# Patent

## Title
Zoom lens and image pickup apparatus including the same

## Abstract

A zoom lens includes in order from object side to image side: a positive first lens unit that does not move for zooming; a negative second lens unit that moves during zooming; and a positive N-th lens unit that does not move for zooming, the N-th lens unit being arranged closest to the image side. The first lens unit includes, in order from object side to image side: a negative first sub-lens unit that does not move for focusing; a positive second sub-lens unit that moves along an optical axis during focusing; and a positive third sub-lens unit that does not move for focusing. Focal length of the first lens unit, focal length at wide angle end of the zoom lens, and lateral magnification at wide angle end satisfy predetermined conditions.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus including the same, which are suitable for a broadcasting television camera, a movie camera, a video camera, a digital still camera, a monitoring camera, and a silver-halide film camera, for example.
2. Description of the Related Art
In recent years, a zoom lens having a wide angle of field, a high zoom ratio, and high optical performance is required for an image pickup apparatus such as a television camera, a movie camera, a silver-halide film camera, a digital camera, or a video camera. There has been known, as a zoom lens having a wide angle of field and a high zoom ratio, a four-unit zoom lens including a first lens unit having a positive refractive power, a second lens unit having a negative refractive power that is used for zooming, a third lens unit having a negative refractive power that is used to correct image plane variation accompanying zooming, and a fourth lens unit having a positive refractive power that is used for image formation (Japanese Patent Application Laid-Open Nos. H09-015501 and 2004-341237).
In Japanese Patent Application Laid-Open No. H09-015501, there is disclosed a zoom lens having a zoom ratio of approximately 8 and a field angle of photography at a wide angle end of approximately 87°. In Japanese Patent Application Laid-Open No. 2004-341237, there is disclosed a zoom lens having a zoom ratio of approximately 2.9 and a field angle of photography (an angular field of view) at a wide angle end of approximately 94°.
In the four-unit zoom lens having the structure described above, it is relatively easy to achieve the increased wide angle of field. However, in order to achieve both the high optical performance and the reduction in size of the four-unit zoom lens, it is important to appropriately set the arrangement of the refractive powers of the lenses. In particular, in the lens unit closest to an object side, an off-axis ray passes through a position farthest from the optical axis. Therefore, in order to achieve both the high optical performance and the reduction in size, it is important to appropriately set the refractive power and the structure of the lens unit closest to the object side. In addition, the lens unit closest to the image side plays a role of determining sizes of all lenses closer to the object side than the lens unit. Therefore, in order to achieve both the high optical performance and the reduction in size, it is important to appropriately set the lateral magnification of the lens unit closest to the image side. Unless those conditions are approximately set, it becomes difficult to obtain the zoom lens having the wide angle of field, the high zoom ratio, and the high optical performance over the entire zoom range.
The zoom lens disclosed in each of Japanese Patent Application Laid-Open Nos. H09-015501 and 2004-341237 is assumed to be applied to a relatively small image pickup element for a television camera. When the zoom lens is applied to an image pickup element that has been increased in size in recent years, the lens is also increased in size in proportion to the enlargement of the image pickup element.
SUMMARY OF THE INVENTION
The present invention provides a zoom lens having a wide angle of field, a high zoom ratio, high optical performance over an entire zoom range, and good zoom action, and provides an image pickup apparatus including the zoom lens.
According to one embodiment of the present invention, there is provided a zoom lens, including, in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; and an N-th lens unit having a positive refractive power that does not move for zooming, the n-th lens unit being arranged closest to the image side, in which the first lens unit includes, in order from the object side to the image side: a first sub-lens unit having a negative refractive power that does not move for focusing; a second sub-lens unit having a positive refractive power that moves along an optical axis during focusing; and a third sub-lens unit having a positive refractive power that does not move for focusing, and the following conditional expressions are satisfied:

1.5<f1/fw<3.5; and

−2.70<βnw<−1.45,

where f1 represents a focal length of the first lens unit, fw represents a focal length at a wide angle end of the zoom lens, and βnw represents a lateral magnification at a wide angle end.

According to one embodiment of the present invention, it is possible to provide the zoom lens having a wide angle of field, a high zoom ratio, and high optical performance over the entire zoom range, and to provide the image pickup apparatus including the zoom lens.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a lens cross-sectional view when focusing on an infinite object at a wide angle end according to Numerical Embodiment 1 of the present invention.
FIG. 2A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 1.
FIG. 2B is an aberration diagram when focusing on an infinite object at an intermediate zoom position according to Numerical Embodiment 1.
FIG. 2C is an aberration diagram when focusing on an infinite object at a telephoto end according to Numerical Embodiment 1.
FIG. 3 is a lens cross-sectional view when focusing on an infinite object at the wide angle end according to Numerical Embodiment 2 of the present invention.
FIG. 4A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 2.
FIG. 4B is an aberration diagram when focusing on an infinite object at the intermediate zoom position according to Numerical Embodiment 2.
FIG. 4C is an aberration diagram when focusing on an infinite object at the telephoto end according to Numerical Embodiment 2.
FIG. 5 is a lens cross-sectional view when focusing on an infinite object at the wide angle end according to Numerical Embodiment 3 of the present invention.
FIG. 6A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 3.
FIG. 6B is an aberration diagram when focusing on an infinite object at the intermediate zoom position according to Numerical Embodiment 3.
FIG. 6C is an aberration diagram when focusing on an infinite object at the telephoto end according to Numerical Embodiment 3.
FIG. 7 is a lens cross-sectional view when focusing on an infinite object at the wide angle end according to Numerical Embodiment 4 of the present invention.
FIG. 8A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 4.
FIG. 8B is an aberration diagram when focusing on an infinite object at the intermediate zoom position according to Numerical Embodiment 4.
FIG. 8C is an aberration diagram when focusing on an infinite object at the telephoto end according to Numerical Embodiment 4.
FIG. 9 is a lens cross-sectional view when focusing on an infinite object at the wide angle end according to Numerical Embodiment 5 of the present invention.
FIG. 10A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 5.
FIG. 10B is an aberration diagram when focusing on an infinite object at the intermediate zoom position according to Numerical Embodiment 5.
FIG. 10C is an aberration diagram when focusing on an infinite object at the telephoto end according to Numerical Embodiment 5.
FIG. 11 is a lens cross-sectional view when focusing on an infinite object at the wide angle end according to Numerical Embodiment 6 of the present invention.
FIG. 12A is an aberration diagram when focusing on an infinite object at the wide angle end according to Numerical Embodiment 6.
FIG. 12B is an aberration diagram when focusing on an infinite object at the intermediate zoom position according to Numerical Embodiment 6.
FIG. 12C is an aberration diagram when focusing on an infinite object at the telephoto end according to Numerical Embodiment 6.
FIG. 13 is a schematic diagram of a main part of an image pickup apparatus of the present invention.



