JP2016080973A - Zoom lens and imaging apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small zoom lens readily performing quick focusing and capable of obtaining high optical performance over an entire zoom range and a whole object distance at a high zoom ratio.SOLUTION: A zoom lens comprises, in order from an object side to an image side: first to third lens groups having positive, negative, and positive refractive power; a rear group including two or more lens groups; and an aperture diaphragm between the second and third lens groups. The third lens group is composed of a first partial group and a second partial group. At least the first partial group moves on an optical axis during focusing. The zoom lens individually and appropriately sets: an i-th lens group representing a lens group of the i-th (i=1-n) counted from the object side; a lateral magnification βiT of the i-th lens group at a telephoto end during focusing at an infinite distance; a lateral magnification βiW of the i-th lens group at a wide angle end during focusing at an infinite distance; and a composite zooming ratio ZR of the lens group positioned closer to the image side than the second lens group.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same. For example, an image pickup apparatus using a solid-state image pickup device such as a video camera, an electronic still camera, a broadcast camera, a surveillance camera, or a camera using a silver salt film. It is suitable for an imaging device.

  In recent years, an imaging optical system used in an imaging apparatus is required to be a high-performance zoom lens with a high zoom ratio while the entire system is small. Further, these zoom lenses are required to be able to focus at high speed and with high accuracy. Conventionally, there is known a positive lead type zoom lens using an inner focus type in which the entire system is small and has a high zoom ratio, and focusing is performed using a small and light lens group closer to the image side than the first lens group closest to the object side. (Patent Documents 1 to 4).

  In general, an inner focus type zoom lens that performs focusing using a lens group other than the first lens group has a smaller effective diameter of the first lens group than a zoom lens that moves the first lens group to perform focusing. Overall size reduction is facilitated. Further, close-up photography, particularly close-up photography is facilitated. Further, since the small and light lens group is moved, the driving force of the lens group is small, and quick focusing is possible.

  Patent Document 1 includes first to fifth lens groups having positive, negative, positive, negative, and positive refractive power in order from the object side to the image side, and performs zooming by changing the interval between adjacent lens groups. A zoom lens in which focusing is performed by a part of the second lens group is disclosed. Patent Document 2 includes first to fifth lens units having positive, negative, positive, positive, and negative refractive powers in order from the object side to the image side, and performs zooming by changing the interval between adjacent lens units. A zoom lens in which focusing is performed by a third lens group is disclosed.

  Patent Document 3 is composed of first to fifth lens groups having positive, negative, positive, negative, and positive refractive power in order from the object side to the image side, and performs zooming by changing the interval between adjacent lens groups. A zoom lens in which focusing is performed by a third lens group is disclosed. In Patent Document 4, zooming is performed by changing the interval between adjacent lens units including first to fifth lens units having positive, negative, positive, positive, and negative refractive powers in order from the object side to the image side. A zoom lens in which focusing is performed with five lens groups is disclosed.

JP 2012-159746 A JP 1997-090226 A JP 2009-251114 A JP 2011-090190 A

  In a zoom lens, in order to obtain high optical performance over the entire zoom range and the entire object distance while securing a predetermined zoom ratio, it is important to appropriately set each element constituting the zoom lens. For example, the zoom type (number of lens groups and the refractive power of each lens group), the movement trajectory associated with zooming of each lens group, the magnification burden of each lens group, the selection of the lens group for focusing and the lens configuration, etc. Setting is important.

  If these configurations are not appropriate, the entire system becomes larger when a high zoom ratio is achieved, and fluctuations in various aberrations associated with zooming and focusing increase, resulting in high optical performance over the entire zoom range and overall object distance. It becomes very difficult to get. For example, in the positive lead type zoom lens disclosed in Patent Documents 1 to 4, a high zoom ratio is achieved by giving a large zoom ratio to the second lens group which is the main zoom lens group. However, if the second lens group has a large zoom ratio, it is necessary to increase the interval change during zooming between the first lens group and the second lens group, which tends to increase the size of the entire lens system.

  For quick focusing, the focus lens is small and the focusing magnification of the focus lens and the lens group located on the image side of the focus lens is set appropriately so that the amount of focusing movement is small. There is a need to. In particular, in order to achieve a high zoom ratio and quick focusing, it is important to appropriately set the imaging magnification of each lens group and the change in imaging magnification accompanying zooming.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small zoom lens and an image pickup apparatus having the same that can easily focus quickly, have a high zoom ratio, and can obtain high optical performance over the entire zoom range and the entire object distance.

The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and two or more lenses. A zoom lens having a rear group including a group, wherein an interval between adjacent lens groups is changed during zooming, and has an aperture stop between the second lens group and the third lens group, and the third lens The group includes a first partial group having a positive refractive power and a second partial group having a positive or negative refractive power. At the time of focusing, at least the first partial group moves on the optical axis and is counted from the object side. The i-th (i = 1 to n) lens group is the i-th lens group, and the lateral magnification of the i-th lens group at the telephoto end when focusing to infinity is βiT, and the infinite distance is focused. ΒiW is the lateral magnification of the i-th lens group at the wide-angle end when ZR = (β3T × β4T ×... ΒβT) / (β3W × β4W ×... ΒnW)
And when
3.00 <ZR <10.00
−2.50 <β2T <−0.90
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a small zoom lens that is easy to quickly focus and has a high zoom ratio and high optical performance over the entire zoom range and the entire object distance.

