JP2007093979A - Zoom lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact high-performance zoom lens whose angle of view in a wide angle end state exceeds 75°, and which has such a high variable power that a variable power ratio is ≥ about 4 and is suitable for a digital still camera or the like. <P>SOLUTION: The zoom lens is constituted of: 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 in order from an object side. When a focal distance is changed from the wide angle end state W to a telephoto end state T, the first to the fifth lens groups move respectively. The fourth lens group is constituted of: a positive lens component whose lens surface nearest to an image side is convex to the image side, and a negative lens component whose lens surface nearest to the image side is concave to the image side in order from the object side. The zoom lens satisfies a predetermined condition. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a zoom lens suitable for a video camera, a digital still camera, or the like using a solid-state imaging device.

  Today, digital still cameras and video cameras that use solid-state image sensors are becoming more and more integrated due to the increased integration of light receiving elements in recent years. High optical performance was required. In addition, there is a demand for a digital still camera that has a high zoom ratio and is small and excellent in portability for convenience of photographing.

  However, in a light receiving element with an increased number of pixels, there are problems that conventional optical systems cannot cope with optical performance over a wider light receiving area and that the lens system tends to be large due to the large aperture. As the lens system increases in size, the entire camera increases in size, resulting in inconvenience in portability.

  Digital still cameras, video cameras, and the like are generally equipped with zoom lenses. There have been an increasing number of zoom lenses having a high zoom ratio such that the zoom ratio (the focal length in the telephoto end state divided by the focal length in the wide-angle end state) is four times or more. A zoom lens having a high zoom ratio has the advantage that the focal length in the telephoto end state can be increased to photograph a subject at a long distance.

  On the other hand, these zoom lenses have the above-mentioned advantages particularly on the long focal point side, but there is a user need for shooting with a wider angle of view in order to expand the possibilities of the photographer's shooting expression. There is also a growing demand for zoom lenses having a wide field angle such that the angle of view in the end state exceeds 75 degrees. When the angle of view on the wide-angle side is wider, it is possible to widen the shooting expression of the photographer, such as shooting a wider range or getting closer to the subject to obtain a perspective effect.

In order to meet these demands, a zoom lens having an angle of view of about 70 degrees at the wide-angle end state and a zoom ratio of about 3.5 times or more, an angle of view of about 75 degrees at the wide-angle end state, Zoom lenses having a ratio of about 4 times have been proposed (see, for example, Patent Document 1 and Patent Document 2).
JP 2002-365547 A JP 2004-233750 A

  However, in the disclosed example of Patent Document 1, the angle of view in the wide-angle end state is about 70 degrees, and the zoom ratio is about 3.5, and it cannot be said that both the angle of view and the zoom ratio are sufficient.

  Further, in the disclosure example of Patent Document 2, the angle of view at the wide-angle end state is about 75 degrees and the zoom ratio is about 4. However, it is difficult to ensure telecentricity, and inconvenience such as shading occurs. It was not suitable for a digital still camera using a solid-state image sensor.

  As described above, it is extremely difficult to achieve both a high zoom ratio, a wide angle of view, and a high image quality, and there is a problem that the optical system becomes large even if both are compatible.

  The present invention has been made in view of the above problems, and has an angle of view exceeding 75 degrees at a wide-angle end state and a high zoom ratio of about 4 or more, and is suitable for a digital still camera or the like. The objective is to provide a compact and high-performance zoom lens.

  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, and a third lens having a positive refractive power. Group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and when the focal length changes from the wide-angle end state to the telephoto end state, the first lens group Moves with respect to the image plane, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group decreases, and the third lens group And the fourth lens group decreases, the distance between the fourth lens group and the fifth lens group increases, and the fourth lens group has the lens surface closest to the image side in order from the object side. A positive lens component with a convex surface on the image side and a negative lens component with a concave surface on the image side. Made is to provide a zoom lens which satisfies the following conditions.

11.0 <f1 / fw <21.0
−0.25 <f3 / f4 <−0.03
Where fw is the focal length of the entire lens system in the wide-angle end state, f1 is the focal length of the first lens group, f3 is the focal length of the third lens group, and f4 is the focal length of the fourth lens group. Represents.

  According to the present invention, there is provided a compact and high-performance zoom lens suitable for a digital still camera or the like, having a high zoom ratio with an angle of view exceeding 75 degrees at a wide-angle end state and a zoom ratio of about 4 or more. can do.

  The configuration of the zoom lens according to the embodiment of the present invention will be described below.

  The zoom lens according to the embodiment of the present invention 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 third lens having a positive refractive power. Group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. When the focal length changes from the wide-angle end state to the telephoto end state, the first lens group is The distance between the first lens group and the second lens group changes relative to the image plane, the distance between the second lens group and the third lens group decreases, and the third lens group and the fourth lens group The distance between the fourth lens group and the fifth lens group is increased, and the fourth lens group includes a positive lens component whose convex surface is convex from the object side to the image side. The lens surface closest to the image side is composed of a negative lens component having a concave shape on the image side.

  The fourth lens group includes a positive lens component and a negative lens component, and can satisfactorily correct spherical aberration and coma generated by the fourth lens group alone.

  With this configuration, it is possible to achieve a zoom lens having an excellent imaging performance with an angle of view exceeding 75 degrees at the wide-angle end state and a zoom ratio of about 4 times or more.

It is desirable that the zoom lens according to the embodiment of the present invention satisfies the following conditional expressions (1) and (2).
(1) 11.0 <f1 / fw <21.0
(2) -0.25 <f3 / f4 <-0.03
Here, fw is the focal length of the entire lens system in the wide-angle end state, f1 is the focal length of the first lens group, f3 is the focal length of the third lens group, and f4 is the fourth distance. This is the focal length of the lens group.

  Conditional expression (1) is a conditional expression for defining an optimum focal length range of the first lens group.

  When the upper limit of conditional expression (1) is exceeded, the refractive power of the first lens group becomes relatively weak, and the first lens group cannot effectively contribute to zooming, and the zoom ratio is It becomes impossible to secure a high zoom ratio of about 4 times or more. In addition, the amount of movement of the first lens group becomes large, and the variation in spherical aberration generated by the first lens group alone during zooming becomes large. As a result, performance degradation occurs in the entire zoom range from the wide-angle end state to the telephoto end state.

