JP6549762B2 - Zoom lens - Google Patents

Description

  The present invention relates to a zoom lens suitable for a small-sized imaging apparatus on which a solid-state imaging device such as a CCD or a CMOS is mounted.

  Imaging devices such as single-lens reflex cameras, digital still cameras, video cameras, surveillance cameras, etc., on which solid-state imaging devices such as CCDs and COMS are mounted are rapidly spreading. In connection with this, many zoom lenses which can be used for an imaging device in which solid imaging elements, such as CCD and CMOS, were carried are proposed (for example, refer to patent documents 1-3.).

JP 2012-22080 A JP, 2012-168513, A Patent No. 4283553

  In recent years, with the progress of increasing the number of pixels and increasing the sensitivity of solid-state imaging devices, high optical performance is also required for imaging lenses. In addition, as miniaturization of imaging devices advances, downsizing and weight reduction of photographing lenses are also desired. Furthermore, there is also a demand for zoom lenses with high magnification that correspond to light from the visible light range to the near infrared range so that they can be used in various applications such as surveillance cameras and in-vehicle cameras.

  The zoom lenses described in Patent Documents 1 and 2 are zoom lenses having a simple lens group configuration in which lens groups having negative, positive, and positive refractive power are arranged in order from the object side. However, in these zoom lenses, since the number of lenses in the first lens group and the third lens group is small and it is difficult to suppress various aberrations generated in each lens group, a good image can not be obtained. This problem is more pronounced in higher magnification images. Further, for near infrared light, axial chromatic aberration and magnification chromatic aberration generated at the telephoto end become remarkable, and there is a problem that optical performance for near infrared light is significantly deteriorated.

  In the zoom lens described in Patent Document 3, aberration correction is performed on light from the visible light range to the near infrared range at high magnification. However, since the first lens group has a positive refracting power, the overall optical system tends to be large when attempting to increase the aperture ratio, making it difficult to achieve both the large aperture ratio and the miniaturization. There is a problem of being

  SUMMARY OF THE INVENTION The present invention is to provide a compact zoom lens with high optical performance capable of satisfactorily correcting various aberrations over the entire variable power range in order to solve the above-mentioned problems of the prior art. To aim.

In order to solve the problems described above and achieve the object, the zoom lens according to the present invention comprises a first lens group having negative refractive power and a second lens having positive refractive power, which are disposed in order from the object side. A zoom lens including a group and a third lens group and changing magnification on the optical axis of each lens group, wherein the second lens group is disposed in order from the object side The third lens group is composed of a positive lens, a negative lens, and a positive lens, and the third lens group is configured such that the negative lens is disposed closest to the object side, and the following conditional expression is satisfied. Do.
(1) 2.8 ≦ | β2T / β2W | ≦ 12.0
Here, β2T represents the magnification of the second lens group at the telephoto end, and β2W represents the magnification of the second lens group at the wide angle end.

  According to the present invention, it is possible to provide a compact zoom lens with high optical performance that can correct various aberrations well over the entire variable power range.

  Furthermore, in the zoom lens according to the present invention, in the above-mentioned invention, zooming is performed by moving the first lens group along the optical axis, and the lens groups after the second lens group are moved along the optical axis To correct the image plane variation caused by the magnification change, and move the first lens unit to the object side along the optical axis, from an infinite distance object focusing state to a closest distance object focusing state Focusing is performed.

  According to the present invention, it is possible to suppress image plane fluctuation at the time of zooming and focusing, and to maintain good optical performance.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(2)-0.5 β β 2 W −-0.1
Here, β2W indicates the magnification of the second lens group at the wide-angle end.

  According to the present invention, it is possible to realize a compact zoom lens having high optical performance by suppressing coma and field curvature generated in the second lens group at the wide angle end.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(3) −4.50 ≦ β2T ≦ −1.45
Here, β2T represents the magnification of the second lens group at the telephoto end.

  According to the present invention, it is possible to realize a compact zoom lens having high optical performance by suppressing coma aberration and field curvature generated in the second lens group at the telephoto end.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(4) 0.3 ≦ βLT ≦ 1.0
Here, βLT represents the magnification at the telephoto end of the lens unit disposed closest to the image side.

  According to the present invention, it is possible to realize a compact zoom lens having high optical performance by suppressing spherical aberration and field curvature generated in the lens unit disposed closest to the image side at the telephoto end.

  Furthermore, in the zoom lens according to the present invention, in the above-mentioned invention, the second lens unit includes an aperture stop that defines a predetermined aperture, and the second aperture stop is the second aperture stop when zooming from the wide angle end to the telephoto end. It is characterized in that it moves from the image side to the object side together with the lens unit.

  According to the present invention, it is possible to provide a compact, large aperture, high magnification zoom lens.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(5) 0.35 ≦ | f1 | /f2≦0.85
Here, f1 represents the focal length of the first lens group, and f2 represents the focal length of the second lens group.

  According to the present invention, spherical aberration and field curvature generated in the first lens group can be appropriately corrected by the second lens group, and high optical performance can be obtained.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(6) 0.2 ≦ | f2 / f3 | ≦ 1.0
Here, f2 represents the focal length of the second lens group, and f3 represents the focal length of the third lens group.

  According to the present invention, coma aberration and field curvature generated in the second lens group can be appropriately corrected by the third lens group, and high optical performance can be obtained.

Further, in the zoom lens according to the present invention, in the above-mentioned invention, the first lens group includes at least one positive lens and one negative lens, and the conditional expression shown below is satisfied. It features.
(7) d d 1 p ≦ 41.0
(8) d d1 n 5 50.0
Here, dd1p represents the Abbe number of the positive lens to the d-line included in the first lens group, and dd1n represents the Abbe number of the negative lens to the d-line included in the first lens group.

  According to the present invention, it is possible to satisfactorily correct the chromatic aberration generated by the negative lens included in the first lens group, and also favorably correct the spherical aberration and the curvature of field, to obtain high optical performance. In particular, aberrations generated for light in the visible light region to the near infrared region can be well corrected.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(9) d d 2 pa 6 68.0
Here, ν d 2 pa represents the average value of Abbe numbers for the d-line of the positive lens included in the second lens group.

  According to the present invention, it is possible to satisfactorily correct the chromatic aberration to the light in the visible light region to the near infrared region, which is generated in the second lens group, and to obtain high optical performance.

  Furthermore, in the zoom lens according to the present invention, in the above-mentioned invention, the first lens group is characterized in that a negative lens, a negative lens, and a positive lens are sequentially arranged in order from the object side. I assume.

  According to the present invention, various aberrations generated in the first lens group can be suppressed.

  Furthermore, the zoom lens according to the present invention is characterized in that, in the above-mentioned present invention, the third lens group is configured such that a negative lens and a positive lens are sequentially arranged in order from the object side.

  According to the present invention, it is possible to correct curvature of field and coma aberration generated in the first and second lens units with the third lens unit.

Furthermore, in the zoom lens according to the present invention, in the above-mentioned invention, the negative lens disposed on the most object side of the third lens group has a concave surface facing the object side, and the conditional expression shown below is satisfied. It features.
(10)-1.5 <(R31 + R32) / (R31-R32) <0.3
However, R31 is the curvature radius of the object side surface of the negative lens disposed on the most object side of the third lens group, and R32 is the curvature of the image side surface of the negative lens disposed on the most object side of the third lens group Indicates the radius.

  According to the present invention, it is possible to satisfactorily correct the curvature of field generated in the first and second lens groups with the third lens group.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(11) 4.5 ≦ | X2 | ² /(|f1|×f2)≦16.5
Here, X2 indicates the amount of movement of the second lens unit during zooming from the wide-angle end to the telephoto end, f1 indicates the focal length of the first lens unit, and f2 indicates the focal length of the second lens unit.

  The amount of movement X2 of the second lens group means the point on the optical axis of the second lens group when the second lens group moves from the wide-angle end to the telephoto end with respect to one point fixed within a finite distance on the optical axis. The amount of movement of

  According to the present invention, it is possible to appropriately set the moving amount of the second lens group at the time of zooming from the wide-angle end to the telephoto end, and to shorten the entire length of the optical system while maintaining the optical performance.

Further, the zoom lens according to the present invention is characterized in that, in the above-mentioned invention, the conditional expression shown below is satisfied.
(12) 0.3 ≦ f2 / fLw ≦ 1.1
Here, f2 represents the focal length of the second lens group, and fLw represents the combined focal length at the wide-angle end of all the lens groups disposed after the third lens group.

  According to the present invention, the coma aberration generated in the second lens unit at the wide angle end can be corrected well by the third lens unit and the subsequent lens units.

  According to the present invention, there is provided a zoom lens having a small size and high optical performance capable of satisfactorily correcting various aberrations (in particular, curvature of field, coma and spherical aberration) over the entire zoom range. It has the effect of being able to

FIG. 1 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to Example 1. 5 is a diagram showing various aberrations of the zoom lens according to Example 1. FIG. FIG. 5 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to Example 2. FIG. 6 shows various aberrations that occurred in the zoom lens according to Example 2. FIG. 7 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to Example 3. FIG. 6 shows various aberrations that occurred in the zoom lens according to Example 3. FIG. 10 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to Example 4. FIG. 7 shows various aberrations that occurred in the zoom lens according to Example 4. FIG. 10 is a cross-sectional view along an optical axis showing the configuration of a zoom lens according to Example 5. FIG. 7 shows various aberrations that occurred in the zoom lens of the fifth example. FIG. 16 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to Example 6. FIG. 6 shows various aberrations that occurred in the zoom lens according to Example 6. FIG. 14 is a cross-sectional view along an optical axis showing the configuration of the zoom lens according to Example 7; FIG. 7 shows various aberrations that occurred in the zoom lens according to Example 7.

  Hereinafter, preferred embodiments of the zoom lens according to the present invention will be described in detail.

  The zoom lens according to the present invention includes a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group, which are disposed in order from the object side. Be done. Then, the magnification change is performed by changing the distance on the optical axis of each lens unit.

  It is an object of the present invention to provide a compact zoom lens with high optical performance that can correct various aberrations well over the entire variable power range. Therefore, in order to achieve the above purpose, various conditions as shown below are set.

  In order to realize a zoom lens having a small size and high optical performance, it is desirable to increase the refractive power of a lens group that controls zooming and to reduce the amount of movement associated with zooming. However, as the refractive power increases, the amount of aberration generation tends to increase, and it becomes difficult to maintain high optical performance. For this reason, in order to realize a compact zoom lens with high optical performance, it is possible to appropriately set the lens configuration of the lens unit that controls zooming, and the magnification of each lens unit at the wide-angle end and the telephoto end. It will be necessary.

  In the zoom lens according to the present invention, the second lens group is composed of a positive lens, a negative lens, and a positive lens, which are disposed in order from the object side. In the second lens group, spherical aberration, curvature of field, and chromatic aberration generated by the positive lens disposed closest to the object side are corrected by the negative lens and the positive lens disposed subsequent to the positive lens. Further, in the second lens group, by disposing the positive lens closest to the object side, the incident light beam can be converged by the positive lens, and the diameter reduction of the second lens group and thereafter can be achieved.

  The third lens group is configured such that a negative lens is disposed closest to the object side. By diverging the light beam incident in the vicinity of the optical axis by the negative lens, the field curvature at the telephoto end can be corrected well.

