JP2016057444A - Zoon lens and imaging device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens small in the whole optical system and having a high zoom ratio, in which high optical performance can be easily obtained over the whole zoom range.SOLUTION: A zoom lens comprises, sequentially from an object side to an image side: a first lens group L1 having positive refractive power; a second lens group L2 having negative refractive power; and a rear group comprising one or more lens groups. Upon zooming, a distance between adjoining lens groups varies. The first lens group has a diffractive surface DOE. A focal length ft of the whole system at the telephoto end, a focal length f1 of the first lens group, a focal length fdoe of the diffractive surface, and a lens whole length Lt at a telephoto end satisfy conditional formulae of 0.2<f1/ft<0.4, 0.40<Lt/ft<0.68, and 10.0<fdoe/f1<400.0.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a zoom lens and an image pickup apparatus having the same, and is particularly suitable for an image pickup optical system of an image pickup apparatus such as a still camera, a video camera, a digital still camera, a TV camera, and a surveillance camera.

  An imaging optical system used in an imaging apparatus is required to have a short overall lens length and a small overall system. In particular, a zoom lens has a high zoom ratio and high optical performance over the entire zoom range. It is requested.

  As a zoom lens that easily achieves a high zoom ratio, a positive lead type zoom lens in which a lens group having a positive refractive power is disposed closest to the object side is known. In a positive lead type zoom lens, various aberrations increase as the total lens length is shortened and the entire system is made smaller. In particular, chromatic aberrations such as axial chromatic aberration and lateral chromatic aberration increase, and optical performance tends to deteriorate.

  Conventionally, a positive lead type zoom lens using a diffractive optical element having a diffractive action in order to reduce the occurrence of chromatic aberration is known (Patent Documents 1 and 2). Patent Documents 1 and 2 are composed of first to seventh lens groups having positive, negative, positive, negative, positive, negative, and positive refractive power in order from the object side to the image side, and adjacent lens groups for zooming. A zoom lens is disclosed in which the interval between the zoom lenses is changed. Patent Documents 1 and 2 disclose a zoom lens in which the entire system is reduced in size while chromatic aberration is favorably corrected using a diffractive optical element in the first lens group.

JP 2011-90099 A JP 2004-317867 A

  In a positive lead type zoom lens, the chromatic aberration is corrected using a diffractive optical element while reducing the size of the entire system, and in order to obtain high optical performance in the entire zoom range, the zoom type, power of each lens group, and diffraction It is necessary to appropriately set the power of the optical element. If these configurations are not appropriate, it is difficult to obtain a zoom lens that corrects chromatic aberration well while achieving downsizing of the entire system and has high optical performance over the entire zoom range. For example, the total lens length (distance from the first lens surface to the image plane) increases at the telephoto end.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens and an image pickup apparatus having the zoom lens in which the entire optical system is small, has a high zoom ratio, and can easily obtain high optical performance over the entire zoom range.

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, and a rear group including one or more lens groups.
A zoom lens in which the interval between adjacent lens groups changes during zooming,
The first lens group has a diffractive surface;
Ft, the focal length of the entire system at the telephoto end
The focal length of the first lens group is f1,
The focal length of the diffractive surface is fdoe,
When the total lens length at the telephoto end is Lt,
0.2 <f1 / ft <0.4
0.40 <Lt / ft <0.68
10.0 <fdoe / f1 <400.0
It satisfies the following conditional expression.

  According to the present invention, it is possible to obtain a zoom lens in which the entire optical system is small, has a high zoom ratio, and can easily obtain high optical performance over the entire zoom range.

(A), (B) Lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 1 of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens according to Embodiment 1 of the present invention. (A), (B) Lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 2 of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 2 of the present invention. (A), (B) Lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 3 of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 3 of the present invention. (A), (B) Lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 4 of the present invention. (A), (B), (C) Aberration diagrams at the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens according to Embodiment 4 of the present invention. Schematic diagram of imaging device 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, and a rear group including one or more lens groups. The distance between adjacent lens groups changes during zooming. The rear group, in order from the object side to the image side, is a third lens group having a positive refractive power, 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. And a seventh lens unit having a positive refractive power. The first lens group has a diffractive surface.

  FIGS. 1A and 1B are lens cross-sectional views at the wide-angle end (short focal length end) and the telephoto end (long focal length end) of the zoom lens according to Embodiment 1 of the present invention. FIGS. 2A, 2B, and 2C are longitudinal aberration diagrams when focusing at infinity at the wide-angle end and the intermediate zoom position and the telephoto end according to the first embodiment of the present invention. The first embodiment is a zoom lens having a zoom ratio of 5.59 and an F number of 4.65 to 5.85.

  3A and 3B are lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 2 of the present invention. FIGS. 4A, 4B, and 4C are longitudinal aberration diagrams when focusing at infinity at the wide-angle end and the intermediate zoom position and the telephoto end according to the second embodiment of the present invention. The second embodiment is a zoom lens having a zoom ratio of 5.90 and an F number of 4.65 to 5.85.

