Patent Grant
11137586
The present invention relates to a zoom lens and an image pickup apparatus.
In recent years, there has been a demand that an image pickup apparatus such as a television camera, a movie camera, or a photography camera be equipped with a zoom lens with a wide angle of view, a high zoom ratio, and high optical performance. In particular, an image pickup device, such as a CCD or CMOS sensor, used in a television or movie camera as a professional video shooting system has a substantially even resolution over the entire image pickup range. For this reason, a zoom lens using such an image pickup device is desired to have a substantially even resolution from the center to the periphery of the field.
A positive lead type zoom lens including, in order from the object side, a first lens unit having a positive refractive power and a second lens unit for zooming having a negative refractive power is known as a zoom lens with a wide angle of view and a high zoom ratio. Japanese Patent Application Laid-Open No. 2012-220901 discloses a zoom lens with a zoom ratio of 90 to 120, the zoom lens including, in order from the object side, a first lens unit having a positive refractive power and a second lens unit having a negative refractive power, the first lens unit consisting of six lenses. Further, Japanese Patent Application Laid-Open No. 2016-71140 discloses a zoom lens having a zoom ratio of approximately 20× and including, in order from the object side, a first lens unit having a positive refractive power and a second lens unit having a negative refractive power, the first lens unit consisting of six lenses.
In order for a positive lead type zoom lens with the above-described configuration to achieve high optical performance, a wide angle of view, and reduction in size at the same time, it is important to set the lens configuration, refractive power, and glass material of the first lens unit appropriately. When a wider angle of view, a higher magnification, and a smaller size are to be achieved at the same time, chromatic aberration at the telephoto end in particular is under-corrected, making it difficult to achieve favorable optical performance from the center to the periphery of the field.
The refractive powers and glass materials of the lenses in the first lens unit of the zoom lens disclosed in Japanese Patent Application Laid-Open No. 2012-220901 tend to under-correct chromatic aberration at the telephoto end when the zoom lens is designed to achieve a wider angle of view and a higher magnification. Further, the zoom lens disclosed in Japanese Patent Application Laid-Open No. 2016-71140 has a zoom ratio of approximately 20, and the refractive powers and glass materials used for the lenses in the first lens unit of this zoom lens are not optimal for a zoom lens with a zoom ratio of higher than 40.
The disclosure provides, for example, a zoom lens advantageous in a wide angle of view, a high zoom ratio, small size and weight, and high optical performance over an entire zoom range.
A zoom lens of the present invention is a zoom lens consisting of, in order from an object side to an image side, a first lens unit having a positive refractive power and configured not to be moved for zooming, a second lens unit having a negative refractive power and configured to be moved for zooming, and a rear lens group including at least one lens unit, wherein the first lens unit includes at least six lenses, a lens closest to the object side included in the first lens unit is a negative lens, and the zoom lens satisfies conditional expressions
−1.65<f1n/f1<−1.10,
37<ν1n<48, and
87<νpave<100,
where f1n is a focal length of the negative lens, ν1n is an Abbe number of the negative lens with respect to d-line, f1 is a focal length of the first lens unit, and νpave is an average of Abbe numbers of positive lenses included in the first lens unit with respect to d-line, the Abbe number νd with respect to d-line being expressed by an expression
νd=(Nd−1)/(NF−NC),
where NF is a refractive index with respect to F-line, NC is a refractive index with respect to C-line, and Nd is a refractive index with respect to d-line.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Preferred embodiments of the present invention are described in detail below based on the accompanying drawings.
First, the characteristics of a zoom lens of the present invention are described using conditional expressions. The zoom lens of the present invention defines the lens configuration, refractive power, and glass material of a first lens unit in order to achieve a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens of the present invention, as well as an image pickup apparatus having the same, includes, in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a rear lens group including at least one lens unit. The first lens unit is not configured to be moved for zooming. The second lens unit is configured to be move for zooming. The first lens unit includes at least six lenses, and the lens closest to the object side in the first lens unit is a 1n lens having a negative refractive power. The zoom lens satisfies the following conditional expressions:
−1.65<f1n/f1<−1.10, and (1)
37<ν1n<48, (2)
where f1n is the focal length of the 1n lens, ν1n is the Abbe number for d-line of the 1n lens, and f1 is the focal length of the first lens unit. Optical effects achieved by the above configuration of the first lens unit of the present invention are described. First, the first lens unit of the present invention has the 1n lens having a negative refractive power at a position closest to the object side.