DESCRIPTION OF THE EMBODIMENT
Now, an embodiment of the present invention is described in detail with reference to the attached drawings. A zoom lens according to each of Embodiments 1 to 5 of the present invention includes, in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; a third lens unit having a negative refractive power that moves during zooming; and a fourth lens unit having a positive refractive power that does not move for zooming.
A zoom lens according to Embodiment 6 of the present invention includes, in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; a third lens unit having a negative refractive power that moves during zooming; a fourth lens unit having a negative refractive power that moves during zooming; and a fifth lens unit having a positive refractive power that does not move for zooming.
The expression that “a lens unit does not move for zooming” means herein that the lens unit is not driven for a purpose of zooming, but the lens unit may move for focusing during zooming if zooming and focusing are performed simultaneously.
FIG. 1 is a lens cross-sectional view of a zoom lens according to Embodiment 1 (Numerical Embodiment 1) of the present invention when focusing on an infinite object at a wide angle end (focal length f=18.00 nm). FIGS. 2A, 2B, and 2C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=63.00 mm), and at a telephoto end (focal length f=180.00 mm) when focusing on an infinite object according to Numerical Embodiment 1. Here, the focal length is a value of this numerical embodiment expressed in millimeters. The same is true for the following embodiments.
FIG. 3 is a lens cross-sectional view of a zoom lens according to Embodiment 2 (Numerical Embodiment 2) of the present invention at a wide angle end (focal length f=15.00 mm) when focusing on an infinite object. FIGS. 4A, 4B, and 4C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=35.00 mm), and at a telephoto end (focal length f=75.00 mm) when focusing on an infinite object according to Numerical Embodiment 2.
FIG. 5 is a lens cross-sectional view of a zoom lens according to Embodiment 3 (Numerical Embodiment 3) of the present invention at a wide angle end (focal length f=20.00 mm) when focusing on an infinite object. FIGS. 6A, 6B, and 6C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=60.00 mm), and at a telephoto end (focal length f=160.00 mm) when focusing on an infinite object according to Numerical Embodiment 3.
FIG. 7 is a lens cross-sectional view of a zoom lens according to Embodiment 4 (Numerical Embodiment 4) of the present invention at a wide angle end (focal length f=19.00 mm) when focusing on an infinite object. FIGS. 8A, 8B, and 8C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=45.00 mm), and at a telephoto end (f=95.00 mm) when focusing on an infinite object according to Numerical Embodiment 4.
FIG. 9 is a lens cross-sectional view of a zoom lens according to Embodiment 5 (Numerical Embodiment 5) of the present invention at a wide angle end (focal length f=14 mm) when focusing on an infinite object. FIGS. 10A, 10B, and 10C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=28.00 mm), and at a telephoto end (focal length f=56.00 mm) when focusing on an infinite object according to Numerical Embodiment 5.
FIG. 11 is a lens cross-sectional view of a zoom lens according to Embodiment 6 (Numerical Embodiment 6) of the present invention at a wide angle end (focal length f=18.50 mm) when focusing on an infinite object. FIGS. 12A, 12B, and 12C are aberration diagrams respectively at the wide angle end, at an intermediate zoom position (focal length f=45.00 mm), and at a telephoto end (focal length f=120.25 mm) when focusing on an infinite object according to Numerical Embodiment 6.
FIG. 13 is a schematic diagram of a main part of an image pickup apparatus of the present invention.
In each lens cross-sectional view, the left side is a subject (object) side (front), and the right side is the image side (rear). In the lens cross-sectional view, a first lens unit (front lens unit) U1 has a positive refractive power and does not move for zooming. A focus lens unit U11 in the first lens unit U1 moves toward the object side when focusing from an infinite object to an object at a close range. A fixed lens unit U12 or U13 in the first lens unit U1 does not move for focusing. In FIGS. 1, 3, 5, 7, and 9 (Embodiments 1 to 5), a second lens unit U2 and a third lens unit U3 each has a negative refractive power and moves during zooming. The two lens units: the second lens unit U2; and the third lens unit U3 are lens units which move during zooming. A fourth lens unit U4 (relay lens unit) has a positive refractive power and an imaging action, and does not move for zooming. In FIG. 11 (Embodiment 6), a second lens unit U2, a third lens unit U3, and a fourth lens unit U4 each have a negative refractive power and moves during zooming. The three lens units: the second lens unit U2; the third lens unit U3; and the fourth lens unit U4 are lens units which move during zooming. In addition, a fifth lens unit U5 (relay lens unit) has a positive refractive power and an imaging action, and does not move for zooming.
A stop (aperture stop) SP is arranged. When used as an image pickup optical system for a broadcasting television camera, a movie camera, a video camera, or a digital still camera, an image pickup surface I corresponds to an image pickup surface of a solid-state image pickup element (photoelectric transducer) or the like for receiving an image formed by the zoom lens and converting light to electricity. When used as an image pickup optical system for a film camera, the image pickup surface I corresponds to a film surface on which the image formed by the zoom lens is exposed.
In the aberration diagrams, a straight line, a two-dot chain line, a dashed line, and a broken line in a spherical aberration indicate an e-line, a g-line, a C-line, and an F-line, respectively. A broken line and a solid line in astigmatism indicate a meridional image plane and a sagittal image plane, respectively. In addition, a two-dot chain line, a dashed line, and a broken line in a lateral chromatic aberration indicate a g-line, a C-line, and an F-line, respectively. Symbol ω represents a half angle of field, and a symbol Fno represents an F number. Note that, in the following embodiments, the case where a lens unit for zooming is located at the shortest focal length side is referred to as “wide angle end”, and the case where a lens unit for zooming is located at the longest focal length side is referred to as “telephoto end”.
The zoom lens according to each embodiment of the present invention includes, in order from an object side to an image side: a first lens unit U1 having a positive refractive power that does not move for zooming; a second lens unit U2 having a negative refractive power that moves during zooming; and an N-th lens unit UN having a positive refractive power that does not move for zooming, the N-th lens unit being arranged closest to the image side. The first lens unit U1 includes, in order from the object side to the image side: a first sub-lens unit U11 having a negative refractive power that does not move for focusing; a second sub-lens unit U12 having a positive refractive power that moves along an optical axis during focusing; and a third sub-lens unit U13 having a positive refractive power that does not move for focusing. The following conditional expressions are satisfied.

1.5<f1/fw<3.5  (1)

−2.70<βnw<−1.45  (2)

In the expressions, f1 represents a focal length of the first lens unit U1, fw represents a focal length at a wide angle end of the entire system (zoom lens), and βnw represents a lateral magnification of the N-th lens unit UN at a wide angle end. Here, βnw represents a magnification of the N-th lens unit for a ray from an object which is in focus at wide angle end. That is, any magnification of the N-th lens unit determined based on rays from an object at closest end or at infinity can be set for βnw as long as the object is in focus. For example, a magnification of the N-th lens unit determined based on rays from an object at infinity on which the zoom lens of the present invention focuses at wide angle end can be βnw.

The conditional expression (1) defines a ratio of the focal length of the first lens unit U1 to the focal length at the wide angle end of the first lens unit U1. In the zoom lens of each embodiment, the focal length of the first lens unit U1 is an important factor for achieving both the high optical performance and the reduction in size. By satisfying the conditional expression (1), a height of off-axis ray that passes through the first lens unit U1 at the wide angle end can be defined, and the various aberrations can be satisfactorily corrected while the increase in size of the lens is suppressed.
If the condition of an upper limit of the conditional expression (1) is not satisfied, the refractive power of the first lens unit U1 is reduced, and the height of the off-axis ray that passes through the first lens unit U1 is increased. As a result, the lens is increased in size. On the other hand, if the condition of a lower limit of the conditional expression (1) is not satisfied, the refractive power of the first lens unit U1 is increased. As a result, in particular, a chromatic aberration and the various aberrations on the telephoto side become difficult to correct.
The conditional expression (2) defines a lateral magnification of the N-th lens unit UN. In the zoom lens of each embodiment, in order to suppress an influence on the performance, which is caused by the increase in size and the manufacturing error of the lens, the lateral magnification of the N-th lens unit UN is appropriately set. By satisfying the conditional expression (2), the zoom lens that is superior in manufacturability can be obtained while the increase in size of the lens is suppressed.
If the condition of an upper limit of the conditional expression (2) is not satisfied, the size of each lens before the N-th lens unit UN is increased, and particularly, an effective diameter (an effective aperture) of the first lens unit U1 becomes large. On the other hand, if the condition of a lower limit of the conditional expression (2) is not satisfied, an enlargement ratio of each lens before the N-th lens unit UN is increased. As a result, the correction of the various aberrations, particularly, the correction of the chromatic aberration on the telephoto side becomes difficult. In addition, the influence of the manufacturing error on the performance becomes large, and hence the performance deterioration due to the manufacturing variations becomes large.
It is more preferred to set the numerical value ranges of the conditional expressions (1) and (2) as follows.

2.0<f1/fw<2.7  (1a)

−2.40<βnw<−1.55  (2a)

By satisfying the conditions described above, according to each embodiment of the present invention, it is possible to provide the zoom lens that is reduced is size and weight for which the aberration correction is satisfactorily carried out over the entire zoom range.
In each embodiment, it is more preferred that the following conditional expressions be satisfied:

−1.5<f11/f1<−0.9  (3)

−1.5<f13/f11<−0.9  (4)

In the expressions, f11 represents a focal length of a first sub-lens unit U11 and f13 represents a focal length of a third sub-lens unit U13.