  5A and 5B are lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 3 of the present invention. FIGS. 6A, 6B, and 6C are longitudinal aberration diagrams when focusing at infinity at the wide-angle end and the intermediate zoom position and the telephoto end according to the third embodiment of the present invention. The third embodiment is a zoom lens having a zoom ratio of 3.78 and an F number of 4.65 to 6.40.

  7A and 7B are lens cross-sectional views at the wide-angle end and the telephoto end of the zoom lens according to Embodiment 4 of the present invention. FIGS. 8A, 8B, and 8C are longitudinal aberration diagrams when focusing at infinity at the wide-angle end and the intermediate zoom position and the telephoto end according to the fourth embodiment of the present invention. The fourth embodiment is a zoom lens having a zoom ratio of 5.73 and an F number of 4.65 to 5.85. FIG. 9 is a schematic diagram of a main part of a video camera (imaging device) including the zoom lens of the present invention.

  In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The zoom lens of each embodiment is a photographic lens system used in an imaging apparatus such as a video camera or a digital camera. When the zoom lens of each embodiment is used as a projection lens such as a projector, the left side is the projection surface (screen) side, and the right side is the original image side projected on the projection surface.

  In the lens cross-sectional view, L1 is a first lens group having a positive refractive power, L2 is a second lens group having a negative refractive power, and LR is a rear group having one or more lens groups. The rear group LR includes a third lens unit L3 having a positive refractive power, 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. And a seventh lens unit L7 having a positive refractive power.

  Here, the refractive power is optical power = reciprocal of focal length. DOE is a diffractive surface. SP is an aperture stop, which is disposed on the image side of the third lens unit L3. IP is an image plane. When used as a photographing optical system for a video camera or a digital still camera, an imaging surface of a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor, or a camera for a silver salt film It corresponds to a photosensitive surface such as a film surface.

  The arrows indicate the movement trajectory of each lens unit during zooming from the wide-angle end to the telephoto end. During zooming, the first lens unit L1, the third lens unit L3, the fourth lens unit L4, and the sixth lens unit L6 move along different paths. During focusing from infinity to a short distance, the sixth lens unit L6 moves to the image side.

  In the spherical aberration diagram, d is the d-line (wavelength 587.56 nm), and g is the g-line (wavelength 435.8 nm). In the astigmatism diagram, ΔM is a meridional image plane relating to the d line, and ΔS is a sagittal image plane. The lateral chromatic aberration is represented by the g-line. Fno is the F number, and ω is the half angle of view. In the following embodiments, the wide-angle end and the telephoto end refer to zoom positions when the zoom lens unit is positioned at both ends of the range in which the zoom lens unit can move on the optical axis.

  The zoom lens of each embodiment includes a first lens unit L1 having a positive refractive power, a second lens unit L2 having a negative refractive power, and a rear group LR including one or more lens units in order from the object side to the image side. . Here, the lens group means a lens system divided by a change in the lens interval in the optical axis direction accompanying zooming or focusing. In each embodiment, a lens system that moves in a direction having a component orthogonal to the optical axis at the time of image blur correction is also expressed as a lens group.

  In the zoom lens of the present invention, when zooming from the wide-angle end to the telephoto end, the first lens unit L1 and the second lens unit L2 are moved to perform main zooming. Among these, the first lens unit L1 includes a diffractive optical element having one or more diffractive surfaces DOE. The diffractive surface has anomalous dispersion characteristics that are difficult to achieve with a general optical material, and chromatic aberration is satisfactorily reduced when used in a zoom lens.

If the first lens unit L1 does not have a diffractive surface, it is difficult to correct chromatic aberration well while reducing the size of the zoom lens. The focal length of the entire system at the telephoto end is ft, the focal length of the first lens unit L1 is f1, the focal length of the diffractive surface DOE is fdoe, and the total lens length at the telephoto end is Lt. At this time,
0.2 <f1 / ft <0.4 (1)
0.40 <Lt / ft <0.68 (2)
10.0 <fdoe / f1 <400.0 (3)
The following conditional expression is satisfied. Next, the technical meaning of the above will be described.

  Conditional expression (1) specifies the positive refractive power of the first lens unit L1, thereby effectively converging light rays incident from the object side at the telephoto end and reducing the occurrence of various aberrations. This is intended to reduce the size of the device. If the positive refractive power of the first lens unit L1 becomes too strong beyond the lower limit of conditional expression (1), it will be advantageous for downsizing the entire system, but chromatic aberration, spherical aberration, coma, etc. at the telephoto end. As a result, it becomes difficult to correct these aberrations satisfactorily. When the upper limit is exceeded and the positive refractive power of the first lens unit L1 becomes too weak, the light condensing action by the first lens unit L1 is weakened, making it difficult to downsize the entire system.

  Conditional expression (2) is for appropriately setting the ratio of the total lens length at the telephoto end to the focal length of the entire system at the telephoto end, and mainly correcting chromatic aberration satisfactorily. When the lower limit of conditional expression (2) is exceeded, it is necessary to increase the refractive power of each lens group, and it becomes difficult to satisfactorily correct various aberrations including chromatic aberration. Furthermore, it is not preferable because the imaging performance greatly changes with respect to manufacturing errors. When the upper limit of conditional expression (2) is exceeded, the refractive power of each lens group becomes relatively weak, and it becomes difficult to reduce the size of the entire system while ensuring a predetermined zoom ratio.