In the zoom lens according to the present invention, assuming that the magnification at the telephoto end of the second lens group is β2T and the magnification at the wide angle end of the second lens group is β2W on the premise of the above configuration, the following conditional expression is satisfied. Is preferred.
(1) 2.8 ≦ | β2T / β2W | ≦ 12.0

  Conditional expression (1) defines the ratio of the magnification at the telephoto end of the second lens unit to the magnification at the wide angle end. By satisfying the conditional expression (1), it is possible to miniaturize the optical system (shorten the overall length of the optical system) and to suppress the occurrence of curvature of field upon zooming from the wide-angle end to the telephoto end. High optical performance can be maintained over the doubling range.

  If the lower limit value in conditional expression (1) is exceeded, the contribution of the second lens unit to zooming becomes too large, so field curvature that occurs with zooming becomes large, making correction difficult. On the other hand, if the upper limit value in conditional expression (1) is exceeded, the contribution of the second lens unit to the zooming becomes small, so the moving amount of the second lens unit at the time of zooming increases and the overall length of the optical system is shortened. Will be difficult.

When the conditional expression (1) satisfies the following range, more preferable effects can be expected.
(1a) 4.0 ≦ | β2T / β2W | ≦ 10.9
By satisfying the range defined by the conditional expression (1a), it is possible to realize a zoom lens having a smaller size and high optical performance.

In addition, when the conditional expression (1a) satisfies the following range, it is possible to realize a further compact zoom lens with high optical performance.
(1b) 5.0 ≦ | β2T / β2W | ≦ 9.8

  In the zoom lens according to the present invention, zooming is performed by moving the first lens group along the optical axis, and zooming is performed by moving the lens groups after the second lens group along the optical axis. It is recommended that focusing from an infinite distance object focusing state to a closest distance distance object focusing state be performed by correcting the image plane fluctuation accompanying the lens and moving the first lens unit to the object side along the optical axis. .

  The image plane variation can be efficiently corrected by mainly providing the first lens unit with a variable magnification function and making the lens units after the second lens unit carry out correction of the image plane variation accompanying the magnification change. Further, by causing the first lens group to perform focusing, it is possible to suppress the image plane fluctuation associated with focusing and to maintain good optical performance.

Furthermore, in the zoom lens according to the present invention, it is preferable to satisfy the following conditional expression when the magnification of the second lens group at the wide angle end is β2W.
(2)-0.5 β β 2 W −-0.1

  Conditional expression (2) defines the magnification of the second lens unit at the wide-angle end. By satisfying the conditional expression (2), it is possible to suppress coma aberration and field curvature generated in the second lens group at the wide angle end, and to realize a compact zoom lens having high optical performance.

  If the lower limit value in conditional expression (2) is exceeded, the refractive power of the second lens unit becomes too weak, and the overall length of the optical system is extended, making it difficult to miniaturize the optical system. On the other hand, if the upper limit value in conditional expression (2) is exceeded, the refractive power of the second lens unit becomes too strong, which makes it difficult to correct coma and field curvature that occur at the wide-angle end.

When the conditional expression (2) satisfies the range shown below, more preferable effects can be expected.
(2a) −0.45 ≦ β2W ≦ −0.15
By satisfying the range defined by the conditional expression (2a), it is possible to realize a zoom lens having a smaller size and high optical performance.

In addition, when the conditional expression (2a) satisfies the following range, it is possible to realize a zoom lens that is smaller and has high optical performance.
(2b)-0.3 β β 2 W −-0.2

Furthermore, in the zoom lens according to the present invention, it is preferable that the following conditional expression be satisfied, where β2T is a magnification of the second lens group at the telephoto end.
(3) −4.50 ≦ β2T ≦ −1.45

  Conditional expression (3) defines the magnification of the second lens unit at the telephoto end. By satisfying the conditional expression (3), it is possible to suppress a coma aberration and a field curvature generated in the second lens unit at the telephoto end, and to realize a compact zoom lens having high optical performance.

  If the lower limit value in conditional expression (3) is exceeded, the refractive power of the second lens unit will be too weak, and the overall length of the optical system will extend, making it difficult to miniaturize the optical system. On the other hand, if the upper limit value is exceeded in the conditional expression (3), the refractive power of the second lens unit becomes too strong, which makes it difficult to correct coma aberration and field curvature generated at the telephoto end.

When the conditional expression (3) satisfies the following range, more preferable effects can be expected.
(3a) −4.0 ≦ β2T ≦ −2.0
By satisfying the range defined by the conditional expression (3a), it is possible to realize a zoom lens having a smaller size and high optical performance.

In addition, when the conditional expression (3a) satisfies the following range, it is possible to realize a further compact zoom lens with high optical performance.
(3b)-3.5 β β 2 T −-2.5

Furthermore, in the zoom lens according to the present invention, it is preferable to satisfy the following conditional expression when the magnification at the telephoto end of the lens unit disposed closest to the image side is βLT.
(4) 0.3 ≦ βLT ≦ 1.0

  The conditional expression (4) defines the magnification at the telephoto end of the lens unit which is disposed closest to the image. By satisfying the conditional expression (4), it is possible to suppress the spherical aberration and the field curvature generated in the lens unit disposed closest to the image side at the telephoto end, and realize the zoom lens having a small size and high optical performance. can do.

  If the lower limit value in conditional expression (4) is exceeded, the refractive power of the lens unit arranged closest to the image side becomes too strong, and it becomes difficult to correct spherical aberration and field curvature generated at the telephoto end. On the other hand, if the upper limit value is exceeded in conditional expression (4), the refractive power of the lens unit disposed closest to the image side becomes too weak, the entire length of the optical system is extended, and miniaturization of the optical system becomes difficult .

When the conditional expression (4) satisfies the range shown below, more preferable effects can be expected.
(4a) 0.4 ≦ βLT ≦ 0.9
By satisfying the range defined by the conditional expression (4a), it is possible to realize a zoom lens having a smaller size and high optical performance.

In addition, when the conditional expression (4a) satisfies the following range, it is possible to realize a zoom lens that is smaller and has high optical performance.
(4b) 0.5 ≦ βLT ≦ 0.8

  Another object of the present invention is to provide a compact, large aperture, high magnification zoom lens. Therefore, in order to achieve the above purpose, the following configuration is employed.

  That is, in the zoom lens according to the present invention, the second lens unit is provided with an aperture stop that defines a predetermined aperture, and upon zooming from the wide-angle end to the telephoto end, both the aperture stop and the second lens unit are objects from the image side Move to the side.

  In order to realize a bright optical system, it is necessary to increase the aperture diameter of the aperture stop. However, increasing the aperture diameter affects the outer diameter of the optical system to construct a small-diameter optical system. Will be difficult. In the zoom lens according to the present invention, as described above, the positive lens is disposed on the most object side of the second lens group, and the incident light beam is converged by the positive lens to reduce the diameter of the second lens group and thereafter. There is. Therefore, in the zoom lens according to the present invention, by providing the aperture stop in the second lens group, it is possible to realize a bright optical system without enlarging the outer diameter of the optical system.

  In addition, when the aperture stop is fixed, the aperture stop interferes during zooming to restrict the amount of movement of each lens unit, which makes it difficult to achieve high magnification and also makes aberration correction difficult. If a zoom lens with high optical power and good optical performance is to be realized with the aperture stop fixed, it is necessary to secure a moving area of each lens unit with a margin, and the optical system becomes larger The problem of causing (the length of the optical system increases) occurs. Therefore, in the zoom lens according to the present invention, the aperture stop is disposed in the second lens unit, and the aperture stop moves together with the second lens unit at the time of zooming, even if the area is limited. The moving amount of each lens group can be secured, and optical performance can be improved along with downsizing and high magnification.

Furthermore, in the zoom lens according to the present invention, it is preferable to satisfy the following conditional expression, where f1 is the focal length of the first lens group and f2 is the focal length of the second lens group.
(5) 0.35 ≦ | f1 | /f2≦0.85

  Conditional expression (5) defines the ratio of the focal length of the first lens unit to the focal length of the second lens unit. By satisfying conditional expression (5), spherical aberration and field curvature generated in the first lens group can be appropriately corrected by the second lens group, and high optical performance can be obtained.

  If the lower limit value in conditional expression (5) is exceeded, the refractive power of the first lens group becomes too strong, so the field curvature generated in the first lens group becomes too large, and the field curvature in the second lens group Can not be corrected. On the other hand, if conditional expression (5) exceeds the upper limit value, the refractive power of the second lens group becomes too strong, so that correction of spherical aberration generated in the first lens group becomes excessive, resulting in high optical performance. It will be difficult to get

When the conditional expression (5) satisfies the range shown below, more preferable effects can be expected.
(5a) 0.4 ≦ | f1 | /f2≦0.7
By satisfying the range defined by the conditional expression (5a), a zoom lens having higher optical performance can be realized.

Further, when the conditional expression (5a) satisfies the following range, it is possible to realize a zoom lens having higher optical performance.
(5b) 0.5 ≦ | f1 | /f2≦0.7

Furthermore, in the zoom lens according to the present invention, it is preferable to satisfy the following conditional expression, where f2 is the focal length of the second lens group and f3 is the focal length of the third lens group.
(6) 0.2 ≦ | f2 / f3 | ≦ 1.0

  Conditional expression (6) defines the ratio of the focal length of the second lens unit to the focal length of the third lens unit. By satisfying the conditional expression (6), it is possible to appropriately correct the comatic aberration and the curvature of field generated in the second lens unit by the third lens unit, and it is possible to obtain high optical performance.

  If the lower limit value in conditional expression (6) is exceeded, the refracting power of the third lens unit becomes too strong, and it becomes impossible to correct the field curvature appropriately. On the other hand, if the upper limit value in conditional expression (6) is exceeded, the refractive power of the second lens unit becomes too strong, so that the occurrence of coma aberration becomes noticeable, making it difficult to correct the third lens unit become.

When the conditional expression (6) satisfies the range shown below, more preferable effects can be expected.
(6a) 0.3 ≦ | f2 / f3 | ≦ 0.9
By satisfying the range defined by the conditional expression (6a), a zoom lens with higher optical performance can be realized.

In addition, when the conditional expression (6a) satisfies the following range, it is possible to realize a zoom lens having higher optical performance.
(6b) 0.4 ≦ | f2 / f3 | ≦ 0.8

  Still another object of the present invention is to provide a zoom lens capable of satisfactorily correcting various aberrations generated for light in the visible light range to near-infrared light range. Therefore, in order to achieve the above purpose, various conditions as shown below are set.

In the zoom lens according to the present invention, the first lens group preferably includes at least one positive lens and one negative lens. Then, assuming that the Abbe number for the d-line of the positive lens in the first lens group is dd1p, and the Abbe number for the d-line of the negative lens in the first lens group is dd1n, the following conditional expression It is preferable to be satisfied.
(7) d d 1 p ≦ 41.0
(8) d d1 n 5 50.0

  Conditional expression (7) defines the Abbe number for the d-line of the positive lens, which is included in the first lens group, in order to satisfactorily correct the chromatic aberration generated in the negative lens, which is included in the first lens group. Indicates the condition of Further, conditional expression (8) defines the Abbe number for the d-line of the negative lens contained in the first lens group, and at the same time it reduces the chromatic aberration generated in the first lens group, spherical aberration, The conditions for correcting the curvature of field well are also shown.

  By satisfying the conditional expressions (7) and (8), the chromatic aberration generated by the negative lens included in the first lens group can be corrected well, and also the spherical aberration and the field curvature can be corrected well to obtain high optical power. Performance can be obtained. In particular, aberrations generated for light in the visible light region to the near infrared region can be well corrected.