The conditional expression (3) defines a ratio of the focal length of the first lens unit U1 to the focal length of the first sub-lens unit U11.
If the condition of an upper limit of the conditional expression (3) is not satisfied, the focal length of the first sub-lens unit U11 becomes relatively short. As a result, the suppression of the variation in various off-axis aberrations accompanying the zooming on the wide angle side, particularly, the suppression of distortion and curvature of field becomes difficult. On the other hand, if the condition of a lower limit of the conditional expression (3) is not satisfied, the focal length of the first sub-lens unit U11 becomes relatively long. As a result, the lens diameter of the first lens unit U1 becomes large, and hence the wider angle becomes difficult to attain. In addition, it also becomes difficult to suppress the change in image field caused at the time of the focusing.
The conditional expression (4) defines a ratio of the focal length of the first sub-lens unit U11 to the focal length of the third sub-lens unit U13.
If the condition of an upper limit of the conditional expression (4) is not satisfied, the focal length of the first sub-lens unit U11 becomes relatively long. As a result, a principal point of the first lens unit U1 becomes difficult to approach the image side, the lens diameter of the first lens unit U1 becomes large, and hence the wider angle becomes difficult to attain. On the other hand, if the condition of a lower limit of the conditional expression (4) is not satisfied, the focal length of the first sub-lens unit U11 becomes relatively short. This leads to an increase in the number of lenses of the first sub-lens unit U11, and the lens diameter of the first lens unit U1 becomes large, and hence the wider angle becomes difficult to attain.
In each of Embodiments 1 to 5, it is more preferred that the following conditional expression be satisfied.

−3.0<f1/f2<−1.5  (5)

In the expression, f2 represents a focal length of the second lens unit U2.

The conditional expression (5) defines a ratio of the focal length of the first lens unit U1 to the focal length of the second unit U2.
If the condition of an upper limit of the conditional expression (5) is not satisfied, the focal length of the first lens unit U1 becomes relatively short. As a result, the correction of the various aberrations, particularly, the correction of the chromatic aberration on the telephoto side becomes difficult. In addition, the influence of the manufacturing error on the performance becomes large, and hence the performance deterioration due to the manufacturing variations becomes large.
If the condition of a lower limit of the conditional expression (5) is not satisfied, the focal length of the first lens unit U1 becomes relatively long. As a result, the lens diameter of the first lens unit U1 is enlarged, and hence the wider angle becomes difficult to attain. In addition, it also becomes difficult to suppress the change in image field caused at the time of the focusing.
In Embodiment 6, it is more preferred that the zoom lens include a third lens unit U3 having a negative lens unit that moves during zooming, and the following conditional expression be satisfied.

−3.0<f1/f23<−1.5  (6)

In the expression, f23 represents a combined focal length at a wide angle end of the second lens unit U2 and the third lens unit U3.

The conditional expression (6) defines a ratio of the focal length of the first lens unit U1 to the combined focal length f23 at the wide angle end of the second lens unit U2 and the third lens unit U3.
If the condition of an upper limit of the conditional expression (6) is not satisfied, the focal length of the first lens unit U1 becomes relatively short. As a result, the correction of the various aberrations, particularly, the correction of the chromatic aberration on the telephoto side becomes difficult. In addition, the influence of the manufacturing error on the performance becomes large, and hence the performance deterioration due to the manufacturing variations becomes large.
If the condition of a lower limit of the conditional expression (6) is not satisfied, the focal length of the first lens unit U1 becomes relatively long. As a result, the lens diameter of the first lens unit U1 is enlarged, and hence the wider angle becomes difficult to attain. In addition, it also becomes difficult to suppress the change in image field caused at the time of the focusing.
In each embodiment, it is more preferred that the second lens unit U2 include at least one aspherical surface. When the aspherical surface is applied to a surface having a positive refractive power, the aspherical surface preferably has such a shape that the positive refractive power is increased toward the periphery from the optical axis, while when the aspherical surface is applied to a surface having a negative refractive power, the aspherical surface preferably has such a shape that the negative refractive power is decreased toward the periphery from the optical axis. As a result, the suppression of the various off-axis aberrations on the wide angle side, particularly, the correction of the zoom variation due to the distortion and the curvature of field becomes easy.
It is more preferred to set the numerical value ranges of the conditional expressions (3) to (6) as follows.

−1.30<f11/f1<−1.10  (3a)

−1.35<f13/f11<−1.10  (4a)

−2.05<f1/f2<−1.60  (5a)

−2.05<f1/f23<−1.60  (6a)

