JP4642408B2 - Zoom lens and camera using the same - Google Patents

Description

  The present invention relates to a wide-angle zoom lens and a camera using the same, and more particularly to a high-performance wide-angle zoom lens suitable for an electronic image sensor used in a single-lens reflex camera or the like and a camera using the same. It is.

2. Description of the Related Art Conventionally, zoom lenses of a type preceded by a negative lens group as described in the following Patent Documents 1 to 3, for example, are known as zoom lenses that are generally easy to widen the angle of view.
JP-A-60-130712 JP-A-62-200316 Japanese Patent Laid-Open No. 10-82594

The zoom lens described in Patent Document 1 includes a first lens group having a negative refractive power and a second lens group having a positive refractive power in order from the object side, and is a zoom lens having a minimum F number of about 3.6. It is configured.
The zoom lens described in Patent Document 2 includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and has a wide angle end half field angle of about 37 °. It is configured as a zoom lens.
The zoom lens described in Patent Document 3 is configured as a four-group zoom lens having a minimum F number of about 3.6.

In such a type of zoom lens preceded by a negative lens group, in order to achieve a large aperture and high performance, and to make the incident angle of the light beam on the imaging surface close to vertical, the configuration of the rear group is appropriate. There is a need.
However, as in these zoom lenses, when the half angle of view at the wide-angle end is about 37 ° and the F-number is about 3.6, it is disadvantageous to achieve both a wide angle of view and a large aperture. It is.

  The present invention has been made in view of the above-described conventional problems, and the second lens group of such a negative-preceding type zoom lens is optimized to achieve a wide field angle and a bright F-number. Advanced zoom lens and camera using the same, specifically, a high-performance zoom lens with a maximum half angle of view of 45 ° or more at the wide-angle end and a minimum F number of about 2.8, and the use thereof The purpose is to provide a camera.

To achieve the above object, the zoom lens of the present invention, in order from the object side, a first lens group having negative refractive power, a second lens group having a positive refractive power, at least two groups Interval A zoom lens that performs zooming by changing a zoom lens, wherein an aperture stop is disposed between the first lens group and the second lens group, and the second lens group is sequentially positive from the object side. A biconvex first lens having a refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a biconvex fourth lens having a positive refractive power; And a fifth lens having a negative refractive power and a biconvex sixth lens having a positive refractive power and satisfying the following conditional expression .
0.07 <d12 / f2G <0.3 0
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.07 <d12 / f2G <0.17
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the second lens and the third lens are cemented, and the fifth lens and the sixth lens are cemented.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction A biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, the second lens and the third lens, Are joined, and the fifth lens and the sixth lens are joined. It is characterized by satisfying the expressions.
0.07 <d12 / f2G < 0.17
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.5 <f1 / f2G <1.0
Here, f1 is the focal length of the first lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−1.0 <f23 / f2G <−0.4
Here, f23 is a combined focal length of the second lens and the third lens, and f2G is a focal length of the second lens group.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction Including a biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, satisfying the following conditional expression: It is said.
0.07 <d12 / f2G <0.30
−1.0 <f23 / f2G <−0.4
However, d12 is the air space on the optical axis sandwiched between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−0.5 <f2G / f56 <0
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens.

In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction Including a biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, satisfying the following conditional expression: It is said.
0.15 <d12 / f2G <0.25
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the second lens has a positive refractive power and the third lens has a negative refractive power.
In the zoom lens according to the present invention, it is preferable that the second lens and the third lens are cemented, and the fifth lens and the sixth lens are cemented.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a biconvex fourth lens having a positive refractive power. A fifth lens having a negative refracting power, and a biconvex sixth lens having a positive refracting power, wherein the second lens and the third lens are joined, and the fifth lens The sixth lens is cemented and satisfies the following conditional expression:
0.07 <d12 / f2G <0.30
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.8 <f1 / f2G <1.5
Here, f1 is the focal length of the first lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−1.5 <f23 / f2G <−0.8
Here, f23 is a combined focal length of the second lens and the third lens, and f2G is a focal length of the second lens group.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction Including a biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, satisfying the following conditional expression: It is said.
0.07 <d12 / f2G <0.30
−1.5 <f23 / f2G <−0.8
However, d12 is the air space on the optical axis sandwiched between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−0.1 <f2G / f56 <0.05
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens.

Further, in the zoom lens of the present invention, preferably, prior Symbol fourth lens is characterized by a single lens having at least one aspherical surface.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.5 <f1 / f2G <2. 0
Here, f1 is the focal length of the first lens, and f2G is the focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−2.0 <f23 / f2G <−0.4
However, f23 is the composite focal length of the third lens and the second lens, f2G is the focal length of the second lens group.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction Including a biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, satisfying the following conditional expression: It is said.
0.07 <d12 / f2G <0.30
−2.0 <f23 / f2G <−0.4
However, d12 is the air space on the optical axis sandwiched between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.4 <f4 / f2G <1.5
Here, f4 is the focal length of the fourth lens, and f2G is the focal length of the second lens group.
In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.5 <f4 / f2G <1.0
Here, f4 is the focal length of the fourth lens, and f2G is the focal length of the second lens group .
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the second lens group is arranged in order from the object side. A biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and positive refraction Including a biconvex fourth lens having power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power, satisfying the following conditional expression: It is said.
0.07 <d12 / f2G <0.30
0.5 <f4 / f2G <1.0
However, d12 is the air space on the optical axis between the first lens and the second lens, f2G is the focal length of the second lens group, and f4 is the focal length of the fourth lens.
In the zoom lens of the present invention, it is preferable that the first lens group includes, in order from the object side, a plurality of negative lenses having a concave surface on the image plane side, a positive lens, a negative lens, and a positive lens. It is characterized by becoming.
In order to achieve the above object, the zoom lens of the present invention includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and at least both groups. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, and the first lens group is arranged in order from the object side. A plurality of negative lenses having a concave surface on the image surface side, a positive lens, a negative lens, and a positive lens, and the second lens group has a biconvex shape having a positive refractive power in order from the object side. A first lens, a second lens having a positive or negative refractive power, a third lens having a refractive power different from that of the second lens, and a biconvex fourth lens having a positive refractive power; A fifth lens with negative refractive power and a biconvex shape with positive refractive power And a sixth lens, and satisfies the following condition.
0.07 <d12 / f2G <0.30
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group.
In the zoom lens of the present invention, it is preferable that two negative lenses on the object side in the plurality of negative lenses are constituted by negative meniscus lenses.
In the zoom lens according to the present invention, preferably, the positive lens arranged subsequent to the plurality of negative lenses is formed in a biconvex shape.
In the zoom lens according to the present invention, it is preferable that the second lens has a positive refractive power and the third lens has a negative refractive power.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
−0.5 <f2G / f56 <0. 1
However, f2G is the focal length of the second lens group, f56 is a composite focal length of the before and Symbol fifth lens the sixth lens.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.8 <GD26 / SD26 < 1
However, GD26 before Symbol second lens, the third lens, the fourth lens, the object of the fifth lens, and the sum of the thickness on the optical axis of the sixth lens, SD26 before Symbol second lens This is the length on the optical axis from the side surface to the image side surface of the sixth lens.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.9 <GD26 / SD26 < 1
However, GD26 is the total thickness on the optical axis of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, and SD26 is from the object side surface of the second lens. It is the length on the optical axis to the image side surface of the sixth lens.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.4 <SD26 / f2G < 1
Where SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens, and f2G is the focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
0.5 <SD26 / f2G <0. 9
Where SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens, and f2G is the focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
1 <| f1G | / DS < 3
Where f1G is the focal length of the first lens group, and DS is the first lens group and the second lens when the focal length of the entire zoom lens system is -0.8 times the focal length of the first lens group. This is the lens surface distance between the lens groups.

In the zoom lens according to the present invention, it is preferable that the following conditional expression is satisfied.
1.2 <| f1G | / DS < 2
Where f1G is the focal length of the first lens group, and DS is the first lens group and the second lens when the focal length of the entire zoom lens system is -0.8 times the focal length of the first lens group. This is the lens surface distance between the lens groups.

  The zoom lens according to the present invention is preferably characterized in that an image is formed in a region where the total angle of view at the wide angle end is 90 ° or more.

  In the zoom lens according to the present invention, it is preferable that the zoom lens is configured as a two-group zoom lens having only two lens groups that move during zooming.

  The camera according to the present invention is characterized by using the zoom lens according to the present invention.

  As is apparent from the above description, according to the present invention, it is possible to provide a negative leading type zoom lens capable of achieving a wide angle of view and a bright F number.