  If the upper limit value is exceeded in the conditional expression (7), axial chromatic aberration and lateral chromatic aberration with respect to light in the visible light region to near infrared region generated in the first lens group increase, and optical performance is significantly degraded.

When the conditional expression (7) satisfies the range shown below, more preferable effects can be expected.
(7a) d d 1 p ≦ 33.5
By satisfying the range defined by the conditional expression (7a), a zoom lens with higher optical performance can be realized.

Further, when the conditional expression (7a) satisfies the following range, it is possible to realize a zoom lens having higher optical performance.
(7b) d d 1 p ≦ 26.0

  Below the lower limit of conditional expression (8), axial chromatic aberration to light in the visible to near-infrared regions generated in the first lens group increases, and optical performance is significantly degraded.

When the conditional expression (8) satisfies the range shown below, more preferable effects can be expected.
(8a) d d1 n 5 55.0
By satisfying the range defined by the conditional expression (8a), a zoom lens with higher optical performance can be realized.

In addition, when the conditional expression (8a) satisfies the following range, a zoom lens having higher optical performance can be realized.
(8b) d d1 n 6 60.0

Furthermore, in the zoom lens according to the present invention, it is preferable to satisfy the following conditional expression when an average value of Abbe's numbers for the d-line of the positive lens included in the second lens group is dd2pa.
(9) d d 2 pa 6 68.0

  Conditional expression (9) defines the average value of the Abbe number for the d-line of the positive lens included in the second lens group, and the chromatic aberration for light in the visible light range to the near infrared range generated in the second lens group It shows the conditions for making a good correction.

  Below the lower limit value of conditional expression (9), it becomes difficult to correct chromatic aberration for light in the visible light region to near infrared region generated in the second lens group, and optical performance is significantly degraded.

When the conditional expression (9) satisfies the range shown below, more preferable effects can be expected.
(9a) d d 2 pa 7 72.0
By satisfying the range defined by the conditional expression (9a), a zoom lens with higher optical performance can be realized.

In addition, when the conditional expression (9a) satisfies the range shown below, it is possible to realize a zoom lens with higher optical performance.
(9b) d d 2 pa 7 76.0

  Furthermore, in the zoom lens according to the present invention, the first lens group may be configured by arranging the negative lens, the negative lens, and the positive lens sequentially from the object side. In this way, it is possible to disperse the aberration generated by the negative refractive power by arranging the two negative lenses, and it is possible to reduce the occurrence of spherical aberration and curvature of field. Further, the spherical aberration and the curvature of field generated by the two negative lenses can be corrected by the positive lenses disposed on the image side thereof. Therefore, it is possible to effectively correct the spherical aberration and the curvature of field generated in the first lens unit.

  Furthermore, in the zoom lens according to the present invention, it is preferable that the third lens unit be arranged in order from the object side, with the negative lens and the positive lens being continuous. By doing this, it is possible to correct curvature of field and coma aberration generated in the first and second lens groups with the third lens group. Specifically, it is possible to correct curvature of field generated in the first and second lens groups by the negative lens of the third lens group. In addition, it is possible to correct coma aberration generated in the first and second lens groups by the positive lens of the third lens group.

Furthermore, in the zoom lens according to the present invention, the negative lens on the most object side of the third lens group is concave on the object side in order to correct field curvature generated in the first and second lens groups with the third lens group. It is preferable to be disposed toward the Then, the radius of curvature of the object side surface of the negative lens disposed closest to the object side of the third lens group is R31, and the radius of curvature of the image side surface of the negative lens disposed closest to the object side of the third lens group is R32. It is more preferable to satisfy the following conditional expression.
(10)-1.5 <(R31 + R32) / (R31-R32) <0.3

  Conditional expression (10) defines the radius of curvature of the object side surface of the concave lens disposed closest to the object side of the third lens group and the radius of curvature of the image side surface. By satisfying the conditional expression (10), curvature of field generated in the first and second lens units can be corrected well by the third lens unit.

  Below the lower limit of conditional expression (10), correction of curvature of field by the concave lens becomes excessive, and good optical performance can not be obtained. On the other hand, if conditional expression (10) exceeds the upper limit, correction | amendment of a curvature of field by the said concave lens will be insufficient, and a favorable optical performance will not be obtained.

When the conditional expression (10) satisfies the range shown below, more preferable effects can be expected.
(10a)-1.2 <(R31 + R32) / (R31-R32) <0.2
By satisfying the range defined by the conditional expression (10a), a zoom lens with higher optical performance can be realized.

When the conditional expression (10a) satisfies the following range, a zoom lens having higher optical performance can be realized.
(10b) -0.8 <(R31 + R32) / (R31-R32) <0.1

Furthermore, in the zoom lens according to the present invention, the amount of movement of the second lens unit during zooming from the wide-angle end to the telephoto end is X2, the focal length of the first lens unit is f1, and the focal length of the second lens unit is f2. When it is set, it is preferable to satisfy the following conditional expressions.
(11) 4.5 ≦ | X2 | ² /(|f1|×f2)≦16.5

  The amount of movement X2 of the second lens group means the point on the optical axis of the second lens group when the second lens group moves from the wide-angle end to the telephoto end with respect to one point fixed within a finite distance on the optical axis. The amount of movement of

  Conditional expression (11) defines the relationship between the movement amount of the second lens unit at the time of zooming from the wide-angle end to the telephoto end, the focal length of the first lens unit, and the focal length of the second lens unit. is there. By satisfying the conditional expression (11), the amount of movement of the second lens group at the time of zooming from the wide-angle end to the telephoto end is appropriately set, and shortening the total length of the optical system while maintaining optical performance. Can be

  If the lower limit value in conditional expression (11) is exceeded, it is possible to reduce the amount of movement of the second lens unit during zooming, but it becomes difficult to suppress the aberration associated with zooming. On the other hand, when the upper limit value is exceeded in the conditional expression (11), the moving amount of the second lens unit at the time of zooming increases, and the entire length of the optical system is extended.

When the conditional expression (11) satisfies the following range, more preferable effects can be expected.
(11a) 6.8 ≦ | X2 | ² /(|f1|×f2)≦15.2
By satisfying the range defined by the conditional expression (11a), it is possible to realize a zoom lens having a smaller size and high optical performance.

Further, when the conditional expression (11a) satisfies the following range, it is possible to realize a zoom lens which is smaller and has high optical performance.
(11b) 7.5 ≦ | X2 | ² /(|f1|×f2)≦14.5

Furthermore, in the zoom lens according to the present invention, when the focal length of the second lens group is f2 and the combined focal length at the wide-angle end of all the lens groups disposed after the third lens group is fLw, the following conditions are satisfied: It is preferable to satisfy the formula.
(12) 0.3 ≦ f2 / fLw ≦ 1.1

  Conditional expression (12) defines the ratio of the focal length of the second lens group to the combined focal length at the wide-angle end of all the lens groups disposed after the third lens group. By satisfying conditional expression (12), it is possible to satisfactorily correct coma aberration generated in the second lens group at the wide angle end with the third lens group and subsequent lens groups.

  If the lower limit value in conditional expression (12) is exceeded, the refractive powers of the third and subsequent lens groups become weak, and it becomes difficult to satisfactorily correct coma aberration generated in the second lens group. On the other hand, if the upper limit value is exceeded in the conditional expression (12), the refractive power of the second lens unit becomes too weak, so shortening of the total length of the optical system becomes difficult.

When the conditional expression (12) satisfies the range shown below, more preferable effects can be expected.
(12a) 0.48 ≦ f2 / fLw ≦ 0.92
By satisfying the range defined by the conditional expression (12a), it is possible to realize a zoom lens with smaller size and high optical performance.

In addition, when the conditional expression (12a) satisfies the following range, it is possible to realize a further compact zoom lens with high optical performance.
(12b) 0.55 ≦ f2 / fLw ≦ 0.85

  As described above, according to the present invention, by using the above-described configuration, a compact zoom lens having high optical performance that can correct various aberrations over the entire zoom range is realized. can do. Furthermore, it is possible to realize a compact, large aperture, high magnification zoom lens. In addition, it is possible to realize a zoom lens capable of satisfactorily correcting various aberrations generated for light in the visible light range to near-infrared light range.

  Hereinafter, embodiments of the zoom lens according to the present invention will be described in detail with reference to the drawings. The present invention is not limited by the following examples.

FIG. 1 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to a first example. The zoom lens comprises, in order from the object side, a first lens group G ₁₁ having a negative refractive power, a second lens group G ₁₂ having a positive refractive power, a third lens group having a positive refractive power G ₁₃ and are arranged and configured. Between the third lens group G ₁₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group G ₁₁ includes, in order from the object side, a negative lens L _111, a negative lens L _112, a positive lens L _113, a negative lens L _114, is formed are disposed. The negative lens L ₁₁₂ and the positive lens L ₁₁₃ are cemented. An aspheric surface is formed on the side of the image forming surface IMG of the positive lens L ₁₁₃ .

Second lens group G ₁₂ configured in order from the object side, a positive lens L _121, and the aperture stop STP defines a predetermined diameter, a negative lens L _122, a positive lens L _123, is the arrangement. The both surfaces of the positive lens L _121, aspheric surface is formed. The negative lens _L122 and the positive lens _L123 are cemented.

The third lens group G ₁₃ includes, in order from the object side, a negative lens L _131, a positive lens L _132, a positive lens L _133, is formed are disposed. The object side surface of the negative lens L ₁₃₁ is concave. Aspheric surfaces are formed on both surfaces of the positive lens L ₁₃₃ .

The zoom lens, the first lens group G ₁₁ is moved so as to form a convex locus to the image formation plane IMG side along the optical axis, and performs zooming from the wide-angle end to the telephoto end. Also, it is moved toward the object side from the image plane IMG side along the second lens group G ₁₂ to the optical axis, so as to form a trajectory of loose convex to the object side along the third lens group G ₁₃ to the optical axis , And correct the position of the imaging surface IMG involved in the magnification change. In this case, aperture stop STP is moved together with the second lens group G _12. Moreover, by moving toward the object side along the first lens group G ₁₁ to the optical axis to perform focusing from infinity in-focus state to a closest distance object in-focus state.

  Hereinafter, various numerical data on the zoom lens according to Example 1 will be shown.

