Zoom lens and image pickup apparatus including the same

Abstract

A zoom lens including, in order from an object side: a positive first lens unit not moving for zooming; a negative second lens unit moving during zooming; a negative third lens unit moving during zooming; and a fourth lens unit not moving for zooming and including an aperture stop, the fourth lens unit including first and second sub-lens units arranged on object side and image plane side of the aperture stop, respectively, in which a relationship between a maximum height of an axial ray from an optical axis in the first sub-lens unit when focusing at infinity at a wide angle end, and a maximum height of an axial ray at the aperture stop when focusing at infinity at the wide angle end and of full open aperture, and a lateral magnification of the fourth lens unit when focusing at infinity at the wide angle end are appropriately set.

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; 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 and includes an aperture stop, the fourth lens unit including a first sub-lens unit arranged on the object side of the aperture stop, and a second sub-lens unit arranged on an image plane side of the aperture stop, wherein the following conditions are satisfied:
1.1<h41/hap<2.0
3.0<4<1.8 where h41 represents a maximum height of an axial ray from an optical axis in the first sub-lens unit in a state in which focus is at infinity at a wide angle end, hap represents a maximum height of an axial ray from the optical axis at the aperture stop in a state of focusing on at infinity at the wide angle end and of full open aperture, and 4 represents a lateral magnification of the fourth lens unit in the state in which focus is at infinity at the wide angle end.

2. The zoom lens according to claim 1, wherein the following condition is satisfied:
3.00<fT/f4<30.00 where f4 represents a focal length of the fourth lens unit, and fT represents a focal length of the zoom lens at a telephoto end.

3. The zoom lens according to claim 1, wherein the following condition is satisfied:
1.50<fT/f1<10.00 where f1 represents a focal length of the first lens unit and fT represents a focal length of the zoom lens at a telephoto end.

4. The zoom lens according to claim 1, wherein the following condition is satisfied:
10.00<f1/f2<2.500 where f1 represents a focal length of the first lens unit and f2 represents a focal length of the second lens unit.

5. The zoom lens according to claim 1, wherein the first sub-lens unit includes at least one aspherical surface.

6. The zoom lens according to claim 1, wherein the zoom lens performs focusing with a lens unit disposed on the object side of the aperture stop.

7. The zoom lens according to claim 1, wherein the aperture stop does not move for zooming.

8. 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; 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 and includes an aperture stop, the fourth lens unit including a first sub-lens unit arranged on the object side of the aperture stop, and a second sub-lens unit arranged on an image plane side of the aperture stop, wherein the following conditions are satisfied:
1.1<h41/hap<2.0
3.0<4<1.8 where h41 represents a maximum height of an axial ray from an optical axis in the first sub-lens unit in a state in which focus is at infinity at a wide angle end, hap represents a maximum height of an axial ray from an optical axis at the aperture stop in a state of focusing on at infinity at the wide angle end and of full open aperture, and 4 represents a lateral magnification of the fourth lens unit in the state in which focus is at infinity at the wide angle end; and an image pickup element that photoelectrically converts an optical image formed by the zoom lens.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 1 (Numerical Embodiment 1) of the present invention.

(2) FIG. 2A is a longitudinal aberration diagram at an object distance of infinity at the wide angle end in Embodiment 1 (Numerical Embodiment 1).

(3) FIG. 2B is a longitudinal aberration diagram at the object distance of infinity at a focal length of 360.00 mm in Embodiment 1 (Numerical Embodiment 1).

(4) FIG. 2C is a longitudinal aberration diagram at the object distance of infinity at a telephoto end in Embodiment 1 (Numerical Embodiment 1).

(5) FIG. 3 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 2 (Numerical Embodiment 2) of the present invention.

(6) FIG. 4A is a longitudinal aberration diagram at an object distance of infinity at the wide angle end in Embodiment 2 (Numerical Embodiment 2).

(7) FIG. 4B is a longitudinal aberration diagram at the object distance of infinity at a focal length of 500.00 mm in Embodiment 2 (Numerical Embodiment 2).

(8) FIG. 4C is a longitudinal aberration diagram at the object distance of infinity at a telephoto end in Embodiment 2 (Numerical Embodiment 2).

(9) FIG. 5 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 3 (Numerical Embodiment 3) of the present invention.

(10) FIG. 6A is a longitudinal aberration diagram at an object distance of infinity at the wide angle end in Embodiment 3 (Numerical Embodiment 3).

(11) FIG. 6B is a longitudinal aberration diagram at the object distance of infinity at a focal length of 225.00 mm in Embodiment 3 (Numerical Embodiment 3).

(12) FIG. 6C is a longitudinal aberration diagram at the object distance of infinity at a telephoto end in Embodiment 3 (Numerical Embodiment 3).

(13) FIG. 7 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 4 (Numerical Embodiment 4) of the present invention.

(14) FIG. 8A is a longitudinal aberration diagram at an object distance of infinity at the wide angle end in Embodiment 4 (Numerical Embodiment 4).

(15) FIG. 8B is a longitudinal aberration diagram at the object distance of infinity at a focal length of 400.00 mm in Embodiment 4 (Numerical Embodiment 4).

(16) FIG. 8C is a longitudinal aberration diagram at the object distance of infinity at a telephoto end in Embodiment 4 (Numerical Embodiment 4).

(17) FIG. 9 is a schematic diagram of a main part, of an image pickup apparatus according to the present invention.

(18) FIG. 10A is a schematic diagram of a principle of the present invention.

(19) FIG. 10B is a schematic diagram of a structure in the related art.