  If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens group becomes relatively strong, and the angle formed between the off-axis light beam incident on the first lens group and the optical axis at the wide angle side becomes smaller. If an angle of view exceeding 75 degrees in the wide-angle end state is reduced, the outer diameter of the first lens group is increased, which is contrary to the reduction in size. Further, since the refractive power of the first lens group becomes strong, the coma generated by the first lens group alone becomes too large, and the object of the present invention to obtain excellent optical performance cannot be achieved.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (1) to 20.0. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (1) to 19.0. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (1) to 12.0.

  Conditional expression (2) is a conditional expression for defining an optimum focal length ratio range of the third lens group and the fourth lens group.

  When the upper limit of conditional expression (2) is exceeded, the refractive power of the third lens group becomes relatively strong, and the variation of spherical aberration that occurs in the third lens group during zooming becomes large. Further, the refractive power of the fourth lens group becomes relatively weak, the amount of movement increases during zooming, and the fluctuation of coma generated in the fourth lens group becomes large. As a result, it becomes difficult to suppress degradation of performance in the entire zoom range from the wide-angle end state to the telephoto end state.

  If the lower limit of conditional expression (2) is not reached, the refractive power of the third lens group becomes relatively weak, making it difficult for the third lens group to efficiently contribute to zooming. A high zoom ratio of about 4 times or more cannot be secured. Further, since the refractive power of the fourth lens group becomes relatively strong, the coma aberration generated in the fourth lens group becomes too large, and the object of the present invention to obtain excellent optical performance cannot be achieved. End up.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (2) to −0.05. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (2) to −0.08. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (2) to −0.20. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (2) to −0.18.

  In the zoom lens according to the embodiment of the present invention, it is desirable that the negative lens component of the fourth lens group is a cemented lens of a positive lens having a convex surface facing the object side and a negative lens.

  The fourth lens group corrects the on-axis aberration generated by the fourth lens group alone, and has a single lens having a positive refractive power and a negative refractive power in order to make the exit pupil position as far as possible from the image plane. A cemented lens having a negative refractive power of a positive lens having a convex surface facing the image side, a positive lens having a convex surface facing the object side, and a negative lens having a concave surface facing the image side It is desirable. By reducing the off-axis light flux by the biconvex positive lens and keeping it away from the optical axis, the lens diameter can be reduced. In addition, since the fourth lens group as a whole has a large negative refractive power, it is possible to move the exit pupil position away from the image plane, which is suitable for an optical system using a solid-state imaging element as a light receiving element.

  In the zoom lens according to the embodiment of the present invention, the positive lens component of the fourth lens group is a biconvex positive lens, and the negative lens component is a negative meniscus lens having a convex surface facing the object side. desirable.

  The fourth lens group corrects the on-axis aberration generated by the fourth lens group alone, and has a single lens having a positive refractive power and a negative refractive power in order to make the exit pupil position as far as possible from the image plane. It is desirable that there be a biconvex positive lens and a negative meniscus lens having a convex surface facing the object side. By reducing the off-axis light flux by the biconvex positive lens and keeping it away from the optical axis, the lens diameter can be reduced. In addition, since the fourth lens group as a whole has a large negative refractive power, it is possible to move the exit pupil position away from the image plane, which is suitable for an optical system using a solid-state imaging element as a light receiving element.

In addition, it is desirable that the zoom lens according to the embodiment of the present invention satisfies the following conditional expression (3).
(3) 6.0 <f1 / (− f2) <10.0
Here, f2 is the focal length of the second lens group.

  Conditional expression (3) is a conditional expression for defining an appropriate range for the focal length ratio between the first lens group and the second lens group.

  When the upper limit of conditional expression (3) is exceeded, the refractive power of the first lens group becomes relatively weak, and the first lens group cannot effectively contribute to zooming, and the zoom ratio is It becomes impossible to secure a high zoom ratio of about 4 times or more. In addition, the amount of movement of the first lens group becomes large, and the fluctuation of coma generated in the first lens group during zooming becomes large. As a result, it becomes difficult to suppress a decrease in performance in the entire zoom range from the wide-angle end state to the telephoto end state. Alternatively, since the refractive power of the second lens group becomes relatively strong, the occurrence of off-axis aberrations such as coma and astigmatism cannot be suppressed, and high optical performance cannot be obtained.

  If the lower limit value of conditional expression (3) is not reached, the refractive power of the first lens group becomes relatively strong, and the angle formed between the off-axis ray incident on the first lens group and the optical axis on the wide-angle side is small. If an angle of view exceeding 75 degrees in the wide-angle end state is reduced, the outer diameter of the first lens group becomes large, which is contrary to the reduction in size. Or spherical aberration and coma aberration deteriorate and high optical performance cannot be obtained. Further, since the refractive power of the second lens group becomes relatively weak, the second lens group cannot effectively contribute to the zooming, and the zooming ratio is about 4 times or more. It will be impossible to secure.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (3) to 9.5. In order to further secure the effect of the present invention, it is more preferable to set the upper limit of conditional expression (3) to 9.0. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (3) to 6.5. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (3) to 7.0.

  In the zoom lens according to the embodiment of the present invention, when the focal length is changed from the wide-angle end state to the telephoto end state, the fifth lens group moves along the optical axis in the infinite focus state. It is desirable to move against. By moving the fifth lens group in this way, when zooming from the wide-angle end state to the telephoto end state, it is possible to effectively change the position of the off-axis ray passing through the fifth lens group. External aberrations can be corrected well over the entire zoom range.

  In the zoom lens according to the embodiment of the present invention, it is desirable to dispose at least one aspheric lens in the fourth lens group. By disposing an aspherical lens in the fourth lens group, it is possible to satisfactorily correct a variation in axial aberration that occurs in the fourth lens group alone.

  In the zoom lens according to the embodiment of the present invention, in order to improve performance, the third lens group includes, in order from the object side, a first partial lens group having a positive refractive power, an aperture stop, It is desirable that the second lens unit has a positive refractive power.

  In the zoom lens according to the embodiment of the present invention, in order to further improve the performance, the third lens group includes, in order from the object side, a meniscus negative lens having a convex surface directed toward the object side and an object side. A cemented lens having a positive refractive power (first partial lens group: positive partial lens group on the object side) composed of a positive lens having a convex surface, an aperture stop, a positive lens and an image with a convex surface facing the object side It is desirable that the lens is composed of a cemented lens (second partial lens group: image-side positive partial lens group) having a positive refractive power and composed of a meniscus negative lens having a convex surface facing the side.