Focal length of the entire zoom lens system = 3.19 (wide-angle end)-19.44 (telephoto end)
F number (FNO) = 1.23 (wide-angle end) to 3.44 (telephoto end)
Half angle of view (ω) = 58.37 (wide-angle end) to 8.53 (telephoto end)
The focal length of the first lens group G ₁₁ (f1) = - 8.91
Focal length of the second lens group G ₁₂ (f2) = 13.42
Focal length of the third lens group G ₁₃ (f3) = 20.43
Magnification ratio = 6.10

(Lens data)
r ₁ = 157.592
d ₁ = 0.50 nd ₁ = 1.83 d d ₁ = 42.72
r ₂ = 9.500
d ₂ = 5.28
r ₃ = -56.402
d ₃ = 0.50 nd ₂ = 1.49 d d ₂ = 70.44
r ₄ = 19.091
d ₄ = 3.86 nd ₃ = 1.82 dd ₃ = 24.06
r ₅ = -48.424 (aspheric surface)
d ₅ = 1.02
r ₆ = -16.500
d ₆ = 0.50 nd ₄ = 1.52 dd ₄ = 64.20
r ₇ = 47.208
d ₇ = D (7) (variable)
r ₈ = 12.507 (aspheric surface)
d ₈ = 3.83 nd ₅ = 1.55 d d ₅ = 71. 68
r ₉ = −21.857 (aspheric surface)
d ₉ = 0.71
r ₁₀ = ((aperture stop)
d ₁₀ = 1.57
r ₁₁ = 31.697
d ₁₁ = 0.50 nd ₆ = 1.72 dd ₆ = 29.50
r ₁₂ = 9.003
d ₁₂ = 4.03 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₃ = -17.916
d ₁₃ = D (13) (variable)
r ₁₄ = -9.959
d ₁₄ = 0.50 nd ₈ = 1.58 d d ₈ = 40.89
r ₁₅ = 11.066
d ₁₅ = 0.68
r ₁₆ = 15.141
d ₁₆ = 1.83 nd ₉ = 1.88 d d ₉ = 40.81
r ₁₇ = -39.802
d ₁₇ = 0.50
r ₁₈ = 49. 128 (aspheric surface)
d ₁₈ = 2.92 nd ₁₀ = 1.50 d d ₁₀ = 81.56
r ₁₉ = −9.723 (aspheric surface)
d ₁₉ = D (19) (variable)
r ₂₀ = ∞
d ₂₀ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₁ = ∞
d ₂₁ = 4.00
r ₂₂ = ∞ (imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = −6.72458 × 10 ⁻⁵ , C = −2.40695 × 10 ⁻⁷ ,
D = 2.61052 × 10 ⁻⁹ , E = −3.95672 × 10 ⁻¹¹
(Eighth)
k = 0,
A = 0,
B = -9.69395 × 10 ^-5 , C = -9.51005 × 10 ^-7 ,
D = 4.02158 × 10 ⁻⁸ , E = −6.43542 × 10 ⁻¹⁰
(9th side)
k = 0,
A = 0,
B = 1.00663 × 10 ⁻⁴ , C = −1.18082 × 10 ⁻⁶ ,
D = 4.06019 × 10 ^-8 , E = -6.35633 × 10 ^-10
(18th face)
k = 0,
A = 0,
B = 5.35557 × 10 ⁻⁴ , C = 2.45046 × 10 ⁻⁵ ,
D = -1.67573 x 10 ^-7 , E = 2.92 909 x 10 ^-8
(The 19th)
k = 0,
A = 0,
B = 8.27909 × 10 ⁻⁴ , C = 5.14824 × 10 ⁻⁵ ,
D = −2.72286 × 10 ⁻⁶ , E = 1.39662 × 10 ⁻⁷

(Modified data)
Wide-angle end Telephoto end
D (7) 26.85 1.00
D (13) 2.35 31.40
D (19) 2.03 1.35

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 5.87
.beta.2T: magnification at the telephoto end of the second lens group G ₁₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₁₂

(Numeric values related to conditional expression (2))
β2W = -0.43

(Numeric values related to conditional expression (3))
β2T = -2.53

(Numeric values related to conditional expression (4))
βLT = 0.86
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₁₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.66

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.66

(Numeric values related to conditional expression (7))
d d 1 p = 24.06
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₁₁₃ ) included in the first lens group G ₁₁

(Numeric values related to conditional expression (8))
d d 1 n = 70. 44
d d 1 n: Abbe's number for the d-line of the negative lens (negative lens L ₁₁₂ ) contained in the first lens group G ₁₁

(Numeric values related to conditional expression (9))
d d 2 pa = 83.39
d d 2 pa: average value of Abbe number for d-line of positive lens included in the second lens group G ₁₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) =-0.05
R31: third curvature of the object side surface of the most negative lens disposed on the object side L ₁₃₁ of lens group G ₁₃ radius R32: an image of the negative lens L ₁₃₁ most is located on the object side of the third lens group G ₁₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 6.73
X2: amount of movement of the second lens group G ₁₂ during zooming from the wide-angle end to the telephoto end (= 28.38)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.66
fLw: combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{13 and} thereafter

  FIG. 2 is a diagram showing various aberrations of the zoom lens according to the first example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 3 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to Example 2. FIG. The zoom lens comprises, in order from the object side, a first lens group G ₂₁ having a negative refractive power, a second lens group G ₂₂ having a positive refractive power, a third lens group having a positive refractive power G ₂₃ and are arranged and configured. Between the third lens group G ₂₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group G ₂₁ includes, in order from the object side, a negative lens L _211, a negative lens L _212, a positive lens L _213, a negative lens L _214, is formed are disposed. The negative lens L ₂₁₂ and the positive lens L ₂₁₃ are cemented. An aspheric surface is formed on the imaging surface IMG side of the positive lens L ₂₁₃ .

Second lens group G ₂₂ configured in order from the object side, a positive lens L _221, and the aperture stop STP defines a predetermined diameter, a negative lens L _222, a positive lens L _223, is the arrangement. Aspheric surfaces are formed on both surfaces of the positive lens L ₂₂₁ . The negative lens L ₂₂₂ and the positive lens L ₂₂₃ are cemented.

The third lens group G ₂₃ includes, in order from the object side, a negative lens L _231, a positive lens L _232, a positive lens L _233, is formed are disposed. The object side surface of the negative lens L ₂₃₁ is concave. Aspheric surfaces are formed on both surfaces of the positive lens L ₂₃₃ .

The zoom lens, the first lens group G ₂₁ is moved so as to form a convex locus to the image formation plane IMG side along the optical axis, and performs zooming from the wide-angle end to the telephoto end. Further, the second lens group G ₂₂ is moved along the optical axis from the imaging surface IMG side to the object side, and the third lens group G ₂₃ forms a locus of a loose convex on the object side along the optical axis. , And correct the position of the imaging surface IMG involved in the magnification change. In this case, aperture stop STP is moved together with the second lens group G _22. Moreover, by moving toward the object side along the first lens group G ₂₁ to the optical axis to perform focusing from infinity in-focus state to a closest distance object in-focus state.

  Hereinafter, various numerical data on the zoom lens according to Example 2 will be shown.

Focal length of the entire zoom lens system = 3.19 (wide-angle end)-19.44 (telephoto end)
F number (FNO) = 1.23 (wide-angle end) to 3.47 (telephoto end)
Half angle of view (ω) = 63.46 (wide-angle end) to 9.03 (telephoto end)
Focal length of the first lens group G ₂₁ (f 1) = − 9.02
Focal length of second lens group G ₂₂ (f 2) = 13.71
Focal length of the third lens group G ₂₃ (f3) = 20.36
Magnification ratio = 6.10

(Lens data)
r ₁ = 579.202
d ₁ = 0.50 nd ₁ = 1.90 d d ₁ = 37. 37
r ₂ = 9.500
d ₂ = 4.56
r ₃ = -218.921
d ₃ = 0.50 nd ₂ = 1.64 d d ₂ = 55.45
r ₄ = 23.130
d ₄ = 4.30 nd ₃ = 1.82 dd ₃ = 24.06
r ₅ = -22. 947 (aspheric surface)
d ₅ = 0.79
r ₆ = -12.801
d ₆ = 0.50 nd ₄ = 1.52 dd ₄ = 52.15
r ₇ = 53.596
d ₇ = D (7) (variable)
r ₈ = 12.385 (aspheric surface)
d ₈ = 4.09 nd ₅ = 1.55 dd ₅ = 71.68
r ₉ = -20.051 (aspheric surface)
d ₉ = 0.71
r ₁₀ = ((aperture stop)
d ₁₀ = 1.57
r ₁₁ = 53.272
d ₁₁ = 0.60 nd ₆ = 1.67 d d ₆ = 32.17
r ₁₂ = 8.806
d ₁₂ = 4.08 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₃ = -17.193
d ₁₃ = D (13) (variable)
r ₁₄ = -8.512
d ₁₄ = 0.50 nd ₈ = 1.52 d d ₈ = 52.15
r ₁₅ = -211.125
d ₁₅ = 0.57
r ₁₆ = -19.080
d ₁₆ = 1.67 nd ₉ = 1.50 d d ₉ = 81.61
r ₁₇ = -9.123
d ₁₇ = 0.50
r ₁₈ = 30.680 (aspheric surface)
d ₁₈ = 2.59 nd ₁₀ = 1.50 dd ₁₀ = 81.56
r ₁₉ = −10.864 (aspheric surface)
d ₁₉ = D (19) (variable)
r ₂₀ = ∞
d ₂₀ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₁ = ∞
d ₂₁ = 4.00
r ₂₂ = ∞ (imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = -9.10507 × 10 ^-5 , C = -5.33991 × 10 ^-7 ,
D = 2.86663 × 10 ⁻⁹ , E = −7.37298 × 10 ⁻¹¹
(Eighth)
k = 0,
A = 0,
B = -9.81882 × 10 ^-5 , C = -6.15235 × 10 ^-7 ,
D = 2.80365 × 10 ⁻⁸ , E = −4.53885 × 10 ⁻¹⁰
(9th side)
k = 0,
A = 0,
B = 1.12174 × 10 ⁻⁴ , C = −8.11729 × 10 ⁻⁷ ,
D = 2.63785 × 10 ⁻⁸ , E = −4.1989 5 × 10 ⁻¹⁰
(18th face)
k = 0,
A = 0,
B = 2.38585 × 10 ⁻⁴ , C = 2.31778 × 10 ⁻⁵ ,
D = -3.13210 × 10 ^-7 , E = 3.70085 × 10 ^-8
(The 19th)
k = 0,
A = 0,
B = 5.36748 × 10 ⁻⁴ , C = 4.77277 × 10 ⁻⁵ ,
D = -2.53469 x 10 ^-6 , E = 1.21543 x 10 ^-7

(Modified data)
Wide-angle end Telephoto end
D (7) 27.49 1.00
D (13) 2.40 32.02
D (19) 2.03 1.43

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 5.88
.beta.2T: magnification at the telephoto end of the second lens group G ₂₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₂₂

(Numeric values related to conditional expression (2))
β2W = -0.43

(Numeric values related to conditional expression (3))
β2T = -2.53

(Numeric values related to conditional expression (4))
βLT = 0.85
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₂₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.66

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.67

(Numeric values related to conditional expression (7))
d d 1 p = 24.06
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₂₁₃ ) contained in the first lens group G ₂₁

(Numeric values related to conditional expression (8))
d d1 n = 52.15
d d 1 n: Abbe's number for the d-line of the negative lens (negative lens L ₂₁₄ ) contained in the first lens group G ₂₁

(Numeric values related to conditional expression (9))
d d 2 pa = 83.39
d d 2 pa: average value of Abbe number for d-line of positive lens included in the second lens group G ₂₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) =-1.08
R31: third curvature of the object side surface of the lens group G negative lens L ₂₃₁ most is located on the object side of the ₂₃ radius R32: an image of the negative lens L ₂₃₁ most is located on the object side of the third lens group G ₂₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 6.82
X2: Movement amount of the second lens group G ₂₂ during zooming from the wide-angle end to the telephoto end (= 29.03)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.67
fLw: combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{23 and} thereafter

  FIG. 4 is a diagram of various aberrations of the zoom lens according to the second example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 5 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to Example 3. FIG. The zoom lens comprises, in order from the object side, a first lens group G ₃₁ having a negative refractive power, a second lens group G ₃₂ having a positive refractive power, a third lens group having a positive refractive power G ₃₃ and are arranged and configured. Between the third lens group G ₃₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group G ₃₁ includes, in order from the object side, a negative lens L _311, a negative lens L _312, a positive lens L _313, a negative lens L _314, is formed are disposed. An aspheric surface is formed on the object side surface of the positive lens L ₃₁₃ . In addition, an aspheric surface is also formed on the side of the imaging surface IMG of the negative lens L ₃₁₄ .