Prior to the description of the embodiments, the effects of the present invention will be described.
When the zoom lens according to the present invention has a first lens group having a negative refractive power and a second lens group having a positive refractive power, the second lens group has a negative refractive power. It has the effect of converging the light rays diverging from the first lens group with a strong positive refractive power. In particular, in order to obtain a zoom lens having a half angle of view at the wide angle end of about 45 °, it is necessary to increase the diverging action of the first lens group. On the other hand, when the zoom lens is a two-group zoom, the second lens group also has an action of determining the exit pupil position.

  In order to obtain good imaging performance, a configuration that causes these effects is desirable. That is, according to the present invention, the axial light beam diverging through the first lens group is converted into a convergent light beam by the first lens of the second lens group located in the vicinity of the aperture stop, and the subsequent lens groups. Do not increase the outer diameter. In this way, it is possible to suppress the occurrence of higher-order aberrations in the rear group, and to reduce image deterioration due to decentration as a whole. On the other hand, the principal point position of the entire second lens group can be arranged on the object side, which is advantageous in increasing the zoom ratio.

If the second lens to the sixth lens are arranged at an appropriate interval satisfying the conditional expression (1), the exit pupil can be placed far away, and the incident angle of the off-axis light beam on the imaging surface is made closer to the vertical. be able to.
0.07 <d12 / f2G <0.30 (1)
Here, d12 is an air interval on the optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.

If the lower limit of conditional expression (1) is not reached, the position of the exit pupil will be close, the incident angle of the light beam on the image plane will be too tilted, and there will be problems such as insufficient peripheral light intensity and shading when an image sensor is placed The possibility that this will occur will increase.
On the other hand, if the upper limit value of conditional expression (1) is exceeded, the total length of the second lens group becomes longer, and the balance between the incident position of the on-axis light beam and the off-axis light beam on the second lens deteriorates, resulting in good performance. It becomes difficult to put out.
The configuration of the present invention is desirable because the second lens group can be considered as a front group consisting of the first lens and a rear group consisting of the second lens and the subsequent five lenses. .
In the zoom lens of the present invention, if the refractive power of the five or six lenses in the second lens group is symmetrical, and the positive and negative lenses are substantially alternately arranged, the entire aberration is obtained. This is easy to balance and is advantageous for aberration correction.

  For example, in the zoom lens of the present invention, if the arrangement of the refractive powers of the second lens to the sixth lens is arranged symmetrically with positive, negative, positive and negative, the performance of off-axis light beam can be particularly secured. Further, the chromatic aberration can be efficiently corrected by arranging the positive lens and the negative lens alternately.

  Further, in the zoom lens according to the present invention, if the refractive powers of the first lens to the third lens and the fourth lens to the sixth lens are arranged symmetrically with respect to positive and negative, respectively, the off-axis light beam is particularly good. Performance can be ensured. Also in this case, chromatic aberration can be corrected efficiently by alternately arranging positive lenses and negative lenses.

Note that the lower limit of conditional expression (1) in the zoom lens of the present invention is preferably 0.15. Further, the upper limit value of conditional expression (1) is preferably 0.25, and more preferably 0.17.
In particular, when the arrangement of the second lens and the third lens is a positive lens and a negative lens, it is preferable that the following conditional expression (1 ′) is satisfied because various performances can be easily balanced.
0.15 <d12 / f2G <0.25 (1 ')
Here, d12 is an air interval on the optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.
Further, when the arrangement of the second lens and the third lens is a negative lens and a positive lens, it is preferable to satisfy the following conditional expression (1 ") because various performances can be easily balanced.
0.07 <d12 / f2G <0.17 (1 ")
Here, d12 is an air interval on the optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.

By the way, if each lens element in the second lens group is decentered, asymmetric coma and astigmatism are generated, and the imaging performance is deteriorated.
However, in the zoom lens according to the present invention, if the second lens and the third lens, and the fifth lens and the sixth lens are each composed of a cemented lens, image deterioration due to decentering caused by an incorporation error of each lens element. Easy to reduce.

  In the zoom lens of the present invention, if the fourth lens is a positive single lens, it becomes easier to ensure the symmetry of refractive power in the second lens group. Furthermore, if at least one surface of the fourth lens is aspherical, image deterioration due to decentering can be reduced. In particular, the above effect is further increased if both aspheric surfaces are used. In other words, the aspherical surface enables a sufficient aberration correction even if the refractive power of the lens surface is weakened, and the fluctuation of the optical axis due to decentration can be reduced.

In the zoom lens of the present invention, it is preferable that the focal length of the first lens in the second lens group satisfies the following conditional expression (2).
0.5 <f1 / f2G <2.0 (2)
Here, f1 is the focal length of the first lens in the second lens group, and f2G is the focal length of the second lens group.
If the lower limit of conditional expression (2) is not reached, the refractive power of the first lens becomes too strong, and it becomes difficult to obtain good imaging performance while satisfying conditional expression (1).
On the other hand, if the upper limit value of conditional expression (2) is exceeded, the refractive power of the first lens becomes too weak, and the outer diameter after the second lens tends to increase. In addition, it is difficult to maintain a balance between the incident diameter of the on-axis light beam and the incident position of the off-axis light beam on the second lens.

In the zoom lens according to the present invention, the lower limit value of the conditional expression (2) is preferably 0.8. The upper limit value of conditional expression (2) is preferably 1.5, and more preferably 1.0.
In particular, when the arrangement of the second lens and the third lens is a positive lens and a negative lens,
If the following conditional expression (2 ′) is satisfied, it is preferable because various performances can be more easily balanced.
0.8 <f1 / f2G <1.5 (2 ')
Here, f1 is the focal length of the first lens in the second lens group, and f2G is the focal length of the second lens group.
In addition, when the arrangement of the second lens and the third lens is a negative lens and a positive lens,
If the following conditional expression (2 ") is satisfied, it is preferable because various performances can be more easily balanced.
0.5 <f1 / f2G <1.0 (2 ")
Here, f1 is the focal length of the first lens in the second lens group, and f2G is the focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that a combined focal length of the second lens and the third lens in the second lens group satisfies the following conditional expression (3).
−2.0 <f23 / f2G <−0.4 (3)
Here, f23 is a combined focal length of the second lens and the third lens in the second lens group, and f2G is a focal length of the second lens group.
If the lower limit of conditional expression (3) is not reached, the combined refractive power of the second lens and the third lens becomes too weak, and the position of the principal point of the sixth lens from the second lens can be arranged sufficiently on the image side. Therefore, it is difficult to properly secure the exit pupil position.
On the other hand, if the upper limit value of conditional expression (3) is exceeded, the combined refractive power of the second lens and the third lens becomes too strong, and it is required to increase the positive refractive power in other lenses. It becomes difficult to ensure the accuracy of the surface.

In the zoom lens of the present invention, the lower limit value of conditional expression (3) is preferably −1.5, and more preferably −1. Further, it is preferable to set the upper limit value of conditional expression (3) to −0.8.
In particular, when the arrangement of the second lens and the third lens is a positive lens and a negative lens, it is preferable that the following conditional expression (3 ′) is satisfied because various performances can be easily balanced.
−1.5 <f23 / f2G <−0.8 (3 ′)
Here, f23 is a combined focal length of the second lens and the third lens in the second lens group, and f2G is a focal length of the second lens group.
Further, when the arrangement of the second lens and the third lens is a negative lens and a positive lens, it is preferable that the following conditional expression (3 ") is satisfied because various performances can be easily balanced.
−1.0 <f23 / f2G <−0.4 (3 ")
Here, f23 is a combined focal length of the second lens and the third lens in the second lens group, and f2G is a focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that the focal length of the fourth lens in the second lens group satisfies the following conditional expression (4).
0.4 <f4 / f2G <1.5 (4)
Here, f4 is a focal length of the fourth lens in the second lens group, and f2G is a focal length of the second lens group.
If the lower limit of conditional expression (4) is not reached, the refractive power of the fourth lens becomes too strong, making it difficult to suppress image deterioration due to decentration.
On the other hand, if the upper limit value of conditional expression (4) is exceeded, the refractive power of the fourth lens becomes too weak, making it difficult to ensure the exit pupil position properly.

In the zoom lens of the present invention, the lower limit value of conditional expression (4) is preferably 0.5. Further, the upper limit value of conditional expression (4) is preferably 1.0.
In particular, it is preferable that the following conditional expression (4 ′) is satisfied because various performances can be more easily balanced.
0.5 <f4 / f2G <1.0 (4 ′)
Here, f4 is a focal length of the fourth lens in the second lens group, and f2G is a focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that a combined focal length of the fifth lens and the sixth lens in the second lens group satisfies the following conditional expression (5).
-0.5 <f2G / f56 <0.1 (5)
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens in the second lens group.
If the lower limit of conditional expression (5) is not reached, the combined refractive power of the fifth lens and the sixth lens becomes too negative, and the position of the principal point of the sixth lens from the second lens can be located sufficiently on the image side. Therefore, it is difficult to properly secure the exit pupil position.
On the other hand, if the upper limit value of conditional expression (5) is exceeded, the combined refractive power of the fifth lens and the sixth lens becomes too strong, and the outer diameters of these lenses become too large. In addition, the aberration correction effect with the negative fifth lens is reduced.