DESCRIPTION OF THE EMBODIMENTS

(20) Hereinafter, features of a zoom lens according to the present invention are described with reference to the accompanying drawings.

(21) A zoom lens according to 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 for maintaining a position of an image plane fixed; and a fourth lens unit having a positive refractive power that does not move for zooming and includes an aperture stop.

Embodiment 1

(22) FIG. 1 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 1 of the present invention. A first lens unit U1 having a positive refractive power is configured not to move for zooming. A part of the first lens unit U1 is configured to move from an image side to an object side for focusing from the object at infinity to an object, at close distance. A second lens unit (variator lens unit) U2 having a negative refractive power for zooming is configured to move from the object side to the image side during zooming from the wide angle end (short focal length end) to a telephoto end (long focal length end). A third lens unit (compensator lens unit) U3 having a negative refractive power is configured to move in conjunction with the second lens unit U2 and correct an image plane variation accompanying zooming (move during zooming). A fourth lens unit (relay lens unit) U4 having a positive refractive power is configured not to move for zooming, and includes an aperture stop SP configured not to move for zooming. A first sub-lens unit U41 of the fourth lens unit is arranged on the object side of the aperture stop SP. A second, sub-lens unit U42 of the fourth lens unit is arranged on an image plane side of the aperture stop SP. A converter (extender) and the like for converting a focal length may be mounted in the second sub-lens unit U42. An image plane IP corresponds to an imaging plane of a solid image pickup element (photoelectric transducer). All of the above-mentioned lens unit-configurations are the same in Embodiments 2, 3, and 4, which are described later.

(23) Next, lens configurations of the lens units in Embodiment 1 are described. In the following, the lenses are arranged in order from the object side to the image side. The first lens unit U1 includes six lenses: a positive lens, a negative lens, a positive lens, a negative lens, a positive lens, and a negative lens. For focus adjustment (focusing), the two lenses on the image side: the positive lens and the negative lens are configured to move. The second lens unit 112 is constituted by one negative lens, a cemented lens of a negative lens and a positive lens, a negative lens, and a positive lens. The third lens unit U3 is constituted by a cemented lens of a negative lens and a positive lens. The first sub-lens unit U41 is constituted by two positive lenses. The second sub-lens unit U42 is constituted by the aperture stop SP, a cemented lens of a positive lens and a negative lens, a positive lens, a cemented lens of a negative lens and a positive lens, a positive lens, and two cemented lenses each including a negative lens and a positive lens.

(24) In general, in a case of a zoom lens including a first lens unit having a positive refractive power, which is configured not to move for zooming, a second lens unit having a negative refractive power, which is configured to move during zooming, and a third lens unit having a negative refractive power, a ray that exits the third lens unit is in a state of being diverged. Therefore, when an aperture stop is arranged right behind the third lens unit, an aperture of the stop is increased. In particular, in a case of a zoom lens having a large aperture and a high zoom ratio, an effect of increasing the aperture diameter becomes large. When the aperture diameter is increased, it becomes difficult to secure a space for storing a stop diaphragm of an aperture stop in a state of full open aperture (state in which the stop is fully open) and a lens barrel becomes thick, and hence it has been difficult to downsize the zoom lens. In the zoom lens according to the present invention, the fourth lens unit and the aperture stop for forming an image may be arranged appropriately to realize both an increase in zoom ratio and reductions in size and weight.

(25) A principle of the present invention is described with reference to FIG. 10A and FIG. 10B. A schematic configuration around the aperture stop SP of the zoom lens according to the present invention is illustrated in FIG. 10A. FIG. 10B is a schematic diagram for illustrating a configuration of a lens apparatus in the related art to describe advantages of the present invention. As illustrated in FIG. 10B, a ray in a state of being diverged exits the third lens unit U3, and hence in a case of the configuration in the related art in which the aperture stop is arranged right behind the third lens unit, the aperture diameter of the aperture stop is increased. On the other hand, in a case of the configuration according to the present invention in FIG. 10A, the ray that is in the state of being diverged and exits the third lens unit U3 is converted into a ray in a state of being converged in the first sub-lens unit U41. The aperture stop SP may be arranged for the converged ray to suppress the increase in aperture diameter and attain the increase in zoom ratio of the zoom lens.

(26) The zoom lens according to the present invention includes, in order from an object side to an image side, a first lens unit having a positive refractive power, which is configured not to move for zooming, a second lens unit having a negative refractive power, which is configured to move during zooming, a third lens unit having a negative refractive power, which is configured to move for maintaining a position of an image plane fixed, and a fourth lens unit having a positive refractive power, which is configured not to move for zooming and includes an aperture stop. The fourth lens unit includes a first sub-lens unit and a second sub-lens unit arranged on the object side and the image plane side of the aperture stop, respectively. The following conditional expressions are satisfied:
1.1<h41/hap<2.0(1)
3.0<4<1.8(2)
where h41 represents a maximum height of an axial ray from an optical axis in the first sub-lens unit (from a lens surface closest to the object side to a lens surface closest to the image side in the first sub-lens unit) in a state in which focus is at infinity at the wide angle end, hap represents a maximum ray height of an axial ray from the optical axis at the aperture stop in a state of focusing on at infinity at the wide angle end and of full open aperture, and 4 represents a lateral magnification of the fourth lens unit in the state in which focus is at infinity at the wide angle end.

(27) The conditional expression (1) defines a ratio of the maximum height of the ray in the first sub-lens unit U41 to the maximum height of the ray in the aperture stop SP in the state of full open aperture. The conditional expression (1) may be satisfied to satisfactorily correct aberration variations of the zoom lens and realize both the suppression of the increase in diameter of the aperture stop SP and the increase in zoom ratio.