Cross-sectional view of a lens according to Example 1 of the present invention (A), (B), (C) Longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end and the intermediate zoom position and at the telephoto end in Example 1 (A), (B), (C) Longitudinal aberration diagrams when focusing on a finite distance (700 mm from the image plane) at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 1 Lens sectional drawing of Example 2 of the present invention (A), (B), (C) Longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end and the intermediate zoom position and at the telephoto end in Example 2 (A), (B), (C) Longitudinal aberration diagrams when focusing on a finite distance (700 mm from the image plane) at the wide-angle end and the intermediate zoom position and the telephoto end of Example 2 Lens sectional view of Example 3 of the present invention (A), (B), (C) Longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end and the intermediate zoom position and at the telephoto end in Example 3 (A), (B), (C) Longitudinal aberration diagrams when focusing on a finite distance (700 mm from the image plane) at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 3 Lens sectional view of Example 4 of the present invention (A), (B), (C) Longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end and the intermediate zoom position and at the telephoto end in Example 4 (A), (B), (C) Longitudinal aberration diagrams when focusing on a finite distance (700 mm from the image plane) at the wide-angle end, the intermediate zoom position, and the telephoto end of Example 4 Schematic diagram of main parts of an imaging apparatus of the present invention

  Embodiments of the zoom lens of the present invention and an image pickup apparatus having the same will be described below. The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and two or more lenses. There is a rear group including a group, and the interval between adjacent lens groups changes during zooming. An aperture stop is provided between the second lens group and the third lens group, and the third lens group includes a first partial group having a positive refractive power and a second partial group having a positive or negative refractive power, At the time of focusing, at least the first partial group moves on the optical axis.

  FIG. 1 is a lens cross-sectional view when focusing on an object at infinity at the wide angle end (short focal length end) of the zoom lens according to Embodiment 1 of the present invention. 2A, 2B, and 2C show longitudinal aberrations when an object at infinity is focused at the wide-angle end, the intermediate zoom position, and the telephoto end (long focal length end) of the zoom lens of Embodiment 1, respectively. FIG. FIGS. 3A, 3B, and 3C show finite distances at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Embodiment 1 (the image plane when a numerical embodiment described later is expressed in mm). It is a longitudinal aberration diagram when focusing on 700 mm).

  FIG. 4 is a lens cross-sectional view when focusing on an object at infinity at the wide-angle end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 5A, 5B, and 5C are longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Embodiment 2, respectively. 6A, 6B, and 6C show finite distances at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 2 (image planes when numerical examples described later are expressed in mm). It is a longitudinal aberration diagram when focusing on 700 mm).

  FIG. 7 is a lens cross-sectional view when focusing on an object at infinity at the wide-angle end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 8A, 8B, and 8C are longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 3, respectively. FIGS. 9A, 9B, and 9C show finite distances at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 3 (image planes when numerical examples to be described later are expressed in mm). It is a longitudinal aberration diagram when focusing on 700 mm).

  FIG. 10 is a lens cross-sectional view when focusing on an object at infinity at the wide-angle end of the zoom lens according to Embodiment 4 of the present invention. FIGS. 11A, 11B, and 11C are longitudinal aberration diagrams when focusing on an object at infinity at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Embodiment 4, respectively. 12A, 12B, and 12C show finite distances at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 4 (the image plane when a numerical embodiment described later is expressed in mm). It is a longitudinal aberration diagram when focusing on 700 mm).

  FIG. 13 is a schematic diagram of a main part of a camera (imaging device) including the zoom lens of the present invention. The zoom lens of each embodiment is an imaging lens system used in an imaging apparatus such as a video camera, a digital camera, and a silver salt film camera.

  In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). In the lens cross-sectional view, i indicates the order of the lens groups from the object side, and Li is the i-th lens group. LR is a rear group having two or more lens groups. SP is an aperture stop, which is disposed between the second lens unit L2 and the third lens unit L3. L3A is a first partial group having a positive refractive power in a part of the third lens unit L3, and L3B is a second partial group having a negative refractive power in a part of the third lens unit L3.

  IP is an image plane. When used as an imaging optical system for a video camera or a digital still camera, an imaging plane of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor is arranged, and a camera for a silver salt film In this case, the film surface is arranged.

  In the spherical aberration diagram, the solid line d is d line, and the two-dot chain line g is g line. In the astigmatism diagram, the dotted line ΔM is the meridional image plane, and the solid line ΔS is the sagittal image plane. The lateral chromatic aberration is shown for the g-line. ω is a half angle of view (degree), and Fno is an F number. In the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the lens groups are positioned at both ends of a range in which the lens group can move on the optical axis. The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. An arrow related to focus indicates a moving direction during focusing from infinity to a short distance.

  The zoom lens of the present invention includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, a third lens unit L3 having a positive refractive power, and two or more. The rear lens group LR includes the lens group. The distance between adjacent lens units changes during zooming. The third lens unit L3 includes a first partial group L3A having a positive refractive power and a second partial group L3B having a positive or negative refractive power.

  At the time of focusing from infinity to a finite distance, at least the first partial group L3A moves along the optical axis. In each embodiment, the first partial group L3A has a high sensitivity, which is a ratio of the amount of movement along the optical axis of the image plane position to the amount of movement along the optical axis of the focus lens unit, and therefore the amount of focusing movement is small. So quick focusing is easy. Further, the first lens unit L3A having a positive refractive power, which is a focus lens unit, is arranged on the image side of the aperture stop SP, and the focus lens unit L3A is reduced in size by reducing the distance from the aperture stop SP. .

The i-th (i = 1 to n) lens group counted from the object side is the i-th lens group, and the lateral magnification of the i-th lens group at the telephoto end when it is focused at infinity is βiT, infinite. Let βiW be the lateral magnification of the i-th lens unit at the wide-angle end when focusing far away. ZR = (β3T × β4T ×... × βnT) / (β3W × β4W ×... ΒnW) is obtained by setting the combined zoom ratio ZR of the lens unit positioned on the image side relative to the second lens group.
And At this time,
3.00 <ZR <10.00 (1)
−2.50 <β2T <−0.90 (2)
The following conditional expression is satisfied.