  The first partial lens group needs to be corrected for spherical aberration and sine condition. The aberration can be corrected by a cemented lens having a positive refractive power, which is composed of a negative lens and a positive lens. In addition, the spherical aberration must be corrected in the entire third lens group to be in a predetermined off-axis aberration state. For this reason, the second partial lens group also needs to be corrected for spherical aberration. The second partial lens group is a cemented lens having a positive refracting power composed of two lenses, a positive lens and a negative lens, so that a decrease in performance can be minimized.

It is desirable that the zoom lens according to the embodiment of the present invention satisfies the following conditional expression (4).
(4) 1.6 <f3a / f3 <2.5
Here, f3 is the focal length of the third lens group.

  Conditional expression (4) defines an appropriate range for the focal length of the first partial lens group in the third lens group.

  When the upper limit value of conditional expression (4) is exceeded, the Petzval sum becomes positive and the diameter cannot be increased. Alternatively, the field curvature aberration is deteriorated and good imaging performance cannot be obtained.

  If the lower limit of conditional expression (4) is not reached, the Petzval sum becomes negatively large, making it difficult to obtain the desired Petzval sum. Alternatively, the field curvature aberration is deteriorated and good imaging performance cannot be obtained.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (4) to 2.3. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (4) to 1.7. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (4) to 1.8.

  In the zoom lens according to the embodiment of the present invention, it is desirable to perform focus adjustment from a long-distance object to a short-distance object by moving the fifth lens group to the object side. The fifth lens group adjusts the focus of the subject image formed by the first to fourth lens groups and controls the exit pupil position. In general, in a solid-state imaging device (CCD or the like), a microlens array is disposed immediately before the light receiving device in order to increase light receiving efficiency. For this reason, it is important for an optical system used in a digital still camera or the like to keep the exit pupil position away from the element surface. By moving the fifth lens group during zooming and focus adjustment, the position of the exit pupil can be corrected satisfactorily.

It is desirable that the zoom lens according to the embodiment of the present invention satisfies the following conditional expression (5).
(5) 3.8 <f5 / fw <6.0
Here, f5 is the focal length of the fifth lens group.

  Conditional expression (5) is a conditional expression for defining an appropriate focal length range of the fifth lens group.

  If the lower limit value of conditional expression (5) is not reached, the refractive power of the fifth lens group becomes strong, the coma aberration generated by the fifth lens group alone becomes too large, and the performance change during close-up shooting becomes large. It is not preferable. As a result, it becomes difficult to shorten the shortest shooting distance.

  When the upper limit value of conditional expression (5) is exceeded, the refractive power of the fifth lens group becomes weak, coma aberration and field curvature aberration are deteriorated, and good imaging performance cannot be obtained. Or the amount of movement at the time of focus adjustment becomes large, and the members of the drive system necessary for the movement increase in size, which may cause interference with other members. As a result, it becomes impossible to save space when storing in the camera body.

  In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (5) to 5.0. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (5) to 4.0. In order to further secure the effect of the present invention, it is more preferable to set the lower limit of conditional expression (5) to 4.1.

  In addition, the zoom lens according to the embodiment of the present invention preferably includes at least one aspheric lens in the second lens group in order to further improve the performance. By disposing an aspheric lens in the second lens group, it is possible to satisfactorily correct off-axis aberration fluctuations that occur when the focal length changes from the wide-angle end state to the telephoto end state.

  The zoom lens according to the embodiment of the present invention is a blur detection system that detects a blur of a lens system in order to prevent a shooting failure due to an image blur caused by a camera shake or the like that is likely to occur in a high-magnification zoom lens. And the driving means are combined with the lens system, and the whole or a part of one of the lens groups constituting the lens system is decentered as a shift lens group, thereby reducing the blur of the lens system detected by the blur detection system. It is possible to correct the image blur by driving the shift lens group by the driving unit and shifting the image so as to correct the resulting image blur (fluctuation of the image plane position). Thus, the zoom lens according to the embodiment of the present invention can function as a so-called vibration-proof optical system.

[Example]
Embodiments of the zoom lens according to the embodiment of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating a state of movement of each lens group in a refractive power distribution of a zoom lens according to each embodiment of the present invention and a change in a focal length state from a wide-angle end state W to a telephoto end state T.

  As shown in FIG. 1, the zoom lens according to each embodiment of the present invention 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, A filter group including a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, a fifth lens group G5 having a positive refractive power, a low-pass filter, an infrared cut filter, and the like. It consists of FL.

  When the focal length state changes from the wide-angle end state W to the telephoto end state T (ie, zooming), the first lens group G1 moves relative to the image plane I, and the first lens group G1 and the second lens group G2 are moved. The distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the fourth lens group G4 and the fourth lens group G4 The distance from the fifth lens group G5 increases, the first lens group G1, the third lens group G3, and the fourth lens group G4 move to the object side, and the second lens group G2 moves.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

In each of the following embodiments, the aspherical surface is defined as y in the direction perpendicular to the optical axis, and the distance (sag) along the optical axis from the tangential plane of the apex of each aspherical surface to each aspherical surface at height y. the amount) and S (y), of the reference spherical surface radius of curvature (paraxial radius of curvature) and r, a conic constant and kappa, when the n-th order aspherical coefficient was C _n, is expressed by the following formula .
S (y) = (y ² / r) / {1+ (1−κ × y ² / r ² ) ^1/2 }
+ C ₄ × y ⁴ + C ₆ × y ⁶ + C ₈ × y ⁸ + C ₁₀ × y ¹⁰
In each example, the second order aspherical coefficients C ₂ is zero. In each embodiment, an aspherical surface is marked with * on the left side of the surface number.

[First embodiment]
FIG. 2 is a diagram showing a lens configuration of the zoom lens according to the first example of the present invention.

  In FIG. 2, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface facing the image surface I in order from the object side and a positive meniscus lens having a convex surface facing the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image surface I, a biconcave negative lens L22, The lens includes a convex positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is a negative meniscus lens having a concave surface facing the image plane I side. The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. This is composed of a cemented positive lens L32.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image plane I side, a positive meniscus lens having a convex surface facing the object side, and the image plane I side. This is composed of a cemented negative lens L42 formed by bonding with a negative meniscus lens having a concave surface facing the surface.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

  Table 1 below lists values of specifications of the zoom lens according to the first example of the present invention. In Table 1, f is the focal length, and F.I. NO represents the F number, 2ω represents the angle of view (unit: degree), and Bf represents the back focus. Further, the surface number indicates the order of the lens surfaces from the object side along the direction in which the light beam travels, and the refractive index and Abbe number indicate values for the d-line (wavelength λ = 587.6 nm), respectively. In the radius of curvature, “∞” represents a plane, and the refractive index of air = 1.0000 is omitted.