In the zoom lens of the present invention, it is preferable that the lower limit value of the conditional expression (5) is −0.1. Further, the upper limit value of conditional expression (5) is preferably 0.05, and more preferably 0.
In particular, when the arrangement of the second lens and the third lens is a positive lens and a negative lens, it is preferable that the following conditional expression (5 ′) is satisfied because various performances can be easily balanced.
−0.1 <f2G / f56 <0.05 (5 ′)
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens in the second lens group.
In addition, when the second lens and the third lens are arranged in a negative lens and a positive lens, it is preferable to satisfy the following conditional expression (5 ") because various performances can be easily balanced.
-0.5 <f2G / f56 <0 (5 ")
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens in the second lens group.

In the zoom lens according to the present invention, it is preferable that the second to sixth lenses in the second lens group satisfy the following conditional expression (6).
0.8 <GD26 / SD26 <1 (6)
However, GD26 is the total thickness on the optical axis of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens in the second lens group, and SD26 is the This is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens in the second lens group.
If the lower limit value of conditional expression (6) is not reached, the total thickness of the sixth lens from the second lens of the second lens group decreases, and it becomes difficult to correct astigmatism.
On the other hand, if the upper limit of conditional expression (6) is exceeded and becomes 1, all the lenses from the second lens to the sixth lens are joined on the optical axis, and it becomes difficult to secure a space necessary for holding the lens. .

In the zoom lens of the present invention, it is more advantageous for astigmatism when the lower limit value of conditional expression (6) is 0.9. That is, it is preferable that the following conditional expression (6 ′) is satisfied.
0.9 <GD26 / SD26 <1 (6 ')
However, GD26 is the total thickness on the optical axis of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens in the second lens group, and SD26 is the This is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens in the second lens group.

In the zoom lens according to the present invention, it is preferable that the second to sixth lenses in the second lens group satisfy the following conditional expression (7).
0.4 <SD26 / f2G <1 (7)
SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens in the second lens group, and f2G is the focal length of the second lens group.
If the lower limit value of conditional expression (7) is not reached, the distance from the object side surface of the second lens to the sixth lens image side surface becomes short, and aberration correction becomes difficult.
On the other hand, if the upper limit value of conditional expression (7) is exceeded, it will become difficult to satisfy conditional expression (1) or it will be difficult to ensure the required back focus.

In the zoom lens of the present invention, it is preferable that the lower limit value of conditional expression (7) is 0.5. Moreover, it is preferable to set the upper limit of conditional expression (7) to 0.9.
In particular, it is preferable that the following conditional expression (7 ′) is satisfied because various performances can be more easily balanced.
0.5 <SD26 / f2G <0.9 (7 ')
SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens in the second lens group, and f2G is the focal length of the second lens group.

In the zoom lens according to the present invention, it is preferable that a surface interval between the first lens group and the second lens group satisfies the following conditional expression (8).
1 <| f1G | / DS <3 (8)
Where f1G is the focal length of the first lens group, and DS is the first lens group and the second lens when the focal length of the entire zoom lens system is -0.8 times the focal length of the first lens group. This is the lens surface distance between the lens groups.
If the upper limit of conditional expression (8) is exceeded, the magnification after the second lens group with respect to the first lens group at the telephoto end becomes too large, the burden of aberration correction in the first lens group becomes large, and the number of lenses increases. It becomes easy to increase.
On the other hand, if the lower limit of conditional expression (8) is not reached, the entire zoom lens system becomes longer, and in particular, the outer diameter of the first lens group tends to increase.

  More preferably, in the zoom lens according to the present invention, a configuration in which the magnification after the second lens unit at the telephoto end is in the vicinity of -1, more specifically, -0.9 times to -1.2 times is preferable. By doing so, satisfying conditional expression (8) makes it easy to secure an appropriate focal length of the first lens group while securing a configuration necessary for aberration correction.

In the zoom lens of the present invention, the lower limit value of conditional expression (8) is preferably 1.2. Also, it is preferable to set the upper limit value of conditional expression (8) to 2.
In particular,
1.2 <| f1G | / DS <2
It is more preferable.

In the zoom lens according to the present invention, the first lens group may include a plurality of negative lenses having a concave surface on the image plane side, a positive lens, a negative lens, and a positive lens in order from the object side. preferable.
With this configuration, by disposing a plurality of negative lenses having concave surfaces from the object side to the image surface side, it is possible to correct distortion that increases rapidly at the wide-angle end, which is advantageous for widening the angle of view. Become. Then, a combination of a positive lens, a negative lens, and a positive lens, which are arranged subsequent to them, provides a zoom lens that can easily perform correction with balanced on-axis aberration and off-axis aberration.

Furthermore, in the zoom lens according to the present invention, it is easy to suppress the occurrence of off-axis high-order aberrations such as coma aberration by using two object side lenses as negative meniscus lenses. Further, if a negative lens is arranged on the third lens following the third lens, it becomes easy to correct off-axis high-order aberrations such as coma generated in the second negative lens.
More preferably, in the zoom lens according to the present invention, if the positive lens arranged following the plurality of negative lenses is formed in a biconvex shape, the axial aberration generated by the plurality of negative lenses on the object side is corrected. It becomes easy.
More preferably, if a negative lens arranged next to the positive lens has a convex surface on the image side, the correction level of high-order aberrations can be increased, and bright and good imaging performance can be obtained more easily. This is preferable.

In the zoom lens according to the present invention, it is preferable that an image is formed in a region where the full field angle (2ω) at the wide-angle end is 90 ° or more.
The zoom lens of the present invention has a group configuration that facilitates widening of the angle of view. Therefore, it is preferable that the zoom lens has a wide angle of view with a wide angle end angle of view of 90 ° or more.
In the zoom lens according to the present invention, the image may be formed in a region where the total angle of view is 93 ° or more.

  In the zoom lens according to the present invention, it is preferable that the zoom lens is constituted by a two-group zoom lens in which only two lens groups move during zooming. If comprised in this way, the moving mechanism accompanying zooming can be simplified.

In addition, the zoom lens according to the present invention may be configured by combining a plurality of the above-described configurations. Further, the plurality of conditional expressions may be arbitrarily combined to be satisfied.
Further, the upper limit value or lower limit value in each conditional expression may be individually limited, and the conditional expression corresponding values in the embodiments described below may be used as the upper limit value or the lower limit value.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a sectional view along the optical axis showing the optical configuration of the zoom lens according to the first embodiment of the present invention, where (a) is at the wide angle end, (b) is in the middle, and (c) is at the telephoto end. Show. FIG. 2 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to the first example, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown. FIG. 3 is a diagram showing spherical aberration, astigmatism, and distortion when the zoom lens according to the first embodiment is focused at a shooting distance of 0.4 m, where (a) is the wide-angle end, (b) is the middle, c) shows the state at the telephoto end.

  The zoom lens according to the first embodiment includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface directed to the image side, a negative meniscus lens L12 having a concave surface directed to the image side, a biconcave lens L13, a biconvex lens L14, and an object side And a negative meniscus lens L15 having a concave surface directed toward the object side, and a positive meniscus lens L16 having a convex surface directed toward the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a concave surface directed toward the object side, and a biconcave lens L23, a biconvex lens L24, a biconcave lens L25, and a biconvex lens L26. And has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, in focusing in any zoom state from the wide-angle end to the telephoto end, focusing from infinity to the closest distance moves the front group G1a of the first lens group G1 to the image side and moves the rear group G1b to the object side. To do.
For focusing, other moving methods such as moving the entire first lens group G1 integrally or moving only the rear group G1b may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface directed to the image side, and on both surfaces of the biconvex lens L24.
Next, numerical data of optical members constituting the zoom lens of the first embodiment are shown.
In the numerical data of the first embodiment, r ₁ , r ₂ ,... Are the curvature radii of the lens surfaces, d ₁ , d ₂ ,... Are the thickness or air spacing of the lenses, n _d1 , n _d2,. Is the refractive index of each lens at the d-line, ν _d1 , ν _d2 ,... Is the Abbe number of each lens, Fno. Is the F number, f is the focal length of the entire system, and 2ω is the total angle of view.
The aspherical shape is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis is y, the conical coefficient is K, and the aspherical coefficients are A ₄ , A ₆ , A ₈ , A _10. It is represented by
z = (y ² / r) / [1+ {1− (1 + K) (y / r) ² } ^1/2 ]
+ A ₄ y ⁴ + A ₆ y ⁶ + A ₈ y ⁸ + A ₁₀ y ¹⁰
These symbols are common to the following embodiments.

