state. FIG. 9A shows various aberration diagrams in the telephoto end state, and FIG. A meridional transverse aberration diagram when rotational shake correction is performed for 40 ° rotational shake is shown.

  From the respective aberration diagrams, it is clear that the zoom lens according to the second example has excellent imaging performance with various aberrations corrected well.

(Third embodiment)
FIG. 10 is a lens configuration diagram of a zoom lens according to the third example of the present invention.

  In FIG. 10, the zoom lens according to the third example includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. A third lens group G3 having a negative refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power, and zooming from the wide-angle end state W to the telephoto end state T At this time, the air gap between the first lens group G1 and the second lens group G2 increases, the air gap between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 and the fourth lens group G4. The first lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 are arranged so that the air gap increases and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. The second lens group G2 moves in the object direction.

  The first lens group G1 includes, in order from the object side, a cemented lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side.

  In order from the object side, the second lens group G2 includes a negative meniscus lens L21 having a convex surface directed toward the object side, a cemented lens of a biconcave negative lens L22 and a biconvex positive lens L23, and the image plane I side. A negative meniscus lens L24 having a convex surface directed toward the image surface I and a negative meniscus lens L25 having a convex surface directed toward the image surface I, and an aspherical surface is formed on the surface closest to the object side of the second lens group G2.

  The third lens group G3 includes, in order from the object side, a cemented lens of a negative meniscus lens L31 having a convex surface directed toward the object side and a biconvex positive lens L32, a biconvex positive lens L33, and a convex surface toward the object side. And a positive meniscus lens L34.

  The fourth lens group G4 includes, in order from the object side, a cemented lens of a biconcave negative lens L41 and a positive meniscus lens L42 having a convex surface directed toward the object side, and is positioned closest to the object side of the fourth lens group G4. An aspheric surface is formed on the surface. Image blur correction on the image plane I at the time of occurrence of camera shake is performed by moving the entire fourth lens group in a direction orthogonal to the optical axis.

  The fifth lens group G5 includes, in order from the object side, a cemented lens of a negative meniscus lens L51 having a convex surface directed toward the object side and a biconvex positive lens L52, a negative meniscus lens L53 having a convex surface directed toward the object side, An aspherical surface is formed on the most object side surface of the fifth lens group G5 and the most image surface I side surface of the fifth lens group G5.

  The aperture stop S is located between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 upon zooming from the wide-angle end state W to the telephoto end state T. Focusing from a long-distance object to a short-distance object is performed by moving the second lens group G2 in the object direction.

  Note that the focal length of the entire zoom lens system is f, and the image stabilization coefficient (ratio of the amount of movement of the image on the imaging surface to the amount of movement of the lens unit for camera shake correction) is K and the rotational blurring at an angle θ. Is corrected by moving the lens group for camera shake correction by (f · tan θ) / K in the direction orthogonal to the optical axis. In the third embodiment, in the wide-angle end state, the image stabilization coefficient K is 0.617 and the focal length is 24.7 (mm). Therefore, the fourth lens group for correcting the rotation blur of 0.60 °. The moving amount of G4 is 0.419 (mm). In the telephoto end state of the third embodiment, since the image stabilization coefficient K is 0.811 and the focal length is 68.0 (mm), the fourth lens for correcting the rotation blur of 0.40 °. The movement amount of the group G4 is 0.585 (mm).

  Table 3 below provides values of specifications of the zoom lens according to the third example.

(Table 3)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
f = 24.7 to 49.8 to 68.0
FNO = 2.9 to 2.9 to 2.9
2ω = 84.7 to 46.1 to 34.4

[Lens specifications]
N rd νd nd
1 394.4573 2.4000 32.35 1.850 260
2 109.4234 7.4301 81.54 1.496999
3 -392.0430 0.1000
4 61.9189 5.3766 54.68 1.729157
5 155.6449 (D1)
6 792.4535 0.2000 38.09 1.553890 Aspheric
7 140.2581 1.5000 42.71 1.834807
8 19.9365 8.3384
9 -49.4278 1.2307 53.20 1.693501
10 23.8805 6.7359 32.35 1.850 260
11 -63.4325 2.2319
12 -26.9636 1.2000 81.54 1.496999
13 -37.2035 1.2667
14 -26.5495 1.2000 81.54 1.496999
15 -43.9514 (D2)
16 ∞ 1.0000 Aperture stop S
17 79.3488 1.2000 23.78 1.846660
18 38.6696 5.6726 81.54 1.496999
19 -92.2478 0.1000
20 75.2763 3.4019 65.44 1.603001
21 -272.7362 0.1000
22 44.5998 4.1531 65.44 1.603001
23 3749.0646 (D3)
24 -139.0237 0.1000 38.09 1.553890 Aspheric
25 -153.6935 1.2000 39.58 1.804398
26 30.3643 3.8242 25.42 1.805181
27 139.5369 2.5000
28 ∞ (D4)
29 38.7061 1.2000 37.16 1.834000 Aspheric
30 24.4109 8.2513 81.54 1.496999
31 -76.1159 0.1000
32 394.0143 1.2000 32.35 1.850 260
33 55.8295 1.2166
34 101.9126 4.2230 81.54 1.496999
35 -62.5210 BF Aspherical surface