The second lens group G ₃₂ is constituted in order from the object side, a positive lens L _321, and the aperture stop STP defines a predetermined diameter, a negative lens L _322, a positive lens L _323, is the arrangement. Aspheric surfaces are formed on both surfaces of the positive lens L ₃₂₁ . The negative lens L ₃₂₂ and the positive lens L ₃₂₃ are cemented.

The third lens group _G33 includes, in order from the object side, a negative lens _L331 , a positive lens _L332, and a positive lens _L333 . The object side surface of the negative lens L ₃₃₁ is concave. Aspheric surfaces are formed on both surfaces of the positive lens _L333 .

This zoom lens moves the first lens group G ₃₁ along the optical axis so as to form a convex locus on the imaging surface IMG side, and performs zooming from the wide-angle end to the telephoto end. Further, the second lens group G ₃₂ is moved along the optical axis from the imaging surface IMG side to the object side, and the third lens group G ₃₃ is moved along the optical axis from the object side to the imaging surface IMG side Correction of the position of the imaging surface IMG accompanying the magnification change. In this case, aperture stop STP is moved together with the second lens group G _32. Moreover, by moving toward the object side along the first lens group G ₃₁ to the optical axis to perform focusing from infinity in-focus state to a closest distance object in-focus state.

  Hereinafter, various numerical data on the zoom lens according to Example 3 will be shown.

Focal length of the whole zoom lens system = 3.09 (wide-angle end)-24.31 (telephoto end)
F-number (FNO) = 1.23 (wide-angle end) to 5.41 (telephoto end)
Half angle of view (ω) = 53.02 (wide-angle end) to 6.77 (telephoto end)
Focal length of first lens group G ₃₁ (f 1) = − 8.72
Focal length of the second lens group G ₃₂ (f 2) = 13.62
Focal length (f3) of third lens group G ₃₃ = 20.13
Magnification ratio = 7.88

(Lens data)
r ₁ = 95.832
d ₁ = 0.50 nd ₁ = 1.88 d d ₁ = 40.81
r ₂ = 9.500
d ₂ = 3.14
r ₃ = 19.545
d ₃ = 0.50 nd ₂ = 1.74 dd ₂ = 49.22
r ₄ = 10.200
d ₄ = 1.77
r ₅ = 28.685 (aspheric surface)
d ₅ = 4.02 nd ₃ = 1.82 dd ₃ = 24.06
r ₆ = -22.559
d ₆ = 0.57
r ₇ = -16.524
d ₇ = 0.50 nd ₄ = 1.62 dd ₄ = 63.86
r ₈ = 39.439 (aspheric surface)
d ₈ = D (8) (variable)
r ₉ = 10.268 (aspheric surface)
d ₉ = 4.68 nd ₅ = 1.50 d d ₅ = 81.56
r ₁₀ = −22.386 (aspheric surface)
d ₁₀ = 0.71
r ₁₁ = ((aperture stop)
d ₁₁ = 1.57
r ₁₂ = 14.513
d ₁₂ = 0.60 nd ₆ = 1.90 dd ₆ = 31.01
r ₁₃ = 7.283
d ₁₃ = 4.62 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₄ = -37.400
d ₁₄ = D (14) (variable)
r ₁₅ = -11.084
d ₁₅ = 0.50 nd ₈ = 1.70 dd ₈ = 41.15
r ₁₆ = 10.957
d ₁₆ = 0.66
r ₁₇ = 16.980
d ₁₇ = 1.84 nd ₉ = 1.88 d d ₉ = 40.81
r ₁₈ = −21.649
d ₁₈ = 0.50
r ₁₉ = 53.019 (aspheric surface)
d ₁₉ = 2.56 nd ₁₀ = 1.50 d d ₁₀ = 81.56
r ₂₀ = −9.689 (aspheric surface)
d ₂₀ = D (20) (variable)
r ₂₁ = ∞
d ₂₁ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₂ = ∞
d ₂₂ = 4.00
r ₂₃ = ((imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = 1.40806 × 10 ⁻⁵ , C = 3.25534 × 10 ⁻⁶ ,
D = -4.17170 x 10 ^-8 , E = 6.04485 x 10 ^-10
(Eighth)
k = 0,
A = 0,
B = -1. 81784 × 10 ^-4 , C = 1.95668 × 10 ^-6 ,
D = -1. 622257 × 10 ^-8 , E = 5.45870 × 10 ^-11
(9th side)
k = 0,
A = 0,
B = -1.20860 × 10 ⁻⁴ , C = −1.52404 × 10 ⁻⁶ ,
D = 3.61163 x 10 ^-8 , E = -5.3905 x 10 ^-10
(Ten 10)
k = 0,
A = 0,
B = 1.0 0026 × 10 ⁻⁴ , C = −1.20395 × 10 ⁻⁶ ,
D = 2.99744 × 10 ⁻⁸ , E = −3.95433 × 10 ⁻¹⁰
(The 19th)
k = 0,
A = 0,
B = 4.25522 × 10 ⁻⁴ , C = 2.39298 × 10 ⁻⁵ ,
D = 3.22213 × 10 ⁻⁷ , E = 3.18531 × 10 ⁻⁸
(The 20th)
k = 0,
A = 0,
B = 6.35974 × 10 ^-4 , C = 6.79239 × 10 ^-5 ,
D = -3.88398 x 10 ^-6 , E = 1.94713 x 10 ^-7

(Modified data)
Wide-angle end Telephoto end
D (8) 30.55 1.12
D (14) 2.17 38.62
D (20) 1.50 0.51

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 7.46
.beta.2T: magnification at the telephoto end of the second lens group G ₃₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₃₂

(Numeric values related to conditional expression (2))
β2W = -0.40

(Numeric values related to conditional expression (3))
β2T = -2.99

(Numeric values related to conditional expression (4))
βLT = 0.93
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₃₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.64

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.68

(Numeric values related to conditional expression (7))
d d 1 p = 24.06
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₃₁₃ ) contained in the first lens group G ₃₁

(Numeric values related to conditional expression (8))
d d 1 n = 63. 86
d d 1 n: Abbe's number for the d-line of the negative lens (negative lens L ₃₁₄ ) contained in the first lens group G ₃₁

(Numeric values related to conditional expression (9))
d d 2 pa = 88.33
d d 2 pa: Average value of Abbe number for d-line of positive lens included in the second lens group G ₃₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) = 0.04
R31: third curvature of the object side surface of the most negative lens disposed on the object side L ₃₃₁ of lens group G ₃₃ radius R32: an image of the negative lens L ₃₃₁ most is located on the object side of the third lens group G ₃₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 10.59
X2: Movement amount of the second lens group G ₃₂ during zooming from the wide-angle end to the telephoto end (= 39.46)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.72
fLw: combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{33 and} thereafter

  FIG. 6 is a diagram of various aberrations of the zoom lens according to the third example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 7 is a cross-sectional view along the optical axis showing the configuration of the zoom lens according to Example 4. This zoom lens includes, in order from an object side not shown, a first lens group G ₄₁ having negative refractive power, a second lens group G ₄₂ having positive refractive power, and a third lens group having positive refractive power. G ₄₃ and are arranged and configured. Between the third lens group G ₄₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group _G41 includes, in order from the object side, a negative lens _L411 , a negative lens _L412 , a positive lens _L413, and a negative lens _L414 . An aspheric surface is formed on the object side surface of the positive lens L ₄₁₃ . In addition, an aspheric surface is also formed on the side of the imaging surface IMG of the negative lens L ₄₁₄ .

The second lens group G ₄₂ is constituted in order from the object side, a positive lens L _421, and the aperture stop STP defines a predetermined diameter, a negative lens L _422, a positive lens L _423, is the arrangement. Aspheric surfaces are formed on both surfaces of the positive lens L ₄₂₁ . The negative lens L ₄₂₂ and the positive lens L ₄₂₃ are cemented.

The third lens group _G43 includes, in order from the object side, a negative lens _L431 , a positive lens _L432, and a positive lens _L433 . The object side surface of the negative lens L ₄₃₁ is concave. Aspheric surfaces are formed on both surfaces of the positive lens L ₄₃₃ .

This zoom lens moves the first lens group G ₄₁ along the optical axis so as to form a convex locus on the imaging surface IMG side, and performs magnification change from the wide-angle end to the telephoto end. Further, the second lens group G ₄₂ is moved along the optical axis from the imaging surface IMG side to the object side, and the third lens group G ₄₃ is moved along the optical axis from the object side to the imaging surface IMG side Correction of the position of the imaging surface IMG accompanying the magnification change. In this case, aperture stop STP is moved together with the second lens group G _42. Further, by moving the first lens group G ₄₁ toward the object side along the optical axis, focusing from an infinite distance object focusing state to a closest distance distance object focusing state is performed.

  Hereinafter, various numerical data on the zoom lens according to Example 4 will be shown.

Focal length of the entire zoom lens system = 3.09 (wide-angle end) to 25.28 (telephoto end)
F number (FNO) = 1.24 (wide-angle end) to 5.59 (telephoto end)
Half angle of view (ω) = 51.14 (wide-angle end) to 6.52 (telephoto end)
Focal length of the first lens group G ₄₁ (f 1) = − 8.88
Focal length of the second lens group G ₄₂ (f 2) = 13.73
Focal length (f3) of third lens group G ₄₃ = 19.12
Magnification ratio = 8.19

(Lens data)
r ₁ = 46.713
d ₁ = 0.50 nd ₁ = 1.88 d d ₁ = 40.81
r ₂ = 9.500
d ₂ = 3.66
r ₃ = 21.676
d ₃ = 0.50 nd ₂ = 1.74 dd ₂ = 49.22
r ₄ = 10.262
d ₄ = 1.91
r ₅ = 27.990 (aspheric surface)
d ₅ = 4.13 nd ₃ = 1.82 d d ₃ = 24.06
r ₆ = −23.453
d ₆ = 0.61
r ₇ = -16.902
d ₇ = 0.50 nd ₄ = 1.62 dd ₄ = 63.86
r ₈ = 34.085 (aspheric surface)
d ₈ = D (8) (variable)
r ₉ = 10.227 (aspheric surface)
d ₉ = 4.75 nd ₅ = 1.50 d d ₅ = 81.56
r ₁₀ = -22.296 (aspheric surface)
d ₁₀ = 0.71
r ₁₁ = ((aperture stop)
d ₁₁ = 1.57
r ₁₂ = 14.438
d ₁₂ = 0.60 nd ₆ = 1.90 dd ₆ = 31.01
r ₁₃ = 7.228
d ₁₃ = 4.59 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₄ = -43.169
d ₁₄ = D (14) (variable)
r ₁₅ = -11.021
d ₁₅ = 0.50 nd ₈ = 1.70 dd ₈ = 41.15
r ₁₆ = 10.104
d ₁₆ = 0.72
r ₁₇ = 16.174
d ₁₇ = 1.87 nd ₉ = 1.88 8 d ₉ = 40.81
r ₁₈ = −21.359
d ₁₈ = 0.50
r ₁₉ = 52. 774 (aspheric surface)
d ₁₉ = 2.62 nd ₁₀ = 1.50 dd ₁₀ = 81.56
r ₂₀ = -9.309 (aspheric surface)
d ₂₀ = D (20) (variable)
r ₂₁ = ∞
d ₂₁ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₂ = ∞
d ₂₂ = 4.00
r ₂₃ = ((imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = -4.22 974 x 10 ^-6 , C = 3.00580 x 10 ^-6 ,
D = −3.72775 × 10 ⁻⁸ , E = 5.19830 × 10 ⁻¹⁰
(Eighth)
k = 0,
A = 0,
B = -1.96237 × 10 ^-4 , C = 1.99541 × 10 ^-6 ,
D = -1.40593 x 10 ^-8 , E = 3.63024 x 10 ^-11
(9th side)
k = 0,
A = 0,
B = -1. 22444 × 10 ^-4 , C = -1.45093 × 10 ^-6 ,
D = 3.34444 × 10 ⁻⁸ , E = −5.05995 × 10 ⁻¹⁰
(Ten 10)
k = 0,
A = 0,
B = 9.71687 × 10 ⁻⁵ , C = −1.08483 × 10 ⁻⁶ ,
D = 2.66175 × 10 ⁻⁸ , E = −3.52297 × 10 ⁻¹⁰
(The 19th)
k = 0,
A = 0,
B = 3.62043 × 10 ⁻⁴ , C = 2.31518 × 10 ⁻⁵ ,
D = 2.37504 x 10 ^-7 , E = 3.55302 x 10 ^-8
(The 20th)
k = 0,
A = 0,
B = 5.38706 × 10 ⁻⁴ , C = 6.98508 × 10 ⁻⁵ ,
D = −4.18158 × 10 ⁻⁶ , E = 1.96092 × 10 ⁻⁷

