JP2010072051A - Zoom lens and image pickup device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens having a compact entire lens system and capable of obtaining high optical performance in the entire zoom range, and to provide an image pickup device including the same. <P>SOLUTION: In the zoom lens including a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power, in order from an object side to an image side, wherein the intervals between the respective lens groups change upon zooming, the first lens group includes a positive eleventh lens, a negative twelfth lens, and a positive thirteenth lens in order from the object side to the image side. The radius of curvature R1 of the surface at the object side and the radius of curvature R2 at the image side of the eleventh lens, imaging magnifications β2W, β2T of the second lens group at a wide-angle end and a telephoto end, and imaging magnifications β3W, β3T of the third lens group at the wide-angle end and the telephoto end are properly set, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  Recently, imaging devices (cameras) such as a video camera and a digital still camera using a solid-state imaging device have been highly functionalized and miniaturized.

  As the imaging device becomes more functional and smaller, the optical system used for the imaging device is required to be a small zoom lens having high optical performance with a large aperture ratio including a wide angle of view (shooting angle of view). ing.

  In addition, in this type of camera, various optical members such as a low-pass filter and a color correction filter are disposed between the last lens portion and the image sensor. For this reason, a zoom lens used therefor is required to have a relatively long back focus.

  Furthermore, in the case of a color camera using a color image pickup device, it is desired that the image side has a good telecentric characteristic in order to avoid color shading.

  As a zoom lens with a compact overall system, long back focus, and good telecentric characteristics on the image side, a negative lead type zoom lens that is preceded by a lens unit with negative refractive power (located closest to the object side) is known. Yes.

  As a negative lead type zoom lens, in order from the object side to the image side, three groups 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 Zoom lenses are known (Patent Documents 1 to 5).

  In this three-group zoom lens, there is known a zoom lens in which the first lens group having a negative refractive power is configured by a positive lens, a negative lens, and a positive lens in order from the object side to the image side to obtain good optical performance. (Patent Documents 6 to 8).

On the other hand, in recent years, in an imaging apparatus, correction of distortion among optical aberrations of a zoom lens is not performed optically but is corrected by image processing electrically. This reduces distortion that often occurs when widening the angle of view.
JP 2004-061675 A JP 2004-094283 A JP 2004-239974 A JP 2004-318104 A JP-A-2005-331641 JP 2002-023053 A JP 2002-090625 A JP 2000-137164 A

  In recent years, zoom lenses for use in video cameras, digital cameras, and the like have been strongly demanded to have a small size and high optical performance as the performance of an image sensor increases.

  In recent years, in order to reduce the size of the camera and increase the zoom ratio of the zoom lens used in many cameras, the distance between the lens groups during non-shooting is reduced to a different distance from the shooting state. A so-called collapsible type is used to reduce the amount of protrusion.

  At this time, if the number of lenses in each lens group constituting the zoom lens is large, the length of each lens group on the optical axis becomes long (the total lens length becomes long). As a result, the desired retractable length cannot be obtained, and it becomes difficult to use the retractable type. In this tendency, as the zoom ratio of the zoom lens increases, the total length of the lens becomes longer and it becomes difficult to apply the retractable type.

  In the negative lead type three-group zoom lens described above, in order to reduce the size of the entire system, to reduce the size when the lens is retracted, and to further increase the zoom ratio, the number of lenses in each lens group constituting the zoom lens is reduced. It is effective to increase the refractive power of the lens group.

  However, for example, if the refractive power of each lens group is simply increased in order to increase the zoom ratio, aberration fluctuations associated with zooming increase, making it difficult to obtain high optical performance over the entire zoom range.

  Therefore, in a negative lead type three-group zoom lens, in order to achieve a reduction in size of the entire system, a wide angle of view, and a high zoom ratio, the lens configuration of each lens group, refractive power arrangement, and zooming are performed. It is important to appropriately set the movement locus of each lens group.

  For example, if the lens configuration of the first lens group and the imaging magnification at the wide-angle end and the telephoto end of the second and third lens groups are not set appropriately, the entire system can be reduced in size and wide-angle, while achieving high optical performance. Getting performance is very difficult.

  An object of the present invention is to provide a zoom lens in which the entire lens system is compact and high optical performance can be obtained in the entire zoom range, and an image pickup apparatus having the zoom lens.