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (1) relates to the combined zoom ratio by the lens unit existing on the image side of the second lens unit L2. If the lower limit of conditional expression (1) is not reached, it is difficult to increase the zoom ratio in the entire system. If the upper limit of conditional expression (1) is exceeded, the amount of movement during zooming of the lens unit on the image side relative to the second lens unit L2 increases and the refractive power increases, so that various aberrations increase. It becomes difficult to correct aberrations.

  Conditional expression (2) relates to the lateral magnification (imaging lateral magnification) of the second lens unit L2 at the telephoto end. If the upper limit of conditional expression (2) is exceeded, the change in the distance between the first lens unit L1 and the second lens unit L2 due to zooming increases, and the amount of extension during zooming of the first lens unit L1 at the telephoto end becomes too large. The mechanical mechanism becomes complicated. If the lower limit of conditional expression (2) is not reached, the positive refractive power of the first lens unit L1 becomes too strong, and spherical aberration and coma increase at the telephoto end, making it difficult to correct these various aberrations. More preferably, the numerical ranges of conditional expressions (1) and (2) should be as follows.

3.00 <ZR <6.00 (1a)
-2.50 <β2T <-1.00 (2a)
More preferably, the numerical ranges of the conditional expressions (1a) and (2a) should be as follows.
3.40 <ZR <5.00 (1b)
−2.00 <β2T <−1.00 (2b)

  According to each embodiment, by configuring as described above, it is possible to obtain a zoom lens in which the entire optical system is small in size and has a high zoom ratio and less aberration fluctuation during focusing. In each embodiment, it is more preferable to satisfy one or more of the following conditions. The focal length of the second lens unit L2 is f2, and the focal length of the entire system at the telephoto end when focusing on infinity is fT. Let the focal length of the first subgroup be fa. The zoom ratio Z2 of the second lens unit L2 is Z2 = β2T / β2W, and the zoom ratio of the entire system is Z.

Here, the zoom ratio Z of the entire system is expressed as follows:
Z = fT / fW
It is. Of the lenses included in the first partial group L3A, the refractive index and Abbe number of the material of one lens are nd3A and νd3A, respectively. At this time, one or more of the following conditional expressions should be satisfied.

−0.07 <f2 / fT <−0.03 (3)
0.02 <fa / fT <0.20 (4)
0.10 <Z2 / Z <0.35 (5)
nd3A> 1.50 (6)
νd3A> 55.0 (7)

  Next, the technical meaning of each conditional expression described above will be described. Conditional expression (3) relates to the negative refractive power of the second lens unit L2. When the upper limit of conditional expression (3) is exceeded and the negative refractive power of the second lens unit becomes too strong (when the absolute value of the negative refractive power increases), variations in various aberrations accompanying zooming increase. If the lower limit of conditional expression (3) is not reached and the negative refractive power becomes too weak (the absolute value of the negative refractive power becomes small), the variable magnification share of the second lens unit L2 becomes small, making it difficult to achieve a high zoom ratio. It becomes. Preferably, the numerical range of conditional expression (3) should be as follows.

−0.06 <f2 / fT <−0.03 (3a)
More preferably, the numerical range of conditional expression (3a) should be as follows.

−0.05 <f2 / fT <−0.03 (3b)
Conditional expression (4) relates to the positive refractive power of the focusing lens portion (first partial group) La. When the upper limit of conditional expression (4) is exceeded, the positive refractive power of the lens portion La at the telephoto end becomes weak, and the focus sensitivity decreases. On the other hand, if the lower limit of conditional expression (4) is not reached, the positive refractive power of the lens portion La becomes too strong, and variations in various aberrations accompanying focusing become large. More preferably, the numerical range of conditional expression (4) should be as follows.

0.05 <fa / fT <0.17 (4a)
More preferably, the numerical range of conditional expression (4a) should be as follows.

0.12 <fa / fT <0.17 (4b)
Conditional expression (5) relates to the variable magnification ratio sharing of the second lens unit L2. If the upper limit of conditional expression (5) is exceeded, the variable magnification ratio sharing of the second lens unit L2 becomes too large, and it becomes difficult to correct aberration fluctuations in the second lens unit L2. If the lower limit of conditional expression (5) is not reached, the variable magnification ratio sharing by other lens units becomes too large, and aberrations that occur outside the second lens unit L2 become large, making it difficult to correct these. More preferably, the numerical range of conditional expression (5) should be as follows.

0.10 <Z2 / Z <0.34 (5a)
More preferably, the numerical range of conditional expression (5a) should be as follows.

0.25 <Z2 / Z <0.34 (5b)
Conditional expressions (6) and (7) relate to the material of one lens in the first partial group L3A which is a focusing lens part. A deviation from the numerical range of the conditional expressions (6) and (7) is not preferable because fluctuations in chromatic aberration accompanying focusing increase. More preferably, the numerical ranges of conditional expressions (6) and (7) should be as follows.

nd3A> 1.54 (6a)
νd3A> 58.0 (7a)

  Next, the lens configuration of each example will be described. In each embodiment, in order from the object side to the image side, the first lens unit L1 having a positive refractive power, the second lens unit L2 having a negative refractive power, the third lens unit L3 having a positive refractive power, two or more A rear group LR including a lens group is included. An aperture stop SP is provided between the second lens unit L2 and the third lens unit L3.

  In Example 1, the rear group LR includes, in order from the object side to the image side, a fourth lens unit L4 having a negative refractive power, a fifth lens unit L5 having a positive refractive power, and a sixth lens unit L6 having a negative refractive power. Each lens group moves during zooming. During focusing from infinity to a short distance, the first subgroup L3A moves to the image side. The first partial group L3A corresponds to the lens portion La.