(28) When the ratio exceeds the upper limit of the conditional expression (1), large refractive powers are required, for both of the first sub-lens unit U41 and the second sub-lens unit U42, which makes it difficult to correct the aberrations. When the ratio falls below the lower limit of the conditional expression (1), the effect of suppressing the aperture diameter is reduced to lead to an enlargement of the lens barrel. It is more preferred to set the conditional expression (1) as follows:
1.1<h41/hap<1.7(1a).

(29) The conditional expression (2) defines the lateral magnification of the fourth lens unit.

(30) The conditional expression (2) may be satisfied to suppress the total length of the zoom lens, satisfactorily correct the aberration variations of the zoom lens, and realize both the high zoom ratio and the reductions in size and weight. When the ratio exceeds the upper limit of the conditional expression (2), the lateral magnification of the fourth lens unit becomes small, with the result that the high zoom ratio cannot be attained. Moreover, when the high zoom ratio is to be maintained, the entire zoom length becomes long, which makes it difficult to attain the downsizing of the lens. When the ratio falls below the lower limit of the conditional expression (2), an enlargement ratio of the aberrations of the first to third lens units is increased, which makes it difficult to correct the aberrations. It is more preferred to set the conditional expression (2) as follows:
2.6<4<2.0(2a).

(31) The above-mentioned conditional expressions are satisfied in Numerical Embodiments of the present invention to realize, despite the zoom lens for a large format camera, the high zoom ratio and the reductions in size and weight by the effect of reducing the aperture stop, and attain the high optical performance over the entire zoom range from the wide angle end to the telephoto end.

(32) As another embodiment of the present invention, a ratio of a focal length of the zoom lens at the telephoto end to a focal length of the fourth lens unit is defined in the conditional expression (3):
3.00<fT/f4<30.00(3)

(33) The conditional, expression (3) is satisfied to satisfactorily correct the aberration variations of the zoom lens and realize both the high zoom ratio and the reductions in size and weight. When the ratio exceeds the upper limit of the conditional expression (3), the refractive power of the fourth lens unit becomes too large, which makes it difficult to correct the aberrations. When the ratio falls below the lower limit of the conditional expression (3), the refractive power of the fourth lens unit becomes too weak, which makes it difficult to reduce the total length of the zoom lens to be compact. It is more preferred to set the conditional expression (3) as follows:
8.00<fT/f4<20.00(3a).

(34) As another embodiment of the present invention, a ratio of the focal length of the zoom lens at the telephoto end to a focal length of the first lens unit is defined in the conditional expression (4):
1.50<fT/f1<10.00(4)

(35) The conditional expression (4) may be satisfied to suppress an axial chromatic aberration, which is problematic at the telephoto end, and a focus shift during zooming, which is caused by a manufacturing error and is problematic in a zoom lens that is usable in a telephoto range and has the high zoom ratio. When the ratio exceeds the upper limit of the conditional expression (4), the focal length of the first lens unit becomes relatively too short with respect to the focal length at the telephoto end, and an enlargement magnification of the first lens unit on a telephoto side becomes too large. In the case where the enlargement magnification of the first lens unit is large, the axial chromatic aberration generated in the first lens unit may no longer be corrected by the second and subsequent lens units, which makes it difficult to obtain high performance on the telephoto side. Further, a lateral magnification of the second lens unit becomes relatively large. In a case where various amounts of the second lens unit, here in particular a focal length, are shifted due to a manufacturing error of the second lens unit, the shift in focal length of the second lens unit also affects an image plane position. Now, when a lateral magnification of the second lens unit is represented by 2, a lateral magnification of the subsequent lens units is represented by c, and an amount of shift in image position on the second lens unit itself is represented by sk2, a variation in imaging position, which is generated in the second lens unit, is enlarged to an amount of focus shift sk on an image plane in the following expression:
sk=sk2(12.sup.2)c.sup.2(A).

(36) In regard to the expression (A), in the telephoto zoom lens having a high magnification as in the present invention, magnitudes of both 2 and c become larger than 1 at the telephoto end. Therefore, when the lateral magnification of the second lens unit becomes relatively large, the manufacturing error of the second lens unit has a larger effect on the image plane position, with the result that the focus shift due to the zooming becomes difficult to suppress, which affects manufacturability.

(37) When the ratio falls below the lower limit of the conditional expression (4), the focal length of the first lens unit becomes too large, which makes it difficult to downsize the first lens unit. It is more preferred to set the conditional expression (4) as follows:
2.50<fT/f1<6.30(4a).

(38) As another embodiment of the present invention, a ratio of the focal length of the first lens unit to a focal length of the second lens unit is defined in the conditional expression (5):
10.00<f1/f2<2.50(5).

(39) The conditional expression (5) is satisfied to reduce a movement amount of the second lens unit accompanying zooming while satisfactorily correcting the axial chromatic aberration, and reduce a total lens length while attaining the increase in magnification. When the ratio exceeds the upper limit of the conditional expression (5), the focal length of the second lens unit becomes relatively short, which is advantageous for the downsizing but increases the aberration variations accompanying zooming. When the ratio falls below the lower limit of the conditional expression (5), the focal length of the second lens unit becomes relatively long, and hence the movement amount of the second lens unit due to zooming is increased to increase the size of the zoom lens, which makes it difficult to reduce the size and weight. It is more preferred to set the conditional expression (5) as follows:
8.00<f1/f2<4.50(5a).