In addition, Expression (1) defines the ratio of the focal length of 1n lens, which is the lens closest to the object side in the first lens unit, to the focal length of the first lens unit. Expression (2) defines the Abbe number of the 1n lens, which is the lens closest to the object side in the first lens unit. The conditions in Expressions (1) and (2) are defined to favorably correct chromatic aberration at the telephoto end while allowing the zoom lens to achieve a wide angle of view, a high magnification, and reduction in size. If the upper limit of Expression (1) is not satisfied, a refractive power of the 1n lens is too strong relative to the first lens unit. Then, the high-order spherical aberration at the telephoto end increases, making it difficult to achieve favorable optical performance. Conversely, if the lower limit of Expression (1) is not satisfied, a refractive power of the 1n lens is too weak relative to the first lens unit. Then, the above-described size reduction effect for the 1n lens is not sufficiently produced, making it difficult to reduce the size of the zoom lens. Moreover, when the 1n lens has a weak refractive power, chromatic aberration caused by the positive lenses in the first lens unit cannot be corrected sufficiently, thus causing under-correction of the chromatic aberration at the telephoto end. If the upper limit of Expression (2) is not satisfied, the difference in Abbe number between the positive and negative lenses in the first lens unit is too small, making the refractive powers of the lenses in the first lens unit too strong. As a result, the high-order spherical aberration at the telephoto end increases, making it difficult to achieve favorable optical performance. Conversely, if the lower limit of Expression (2) is not satisfied, the difference in Abbe number between the positive and negative lenses in the first lens unit is too large, weakening the refractive power of the 1n lens. Then, chromatic aberration caused by the positive lenses in the first lens unit is not sufficiently corrected, thus causing under-correction of chromatic aberration at the telephoto end. It is more preferable when Expression (1) is set as follows:
−1.63<f1n/f1<−1.15. (1a)
As another aspect, the zoom lens of the present invention is characterized in that the first lens unit consists of, in order from the object side to the image side, a 1-1 lens subunit configured not to be moved for focusing and a 1-2 lens subunit configured to be moved for focusing. When the first lens unit is thus provided with a lens unit configured to be moved for focusing, the distance by which the 1-2 lens subunit moves for focusing can be made constant over the entire zoom range.
As another aspect of the zoom lens of the present invention, the Abbe number of the positive lenses in the first lens unit is defined. Specifically, the zoom lens of the present invention satisfies the following conditional expression:
80<νpave<100, (3)
where νpave is the average of Abbe numbers for d-line of the positive lenses in the first lens unit. The condition in Expression (3) is defined in order to correct axial chromatic aberration at the telephoto end and to achieve high optical performance. If the upper limit of Expression (3) is not satisfied, it is difficult to produce a glass material with low dispersion. Conversely, if the lower limit of Expression (3) is not satisfied, the difference in Abbe number between the positive and negative lenses in the first lens unit is too small, making the refractive powers of the lenses in the first lens unit too strong. As a result, the high-order spherical aberration at the telephoto end increases, making it difficult to achieve favorable optical performance. It is more preferable when Expression (3) is set as follows:
87<νpave<97. (3a)
As another aspect of the zoom lens of the present invention, the partial dispersion ratio of an optical material used in the first lens unit is defined. The zoom lens satisfies the following conditional expression:
−9.0×10−4<(θpave−θnave)/(νpave−νnave)<−3.0×10−4, (4)
where νpave is the average of the Abbe numbers for d-line of the positive lenses in the first lens unit, νnave is the average of the Abbe numbers for d-line of the negative lenses in the first lens unit, θpave is the average of the partial dispersion ratios of the positive lenses in the first lens unit, and θnave is the average of the partial dispersion ratios of the negative lenses in the first lens unit.