Numerical data 1
Wide angle end Medium telephoto end f 11.21 16.10 21.57
Fno. 2.85 3.16 3.53
2ω 93.8 ° 72.2 ° 56.9 °

r ₁ = 39.5894 d ₁ = 2.7500 n _d1 = 1.77250 ν _d1 = 49.60
r ₂ = 19.2336 d ₂ = 4.1319
_{r 3 = 23.4925 d 3 = 2.900} n d3 = 1.80610 ν d3 = 40.92
r ₄ = 12.5636 (aspherical surface) d ₄ = 9.3097
r ₅ = −298.3827 d ₅ = 1.8000 n _d5 = 1.80440 ν _d5 = 39.59
r ₆ = 43.4758 d ₆ = 5.3592
r ₇ = 57.7472 d ₇ = 4.3200 n _d7 = 1.75520 ν _d7 = 27.51
r ₈ = -57.7472 d ₈ = D8
_{r 9 = -43.5463 d 9 = 1.7000} n d9 = 1.88300 ν d9 = 40.76
r ₁₀ = −625.1817 d ₁₀ = 0.1000
r ₁₁ = 70.6025 d ₁₁ = 2.8000 n _d11 = 1.78472 ν _d11 = 25.68
r ₁₂ = 250.1754 d ₁₂ = D12
r ₁₃ = (aperture) d ₁₃ = 1.000
r ₁₄ = 28.5691 d ₁₄ = 3.4441 n _d14 = 1.57099 ν _d14 = 50.80
r ₁₅ = −62.3093 d ₁₅ = 6.7403
r ₁₆ = −108.7751 d ₁₆ = 3.1918 n _d16 = 1.48749 ν _d16 = 70.23
r ₁₇ = -16.8629 d ₁₇ = 1.6600 n _d17 = 1.83481 ν _d17 = 42.72
r ₁₈ = 419.5895 d ₁₈ = 0.4519
r ₁₉ = 31.3057 (aspherical surface) d ₁₉ = 9.2900 n _d19 = 1.58313 ν _d19 = 59.38
r ₂₀ = -25.4261 (aspherical surface) d ₂₀ = 0.2606
r ₂₁ = 43.7765 d ₂₁ = 1.3700 n _d21 = 1.80440 ν _d21 = 39.59
r ₂₂ = 24.0803 d ₂₂ = 7.2430 n _d22 = 1.48749 ν _d22 = 70.23
r ₂₃ = -18.7623 d ₂₃ = D23
r ₂₄ = ∞ d ₂₄ = 4.6500 n _d24 = 1.51633 ν _d24 = 64.14
r ₂₅ = ∞ d ₂₅ = 1.000
r ₂₆ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -1.1929
A ₄ = 3.5604 × 10 ^-5 A ₆ = -8.7009 × 10 ^-10 A ₈ = 2.2597 × 10 ^-10
A ₁₀ = -8.9735 × 10 ^-13
19th side K = -2.5703
A ₄ = -1.6964 × 10 ^-7 A ₆ = 2.9944 × 10 ^-8 A ₈ = 3.6253 × 10 ^-10
A ₁₀ = -3.2098 × 10 ^-12
20th page K = -1.1772
A ₄ = 2.7778 × 10 ^-5 A ₆ = 1.6530 × 10 ^-8 A ₈ = -1.3383 × 10 ^-10
A ₁₀ = 0.0000 × 10 ⁰

Zoom data (when focusing on an object point at infinity)
Surface interval Wide-angle end Medium telephoto end D8 4.80120 4.80120 4.80120
D12 29.52601 11.92308 1.70262
D23 30.74933 39.35719 48.97985
(When the object distance is 0.4m)
Inter-surface distance Wide-angle end Medium telephoto end D8 2.63974 2.70750 2.71188
D12 31.49134 13.82644 3.60201

  FIG. 4 is a sectional view along the optical axis showing the optical configuration of the zoom lens according to the second embodiment of the present invention, where (a) is at the wide-angle end, (b) is in the middle, and (c) is at the telephoto end. Show. FIG. 5 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to the second example, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown. FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion when the zoom lens according to the second embodiment has a focal length of 0.4 m, (a) is the wide angle end, (b) is the middle, c) shows the state at the telephoto end.

  The zoom lens according to the second embodiment includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface directed to the image side, a negative meniscus lens L12 having a concave surface directed to the image side, a biconcave lens L13, a biconvex lens L14, and an object side And a negative meniscus lens L15 having a concave surface directed toward the object side, and a positive meniscus lens L16 having a convex surface directed toward the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a concave surface directed toward the object side, and a biconcave lens L23, a biconvex lens L24, a biconcave lens L25, and a biconvex lens L26. And has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end moves the front group G1a of the first lens group G1 to the image side and moves the rear group G1b to the object side. To do.
For focusing, other moving methods such as moving the entire first lens group G1 integrally or moving only the rear group G1b may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface directed to the image side, and on both surfaces of the biconvex lens L24.
Next, numerical data of optical members constituting the zoom lens of the second embodiment are shown.

Numerical data 2
Wide-angle end Middle Telephoto end f 11.25 16.09 21.59
Fno. 2.8500 3.1512 3.5064
2ω 93.4 ° 72.4 ° 56.9 °

r ₁ = 39.4656 d ₁ = 2.7000 n _d1 = 1.77250 ν _d1 = 49.60
r ₂ = 19.1575 d ₂ = 3.8376
r ₃ = 23.4988 d ₃ = 2.9000 n _d3 = 1.80610 ν _d3 = 40.92
r ₄ = 12.3518 (aspherical surface) d ₄ = 8.7545
r ₅ = −321.5338 d ₅ = 1.7500 n _d5 = 1.80440 ν _d5 = 39.59
r ₆ = 38.1909 d ₆ = 5.6587
r ₇ = 51.8517 d ₇ = 4.2500 n _d7 = 1.774077 ν _d7 = 27.79
r ₈ = -62.4189 d ₈ = D8
_{r 9 = -49.8100 d 9 = 1.7000} n d9 = 1.88300 ν d9 = 40.76
r ₁₀ = -634.3371 d ₁₀ = 0.1000
r ₁₁ = 76.0148 d ₁₁ = 2.8000 n _d11 = 1.78472 ν _d11 = 25.68
r ₁₂ = 279.3232 d ₁₂ = D12
r ₁₃ = (aperture) d ₁₃ = 1.000
r ₁₄ = 26.6837 d ₁₄ = 3.5381 n _d14 = 1.53172 ν _d14 = 48.84
r ₁₅ = -58.7525 d ₁₅ = 6.6753
r ₁₆ = −105.7861 d ₁₆ = 3.2705 n _d16 = 1.48749 ν _d16 = 70.23
r ₁₇ = -16.5092 d ₁₇ = 1.6600 n _d17 = 1.83481 ν _d17 = 42.72
r ₁₈ = 483.0727 d ₁₈ = 0.5116
r ₁₉ = 31.5949 (aspherical surface) d ₁₉ = 9.6340 n _d19 = 1.58913 ν _d19 = 61.14
r ₂₀ = -24.9249 (aspherical surface) d ₂₀ = 0.3176
r ₂₁ = -43.5703 d ₂₁ = 1.3700 n _d21 = 1.80440 ν _d21 = 39.59
r ₂₂ = 23.2096 d ₂₂ = 7.6628 n _d22 = 1.48749 ν _d22 = 70.23
r ₂₃ = -18.8170 d ₂₃ = D23
r ₂₄ = ∞ d ₂₄ = 4.6500 n _d24 = 1.51633 ν _d24 = 64.14
r ₂₅ = ∞ d ₂₅ = 1.000
r ₂₆ = ∞ (image plane) d ₂₆ = 0

Aspheric data 2nd surface K = -1.2568
A ₄ = 4.0845 × 10 ^-5 A ₆ = 7.9534 × 10 ^-9 A ₈ = 1.4928 × 10 ^-10
A ₁₀ = -6.6801 × 10 ^-13
19th side K = -2.9863
A ₄ = 6.2363 × 10 ^-9 A ₆ = 3.8233 × 10 ^-8 A ₈ = 2.5629 × 10 ^-10
A ₁₀ = -3.2996 × 10 ^-12
20th page K = -1.2082
A ₄ = 2.6128 × 10 ^-5 A ₆ = 2.9162 × 10 ^-8 A ₈ = -2.7710 × 10 ^-10
A ₁₀ = 0.0000 × 10 ⁰

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D8 3.67042 3.67042 3.67042
D12 30.02014 12.13323 1.54340
D23 30.83039 39.33862 49.00113
(When the object distance is 0.4m)
Surface interval Wide-angle end Medium telephoto end D8 1.05911 1.14556 1.15380
D12 32.41585 14.44961 3.85223

  FIG. 7 is a cross-sectional view along the optical axis showing the optical configuration of the zoom lens according to the third embodiment of the present invention, where (a) is at the wide-angle end, (b) is in the middle, and (c) is at the telephoto end. Show. FIG. 8 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 3, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown.