(Modified data)
Wide-angle end Telephoto end
D (8) 31.53 1.13
D (14) 2.20 39.68
D (20) 1.50 0.45

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 7.71
.beta.2T: magnification at the telephoto end of the second lens group G ₄₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₄₂

(Numeric values related to conditional expression (2))
β 2 W = −0.39

(Numeric values related to conditional expression (3))
β2T = -3.03

(Numeric values related to conditional expression (4))
βLT = 0.94
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₄₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.65

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.72

(Numeric values related to conditional expression (7))
d d 1 p = 24.06
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₄₁₃ ) included in the first lens group G ₄₁

(Numeric values related to conditional expression (8))
d d 1 n = 63. 86
d d1 n: Abbe's number for the d-line of the negative lens (negative lens L ₄₁₄ ) contained in the first lens group G ₄₁

(Numeric values related to conditional expression (9))
d d 2 pa = 88.33
d d 2 pa: average value of Abbe number for d-line of positive lens included in second lens group G ₄₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) = 0.04
R31: third curvature of the object side surface of the negative lens L ₄₃₁ most is located on the object side of the lens group G ₄₃ radius R32: an image of the negative lens L _431, which is disposed on the most object side of the third lens group G ₄₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 10.88
X2: Movement amount of second lens group G ₄₂ during zooming from the wide angle end to the telephoto end (= 36.43)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.72
fLw: combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{43 and} thereafter

  FIG. 8 is a diagram of various aberrations of the zoom lens according to the fourth example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 9 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to a fifth example. This zoom lens comprises, in order from the object side not shown, a first lens group G ₅₁ having negative refractive power, a second lens group G ₅₂ having positive refractive power, and a third lens group having positive refractive power. G ₅₃ and are arranged and configured. Between the third lens group G ₅₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group _G51 includes, in order from the object side, a negative lens _L511 , a negative lens _L512 , a positive lens _L513, and a negative lens _L514 . An aspheric surface is formed on the object side surface of the positive lens L ₅₁₃ . In addition, an aspheric surface is also formed on the side of the imaging surface IMG of the negative lens L ₅₁₄ .

The second lens group G ₅₂ is constituted in order from the object side, a positive lens L _521, and the aperture stop STP defines a predetermined diameter, a negative lens L _522, a positive lens L _523, is the arrangement. Aspheric surfaces are formed on both surfaces of the positive lens L ₅₂₁ . The negative lens L ₅₂₂ and the positive lens L ₅₂₃ are cemented.

The third lens group G ₅₃ is configured by arranging a negative lens L ₅₃₁ , a positive lens L _532, and a positive lens L _{533 in} order from the object side. The object side surface of the negative lens L ₅₃₁ is concave. Aspheric surfaces are formed on both sides of the positive lens L ₅₃₃ .

This zoom lens moves the first lens group G ₅₁ along the optical axis so as to form a convex locus on the imaging surface IMG side, and performs magnification change from the wide-angle end to the telephoto end. In addition, the second lens group G ₅₂ is moved from the imaging surface IMG side to the object side along the optical axis, and the third lens group G ₅₃ forms a loose convex locus on the object side along the optical axis. , And correct the position of the imaging surface IMG involved in the magnification change. In this case, aperture stop STP is moved together with the second lens group G _52. Further, by moving the first lens group G ₅₁ to the object side along the optical axis, focusing from an infinite distance object focusing state to a closest distance distance object focusing state is performed.

  Hereinafter, various numerical data on the zoom lens according to Example 5 will be shown.

Focal length of the whole zoom lens system = 3.09 (wide-angle end) to 31.14 (telephoto end)
F-number (FNO) = 1.23 (wide-angle end) to 6.50 (telephoto end)
Half angle of view (ω) = 55.16 (wide-angle end) to 5.71 (telephoto end)
Focal length of the first lens group G ₅₁ (f 1) = − 9.90
Focal length of the second lens group G ₅₂ (f 2) = 14.96
Focal length (f3) of third lens group G ₅₃ = 19.46
Magnification ratio = 10.09

(Lens data)
r ₁ = 26.825
d ₁ = 0.50 nd ₁ = 1.88 d d ₁ = 40.81
r ₂ = 9.500
d ₂ = 6.87
r ₃ = 283.853
d ₃ = 0.50 nd ₂ = 1.64 d d ₂ = 55.45
r ₄ = 13.341
d ₄ = 1.24
r ₅ = 18.652 (aspheric surface)
d ₅ = 5.37 nd ₃ = 1.90 d d ₃ = 31.01
r ₆ = -20.586
d ₆ = 0.32
r ₇ = -18.586
d ₇ = 0.50 nd ₄ = 1.62 dd ₄ = 63.86
r ₈ = 14.772 (aspheric surface)
d ₈ = D (8) (variable)
r ₉ = 10.932 (aspheric surface)
d ₉ = 4.89 nd ₅ = 1.50 dd ₅ = 81.56
r ₁₀ = −22.740 (aspheric surface)
d ₁₀ = 0.71
r ₁₁ = ((aperture stop)
d ₁₁ = 1.57
r ₁₂ = 15.124
d ₁₂ = 0.60 nd ₆ = 1.80 dd ₆ = 29.84
r ₁₃ = 7.157
d ₁₃ = 4.47 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₄ = 415. 217
d ₁₄ = D (14) (variable)
r ₁₅ = -9.835
d ₁₅ = 0.50 nd ₈ = 1.62 d d ₈ = 36.30
r ₁₆ = 11.290
d ₁₆ = 0.47
r ₁₇ = 14.063
d ₁₇ = 1.75 nd ₉ = 1.85 d d ₉ = 32. 27
r ₁₈ = −48.539
d ₁₈ = 0.50
r ₁₉ = 51.226 (aspheric surface)
d ₁₉ = 2.76 nd ₁₀ = 1.50 dd ₁₀ = 81.56
r ₂₀ = −7.918 (aspheric surface)
d ₂₀ = D (20) (variable)
r ₂₁ = ∞
d ₂₁ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₂ = ∞
d ₂₂ = 4.00
r ₂₃ = ((imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = -1.08363 x 10 ^-4 , C = 1.59004 x 10 ^-6 ,
D = -1.70725 × 10 ⁻⁸ , E = 1.67325 × 10 ⁻¹⁰
(Eighth)
k = 0,
A = 0,
B = -3.13596 x 10 ^-4 , C = 2.52792 x 10 ^-6 ,
D = -3. 21565 x 10 ^-8 , E = 2. 34769 x 10 ^-10
(9th side)
k = 0,
A = 0,
B = -1.02452 x 10 ^-4 , C = -5.67217 x 10 ^-7 ,
D = 6.25623 × 10 ⁻⁹ , E = −1.12478 × 10 ⁻¹⁰
(Ten 10)
k = 0,
A = 0,
B = 6.94091 × 10 ⁻⁵ , C = −4.62562 × 10 ⁻⁷ ,
D = 9.12845 x 10 ^-9 , E = -8.83652 x 10 ^-11
(The 19th)
k = 0,
A = 0,
B = 3.19106 × 10 ^-4 , C = 1.97993 × 10 ^-5 ,
D = 1.84618 × 10 ⁻⁷ , E = 3.07653 × 10 ⁻⁸
(The 20th)
k = 0,
A = 0,
B = 7.27355 × 10 ^-4 , C = 5.37611 × 10 ^-5 ,
D = −3.02061 × 10 ⁻⁶ , E = 1.47278 × 10 ⁻⁷

(Modified data)
Wide-angle end Telephoto end
D (8) 37.74 1.49
D (14) 2.54 50.18
D (20) 1.65 0.29

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 9.33
.beta.2T: magnification at the telephoto end of the second lens group G ₅₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₅₂

(Numeric values related to conditional expression (2))
β2W = -0.37

(Numeric values related to conditional expression (3))
β2T = -3.44

(Numeric values related to conditional expression (4))
βLT = 0.92
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₅₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.66

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.77

(Numeric values related to conditional expression (7))
d d 1 p = 31.01
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₅₁₃ ) contained in the first lens group G ₅₁

(Numeric values related to conditional expression (8))
d d 1 n = 63. 86
d d 1 n: Abbe's number for the d-line of the negative lens (negative lens L ₅₁₄ ) contained in the first lens group G ₅₁

(Numeric values related to conditional expression (9))
d d 2 pa = 88.33
d d 2 pa: Average value of Abbe number for d-line of positive lens included in the second lens group G ₅₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) = -0.07
R31: third curvature of the object side surface of the most negative lens disposed on the object side L ₅₃₁ of lens group G ₅₃ radius R32: an image of the negative lens L ₅₃₁ most is located on the object side of the third lens group G ₅₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 14.46
X2: Movement amount of second lens group G ₅₂ during zooming from the wide-angle end to the telephoto end (= 46.27)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.77
fLw: Combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{53 and} after

  FIG. 10 is a diagram showing various aberrations of the zoom lens according to the fifth example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 11 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to a sixth example. The zoom lens comprises, in order from the object side, a first lens group G ₆₁ having a negative refractive power, a second lens group G ₆₂ having a positive refractive power, a third lens group having a positive refractive power G ₆₃ and are arranged and configured. Between the third lens group G ₆₃ and the image plane IMG, a cover glass CG is disposed.

The first lens group G ₆₁ includes, in order from the object side, a negative lens L _611, a negative lens L _612, a positive lens L _613, a negative lens L _614, is formed are disposed. The negative lens L ₆₁₂ and the positive lens L ₆₁₃ are cemented. An aspheric surface is formed on the imaging surface IMG side of the positive lens L ₆₁₃ .

The second lens group G ₆₂ is configured by arranging, in order from the object side, an aperture stop STP that defines a predetermined aperture, a positive lens L ₆₂₁ , a negative lens L _622, and a positive lens L ₆₂₃ . Aspheric surfaces are formed on both surfaces of the positive lens L ₆₂₁ . The negative lens L ₆₂₂ and the positive lens L ₆₂₃ are cemented.