  Conditional expression (3) is for satisfactorily correcting chromatic aberration by making the ratio between the focal length of the first lens unit L1 and the focal length of the diffractive surface DOE arranged in the first lens unit L1 appropriate. In general, when a lens group having a positive refractive power is configured, a negative lens made of a relatively highly dispersed material is used, and therefore, chromatic aberration on the short wavelength side tends to be over the reference wavelength. Further, the higher the dispersion of a general material, the larger the partial dispersion ratio on the short wavelength side. For this reason, when the power of the first lens unit L1 is relatively increased, it is difficult to satisfactorily correct chromatic aberration over the entire visible range.

  At this time, it becomes easy to satisfactorily reduce chromatic aberration by using a diffractive optical element using a diffractive surface. In each embodiment, a diffractive surface DOE is used for a lens unit having a positive refractive power, and chromatic aberration is favorably reduced by applying positive power to the diffractive surface DOE.

  When the lower limit of conditional expression (3) is exceeded and the power of the diffractive surface DOE becomes relatively stronger than the power of the first lens unit L1, chromatic aberration due to the action of the diffractive surface DOE becomes overcorrected. When the upper limit of conditional expression (3) is exceeded and the power of the diffractive surface DOE becomes relatively weak, the chromatic aberration is insufficiently corrected. Preferably, the numerical ranges of conditional expressions (1) to (3) are set as follows.

0.24 <f1 / ft <0.40 (1a)
0.44 <Lt / ft <0.67 (2a)
20.0 <fdoe / f1t <300.0 (3a)
More preferably, the numerical ranges of the conditional expressions (1a) to (3a) are set as follows.

0.28 <f1 / ft <0.39 (1b)
0.48 <Lt / ft <0.67 (2b)
30.0 <fdoe / f1t <250.0 (3b)
More preferably, the numerical ranges of the conditional expressions (1b) to (3b) are set as follows.

0.30 <f1 / ft <0.39 (1c)
0.50 <Lt / ft <0.66 (2c)
40.0 <fdoe / f1t <220.0 (3c)
In each embodiment, it is preferable to satisfy one or more of the following conditional expressions.

  Let the focal length of the second lens unit L2 be f2. Let the focal length of the third lens unit L3 be f3. Let the focal length of the fourth lens unit L4 be f4. A distance along the optical axis from the lens surface closest to the object side of the first lens unit L1 to the lens surface closest to the image side of the first lens unit L1 (configuration lens length) is defined as Lg1. At this time, one or more of the following conditional expressions should be satisfied.

−6.0 <f1 / f2 <−3.5 (4)
2.0 <f1 / f3 <4.5 (5)
−4.5 <f1 / f4 <−2.0 (6)
0.05 <Lg1 / f1 <0.25 (7)
Next, the technical meaning of each conditional expression described above will be described.

  In the zoom lens of each embodiment, the second lens unit L2 is responsible for main zooming. By specifying the refractive power of the second lens unit L2 so as to satisfy the conditional expression (4), it is possible to reduce the size of the entire system while increasing the amount of magnification of the second lens unit L2.

  When the lower limit of conditional expression (4) is exceeded, the refractive power of the second lens unit L2 becomes relatively strong, making it difficult to reduce the Petzval sum and increasing the curvature of field. If the upper limit of conditional expression (4) is exceeded, the refractive power of the second lens unit L2 becomes relatively weak, and the contribution of the second lens unit L2 to zooming becomes small, making it difficult to achieve a high zoom ratio. Become. Moreover, it becomes difficult to reduce the size of the entire system.

  More preferably, the numerical range of conditional expression (4) should be set as follows.

−5.9 <f1 / f2 <−3.5 (4a)
More preferably, the numerical range of conditional expression (4a) should be set as follows.

−5.8 <f1 / f2 <−3.5 (4b)
More preferably, the numerical range of conditional expression (4b) should be set as follows.

-5.7 <f1 / f2 <-3.6 (4c)
Conditional expressions (5) and (6) are mainly for correcting coma aberration and field curvature that change during zooming.

  When the lower limit of conditional expression (5) is exceeded and the positive power of the first lens unit L1 becomes relatively strong, it becomes difficult to satisfactorily correct spherical aberration and coma. When the upper limit of conditional expression (5) is exceeded and the positive power of the first lens unit L1 is relatively weakened, the total lens length at the telephoto end increases, making it difficult to downsize the entire system. When the lower limit of conditional expression (6) is exceeded and the negative power of the fourth lens unit L4 is relatively weakened, it becomes difficult to correct field curvature. When the upper limit of conditional expression (6) is exceeded and the positive power of the first lens unit L1 becomes relatively strong, it becomes difficult to satisfactorily correct spherical aberration and coma. More preferably, the numerical ranges of conditional expressions (5) and (6) should be set as follows.

2.2 <f1 / f3 <4.2 (5a)
−4.0 <f1 / f4 <−2.2 (6a)
More preferably, the numerical ranges of conditional expressions (5a) and (6a) should be set as follows.