  The zoom lens according to the third example includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, and a negative meniscus lens L13 ′ having a concave surface facing the image side. And a biconvex lens L14, a biconcave lens L15 ′, and a positive meniscus lens L16 having a convex surface facing the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a concave surface directed toward the object side, and a biconcave lens L23, a biconvex lens L24, a biconcave lens L25, and a biconvex lens L26. And has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end is performed by fixing the second lens group G2 and moving the entire first lens group G1 integrally to the image side. It has become.
As for focusing, other moving methods such as moving a plurality of lens groups constituting the first lens group G1 or extending the entire zoom lens may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface directed to the image side, and on both surfaces of the biconvex lens L24.
Next, numerical data of optical members constituting the zoom lens of the third example are shown.

Numerical data 3
Wide-angle end Middle Telephoto end f 11.08 16.08 21.17
Fno. 2.8500 3.16 3.49
2ω 90.3 ° 69.4 ° 55.5 °

r ₁ = 40.0655 d ₁ = 2.7 n _d1 = 1.7725 ν _d1 = 49.6
r ₂ = 17.5863 d ₂ = 6.612
r ₃ = 25.7506 d ₃ = 2.9 n _d3 = 1.8061 ν _d3 = 40.92
r ₄ = 12.0877 (aspherical surface) d ₄ = 10.3638
r ₅ = 76.6337 d ₅ = 1.6 n _d5 = 1.8044 ν _d5 = 39.59
r ₆ = 35.3282 d ₆ = 2.1363
r ₇ = 33.4764 d ₇ = 4.7115 n _d7 = 1.72825 ν _d7 = 28.46
r ₈ = -185.2077 d ₈ = D8
r ₉ = -89.4707 d ₉ = 1.5 n _d9 = 1.883 ν _d9 = 40.76
r ₁₀ = 75.9172 d ₁₀ = 0.291
r ₁₁ = 52.6242 d ₁₁ = 3 n _d11 = 1.76182 ν _d11 = 26.52
r ₁₂ = 441.0221 d ₁₂ = D12
r ₁₃ = (aperture) d ₁₃ = 1
r ₁₄ = 32.9566 d ₁₄ = 3.4867 n _d14 = 1.56732 ν _d14 = 42.82
r ₁₅ = −63.1956 d ₁₅ = 5.5488
r ₁₆ = 509.8453 d ₁₆ = 3.99566 n _d16 = 1.497 ν _d16 = 81.54
r ₁₇ = -18.2618 d ₁₇ = 1.7488 n _d17 = 1.804 ν _d17 = 46.57
r ₁₈ = 56.1153 d ₁₈ = 0.1174
r ₁₉ = 23.7029 (aspherical surface) d ₁₉ = 8.1876 n _d19 = 1.58313 ν _d19 = 59.38
r ₂₀ = -25.8538 (aspherical surface) d ₂₀ = 0.1076
r ₂₁ = -53.7863 d ₂₁ = 2.9145 n _d21 = 1.8061 ν _d21 = 40.92
r ₂₂ = 20.0996 d ₂₂ = 8.9527 n _d22 = 1.497 ν _d22 = 81.54
r ₂₃ = -19.0753 d ₂₃ = D23 n _d23 = 31.30349
r ₂₄ = ∞ d ₂₄ = 4.65 n _d24 = 1.51633 ν _d24 = 64.14
r ₂₅ = ∞ d ₂₅ = 1
r ₂₆ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -0.9686
A ₄ = 1.3528 × 10 ^-5 A ₆ = -2.1707 × 10 ^-8 A ₈ = 1.0537 × 10 ^-10
A ₁₀ = -1.4357 × 10 ^-12
19th side K = -2.5267
A ₄ = 1.0222 × 10 ^-5 A ₆ = 5.0542 × 10 ^-8 A ₈ = -4.7099 × 10 ^-10
20th side K = -1.1009
A ₄ = 2.8262 × 10 ^-5 A ₆ = 2.5189 × 10 ^-8 A ₈ = -4.7553 × 10 ^-10
A ₁₀ = 0.0000 × 10 ⁰

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D8 4.55446 4.55446 4.55446
D12 28.71626 10.80422 1.26559
D23 31.30349 40.12841 49.10450

  FIG. 9 is a cross-sectional view along the optical axis showing the optical configuration of the zoom lens according to the fourth embodiment of the present invention, where (a) is the wide-angle end, (b) is the middle, and (c) is the telephoto end. Show. FIG. 10 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 4, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown.

  The zoom lens according to the fourth embodiment includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconvex lens L13 ″, and a biconcave lens L14 ′. It is composed of a biconcave lens L15 ′ and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a biconcave lens L22 ′ and a biconvex lens L23 ′, a biconvex lens L24, and a cemented lens of a biconcave lens L25 and a biconvex lens L26. It has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end is performed by fixing the second lens group G2 and moving the entire first lens group G1 integrally to the image side. It has become.
As for focusing, other moving methods such as moving a plurality of lens groups constituting the first lens group G1 or extending the entire zoom lens may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface facing the image side, the object side surface of the biconvex lens L21, and the object side surface of the biconcave lens L25.
Next, numerical data of optical members constituting the zoom lens of the fourth example are shown.

Numerical data 4
Wide angle end Medium telephoto end f 11.03 16 21.4
Fno. 2.84 3.16 3.54
2ω 90.6 ° 69.7 ° 55 °

r ₁ = 32.9626 d ₁ = 1.8 n _d1 = 1.788 ν _d1 = 47.37
r ₂ = 15.4644 d ₂ = 5.7694
r ₃ = 24.0647 d ₃ = 1.8 n _d3 = 1.8061 ν _d3 = 40.73
r ₄ = 11.4 (aspherical surface) d ₄ = 6.4527
r ₅ = 93.8265 d ₅ = 5.3657 n _d5 = 1.80518 ν _d5 = 25.42
r ₆ = -70.6964 d ₆ = 2.3869
r ₇ = -40.2675 d ₇ = 1 n _d7 = 1.8042 ν _d7 = 46.5
r ₈ = 44.7290 d ₈ = 2.6883
r ₉ = 35.4670 d ₉ = 3 n _d9 = 1.69895 ν _d9 = 30.13
r ₁₀ = -338.3015 d ₁₀ = D10
r ₁₁ = (aperture) d ₁₁ = 1
r ₁₂ = 28.7903 (aspherical surface) d ₁₂ = 3.5478 n _d12 = 1.7433 ν _d12 = 49.33
r ₁₃ = -37.5026 d ₁₃ = 3.5016
r ₁₄ = -27.9954 d ₁₄ = 3.8932 n _d14 = 1.804 ν _d14 = 46.57
r ₁₅ = 11.7093 d ₁₅ = 5.55 n _d15 = 1.48749 ν _d15 = 70.23
r ₁₆ = -153.6895 d ₁₆ = 0.1534
r ₁₇ = 19.2930 d ₁₇ = 7.3037 n _d17 = 1.57135 ν _d17 = 52.95
r ₁₈ = -18.9398 d ₁₈ = 0.1
r ₁₉ = -43.5264 (aspherical surface) d ₁₉ = 0.9 n _d19 = 1.8061 ν _d19 = 40.73
r ₂₀ = 14.1195 d ₂₀ = 7.4898 n _d20 = 1.48749 ν _d20 = 70.23
r ₂₁ = -19.0456 d ₂₁ = D21
r ₂₂ = ∞ d ₂₂ = 4.8 n _d22 = 1.54 ν _d24 = 63
r ₂₃ = ∞ d ₂₃ = 2
r ₂₄ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -0.6654
A ₄ = -1.1724 × 10 ^-5 A ₆ = -4.9913 × 10 ^-8 A ₈ = -1.5401 × 10 ^-10
A ₁₀ = -2.0568 × 10 ^-12
12th surface K = -1.0297
A ₄ = -5.4696 × 10 ^-6 A ₆ = 8.8924 × 10 ^-9 A ₈ = -7.5140 × 10 ^-10
A ₁₀ = 4.6863 × 10 ^-12
19th side K = 13.9303
A ₄ = -2.0674 × 10 ^-6 A ₆ = 1.1292 × 10 ^-7 A ₈ = 6.2119 × 10 ^-10
A ₁₀ = 2.9356 × 10 ^-12

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D10 25.00349 9.69634 1.12206
D21 29.39721 38.08129 47.54647
(When the object distance is 0.4m)
Surface interval Wide-angle end Medium telephoto end D10 26.59314 11.31564 2.75655

  11A and 11B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the fifth embodiment of the present invention. FIG. 11A shows a state at the wide-angle end, FIG. Show. FIG. 12 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 5, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown. FIG. 13 is a diagram showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 5 is focused at a shooting distance of 0.4 m, (a) is the wide-angle end, (b) is the middle, c) shows the state at the telephoto end.