The zoom lens of the present invention includes, in order from the object side to the image side, 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.
During zooming, in zoom lenses where the distance between each lens group changes,
The first lens group includes, in order from the object side to the image side, a positive eleventh lens, a negative twelfth lens, and a positive thirteenth lens. The radius of curvature of the object side surface of the eleventh lens is R1, The radius of curvature of the image side surface is R2, the imaging magnification of the second lens group at the wide-angle end and the telephoto end is β2W and β2T, respectively, and the imaging magnification of the third lens group at the wide-angle end and the telephoto end is β3W, respectively. When β3T is assumed,
0 <(R1-R2) / (R1 + R2) <5.5
2.55 <(β2T · β3W) / (β2W · β3T) <3.50
It is characterized by satisfying the following conditions.

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

  Next, the zoom lens of the present invention and the image pickup apparatus having the same will be described.

  The zoom lens according to the present invention includes, in order from the object side to the image side, 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. Yes. In zooming, the distance between the lens groups changes.

  Specifically, during zooming from the wide-angle end to the telephoto end, the first lens group moves along a convex locus toward the image side, the second lens group moves monotonously toward the object side, and the third lens group moves toward the image side. Move monotonically.

  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. 2, 3, and 4 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.

  Example 1 is a zoom lens having a zoom ratio (magnification ratio) of 2.9 and an aperture ratio of about 3.0 to 5.0.

  FIG. 5 is a lens cross-sectional view at the wide-angle end of the zoom lens according to the second embodiment of the present invention. 6, 7, and 8 are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  The second embodiment is a zoom lens having a zoom ratio of 2.9 and an aperture ratio of about 2.9 to 5.0.

  FIG. 9 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. 10, 11 and 12 are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  The third exemplary embodiment is a zoom lens having a zoom ratio of 3.1 and an aperture ratio of about 2.9 to 5.0.

  FIG. 13 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 4 of the present invention. FIGS. 14, 15, and 16 are aberration diagrams of the zoom lens of Example 4 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  The fourth exemplary embodiment is a zoom lens having a zoom ratio of 3.5 and an aperture ratio of about 2.7 to 5.0.

  FIG. 17 is a lens cross-sectional view at the wide-angle end of the zoom lens according to Embodiment 5 of the present invention. 18, 19 and 20 are aberration diagrams of the zoom lens of Example 5 at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.

  Example 5 is a zoom lens having a zoom ratio of 3.1 and an aperture ratio of about 2.9 to 5.0.

  FIG. 21 is a schematic diagram of a main part of a digital still camera (imaging device) including the zoom lens of the present invention.

  The zoom lens of each embodiment is a photographic lens system used in an imaging apparatus. When the zoom lens of each embodiment is used as an imaging optical system for a video camera or a digital still camera, a subject image is formed on the imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD or CMOS sensor.

  In each lens cross-sectional view, the left is the subject (object) side (front), and the right 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 aperture stop, which is located on the object side of the second lens unit L2. G is a glass block corresponding to an optical filter, a face plate, etc., and IP is an image plane.

  The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end.

  In the aberration diagrams, d and g represent d-line, g-line, and ΔM and ΔS respectively represent a meridional image surface and a sagittal image surface. Lateral chromatic aberration is represented by the g-line. Fno is the F number, and ω is the half angle of view.

  In each embodiment, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit is positioned at both ends of the range in which the mechanism can move on the optical axis.

  The zoom lens of each embodiment includes, in order from the object side to the image side, a first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive refractive power, and a third lens unit L3 having a positive refractive power. . During zooming from the wide-angle end to the telephoto end, the first lens unit L1 moves along a locus that is convex toward the image side, the second lens unit L2 moves monotonically toward the object side, and the third lens unit L3 moves toward the image side. ing.

  The zoom lens of each embodiment performs main zooming by moving the second lens unit L2. The image plane variation accompanying zooming is corrected by the movement of the convex locus of the first lens unit L1 and the movement of the third lens unit L3 in the image side direction.

  Focusing from an infinitely distant object to a close object is performed by moving the third lens unit L3 to the object side.

  In each embodiment, the first lens unit L1 includes a positive eleventh lens G11, a negative twelfth lens G12, and a positive thirteenth lens G13 in order from the object side to the image side.