Next, features of a lens configuration of each embodiment are described.
In Embodiment 1, the first lens unit U1 corresponds to a first lens surface to a twenty-first lens surface. The second lens unit U2 corresponds to a twenty-second lens surface to a thirty-first lens surface. The third lens unit U3 corresponds to a thirty-second lens surface to a thirty-fourth lens surface. The fourth lens unit U4 corresponds to a thirty-sixth lens surface to a fifty-third lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 substantially reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 1 satisfies all the conditional expressions (1) to (5). Embodiment 1 achieves a wider angle of field having a higher zoom ratio of 10.00 and a field angle of photography (angular field of view) of 81.65° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
In Embodiment 2, the first lens unit U1 corresponds to a first lens surface to an eighteenth lens surface. The second lens unit U2 corresponds to a nineteenth lens surface to a twenty-fifth lens surface. The third lens unit U3 corresponds to a twenty-sixth lens surface to a twenty-eighth lens surface. The fourth lens unit U4 corresponds to a thirtieth lens surface to a forty-eighth lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 substantially reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 2 satisfies all the conditional expressions (1) to (5). Embodiment 2 achieves a wider angle of field having a higher zoom ratio of 5.00 and a field angle of photography (angular field of view) of 92.06° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
In Embodiment 3, the first lens unit U1 corresponds to a first lens surface to an eighteenth lens surface. The second lens unit U2 corresponds to a nineteenth lens surface to a twenty-seventh lens surface. The third lens unit U3 corresponds to a twenty-eighth lens surface to a thirtieth lens surface. The fourth lens unit U4 corresponds to a thirty-second lens surface to a fifty-first lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 substantially reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 3 satisfies all the conditional expressions (1) to (5). Embodiment 3 achieves a wider angle of field having a higher zoom ratio of 8.00 and a field angle of photography (angular field of view) of 75.73° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
In Embodiment 4, the first lens unit U1 corresponds to a first lens surface to a fifteenth lens surface. The second lens unit U2 corresponds to a sixteenth lens surface to a twenty-third lens surface. The third lens unit U3 corresponds to a twenty-fourth lens surface to a twenty-sixth lens surface. The fourth lens unit U4 corresponds to a twenty-eighth lens surface to a forty-fifth lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 substantially reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 4 satisfies all the conditional expressions (1) to (5). Embodiment 4 achieves a wider angle of field having a higher zoom ratio of 5.00 and a field angle of photography (angular field of view) of 78.60° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
In Embodiment 5, the first lens unit U1 corresponds to a first lens surface to a nineteenth lens surface. The second lens unit U2 corresponds to a twentieth lens surface to a twenty-seventh lens surface. The third lens unit U3 corresponds to a twenty-eighth lens surface to a thirtieth lens surface. The fourth lens unit U4 corresponds to a thirty-second lens surface to a forty-eighth lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 substantially reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 5 satisfies all the conditional expressions (1) to (5). Embodiment 5 achieves a wider angle of field having a higher zoom ratio of 4.00 and a field angle of photography (angular field of view) of 96.00° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
In Embodiment 6, the first lens unit U1 corresponds to a first lens surface to a twenty-first lens surface. The second lens unit U2 corresponds to a twenty-second lens surface to a twenty-sixth lens surface. The third lens unit U3 corresponds to a twenty-seventh lens surface to a thirtieth lens surface. The fourth lens unit U4 corresponds to a thirty-first lens surface to a thirty-third lens surface. The fifth lens unit U5 corresponds to a thirty-fifth lens surface to a fifty-second lens surface.
During the zooming from the wide angle end to the telephoto end, when the second lens unit U2 linearly moves to the image side, the third lens unit U3 also moves substantially linearly to the image side. The second lens unit U2 and the third lens unit U3 move in such a direction that an interval between the second lens unit U2 and the third lens unit U3 increases during the zooming from the wide angle end to the telephoto end. In addition, the fourth lens unit U4 substantially linearly reciprocates while drawing a convex locus on the object side.
As shown in Table 1 below, Numerical Embodiment 6 satisfies all the conditional expressions (1) to (4) and (6). Embodiment 6 achieves a wider angle of field having a higher zoom ratio of 6.50 and a field angle of photography (angular field of view) of 80.10° at the wide angle end. Further, in the entire zoom range, high optical performance is obtained in which various aberrations are appropriately corrected.
As described above, according to each embodiment, the refractive power arrangement of each lens unit, the movement locus of the moving lens unit for zooming, and the like are appropriately defined. Thus, it is possible to obtain the zoom lens having a higher zoom ratio and a wider angle of field, in which various aberrations are appropriately corrected.
FIG. 13 is a schematic diagram of a main part of an image pickup apparatus (TV camera system) employing the zoom lens of Embodiments 1 to 6 as an imaging optical system. FIG. 13 illustrates a zoom lens 101 according to any one of Embodiments 1 to 6 and a camera 124. The zoom lens 101 can be mounted into and removed from the camera 124. The zoom lens 101 is mounted into the camera 124 to form an image pickup apparatus 125. The zoom lens 101 includes a first lens unit F, a zoom section LZ, and an N-th lens unit R for image formation. The first lens unit U1F includes a focus lens unit. The first lens unit F includes a lens unit U12 for focusing that moves on the optical axis during the focusing, and a lens unit U11 that does not move for focusing.
The zoom section LZ includes a second lens unit U2 and a third lens unit U3 that move on the optical axis during zooming in each of Embodiments 1 to 6, and an N-th lens unit U4 closest to the image side that does not move for zooming. The zoom lens 101 also includes an aperture stop SP, and driving mechanisms 114 and 115, such as helicoids and cams, for driving in the optical axis direction the second sub-lens unit U12 and the zoom section LZ, respectively.
The image pickup apparatus 125 includes motors (driving units) 116 to 118 for electrically driving the driving mechanisms 114 and 115 and the aperture stop SP. The image pickup apparatus 125 also includes detectors 119 to 121, such as an encoder, a potentiometer, or a photo-sensor, which are configured to detect the positions of the second sub-lens unit U12 and the zoom section LZ on the optical axis, and the aperture diameter of the aperture stop SP. In addition, the camera 124 includes a glass block 109, which corresponds to an optical filter inside the camera 124. Further, the camera 124 includes a solid-state image pickup element (photoelectric transducer) 110, such as a charge-coupled device (CCD) sensor or a complementary metal-oxide semiconductor (CMOS) sensor. The solid-state image pickup element 110 is configured to receive an object image formed by the zoom lens 101.
Further, central processing units (CPUs) 111 and 122 control various types of driving of the camera 124 and the zoom lens 101, respectively. Through application of the zoom lens according to the present invention to a TV camera as described above, an image pickup apparatus having high optical performance is implemented.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
Now, Numerical Embodiments 1 to 6, corresponding to Embodiments 1 to 6 of the present invention, are described. In each of Numerical Embodiments, i represents an order of a surface from the object side, ri represents a curvature radius of an i-th surface from the object side, di represents an interval between the i-th surface and the (i+1)th surface from the object side, and ndi and νdi respectively represent a refractive index and an Abbe constant of the i-th optical member. An aspherical surface is represented by “*” next to the surface number. Table 1 shows correspondences between each embodiment and the conditional expressions described above.
The aspherical shape is expressed by the following expression:




  X
  =
  
    
      
        
          H
          2
        
        /
        R
      
      
        1
        +
        
          
            1
            -
            
              
                (
                
                  1
                  +
                  k
                
                )
              
              ⁢
              
                
                  (
                  
                    H
                    /
                    R
                  
                  )
                
                2
              
            
          
        
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      4
      ⁢
      
        
      
      ⁢
      
        H
        4
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      6
      ⁢
      
        
      
      ⁢
      
        H
        6
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      8
      ⁢
      
        
      
      ⁢
      
        H
        8
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      10
      ⁢
      
        
      
      ⁢
      
        H
        10
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      12
      ⁢
      
        
      
      ⁢
      
        H
        12
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      14
      ⁢
      
        
      
      ⁢
      
        H
        14
      
    
    +
    
      A
      ⁢
      
        
      
      ⁢
      16
      ⁢
      
        
      
      ⁢
      
        H
        16
      
    
  




where an X axis corresponds to the optical axis, an H axis corresponds to an axis perpendicular to the optical axis, a traveling direction of light corresponds to a positive direction, R represents a paraxial curvature radius, k represents a conic constant, A4, A6, A8, A10, A12, A14, and A16 each represent an aspherical coefficient, and “e-Z” means “×10−Z”.

In each of Embodiments 1 to 5, two lens units move during the zooming, and hence when the movement locus of one lens unit is determined, the movement locus of the other lens unit is also determined. However, in Embodiment 6, three lens units move during the zooming, and hence even when the movement locus of one lens unit is determined, the movement loci of the other two lens units cannot be uniquely determined. Therefore, Embodiment 6 shows the movement loci of the second lens unit and the third lens unit.
The movement locus is expressed by the following expression:

fj(y)=Bj1y+Bj2y2+Bj3y3+Bj4y4+Bj5y5+Bj6y6 

where j represents a number of a lens unit, fj(y) represents a movement amount in the optical axis direction, a traveling direction of light corresponds to a positive direction, y represents the amount of movement from the wide angle end to the telephoto end as 1, and Bj1, Bj2, Bj3, Bj4, Bj5, and Bj6 represent movement coefficients, respectively.

Numerical Embodiment 1










Unit mm







Surface data














Surface





Effective
Focal


Number
r
d
nd
vd
θgF
diameter
length





 1*
107.07477
3.50000
1.772499
49.60
0.5521
94.999
−94.002


 2
42.77453
29.44657



74.747



 3
−111.18408
2.00000
1.772499
49.60
0.5521
74.020
−86.187


 4
169.27879
0.19853



73.831



 5
111.15261
6.53424
1.959060
17.47
0.6599
74.684
162.844


 6
362.57244
4.83576



74.310



 7*
402.11683
9.52789
1.620411
60.29
0.5426
73.646
143.795


 8
−114.18218
7.22051



73.330



 9
273.53589
11.14023
1.496999
81.54
0.5374
67.740
131.565


10
−85.09102
1.32713



67.551



11
−74.32274
2.00000
1.805181
25.42
0.6161
67.398
−164.470


12
−169.44313
1.00002



68.351



13
2516.57481
1.80000
1.850259
32.27
0.5929
68.012
−98.133


14
81.30733
11.18444
1.438750
94.93
0.5343
67.555
149.790


15
−332.76941
0.20010



67.981



16
7491.62170
5.08975
1.496999
81.54
0.5374
68.578
390.027


17
−199.54524
0.20000



69.118



18
1595.58460
5.39098
1.595220
67.74
0.5442
69.947
305.715


19
−205.94799
0.20000



70.201



20
216.17076
10.28079
1.730000
49.00
0.5575
70.182
104.355


21
−116.13168
(Variable)



69.897



22*
50.60782
1.00000
1.882997
40.76
0.5667
31.807
−41.311


23
21.07209
6.61768



27.724



24
−79.54129
1.00000
1.754998
52.32
0.5476
27.582
−47.508


25
66.22801
0.99806



26.863



26
48.90892
4.02300
1.882210
23.78
0.6036
26.802
40.333


27
−130.21404
1.94929



26.376



28
−37.12529
1.00000
1.618000
63.33
0.5441
26.194
−55.128


29
438.13751
0.20000



25.725



30
34.72260
1.88615
1.613397
44.30
0.5633
25.302
287.073


31
42.29949
(Variable)