The Abbe number and partial dispersion ratio of a material of an optical element (lens) used in the present invention are as follows. When Ng, NF, Nd, and NC are the indices of refraction at the Fraunhofer g-line (435.8 nm), the Fraunhofer F-line (486.1 nm), the Fraunhofer d-line (587.6 nm), and the Fraunhofer C-line (656.3 nm), respectively, the Abbe number νd and the partial dispersion ratio θgF for g-line and F-line are as follows:
νd=(Nd−1)/(NF−NC), and (a)
θgF=(Ng−NF)/(NF−NC). (b)
Regarding existing optical materials, the partial dispersion ratio θgF is within a narrow range relative to the Abbe number νd. Further, there is a tendency that the smaller the Abbe number νd, the larger the partial dispersion ratio θgF, and the larger the Abbe number νd, the lower the index of refraction. A condition for correcting chromatic aberration of a thin, closely-attached system consisting of two lenses 1 and 2 respectively having refractive powers φ1, φ2 and Abbe number ν1, ν2 and a refractive power φ1 and an Abbe number ν1 is expressed as
φ1/ν1+φ2/ν2=E. (c)
The combined refractive power φ of the lens 1 and the lens 2 is found by
φ=φ1+φ2. (d)
When E=0 in Expression (c), the image formation position for C-line and the image formation for F-line coincide with respect to chromatic aberration. Then, φ1 and φ2 are expressed by the following expressions:
φ1=φ×ν1/(ν1−ν2), and (e)
φ2=φ×ν2/(ν1−ν2). (f)
ΔS=−(1/φ)×(θ1−θ2)/(ν1−ν2). (g)
In order to favorably correct the secondary spectrum of axial chromatic aberration at the telephoto end, the amount of secondary spectrum caused by the first lens unit needs to be adjusted since it is the first lens unit that noticeably causes the secondary spectrum. The first lens unit has a positive refractive power, and in order to favorably correct the secondary spectrum of axial chromatic aberration at the telephoto end, a glass material selected for the first lens unit needs to be a material that causes only a small secondary spectrum amount ΔS.
The condition in Expression (4) is defined in order to correct axial chromatic aberration at the telephoto end and to achieve high optical performance. If the upper limit of Expression (4) is not satisfied, the secondary spectrum of axial chromatic aberration at the telephoto end is advantageously corrected, but the difference in Abbe number between the positive and negative lenses in the first lens unit is small, making the refractive powers of the lenses in the first lens unit strong. As a result, high-order spherical aberration at the telephoto end increases, making it difficult to achieve favorable optical performance. Conversely, if the lower limit of Expression (4) is not satisfied, the secondary spectrum of axial chromatic aberration at the telephoto end increases, making it difficult to favorably correct chromatic aberration at the telephoto end. It is more preferable when Expression (4) is set as follows:
−8.0×10−4<(θpave−θnave)/(νpave−νnave)<−3.5×10−4. (4a)
As another aspect, the zoom lens of the present invention is characterized in that, the 1-1 lens subunit includes, in order from the object side to the image side, the 1n lens having a negative refractive power, a 2p lens having a positive refractive power, and a 3p lens having a positive refractive power. When the 1-1 lens subunit thus includes the negative lens on the object side and the positive lenses on the image side to form a retrofocus configuration, the entrance pupil of the zoom lens can be shifted to the object side while the image-side principal point of the first lens unit is shifted to the image side. Thus, such a configuration can advantageously reduce the size of the zoom lens by preventing the lens diameter of the 1-1 lens subunit from being increased by widening of the angle of view.
As another aspect, the zoom lens of the present invention is characterized in that the 1n lens is a biconcave lens. This makes it possible to set an appropriate refractive power for the 1n lens without making the radius of curvature of the 1n lens on the image side too small. When the radius of curvature of the 1n lens on the image side is small, the air interval between the 1n lens and the 2p lens becomes sensitive to the spherical aberration at the telephoto end, and hence, the zoom lens tends to be susceptible to manufacture error in lens thickness or the like.