The radius of curvature of the object side surface of the eleventh lens G11 is R1, and the radius of curvature of the image side surface is R2. The imaging magnifications of the second lens unit L2 at the wide-angle end and the telephoto end are β2W and β2T, respectively. The imaging magnifications of the third lens group at the wide-angle end and the telephoto end are β3W and β3T, respectively. At this time,
0 <(R1-R2) / (R1 + R2) <5.5 (1)
2.55 <(β2T · β3W) / (β2W · β3T) <3.50 (2)
Is satisfied.

  When the lens shape of the eleventh lens G11 changes beyond the lower limit value of the conditional expression (1), the curvature of the image side surface of the twelfth lens G12 greatly changes accordingly. As a result, at the wide-angle end, flare due to downward light rays around the screen increases, and optical performance deteriorates.

  When the lens shape of the twelfth lens G12 changes beyond the upper limit value of the conditional expression (1), the curvature of the object side surface of the eleventh lens G11 becomes stronger with the concave surface facing the object side. For this reason, the entire lens system is enlarged, and spherical aberration on the short wavelength side is increased at the telephoto end, resulting in a decrease in optical performance.

  Conditional expression (2) is for maintaining good optical performance while ensuring a predetermined zoom ratio.

  If the upper limit value of conditional expression (2) is exceeded, the variable magnification sharing of the second lens unit L2 becomes too large, and it becomes difficult to ensure a predetermined zoom ratio. Further, it is not preferable because the number of lenses in each lens group must be increased to share aberrations, and the entire lens system becomes larger.

  When the lower limit value of conditional expression (2) is exceeded, the variable power sharing of the third lens unit L3 increases, and the amount of movement during zooming increases. For this reason, since the whole lens system becomes large, it is not preferable.

  By satisfying the above conditional expressions (1) and (2) at the same time, while maintaining a zoom magnification of about 2.8 to 4.0 times, various aberrations other than distortion are satisfactorily suppressed, and high performance and compactness are achieved. Realize a zoom lens.

  Distortion is corrected by known electronic processing when used in an imaging apparatus. By excluding correction of distortion, other aberrations are easily corrected.

  In each embodiment, conditional expressions (1) and (2) are preferably as follows in order to further reduce aberrations while further improving aberration correction.

0.05 <(R1-R2) / (R1 + R2) <5.2 (1a)
2.57 <(β2T · β3W) / (β2W · β3T) <3.20 (2a)
As described above, according to each embodiment, the entire system is configured by appropriately setting the lens configuration of the first lens unit L1 and the imaging magnifications at the wide-angle end and the telephoto end of the second and third lens units L2 and L3. The zoom lens has a wide angle of view with various aberrations corrected satisfactorily.

  In each embodiment, it is more preferable that one or more of the following conditions be satisfied.

  Let the focal lengths of the entire system at the wide-angle end and the telephoto end be fW and fT, respectively. Let the focal length of the first lens group be f1. Let the focal length of the second lens group be f2.

  Let D be the distance on the optical axis from the image side surface of the 23rd lens G23 to the object side surface of the 24th lens G24.

At this time,
−3.50 <f1 / fW <−2.40 (3)

0.10 <D / f2 <0.20 (5)
1.01 <β3T / β3W <1.30 (6)
It is preferable to satisfy one or more of the following conditions.

  Conditional expression (3) is for correcting coma and distortion with a good balance. Exceeding the upper limit value of conditional expression (3) is not good because large distortion will occur. If the lower limit of conditional expression (3) is exceeded, the occurrence of distortion will be reduced, but a large amount of coma will occur, which is not preferable.

  Conditional expression (4) is for keeping the entire system compact and maintaining good optical performance. If the upper limit of conditional expression (4) is exceeded and the focal length of the second lens unit L2 increases, the refractive power of the second lens unit L2 becomes loose, and each lens unit is secured in order to ensure a predetermined magnification (zoom ratio). It is necessary to increase the amount of movement during zooming. As a result, the entire system becomes large, which is not good.

  If the lower limit of conditional expression (4) is exceeded and the focal length of the second lens unit L2 becomes shorter, the power of the second lens unit L2 becomes stronger and the amount of movement for securing a predetermined zoom ratio decreases. This is advantageous for making the entire system compact. However, since the power of the second lens unit L2 becomes too strong, various aberrations such as astigmatism and coma increase, and correction of these becomes difficult.

  Conditional expression (5) is for keeping the entire system compact and maintaining good optical performance. If the upper limit of conditional expression (5) is exceeded and the distance on the optical axis between the 23rd lens G23 and the 24th lens G24 becomes longer, the second lens unit L2 becomes too thick, which is not good.