2.4 <f1 / f3 <4.0 (5b)
−3.4 <f1 / f4 <−2.3 (6b)
More preferably, the numerical ranges of conditional expressions (5b) and (6b) should be set as follows.

2.6 <f1 / f3 <3.6 (5c)
-2.8 <f1 / f4 <-2.4 (6c)
Conditional expression (7) is for appropriately setting the lens thickness for giving the first lens unit L1 a desired positive refractive power. When the lower limit of conditional expression (7) is exceeded, the constituent lens length of the first lens unit L1 becomes too short, and it becomes difficult to give a desired refractive power to the first lens unit L1. If the length of the constituent lenses of the first lens unit L1 exceeds the upper limit value of the conditional expression (7), it is difficult to reduce the size of the entire system and the weight of the lens also increases. Preferably, the numerical range of conditional expression (7) is set as follows.

0.10 <Lg1 / f1 <0.20 (7a)
More preferably, the numerical range of conditional expression (7a) should be set as follows.

0.12 <Lg1 / f1 <0.18 (7b)
More preferably, the numerical range of conditional expression (7b) should be set as follows.

0.14 <Lg1 / f1 <0.16 (7c)
In each embodiment, when an aspheric lens is disposed in the second lens unit L2, it is easy to satisfactorily correct field curvature that varies with zooming. In each embodiment, it is preferable to arrange aspherical lenses in the third lens unit L3 and the fourth lens unit L4. According to this, it becomes easy to correct coma well at the telephoto end. Next, the lens configuration of the zoom lens of each embodiment will be described.

[Example 1]
The zoom lens according to the first exemplary embodiment 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 a negative lens unit. A fourth lens unit L4 having a refractive power of 5 and a fifth lens unit L5 having a positive refractive power. Further, the lens unit includes seven lens groups, a sixth lens unit L6 having a negative refractive power and a seventh lens unit L7 having a positive refractive power. During zooming, the first lens unit L1, the third lens unit L3, the fourth lens unit L4, and the sixth lens unit L6 move along different paths.

  Example 1 is a zoom lens having a focal length of 51.8 mm to 289.5 mm and a zoom ratio of 5.59. An arrow (solid line) in FIG. 1 indicates the movement locus of the lens unit when zooming from the wide-angle end to the telephoto end. During focusing from infinity to a short distance, the sixth lens unit L6 moves to the image side. Further, at the time of image blur correction, the second lens unit L2 moves in a direction having a component perpendicular to the optical axis.

  In Example 1, the first lens unit L1 is extended toward the object side during zooming. Then, by appropriately setting the power of the diffractive surface DOE arranged in the first lens unit L1, fluctuations in chromatic aberration during zooming are corrected well. In Example 1, an aspheric lens is arranged in the fourth lens unit L4. As a result, coma that fluctuates with zooming is reduced.

[Example 2]
The zoom lens of Example 2 includes the number of lens groups, the sign of the refractive power of each lens group, the movement of the lens group during zooming, the movement of the lens group during focusing, the movement of the lens group during image blur correction, and the diffraction surface. The position and optical action are the same as those in the first embodiment. Example 2 is a zoom lens having a focal length of 49.1 mm to 290.0 mm and a zoom ratio of 5.90 times. In Example 2, aspherical lenses are arranged in the second lens unit L2 and the fourth lens unit L4. As a result, coma and field curvature, which fluctuate during image blur correction, are reduced. Also, coma that varies with zooming is reduced.

[Example 3]
The zoom lens of Example 3 includes the number of lens groups, the sign of the refractive power of each lens group, the movement of the lens group during zooming, the movement of the lens group during focusing, the movement of the lens group during image blur correction, and the diffraction surface. The position and optical action are the same as those in the first embodiment. Example 3 is a zoom lens having a focal length of 50.9 mm to 192.5 mm and a zoom ratio of 3.78 times. In Example 3, an aspheric lens is disposed in the third lens unit L3. As a result, coma and field curvature that vary with zooming are reduced.

[Example 4]
The zoom lens of Example 4 includes the number of lens groups, the sign of the refractive power of each lens group, the movement of the lens group during zooming, the movement of the lens group during focusing, the movement of the lens group during image blur correction, and the diffraction surface. The position and optical action are the same as those in the first embodiment. Example 4 is a zoom lens having a focal length of 4.95 mm to 58.2 mm and a zoom ratio of 11.76 times. In Example 4, aspherical surfaces are arranged in the second lens unit L2 and the third lens unit L3. This reduces coma and field curvature that vary with zoom.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  A digital still camera (imaging device) using the zoom lens shown in each embodiment as a photographing optical system will be described with reference to FIG.

  In FIG. 9, reference numeral 20 denotes a camera body. Reference numeral 21 denotes a photographing optical system constituted by any one of the zoom lenses described in the first to fourth embodiments. Reference numeral 22 denotes a solid-state imaging device (photoelectric conversion device) such as a CCD sensor or a CMOS sensor that receives a subject image formed by the photographing optical system 21 and is built in the camera body.