(40) As another embodiment of the present invention, it is desired that the first sub-lens unit U41 have at least one aspherical surface. At the wide angle end, an incident ray diverges the most when entering the first sub-lens unit U42, and hence the correction of spherical aberrations becomes the most important. The aspherical surface is arranged in the first sub-lens unit U41 having the large refractive power to advantageously correct the spherical aberrations.

(41) FIG. 2A, FIG. 2B, and FIG. 2C are longitudinal aberration diagrams at an object distance of infinity at the wide angle end, a focal length of 360.00 mm, and the telephoto end in Numeral Embodiment 1, respectively. Note, that, the value of the focal length is a value obtained when expressing Numerical Embodiment in units of mm, and the same applies to Numerical Embodiments. In aberration diagrams, the spherical aberration is illustrated with respect to an e-line and a g-line. An astigmatism is illustrated on a meridional image plane (M) with respect to the e-line and on a sagittal image plane (S) with respect to the e-line. A lateral chromatic aberration is expressed by the g-line. In all of the aberration diagrams, the spherical aberration, the astigmatism, the distortion, and the lateral chromatic aberration are drawn on scales of 0.5 mm, 0.5 mm, 5%, and 0.05 mm, respectively. Symbol Fno represents an F-number, and symbol represents a half angle of field. Note that, the wide angle end and the telephoto end refer to zoom positions when the second lens unit U2 configured to move during zooming is located at both ends of a range in which the second lens unit U2 is mechanically movable on the optical axis.

(42) The zoom lens in Numerical Embodiment 1 is a zoom lens having a zoom ratio of 18.0, a half angle of field at the wide angle end of 18.2 degrees, a half angle of field at the telephoto end of 1.1 degrees, and a maximum image height, which is determined by a product of the focal length and the half angle of field, of 14.8 mm.

(43) Numerical Embodiment 1 corresponding to Embodiment 1 is described in (Numerical Embodiment 1) below. In Numerical Embodiments, respectively, r represents a curvature radius of each surface counted from the object side, d represents an interval between surfaces, and nd and d represent a refractive index and an Abbe constant of each optical member. In this case, when 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, a paraxial curvature radius is represented by R, a conic constant is represented by k, and a spherical coefficients are represented by A4, A6, A8, A10, A12, A14, and A16, an aspherical surface shape is expressed by the following expression.

(44) $X=\frac{H^2/R}{1+\sqrt{1-\left(1+k\right){\left(H/R\right)}^2}}+A4H^4+A6H^6+A8H^8+A10H^{10}+A12H^{12}+A14H^{14}+A16H^{16}$
where e-Z means 10.sup.Z. The mark * represents the aspherical surface.

(45) In Table 1, corresponding values of the conditional expressions of Numerical Embodiment 1 are shown. Numerical Embodiment 1 satisfies all of the conditional expressions (1) to (5) to realize, despite the zoom lens for the large format camera, the high zoom ratio and the reductions in size and weight, and attain the high optical performance over the entire zoom range from the wide angle end to the telephoto end.

Embodiment 2

(46) FIG. 3 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 2.

(47) The zoom lens according to Embodiment 2 has the same lens configurations as those in Embodiment 1 for both of the first lens unit U1 and the third lens unit U3. The second lens unit U2 includes, in order from the object side to the image side, a negative lens, a cemented lens of a negative lens and a positive lens, and a negative lens. The first sub-lens unit U41 includes, in order from the object side to the image side, a positive lens, a positive lens, and a cemented lens of a positive lens and a negative lens. The second sub-lens unit U42 includes, in order from the object side to the image side, the aperture stop SP, a positive lens, one cemented lens of a negative lens and a positive lens, a negative lens, a cemented lens of a positive lens and a negative lens, and a positive lens.

(48) FIG. 4A, FIG. 4B, and FIG. 4C are longitudinal aberration diagrams at an object distance of infinity at the wide angle end, a focal length of 500.00 mm, and a telephoto end in Numerical Embodiment 2, respectively. Numerical Embodiment 2 is a zoom lens having a zoom ratio of 24.0, a half angle of field at the wide angle end of 16.5 degrees, a half angle of field at the telephoto end of 0.7 degree, and a maximum image height of 14.8 mm.

(49) Numerical Embodiment 2 corresponding to Embodiment 2 is described in (Numerical Embodiment 2) below. In Table 1, values corresponding to the conditional expressions in Numerical Embodiment 2 are shown. Numerical Embodiment 2 satisfies ail of the conditional expressions (1) to (5) to realize, despite the zoom lens for the large format camera, the high zoom ratio and the reductions in size and weight, and attain the high optical performance over the entire zoom range from the wide angle end to the telephoto end.

Embodiment 3

(50) FIG. 5 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 3.

(51) The zoom lens according to Embodiment 3 has the same lens configurations as those in Embodiment 1 for both of the second lens unit U2 and the third lens unit U3. The first lens unit U1 includes, in order from the object side to the image side, a cemented lens of a negative lens and a positive lens, a negative lens, and two positive lenses. The two positive lenses on the image plane side are configured to move for the focus adjustment. The first sub-lens unit U41 includes, in order from the object side to the image side, a positive lens, a cemented lens of a positive lens and a negative lens, and a positive lens. The second sub-lens unit U42 includes, in order from the object side to the image side, the aperture stop SP, a cemented lens of a negative lens and a positive lens, a cemented lens of a positive lens and a negative lens, a cemented lens of a negative lens and a positive tens, and a positive lens.

(52) FIG. 6A, FIG. 6B, and FIG. 6C are longitudinal aberration diagrams at an object distance of infinity at the wide angle end, a focal length of 225.00 mm, and a telephoto end in Numerical Embodiment 3, respectively. Numerical Embodiment 3 is a zoom lens having a zoom ratio of 10.0, a half angle of field at the wide angle end of 19.0 degrees, a half angle of field at the telephoto end of 2.0 degrees, and a maximum image height of 15.5 mm.