  Further, if the distance on the optical axis between the 23rd lens G23 and the 24th lens G24 becomes shorter than the upper limit value of the conditional expression (5), it becomes difficult to correct coma well at the wide angle end and the telephoto end. come.

  Conditional expression (6) relates to the image forming magnifications β3W and β3T of the third lens unit L3, and is intended to reduce the size of the entire system while ensuring a predetermined zoom ratio. When the upper limit value of conditional expression (6) is exceeded, the variable power sharing of the third lens unit L3 increases, and the amount of movement during zooming increases. For this reason, since the whole lens system becomes large, it is not preferable.

  When the lower limit of conditional expression (6) is exceeded, the variable magnification share of the third lens unit L3 decreases, and the variable magnification share of the second lens unit L2 increases accordingly, making it difficult to secure a predetermined zoom ratio. become. In addition, it is not good because the number of lenses in each lens group must be increased to share aberrations, and the lens system becomes larger.

  In each embodiment, it is preferable to set the numerical ranges of the conditional expressions (3) to (6) as follows in order to further reduce aberrations while further improving aberration correction.

  −3.30 <f1 / fW <−2.45 (3a)

0.102 <D / f2 <0.197 (5a)
1.02 <β3T / β3W <1.10 (6a)
Next, features of the lens configuration of each lens group will be described. The eleventh lens G11 has a convex surface on the image side, the twelfth lens G12 has a biconcave shape, and the thirteenth lens G13 has a convex surface on the object side and a meniscus shape.

  By configuring the first lens unit L1 in this way, in each embodiment, a zoom lens having excellent optical performance is realized without using an aspherical surface for the first lens unit L1 having the largest effective diameter.

  The first lens group has a role of imaging (incident) off-axis chief rays at the center of the stop (incidence pupil), and especially on the wide-angle side, the amount of refraction of off-axis chief rays is large, and various off-axis aberrations. In particular, astigmatism and distortion are likely to occur.

  Therefore, in each of the embodiments, like the normal wide-angle zoom lens, the lens shapes of the twelfth lens G12 and the thirteenth lens G13 that can suppress the increase in the lens diameter are specified, and the shape is used to suppress distortion aberration to some extent. An eleventh lens G11 is disposed.

  The surface shape of the twelfth lens G12 constituting the first lens unit L1 after the image side surface is such that the aperture stop SP and the optical axis intersect in order to suppress the occurrence of off-axis aberration caused by refraction of off-axis principal rays. The lens shape is close to a concentric sphere centered on the point to be corrected.

  In addition, the object-side surface shape of the twelfth lens G12 is mainly a lens shape with a concave surface facing the object side in order to suppress the occurrence of field curvature.

  In addition, by using materials with appropriate refractive indexes for the eleventh lens G11, the twelfth lens G12, and the thirteenth lens G13 and appropriately setting the lens interval, various aberrations other than distortion are suppressed.

  The second lens unit L2 includes, in order from the object side to the image side, a positive 21st lens G21, a positive 22nd lens G22, a negative 23rd lens G23, and a positive 24th lens G24.

  The 21st lens G21 and the 22nd lens G22 are both biconvex, and the 23rd lens G23 is biconcave. The 24th lens G24 has a convex surface on the object side.

  Each lens of the second lens unit L2 has a lens shape that reduces the refraction angle of the off-axis light beam emitted from the first lens unit L1 and does not cause off-axis aberrations.

  The twenty-first lens G21 is a lens with the highest height of the on-axis light beam, and is mainly involved in correcting spherical aberration and coma aberration.

  Next, the aberration generated in the 21st lens G21 and the 22nd lens G22 is corrected by changing the lens shape of the 23rd lens G23 cemented with the 22nd lens G22 to a lens shape having a concave surface on the image side surface. . Further, the coma aberration is favorably corrected by disposing the twenty-fourth lens G24 at a predetermined interval (D).

  The third lens unit L3 includes a biconvex single positive lens 31st lens G31. The third lens unit L3 acts as a field lens and maintains a good telecentricity.

  In each embodiment, the lens configuration of each lens is set as described above, so that a zoom lens suitable for a photographing optical system using a solid-state imaging device and having a small number of constituent lenses and particularly suitable for a retractable type is obtained. ing. In particular, it is possible to obtain a zoom lens having high optical performance, in which various aberrations other than distortion aberration with a zoom ratio of about 2.8 to 4.0 times are favorably corrected.