  A memory 23 records information corresponding to a subject image photoelectrically converted by the solid-state imaging device 22. Reference numeral 24 denotes a finder for observing a subject image formed on the solid-state image sensor 22, which includes a liquid crystal display panel or the like. As described above, by using any one of the zoom lenses described in Embodiments 1 to 4 as a photographing optical system of a digital still camera, it is possible to provide a small zoom lens in which chromatic aberration is favorably corrected.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

(Numerical example)
Hereinafter, numerical examples 1 to 4 corresponding to the first to fourth examples will be described. In each numerical example, i indicates the number of the surface or optical element counted from the light incident side. For example, ri is the radius of curvature of the i-th optical surface (i-th surface). di is an axial distance between the i-th surface and the (i + 1) -th surface. The unit of ri and di is mm. ni and νdi respectively indicate the refractive index and Abbe number of the material of the i-th optical element with respect to the d-line. The refractive index is the refractive index of the Fraunhofer line for g line (435.8 nm), F line (486.1 nm), d line (587.6 nm) and C line (656.3 nm), respectively, ng, nF, nd. , NC.

  At this time, the Abbe number νd for the d-line and the partial dispersion ratio for the g-line and the F-line are respectively defined as follows.

νd = (nd−1) / (nF−nC)
θgF = (ng−nF) / (nF−nC)
In the present invention, the focal length and the like are expressed using the reference wavelength as the d-line.

  The aspherical shape with * next to the surface number is defined as follows: X is the amount of displacement from the surface vertex in the optical axis direction, h is the height from the optical axis in the direction perpendicular to the optical axis, and r is the paraxial curvature. When a radius is set, k is a conic constant, and Aj (j = 1, 2, 3...) Is an aspheric coefficient of each order, it is expressed by the following expression.

  The phase φ of the diffraction surface with (diffraction) beside the surface number is m as the diffraction order of the diffracted light, λ0 as the reference wavelength, and Cj (j = 1, 2, 3,...) As the phase coefficient of each order. When expressed by the following equation.

  The Abbe number νdDOE for the d-line of the diffractive surface and the partial dispersion ratio θgFDOE for the g-line and the F-line are as follows when the wavelengths of the d-line, g-line, C-line, and F-line are λd, λg, λC, and λF, respectively. It is expressed by the following formula.

νdDOE = λd / (λF−λC)
θgFDOE = (λg−λF) / (λF−λC)
Accordingly, the Abbe number νdDOE and the partial dispersion ratio θgFDOE are −3.45 and 0.296, respectively. The dispersion characteristic of the diffractive surface has a negative value, and has an action opposite to that of a general optical material. Further, the partial dispersion ratio θgFDOE between the g-line and the F-line is smaller than that of a general optical material, which means that the linearity of the refractive index change with respect to the wavelength is high. The focal length fDOE of the diffractive surface DOE is expressed by the following formula.

Further, the focal length fDOE (λ) of the diffractive surface at an arbitrary wavelength λ is expressed by the following equation.

“E ± XX” means “× 10 ^{± XX} ”. Fno is an effective F number. ω is a half angle of view, and the unit is degrees.

  Table 1 shows the lens data of each numerical example and the calculation results of the conditional expressions based thereon.

Numerical Example 1 (Example 1)
Surface number rd nd νd Effective diameter
1 97.703 4.29 1.59522 67.7 51.20
2 890.471 0.15 50.88
3 60.431 2.35 1.91082 35.3 48.98
4 41.358 0.05 1.56655 19.4 46.36
5 (Diffraction) 42.489 0.05 1.56655 19.4 46.43
6 42.489 8.84 1.48749 70.2 46.41
7 370.490 (variable) 45.26
8 ∞ 4.80 16.20
9 234.287 0.94 1.91082 35.3 13.86
10 31.323 1.82 13.44
11 -25.853 0.69 1.77250 49.6 13.41
12 24.962 2.02 1.84666 23.8 13.83
13 10398.557 (variable) 13.96
14 30.432 0.78 1.78472 25.7 14.43
15 18.835 3.87 1.56384 60.7 14.32
16 -30.711 1.01 14.36
17 (Aperture) ∞ (Variable) 13.92
18 * -15.019 0.80 1.58313 59.4 13.68
19 23.879 3.42 1.76182 26.5 14.82
20 -110.377 (variable) 15.24
21 -105.866 2.79 1.56384 60.7 16.73
22 -19.637 0.15 17.00
23 76.632 4.44 1.48749 70.2 16.54
24 -15.765 0.83 1.84666 23.8 16.20
25 -40.450 0.15 16.68
26 34.779 2.46 1.49700 81.5 16.91
27 -109.139 (variable) 16.81
28 -1013.896 0.75 1.80 400 46.6 14.99
29 21.200 0.00 14.71
30 21.200 (variable) 14.71
31 -930.962 2.72 1.80809 22.8 19.64
32 -29.735 1.04 1.80400 46.6 19.86
33 70.902 0.15 20.60
34 32.567 3.45 1.51742 52.4 21.39
35 -148.622 35.50 21.59
Image plane ∞

Diffraction surface data 5th surface (Diffraction surface)
C 2 = -6.92706e-005 C 4 = -2.80125e-008 C 6 = 4.90724e-011 C 8 = -1.10508e-013
C10 = 5.52358e-017 C12 = 1.49206e-020
Aspheric data 18th surface
K = 0.00000e + 000 A 4 = -3.71081e-006 A 6 = 1.66467e-007 A 8 = -3.39178e-009
A10 = 3.33329e-011