  In addition, the focal length f, the radius of curvature, the surface interval, and other length units listed in all the following specification values are generally “mm”, but the optical system is proportionally enlarged or reduced. However, the same optical performance can be obtained, and the present invention is not limited to this. In the following embodiments, the same reference numerals are used and description thereof is omitted.

(Table 1)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 22.64 to 30.58
F.NO = 2.90 to 4.36 to 4.71
2ω = 87.34 to 27.67 to 20.81

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 115.3041 1.80 1.84666 23.78
2 66.6517 5.70 1.74100 52.64
3 306.1656 0.10
4 65.4023 3.65 1.81600 46.62
5 114.9566 (d5)
6 67.1379 1.35 1.80610 40.92
* 7 7.9900 5.83
8 -24.8678 1.90 1.77250 49.60
9 22.6103 1.50
10 24.0707 3.95 1.79504 28.54
11 -30.8527 0.47
12 -23.4091 1.67 1.72916 54.68
13 -27.4360 (d13)
14 27.0095 0.85 1.81600 46.62
15 14.6066 2.50 1.49782 82.52
16 -34.7176 0.90
17 ∞ 1.65 (Aperture stop S)
18 22.2124 2.50 1.49700 81.54
19 -13.4000 0.90 1.64000 60.08
20 -55.2064 (d20)
21 108.4995 3.00 1.58913 61.25
* 22 -23.4139 0.10
23 25.8317 2.80 1.67003 47.23
24 215.3189 0.80 1.79504 28.54
25 11.3488 (d25)
26 27.8547 2.98 1.60300 65.44
27 -50.0000 (d27)
28 ∞ 1.72 1.54437 70.51
29 ∞ 0.96
30 ∞ 0.50 1.48749 70.23
31 ∞ (Bf)

(Aspheric data)
The lens surfaces of the seventh surface and the twenty-second surface are aspherical.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
7.9900 -0.0453 + 1.7188 × 10 ^-4 + 1.5706 × 10 ^-6 -1.7649 × 10 ^-8 + 4.1787 × 10 ^-10
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-23.4139 -4.6412 + 9.5213 × 10 ^-6 -1.9843 × 10 ^-7 + 1.0328 × 10 ^-8 -1.2384 × 10 ^-10

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d25 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d27 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3861 22.6419 30.5832
d5 2.8000 37.3984 46.9517
d13 25.8994 4.5866 2.3000
d20 6.5000 3.7409 3.2679
d25 5.0000 21.0234 24.7657
d27 3.8435 4.0541 3.8560
Bf 0.9978 0.9974 0.9971

(Values for conditional expressions)
fw = 6.3861
f1 = 112.7388
f2 = -13.0346
f3 = 2.9038
f3a = 44.1237
f4 = -230.0038
f5 = 30.0998
(1) f1 / fw = 17.6539
(2) f3 / f4 = -0.0996
(3) f1 / (− f2) = 8.6492
(4) f3a / f3 = 1.9265
(5) f5 / fw = 4.7134

  FIG. 3 shows various aberration diagrams in the infinitely focused state with respect to the d-line (λ = 587.6 nm) of the zoom lens according to the first example, and (a) is a wide-angle end state (f = 6.39 mm). (B) is the various aberrations in the intermediate focal length state (f = 22.24 mm), (c) is the various aberration diagrams in the telephoto end state (f = 30.58 mm).

  In each aberration diagram, FNO represents an F number, Y represents an image height, and A represents a half field angle (unit: degree) with respect to each image height. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Further, in the spherical aberration diagram, the solid line indicates spherical aberration, and the broken line indicates sine condition (sine condition). In the following embodiments, the same reference numerals are used and description thereof is omitted.

  As is apparent from each aberration diagram, in the zoom lens according to the first example, various aberrations are favorably corrected in each focal length state from the wide-angle end state W to the telephoto end state T, and excellent imaging performance is obtained. You can see that

[Second Embodiment]
FIG. 4 is a diagram showing a lens configuration of a zoom lens according to the second example of the present invention.

  In FIG. 4, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface directed toward the image plane I and a positive meniscus lens having a convex surface directed toward the object side in order from the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image surface I, a biconcave negative lens L22, The lens includes a convex positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is a negative meniscus lens having a concave surface facing the image plane I side. The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. This is composed of a cemented positive lens L32.

  The fourth lens group G4 is composed of, in order from the object side, a cemented combination of a biconvex positive lens L41 having both aspheric surfaces and a biconvex positive lens and a biconcave negative lens. It is composed of a negative lens L42.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

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

(Table 2)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 20.00 to 30.58
F.NO = 2.84 to 4.21 to 4.73
2ω = 87.34 to 31.10 to 20.81

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 100.0000 1.80 2.00330 28.27
2 50.6447 5.78 1.72000 50.23
3 369.4922 0.10
4 57.3854 3.65 1.81600 46.62
5 132.7268 (d5)
6 86.6654 1.35 1.80610 40.92
* 7 7.9900 6.00
8 -26.1669 1.55 1.77250 49.60
9 20.7754 1.50
10 22.4713 4.50 1.79504 28.54
11 -24.7127 0.21
12 -24.4759 1.90 1.83481 42.71
13 -40.0000 (d13)
14 28.5591 0.85 1.81600 46.62
15 15.0006 2.50 1.49782 82.52
16 -34.6231 0.90
17 ∞ 1.65 (Aperture stop S)
18 17.9481 2.66 1.49700 81.54
19 -13.4000 0.90 1.64000 60.08
20 -59.9640 (d20)
* 21 49.8866 3.00 1.58913 61.25
* 22 -28.7830 0.10
23 200.0000 2.80 1.72342 37.95
24 -42.4035 0.80 1.79504 28.54
25 17.5173 (d25)
26 29.3474 2.70 1.60300 65.44
27 -64.0827 (d27)
28 ∞ 1.72 1.54437 70.51
29 ∞ 0.96
30 ∞ 0.50 1.51633 64.14
31 ∞ (Bf)