  Further, according to each embodiment, by appropriately setting the refractive power of the first lens unit L1 and the second lens unit L2, spherical aberration, various off-axis aberrations, in particular, field curvature, astigmatism, and coma aberration can be reduced. A zoom lens suitable for a large aperture ratio that can be corrected satisfactorily can be obtained.

  Note that the zoom lens of each of the above-described embodiments can be suitably used for an imaging apparatus that corrects distortion by image processing. In addition, it can be used in the same manner for a camera that does not care about distortion, such as a monitoring camera.

  As described above, according to each embodiment, the number of lenses suitable for an imaging apparatus using a solid-state imaging device is small, the entire system is compact, and high optical performance in which various aberrations other than distortion are corrected particularly well. A zoom lens having

  Next, numerical examples 1 to 5 corresponding to the first to fifth embodiments of the present invention will be described. In the numerical examples, i indicates the order of the surfaces from the object side, ri is the radius of curvature of the i-th lens surface (surface), and di is the lens thickness between the i-th surface and the (i + 1) -th surface. And air spacing, ndi, and νdi indicate the refractive index and Abbe number of the i-th member with respect to the d-line, respectively.

  The two surfaces closest to the image side are glass materials such as face plates. BF is the back focus in terms of air.

  Table 1 shows the relationship between the above-described conditional expressions and the respective examples.

Numerical example 1
Unit mm

Surface data surface number rd nd νd Effective diameter object surface ∞ ∞
1 = -279.045 1.50 1.772499 49.6 13.646
2 = -34.340 0.25 13.081
3 = -74.732 1.00 1.677900 55.3 11.845
4 = 6.513 2.47 9.285
5 = 7.423 1.80 1.846660 23.9 9.043
6 = 8.905 Variable 8.142
7 = Aperture 0.70 4.450
8 = 21.770 1.30 1.834807 42.7 4.628
9 = -61.844 0.15 4.650
10 = 6.239 2.15 1.806100 33.3 4.632
11 = -7.521 1.45 1.846660 23.9 4.115
12 = 4.633 2.29 3.466
13 = 16.084 1.20 1.806100 33.3 4.760
14 = -291.896 Variable 4.945
15 = 14.666 1.50 1.487490 70.2 6.891
16 = -41.513 Variable 6.855
17 = ∞ 0.80 1.516330 64.1 20.000
18 = ∞ 20.000

Various data zoom ratio 2.91520
Wide angle Medium telephoto focal length 5.65996 10.90317 16.49991
F number 2.98351 3.96090 5.00000
Angle of view 27.78289 15.29624 10.24439
Image height 2.982 2.982 2.982
Total lens length 38.82047 33.55435 35.38590
BF 4.90333 4.39066 3.87800
D6 17.95180 6.72701 2.59998
D14 3.11364 9.07224 15.03084
D16 3.87574 3.36307 2.850407

Entrance pupil position 10.95993 7.98033 3.87800
Exit pupil position -19.18286 -57.51110 -1256.9517
Front principal point position 15.28987 16.96305 22.35505
Rear principal point position -0.75663 -6.51251 -12.62191

Single lens Data lens Start surface Focal length
1 1 50.55562
2 3 -8.79391
3 5 33.82974
4 8 19.42538
5 10 4.54734
6 11 -3.21094
7 13 18.94339
8 15 22.42753

Zoom lens group data group Start surface Focal length Lens composition length Magnification Front principal point position Rear principal point position
1 1 -15.39750 7.01623 2.14437 -2.67091
2 7 11.86452 9.23881 -0.01761 -6.75530
3 15 22.42753 1.50000 0.26559 -0.75173

Numerical example 2
Unit mm

Surface data surface number rd nd νd Effective diameter object surface ∞ ∞
1 = 200.000 1.20 1.772499 49.6 12.507
2 = -135.000 0.50 11.849
3 = -500.000 1.00 1.677900 55.3 10.931
4 = 6.729 3.04 8.869
5 = 7.233 1.80 1.846660 23.9 8.339
6 = 8.036 Variable 7.359
7 = Aperture 0.70 4.715
8 = 19.176 1.30 1.834807 42.7 4.917
9 = -52.592 0.15 4.926
10 = 6.131 2.15 1.806100 33.3 4.882
11 = -7.981 1.60 1.846660 23.9 4.338
12 = 4.307 1.94 3.914
13 = 12.510 1.20 1.806100 33.3 4.935
14 = 44.116 Variable 5.066
15 = 15.522 1.50 1.487490 70.2 6.840
16 = -32.782 Variable 6.823
17 = ∞ 0.80 1.516330 64.1 20.000
18 = ∞ 20.000