[Aspherical data]
Face κ C4 C6 C8 C10
6 0.0000 1.02000E-05 -7.13240E-09 -5.21350E-13 2.50420E-14
24 0.8895 1.57600E-06 7.14360E-10 5.13380E-12 -1.96130E-14
29 -0.7051 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00
35 -7.3960 0.00000E + 00 0.00000E + 00 0.00000E + 00 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state
f 24.7 49.8 68.0
D1 2.99650 22.93441 36.29599
D2 23.62964 5.17440 1.00000
D3 4.54821 9.78442 10.62371
D4 14.87229 3.07940 1.00000
BF 38.00015 56.92888 64.00011

[Conditional expression values]
(1) -0.852
(2) 1.963
(3) 0.494
(4) 1.073
(5) 0.032

  11A and 11B show various aberration diagrams of the zoom lens according to the third example in the infinite focus state. FIG. 11A shows various aberration diagrams in the wide-angle end state, and FIG. The meridional lateral aberration diagram when rotational shake correction is performed for 60 ° rotational shake is shown. FIG. 12 is a diagram illustrating various aberrations of the zoom lens according to the third example in the intermediate focal length state at the infinite focus state. FIGS. 13A and 13B are graphs showing various aberrations of the zoom lens according to the third example in the infinite focus state. FIG. 13A is a diagram showing various aberrations in the telephoto end state, and FIG. A meridional transverse aberration diagram when rotational shake correction is performed for 40 ° rotational shake is shown.

  From each aberration diagram, it is clear that the zoom lens according to the third example has excellent image forming performance with various aberrations corrected satisfactorily.

  As an example of the present invention, a lens system having a five-group configuration is shown. However, a lens system in which an additional lens group is added to the five groups is also an equivalent lens system in which the effects of the present invention are inherent. Needless to say. In addition, in the configuration within each lens group, it goes without saying that a lens group in which an additional lens is added to the configuration of the embodiment is an equivalent lens group in which the effects of the present invention are inherent.

  In all of the embodiments, the second lens group is described as a focusing lens group, but other single or plural lens groups or partial lens groups are moved in the optical axis direction so as to be close to an object at infinity. A focusing lens group that focuses on a distance object may be used. The focusing lens group can also be applied to autofocus, and is also suitable for driving a motor for autofocus (such as an ultrasonic motor).

  In all the embodiments, the fourth lens group is described as an anti-vibration lens group. However, image blur caused by camera shake is caused by vibrating other lens groups or partial lens groups in a direction perpendicular to the optical axis. A vibration-proof lens group to be corrected may be used.

  In addition, a lens surface other than the aspheric surface shown in all the embodiments may be an aspheric surface. The aspherical surface may be any of an aspherical surface by grinding, a glass mold aspherical surface in which a glass is formed into an aspherical shape, or a composite aspherical surface in which a resin is formed in an aspherical shape on the glass surface.

  Further, each lens surface is provided with an antireflection film having a high transmittance over a wide wavelength range, and flare and ghost can be reduced to achieve high optical performance with high contrast.

  According to the present invention, the zoom lens has an anti-vibration function. The F-number has a brightness of about 2.9 over the entire zoom range, a zoom ratio of about 2.7, and 80 ° in the wide-angle end state. It is possible to provide a zoom lens having the above-described angle of view and having a vibration-proof function that is small and has high image performance.

  The above-described embodiment is merely an example, and is not limited to the above-described configuration and shape, and can be appropriately modified and changed within the scope of the present invention.