As another aspect of the zoom lens of the present invention, the refractive powers of the lenses in the first lens unit are defined. The zoom lens satisfies the following conditional expressions:
−0.9<f1n/f2p<−0.3, and (5)
−0.80<f1n/f3p<−0.15, (6)
where f1n, f2p, and f3p are the focal lengths of the 1n lens, the 2p lens, and the 3p lens, respectively. Expressions (5) and (6) are defined in order to reduce the size of the zoom lens and to achieve high optical performance at the telephoto end. If the upper limit of Expression (5) is not satisfied, the refractive power of the 2p lens is weak. Then, the radius of curvature of the 1n lens on the image side and the radius of curvature of the 2p lens on the object side increase, causing under-correction of the spherical aberration at the telephoto end. Conversely, if the lower limit of Expression (5) is not satisfied, a refractive power of the 1n lens is too weak relative to the 2p lens. Then, it is difficult to prevent the lens diameter of the 1n lens from being increased by widening of the angle of view. If the upper limit of Expression (6) is not satisfied, the refractive power of the 3p lens is weak, and consequently, the refractive power of the 2p lens is strong. Thus, the radius of curvature of the 1n lens on the image side and the radius of curvature of the 2p lens on the object side decrease, making it difficult to correct the high-order spherical aberration at the telephoto end. Conversely, if the lower limit of Expression (6) is not satisfied, a refractive power of the 1n lens is too weak relative to the 3p lens. Thus, it is difficult to prevent the lens diameter of the 1n lens from being increased by widening of the angle of view. It is more preferable when Expressions (5) and (6) are set as follows:
−0.8<f1n/f2p<−0.4, and (5a)
−0.60<f1n/f3p<−0.20. (6a)
As another aspect of the zoom lens of the present invention, the ratio of the focal length of the zoom lens at the telephoto end to the focal length of the first lens unit is defined. The zoom lens satisfies the following conditional expression:
2.0<ft/f1<6.0, (7)
where f1 is the focal length of the first lens unit, and ft is the focal length of the zoom lens at the telephoto end. The condition in Expression (7) is defined in order to favorably correct axial chromatic aberration while achieving a high magnification. If the upper limit of Expression (7) is not satisfied, the size of the zoom lens is advantageously reduced, but it is difficult to achieve high performance at the telephoto end and to favorably correct axial chromatic aberration in particular. Conversely, if the lower limit of Expression (7) is not satisfied, the focal length of the first lens unit increases, making it difficult to achieve a high magnification and size reduction of the zoom lens at the same time. It is more preferable when Expression (7) is set as follows:
2.3<ft/f1<5.0. (7a)
Further, the image pickup apparatus of the present invention includes a zoom lens of any of the embodiments and a solid-state image pickup element having a predetermined effective image pickup range to receive an image formed by the zoom lens.
Note that a protective filter or a lens equivalent to a protective filter may be attached to the first lens unit of the present invention at a position closest to the object side. If a protective filter or a lens equivalent to a protective filter satisfies the following conditional expression
|f1/ff|<1.0×10−4 (8)
where ff is the focal length of the protective filter or the lens equivalent to the protective filter, the protective filter or lens equivalent thereto is not included in the first lens unit.
Specific configurations of the zoom lens of the present invention are described below by reciting the characteristics of the lens configurations of Numerical Embodiments 1 to 8 corresponding to Embodiments 1 to 8.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fourth lens unit L4 and the fifth lens unit L5 and configured not to be moved in the optical-axis direction for zooming. “P” denotes a glass block representing a color separation prism or an optical filter. “I” denotes an image plane. When the zoom lens is used as an image pickup optical system for a broadcasting television camera, a video camera, or a digital still camera, the image plane I corresponds to the imaging plane of a solid-state image pickup element (a photo-electric conversion element) or the like that receives an optical image formed by the zoom lens and performs photo-electric conversion. When the zoom lens is used as an image pickup optical system for a film camera, the image plane I corresponds to a film plane that is sensitive to an optical image formed by the zoom lens.