Various data zoom ratio 2.91456
Wide angle Medium telephoto focal length 5.66 135 10.94315 16.50033
F number 2.86764 3.90738 5.00001
Angle of View 27.7771 15.24296 10.24413
Image height 2.982 2.982 2.982
Total lens length 37.5896 33.58067 35.93823
BF 4.656957 4.25696 3.85696
D6 16.58873 6.61120 3.00017
D14 2.91628 8.88488 14.85349
D16 3.62937 3.22967 2.82937

Entrance pupil position 10.61817 8.120124 6.60563
Exit pupil position -15.97879 -48.21963 -506.63566
Front principal point position 14.72635 16.78126 22.57263
Rear principal point position-1.0043923 -6.68619 -12.64337

Single lens Data lens Start surface Focal length
1 1 104.49599
2 3 -9.78613
3 5 42.15629
4 8 16.97293
5 10 4.61517
6 11 -3.11789
7 13 21.29964
8 15 21.83158

Zoom lens group data group Start surface Focal length Lens composition length Magnification Front principal point position Rear principal point position
1 1 -14.15522 7.54071 2.40602 -2.97099
2 7 11.24283 9.04387 -1.24802 -6.87097
3 15 21.83158 1.50000 0.32738 -0.69140

Numerical Example 3
Unit mm

Surface data surface number rd nd νd Effective diameter object surface ∞ ∞
1 = -29.738 1.30 1.772499 49.6 13.673
2 = -25.108 0.25 13.168
3 = -500.000 1.00 1.677900 55.3 11.444
4 = 6.574 2.20 9.182
5 = 7.441 1.80 1.846660 23.9 8.969
6 = 9.187 Variable 8.091
7 = Aperture 0.70 4.476
8 = 22.544 1.30 1.834807 42.7 4.668
9 = -48.495 0.15 4.704
10 = 6.018 2.15 1.806100 33.3 4.687
11 = -7.141 1.50 1.846660 23.9 4.166
12 = 4.393 2.03 3.755
13 = 13.925 1.20 1.806100 33.3 4.932
14 = 220.288 Variable 5.101
15 = 16.585 1.50 1.487490 70.2 6.966
16 = -26.541 Variable 6.955
17 = ∞ 0.80 1.516330 64.1 20.000
18 = ∞ 20.000

Various data zoom ratio 3.11298
Wide angle Medium telephoto focal length 5.300 319 10.79037 16.49978
F number 2.862001 3.91035 4.99999
Angle of view 29.36244 15.44854 10.24447
Image height 2.982 2.982 2.982
Total lens length 37.10449 31.93262 34.27915
BF 4.69492 4.39437 4.093829
D6 17.24052 5.94217 2.16222
D14 2.78321 8.90968 15.03616
D16 3.66733 3.36678 3.06624
Entrance pupil position 9.9 178 361 7.0 17039 5.283813
Exit pupil position -17.54598 -58.87674 956.26864
Front principal point position 13.955014 15.96720 22.06950
Rear principal point position -0.60540 -6.39599 -12.40594

Single lens Data lens Start surface Focal length
1 1 185.98617
2 3 -9.56454
3 6 31.39766
4 7 18.58985
5 9 4.37009
6 10 -3.03150
7 12 18.39230
21.17871

Zoom lens group data group Start surface Focal length Lens composition length Magnification Front principal point position Rear principal point position
1 1 -14.21347 6.54813 1.60054 -2.80940
2 7 11.26686 9.03264 -0.37636 -6.59383
3 15 21.17871 1.50000 0.39228 -0.62776