The third lens group G ₆₃ includes, in order from the object side, a negative lens L _631, a positive lens L _632, a positive lens L _633, is formed are disposed. The object side surface of the negative lens L ₆₃₁ is concave. Aspheric surfaces are formed on both surfaces of the positive lens L ₆₃₃ .

This zoom lens moves the first lens group G ₆₁ along the optical axis so as to form a convex locus on the imaging surface IMG side, and performs magnification change from the wide-angle end to the telephoto end. Also, move the second lens group G ₆₂ from the imaging surface IMG side to the object side along the optical axis, and move the third lens group G ₆₃ from the object side to the imaging surface IMG side along the optical axis Correction of the position of the imaging surface IMG accompanying the magnification change. In this case, aperture stop STP is moved together with the second lens group G _62. Further, by moving the first lens group G ₆₁ to the object side along the optical axis, focusing from an infinite distance object focusing state to a closest distance distance object focusing state is performed.

  Hereinafter, various numerical data on the zoom lens according to Example 6 will be shown.

Focal length of the entire zoom lens system = 3.19 (wide-angle end)-19.44 (telephoto end)
F number (FNO) = 1.23 (wide-angle end) to 3.46 (telephoto end)
Half angle of view (ω) = 63.45 (wide-angle end) to 9.03 (telephoto end)
Focal length of the first lens group G ₆₁ (f 1) = − 8.87
Focal length of the second lens group G ₆₂ (f 2) = 14.15
Focal length (f3) of third lens group G ₆₃ = 20.70
Magnification ratio = 6.09

(Lens data)
r ₁ = -1214.004
d ₁ = 0.50 nd ₁ = 1.90 d d ₁ = 37. 37
r ₂ = 9.500
d ₂ = 4.39
r ₃ = −41.362
d ₃ = 0.50 nd ₂ = 1.62 dd ₂ = 60.34
r ₄ = 34.311
d ₄ = 3.06 nd ₃ = 1.92 dd ₃ = 20.88
r ₅ = -38.697 (aspheric surface)
d ₅ = 0.82
r ₆ = -16.500
d ₆ = 0.50 nd ₄ = 1.50 d d ₄ = 81.56
r ₇ = -276.937
d ₇ = D (7) (variable)
r ₈ = ((aperture stop)
d ₈ = 0.10
r ₉ = 11.908 (aspheric surface)
d ₉ = 4.09 nd ₅ = 1.55 d d ₅ = 71. 68
r ₁₀ = −23.716 (aspheric surface)
d ₁₀ = 2.28
r ₁₁ = 31.163
d ₁₁ = 0.60 nd ₆ = 1.74 d d ₆ = 32.26
r ₁₂ = 8.502
d ₁₂ = 4.13 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₃ = -20.456
d ₁₃ = D (13) (variable)
r ₁₄ = -8.639
d ₁₄ = 0.50 nd ₈ = 1.52 d d ₈ = 52.15
r ₁₅ = 49.450
d ₁₅ = 0.53
r ₁₆ = -56.822
d ₁₆ = 1.83 nd ₉ = 1.55 d d ₉ = 71.68
r ₁₇ = -10.549
d ₁₇ = 0.50
r ₁₈ == 37.725 (aspheric surface)
d ₁₈ = 2.56 nd ₁₀ = 1.50 d d ₁₀ = 81.56
r ₁₉ = −10.893 (aspheric surface)
d ₁₉ = D (19) (variable)
r ₂₀ = ∞
d ₂₀ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₁ = ∞
d ₂₁ = 4.00
r ₂₂ = ∞ (imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = −6.43049 × 10 ⁻⁵ , C = −3.13937 × 10 ⁻⁷ ,
D = 7.90770 × 10 ⁻¹⁰ , E = −2.56196 × 10 ⁻¹¹
(9th side)
k = 0,
A = 0,
B = -9.58017 x 10 ^-5 , C = -5.28701 x 10 ^-7 ,
D = 2.20174 × 10 ⁻⁸ , E = −3.25046 × 10 ⁻¹⁰
(Ten 10)
k = 0,
A = 0,
B = 9.23714 x 10 ^-5 , C = -7.68271 x 10 ^-7 ,
D = 2.53988 x 10 ^-8 , E = -3.43261 x 10 ^-10
(18th face)
k = 0,
A = 0,
B = 2.09121 x 10 ^-4 , C = 1.63339 x 10 ^-5 ,
D = 1.84981 x 10 ^-8 , E = 2.83988 x 10 ^-8
(The 19th)
k = 0,
A = 0,
B = 4.45201 × 10 ⁻⁴ , C = 3.75015 × 10 ⁻⁵ ,
D = -1.86997 × 10 ^-6 , E = 9.73204 × 10 ^-8

(Modified data)
Wide-angle end Telephoto end
D (7) 28.19 1.95
D (13) 2.30 33.89
D (19) 2.58 1.76

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 5.82
.beta.2T: magnification at the telephoto end of the second lens group G ₆₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₆₂

(Numeric values related to conditional expression (2))
β 2 W = -0.45

(Numeric values related to conditional expression (3))
β2T = -2.60

(Numeric values related to conditional expression (4))
βLT = 0.84
βLT: Magnification at the telephoto end of the lens unit (third lens unit G ₆₃ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.63

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.68

(Numeric values related to conditional expression (7))
d d 1 p = 20.88
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₆₁₃ ) included in the first lens group G ₆₁

(Numeric values related to conditional expression (8))
d d1 n = 81.56
d d 1 n: Abbe's number for the d-line of the negative lens (negative lens L ₆₁₄ ) contained in the first lens group G ₆₁

(Numeric values related to conditional expression (9))
d d 2 pa = 83.39
d d 2 pa: average value of Abbe number for d-line of positive lens included in the second lens group G ₆₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) = -0.70
R31: third curvature of the object side surface of the negative lens L ₆₃₁ most is located on the object side of the lens group G ₆₃ radius R32: an image of the negative lens L _631, which is disposed on the most object side of the third lens group G ₆₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 7.55
X2: Movement amount of second lens group G ₆₂ during zooming from the wide-angle end to the telephoto end (= 30.78)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.68
fLw: combined focal length at the wide-angle end of all lens units arranged in the third lens unit G _{63 and} thereafter

  FIG. 12 is a diagram of various aberrations of the zoom lens according to the sixth example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

FIG. 13 is a cross-sectional view along an optical axis showing a configuration of a zoom lens according to a seventh example. This zoom lens includes, in order from an object side not shown, a first lens group G ₇₁ having negative refractive power, a second lens group G ₇₂ having positive refractive power, and a third lens group having negative refractive power. and G _73, and the fourth lens group G ₇₄ having a positive refractive power, is configured are arranged. In addition, a cover glass CG is disposed between the fourth lens group _G74 and the imaging surface IMG.

The first lens group G ₇₁ includes, in order from the object side, a negative lens L _711, a negative lens L _712, a positive lens L _713, a negative lens L _714, is formed are disposed. An aspheric surface is formed on the object side surface of the positive lens L ₇₁₃ . In addition, an aspheric surface is also formed on the side of the image forming surface IMG of the negative lens L ₇₁₄ .

The second lens group _G72 includes, in order from the object side, a positive lens _L721 , an aperture stop STP defining a predetermined aperture, a negative lens _L722, and a positive lens _L723 . Aspheric surfaces are formed on both surfaces of the positive lens L ₇₂₁ . The negative lens L ₇₂₂ and the positive lens L ₇₂₃ are cemented.

The third lens group G ₇₃ includes, in order from the object side, a negative lens L _731, a positive lens L _732, is formed are disposed. The object side surface of the negative lens L ₇₃₁ is concave.

The fourth lens group G ₇₄ is composed of a positive lens L ₇₄₁ . Aspheric surfaces are formed on both surfaces of the positive lens L ₇₄₁ .

This zoom lens moves the first lens group G ₇₁ along the optical axis so as to form a convex locus on the imaging surface IMG side, and performs magnification change from the wide-angle end to the telephoto end. In addition, while moving the second lens group G ₇₂ from the imaging surface IMG side to the object side along the optical axis, the third lens group G ₇₃ has a loose convex locus along the optical axis to the imaging surface IMG side. Then, the fourth lens group G ₇₄ is moved from the object side to the imaging surface IMG side along the optical axis to correct the position of the imaging surface IMG accompanying the magnification change. In this case, aperture stop STP is moved together with the second lens group G _72. Further, by moving the first lens group G ₇₁ toward the object side along the optical axis, focusing from an infinite distance object focusing state to a closest distance distance object focusing state is performed.

  Hereinafter, various numerical data on the zoom lens according to Example 7 will be shown.

Focal length of the entire zoom lens system = 3.09 (wide-angle end) to 31.12 (telephoto end)
F number (FNO) = 1.23 (wide-angle end) to 6.88 (telephoto end)
Half angle of view (ω) = 52.03 (wide-angle end) to 5.41 (telephoto end)
Focal length of the first lens group G ₇₁ (f 1) = − 9.07
Focal length of the second lens group G ₇₂ (f 2) = 14.59
Focal length of the third lens group G ₇₃ (f 3) = − 34.24
Focal length of the fourth lens group G ₇₄ = 17.08
Magnification ratio = 10.08

(Lens data)
r ₁ = 20.859
d ₁ = 0.50 nd ₁ = 1.88 d d ₁ = 40.81
r ₂ = 9.500
d ₂ = 7.87
r ₃ = −73.957
d ₃ = 0.50 nd ₂ = 1.64 d d ₂ = 55.45
r ₄ = 12.285
d ₄ = 1.44
r ₅ = 18.848 (aspheric surface)
d ₅ = 5.30 nd ₃ = 1.90 d d ₃ = 31.01
r ₆ = -20.815
d ₆ = 0.41
r ₇ = -17.927
d ₇ = 0.50 nd ₄ = 1.62 dd ₄ = 63.86
r ₈ = 15.963 (aspheric surface)
d ₈ = D (8) (variable)
r ₉ = 11.414 (aspheric surface)
d ₉ = 5.08 nd ₅ = 1.50 dd ₅ = 81.56
r ₁₀ = −23.827 (aspheric surface)
d ₁₀ = 0.71
r ₁₁ = ((aperture stop)
d ₁₁ = 1.57
r ₁₂ = 16.271
d ₁₂ = 0.83 nd ₆ = 1.80 d d ₆ = 29.84
r ₁₃ = 7.720
d ₁₃ = 4.82 nd ₇ = 1.44 d d ₇ = 95.10
r ₁₄ = -54.939
d ₁₄ = D (14) (variable)
r ₁₅ = -12.976
d ₁₅ = 0.50 nd ₈ = 1.62 d d ₈ = 36.30
r ₁₆ = 12.988
d ₁₆ = 1.13
r ₁₇ = 19.171
d ₁₇ = 1.59 nd ₉ = 1.85 d d ₉ = 32. 27
r ₁₈ = -57.591
d ₁₈ = D (18) (variable)
r ₁₉ = 41.241 (aspheric surface)
d ₁₉ = 2.53 nd ₁₀ = 1.50 d d ₁₀ = 81.56
r ₂₀ = −10.474 (aspheric surface)
d ₂₀ = D (20) (variable)
r ₂₁ = ∞
d ₂₁ = 1.50 nd ₁₁ = 1.52 dd ₁₁ = 64.20
r ₂₂ = ∞
d ₂₂ = 4.00
r ₂₃ = ((imaging plane)