  In Example 2, the rear lens group LR includes a fourth lens unit L4 having a negative refractive power and a fifth lens unit L5 having a positive refractive power in order from the object side to the image side, and each lens unit moves during zooming. . During focusing from infinity to a short distance, the first subgroup L3A moves to the image side. The first partial group L3A corresponds to the lens portion La.

  In Example 3, the rear lens group LR includes a fourth lens unit L4 having a positive refractive power and a fifth lens unit L5 having a negative refractive power in order from the object side to the image side, and each lens unit moves during zooming. . During focusing from infinity to a short distance, the first subgroup L3A moves to the image side. The first partial group L3A corresponds to the lens portion La.

  In Example 4, the rear lens group LR includes, in order from the object side to the image side, a fourth lens unit L4 having a positive refractive power, a fifth lens unit L5 having a negative refractive power, and a sixth lens unit L6 having a negative refractive power. Each lens group moves during zooming. During focusing from infinity to short distance, the first partial group L3A moves to the image side, and the second partial group L3B moves to the object side. Example 4 uses a floating system to reduce aberration fluctuations during focusing. In Example 4, the second partial group L3B performs the focusing movement at a ratio of −0.87 times with respect to the first partial group L3A which is the main focus lens unit.

  Next, the configuration of each lens group in each embodiment will be described. Hereinafter, it is assumed that each lens group is arranged in order from the object side to the image side.

  The lens configuration of Example 1 will be described. The first lens unit L1 includes a cemented lens obtained by bonding a meniscus negative lens having a convex surface facing the object side and a positive lens, and a meniscus positive lens having a convex surface facing the object side. Thereby, coma aberration, spherical aberration at the telephoto end, etc. are corrected well.

  The second lens unit L2 includes a meniscus negative lens having a convex surface facing the object side, a negative lens having a concave shape on both lens surfaces, a positive lens having a convex shape on both lens surfaces, a negative lens, and a positive lens. . Thereby, aberration variation is reduced in the entire zoom range, and good optical performance is achieved. The second lens unit L2 has an aspheric lens having at least one aspheric surface. This facilitates correction of field curvature at the wide-angle end. In particular, it is more desirable that the most object side lens surface of the second lens unit L2 be aspherical.

  The third lens unit L3 includes a first partial group L3A having a positive refractive power and a second partial group L3B having a positive refractive power. In the third exemplary embodiment, the third A lens unit L3A includes one positive lens. The first partial group L3A is not limited to one, and the first partial group L3A may be composed of two or more lenses. The second partial group L3B includes a positive lens and a cemented lens in which a negative lens and a positive lens are cemented. The second partial group L3B has a positive refractive power, but may have a negative refractive power.

  The fourth lens unit L4 includes a cemented lens in which a positive lens and a meniscus negative lens having a convex surface facing the image surface are cemented. The fourth lens unit L4 includes an aspheric lens having at least one aspheric surface. This facilitates correction of distortion at the wide angle end. The fifth lens unit L5 includes a positive lens, a cemented lens in which a negative lens having a concave surface facing the image surface side, and a positive lens are cemented together, and a positive lens. The sixth lens unit L6 includes a cemented lens in which a positive lens having a convex surface directed toward the object side and a negative lens having concave surfaces on both lens surfaces are cemented.

  In this embodiment, the fourth lens unit L4 is composed of a cemented lens having a negative refractive power as a whole, so that the lens configuration including the third lens unit L3 and the fourth lens unit L4 is a telephoto type. . As a result, the space for zooming of the second lens unit L2 is increased to facilitate a high zoom ratio.

  The lens configuration of Example 2 will be described. In Example 2, the lens configurations of the first lens unit L1, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 are the same as those in Example 1. The fifth lens unit L5 is a positive lens, a cemented lens in which a negative meniscus lens having a concave surface facing the image side, and a positive lens having convex surfaces on both lens surfaces, and a negative lens having both concave surfaces and an object side surface. It is composed of a bonded lens obtained by cementing a convex positive lens.

  The lens configuration of Example 3 will be described. In Example 3, the lens configuration of the first partial group L3A of the first lens unit L1, the second lens unit L2, and the third lens unit L3 is the same as that of Example 1. The second partial group L3B includes a cemented lens in which a negative lens and a positive lens are cemented, and a cemented lens in which a positive lens and a negative lens are cemented. The fourth lens unit L4 includes a positive lens, a cemented lens in which a negative meniscus lens and a positive lens are cemented, and a positive lens. The fifth lens unit L5 includes a cemented lens obtained by cementing a meniscus negative lens and a positive lens, and a negative lens.

  The lens configuration of Example 4 will be described. In Example 4, the lens configurations of the first lens unit L1 to the sixth lens unit L6 are the same as those in Example 1.

  Next, an embodiment in which the zoom lens shown in Examples 1 to 4 is applied to a photographing apparatus will be described with reference to FIG. FIG. 13 is a schematic view of a single-lens reflex camera. In FIG. 13, reference numeral 10 denotes an interchangeable lens having the taking lens 1 of Examples 1 to 4. The photographing lens 1 is held by a lens barrel 2 that is a holding member.

  Reference numeral 20 denotes a camera body, which includes a quick return mirror 3 that reflects a light beam from the photographing lens 1 upward, and a focusing screen 4 that is disposed at an image forming position of the photographing lens 1. It comprises a penta roof prism 5 that converts a reverse image formed on the focusing screen 4 into an erect image, an eyepiece 6 for observing the erect image, and the like. Reference numeral 7 denotes an image pickup surface on which an image pickup element that receives an image is arranged. At the time of shooting, the quick return mirror 3 is retracted from the optical path, and an image is formed on the imaging surface 7 by the shooting lens 1.