Numerical Example 4
Unit mm

Surface data surface number rd nd νd Effective diameter object surface ∞ ∞
1 = -64.114 1.50 1.772499 49.6 14.303
2 = -28.093 0.25 13.725
3 = -52.787 1.00 1.677900 55.3 12.122
4 = 6.501 2.21 9.405
5 = 7.528 1.80 1.846660 23.9 9.243
6 = 9.579 Variable 8.398
7 = Aperture 0.30 4.731
8 = 16.316 1.30 1.834807 42.7 4.852
9 = -185.199 0.15 4.849
10 = 6.157 2.15 1.806100 33.3 4.831
11 = -7.005 1.45 1.846660 23.9 4.323
12 = 4.366 2.02 3.538
13 = 13.810 1.20 1.806100 33.3 4.436
14 = -410.860 Variable 4.655
15 = 17.490 1.50 1.487490 70.2 7.144
16 = -20.456 Variable 7.132
17 = ∞ 0.80 1.516330 64.1 20.000
18 = ∞ 20.000

Various data zoom ratio 3.46148
Wide angle Medium telephoto focal length 5.20008 11.39808 17.99999
F number 2.65381 3.78910 5.00000
Angle of view 29.83221 14.66138 9.40657
Image height 2.982 2.982 2.982
Total lens length 37.06326 31.93265 35.22193
BF 4.701427 4.262659 3.82389
D6 17.54003 5.35824 1.59633
D14 2.69195 9.74314 16.79433
D16 3.67384 3.23507 2.79630
Entrance pupil position 10.22429 6.99241 5.15099
Exit pupil position -17.81586 -95.04054 123.22419
Front principal point position 14.22348 17.08216 25.86454
Rear principal point position -0.49866 -7.13536 -14.17610

Single lens Data lens Start surface Focal length
1 1 63.57695
2 3 -8.48110
3 5 29.60565
4 8 18.01527
5 10 4.38473
6 11 -3.00103
7 13 16.59524
8 15 19.59500

Zoom lens group data group Start surface Focal length Lens composition length Magnification Front principal point position Rear principal point position
1 1 -14.45691 6.76310 1.77118 -2.81471
2 7 11.29878 8.56818 -0.52038 -6.51283
3 15 19.59500 1.50000 0.47090 -0.55075

Numerical Example 5
Unit mm

Surface data surface number rd nd νd Effective diameter

Object ∞ ∞
1 = -85.461 D 1 = 1.80 1.772499 49.6 17.780
2 = -36.600 D 2 = 0.25 17.022
3 = -500.000 D 3 = 1.00 1.677900 55.3 14.203
4 = 6.671 D 4 = 3.53 10.566
5 = 7.676 D 5 = 1.80 1.846660 23.9 10.045
6 = 8.777 D 6 = Variable 9.060
7 = Aperture D 7 = 0.70 3.987
8 = 17.033 D 8 = 1.30 1.834807 42.7 4.149
9 = -106.282 D 9 = 0.15 4.142
10 = 6.079 D10 = 2.15 1.806 100 33.3 4.119
11 = -6.471 D11 = 1.45 1.846660 23.9 3.597
12 = 4.327 D12 = 1.18 2.970
13 = 17.560 D13 = 1.20 1.806100 33.3 3.497
14 = -71.644 D14 = variable 3.819
15 = 19.282 D15 = 1.80 1.487490 70.2 6.973
16 = -14.539 D16 = Variable 7.026
17 = ∞ D17 = 0.80 1.516330 64.1 20.000
18 = ∞ 20.000


Various data zoom ratio 3.08472
Wide angle Medium telephoto focal length 4.70072 9.49873 14.50042
F number 2.93015 3.94302 5.00001
Angle of View 32.38984 17.42899 11.62082
Image height 2.982 2.982 2.982
Total lens length 38.85923 31.70276 32.72078
BF 4.32358 4.07359 3.82359
D6 18.04184 5.68437 1.50139
D14 2.50394 7.70494 12.90594
D16 3.29600 3.04600 2.79600
Entrance pupil position 10.84921 7.82733 5.97208
Exit pupil position -16.01249 -59.37800 252.84313
Front principal point position 14.46335 15.90409 21.31686
Rear principal point position -0.377136 -5.42514 -10.67683
Single lens Data lens Start surface Focal length
1 1 81.55780
2 3 -9.70272
3 5 41.31794
4 8 17.67011
5 10 4.21035
6 11 -2.88495
7 13 17.60168
8 15 17.30517

Zoom lens group data group Start surface Focal length Lens composition length Magnification Front principal point position Rear principal point position
1 1 -14.86521 8.38204 1.97772 -3.96066
2 7 10.96697 8.13142 -0.94549 -5.83610
3 15 17.30517 1.80000 0.70215 -0.52942

  Next, an embodiment of a digital camera (optical apparatus) using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

  In FIG. 21, reference numeral 20 denotes a digital camera body, and 21 denotes a photographing optical system constituted by the zoom lenses of the first to fifth embodiments. Reference numeral 22 denotes an image sensor 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.