24.769



32
−46.20252
1.00000
1.696797
55.53
0.5433
22.167
−45.199


33
101.17257
2.21450
1.808095
22.76
0.6307
23.128
112.579


34
−994.45522
(Variable)



23.547



35 (Stop)
∞
1.29695



28.883



36
143.50842
4.48049
1.816000
46.62
0.5568
29.930
47.136


37
−52.16988
0.20000



30.182



38
−52.13637
6.23615
1.487490
70.23
0.5300
29.349
48.593


39
−41.96851
1.20000
2.000690
25.46
0.6133
28.856
−39.407


40
781.32347
0.19891



28.725



41
22.82507
9.56381
1.516330
64.14
0.5352
28.572
29.895


42
−41.33452
1.00000
1.834000
37.16
0.5775
27.399
−26.832


43
50.02430
6.99907



25.923



44
386.69864
3.99920
1.487490
70.23
0.5300
25.416
67.610


45
−36.04126
1.08491



25.291



46
34.86509
4.96949
1.922860
20.88
0.6282
22.498
20.574


47
−39.79509
0.90000
1.882997
40.76
0.5667
21.517
−18.496


48
28.27246
8.88270



18.955



49
37.01797
4.62848
1.438750
94.93
0.5343
16.005
25.301


50
−15.30482
1.00000
1.953750
32.32
0.5898
15.736
−12.619


51
60.19086
2.75426



16.455



52
45.70173
3.00473
1.620411
60.23
0.5426
18.630
48.353


53
−86.09140
50.07000



18.983



Image plane
∞
















Aspherical surface data





First surface


K = 1.92497e+000 A4 = 1.92902e−009 A6 = 6.26259e−011 A8 = −9.53828e−014


A10 = 6.21216e−017 A12 = −2.17747e−020 A14 = 3.29927e−024 A16 = −2.10130e−028


Seventh surface


K = −2.29488e+001 A4 = −4.72874e−007 A6 = 4.95024e−011 A8 = 4.20753e−014


A10 = −7.75550e−017 A12 = 9.10273e−020 A14 = −5.11370e−023 A16 = 1.17437e−026


Twenty-second surface


K = 5.48442e−001 A4 = 1.59884e−007 A6 = −3.77659e−009 A8 = 1.79255e−011


A10 = − 4.48568e−014 A12 = −3.70888e−016 A14 = 2.09083e−018 A16 = −2.91328e−021





Various data


Zoom ratio 10.00













Wide angle
Intermediate
Telephoto






Focal length
18.00
63.00
180.00



F number
4.00
4.00
4.95



Half angle of
40.82
13.86
4.94



field






Image height
15.55
15.55
15.55



Total lens length
320.10
320.10
320.10



BF
50.07
50.07
50.07



d21
0.70
45.74
65.06



d31
60.47
8.62
6.48



d34
11.50
18.30
1.12















Entrance pupil position
57.50
105.61
175.05



Exit pupil position
−33.80
−33.80
−33.80



Front principal point position
71.63
121.28
−31.27



Rear principal point position
32.07
−12.93
−129.93










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point



Unit
surface
length
length
position
position






1
1
57.00
113.08
71.51
43.38



2
22
−26.70
18.67
3.98
−9.70



3
32
−76.10
3.21
−0.16
−1.98



4
35
31.05
62.40
−11.09
−41.97









Numerical Embodiment 2










Unit mm







Surface data














Surface





Effective
Focal


Number
r
d
nd
vd
θgF
diameter
length





 1*
86.96069
2.80000
1.772499
49.60
0.5521
99.506
−85.846


 2
37.19554
28.65314



72.568



 3
287.18991
2.20000
1.772499
49.60
0.5521
71.378
−151.018


 4
82.96532
9.79457



68.012



 5
233.30951
2.20000
1.772499
49.60
0.5521
67.303
−81.001


 6
49.32285
9.90654
1.922860
18.90
0.6495
64.827
83.114


 7
122.07948
4.11145



64.165



 8
174.57379
7.40358
1.496999
81.54
0.5374
63.832
170.294


 9*
−162.88781
10.55549



63.329



10
219.22560
11.10101
1.618000
63.33
0.5441
61.797
87.081


11
−70.29224
0.51997



61.501



12
−90.66362
2.00000
1.805181
25.42
0.6161
58.344
−51.316


13
77.98219
9.18481
1.496999
81.54
0.5374
56.765
117.857


14
−228.82556
0.21692



57.161



15
229.51464
10.00000
1.595220
67.74
0.5442
57.792
89.884


16
−68.94195
0.20000



57.805



17
57.54531
5.56934
1.730000
49.00
0.5575
50.901
114.868


18
174.06610
(Variable)



50.045



19*
222.99988
1.30000
1.772499
49.60
0.5521
29.397
−31.652


20
22.07423
8.73811



24.622



21
−46.00024
0.90000
1.772499
49.60
0.5521
21.288
−21.359


22
26.14240
4.04203
1.846660
23.78
0.6034
21.985
24.438


23
−96.70044
2.91044



22.088



24
−20.39226
0.90000
1.800999
34.97
0.5863
22.088
−89.160


25
−29.02640
(Variable)



23.053



26
−33.53567
0.90000
1.729157
54.68
0.5444
23.727
−29.601


27
62.00299
2.73134
1.846660
23.78
0.6205
25.908
73.336


28
5426.95120
(Variable)



26.494



29 (Stop)
∞
1.04258



27.557



30
144.60763
5.80564
1.834807
42.71
0.5642
29.049
38.100


31
−40.31316
0.20000



29.778



32
140.01330
2.90947
1.570989
50.80
0.5588
29.573
116.796


33
−127.51474
0.20000



29.431



34
62.82013
7.44444
1.496999
81.54
0.5374
28.583
43.611


35
−31.93064
1.20000
2.000690
25.46
0.6133
27.614
−30.706


36
1097.65571
0.20000



27.561



37
27.33320
3.43062
1.531717
48.84
0.5630
27.568
130.948


38
42.83669
17.98679



26.842



39
−77.25420
4.44564
1.487490
70.23
0.5300
23.060
306.323


40
−51.93660
20.78154



22.786



41
72.70183
7.72582
1.487490
70.23
0.5300
25.172
30.867


42
−18.39119
0.85000
1.953750
32.32
0.5898
25.094
−21.994


43
−145.10189
2.61020



27.091



44
837.85153
6.19253
2.102050
16.77
0.6721
29.071
32.378


45
−37.66305
0.85000
2.000690
25.46
0.6133
29.817
−28.178


46
136.96902
0.19086



30.863



47
42.04543
7.61002
1.487490
70.23
0.5300
32.756
52.334


48
−61.55333
33.54000



33.050



Image plane
∞
















Aspherical surface data





First surface


K = 1.16599e+000 A4 = 2.14949e−007 A6 = −3.885348−011 A8 = 1.50332e−014


Ninth surface


K = −9.49193e+000 A4 = 5.68085e−007 A6 = 2.51185e-010 A8 = 5.19688e−014


Nineteenth surface


K = −4.37435e+002 A4 = 1.00143e−005 A6 = −1.61464e−008 A8 = 2.99969e−011





Various data


Zoom ratio 5.00













Wide angle
Intermediate
Telephoto






Focal length
15.00
35.00
75.00



F number
3.00
3.00
3.00



Half angle of
46.03
23.96
11.71



field






Image height
15.55
15.55
15.55



Total lens length
300.20
300.20
300.20



BF
33.54
33.54
33.54



d18
0.99
21.34
32.89



d25
32.46
9.59
1.98



d28
2.70
5.23
1.28















Entrance pupil position
50.74
66.16
86.04



Exit pupil position
−158.40
−158.40
−158.40



Front principal point position
64.57
94.78
131.73



Rear principal point position
18.54
−1.46
−41.46










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point



Unit
surface
length
length
position
position






1
1
32.00
116.42
59.75
30.90



2
19
−18.80
18.79
3.92
−10.58



3
26
−50.00
3.63
−0.04
−2.03



4
29
40.41
91.68
23.49
−102.31









Numerical Embodiment 3










Unit mm







Surface data














Surface





Effective
Focal


Number
r
d
nd
vd
θgF
diameter
length





 1
1169.97001
3.20000
1.772499
49.60
0.5521
96.196
−86.637


 2
63.51741
23.65253



81.952



 3
−120.65898
2.70000
1.772499
49.60
0.5521
81.536
−153.974


 4
12736.29646
0.19644



83.190



 5
137.03668
5.93946
1.922860
20.88
0.6282
85.308
253.532


 6
318.82080
1.99862



84.987



 7
271.65559
14.52319
1.620411
60.29
0.5426
84.829
126.774


 8*
−109.03750
0.19636



84.334



 9
1217.78701
11.61409
1.496999
81.54
0.5374
78.550
168.129


10
−89.71276
2.50000
1.800000
29.84
0.6017
78.057
−155.348


11
−320.04558
7.41270



77.803



12
112.52390
2.50000
1.737999
32.26
0.5899
76.449
−159.641


13
57.21267
18.30702
1.496999
81.54
0.5374
73.743
97.085


14
−280.48528
0.20000



73.551



15
101.84132
9.22993
1.537150
74.81
0.5390
71.243
165.923


16
−709.19180
0.20000



70.430



17
83.33061
5.90316
1.790000
45.50
0.5720
64.795
195.921


18
173.80844
(Variable)