(53) Numerical Embodiment 3 corresponding to Embodiment 3 is described in (Numerical Embodiment 3) below. In Table 1, values corresponding to the conditional expressions in Numerical Embodiment 3 are shown. Numerical Embodiment 3 satisfies all of the conditional expressions (1) to (5) to realize, despite the zoom lens for the large format camera, the high zoom ratio and the reductions in size and weight, and attain the high optical performance over the entire zoom range from the wide angle end to the telephoto end.

Embodiment 4

(54) FIG. 7 is a lens cross-sectional view when focus is at an object at infinity at a wide angle end in a zoom lens according to Embodiment 4.

(55) The zoom lens according to Embodiment 4 has the same lens configurations as those in Embodiment 1 for all of the second lens unit U2, the third lens unit U3, and the fourth lens unit U4. The first lens unit U1 includes, in order from the object side to the image side, a positive lens configured not to move for the focus adjustment, a cemented lens of a positive lens and a negative lens, a positive lens and a cemented lens of a positive lens and a negative lens, which are configured to move for the focus adjustment, and a cemented lens of a positive lens and a negative lens configured not to move for the focus adjustment.

(56) FIG. 8A, FIG. 8B, and FIG. 8C are longitudinal aberration diagrams at an object distance of infinity at the wide angle end, a focal length of 400.00 mm, and a telephoto end in Numerical Embodiment 4, respectively. Numerical Embodiment 4 is a zoom lens having a zoom ratio of 19.4, a half angle of field at the wide angle end of 16.5 degrees, a half angle of field at the telephoto end of 0.9 degree, and a maximum image height of 14.8 mm.

(57) Numerical Embodiment 4 corresponding to Embodiment 4 is described in (Numerical Embodiment 4) below. In Table 1, values corresponding to the conditional expressions in Numerical Embodiment 4 are shown. Numerical Embodiment 4 satisfies all of the conditional expressions (1) to (5) to realize, despite the zoom lens for the large format camera, the high zoom ratio and the reductions in size and weight, and attain the high optical performance over the entire zoom range from the wide angle end to the telephoto end.

(58) (Image Pickup Apparatus)

(59) FIG. 9 is a schematic diagram of a main part of an image pickup apparatus (television camera system) using the zoom lens according to any one of Embodiments 1 to 4 of the present invention as an image pickup optical system. A zoom lens 101 that is the zoom lens according to any one of Embodiments 1 to 4 is illustrated in FIG. 9. The zoom lens 101 may be detachably mounted on a camera body 124, to thereby construct an image pickup apparatus 125. The zoom lens 101 includes a first lens unit F, a zoom portion LZ, and a fourth lens unit (FR, SP, RR) for imagine. The first lens unit F includes a lens unit for focusing.

(60) The zoom portion LZ includes a second lens unit configured to move on the optical axis during zooming, and a third lens unit configured to move on the optical axis to correct the image plane variation accompanying zooming. The zoom lens 101 further includes a first sub-lens unit FR configured not to move for zooming, an aperture stop SP, and a second sub-lens unit RR. The fourth lens unit (FR, SP, RR) includes lens units IE and IE that may be retractably inserted in an optical path. The lens units IE and IE are switched to displace a focal length range of the zoom lens 101. Drive mechanisms 114 and 115, such as a helicoid and a cam, drive the first lens unit F and the zoom portion LZ in an optical axis direction, respectively. Motors (drive units) 116 to 118 electrically drive the drive mechanisms 114 and 115 and the aperture stop SP.

(61) Detectors 119 to 121, such as an encoder, a potentiometer, or a photo-sensor, are configured to detect positions of the first lens unit F and the zoom portion LZ on the optical axis, and an aperture diameter of the aperture stop SP. The camera 124 includes a glass block 109, which corresponds to an optical filter or a color separation optical system provided within the camera 124. Further, the camera 124 includes an image pickup element (photoelectric transducer) 110, such as a charge-coupled device (CCD) sensor or a complementary metal-oxide semiconductor (CMOS) sensor. The image pickup element 110 is configured to photoelectrically convert a subject image (optical image) formed by the zoom lens 101. Further, central processing units (CPUs) 111 and 122 control the driving of the camera 124 and the zoom lens 101.

(62) By applying the zoom lens according to the present invention to a television camera as described above, the image pickup apparatus having the high optical performance may be realized.

(63) The exemplary embodiments of the present invention are described above, but the present invention is not limited to those embodiments and can be modified and changed variously within the scope of the gist thereof.