Various data Zoom ratio 5.59
Wide angle Medium Telephoto focal length 51.77 135.00 289.53
F number 4.65 5.05 5.85
Half angle of view (degrees) 14.78 5.78 2.70
Image height 13.66 13.66 13.66
Total lens length 126.05 169.37 184.15
BF 35.50 35.50 35.50

d 7 2.09 45.40 60.18
d13 9.09 6.49 1.00
d17 3.21 8.48 15.74
d20 5.65 2.98 1.21
d27 11.83 8.48 1.00
d30 3.87 7.23 14.71

Entrance pupil position 36.87 210.29 383.73
Exit pupil position -32.73 -39.89 -58.68
Front principal point position 49.36 103.56 -216.81
Rear principal point position -16.27 -99.50 -254.03

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 105.83 15.73 -1.34 -11.22
2 8 -18.78 10.27 6.23 -2.33
3 14 31.55 5.66 1.53 -2.47
4 18 -42.12 4.21 -0.87 -3.37
5 21 22.19 10.82 3.81 -3.55
6 28 -25.82 0.75 0.41 -0.01
7 31 136.65 7.35 3.78 -0.71

Single lens Data lens Start surface Focal length
1 1 184.01
2 3 -152.84
3 4 1964.16
4 5 6931.67
5 6 97.59
6 9 -39.78
7 11 -16.34
8 12 29.55
9 14 -64.91
10 15 21.31
11 18 -15.69
12 19 26.06
13 21 42.27
14 23 27.25
15 24 -30.99
16 26 53.37
17 28 -25.82
18 31 37.96
19 32 -25.94
20 34 51.97

Numerical Example 2 (Example 2)
Surface number rd nd νd Effective diameter
1 92.281 4.53 1.60311 60.6 50.51
2 1164.946 0.15 50.17
3 59.883 2.56 1.80610 33.3 48.14
4 40.224 0.05 1.56655 19.4 45.37
5 (Diffraction) 40.224 0.05 1.56655 19.4 45.35
6 40.224 8.32 1.48749 70.2 45.33
7 181.454 (variable) 44.14
8 * 134.215 0.70 1.88202 37.2 14.01
9 34.002 1.38 13.64
10 -48.027 0.69 1.77250 49.6 13.60
11 20.545 1.73 1.84666 23.8 13.62
12 59.717 (variable) 13.61
13 24.279 0.76 1.80518 25.4 13.88
14 16.565 3.43 1.60311 60.6 13.66
15 -56.570 1.00 13.53
16 (Aperture) ∞ (Variable) 13.12
17 * -14.322 0.69 1.58313 59.4 11.56
18 20.976 2.34 1.76182 26.5 12.36
19 -97.760 (variable) 12.58
20 -97.760 2.39 1.51633 64.1 14.13
21 -18.400 0.15 14.62
22 83.311 4.31 1.48749 70.2 15.07
23 -13.839 0.97 1.84666 23.8 15.22
24 -31.743 0.15 15.93
25 56.168 2.18 1.48749 70.2 16.19
26 -57.400 (variable) 16.19
27 -95.619 0.74 1.80 400 46.6 14.44
28 22.969 0.00 14.43
29 22.969 (variable) 14.43
30 871.980 3.07 1.92286 18.9 22.40
31 -34.394 1.17 1.88300 40.8 22.62
32 49.668 0.15 23.52
33 27.584 4.98 1.54072 47.2 25.18
34 -177.140 15.69 25.37
Image plane ∞

Diffraction surface data 5th surface (Diffraction surface)
C 2 = -6.02783e-005 C 4 = -1.42605e-008 C 6 = -3.56839e-011 C 8 = 1.86988e-013
C10 = -3.92506e-016 C12 = 2.74066e-019
Aspheric data 8th surface
K = 0.00000e + 000 A 4 = 1.46720e-007 A 6 = -6.16337e-009 A 8 = 4.28051e-010
A10 = -3.71500e-012
17th page
K = 0.00000e + 000 A 4 = -8.60403e-006 A 6 = 2.57813e-007 A 8 = -6.47428e-009
A10 = 8.45975e-011

Various data Zoom ratio 5.90
Wide angle Medium Telephoto focal length 49.13 135.00 290.00
F number 4.65 4.95 5.85
Half angle of view (degrees) 15.54 5.78 2.70
Image height 13.66 13.66 13.66
Total lens length 108.00 152.12 168.00
BF 15.69 15.69 15.69

d 7 4.24 48.37 64.24
d12 7.28 3.93 1.04
d16 3.10 9.54 14.74
d19 6.60 3.51 1.20
d26 17.97 12.81 1.02
d29 4.49 9.65 21.45

Entrance pupil position 31.70 190.03 372.35
Exit pupil position -33.05 -42.85 -65.55
Front principal point position 31.30 13.72 -372.87
Rear principal point position -33.44 -119.31 -274.31