63.045



19*
61.54916
1.20000
1.882997
40.76
0.5667
29.211
−28.504


20
17.77319
5.41316



24.205



21
−159.39579
4.20515
1.846660
23.78
0.6034
24.051
32.622


22
−24.02808
0.70000
1.772499
49.60
0.5521
23.552
−36.395


23
−162.83076
2.58431



22.313



24
−23.84544
0.70000
1.729157
54.68
0.5444
22.322
−29.063


25
200.55833
0.16000



24.087



26
58.45160
4.05153
1.654115
39.70
0.5737
25.225
47.356


27
−64.90617
(Variable)



25.690



28
−33.60198
0.90000
1.651597
58.55
0.5426
26.193
−40.205


29
122.39841
2.45535
1.808095
22.76
0.6307
28.396
116.449


30
−422.01783
(Variable)



28.992



31 (Stop)
∞
1.29499



35.175



32
937.43324
4.48116
1.754988
52.32
0.5476
36.289
74.579


33
−60.07159
0.20000



36.843



34
68.90268
5.17787
1.618000
63.33
0.5441
38.045
80.550


35
−176.59285
0.20000



37.907



36
76.80512
5.15355
1.496999
81.54
0.5374
36.900
95.188


37
−121.35769
1.20000
2.001000
29.13
0.5997
36.351
−94.686


38
451.54241
0.19951



35.813



39
43.80046
10.46440
1.516330
64.14
0.5352
34.809
48.610


40
−54.46084
1.10000
1.772499
49.60
0.5521
32.722
−43.222


41
88.14685
23.84474



31.202



42
49.48699
4.85470
1.487490
70.23
0.5300
25.163
49.788


43
−46.40636
0.19996



25.061



44
28.21280
5.77563
1.487490
70.23
0.5300
23.317
34.245


45
−38.45968
1.00000
2.000690
25.46
0.6133
22.489
−15.479


46
26.68305
2.54412



21.327



47
271.15033
6.98468
1.808095
22.76
0.6307
21.567
19.111


48
−16.36352
1.00000
1.882997
40.76
0.5667
22.077
−17.554


49
339.47363
7.60841



23.513



50
35.22725
4.97126
1.487490
70.23
0.5300
29.657
67.719


51
−529.25312
37.90000



29.720



Image plane
∞
















Aspherical surface data





Eighth surface


K = 7.46975e−001 A4 = 1.99891e−007 A6 = 6.90199e−011 A8 = −1.88943e−013


A10 = 2.85379e−016 A12 = −2.31761e−019 A14 = 9.51659e−023 A16 = −1.55553e−026


Nineteenth surface


K = 5.13907e+000 A4 = 1.02312e−006 A6 = −1.14340e−008 A8 = 4.59324e−011


A10 = −3.79212e−013 A12 = 1.38269e−015 A14 = −1.51499e−018 A16 = −1.86650−021





Various data


Zoom ratio 8.00













Wide angle
Intermediate
Telephoto






Focal length
20.00
60.00
160.00



F number
2.80
2.80
3.60



Half angle of
37.87
14.53
5.55



field






Image height
15.55
15.55
15.55



Total lens length
310.03
310.03
310.03



BF
37.90
37.90
37.90



d18
0.69
30.37
44.35



d27
41.14
7.95
5.96



d30
9.40
12.91
0.93















Entrance pupil position
59.82
110.55
190.03



Exit pupil position
−86.03
−86.03
−86.03



Front principal point position
76.59
141.50
143.45



Rear principal point position
17.90
−22.10
−122.10










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point



Unit
surface
length
length
position
position






1
1
52.10
110.27
60.89
19.92



2
19
−21.50
19.01
2.12
−12.13



3
28
−62.00
3.36
−0.27
−2.18



4
31
37.40
88.25
8.75
−74.61









Numerical Embodiment 4










Unit mm







Surface data














Surface





Effective
Focal


Number
r
d
nd
vd
θgF
diameter
length





 1
133.81883
3.00000
1.772499
49.60
0.5521
90.057
−87.880


 2
44.73925
23.87215



72.971



 3
−167.36766
2.50000
1.772499
49.60
0.5521
72.606
−93.032


 4
127.84286
1.91426



72.647



 5
102.37636
7.51980
1.922860
20.88
0.6282
74.470
169.653


 6
279.42399
1.64636



74.063



 7*
150.90630
8.70581
1.620411
60.29
0.5426
74.022
160.132


 8
−207.65662
8.66215



73.699



 9
164.35762
9.37868
1.595220
67.74
0.5442
73.882
157.795


10
−216.26086
0.20000



73.584



11
134.40933
2.00000
1.882210
23.78
0.6036
69.914
−94.024


12
51.24522
16.88046
1.438750
94.93
0.5343
65.990
98.740


13
−256.15857
0.20000



66.035



14
86.69121
12.31733
1.770000
54.50
0.5550
65.245
73.671


15
−155.91296
(Variable)



64.209



16*
42.60200
1.20000
1.834807
42.71
0.5642
31.339
−35.032


17
17.17444
7.78247



25.592



18
−44.84220
0.80000
1.729157
54.68
0.5444
25.316
−33.000


19
52.81240
1.69099



24.142



20
40.60240
3.82252
1.846660
23.78
0.6034
23.802
36.560


21
−129.97366
2.63029



23.556



22
−24.87045
0.90000
1.834807
42.71
0.5642
23.531
−115.791


23
−33.97396
(Variable)



24.204



24
−27.10392
0.80000
1.639999
60.08
0.5370
24.578
−35.634


25
149.20046
2.54968
1.808095
22.76
0.6307
26.593
104.102


26
−195.97886
(Variable)