Numerical Embodiment 1

(64) TABLE-US-00001 Unit mm Surface data Surface Effective number r d nd d diameter 1 171.566 17.30 1.48749 70.2 127.99 2 2020.966 1.00 126.24 3 160.873 3.40 1.72916 54.7 116.87 4 103.410 5.64 111.47 5 116.704 22.15 1.43387 95.1 110.98 6 335.843 1.50 109.47 7 267.352 3.20 1.72916 54.7 109.18 8 214.311 15.52 105.48 9 151.203 17.14 1.43387 95.1 104.61 10 319.974 0.20 103.71 11 137.411 6.49 1.43387 95.1 96.73 12 204.597 (Variable) 94.79 13* 16816.966 1.20 1.77250 49.6 33.29 14 29.929 7.11 29.98 15 104.154 1.00 1.61800 63.3 29.37 16 30.718 7.91 1.72047 34.7 28.98 17 67.474 3.62 28.62 18 34.029 1.00 1.61800 63.3 27.30 19 450.776 0.20 27.36 20 93.693 2.63 1.54814 45.8 27.42 21 6580.233 (Variable) 27.54 22 68.940 1.00 1.72916 54.7 37.31 23 166.734 3.39 1.84666 23.8 38.97 24 941.897 (Variable) 39.61 25 109.548 6.39 1.59349 67.0 41.38 26* 84.491 1.00 41.75 27 47.765 9.81 1.61800 63.3 42.20 28 118.118 6.92 41.16 29 (Stop) 2.00 33.82 30 647.610 6.06 1.43875 94.9 31.97 31 36.685 1.20 2.00330 28.3 30.50 32 776.497 4.99 29.98 33 97.392 7.65 1.56732 42.8 28.86 34 43.937 3.12 27.88 35 89.504 1.20 2.00100 29.1 23.97 36 17.948 7.35 1.84666 23.8 22.49 37 104.985 50.00 21.92 38 46.809 7.83 1.48749 70.2 29.16 39 43.713 3.00 28.97 40 88.859 1.00 1.83431 42.7 26.91 41 46.519 6.34 1.72825 28.5 26.50 42 96.270 2.84 26.25 43 31.300 1.00 1.88300 40.8 25.94 44 100.302 4.54 1.64769 33.8 26.68 45 48.713 (BF) 27.55 Image plane Aspherical surface data Thirteenth surface K = 9.73498e+005 A4 = 2.31247e006 A6 = 4.19291e010 A8 = 5.17688e012 A10 = 6.87050e014 A12 = 8.08198e016 A14 = 2.95438e018 A16 = 3.78802e021 Twenty-sixth surface K = 1.02447e+000 A4 = 8.56896e007 A6 = 4.82804e010 A8 = 1.11536e012 A10 = 3.74032e015 A12 = 2.44824e018 A14 = 5.57191e021 A16 = 7.94532e024 Various data Zoom ratio 18.00 Wide angle Intermediate Telephoto Focal length 45.00 360.00 810.00 F-number 4.50 4.50 6.83 Half angle of field 18.21 2.35 1.05 Image height 14.80 14.80 14.80 Total lens length 458.75 458.75 458.75 BF 55.00 55.00 55.00 d12 10.00 116.76 133.26 d21 135.90 9.26 10.50 d24 1.00 20.87 3.14 Incident pupil position 166.49 1185.81 2300.95 Exit pupil position 128.10 128.10 128.10 Front principal point position 200.43 838.00 472.33 Rear principal point position 10.00 305.00 755.00 Zoom lens unit data Front Rear Lens principal principal First Focal structure point point Unit surface length length position position 1 1 216.70 93.54 36.17 42.41 2 13 30.00 24.67 3.39 14.40 3 22 111.70 4.39 0.29 2.70 4 25 57.66 134.26 7.85 142.30 Single lens data Lens First surface Focal length 1 1 324.14 2 3 405.46 3 5 202.12 4 7 161.98 5 9 238.70 6 11 934.65 7 13 38.49 8 15 38.13 9 16 30.12 10 18 50.97 11 20 167.68 12 22 66.48 13 23 165.91 14 25 81.08 15 27 56.10 16 30 79.15 17 31 34.60 18 33 54.14 19 35 14.73 20 36 24.37 21 38 47.56 22 40 36.25 23 41 43.53 24 43 51.58 25 44 140.34

Numerical Embodiment 2

(65) TABLE-US-00002 Unit mm Surface data Surface Effective number r d nd d diameter 1 163.528 17.53 1.49700 81.5 121.93 2 673.882 1.00 120.52 3 135.037 3.70 1.77250 49.6 111.44 4 100.355 4.59 106.76 5 108.786 16.31 1.43387 95.1 106.00 6 2381.643 4.35 104.44 7 382.047 3.20 1.77250 49.6 104.30 8 183.501 13.20 100.76 9 157.156 10.86 1.49700 81.5 100.53 10 12135.290 0.20 99.95 11 252.223 7.96 1.49700 81.5 98.13 12 1829.629 (Variable) 97.21 13* 476.807 1.20 1.72916 54.7 38.72 14 33.366 4.08 34.75 15 163.349 1.00 1.61800 63.3 34.72 16 25.003 10.15 1.72047 34.7 33.07 17 142.539 5.31 32.04 18 34.777 1.00 1.69680 55.5 29.67 19 269.964 (Variable) 29.60 20 70.407 1.00 1.72916 54.7 31.24 21 141.360 2.95 1.34666 23.8 32.35 22 5387.417 (Variable) 32.88 23 608.617 3.68 1.51633 64.1 49.35 24* 214.177 0.20 49.94 25 61.906 11.98 1.49700 81.5 52.67 26 86.144 0.50 52.52 27 92.723 10.45 1.43875 94.9 48.89 28 69.566 1.50 2.00100 29.1 47.43 29 159.602 5.06 46.55 30 (Stop) 2.00 46.74 31 61.251 8.19 1.68893 31.1 47.11 32 183.670 19.21 46.51 33 64.343 1.20 2.00100 29.1 32.74 34 41.407 7.29 1.76182 26.5 32.31 35 66.209 53.12 32.39 36 50.541 1.50 2.00100 29.1 20.34 37 152.778 8.68 20.79 38 87.153 5.68 1.76182 26.5 23.58 39 25.761 1.00 2.00100 29.1 23.65 40 107.046 1.42 24.36 41 64.341 4.19 1.67270 32.1 25.50 42 91.204 (BF) 25.82 Image plane Aspherical surface data Thirteenth surface K = 0.00000e+000 A4 = 3.52166e006 A6 = 9.04430e010 A8 = 4.01975e014 A10 = 2.11683e015 A12 = 4.10839e019 Twenty-fourth surface K = 8.40684e001 A4 = 5.82961e007 A6 = 1.12421e010 A8 = 2.39096e013 A10 = 2.88892e016 A12 = 2.42509e019 Various data Zoom ratio 24.00 Wide angle Intermediate Telephoto Focal length 50.00 500.00 1200.00 F-number 4.50 4.49 10.00 Half angle of field 16.49 1.70 0.71 Image height 14.80 14.80 14.80 Total lens length 465.00 465.00 465.00 BF 55.00 55.00 55.00 d12 6.31 109.89 122.42 d19 114.62 3.35 26.63 d22 32.62 40.31 2.50 Incident pupil position 168.58 1476.41 3303.63 Exit pupil position 101.85 101.85 101.85 Front principal point position 202.64 382.51 4677.24 Rear principal point position 5.00 445.00 1145.00 Zoom lens unit data Front Rear Lens principal principal First Focal structure point point Unit surface length length position position 1 1 208.00 82.90 24.79 44.72 2 13 33.00 22.74 6.49 8.60 3 20 106.77 3.95 0.09 2.26 4 23 57.71 146.86 15.60 128.59 Single lens data Lens First surface Focal length 1 1 265.86 2 3 528.01 3 5 261.51 4 7 159.31 5 9 311.35 6 11 445.27 7 13 42.54 8 15 47.72 9 16 30.09 10 18 57.15 11 20 64.05 12 21 161.14 13 23 306.16 14 25 74.26 15 27 92.18 16 28 47.85 17 31 67.09 18 33 24.82 19 34 34.15 20 36 75.40 21 38 26.45 22 39 20.50 23 41 56.29