  In this way, by applying the zoom lens of the present invention to an optical device such as a digital camera, a small-sized imaging device having high optical performance is realized.

Lens sectional view of Example 1 Aberration diagram at the wide-angle end of Example 1 Aberration diagram at the intermediate zoom position in Example 1 Aberration diagram at telephoto end of Example 1 Lens sectional view of Example 2 Aberration diagrams at the wide-angle end of Example 2 Aberration diagram at the intermediate zoom position in Example 2 Aberration diagrams at the telephoto end of Example 2 Lens sectional view of Example 3 Aberration diagrams at the wide-angle end of Example 3 Aberration diagram at the intermediate zoom position in Example 3 Aberration diagrams at the telephoto end of Example 3 Lens sectional view of Example 4 Aberration diagrams at the wide-angle end of Example 4 Aberration diagrams at the intermediate zoom position of Example 4 Aberration diagrams at the telephoto end of Example 4 Lens sectional view of Example 5 Aberration diagrams at the wide-angle end of Example 5 Aberration diagrams at the intermediate zoom position of Example 5 Aberration diagrams at the telephoto end of Example 5 Schematic diagram of main parts of an imaging apparatus of the present invention

Explanation of symbols

L1 First lens group L2 Second lens group L3 Third lens group SP F-number determining member (aperture stop)
IP image plane G glass block d d line g g line ΔS sagittal image plane ΔM meridional image plane

Claims (12)

In order from the object side to the image side, the lens unit 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.
During zooming, in zoom lenses where the distance between each lens group changes,
The first lens group includes, in order from the object side to the image side, a positive eleventh lens, a negative twelfth lens, and a positive thirteenth lens. The radius of curvature of the object side surface of the eleventh lens is R1, The radius of curvature of the image side surface is R2, the imaging magnification of the second lens group at the wide-angle end and the telephoto end is β2W and β2T, respectively, and the imaging magnification of the third lens group at the wide-angle end and the telephoto end is β3W, respectively. When β3T is assumed,
0 <(R1-R2) / (R1 + R2) <5.5
2.55 <(β2T · β3W) / (β2W · β3T) <3.50
A zoom lens characterized by satisfying the following conditions:   During zooming from the wide-angle end to the telephoto end, the first lens group moves along a convex locus toward the image side, the second lens group moves monotonically toward the object side, and the third lens group monotonously toward the image side. The zoom lens according to claim 1, wherein the zoom lens moves to.   3. The zoom lens according to claim 1, wherein the twelfth lens has a biconcave shape, and the thirteenth lens has a meniscus shape with a convex surface on the object side. When the focal length of the entire system at the wide-angle end is fW and the focal length of the first lens group is f1,
−3.50 <f1 / fW <−2.40
The zoom lens according to claim 1, wherein the following condition is satisfied.   5. The second lens group includes a positive 21st lens, a positive 22nd lens, a negative 23rd lens, and a positive 24th lens in order from the object side to the image side. The zoom lens according to any one of the above.   6. The zoom lens according to claim 5, wherein both the twenty-first lens and the twenty-second lens have a biconvex shape, and the twenty-third lens has a biconcave shape. When the focal lengths of the entire system at the wide-angle end and the telephoto end are fW and fT, respectively, and the focal length of the second lens group is f2.

The zoom lens according to claim 1, wherein the following condition is satisfied. When the focal length of the second lens group is f2, and the distance on the optical axis from the image side surface of the 23rd lens to the object side surface of the 24th lens is D,
0.10 <D / f2 <0.20
The zoom lens according to claim 5, wherein the following condition is satisfied. The imaging magnifications β3W and β3T of the third lens group at the wide-angle end and the telephoto end are
1.01 <β3T / β3W <1.30
The zoom lens according to claim 1, wherein the following condition is satisfied.   10. The zoom lens according to claim 1, wherein the third lens unit moves toward the object side during focusing from an infinitely distant object to a close object. 10.   The zoom lens according to claim 1, wherein an image is formed on the photoelectric conversion element.   An image pickup apparatus comprising: the zoom lens according to claim 1; and a photoelectric conversion element that receives an image formed by the zoom lens.