(Aspheric data)
The lens surfaces of the seventh surface, the twenty-first surface, and the twenty-second surface are formed in an aspherical shape.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
7.9900 +0.1181 + 1.3222 × 10 ^-4 + 1.9635 × 10 ^-6 -2.7973 × 10 ^-8 + 5.4812 × 10 ^-10
[21st page]
r κ C ₄ C ₆ C ₈ C ₁₀
49.8866 +10.587 + 1.3214 × 10 ^-4 + 4.8651 × 10 ^-6 -7.9690 × 10 ^-8 + 2.1788 × 10 ^-9
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-28.7830 -8.8421 + 1.9421 × 10 ^-4 + 6.2619 × 10 ^-6 -1.2153 × 10 ^-7 + 3.9732 × 10 ^-9

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d25 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d27 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3860 19.9987 30.5795
d5 2.8000 25.5925 37.6762
d13 25.7898 5.8029 2.6243
d20 6.5000 3.5435 2.7715
d25 5.0000 21.1541 26.6508
d27 3.8435 4.0541 3.8560
Bf 0.9968 0.9972 0.9976

(Values for conditional expressions)
fw = 6.3860
f1 = 93.7532
f2 = -12.0582
f3 = 21.3385
f3a = 46.1950
f4 = −140.0004
f5 = 33.74837
(1) f1 / fw = 14.66811
(2) f3 / f4 = -0.1524
(3) f1 / (− f2) = 7.7751
(4) f3a / f3 = 2.1649
(5) f5 / fw = 5.2847

  FIG. 5 is a diagram showing various aberrations with respect to the d-line (λ = 587.6 nm) in the infinitely focused state of the zoom lens according to the second example, and (a) is a wide-angle end state (f = 6.39 mm). (B) is the various aberrations in the intermediate focal length state (f = 20.00 mm), (c) is the various aberration diagrams in the telephoto end state (f = 30.58 mm).

  As is apparent from each aberration diagram, in the zoom lens according to the second example, various aberrations are satisfactorily corrected in each focal length state from the wide-angle end state W to the telephoto end state T, and excellent imaging performance is obtained. You can see that

[Third embodiment]
FIG. 6 is a diagram showing a lens configuration of a zoom lens according to Example 3 of the present invention.

  In FIG. 6, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface toward the image plane I and a positive meniscus lens having a convex surface toward the object side in order from the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image surface I, a biconcave negative lens L22, The lens includes a convex positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is a negative meniscus lens having a concave surface facing the image plane I side. The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. This is composed of a cemented positive lens L32.

  The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 having an aspheric surface on the image surface I side, a positive meniscus lens having a convex surface on the object side, and a concave surface on the image surface I side. This is composed of a cemented negative lens L42 formed by bonding with a directed negative meniscus lens.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

  Table 3 below lists values of specifications of the zoom lens according to the third example of the present invention.

(Table 3)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 22.64 to 30.58
F.NO = 2.88 to 4.34 to 4.68
2ω = 87.30 to 27.72 to 20.83

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 100.7400 1.80 1.84666 23.78
2 60.2742 5.70 1.74100 52.64
3 201.8558 0.10
4 64.9767 3.65 1.81600 46.62
5 123.6087 (d5)
6 74.7594 1.35 1.80610 40.92
* 7 7.9900 6.00
8 -26.9973 1.72 1.77250 49.60
9 21.7351 1.50
10 23.4892 4.12 1.79504 28.54
11 -30.1775 0.87
12 -19.7462 1.20 1.72916 54.68
13 -23.4040 (d13)
14 28.1860 0.85 1.81600 46.62
15 14.6915 2.50 1.49782 82.52
16 -33.1873 0.90
17 ∞ 1.65 (Aperture stop S)
18 21.7367 2.50 1.49700 81.54
19 -13.4000 0.90 1.64000 60.08
20 -51.2539 (d20)
21 -1087.3153 3.00 1.58913 61.25
* 22 -22.2818 0.10
23 21.2689 2.80 1.67003 47.23
24 180.5626 0.80 1.79504 28.54
25 10.9884 (d25)
26 27.7230 2.96 1.60300 65.44
27 -50.0000 (d27)
28 ∞ 1.72 1.54437 70.51
29 ∞ 0.96
30 ∞ 0.50 1.51633 64.14
31 ∞ (Bf)

(Aspheric data)
The lens surfaces of the seventh surface and the twenty-second surface are aspherical.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
7.9900 -0.2733 + 2.2077 × 10 ^-4 + 1.1423 × 10 ^-6 -1.2656 × 10 ^-8 + 3.0656 × 10 ^-10
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-22.2818 -3.6606 + 4.7031 × 10 ^-6 -2.6714 × 10 ^-7 + 1.2770 × 10 ^-8 -1.6765 × 10 ^-10

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d25 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d27 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3860 22.6388 30.5830
d5 2.8000 36.6706 46.1803
d13 25.6986 4.5450 2.3000
d20 6.5000 3.4368 3.0983
d25 5.0000 21.2760 24.7122
d27 3.8435 4.0541 3.8560
Bf 0.9979 0.9979 0.9979

(Values for conditional expressions)
fw = 6.3860
f1 = 110.0837
f2 = -12.9605
f3 = 22.4896
f3a = 45.0578
f4 = −185.0055
f5 = 30.0068
(1) f1 / fw = 17.2383
(2) f3 / f4 = -0.1216
(3) f1 / (− f2) = 8.4938
(4) f3a / f3 = 2.0035
(5) f5 / fw = 4.6988

  FIG. 7 is a diagram showing various aberrations with respect to the d-line (λ = 587.6 nm) in the infinitely focused state of the zoom lens according to the third example, and (a) is a wide-angle end state (f = 6.39 mm). (B) is the various aberrations in the intermediate focal length state (f = 22.24 mm), (c) is the various aberration diagrams in the telephoto end state (f = 30.58 mm).

  As is apparent from each aberration diagram, in the zoom lens according to the third example, various aberrations are satisfactorily corrected in each focal length state from the wide-angle end state W to the telephoto end state T, and excellent imaging performance is obtained. You can see that

[Fourth embodiment]
FIG. 8 is a diagram showing a lens configuration of a zoom lens according to Example 4 of the present invention.