27.185



27 (Stop)
∞
1.71552



28.120



28
−466.88719
2.95712
1.772499
49.60
0.5521
29.050
97.620


29
−65.37333
0.20000



29.600



30
264.38094
4.09823
1.589130
61.14
0.5406
30.292
77.252


31
−54.91610
0.20000



30.505



32
72.98468
5.78813
1.516330
64.14
0.5352
30.050
52.941


33
−42.77332
1.20000
2.000690
25.46
0.6133
29.708
−44.919


34
−753.89691
0.91730



29.782



35
23.21503
3.28414
1.516330
64.14
0.5352
29.785
178.749


36
41.03538
23.25738



23.059



37
64.82994
0.90000
1.953750
32.32
0.5898
24.567
−36.795


38
22.72058
6.11702
1.808095
22.76
0.6307
24.367
22.735


39
−89.12908
1.72046



24.427



40
47.08069
5.42141
1.438750
94.93
0.5343
23.755
43.655


41
−31.28624
1.00000
1.805181
25.42
0.6161
23.307
−19.730


42
33.35913
10.29550



23.076



43
35.83585
7.33475
1.487490
70.23
0.5300
29.594
44.835


44
−52.71959
1.20000
1.834000
37.16
0.5775
29.689
−130.968


45
−102.35803
40.04000



30.020



Image plane
∞
















Aspherical surface data





Seventh surface


K = −1.31886e+001 A4 = −3.33339e−007 A6 = −1.00548e−011 A8 = 1.93377e−014


A10 = −5.83498e−017 A12 = 1.05163e−013 A14 = −7.28030e−023 A16 = 1.81611e−026


Sixteenth surface


K = −6.82246e+000 A4 = 1.53646e−005 A6 = −1.26474e−008 A8 = 3.57838e−011


A10 = −2.67322e−013 A12 = 2.11682e−015 A14 = −7.89376e−018 A16 = 1.19021e−020





Various data


Zoom ratio 5.00













Wide angle
Intermediate
Telephoto






Focal length
19.00
45.00
95.00



F number
2.70
2.70
2.70



Half angle of
39.30
19.06
9.30



field






Image height
15.55
15.55
15.55



Total lens length
277.64
277.64
277.64



BF
40.04
40.04
40.04



d15
0.70
22.76
34.43



d23
28.12
6.05
3.57



d26
10.20
10.21
1.02















Entrance pupil position
56.04
85.75
122.55



Exit pupil position
−103.97
−103.97
−103.97



Front principal point position
72.53
116.69
154.88



Rear principal point position
21.04
−4.96
−54.96










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point




surface
length
length
position
position






1
1
45.00
38.80
57.31
21.16



2
16
−24.80
18.83
2.46
−13.14



3
24
−55.00
3.35
−0.46
−2.37



4
27
40.26
77.61
19.72
−65.31









Numerical Embodiment 5










Unit mm







Surface data














Surface





Effective
Focal


Number
r
d
nd
vd
θgF
diameter
length





 1*
81.52156
2.80000
1.772499
49.60
0.5521
97.273
−83.251


 2
35.50574
31.30681



70.026



 3
667.71915
2.20000
1.772499
49.60
0.5521
68.022
−135.261


 4
90.59457
4.47839



64.610



 5
197.06072
2.20000
1.834807
42.71
0.5642
64.321
−66.614


 6
43.33682
11.33919
1.922860
18.90
0.6495
60.874
69.654


 7
113.32971
2.55719



59.842



 8
115.11681
9.51685
1.496999
81.54
0.5374
59.385
153.156


 9*
−220.41107
0.20000



58.068



10
185.45912
9.63439
1.618000
63.33
0.5441
57.517
91.373


11
−80.00592
2.00000
1.846660
23.78
0.6205
57.026
−103.318


12
−857.68120
5.60166



56.350



13
−547.42488
2.00000
1.846660
23.78
0.6205
55.107
−95.810


14
96.50030
8.54469
1.496999
81.54
0.5374
56.048
126.294


15
−175.74550
0.20000



56.723



16
248.42762
12.85098
1.595220
67.74
0.5442
58.081
80.834


17
−58.77230
0.20000



58.452



18
56.55329
6.43207
1.763850
48.51
0.5587
50.476
91.827


19
271.97337
(Variable)



49.270



20*
75.52289
1.30000
1.816000
46.62
0.5568
27.970
−25.770


21
16.38581
1.94998



22.551



22
−35.35061
0.90000
1.754998
52.32
0.5476
20.890
−28.150


23
54.49701
0.20000



20.318



24
38.34698
4.04203
1.846660
23.78
0.6034
20.314
27.246


25
−56.47379
2.18661



19.859



26
−20.15327
0.90000
1.882997
40.76
0.5667
19.635
−76.243


27
−29.29552
(Variable)



20.447



28
−28.24173
0.90000
1.729157
54.68
0.5444
21.748
−31.883


29
136.58830
2.26264
1.846660
23.78
0.6205
23.610
90.643


30
−177.80079
(Variable)



24.238



31 (Stop)
∞
1.80831



26.366



32
1876.46717
5.41221
1.816000
46.62
0.5568
27.823
37.988


33
−31.64154
0.20000



28.604



34
60.10061
8.24256
1.496999
81.54
0.5374
28.186
38.709


35
−27.12183
1.20000
2.001000
29.13
0.5997
27.594
−34.449


36
−126.12274
0.20000



28.202



37
27.44643
3.25073
1.612929
37.00
0.5862
28.528
139.096


38
38.53198
22.34855



27.776



39
−524.12330
5.21590
1.517417
52.43
0.5564
24.011
121.284


40
−56.46271
11.54753



24.632



41
111.79736
8.05123
1.496999
81.54
0.5374
24.704
33.474


42
−19.14232
0.85000
1.953750
32.31
0.5898
24.498
−25.679


43
−87.28015
3.16563



25.890



44
436.69471
5.32440
1.959060
17.47
0.6599
27.387
38.954


45
−41.20307
0.85000
2.001000
29.13
0.5997
27.768
−24.479


46
62.31899
0.38161



28.514



47
43.43683
7.60385
1.496999
81.54
0.5374
29.721
43.773


48
−41.28677
0.00000



30.288



Image plane
∞
41.02000















Aspherical surface data





First surface


K = 1.15930e+000 A4 = 3.25637e−007 A6 = −7.92964e−012 A8 = 8.93227e−015


Ninth surface


K = −4.96791e+001 A4 = 8.83515e−007 A6 = 5.16367e−010 A8 = 5.70862e−014


Twentieth surface


K = 8.19089e+000 A4 = 5.61681e−006 A6 = −9.29022e−009 A8 = 2.78530e−011





Various data


Zoom ratio 4.00













Wide angle
Intermediate
Telephoto






Focal length
14.00
28.00
56.00



F number
3.00
3.00
3.00



Half angle of
48.00
29.05
15.52



field






Image height
15.55
15.55
15.55



Total lens
297.27
297.27
297.27



length






BF
41.02
41.02
41.02



d19
1.00
17.72
28.94



d27
32.19
13.50
4.68



d30
2.70
4.67
2.27















Entrance pupil position
48.68
60.09
76.35



Exit pupil position
−122.20
−122.20
−122.20



Front principal point position
61.48
83.29
113.13



Rear principal point position
27.02
13.02
−14.98










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point



Unit
surface
Length
length
position
position






1
1
30.00
114.06
57.47
29.47



2
20
−19.00
17.48
2.47
−11.25



3
28
−50.00
3.16
−0.44
−2.20



4
31
37.44
85.65
20.00
−79.28









Numerical Embodiment 6










Unit mm







Surface data














Surface





Effective
Focal


number
r
d
nd
vd
θgF
diameter
length





 1
194.96209
3.00000
1.772499
49.60
0.5521
88.491
−88.490


 2
50.45050
23.69207



73.351



 3
−101.22704
2.50000
1.772499
48.60
0.5521
72.885
−111.690


 4
610.40944
0.19704



74.054



 5
112.46576
6.06429
1.922860
18.90
0.6495
75.732
194.404


 6
287.65098
4.86350



75.347



 7
−1837.00765
7.27013
1.651597
58.55
0.5426
75.086
230.062


 8
−139.33725
0.20000



74.929



 9
−472.70380
4.65675
1.595220
67.74
0.5442
72.970
424.413


10
−165.62101
8.66201



72.465



11
−192.35145
6.46656
1.537150
74.81
0.5390
66.913
268.083


12
−83.47137
0.99766



66.556



13
−78.26046
2.50000
1.800000
29.84
0.6017
66.067
−270.007


14
−123.92169
0.20000



67.015



15
144.80685
2.00000
1.846660
23.78
0.6034
66.705
−142.303


16
65.69817
13.00429
1.496999
81.54
0.5374
65.115
106.901


17
−263.45069
0.20000



65.049



18
131.23177
9.46925
1.496999
81.54
0.5374
64.015
146.867


19
−161.59164
0.20000



63.356



20
61.37933
6.25108
1.730000
49.00
0.5575
56.603
136.191


21
152.31744
(Variable)



55.097



22*
123.35380
1.20000
1.882997
40.76
0.5667
32.088
−28.857


23
21.12344
6.38054



26.928



24
−167.62168
4.33940
1.846660
23.78
0.6034
26.240
54.777


25
−37.04472
0.80000
1.772499
49.60
0.5521
25.538
−98.748


26
−72.37210
(Variable)