Conic coefficient (k) and aspheric coefficient (A, B, C, D, E)
(Face 5)
k = 0,
A = 0,
B = -1. 10804 × 10 ⁻⁴ , C = 2.40067 × 10 ⁻⁶ ,
D = -2.802.48 x 10 ^-8 , E = 2.34615 x 10 ^-10
(Eighth)
k = 0,
A = 0,
B = -3.03764 x 10 ^-4 , C = 3.42411 x 10 ^-6 ,
D =-4.75443 x 10 ^-8 , E = 3.55623 x 10 ^-10
(9th side)
k = 0,
A = 0,
B = -9.31203 x 10 ^-5 , C = -4.35845 x 10 ^-7 ,
D = 3.02696 x 10 ^-9 , E =-5.65335 x 10 ^-11
(Ten 10)
k = 0,
A = 0,
B = 7.16629 x 10 ^-5 , C = -5.08309 x 10 ^-7 ,
D = 7.05728 × 10 ⁻⁹ , E = −5.04859 × 10 ⁻¹¹
(The 19th)
k = 0,
A = 0,
B = 3.31171 x 10 ^-4 , C = 2.53313 x 10 ^-5 ,
D = 7.07224 x 10 ^-8 , E = 2.98452 x 10 ^-8
(The 20th)
k = 0,
A = 0,
B = 5.29999 × 10 ^-4 , C = 6.53044 × 10 ^-5 ,
D = -3.24111 × 10 ^-6 , E = 1.60775 × 10 ^-7

(Modified data)
Wide-angle end Telephoto end
D (8) 36.54 1.51
D (14) 2.59 38.22
D (18) 0.53 9.92
D (20) 1.50 0.55

(Numeric values related to conditional expression (1))
| Β2T / β2W | = 8.18
.beta.2T: magnification at the telephoto end of the second lens group G ₇₂ .beta.2w: magnification at the wide-angle end of the second lens group G ₇₂

(Numeric values related to conditional expression (2))
β2W = -0.37

(Numeric values related to conditional expression (3))
β2T = -2.98

(Numeric values related to conditional expression (4))
βLT = 0.66
βLT: Magnification at the telephoto end of the lens unit (the fourth lens unit G ₇₄ ) arranged closest to the image side

(Numeric values related to conditional expression (5))
| F1 | /f2=0.62

(Numeric values related to conditional expression (6))
| F2 / f3 | = 0.43

(Numeric values related to conditional expression (7))
d d 1 p = 31.01
d d 1 p: Abbe number for the d-line of the positive lens (positive lens L ₇₁₃ ) included in the first lens group G ₇₁

(Numeric values related to conditional expression (8))
d d 1 n = 63. 86
d d1 n: Abbe number for the d-line of the negative lens (negative lens L ₇₁₄ ) contained in the first lens group G ₇₁

(Numeric values related to conditional expression (9))
d d 2 pa = 88.33
d d 2 pa: average value of Abbe number for the d-line of the positive lens included in the second lens group G ₇₂

(Numeric values related to conditional expression (10))
(R31 + R32) / (R31-R32) = 0.00
R31: third curvature of the object side surface of the most negative lens disposed on the object side L ₇₃₁ of lens group G ₇₃ radius R32: an image of the negative lens L ₇₃₁ most is located on the object side of the third lens group G ₇₃ Side curvature radius

(Numeric values related to conditional expression (11))
| X2 | ² / (| f1 | x f2) = 14.68
X2: Movement amount of second lens group G ₇₂ during zooming from the wide-angle end to the telephoto end (= 44.07)

(Numeric values related to conditional expression (12))
f2 / fLw = 0.62
fLw: synthetic focal length (= 23.70) at the wide-angle end of all lens units arranged in the third lens unit G _{73 and} after

  FIG. 14 is a diagram showing various aberrations of the zoom lens according to the seventh example. In the spherical aberration diagram, the vertical axis represents the f-number (indicated by FNO in the figure), the solid line represents d-line (λ = 587.56 nm), the short broken line represents g-line (λ = 435.84 nm), and the long broken line represents IR The characteristics of the wavelength corresponding to the line (λ = 850.00 nm) are shown. In the astigmatism diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line. In the astigmatism diagram, the solid line indicates the characteristic of the sagittal plane (indicated by S in the figure) and the broken line indicates the characteristic of the meridional plane (indicated by M in the figure). In the distortion aberration diagram, the vertical axis represents a half angle of view (denoted by ω in the figure), and shows the characteristic of the wavelength corresponding to the d-line.

In the numerical data in each of the above-described embodiments, r ₁ , r ₂ ,... Represent the radius of curvature of each lens and diaphragm surface, and d ₁ , d ₂ ,. thickness or their surface separations, nd _1, nd _2, ···· the d-line, such as the lenses (lambda = 587.56 nm) refractive index for, νd _1, νd _2, ···· each lens, etc. Shows the Abbe number for the d-line (λ = 587.56 nm) of And all units of length are "mm", and all units of angle are "°".

  In each of the aspheric surface shapes, the height in the direction perpendicular to the optical axis is H, the displacement amount in the optical axis direction at height H when the lens surface top is the origin is X, the paraxial radius of curvature is R, When the conical coefficients are k, 2nd, 4th, 6th, 8th and 10th aspheric coefficients are A, B, C, D and E, respectively, and the traveling direction of light is positive, the following equations Is represented by

  As described in each of the above embodiments, according to the present invention, the small-sized, large aperture, high optical power with high optical performance capable of satisfactorily correcting various aberrations over the entire variable power range is provided. A zoom lens can be realized. In particular, by satisfying the conditional expressions (7), (8) and (9), it is possible to realize a zoom lens having high optical performance capable of photographing not only the visible light region but also the near infrared light region. Can. Furthermore, this zoom lens can further improve the optical performance by arranging a lens with aspheric surface formed appropriately and a cemented lens.

  As described above, the zoom lens according to the present invention is useful for a compact imaging device on which a solid-state imaging device such as a CCD or a CMOS is mounted, and is particularly suitable for an imaging device that requires high optical performance.

_{G 11, G 21, G 31} , G 41, G 51, G 61, G 71 first lens group _{G 12, G 22, G 32} , G 42, G 52, G 62, G 72 the second lens group G _{13 , G 23, G 33, G} 43, G 53, G 63, G 73 the third lens group G ₇₄ fourth lens group _{L 111, L 112, L 114} , L 122, L 131, L 211, L 212, L ₂₁₄ , L ₂₂₂ , L ₂₃₁ , L ₃₁₁ , L ₃₁₂ , L ₃₁₄ , L ₃₂₂ , L ₃₃₁ , L ₄₁₁ , L ₄₁₂ , L ₄₁₄ , L ₄₂₂ , L ₄₃₁ , L ₅₁₁ , L ₅₁₂ , L ₅₁₄ , L ₅₂₂ , L ₅₃₁ , L ₆₁₁ , L ₆₁₂ , L ₆₁₄ , L ₆₂₂ , L ₆₃₁ , L ₇₁₁ , L ₇₁₁ , L ₇₁₂ , L ₇₁₄ , L ₇₂₂ , L ₇₃₁ negative lens L ₁₁₃ , L ₁₂₁ , L ₁₂₃ , L ₁₃₂ , L ₁₃₃ , L ₂₁₃ , L ₂₂₁ , L ₂₂₃ , L ₂₃₂ , L ₂₃₃ , L ₃₁₃ , L ₃₂₁ , L ₃₂₃ , L ₃₃₂ , L ₃₃₃ , L ₄₁₃ , L ₄₂₁ , L ₄₂₃ , L ₄₃₂ , L ₄₃₃ , L ₅₁₃ , L ₅₂₁ , L ₅₂₃ , L ₅₃₂ , L ₅₃₃ , L ₆₁₃ , L ₆₂₁ , L ₆₂₃ , L ₆₃₂ , L ₆₃₃ , L ₇₁₃ , L ₇₂₁ , L ₇₂₃ , L ₇₃₂ , L ₇₄₁ positive lens STP aperture stop CG cover glass IMG imaging surface

Claims (12)

A first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group, which are arranged in order from the object side, and the distance between the lens groups on the optical axis A zoom lens that changes magnification by changing
The second lens unit includes a positive lens, a negative lens, and a positive lens, which are disposed in order from the object side.
In the third lens group, a negative lens is disposed closest to the object side, and
A zoom lens characterized by satisfying the following conditional expression.
(1) 2.8 ≦ | β2T / β2W | ≦ 12.0
(2)-0.5 β β 2 W −-0.1
(5) 0.35 ≦ | f1 | /f2≦0.85
Here, β2T represents the magnification of the second lens group at the telephoto end, and β2W represents the magnification of the second lens group at the wide angle end. f1 represents the focal length of the first lens group, and f2 represents the focal length of the second lens group. The zoom is performed by moving the first lens group along the optical axis,
By moving the second lens unit and the subsequent lens units along the optical axis, the image plane variation accompanying the magnification change is corrected.
The focusing from an infinite distance object focusing state to a closest distance distance object focusing state is performed by moving the first lens group to the object side along the optical axis. Zoom lens. The zoom lens according to claim 1, which satisfies the following conditional expression.
(3) −4.50 ≦ β2T ≦ −1.45
Here, β2T represents the magnification of the second lens group at the telephoto end. The zoom lens according to any one of claims 1 to 3, which satisfies the following conditional expression.
(4) 0.3 ≦ βLT ≦ 1.0
Here, βLT represents the magnification at the telephoto end of the lens unit disposed closest to the image side. An aperture stop defining a predetermined aperture in the second lens group;
The zoom lens according to any one of claims 1 to 4, wherein the aperture stop moves together with the second lens unit from the image side to the object side during zooming from the wide-angle end to the telephoto end. The zoom lens according to any one of claims 1 to 5, which satisfies the conditional expression shown below.
(6) 0.2 ≦ | f2 / f3 | ≦ 1.0
Here, f2 represents the focal length of the second lens group, and f3 represents the focal length of the third lens group. The zoom lens according to any one of claims 1 to 6, wherein the conditional expression shown below is satisfied.
(9) d d 2 pa 6 68.0
Here, ν d 2 pa represents the average value of Abbe numbers for the d-line of the positive lens included in the second lens group.   The first lens group according to any one of claims 1 to 7, wherein a negative lens, a negative lens, and a positive lens are sequentially arranged in order from the object side. Zoom lens.   The zoom lens according to any one of claims 1 to 8, wherein the third lens group is configured by sequentially arranging a negative lens and a positive lens in order from an object side. The negative lens disposed on the most object side of the third lens group has a concave surface facing the object side,
The zoom lens according to any one of claims 1 to 9, which satisfies the following conditional expression.
(10)-1.5 <(R31 + R32) / (R31-R32) <0.3
However, R31 is the curvature radius of the object side surface of the negative lens disposed on the most object side of the third lens group, and R32 is the curvature of the image side surface of the negative lens disposed on the most object side of the third lens group Indicates the radius. The zoom lens according to any one of claims 1 to 10, which satisfies the following conditional expression.
(11) 4.5 ≦ | X2 | ² /(|f1|×f2)≦16.5
Here, X2 indicates the amount of movement of the second lens unit during zooming from the wide-angle end to the telephoto end, f1 indicates the focal length of the first lens unit, and f2 indicates the focal length of the second lens unit. The zoom lens according to any one of claims 1 to 11, which satisfies the following conditional expression.
(12) 0.3 ≦ f2 / fLw ≦ 1.1
Here, f2 represents the focal length of the second lens group, and fLw represents the combined focal length at the wide-angle end of all the lens groups disposed after the third lens group.

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