  The zoom lens according to the fifth example includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface directed to the image side, a negative meniscus lens L12 having a concave surface directed to the image side, a biconcave lens L13, a biconvex lens L14, and an object side And a negative meniscus lens L15 having a concave surface directed toward the object side, and a positive meniscus lens L16 having a convex surface directed toward the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a concave surface directed toward the object side, and a biconcave lens L23, a biconvex lens L24, a biconcave lens L25, and a biconvex lens L26. And has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end moves the front group G1a of the first lens group G1 to the image side and moves the rear group G1b to the object side. To do.
For focusing, other moving methods such as moving the entire first lens group G1 integrally or moving only the rear group G1b may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface directed to the image side, and on both surfaces of the biconvex lens L24.
Next, numerical data of optical members constituting the zoom lens of the fifth example are shown.

Numerical data 5
Wide-angle end Middle Telephoto end f 11.25 16.09 21.59
Fno. 2.8500 3.1512 3.5064
2ω 93.4 ° 72.4 ° 56.9 °

r ₁ = 39.4656 d ₁ = 2.7000 n _d1 = 1.77250 ν _d1 = 49.60
r ₂ = 19.1575 d ₂ = 3.8376
r ₃ = 23.4988 d ₃ = 2.9000 n _d3 = 1.80610 ν _d3 = 40.92
r ₄ = 12.3518 (aspherical surface) d ₄ = 8.7545
r ₅ = −321.5338 d ₅ = 1.7500 n _d5 = 1.80440 ν _d5 = 39.59
r ₆ = 38.1909 d ₆ = 5.6587
r ₇ = 51.8517 d ₇ = 4.2500 n _d7 = 1.774077 ν _d7 = 27.79
r ₈ = -62.4189 d ₈ = D8
_{r 9 = -49.8100 d 9 = 1.7000} n d9 = 1.88300 ν d9 = 40.76
r ₁₀ = -634.3371 d ₁₀ = 0.1000
r ₁₁ = 76.0148 d ₁₁ = 2.8000 n _d11 = 1.78472 ν _d11 = 25.68
r ₁₂ = 279.3232 d ₁₂ = D12
r ₁₃ = (aperture) d ₁₃ = 1.000
r ₁₄ = 26.6837 d ₁₄ = 3.5381 n _d14 = 1.53172 ν _d14 = 48.84
r ₁₅ = -58.7525 d ₁₅ = 6.6753
r ₁₆ = −105.7861 d ₁₆ = 3.2705 n _d16 = 1.48749 ν _d16 = 70.23
r ₁₇ = -16.5092 d ₁₇ = 1.6600 n _d17 = 1.83481 ν _d17 = 42.72
r ₁₈ = 483.0727 d ₁₈ = 0.5116
r ₁₉ = 31.5949 (aspherical surface) d ₁₉ = 9.6340 n _d19 = 1.58913 ν _d19 = 61.14
r ₂₀ = -24.9249 (aspherical surface) d ₂₀ = 0.3176
r ₂₁ = -43.5703 d ₂₁ = 1.3700 n _d21 = 1.80440 ν _d21 = 39.59
r ₂₂ = 23.2096 d ₂₂ = 7.6628 n _d22 = 1.48749 ν _d22 = 70.23
r ₂₃ = -18.8170 d ₂₃ = D23
r ₂₄ = ∞ d ₂₄ = 4.6500 n _d24 = 1.51633 ν _d24 = 64.14
r ₂₅ = ∞ d ₂₅ = 1.000
r ₂₆ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -1.2568
A ₄ = 4.0845 × 10 ^-5 A ₆ = 7.9534 × 10 ^-9 A ₈ = 1.4928 × 10 ^-10
A ₁₀ = -6.6801 × 10 ^-13
19th side K = -2.9863
A ₄ = 6.2363 × 10 ^-9 A ₆ = 3.8233 × 10 ^-8 A ₈ = 2.5629 × 10 ^-10
A ₁₀ = -3.2996 × 10 ^-12
20th page K = -1.2082
A ₄ = 2.6128 × 10 ^-5 A ₆ = 2.9162 × 10 ^-8 A ₈ = -2.7710 × 10 ^-10
A ₁₀ = 0

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D8 3.67042 3.67042 3.67042
D12 30.02014 12.13323 1.54340
D23 30.83039 39.33862 49.00113
(When the object distance is 0.4m)
Surface interval Wide-angle end Medium telephoto end D8 1.05911 1.14556 1.15380
D12 32.41585 14.44961 3.85223

  14A and 14B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the sixth embodiment of the present invention. FIG. 14A shows the state at the wide-angle end, FIG. 14B shows the intermediate state, and FIG. Show. FIG. 15 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 6, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown.

  The zoom lens according to the sixth example includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, and a negative meniscus lens L13 ′ having a concave surface facing the image side. And a biconvex lens L14, a biconcave lens L15 ′, and a positive meniscus lens L16 having a convex surface facing the object side, and has a negative refractive power as a whole.

  The second lens group G2 includes, in order from the object side, a biconvex lens L21, a cemented lens of a positive meniscus lens L22 having a concave surface directed toward the object side, and a biconcave lens L23, a biconvex lens L24, a biconcave lens L25, and a biconvex lens L26. And has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end is performed by fixing the second lens group G2 and moving the entire first lens group G1 integrally to the image side. It has become.
As for focusing, other moving methods such as moving a plurality of lens groups constituting the first lens group G1 or extending the entire zoom lens may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface directed to the image side, and on both surfaces of the biconvex lens L24.
Next, numerical data of optical members constituting the zoom lens of the sixth example are shown.

Numerical data 6
Wide-angle end Middle Telephoto end f 11.08 16.08 21.17
Fno. 2.8500 3.16 3.49
2ω 90.3 ° 69.4 ° 55.5 °

r ₁ = 40.0655 d ₁ = 2.7 n _d1 = 1.7725 ν _d1 = 49.6
r ₂ = 17.5863 d ₂ = 6.612
r ₃ = 25.7506 d ₃ = 2.9 n _d3 = 1.8061 ν _d3 = 40.92
r ₄ = 12.0877 (aspherical surface) d ₄ = 10.3938
r ₅ = 76.6337 d ₅ = 1.6 n _d5 = 1.8044 ν _d5 = 39.59
r ₆ = 35.3282 d ₆ = 2.1363
r ₇ = 33.4764 d ₇ = 4.7115 n _d7 = 1.72825 ν _d7 = 28.46
r ₈ = -185.2077 d ₈ = D8
r ₉ = -89.4707 d ₉ = 1.5 n _d9 = 1.883 ν _d9 = 40.76
r ₁₀ = 75.9172 d ₁₀ = 0.291
r ₁₁ = 52.6242 d ₁₁ = 3 n _d11 = 1.76182 ν _d11 = 26.52
r ₁₂ = 441.0221 d ₁₂ = D12
r ₁₃ = (aperture) d ₁₃ = 1
r ₁₄ = 32.9566 d ₁₄ = 3.4867 n _d14 = 1.56732 ν _d14 = 42.82
r ₁₅ = −63.1956 d ₁₅ = 5.5488
r ₁₆ = 509.8453 d ₁₆ = 3.99566 n _d16 = 1.497 ν _d16 = 81.54
r ₁₇ = -18.2618 d ₁₇ = 1.7488 n _d17 = 1.804 ν _d17 = 46.57
r ₁₈ = 56.1153 d ₁₈ = 0.1174
r ₁₉ = 23.7029 (aspherical surface) d ₁₉ = 8.1876 n _d19 = 1.58313 ν _d19 = 59.38
r ₂₀ = -25.8538 (aspherical surface) d ₂₀ = 0.1076
r ₂₁ = -53.7863 d ₂₁ = 2.9145 n _d21 = 1.8061 ν _d21 = 40.92
r ₂₂ = 20.0996 d ₂₂ = 8.9527 n _d22 = 1.497 ν _d22 = 81.54
r ₂₃ = -19.0753 d ₂₃ = D23
r ₂₄ = ∞ d ₂₄ = 4.65 n _d24 = 1.51633 ν _d24 = 64.14
r ₂₅ = ∞ d ₂₅ = 1
r ₂₆ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -0.9686
A ₄ = 1.3528 × 10 ^-5 A ₆ = -2.1707 × 10 ^-8 A ₈ = 1.0537 × 10 ^-10
A ₁₀ = -1.4357 × 10 ^-12
19th side K = -2.5267
A ₄ = 1.0220 × 10 ^-5 A ₆ = 5.0542 × 10 ^-8 A ₈ = -4.7099 × 10 ^-10
20th side K = -1.1009
A ₄ = 2.8262 × 10 ^-5 A ₆ = 2.5189 × 10 ^-8 A ₈ = -4.7553 × 10 ^-10
A ₁₀ = 0

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D8 4.55446 4.55446 4.55446
D12 28.71626 10.80422 1.26559
D23 31.30349 40.12841 49.10450

  FIG. 16 is a cross-sectional view along the optical axis showing the optical configuration of the zoom lens according to the seventh embodiment of the present invention, where (a) is at the wide angle end, (b) is in the middle, and (c) is at the telephoto end. Show. FIG. 17 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 7, where (a) is the wide-angle end, (b) is the middle, and (c) is The state at the telephoto end is shown.