  In the following, numerical examples 1 to 4 corresponding to the first to fourth examples will be described. In each numerical example, i indicates the order of the surfaces from the object side, ri is the radius of curvature of the i-th (i-th surface) surface, di is the distance between the i-th surface and the i + 1-th surface, and ndi , Νdi indicate the refractive index and Abbe number based on the d-line of the i-th lens material, respectively. BF is a back focus, which is a distance in terms of air from the final lens surface to the image plane. The total lens length is obtained by adding the back focus value to the distance from the first lens surface to the final lens surface. The aspheric data shows the aspheric coefficient when the aspheric surface is expressed by the following equation.

However,
x: Displacement amount from the reference plane in the optical axis direction h: Height in the direction perpendicular to the optical axis R: Radius of the quadric surface as a base k: Conical constant An: n-th order aspheric coefficient The display of “ ^ez ” means “10 ^−Z ”. Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.

[Numerical Example 1]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 230.390 2.50 1.90366 31.3 109.04
2 114.555 14.24 1.49700 81.5 101.28
3 -4479.960 0.15 99.11
4 104.627 12.50 1.59282 68.6 90.20
5 * -2716.177 (variable) 89.45
6 * 90.646 0.10 1.52421 51.4 52.50
7 90.646 1.90 1.88300 40.8 50.99
8 30.490 11.05 41.14
9 -83.184 1.80 1.88300 40.8 40.32
10 48.549 0.62 37.61
11 56.544 8.75 1.80809 22.8 37.62
12 -51.768 0.89 37.08
13 -42.792 1.80 1.85400 40.4 36.83
14 * 87.205 0.19 35.91
15 70.473 3.82 1.85478 24.8 35.98
16 524.273 (variable) 35.64
17 (Aperture) ∞ 1.00 37.75
18 * 105.132 5.37 1.58313 59.4 39.20
19 * -84.744 25.15 39.47
20 51.693 5.61 1.60311 60.6 41.00
21 1737.824 0.15 40.57
22 210.357 1.40 1.90366 31.3 40.12
23 32.950 8.71 1.60311 60.6 38.00
24 -143.671 (variable) 37.80
25 -131.457 4.73 1.67270 32.1 28.63
26 -29.394 1.40 1.80 400 46.6 28.23
27 * 83.737 (variable) 27.55
28 727.312 4.53 1.51633 64.1 35.47
29 -62.571 0.15 36.00
30 88.226 1.50 1.90366 31.3 36.84
31 31.680 9.07 1.48749 70.2 36.25
32 -112.148 0.20 36.74
33 42.940 6.38 1.65412 39.7 38.12
34 2557.983 (variable) 37.62
35 2642.657 6.85 1.85478 24.8 35.09
36 -34.483 1.50 1.85400 40.4 34.60
37 * 43.500 (variable) 32.48
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = 3.67299e-008 A 6 = -1.58484e-012
A 8 = 1.81821e-016 A10 = -1.63138e-021

6th page
K = 0.00000e + 000 A 4 = -2.43977e-006 A 6 = 5.09375e-010
A 8 = 1.82573e-012 A10 = -3.53421e-015 A12 = 2.03436e-018

14th page
K = 0.00000e + 000 A 4 = -2.11365e-006 A 6 = 1.55548e-009
A 8 = 1.98487e-013 A10 = -2.35384e-016

18th page
K = 0.00000e + 000 A 4 = -8.84286e-007 A 6 = 2.46880e-010
A 8 = 2.24946e-012 A10 = -3.85826e-015

19th page
K = 0.00000e + 000 A 4 = 5.08795e-007 A 6 = -1.66557e-010
A 8 = 2.78728e-012 A10 = -4.24540e-015

27th page
K = 0.00000e + 000 A 4 = -2.92197e-006 A 6 = 1.19104e-009
A 8 = -8.67072e-012 A10 = 1.47872e-014

37th page
K = 0.00000e + 000 A 4 = 5.79640e-008 A 6 = -1.39003e-009
A 8 = 3.99401e-012 A10 = -8.21714e-015

Various data Zoom ratio 18.78
Wide angle Medium Telephoto focal length 28.80 139.49 540.91
F number 2.88 4.77 5.88
Half angle of view (degrees) 36.91 8.82 2.29
Image height 21.64 21.64 21.64
Total lens length 298.13 341.13 398.13
BF 44.99 76.94 116.58

d 5 1.82 61.81 96.51
d16 77.88 26.98 6.99
d24 2.11 16.33 26.79
d27 21.26 5.73 5.25
d34 6.07 9.33 1.99
d37 44.99 76.94 116.58

Entrance pupil position 58.29 236.15 580.16
Exit pupil position -91.40 -59.82 -61.80
Front principal point position 81.01 233.36 -519.19
Rear principal point position 16.19 -62.55 -424.33

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 158.18 29.39 9.96 -9.01
2 6 -24.15 30.92 7.07 -14.02
3 17 51.97 47.39 18.49 -26.59
4 25 -51.38 6.13 2.43 -1.13
5 28 40.85 21.83 8.17 -6.29
6 35 -51.93 8.35 4.58 0.08

Single lens Data lens Start surface Focal length
1 1 -254.74
2 2 224.98
3 4 170.22
4 6 455754.35
5 7 -52.81
6 9 -34.50
7 11 34.70
8 13 -33.40
9 15 94.88
10 18 81.31
11 20 88.23
12 22 -43.40
13 23 45.28
14 25 55.25
15 26 -26.91
16 28 111.80
17 30 -55.40
18 31 51.74
19 33 66.70
20 35 39.87
21 36 -22.33