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 106.26 15.65 -2.35 -12.05
2 8 -21.20 4.50 1.58 -1.44
3 13 32.09 5.19 0.72 -2.90
4 17 -42.05 3.03 -0.73 -2.54
5 20 22.36 10.14 3.84 -3.15
6 27 -22.97 0.74 0.33 -0.08
7 30 141.04 9.37 3.66 -1.96

Single lens Data lens Start surface Focal length
1 1 165.91
2 3 -161.36
3 4 7884.81
4 5 7878.08
5 6 104.00
6 8 -51.80
7 10 -18.55
8 11 36.26
9 13 -67.71
10 14 21.63
11 17 -14.49
12 18 22.86
13 20 43.45
14 22 24.70
15 23 -29.72
16 25 58.60
17 27 -22.97
18 30 35.91
19 31 -22.86
20 33 44.52

Numerical Example 3 (Example 3)
Surface number rd nd νd Effective diameter
1 70.274 2.19 1.56384 60.7 33.58
2 211.023 0.15 33.30
3 39.939 1.95 1.80610 33.3 32.00
4 27.955 0.05 1.56655 19.4 30.08
5 (Diffraction) 27.955 0.05 1.56655 19.4 30.05
6 27.955 6.87 1.48749 70.2 30.03
7 542.035 (variable) 28.63
8 89.494 0.67 1.85026 32.3 11.28
9 26.945 1.17 10.97
10 -37.466 0.57 1.80 400 46.6 10.94
11 18.199 1.67 1.84666 23.8 11.00
12 98.712 (variable) 11.02
13 19.412 0.68 1.80518 25.4 11.60
14 13.301 3.20 1.58313 59.4 11.45
15 * -39.523 0.90 11.42
16 (Aperture) ∞ (Variable) 11.16
17 -13.504 0.67 1.58913 61.1 10.74
18 21.213 1.73 1.80518 25.4 11.34
19 439.934 (variable) 11.47
20 -84.002 2.21 1.58313 59.4 13.04
21 -16.714 0.15 13.29
22 45.570 3.64 1.48749 70.2 13.17
23 -14.396 0.70 1.84666 23.8 13.31
24 -35.723 0.15 13.76
25 31.741 1.98 1.56384 60.7 14.10
26 -122.721 (variable) 14.06
27 -74.169 0.73 1.83481 42.7 12.68
28 20.997 1.95 12.71
29 -168.580 3.44 1.80518 25.4 13.22
30 -12.418 0.84 1.83481 42.7 13.76
31 63.390 (variable) 15.04
32 28.187 4.73 1.51823 58.9 26.00
33 -426.282 16.61 26.09
Image plane ∞

Diffraction surface data 5th surface (Diffraction surface)
C 2 = -9.09130e-005 C 4 = 6.09877e-009 C 6 = -2.28916e-010 C 8 = 4.60167e-013
Aspheric data 15th surface
K = 0.00000e + 000 A 4 = 6.78082e-006 A 6 = -2.12547e-008 A 8 = -4.89704e-010

Various data Zoom ratio 3.78
Wide angle Medium Tele focal length 50.92 100.00 192.50
F number 4.65 5.25 6.40
Half angle of view (degrees) 15.02 7.78 4.06
Image height 13.66 13.66 13.66
Total lens length 88.91 110.21 124.18
BF 16.61 16.61 16.61

d 7 2.39 23.68 37.66
d12 3.94 1.88 1.10
d16 2.46 7.07 10.30
d19 6.10 3.55 1.10
d26 12.08 9.18 0.89
d31 2.29 5.19 13.48

Entrance pupil position 22.78 78.75 175.63
Exit pupil position -27.49 -35.21 -62.70
Front principal point position 14.91 -14.24 -99.10
Rear principal point position -34.31 -83.39 -175.89

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 72.73 11.27 -0.61 -7.84
2 8 -19.74 4.08 1.27 -1.45
3 13 25.76 4.78 0.75 -2.61
4 17 -28.43 2.40 -0.05 -1.43
5 20 17.38 8.83 2.99 -2.96
6 27 -13.21 6.96 1.33 -3.16
7 32 51.20 4.73 0.19 -2.94

Single lens Data lens Start surface Focal length
1 1 185.82
2 3 -124.64
3 4 5133.32
4 5 5127.13
5 6 60.20
6 8 -45.57
7 10 -15.17
8 11 26.10
9 13 -55.21
10 14 17.46
11 17 -13.91
12 18 27.63
13 20 35.35
14 22 22.90
15 23 -28.91
16 25 44.93
17 27 -19.53
18 29 16.49
19 30 -12.38
20 32 51.20