  The zoom lens according to the seventh example includes, in order from the object side, a first lens group G1, an aperture stop S, and a second lens group G2. In the figure, CG represents a low-pass filter, a near-infrared ray cut filter, and a CCD cover glass replaced with an equivalent parallel plate optical element. I represents the image plane.

  The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a concave surface facing the image side, a negative meniscus lens L12 having a concave surface facing the image side, a biconvex lens L13 ″, and a biconcave lens L14 ′. It is composed of a biconcave lens L15 ′ and has a negative refractive power as a whole.

  The second lens group G2, in order from the object side, includes a biconvex lens L21, a cemented lens of a biconcave lens L22 ′ and a biconvex lens L23 ′, a biconvex lens L24, and a cemented lens of a biconcave lens L25 and a biconvex lens L26. It has a positive refractive power as a whole.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, and the second lens group G2 moves to the object side together with the aperture stop S.
Further, focusing from infinity to the closest distance in any state from the wide-angle end to the telephoto end is performed by fixing the second lens group G2 and moving the entire first lens group G1 integrally to the image side. It has become.
As for focusing, other moving methods such as moving a plurality of lens groups constituting the first lens group G1 or extending the entire zoom lens may be used.

The aspheric surfaces are provided on the image side surface of the negative meniscus lens L12 having a concave surface facing the image side, the object side surface of the biconvex lens L21, and the object side surface of the biconcave lens L25.
Next, numerical data of optical members constituting the zoom lens of the seventh example are shown.

Numerical data 7
Wide angle end Medium telephoto end f 11.03 16 21.4
Fno. 2.84 3.16 3.54
2ω 90.6 ° 69.7 ° 55 °

r ₁ = 32.9626 d ₁ = 1.8 n _d1 = 1.788 ν _d1 = 47.37
r ₂ = 15.4644 d ₂ = 5.7694
r ₃ = 24.0647 d ₃ = 1.8 n _d3 = 1.8061 ν _d3 = 40.73
r ₄ = 11.4 (aspherical surface) d ₄ = 6.4527
r ₅ = 93.8265 d ₅ = 5.3657 n _d5 = 1.80518 ν _d5 = 25.42
r ₆ = -70.6964 d ₆ = 2.3869
r ₇ = -40.2675 d ₇ = 1 n _d7 = 1.8042 ν _d7 = 46.5
r ₈ = 44.7290 d ₈ = 2.6883
r ₉ = 35.4670 d ₉ = 3 n _d9 = 1.69895 ν _d9 = 30.13
r ₁₀ = -338.3015 d ₁₀ = D10
r ₁₁ = (aperture) d ₁₁ = 1
r ₁₂ = 28.7903 (aspherical surface) d ₁₂ = 3.5478 n _d12 = 1.7433 ν _d12 = 49.33
r ₁₃ = -37.5026 d ₁₃ = 3.5016
r ₁₄ = -27.9954 d ₁₄ = 3.8932 n _d14 = 1.804 ν _d14 = 46.57
r ₁₅ = 11.7093 d ₁₅ = 5.55 n _d15 = 1.48749 ν _d15 = 70.23
r ₁₆ = -153.6895 d ₁₆ = 0.1534
r ₁₇ = 19.2930 d ₁₇ = 7.3037 n _d17 = 1.57135 ν _d17 = 52.95
r ₁₈ = -18.9398 d ₁₈ = 0.1
r ₁₉ = -43.5264 (aspherical surface) d ₁₉ = 0.9 n _d19 = 1.8061 ν _d19 = 40.73
r ₂₀ = 14.1195 d ₂₀ = 7.4898 n _d20 = 1.48749 ν _d20 = 70.23
r ₂₁ = -19.0456 d ₂₁ = D21
r ₂₂ = ∞ d ₂₂ = 4.8 n _d22 = 1.54 ν _d24 = 63
r ₂₃ = ∞ d ₂₃ = 2
r ₂₄ = ∞ (image plane) d ₂₆ = 0

Aspheric data 4th surface K = -0.6654
A ₄ = -1.1724 × 10 ^-5 A ₆ = -4.9913 × 10 ^-8 A ₈ = -1.5401 × 10 ^-10
A ₁₀ = -2.0568 × 10 ^-12
12th surface K = -1.0297
A ₄ = -5.4696 × 10 ^-6 A ₆ = 8.8924 × 10 ^-9 A ₈ = -7.5140 × 10 ^-10
A ₁₀ = 4.6863 × 10 ^-12
19th side K = 13.9303
A ₄ = -2.0674 × 10 ^-6 A ₆ = 1.1292 × 10 ^-7 A ₈ = 6.2119 × 10 ^-10
A ₁₀ = -2.9356 × 10 ^-12

Zoom data (when focusing on an object point at infinity)
Surface spacing Wide-angle end Middle telephoto end D10 25.00349 9.69634 1.12206
D21 29.39721 38.08129 47.54647
(When the object distance is 0.4m)
Surface interval Wide-angle end Medium telephoto end D10 26.59314 11.31564 2.75655

Next, Table 1 shows the conditional expression parameter values in the zoom lenses of the above embodiments.
Table 1

  The zoom lens of the present invention described above can be applied to a silver salt or digital single-lens reflex camera. These are exemplified below.

  FIG. 18 is a cross-sectional view of a single-lens reflex camera using the zoom lens of the present invention as a photographing lens and using a small CCD or C-MOS as an image sensor. In FIG. 18, 1 is a single-lens reflex camera, 2 is a photographic lens, 3 is a mount part that allows the photographic lens 2 to be attached to and detached from the single-lens reflex camera 1, and a screw-type mount, bayonet-type mount, or the like is used. . In this example, a bayonet type mount is used. Reference numeral 4 denotes an image pickup element surface, 5 denotes a quick return mirror disposed between the lens system on the optical path 6 of the photographing lens 2 and the image pickup element surface 4, and 7 denotes an optical path reflected from the quick return mirror. A finder screen, 8 is a pentaprism, 9 is a finder, and E is an observer's eye (eye point). As the photographic lens 2 of the single-lens reflex camera 1 having such a configuration, for example, the zoom lens of the present invention shown in the first to seventh embodiments is used.

1 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to a first embodiment of the present invention, where (a) shows a state at a wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 4 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to the first example, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 4 is a diagram showing spherical aberration, astigmatism, and distortion when the zoom lens according to the first embodiment has a focal length of 0.4 m, (a) is a wide angle end, (b) is an intermediate, and (c) is The state at the telephoto end is shown. FIG. 4 is a cross-sectional view along the optical axis showing the optical configuration of a zoom lens according to a second embodiment of the present invention, where (a) shows the wide-angle end, (b) the middle, and (c) the telephoto end. . FIG. 6 is a diagram illustrating spherical aberration, astigmatism, and distortion at the infinite focal point of the zoom lens according to the second example, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion when the zoom lens according to Example 2 is focused at a shooting distance of 0.4 m, where (a) is a wide angle end, (b) is an intermediate, and (c) is The state at the telephoto end is shown. FIG. 4 is a cross-sectional view along the optical axis showing the optical configuration of a zoom lens according to a third embodiment of the present invention, where (a) shows a state at the wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 3, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 6 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to a fourth embodiment of the present invention, where (a) shows a state at a wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 6 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 4, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 6 is a cross-sectional view taken along an optical axis showing an optical configuration of a zoom lens according to a fifth embodiment of the present invention, where (a) shows a state at a wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 7 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 5, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 7 is a diagram illustrating spherical aberration, astigmatism, and distortion when the zoom lens according to Example 5 is focused at a shooting distance of 0.4 m, where (a) is a wide angle end, (b) is an intermediate, and (c) is The state at the telephoto end is shown. FIG. 6 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to a sixth embodiment of the present invention, where (a) shows a state at a wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 10 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 6, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. FIG. 10 is a cross-sectional view along an optical axis showing an optical configuration of a zoom lens according to Example 7 of the present invention, where (a) shows a state at a wide angle end, (b) shows an intermediate state, and (c) shows a state at a telephoto end. . FIG. 7 is a diagram showing spherical aberration, astigmatism, and distortion at the infinity focal point of the zoom lens according to Example 7, where (a) is a wide angle end, (b) is an intermediate end, and (c) is a telephoto end. Shows the state. 1 is a cross-sectional view of a single-lens reflex camera using a zoom lens of the present invention as a photographing lens and using a small CCD or C-MOS as an image sensor. FIG.