  In FIG. 8, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface toward the image plane I and a positive meniscus lens having a convex surface toward the object side in order from the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image surface I, a biconcave negative lens L22, The lens includes a convex positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is a negative meniscus lens having a concave surface facing the image plane I side. The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. This is composed of a cemented positive lens L32.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image surface I side, and a negative meniscus lens L42 having a concave surface facing the image side. Yes.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

  Table 4 below provides values of specifications of the zoom lens according to the fourth example of the present invention.

(Table 4)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 20.36 to 30.58
F.NO = 2.85 to 4.17 to 4.57
2ω = 87.37 to 30.49 to 20.81

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 100.0000 1.80 2.00330 28.27
2 53.2650 6.25 1.75500 52.32
3 459.8382 0.10
4 58.6540 3.65 1.81600 46.62
5 119.4293 (d5)
6 224.2639 1.35 1.80610 40.92
* 7 7.9900 5.65
8 -29.9375 1.55 1.78800 47.37
9 23.9838 1.50
10 24.5467 4.50 1.79504 28.54
11 -22.5043 0.10
12 -23.6560 1.90 1.76200 40.10
13 -40.0000 (d13)
14 27.3033 0.85 1.81600 46.62
15 14.4404 2.55 1.49782 82.52
16 -31.9614 0.90
17 ∞ 1.65 (Aperture stop S)
18 22.5893 2.55 1.49700 81.54
19 -13.4000 0.90 1.64000 60.08
20 -53.7608 (d20)
21 21.1294 3.00 1.58913 61.25
* 22 -37.6181 0.20 1.00000
23 37.3575 1.90 1.79504 28.54
24 9.9019 (d24)
25 23.8921 3.25 1.60300 65.44
26 -50.0000 (d26)
27 ∞ 1.72 1.54437 70.51
28 ∞ 0.96
29 ∞ 0.50 1.51633 64.14
30 ∞ (Bf)

(Aspheric data)
The lens surfaces of the seventh surface and the twenty-second surface are aspherical.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
7.9900 +0.6986 -5.5400 × 10 ^-7 -7.8138 × 10 ^-7 + 1.3265 × 10 ^-8 -1.3639 × 10 ^-10
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-37.6181 -8.1796 + 3.2471 × 10 ^-5 -3.2265 × 10 ^-7 + 8.7591 × 10 ^-9 -1.4214 × 10 ^-10

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d24 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d26 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3860 20.3609 30.5829
d5 2.8000 27.7759 38.6913
d13 26.3901 5.9658 2.7397
d20 6.5000 3.0241 2.1520
d24 5.1924 21.1074 25.9107
d26 3.8435 4.0541 3.8560
Bf 0.9981 0.9980 0.9980

(Values for conditional expressions)
fw = 6.3860
f1 = 91.4698
f2 = -13.1219
f3 = 22.6285
f3a = 42.9146
f4 = -136.0000
f5 = 27.2617
(1) f1 / fw = 14.3235
(2) f3 / f4 = -0.1664
(3) f1 / (− f2) = 6.9708
(4) f3a / f3 = 1.8965
(5) f5 / fw = 4.2690

  FIG. 9 is a diagram illustrating various aberrations with respect to the d-line (λ = 587.6 nm) in the infinitely focused state of the zoom lens according to the fourth example, and (a) is a wide-angle end state (f = 6.39 mm). (B) is the various aberrations in the intermediate focal length state (f = 20.36 mm), (c) is the various aberration diagrams in the telephoto end state (f = 30.58 mm).

  As is apparent from each aberration diagram, in the zoom lens according to the fourth example, various aberrations are well corrected in each focal length state from the wide-angle end state W to the telephoto end state T, and excellent imaging performance is obtained. You can see that

[Fifth embodiment]
FIG. 10 is a diagram showing a lens configuration of a zoom lens according to Example 5 of the present invention.

  In FIG. 10, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface facing the image plane I and a positive meniscus lens having a convex surface facing the object side in order from the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image surface I, a biconcave negative lens L22, The lens includes a convex positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a is a negative meniscus lens having a concave surface facing the image plane I side. The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. This is composed of a cemented positive lens L32.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image surface I side, and a negative meniscus lens L42 with a concave surface facing the image surface I. Has been.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

  Table 5 below provides values of specifications of the zoom lens according to the fifth example of the present invention.

(Table 5)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 22.91 to 30.58
F.NO = 2.92 to 4.45 to 4.76
2ω = 87.35 to 27.46 to 20.92

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 93.7929 1.80 2.00330 28.27
2 51.1044 6.38 1.77250 49.60
3 261.5657 0.10
4 60.4549 3.65 1.81600 46.62
5 119.1208 (d5)
6 127.3830 1.35 1.80610 40.92
* 7 7.9900 6.00
8 -30.8890 1.55 1.78800 47.37
9 24.0817 1.50
10 24.3759 4.48 1.79504 28.54
11 -23.3387 0.10
12 -23.6596 1.89 1.76200 40.10
13 -40.0000 (d13)
14 27.5131 0.85 1.81600 46.62
15 14.4815 2.50 1.49782 82.52
16 -32.3872 0.90
17 ∞ 1.65 (Aperture stop S)
18 21.9181 2.50 1.49700 81.54
19 -13.4000 0.90 1.64000 60.08
20 -52.9108 (d20)
21 20.9906 3.00 1.58913 61.25
* 22 -36.1792 0.21
23 38.5842 2.00 1.79504 28.54
24 9.8325 (d24)
25 25.5535 3.14 1.60300 65.44
26 -50.0000 (d26)
27 ∞ 1.72 1.54437 70.51
28 ∞ 0.96
29 ∞ 0.50 1.51633 64.14
30 ∞ (Bf)

(Aspheric data)
The lens surfaces of the seventh surface and the twenty-second surface are aspherical.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
7.9900 +0.6626 + 7.0876 × 10 ^-6 -3.7928 × 10 ^-7 + 6.4108 × 10 ^-9 -3.1650 × 10 ^-11
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-36.1792 -4.0180 + 4.8429 × 10 ^-5 -3.8646 × 10 ^-7 + 1.1077 × 10 ^-8 -2.1126 × 10 ^-10

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d24 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d26 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3860 22.9055 30.5830
d5 2.8000 32.4974 40.9695
d13 26.8094 4.4796 2.3000
d20 6.5000 2.7656 2.1760
d24 5.2090 22.3645 25.7635
d26 3.5535 3.7641 3.5660
Bf 0.9980 0.9979 0.9979

(Values for conditional expressions)
fw = 6.3860
f1 = 99.7618
f2 = -13.3432
f3 = 22.3995
f3a = 45.5833
f4 = −136.0005
f5 = 28.4898
(1) f1 / fw = 15.6219
(2) f3 / f4 = -0.1647
(3) f1 / (− f2) = 7.4766
(4) f3a / f3 = 2.0350
(5) f5 / fw = 4.4613

  FIG. 11 is a diagram illustrating various aberrations with respect to the d-line (λ = 587.6 nm) in the infinitely focused state of the zoom lens according to the fifth example, and (a) is a wide-angle end state (f = 6.39 mm). (B) is the various aberrations in the intermediate focal length state (f = 22.91 mm), (c) is the various aberration diagrams in the telephoto end state (f = 30.58 mm).