1 is a schematic configuration diagram of an imaging apparatus equipped with a zoom lens having an image stabilization function according to the present invention. 1 is a lens configuration diagram of a zoom lens according to a first example of the present invention. FIG. FIG. 6A shows various aberration diagrams of the zoom lens according to the first example in the infinite focus state, FIG. 5A shows various aberration diagrams in the wide-angle end state, and FIG. 6B shows 0.60 ° rotation in the wide-angle end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown. FIG. 6 shows various aberration diagrams in the intermediate focal length state when the zoom lens according to the first example is in focus at infinity. FIG. 5A illustrates various aberration diagrams of the zoom lens according to the first example in the infinite focus state, FIG. 10A illustrates various aberration diagrams in the telephoto end state, and FIG. 10B illustrates 0.40 ° rotation in the telephoto end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown. FIG. 4 is a lens configuration diagram of a zoom lens according to a second example of the present invention. FIG. 7A illustrates various aberration diagrams of the zoom lens according to the second embodiment in the infinite focus state, FIG. 10A illustrates various aberration diagrams in the wide-angle end state, and FIG. 9B illustrates 0.60 ° rotation in the wide-angle end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown. FIG. 6 shows various aberration diagrams in the intermediate focal length state when the zoom lens according to the second example is in focus at infinity. FIG. 9A shows various aberration diagrams of the zoom lens according to the second embodiment in the infinite focus state, FIG. 10A shows various aberration diagrams in the telephoto end state, and FIG. 9B shows 0.40 ° rotation in the telephoto end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown. FIG. 6 shows a lens configuration diagram of a zoom lens according to a third example of the present invention. FIG. 9A shows various aberration diagrams of the zoom lens according to the third example in the infinite focus state, FIG. 10A shows various aberration diagrams in the wide-angle end state, and FIG. 9B shows 0.60 ° rotation in the wide-angle end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown. FIG. 10 shows various aberration diagrams in the intermediate focal length state when the zoom lens according to Example 3 is in focus at infinity. FIG. 7A shows various aberration diagrams of the zoom lens according to the third example in an infinite focus state, FIG. 10A shows various aberration diagrams in the telephoto end state, and FIG. 10B shows 0.40 ° rotation in the telephoto end state. The meridional lateral aberration diagram when the rotational shake correction for the shake is performed is shown.

Explanation of symbols

10 Imaging device (camera)
11 Zoom lens with anti-vibration function (zoom lens)
12 Quick Return Mirror 13 Focusing Plate 14 Penta Prism 15 Eyepiece 16 Image Sensor 17 Sensor (Angle Sensor)
18 CPU
19 Lens driving means G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group S Aperture stop I Image surface

Claims (13)

In order from the object side, a first lens unit having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a first lens unit having a positive refractive power. Having 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group decreases. The distance between the lens group and the fourth lens group is increased, and the distance between the fourth lens group and the fifth lens group is decreased;
The fourth lens group is composed of only one cemented lens of a positive lens and a negative lens. By moving the fourth lens group in a direction substantially orthogonal to the optical axis, image blur correction on the image plane at the time of occurrence of camera shake is performed. A zoom lens having an anti-vibration function.   The zoom lens having an anti-vibration function according to claim 1, wherein the fourth lens group has an aspherical surface.   When zooming from the wide-angle end state to the telephoto end state, the first lens group, the third lens group, the fourth lens group, and the fifth lens group move monotonously in the object direction. A zoom lens having the image stabilization function according to claim 1. The zoom lens having the image stabilization function according to any one of claims 1 to 3, wherein the following condition is satisfied.
−1.0 <f2 / fw <−0.8
However,
fw: focal length of the entire zoom lens system having the image stabilization function in the wide-angle end state;
f2: focal length of the second lens group. The zoom lens having the image stabilization function according to claim 1, wherein the zoom lens satisfies the following condition.
0.7 <f1 / ft <3.0
However,
ft: focal length of the entire zoom lens system having the image stabilization function in the telephoto end state,
f1: Focal length of the first lens group. The zoom lens having an image stabilization function according to claim 1, wherein the zoom lens satisfies the following condition.
0.38 <f3 / ft <0.60
However,
ft: focal length of the entire zoom lens system having the image stabilization function in the telephoto end state,
f3: focal length of the third lens group. The zoom lens having an anti-vibration function according to claim 1, wherein the zoom lens satisfies the following condition.
0.55 <f5 / ft <1.50
However,
ft: focal length of the entire zoom lens system having the image stabilization function in the telephoto end state,
f5: focal length of the fifth lens group. The zoom lens having the image stabilization function according to claim 1, wherein the zoom lens satisfies the following condition.
| Β5t | <0.24
However,
β5t: Imaging magnification of the fifth lens group in the telephoto end state.   9. The zoom lens having an anti-vibration function according to claim 1, wherein the fifth lens group has at least two aspheric surfaces. 10.   10. The zoom lens having an anti-vibration function according to claim 1, wherein the second lens group is moved in an optical axis direction when focusing from an object at infinity to an object at a short distance. .   An image pickup apparatus comprising the zoom lens having the image stabilization function according to claim 1. In order from the object side, a first lens unit having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a first lens unit having a positive refractive power. Having 5 lens groups,
During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group increases, the distance between the second lens group and the third lens group decreases, and the third lens group decreases. The distance between the lens group and the fourth lens group is increased, the distance between the fourth lens group and the fifth lens group is decreased, and the fourth lens group is composed of only one cemented lens of a positive lens and a negative lens. Become
A camera shake correction method, wherein image blur correction on an image plane when camera shake occurs is performed by moving the fourth lens group in a direction substantially orthogonal to the optical axis.   The camera shake correction method according to claim 12, wherein the fourth lens group has an aspherical surface.

Images