Focus wide angle end infinity 700mm
d19 25.15 21.94

Middle infinity 700mm
d19 25.15 18.09

Telephoto end infinity 700mm
d19 25.15 0.99

[Numerical Example 2]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 217.431 2.50 1.90366 31.3 103.92
2 111.459 12.75 1.49700 81.5 96.68
3 1582.531 0.15 94.22
4 110.018 12.84 1.59282 68.6 90.39
5 * -759.552 (variable) 89.73
6 * 80.453 0.10 1.52421 51.4 49.09
7 80.453 1.90 1.88300 40.8 47.56
8 29.244 10.39 38.67
9 -72.841 1.80 1.88300 40.8 37.82
10 46.373 0.47 35.28
11 52.369 8.74 1.80809 22.8 35.29
12 -43.880 0.80 34.74
13 -37.319 1.80 1.85400 40.4 34.34
14 * 127.600 0.14 33.52
15 70.928 2.96 1.80809 22.8 33.57
16 167.782 (variable) 33.96
17 (Aperture) ∞ 1.00 38.35
18 * 101.881 5.70 1.58313 59.4 39.28
19 * -74.740 21.55 39.45
20 64.234 5.03 1.62299 58.2 41.03
21 1658.547 0.15 40.64
22 142.261 1.40 1.85478 24.8 40.14
23 36.118 8.57 1.51742 52.4 38.39
24 -114.316 (variable) 38.21
25 -78.145 3.79 1.69895 30.1 28.60
26 -32.502 1.40 1.76802 49.2 28.31
27 * 110.496 (variable) 27.70
28 53.176 6.41 1.48749 70.2 39.26
29 -197.677 0.15 39.29
30 67.235 1.50 1.85478 24.8 39.02
31 33.614 10.06 1.48749 70.2 37.66
32 -78.655 4.95 37.51
33 * -230.699 1.50 1.85400 40.4 35.32
34 22.577 9.06 1.85478 24.8 35.00
35 123.841 (variable) 34.94
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = 5.43447e-008 A 6 = -3.82639e-012
A 8 = 9.22131e-016 A10 = -1.40964e-019

6th page
K = 0.00000e + 000 A 4 = -3.29136e-006 A 6 = 2.12735e-009
A 8 = -2.08405e-012 A10 = 1.85775e-016 A12 = 1.12522e-018

14th page
K = 0.00000e + 000 A 4 = -2.72281e-006 A 6 = 1.79935e-009
A 8 = 1.09079e-012 A10 = -3.02736e-015

18th page
K = 0.00000e + 000 A 4 = -1.08691e-006 A 6 = 8.70394e-010
A 8 = -8.76563e-013 A10 = 5.10406e-016

19th page
K = 0.00000e + 000 A 4 = 4.45307e-007 A 6 = 5.89903e-010
A 8 = -7.27751e-013 A10 = 5.34009e-016

27th page
K = 0.00000e + 000 A 4 = -2.88509e-006 A 6 = 2.62180e-009
A 8 = -1.34092e-011 A10 = 2.37302e-014

Side 33
K = 0.00000e + 000 A 4 = -3.53520e-006 A 6 = -8.36346e-010
A 8 = -1.52147e-012 A10 = -7.75132e-016

Various data Zoom ratio 18.78
Wide angle Medium Telephoto focal length 28.80 139.51 540.95
F number 2.88 4.77 5.88
Half angle of view (degrees) 36.91 8.82 2.29
Image height 21.64 21.64 21.64
Total lens length 298.12 341.12 398.12
BF 44.99 70.42 122.60

d 5 1.82 63.99 98.18
d16 76.25 27.49 6.97
d24 4.07 28.62 27.44
d27 31.42 11.03 3.37
d35 44.99 70.42 122.60

Entrance pupil position 55.90 242.25 585.92
Exit pupil position -139.47 -83.81 -65.85
Front principal point position 80.20 255.56 -425.96
Rear principal point position 16.19 -69.08 -418.36

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 159.01 28.24 9.53 -8.70
2 6 -22.63 29.11 7.35 -12.26
3 17 49.48 43.40 16.21 -24.38
4 25 -54.76 5.19 1.41 -1.57
5 28 88.06 33.63 -11.27 -29.50

Single lens Data lens Start surface Focal length
1 1 -255.94
2 2 240.56
3 4 163.00
4 6 359019.40
5 7 -52.95
6 9 -31.86
7 11 30.79
8 13 -33.64
9 15 150.00
10 18 74.82
11 20 107.13
12 22 -56.98
13 23 54.10
14 25 76.98
15 26 -32.56
16 28 86.68
17 30 -80.29
18 31 49.77
19 33 -24.01
20 34 31.02

Focus wide angle end infinity 700mm
d19 21.55 18.50

Middle infinity 700mm
d19 21.55 15.35

Telephoto end infinity 700mm
d19 21.55 0.98

[Numerical Example 3]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 227.303 2.50 1.90366 31.3 107.53
2 112.098 13.70 1.49700 81.5 99.77
3 2755.980 0.15 97.35
4 103.041 13.56 1.59282 68.6 90.49
5 * -1115.361 (variable) 89.63
6 * 93.066 0.10 1.52421 51.4 51.80
7 93.066 1.90 1.80 400 46.6 50.24
8 25.810 11.83 38.81
9 -74.988 1.80 1.88300 40.8 38.15
10 51.711 0.13 36.28
11 52.908 8.89 1.80809 22.8 36.28
12 -46.136 0.87 35.83
13 -38.876 1.80 1.85400 40.4 35.50
14 * 324.111 0.11 34.97
15 69.549 2.67 1.85478 24.8 34.76
16 118.111 (variable) 34.26
17 (Aperture) ∞ 1.00 37.65
18 * 87.434 5.09 1.55332 71.7 38.59
19 * -104.378 25.36 38.83
20 61.610 1.40 1.90366 31.3 41.67
21 46.602 8.86 1.48209 70.2 40.95
22 -77.999 2.11 40.81
23 -181.793 4.81 1.73958 28.1 39.18
24 -48.838 1.40 1.92389 35.4 38.91
25 * 86.375 (variable) 38.55
26 175.019 4.53 1.48749 70.2 39.16
27 -110.287 0.15 39.35
28 112.997 1.50 1.90366 31.3 39.32
29 34.975 8.90 1.51742 52.4 38.38
30 -132.313 0.20 38.59
31 40.653 7.76 1.51742 52.4 38.75
32 -573.251 (variable) 37.89
33 * 198.680 1.50 1.85400 40.4 33.79
34 72.587 6.54 1.85478 24.8 33.17
35 -66.102 0.20 32.61
36 -86.818 1.50 1.88300 40.8 31.85
37 35.047 (variable) 30.07
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = 5.10514e-008 A 6 = 1.32591e-012
A 8 = -1.53458e-015 A10 = 2.90146e-019