Numerical Embodiment 3

(66) TABLE-US-00003 Unit mm Surface data Surface Effective number r d nd d diameter 1 157.510 3.24 1.77250 49.6 94.21 2 95.072 19.46 1.43387 95.1 90.72 3 191.109 1.00 89.88 4 166.514 2.59 1.77250 49.6 89.74 5 710.449 18.15 88.81 6 176.125 10.10 1.49700 81.5 83.31 7 264.901 0.12 82.83 8 131.655 5.69 1.43387 95.1 77.60 9 231.485 (Variable) 75.86 10* 187.641 1.20 1.75500 52.3 38.10 11 29.330 7.31 34.12 12 89.656 1.20 1.59522 67.7 34.08 13 42.559 6.16 1.72047 34.7 34.15 14 149.500 2.87 34.07 15 43.838 1.20 1.59522 67.7 33.95 16 112.394 0.20 34.87 17 71.657 4.37 1.61340 44.3 35.34 18 190.404 (Variable) 35.43 19 74.782 1.20 1.81600 46.6 36.00 20 143.656 3.50 1.84666 23.8 37.59 21 433.333 (Variable) 38.19 22 159.347 5.57 1.72916 54.7 40.00 23* 80.436 0.15 40.37 24 38.413 9.36 1.49700 81.5 40.44 25 136.507 1.20 2.00330 28.3 39.59 26 160.444 0.20 38.79 27 39.891 7.60 1.61800 63.3 38.11 28 325.501 12.60 36.98 29 (Stop) 1.97 24.20 30 385.088 0.90 1.88300 40.8 22.45 31 19.984 8.25 1.43875 94.9 20.69 32 29.856 1.50 19.87 33 25.114 4.24 1.65412 39.7 18.91 34 14.890 0.90 1.77250 49.6 18.77 35 98.116 2.38 19.00 36 66.091 0.80 1.81600 46.6 18.90 37 61.343 4.37 1.72047 34.7 19.64 38 34.826 30.44 20.39 39 249.121 2.56 1.61340 44.3 26.38 40 96.914 (BF) 26.70 Image plane Aspherical surface data Tenth surface K = 2.66952e+001 A4 = 1.14636e008 A6 = 6.88265e010 A8 = 5.30064e013 A10 = 2.68365e015 A12 = 3.77686e018 Twenty-third surface K = 1.35273e+000 A4 = 4.87432e007 A6 = 6.89220e011 A8 = 8.71132e013 A10 = 1.68652e015 A12 = 1.79632e018 Various data Zoom ratio 10.00 Wide angle Intermediate Telephoto Focal length 45.00 225.00 450.00 F-number 4.00 4.00 5.44 Half angle of field 19.01 3.94 1.97 Image height 15.50 15.50 15.50 Total lens length 345.16 345.16 345.16 BF 50.54 50.54 50.54 d9 2.58 84.86 102.53 d18 105.87 9.62 5.63 d21 1.62 15.59 1.90 Incident pupil position 102.73 562.96 1088.73 Exit pupil position 67.31 67.31 67.31 Front principal point position 130.55 358.38 179.55 Rear principal point position 5.54 174.46 399.46 Zoom lens unit data Front Rear Lens principal principal First Focal structure point point Unit surface length length position position 1 1 165.00 60.36 34.98 13.68 2 10 35.00 24.52 2.61 15.92 3 19 115.00 4.70 0.60 3.16 4 22 48.04 94.98 2.27 99.60 Single lens data Lens First surface Focal length 1 1 316.15 2 2 149.04 3 4 280.78 4 6 213.86 5 8 689.93 6 10 45.99 7 12 48.15 8 13 46.29 9 15 52.65 10 17 84.96 11 19 59.82 12 20 126.53 13 22 73.71 14 24 61.23 15 25 72.76 16 27 57.75 17 30 21.37 18 31 28.67 19 33 47.73 20 34 22.72 21 36 38.84 22 37 31.31 23 39 255.57