  As is apparent from each aberration diagram, in the fifth example, it is understood that various aberrations are well corrected in each focal length state from the wide-angle end state W to the telephoto end state T, and excellent imaging performance is obtained.

[Sixth embodiment]
FIG. 12 is a diagram showing a lens configuration of a zoom lens according to Example 6 of the present invention.

  In FIG. 12, the first lens group G1 includes a cemented positive lens L11 formed by bonding a negative meniscus lens having a concave surface directed toward the image plane I and a positive meniscus lens having a convex surface directed toward the object side in order from the object side. It is composed of a positive meniscus lens L12 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 an aspheric surface on the image plane I side and a concave surface facing the image side, a negative biconcave lens L22, and a biconvex shape. Positive lens L23 and a negative meniscus lens L24 having a concave surface facing the object side.

  The third lens group G3 includes, in order from the object side, a first partial lens group G3a and a second partial lens group G3b. The first partial lens group G3a includes a negative meniscus lens having a concave surface facing the image side and both The second partial lens group G3b is composed of a biconvex positive lens and a negative meniscus lens having a concave surface facing the object side. It is composed of a cemented positive lens L32.

  The fourth lens group G4 includes, in order from the object side, a biconvex positive lens L41 having an aspheric surface on the image surface I side, and a negative meniscus lens L42 with a concave surface facing the image surface I. Has been.

  The fifth lens group G5 is composed of a biconvex positive lens L51.

  Further, the filter group FL includes a low-pass filter, an infrared cut filter, and the like. The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  Further, the focus adjustment from the long distance object to the short distance object is performed by moving the fifth lens group G5 in the object direction.

  The aperture stop S is disposed between the first partial lens group G3a and the second partial lens group G3b, and moves together with the third lens group G3 during zooming from the wide-angle end state W to the telephoto end state T. To do.

  Table 6 below provides values of specifications of the zoom lens according to the sixth example of the present invention.

(Table 6)
(Overall specifications)
Wide-angle end state Intermediate focal length state Telephoto end state
f = 6.39 to 23.00 to 30.58
F.NO = 2.93 to 4.41 to 4.73
2ω = 87.36 to 27.42 to 20.98

(Lens data)
Surface number Curvature radius Surface spacing Refractive index Abbe number
1 100.0000 1.80 2.00330 28.27
2 51.9449 6.34 1.75500 52.32
3 274.6159 0.10
4 61.0541 3.65 1.83400 37.16
5 120.4243 (d5)
6 112.6075 1.35 1.80610 40.92
* 7 8.0070 5.85
8 -26.5756 1.38 1.75500 52.32
9 25.5186 1.45
10 26.1672 4.41 1.85026 32.35
11 -22.9852 0.33
12 -25.2608 0.90 1.72916 54.68
13 -48.4171 (d13)
14 26.6008 0.85 1.79952 42.22
15 14.1701 2.50 1.49782 82.52
16 -33.6615 0.90
17 ∞ 1.65 (Aperture stop S)
18 21.4502 2.50 1.49700 81.54
19 -13.4000 0.95 1.64000 60.08
20 -52.6505 (d20)
21 23.5219 3.00 1.58913 61.25
* 22 -42.9685 0.22
23 28.3564 1.56 1.79504 28.54
24 9.8447 (d24)
25 26.3540 2.96 1.60300 65.44
26 -53.8824 (d26)
27 ∞ 1.72 1.54437 70.51
28 ∞ 0.96 1.00000
29 ∞ 0.50 1.51633 64.14
30 ∞ (Bf)

(Aspherical data)
The lens surfaces of the seventh surface and the twenty-second surface are aspherical.
[Seventh side]
r κ C ₄ C ₆ C ₈ C ₁₀
8.0070 +0.6509 + 1.2676 × 10 ^-5 -3.1119 × 10 ^-7 + 5.6387 × 10 ^-9 -9.2088 × 10 ^-12
[22nd page]
r κ C ₄ C ₆ C ₈ C ₁₀
-42.9685 -3.4427 + 4.6025 × 10 ^-5 -5.6461 × 10 ^-7 + 2.4225 × 10 ^-8 -4.6826 × 10 ^-10

(Variable interval data)
The axial air gap d5 between the first lens group G1 and the second lens group G2, the axial air gap d13 between the second lens group G2 and the third lens group G3, the third lens group G3 and the fourth lens group G4, The on-axis air distance d20, the on-axis air distance d24 between the fourth lens group G4 and the fifth lens group G5, the on-axis air distance d26 between the fifth lens group G5 and the low pass filter FL, and the back focus Bf are: It changes during zooming.

Wide-angle end state Intermediate focal length state Telephoto end state
f 6.3861 23.0003 30.5832
d5 2.8000 34.2417 43.1928
d13 28.6733 4.5794 2.3000
d20 6.5000 2.8748 2.1331
d24 5.1146 21.8299 25.3887
d26 3.5535 3.7641 3.5660
Bf 0.9931 0.9934 0.9935

(Values for conditional expressions)
fw = 6.3861
f1 = 106.5376
f2 = -14.1084
f3 = 21.9680
f3a = 42.6939
f4 = −140.0018
f5 = 29.7630
(1) f1 / fw = 16.6826
(2) f3 / f4 = -0.1569
(3) f1 / (− f2) = 7.5513
(4) f3a / f3 = 1.9435
(5) f5 / fw = 4.6606

  FIG. 13 is a diagram showing various aberrations with respect to the d-line (λ = 587.6 nm) in the infinitely focused state of the zoom lens according to Example 6 of the present invention, where (a) is a wide-angle end state (f = 6. (B) shows various aberrations in the intermediate focal length state (f = 23.00 mm), and (c) shows various aberrations in the telephoto end state (f = 30.58 mm). .