6th page
K = 0.00000e + 000 A 4 = -2.57039e-006 A 6 = 1.69112e-009
A 8 = -2.84281e-012 A10 = 2.38631e-015 A12 = -6.84024e-019

14th page
K = 0.00000e + 000 A 4 = -1.69344e-006 A 6 = 2.51617e-010
A 8 = 4.08846e-012 A10 = -6.30603e-015

18th page
K = 0.00000e + 000 A 4 = -2.81720e-006 A 6 = 7.25514e-009
A 8 = -2.05187e-011 A10 = 2.64753e-014

19th page
K = 0.00000e + 000 A 4 = -1.22264e-006 A 6 = 7.08625e-009
A 8 = -2.02097e-011 A10 = 2.63876e-014

25th page
K = 0.00000e + 000 A 4 = -7.78383e-007 A 6 = -4.36574e-010
A 8 = -2.73318e-013 A10 = 7.75043e-016

Side 33
K = 0.00000e + 000 A 4 = -1.65398e-006 A 6 = 5.37913e-010
A 8 = -8.05974e-012 A10 = 1.33590e-014

Various data Zoom ratio 18.78
Wide angle Medium Telephoto focal length 28.80 139.50 540.95
F number 2.88 4.77 5.88
Half angle of view (degrees) 36.91 8.82 2.29
Image height 21.64 21.64 21.64
Total lens length 298.14 341.14 398.14
BF 44.97 72.20 127.98

d 5 1.80 66.72 96.85
d16 76.42 23.96 6.95
d25 20.36 9.75 3.11
d32 11.76 25.68 20.43
d37 44.97 72.20 127.98

Entrance pupil position 57.17 265.17 600.06
Exit pupil position -73.31 -55.29 -46.94
Front principal point position 78.96 252.03 -531.89
Rear principal point position 16.17 -67.30 -412.98

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 156.45 29.92 10.11 -9.20
2 6 -23.46 30.09 6.56 -13.96
3 17 100.82 50.04 -29.70 -52.39
4 26 47.87 23.04 8.36 -7.23
5 33 -57.32 9.74 7.10 1.59

Single lens Data lens Start surface Focal length
1 1 -247.30
2 2 234.71
3 4 159.78
4 6 480414.51
5 7 -44.99
6 9 -34.43
7 11 31.77
8 13 -40.55
9 15 193.01
10 18 86.81
11 20 -221.51
12 21 61.95
13 23 88.92
14 24 -33.60
15 26 139.51
16 28 -56.57
17 29 54.45
18 31 73.68
19 33 -134.66
20 34 41.37
21 36 -28.11

Focus wide angle end infinity 700mm
d19 21.55 18.50

Middle infinity 700mm
d19 21.55 15.35

Telephoto end infinity 700mm
d19 21.55 0.98

[Numerical Example 4]
Unit mm

Surface data surface number rd nd νd Effective diameter
1 289.790 2.50 1.90366 31.3 102.34
2 134.350 13.41 1.49700 81.5 96.14
3 -1139.966 0.15 92.77
4 118.650 11.67 1.59282 68.6 90.57
5 * -2073.463 (variable) 89.82
6 * 75.928 0.10 1.52421 51.4 53.71
7 75.928 1.90 1.88300 40.8 51.20
8 28.624 11.37 41.92
9 -126.536 1.80 1.88300 40.8 41.44
10 59.477 0.57 39.58
11 66.394 7.20 1.80809 22.8 39.60
12 -63.122 1.29 39.37
13 -47.774 1.80 1.80400 46.6 39.08
14 * 93.656 0.18 38.40
15 102.870 3.33 1.80809 22.8 38.40
16 669.897 (variable) 38.11
17 (Aperture) ∞ 1.00 38.43
18 * 92.246 5.54 1.55332 71.7 39.31
19 * -85.593 25.31 39.37
20 51.079 6.28 1.48749 70.2 41.01
21 -432.507 0.15 40.63
22 126.145 1.40 1.90366 31.3 39.71
23 33.805 0.34 37.64
24 34.553 7.96 1.60311 60.6 37.77
25 -194.230 (variable) 37.49
26 -217.517 4.06 1.65434 33.5 28.74
27 -39.031 1.40 1.76474 51.7 28.19
28 * 58.210 (variable) 26.97
29 316.837 4.21 1.51633 64.1 34.21
30 -73.540 0.15 34.65
31 86.336 1.50 1.90366 31.3 35.26
32 30.441 8.63 1.48654 70.2 34.65
33 -113.446 0.20 35.11
34 46.392 5.86 1.63636 34.9 36.22
35 -891.649 (variable) 35.82
36 -194.883 6.34 1.85478 24.8 33.72
37 -30.536 1.50 1.85400 40.4 33.50
38 * 55.746 (variable) 32.53
Image plane ∞

Aspheric data 5th surface
K = 0.00000e + 000 A 4 = 2.84014e-008 A 6 = -1.18380e-012
A 8 = 2.09443e-016 A10 = -2.85359e-020