Numerical Embodiment 4

(67) TABLE-US-00004 Unit mm Surface data Surface Effective number r d nd d diameter 1 424.595 11.09 1.48749 70.2 126.35 2 594.285 0.20 125.51 3 173.957 19.89 1.43875 94.9 118.14 4 291.286 4.00 1.72047 34.7 116.31 5 807.691 16.85 113.22 6 442.688 8.68 1.43387 95.1 108.28 7 791.619 0.20 106.50 8 178.245 10.17 1.43875 94.9 101.53 9 6078.912 2.50 1.74950 35.3 99.95 10 701.579 3.00 98.21 11 1195.134 10.09 1.85478 24.8 96.69 12 211.097 2.20 1.74950 35.3 95.28 13 287.381 (Variable) 90.30 14* 650.746 1.20 1.77250 49.6 34.49 15 29.914 5.46 31.13 16 1357.488 1.00 1.59522 67.7 30.87 17 31.724 6.97 1.72047 34.7 30.14 18 245.341 3.24 29.56 19 35.831 1.00 1.59522 67.7 29.30 20 189.754 0.20 29.59 21 95.865 2.86 1.72047 34.7 29.74 22 558.084 (Variable) 29.71 23 70.636 1.00 1.72916 54.7 35.49 24 124.130 2.96 1.85478 24.8 37.03 25 4972.820 (Variable) 37.47 26 133.386 6.41 1.60311 60.6 42.87 27* 82.961 1.00 43.27 28 44.374 10.82 1.48749 70.2 43.66 29 115.328 5.00 42.62 30 (Stop) 2.00 37.50 31 73.236 7.38 1.43875 94.9 34.52 32 46.594 1.20 1.88300 40.8 33.02 33 75.284 13.46 31.40 34 47.133 6.57 1.58913 61.1 29.35 35 88.341 1.00 28.33 36 177.549 1.20 1.95375 32.3 26.28 37 18.943 4.80 1.64769 33.8 24.00 33 49.212 35.00 23.70 39 87.063 4.31 1.51633 64.1 29.91 40 110.328 15.29 29.91 41 67.625 1.00 1.88300 40.8 27.71 42 28.224 9.58 1.72825 28.5 28.46 43 31.135 4.91 28.98 44 21.870 1.00 1.95375 32.3 27.67 45 87.522 8.06 1.51742 52.4 30.38 46 21.424 (BF) 31.88 Image plane Aspherical surface data Fourteenth surface K = 2.35314e+002 A4 = 1.93318e006 A6 = 4.20833e010 A8 = 1.72913e011 A10 = 1.51882e013 A12 = 7.31823e016 A14 = 1.83686e018 A16 = 1.86030e021 Twenty-seventh surface K = 2.08328e+000 A4 = 4.85459e007 A6 = 1.21437e010 A8 = 1.41513e013 A10 = 5.06031e017 A12 = 2.55554e019 A14 = 5.54086e022 A16 = 1.16997e024 Various data Zoom ratio 19.40 Wide angle Intermediate Telephoto Focal length 50.00 400.00 970.00 F-number 4.50 4.50 8.00 Half angle of field 16.49 2.12 0.87 Image height 14.80 14.80 14.80 Total lens length 453.00 453.00 453.00 BF 55.00 55.00 55.00 d13 4.00 111.70 129.65 d22 130.93 5.52 12.60 d25 8.32 26.02 1.00 Incident pupil position 161.92 1248.43 2562.17 Exit pupil position 170.62 170.62 170.62 Front principal point position 200.84 939.26 638.17 Rear principal point position 5.00 345.00 915.00 Zoom lens unit data Front Rear Lens principal principal First Focal structure point point Unit surface length length position position 1 1 230.00 88.86 4.21 58.90 2 14 32.50 21.93 3.40 12.18 3 23 109.50 3.96 0.11 2.27 4 26 68.70 140.00 18.78 175.06 Single lens data Lens First surface Focal length 1 1 508.12 2 3 250.89 3 4 294.68 4 6 654.14 5 8 417.26 6 9 1051.34 7 11 208.61 8 12 160.99 9 14 40.43 10 16 51.88 11 17 39.14 12 19 50.38 13 21 112.99 14 23 61.34 15 24 140.39 16 26 85.43 17 28 67.00 18 31 65.98 19 32 32.26 20 34 52.92 21 36 22.15 22 37 44.44 23 39 94.60 24 41 22.31 25 42 21.64 26 44 30.58 27 45 52.40

(68) TABLE-US-00005 TABLE 1 Values corresponding to the conditional expressions in Numerical Embodiments 1 to 4 Conditional Numerical Embodiment Expression 1 2 3 4 fT 810 1,200 450 970 f1 216.7 208 165 230 f2 30.0 33.0 35.0 32.5 f4 57.7 57.7 48.0 68.7 h41 4.09 4.46 3.54 3.84 hap 3.31 4.01 2.04 3.27 (1) h41/hap 1.24 1.11 1.73 1.17 (2) 4 2.42 2.18 2.13 2.35 (3) fT/f4 14.05 20.79 9.37 13.83 (4) fT/f1 3.74 5.77 2.73 4.13 (5) f1/f2 7.22 6.30 4.71 7.08

(69) 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.

(70) This application claims the benefit of Japanese Patent Application No. 2014-122527, filed Jun. 13, 2014, which is hereby incorporated by reference herein in its entirety.