Explanation of symbols

G1 First lens group G1a Front group G1b Rear group G2 Second lens group L11, L12, L13 ′ Negative meniscus lenses L13, L14 ′, L15 ′, L22 ′, L23, L25 biconcave lenses L13 ″ with the concave surface facing the image side , L14, L21, L23 ′, L24, L26 Biconvex lens L15 Negative meniscus lens L16 with a concave surface facing the object side L16 Positive meniscus lens L with a convex surface facing the object side L22 Positive meniscus lens S with a concave surface facing the object side CG Parallel plate I Image plane 1 Single-lens reflex camera 2 Shooting lens 3 Mount unit 4 Image sensor surface 5 Quick return mirror 6 Optical path 7 Viewfinder screen 8 arranged in the optical path reflected from the quick return mirror 8 Penta prism 9 Viewfinder E Observer Eye (eye point)

Claims (38)

In order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, a zoom lens that performs zooming by varying the interval of at least two groups,
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a positive lens. A biconvex fourth lens having a refractive power of 5; a fifth lens having a negative refractive power; and a biconvex sixth lens having a positive refractive power;
A zoom lens satisfying the following conditional expression:
0.07 <d12 / f2G <0.30
However, d12 is an air distance on the optical axis which is sandwiched between the second lens and the front Symbol first lens, is f2G a focal length of the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied .
0.07 <d12 / f2G <0.17
However, d12 is the air space on the optical axis between the first lens and the second lens, and f2G is the focal length of the second lens group. The zoom lens according to claim 1, wherein the second lens and the third lens are cemented, and the fifth lens and the sixth lens are cemented . A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
The second lens and the third lens are cemented, the fifth lens and the sixth lens are cemented,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G < 0.17
However, d12 is an air distance on the optical axis which is sandwiched between the second lens and the front Symbol first lens, is f2G a focal length of the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.5 <f1 / f2G <1.0
Where f1 is the focal length of the first lens, and f2G is the focal length of the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied .
−1.0 <f23 / f2G <−0.4
Here, f23 is a combined focal length of the second lens and the third lens, and f2G is a focal length of the second lens group. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
−1.0 <f23 / f2G <−0.4
However, d12 is the air space on the optical axis sandwiched between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance. The zoom lens according to claim 1 , wherein the following conditional expression is satisfied .
−0.5 <f2G / f56 <0
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.15 <d12 / f2G <0.25
Here, d12 is an air interval on the optical axis between the first lens and the second lens, and f2G is a focal length of the second lens group. The second lens has a positive refractive power, Zumuren's of claim 9, wherein the third lens is characterized by having a negative refractive power. Said second lens and said third lens are bonded, Zumuren's of claim 9 or 10 wherein the fifth lens and said sixth lens is characterized in that it is joined. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
In order from the object side, the second lens group includes a biconvex first lens having a positive refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a positive lens. A biconvex fourth lens having a refractive power of 5; a fifth lens having a negative refractive power; and a biconvex sixth lens having a positive refractive power;
The second lens and the third lens are cemented, the fifth lens and the sixth lens are cemented,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
Here, d12 is an air interval on the optical axis between the first lens and the second lens, and f2G is a focal length of the second lens group. The zoom lens according to claim 9 , wherein the following conditional expression is satisfied.
0.8 <f1 / f2G <1.5
Where f1 is the focal length of the first lens, and f2G is the focal length of the second lens group. The zoom lens according to claim 9 , wherein the following conditional expression is satisfied.
−1.5 <f23 / f2G <−0.8
Where f23 is the combined focal length of the second lens and the third lens, and f2G is the focal length of the second lens group. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
−1.5 <f23 / f2G <−0.8
Where d12 is the air spacing on the optical axis between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance . The zoom lens according to claim 9, wherein the following conditional expression is satisfied.
−0.1 <f2G / f56 <0.05
Here , f 2G is the focal length of the second lens group , and f 56 is the combined focal length of the fifth lens and the sixth lens . The fourth lens, Zumuren's according to any one of claims 3,4,9～12 which is a single lens having at least one aspherical surface. The zoom lens according to any one of claims 1 to 4 , 9 to 12 , and 17 , wherein the following conditional expression is satisfied.
0.5 <f1 / f2G <2.0
However, f1 represents a focal length of the first lens, f2G is the focal length of the second lens group. The zoom lens according to any one of claims 1 to 5 , 9 to 13 , 17 , and 18 , wherein the following conditional expression is satisfied.
−2.0 <f23 / f2G <−0.4
However, f23 is the composite focal length of the third lens and the second lens, f2G is the focal length of the second lens group. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
−2.0 <f23 / f2G <−0.4
However, d12 is the air space on the optical axis sandwiched between the first lens and the second lens, f2G is the focal length of the second lens group, and f23 is the combined focus of the second lens and the third lens. Distance . The zoom lens according to any one of claims 1 to 7, 9 to 15, and 17 to 20, wherein the following conditional expression is satisfied.
0.4 <f4 / f2G <1.5
Here, f4 is the focal length of the fourth lens, and f2G is the focal length of the second lens group . The zoom lens according to claim 21 , wherein the following conditional expression is satisfied.
0.5 <f4 / f2G <1.0
Here, f4 is the focal length of the fourth lens, and f2G is the focal length of the second lens group . A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing at least the distance between the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
0.5 <f4 / f2G <1.0
Here, d12 is an air interval on the optical axis between the first lens and the second lens, f2G is a focal length of the second lens group, and f4 is a focal length of the fourth lens . The first lens group includes a plurality of negative lenses having a concave surface on the image plane side, a positive lens, a negative lens, and a positive lens in order from the object side. Zumuren's crab described. A zoom lens that includes, in order from the object side, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and performing zooming by changing the distance between at least the two groups.
An aperture stop is disposed between the first lens group and the second lens group,
The first lens group includes, in order from the object side, a plurality of negative lenses having a concave surface on the image plane side, a positive lens, a negative lens, and a positive lens.
The second lens group includes, in order from the object side, a biconvex first lens having a positive refractive power, a second lens having a positive or negative refractive power, and a refraction having a sign different from that of the second lens. A third lens having power, a biconvex fourth lens having positive refractive power, a fifth lens having negative refractive power, and a biconvex sixth lens having positive refractive power ,
Characterized by satisfying the following condition and to Luz Murenzu.
0.07 <d12 / f2G <0.30
Here, d12 is an air interval on the optical axis between the first lens and the second lens, and f2G is a focal length of the second lens group . 26. The zoom lens according to claim 24, wherein two negative lenses on the object side of the plurality of negative lenses are configured as negative meniscus lenses. 27. The zoom lens according to claim 24, wherein the positive lens disposed following the plurality of negative lenses is formed in a biconvex shape . 28. The zoom lens according to claim 21, wherein the second lens has a positive refractive power, and the third lens has a negative refractive power . The zoom lens according to claim 1, wherein the following conditional expression is satisfied .
−0.5 <f2G / f56 <0.1
Here, f2G is a focal length of the second lens group, and f56 is a combined focal length of the fifth lens and the sixth lens. 30. The zoom lens according to claim 1, wherein the following conditional expression is satisfied .
0.8 <GD26 / SD26 <1
However, GD26 is the total thickness on the optical axis of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, and SD26 is from the object side surface of the second lens. It is the length on the optical axis to the image side surface of the sixth lens. The zoom lens according to claim 30 , wherein the following conditional expression is satisfied .
0.9 <GD26 / SD26 <1
However, GD26 is the total thickness on the optical axis of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, and SD26 is from the object side surface of the second lens. It is the length on the optical axis to the image side surface of the sixth lens . The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.4 <SD26 / f2G <1
Where SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens, and f2G is the focal length of the second lens group. The zoom lens according to claim 32, wherein the following conditional expression is satisfied.
0.5 <SD26 / f2G <0.9
Where SD26 is the length on the optical axis from the object side surface of the second lens to the image side surface of the sixth lens, and f2G is the focal length of the second lens group. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1 <| f1G | / DS <3
  Where f1G is the focal length of the first lens group, and DS is the first lens group and the second lens when the focal length of the entire zoom lens system is -0.8 times the focal length of the first lens group. This is the lens surface distance between the lens groups. The zoom lens according to claim 34, wherein the following conditional expression is satisfied.
1.2 <| f1G | / DS <2
Where f1G is the focal length of the first lens group, and DS is the first lens group and the second lens when the focal length of the entire zoom lens system is -0.8 times the focal length of the first lens group. This is the lens surface distance between the lens groups. The zoom lens according to any one of claims 1 to 35, wherein the zoom lens is configured to form an image in a region where the total angle of view at the wide angle end is 90 ° or more. The zoom lens according to any one of claims 1 to 36, wherein the zoom lens is configured as a two-group zoom lens having only two lens groups that move during zooming. A camera using the zoom lens according to claim 1.