24.901



27
−25.91341
0.80000
1.834807
42.71
0.5642
24.536
−28.139


28
270.81861
0.16000



24.869



29
87.77809
3.31174
1.846660
23.78
0.6034
25.043
51.048


30
−85.31340
(Variable)



25.023



31
−31.89775
0.90000
1.686797
55.53
0.5433
25.027
−34.635


32
102.09398
2.46844
1.808095
22.76
0.6307
27.236
92.767


33
−290.19380
(Variable)



27.788



34 (Stop)
∞
1.28219



32.549



35
∞
5.00427
1.816000
46.62
0.5568
33.538
57.344


36
−47.02989
0.20000



34.253



37
121.66426
4.00000
1.589130
61.14
0.5406
34.746
118.312


38
−162.68134
0.20000



34.670



39
53.21128
7.67575
1.496999
81.54
0.5374
33.912
52.816


40
−49.60645
1.20000
1.846660
23.78
0.6205
33.197
−43.964


41
156.92657
0.19575



32.533



42
24.49279
7.89416
1.518229
58.90
0.5456
32.141
61.163


43
94.58401
1.10000
1.772499
49.60
0.5521
30.289
−78.875


44
36.97714
21.17659



28.740



45
55.51715
6.46969
1.805181
25.42
0.6161
22.663
21.616


46
−24.35459
0.90000
1.882997
40.76
0.5667
22.365
−19.627


47
62.39214
8.45794



22.051



48
118.59896
6.86089
1.438750
94.93
0.5343
23.601
34.489


49
−17.03788
1.00000
2.003300
28.27
0.5980
23.707
−26.491


50
−48.53765
7.21499



25.917



51
55.89004
6.66022
1.487490
70.23
0.5300
32.106
59.353


52
−58.04968
39.99000



32.395



Image plane
∞
















Aspherical surface data





Twenty-second surface


K = 3.15185e+001 A4 = 3.02637e−006 A6 = −5.86837e−009 A8 = −4.69891e−012





Movement locus data












B21 = 40.35954



B31 = 42.94793 B32 = 3.88703 B33 = −8.43442 B34 = 3.38458 B35 = 0.39726



B36 = 0.38969










Various data


Zoom ratio 6.50













Wide angle
Intermediate
Telephoto






Focal length
18.50
45.00
120.25



F number
2.80
2.80
3.43



Half angle of
40.05
19.06
7.37



field






Image height
15.55
15.55
15.55



Total lens length
300.07
300.07
300.07



BF
39.99
39.99
39.99



d21
0.68
25.34
41.04



d26
2.39
4.03
4.61



d30
39.84
10.82
3.22



d33
6.92
9.65
0.98















Entrance pupil position
54.12
84.17
136.89



Exit pupil position
−165.72
−165.72
−165.72



Front principal point position
70.96
119.33
186.85



Rear principal point position
21.49
−5.01
−80.26










Zoom lens unit data


















Front
Rear






Lens
principal
principal




First
Focal
structure
point
point



Unit
surface
length
length
position
position






1
1
46.00
102.40
59.41
25.26



2
22
−42.00
12.72
−2.77
−13.83



3
27
−67.00
4.27
−1.89
−4.39



4
31
−56.00
3.37
−0.33
−2.23



5
34
46.94
87.49
26.91
−102.68
















TABLE 1







values corresponding to conditional expressions in Numerical Examples 1 to 6














Numerical
Numerical
Numerical
Numerical
Numerical
Numerical



Example 1
Example 2
Example 3
Example 4
Example 5
Example 6


















Wide angle end
18.00
15.00
20.00
19.00
14.00
18.50



focal length fw









Telephoto end
180.00
75.00
160.00
95.00
56.00
120.25



focal length









Zoom
10.00
5.00
8.00
5.00
4.00
6.50



magnification









f1
57.00
32.00
52.10
45.00
30.00
46.00



f2
−26.70
−18.80
−21.50
−24.80
−19.00
−42.00



f3
−76.10
−50.00
−62.00
−55.00
50.00
−67.00



f4
31.05
40.41
37.40
40.26
37.44
−56.00



f5
—
—
—
—
—
46.94



f23
—
—
—
—
—
−22.82



f11
−56.03
−43.99
−67.42
−57.14
−39.10
−61.80



f12
143.79
170.29
134.47
160.13
124.97
150.18



f13
73.69
49.34
68.45
55.33
45.59
60.83



βnw
−1.96
−2.36
−2.01
−1.62
−2.22
−2.04


Conditional
f1/fw
3.17
2.13
2.61
2.37
2.14
2.49


expression (1)









Conditional
βnw
−1.96
−2.36
−2.01
−1.62
−2.22
−2.04


expression (2)









Conditional
f11/f1
−0.98
−1.37
−1.29
−1.27
−1.30
−1.34


expression (3)









Conditional
f13/f11
−1.32
−1.12
−1.02
−0.97
−1.17
−0.98


expression (4)









Conditional
f1/f2
−2.13
−1.70
−2.42
−1.81
−1.58
—


expression (5)









Conditional
f1/f23
—
—
—
—
—
−2.02


expression (6)









While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-234390, filed Nov. 12, 2013, which is hereby incorporated by reference herein in its entirety.

## Claims

1. A zoom lens, comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power that does not move for zooming;
a second lens unit having a negative refractive power that moves during zooming; and
an N-th lens unit having a positive refractive power that does not move for zooming, the N-th lens unit being arranged closest to the image side,
wherein the first lens unit comprises, in order from the object side to the image side:
a first sub-lens unit having a negative refractive power that does not move for focusing;
a second sub-lens unit having a positive refractive power that moves during focusing; and
a third sub-lens unit having a positive refractive power that does not move for focusing, and

wherein the following conditional expressions are satisfied:


1.5<f1/fw<3.5; and



−2.70<βnw<−1.45,



where f1 represents a focal length of the first lens unit, fw represents a focal length at a wide angle end of the zoom lens, and βnw represents a lateral magnification of the N-th lens unit at a wide angle end.

2. A zoom lens according to claim 1, wherein the following conditional expressions are satisfied:


−1.5<f11/f1<−0.9; and



−1.5<f13/f11<−0.9,


where f11 represents a focal length of the first sub-lens unit and f13 represents a focal length of the third sub-lens unit.

3. A zoom lens according to claim 1, wherein the following conditional expression is satisfied:


−3.0<f1/f2<−1.5,


where f2 represents a focal length of the second lens unit.

4. A zoom lens according to claim 1, further comprising a third lens unit disposed between the second lens unit and the N-th lens unit and having a negative refractive power that moves during zooming,
wherein the following conditional expression is satisfied:


−3.0<f1/f23<−1.5,



where f23 represents a combined focal length of the second lens unit and the third lens unit at a wide angle end.

5. A zoom lens according to claim 1,
wherein the second lens unit has at least one aspherical surface,
wherein, when the aspherical surface is applied to a surface having a positive refractive power, the surface has such a shape that the positive refractive power is increased toward a periphery from the optical axis, and
wherein, when the aspherical surface is applied to a surface having a negative refractive power, the surface has such a shape that the negative refractive power is decreased toward the periphery from the optical axis.

6. An image pickup apparatus, comprising:
a zoom lens comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power that does not move for zooming;
a second lens unit having a negative refractive power that moves during zooming; and
an N-th lens unit having a positive refractive power that does not move for zooming, the N-th lens unit being arranged closest to the image side,
wherein the first lens unit comprises, in order from the object side to the image side:
a first sub-lens unit having a negative refractive power that does not move for focusing;
a second sub-lens unit having a positive refractive power that moves along an optical axis during focusing; and
a third sub-lens unit having a positive refractive power that does not move for focusing, and

wherein the following conditional expressions are satisfied:


1.5<f1/fw<3.5; and



−2.70<βnw<−1.45,




where f1 represents a focal length of the first lens unit, fw represents a focal length at a wide angle end of the zoom lens, and βnw represents a lateral magnification at a wide angle end of the N-th lens unit when an axial ray enters from infinity in a state of focusing on the infinity; and
a solid-state image pickup element configured to receive an image formed by the zoom lens.