6th page
K = 0.00000e + 000 A 4 = -3.98126e-006 A 6 = 5.42455e-010
A 8 = -2.34915e-013 A10 = -5.50788e-017 A12 = 2.36553e-019

14th page
K = 0.00000e + 000 A 4 = -4.26526e-006 A 6 = 1.97757e-009
A 8 = -2.37855e-012 A10 = 1.73480e-015

18th page
K = 0.00000e + 000 A 4 = -1.16244e-006 A 6 = 1.06485e-009
A 8 = -1.88118e-012 A10 = 3.02521e-015

19th page
K = 0.00000e + 000 A 4 = 5.48269e-007 A 6 = 8.27860e-010
A 8 = -1.89648e-012 A10 = 3.28182e-015

28th page
K = 0.00000e + 000 A 4 = -2.51512e-006 A 6 = 5.00043e-010
A 8 = -3.17711e-012 A10 = 1.47098e-015

38th page
K = 0.00000e + 000 A 4 = -9.46815e-007 A 6 = -1.07379e-009
A 8 = 2.14780e-013 A10 = -1.43476e-017

Various data Zoom ratio 18.78
Wide angle Medium Telephoto focal length 28.80 139.51 540.95
F number 2.88 4.77 5.88
Half angle of view (degrees) 36.91 8.82 2.29
Image height 21.64 21.64 21.64
Total lens length 298.11 341.11 398.11
BF 39.99 68.21 106.95

d 5 1.82 69.06 106.97
d16 86.98 30.87 7.00
d25 1.64 18.98 26.36
d28 22.19 8.53 9.11
d35 6.39 6.37 2.64
d38 39.99 68.21 106.95

Entrance pupil position 58.12 250.65 596.24
Exit pupil position -78.94 -59.53 -61.98
Front principal point position 79.95 237.79 -595.10
Rear principal point position 11.19 -71.31 -434.00

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 172.97 27.73 9.99 -7.86
2 6 -25.78 29.54 7.48 -12.97
3 17 50.77 47.98 20.18 -26.69
4 26 -52.21 5.46 2.59 -0.63
5 29 43.03 20.55 7.83 -5.86
6 36 -50.09 7.84 3.24 -0.93

Single lens Data lens Start surface Focal length
1 1 -279.31
2 2 242.67
3 4 189.69
4 6 319766.36
5 7 -53.03
6 9 -45.61
7 11 41.06
8 13 -39.13
9 15 150.00
10 18 81.14
11 20 94.11
12 22 -51.47
13 24 49.28
14 26 72.05
15 27 -30.36
16 29 116.02
17 31 -52.70
18 32 50.32
19 34 69.47
20 36 41.62
21 37 -22.92

Focus wide angle end infinity 700mm
d19 25.31 24.49
d25 1.64 2.35

Middle infinity 700mm
d19 25.31 17.77
d25 18.98 19.69

Telephoto end infinity 700mm
d19 25.31 1.00
d25 26.36 27.07

LR Rear group L1 First lens group L2 Second lens group L3 Third lens group L3A First partial group L3B Second partial group L4 Fourth lens group L5 Fifth lens group L6 Sixth lens group

Claims (11)

In order from the object side to the image side, there is a rear lens group including a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and two or more lens groups. A zoom lens in which an interval between adjacent lens groups changes during zooming, and has an aperture stop between the second lens group and the third lens group, and the third lens group has a positive refractive power. The first partial group and a second partial group having positive or negative refractive power, and at the time of focusing, at least the first partial group moves on the optical axis and is counted from the object side to the i-th (i = 1). ˜n) is the i-th lens group, and the lateral magnification of the i-th lens group at the telephoto end when focusing at infinity is βiT, and at the wide-angle end when focusing at infinity. The lateral magnification of the i-th lens group is βiW, and the lens is located closer to the image side than the second lens group The combined zoom ratio ZR of the group is ZR = (β3T × β4T ×... ΒβT) / (β3W × β4W ×... × βnW)
And when
3.00 <ZR <10.00
−2.50 <β2T <−0.90
A zoom lens satisfying the following conditional expression: When the focal length of the second lens group is f2, and the focal length of the entire system at the telephoto end when focusing on infinity is fT,
−0.07 <f2 / fT <−0.03
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the focal length of the first subgroup is fa and the focal length of the entire system at the telephoto end is fT
0.02 <fa / fT <0.20
The zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied. When the zoom ratio Z2 of the second lens group is Z2 = β2T / β2W and the zoom ratio of the entire system is Z,
0.10 <Z2 / Z <0.35
The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied. When the refractive index and Abbe number of the material of one lens among the lenses included in the first partial group are nd3A and νd3A, respectively.
nd3A> 1.50
νd3A> 55.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   The zoom lens according to any one of claims 1 to 5, wherein the first partial group includes one positive lens.   The rear group includes, in order from the object side to the image side, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens group having a negative refractive power. The zoom lens according to any one of claims 1 to 6, wherein a group moves, and the first partial group moves toward the image side during focusing from infinity to a short distance.   The rear group includes, in order from the object side to the image side, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens group having a negative refractive power. The group moves, the first partial group moves to the image side, and the second partial group moves to the object side during focusing from infinity to a short distance. Zoom lens of the term.   The rear group includes, in order from the object side to the image side, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power, and each lens group moves during zooming, from infinity to a short distance. The zoom lens according to claim 1, wherein the first partial group moves toward the image side during focusing.   The rear group includes, in order from the object side to the image side, a fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, and each lens group moves during zooming, from infinity to a short distance. The zoom lens according to claim 1, wherein the first partial group moves toward the image side during focusing.   An image pickup apparatus comprising: the zoom lens according to claim 1; and an image pickup element that receives an image formed by the zoom lens.