  As is apparent from each aberration diagram, the zoom lens according to the sixth example has excellent imaging performance with various aberrations corrected well in each focal length state from the wide-angle end state W to the telephoto end state T. I understand that.

  As described above, according to the present invention, it is possible to realize a small and high-performance zoom lens having a high zoom ratio and a field angle at the wide-angle end exceeding 75 degrees.

  As an embodiment of the present invention, a lens system having a five-group configuration is shown. However, a lens system having a six-group configuration including the five groups and a lens system having a group configuration of more than five groups is 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. Moreover, 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.

FIG. 6 shows how the lens groups move when the refractive power distribution of the zoom lens according to each embodiment of the present invention and the change in the focal length state from the wide-angle end state W to the telephoto end state T are shown. 1 is a cross-sectional view showing a lens configuration of a zoom lens according to a first example of the present invention. FIG. 4A shows various aberration diagrams for the d-line (wavelength λ = 587.6 nm) of the zoom lens according to Example 1 of the present invention, and FIG. 5A is a diagram showing various aberrations in the wide-angle end state (f = 6.39 mm); (B) shows various aberrations in the intermediate focal length state (f = 22.64 mm), and (c) shows various aberrations in the telephoto end state (f = 30.58 mm). Sectional drawing which shows the lens structure of the zoom lens concerning 2nd Example of this invention. FIG. 7A shows various aberration diagrams for the d-line (λ = 587.6 nm) of the zoom lens according to Example 2 of the present invention, and FIG. 9A shows various aberration diagrams in the wide-angle end state (f = 6.39 mm); b) Various aberrations in the intermediate focal length state (f = 20.00 mm), and (c) are various aberration diagrams in the telephoto end state (f = 30.58 mm). Sectional drawing which shows the lens structure of the zoom lens concerning 3rd Example of this invention. FIG. 9A shows various aberration diagrams for the d-line (λ = 587.6 nm) of the zoom lens according to Example 3 of the present invention, and FIG. 10A shows various aberration diagrams in the wide-angle end state (f = 6.39 mm); b) Various aberrations in the intermediate focal length state (f = 22.64 mm), and (c) are various aberration diagrams in the telephoto end state (f = 30.58 mm). Sectional drawing which shows the lens structure of the zoom lens concerning 4th Example of this invention. FIG. 7A shows various aberration diagrams for the d-line (λ = 587.6 nm) of the zoom lens according to Example 4 of the present invention, and FIG. b) Various aberrations in the intermediate focal length state (f = 20.36 mm), and (c) are various aberration diagrams in the telephoto end state (f = 30.58 mm). Sectional drawing which shows the lens structure of the zoom lens concerning 5th Example of this invention. FIG. 9A shows various aberration diagrams for the d-line (λ = 587.6 nm) of the zoom lens according to Example 5 of the present invention, and FIG. b) shows various aberrations in the intermediate focal length state (f = 22.91 mm), and (c) shows various aberrations in the telephoto end state (f = 30.58 mm). Sectional drawing which shows the lens structure of the zoom lens concerning 6th Example of this invention. FIG. 9A shows various aberration diagrams for the d-line (λ = 587.6 nm) of the zoom lens according to Example 6 of the present invention, and FIG. b) shows various aberrations in the intermediate focal length state (f = 23.00 mm), and (c) shows various aberrations in the telephoto end state (f = 30.58 mm).

Explanation of symbols

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G3a 1st partial lens group G3b 2nd partial lens group S Aperture stop FL filter group I Image surface

Claims (12)

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 having a negative refractive power And a fifth lens group having positive refractive power,
When the focal length changes from the wide-angle end state to the telephoto end state, the first lens group moves with respect to the image plane, the distance between the first lens group and the second lens group changes, and the first lens group changes. 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 decreases, and the distance between the fourth lens group and the fifth lens group increases. And
The fourth lens group includes, in order from the object side, a positive lens component having a convex surface facing the image side, and a negative lens component having a concave surface facing the image side.
A zoom lens satisfying the following conditions:
11.0 <f1 / fw <21.0
−0.25 <f3 / f4 <−0.03
However,
fw: focal length of the entire lens system in the wide angle end state f1: focal length of the first lens group f3: focal length of the third lens group f4: focal length of the fourth lens group The zoom lens according to claim 1.
The zoom lens according to claim 1, wherein the negative lens component is a cemented lens of a positive lens having a convex surface facing the object side and a negative lens. The zoom lens according to claim 1.
The zoom lens according to claim 1, wherein the positive lens component is a biconvex positive lens, and the negative lens component is a negative meniscus lens having a convex surface facing the object side. The zoom lens according to any one of claims 1 to 3,
The following conditional expression is satisfied.
6.0 <f1 / (− f2) <10.0
However,
f2: Focal length of the second lens group In the zoom lens according to any one of claims 1 to 4,
The zoom lens according to claim 5, wherein when the focal length changes from the wide-angle end state to the telephoto end state, the fifth lens group moves relative to the image plane along the optical axis in the infinite focus state. The zoom lens according to any one of claims 1 to 5,
A zoom lens comprising at least one aspheric lens in the fourth lens group. The zoom lens according to any one of claims 1 to 6,
The third lens group includes, in order from the object side, a first partial lens group having a positive refractive power, an aperture stop, and a second partial lens group having a positive refractive power. . The zoom lens according to any one of claims 1 to 7,
The third lens group includes, in order from the object side, a cemented lens having a positive refractive power composed of a meniscus negative lens having a convex surface facing the object side and a positive lens having a convex surface facing the object side, and an aperture stop And a cemented lens having a positive refractive power composed of a positive lens having a convex surface on the object side and a meniscus negative lens having a convex surface on the image side. The zoom lens according to any one of claims 1 to 8,
A zoom lens satisfying the following conditions:
1.6 <f3a / f3 <2.5
However,
f3a: focal length of the first partial lens group The zoom lens according to any one of claims 1 to 9,
A zoom lens, wherein the fifth lens group is moved toward the object side to perform focus adjustment from a long-distance object to a short-distance object. The zoom lens according to any one of claims 1 to 10,
A zoom lens satisfying the following conditions:
3.8 <f5 / fw <6.0
However,
f5: focal length of the fifth lens group The zoom lens according to any one of claims 1 to 11,
A zoom lens comprising at least one aspherical lens in the second lens group.

Images