Numerical Example 4 (Example 4)
Surface number rd nd νd Effective diameter
1 96.125 2.66 1.74950 35.3 49.56
2 (Diffraction) 57.005 0.10 1.52415 51.6 48.47
3 57.005 7.00 1.49700 81.5 48.45
4 -1515.068 0.15 48.30
5 66.151 4.99 1.48749 70.2 47.42
6 485.142 (variable) 46.99
7 ∞ 7.84 18.90
8 99.212 0.78 2.00 100 29.1 14.77
9 30.905 1.81 14.33
10 -36.084 0.73 1.88 100 40.1 14.28
11 20.521 2.39 1.92286 20.9 14.55
12 279.314 (variable) 14.64
13 24.679 0.81 1.84666 23.8 15.09
14 15.525 4.26 1.58313 59.4 14.81
15 * -42.829 1.20 14.73
16 (Aperture) ∞ (Variable) 14.23
17 * -17.411 0.72 1.58313 59.4 12.28
18 19.474 2.17 1.78472 25.7 12.95
19 276.925 (variable) 13.09
20 124.264 2.73 1.58913 61.1 15.00
21 -22.945 1.99 15.14
22 209.327 3.50 1.48749 70.2 14.32
23 -14.540 0.72 1.80518 25.4 14.04
24 -37.204 0.15 14.22
25 174.352 1.43 1.48749 70.2 14.37
26 -61.793 (variable) 14.44
27 -112.263 0.79 1.77250 49.6 14.78
28 24.360 (variable) 14.95
29 305.325 3.02 1.84666 23.8 24.73
30 -46.799 1.37 1.59522 67.7 24.96
31 36.752 0.55 25.78
32 24.195 5.90 1.48749 70.2 27.87
33 1014.120 15.38 27.82
Image plane ∞

Diffraction surface data 2nd surface (Diffraction surface)
C 2 = -2.44231e-005 C 4 = 7.33444e-009 C 6 = -7.71140e-012 C 8 = 2.83706e-015
Aspheric data 15th surface
K = 0.00000e + 000 A 4 = 2.93244e-006 A 6 = -2.08037e-008 A 8 = 5.77344e-011
17th page
K = 0.00000e + 000 A 4 = -8.29800e-006 A 6 = -8.39120e-008 A 8 = 1.40407e-009

Various data Zoom ratio 5.73
Wide angle Medium Telephoto focal length 50.60 135.02 289.92
F number 4.65 4.97 5.85
Half angle of view (degrees) 15.11 5.78 2.70
Image height 13.66 13.66 13.66
Total lens length 126.66 162.32 176.66
BF 15.38 15.38 15.38

d 6 5.71 41.37 55.71
d12 9.87 5.03 1.24
d16 3.04 11.31 17.64
d19 7.47 4.03 1.50
d26 20.47 15.92 1.20
d28 4.97 9.51 24.24

Entrance pupil position 48.01 188.23 348.83
Exit pupil position -41.87 -55.13 -105.58
Front principal point position 53.89 64.70 -56.12
Rear principal point position -35.22 -119.64 -274.54

Zoom lens group data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 99.95 14.90 3.32 -6.56
2 7 -20.41 13.55 9.37 -2.27
3 13 32.94 6.27 1.17 -3.26
4 17 -38.55 2.88 0.00 -1.66
5 20 24.48 10.52 3.33 -4.60
6 27 -25.85 0.79 0.37 -0.08
7 29 85.75 10.83 2.29 -4.74

Single lens Data lens Start surface Focal length
1 1 -194.31
2 2 18374.30
3 3 110.70
4 5 156.51
5 8 -45.10
6 10 -14.76
7 11 23.89
8 13 -51.53
9 14 20.08
10 17 -15.65
11 18 26.59
12 20 33.10
13 22 28.03
14 23 -30.07
15 25 93.77
16 27 -25.85
17 29 48.12
18 30 -34.37
19 32 50.75

L1 1st lens group L2 2nd lens group L3 3rd lens group L4 4th lens group L5 5th lens group L6 6th lens group L7 7th lens group DOE Diffraction surface

Claims (8)

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 rear group including one or more lens groups, and an interval between adjacent lens groups during zooming Is a zoom lens that changes
The first lens group has a diffractive surface;
When the focal length of the entire system at the telephoto end is ft, the focal length of the first lens group is f1, the focal length of the diffractive surface is fdoe, and the total lens length at the telephoto end is Lt,
0.2 <f1 / ft <0.4
0.40 <Lt / ft <0.68
10.0 <fdoe / f1 <400.0
A zoom lens satisfying the following conditional expression:   The rear group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens having a negative refractive power. The zoom lens according to claim 1, wherein the zoom lens includes a seventh lens group having a positive refractive power.   The rear group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens having a negative refractive power. And a seventh lens group having a positive refractive power, and the first lens group, the third lens group, the fourth lens group, and the sixth lens group move along different paths during zooming. The zoom lens according to claim 1. When the focal length of the second lens group is f2,
−6.0 <f1 / f2 <−3.5
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The rear group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens having a negative refractive power. A seventh lens group having a positive refractive power,
When the focal length of the third lens group is f3,
2.0 <f1 / f3 <4.5
5. The zoom lens according to claim 1, wherein the following conditional expression is satisfied. The rear group includes, in order from the object side to the image side, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, a fifth lens group having a positive refractive power, and a sixth lens having a negative refractive power. A seventh lens group having a positive refractive power,
When the focal length of the fourth lens group is f4,
−4.5 <f1 / f4 <−2.0
The zoom lens according to claim 1, wherein the following conditional expression is satisfied. When the distance along the optical axis from the lens surface closest to the object side of the first lens group to the lens surface closest to the image side of the first lens group is Lg1,
0.05 <Lg1 / f1 <0.25
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.   An image pickup apparatus comprising the zoom lens according to claim 1.