In the section for spherical aberration in each longitudinal aberration diagram, the solid line, the dot-dot-dash line, the dot-dash line, and the broken line denote the e-line, the g-line, the C-line, and the F-line, respectively. In the section for astigmatism, the broken line and the solid line denote the meridional image plane and the sagittal image plane, respectively. In the section for chromatic aberration of magnification, the dot-dot-dash line, the dot-dash line, and the broken line denote the g-line, the C-line, and the F-line, respectively. Further, “ω” denotes a half angle of view, and “Fno” denotes an f-number. In each longitudinal aberration diagram, spherical aberration is depicted on a scale of ±0.4 mm; astigmatism, on a scale of ±0.4 mm; distortion, on a scale of ±10%; and chromatic aberration of magnification, on a scale of ±0.1 mm. Note that in the following embodiments, the wide angle end and the telephoto end refer to zoom positions which are available ends of the zoom range in which the second lens unit L2 for zooming can move on the optical axis mechanically.
The first lens unit L1 corresponds to the 1st to 12th surfaces. The second lens unit L2 corresponds to the 13th to 19th surfaces, the third lens unit L3 corresponds to the 20th to 25th surfaces, and the fourth lens unit L4 corresponds to the 26th to 30th surfaces. The fifth lens unit L5 corresponds to the 31st to 53rd surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 6th surfaces, and the 1-2 lens subunit L12 corresponds to the 7th to 12th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Numerical Embodiment 1 corresponding to Embodiment 1 above is described. Not only in Numerical Embodiment 1 but also in the following embodiments, “i” indicates the ordinal number of a surface (optical surface) from the object side; “ri”, the radius of curvature of the i-th surface from the object side; “di”, the distance (on the optical axis) between the i-th surface and the (i+1)-th surface from the object side; “ndi”, “νdi”, and “θgFi”, the refractive index, the Abbe number, and the partial dispersion ratio, respectively, of a medium (optical member) between the i-th surface and the (i+1)-th surface from the object side; and “BF”, a back focal length in air. With an X axis being the optical-axis direction, an H axis being perpendicular to the optical axis, a light travelling direction being positive, “R” being a paraxial radius of curvature, “k” being a conic constant, and “A3” to “A16” each being an aspherical coefficient, an aspherical shape is expressed as follows. Note that “E-Z” in aspherical surface data indicates “×10−Z”.
Table 1 shows values corresponding to the conditional expressions of Embodiment 1. Embodiment 1 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens of Embodiment 1 achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range. It should be noted that the zoom lens of the present invention has to satisfy Expressions (1) and (2), but does not necessarily have to satisfy Expressions (3) to (7). However, better effects can be produced when at least one of Expressions (3) to (7) is additionally satisfied. This is true to the other embodiments as well.
An image pickup apparatus offering high optical performance can be obtained when the zoom lens of the present invention is thus applied to a television camera.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fourth lens unit L4 and the fifth lens unit L5 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 12th surfaces. The second lens unit L2 corresponds to the 13th to 19th surfaces, the third lens unit L3 corresponds to the 20th to 25th surfaces, and the fourth lens unit L4 corresponds to the 26th to 30th surfaces. The fifth lens unit L5 corresponds to the 31st to 43rd surfaces, and the sixth lens unit L6 corresponds to the 44th to 53rd surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 6th surfaces, and the 1-2 lens subunit L12 corresponds to the 7th to 12th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 2. Embodiment 2 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fourth lens unit L4 and the fifth lens unit L5 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 3rd to 14th surfaces. The second lens unit L2 corresponds to the 15th to 21st surfaces, the third lens unit L3 corresponds to the 22nd to 28th surfaces, and the fourth lens unit L4 corresponds to the 29th to 32nd surfaces. The fifth lens unit L5 corresponds to the 34th to 55th surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 3rd to 8th surfaces, and the 1-2 lens subunit L12 corresponds to the 9th to 14th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 3. Embodiment 3 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fourth lens unit L4 and the fifth lens unit L5 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 12th surfaces. The second lens unit L2 corresponds to the 13th to 19th surfaces, the third lens unit L3 corresponds to the 20th to 25th surfaces, and the fourth lens unit L4 corresponds to the 26th to 28th surfaces. The fifth lens unit L5 corresponds to the 30th to 51st surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 6th surfaces, and the 1-2 lens subunit L12 corresponds to the 7th to 12th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 4. Embodiment 4 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fourth lens unit L4 and the fifth lens unit L5 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 12th surfaces. The second lens unit L2 corresponds to the 13th to 22nd surfaces, the third lens unit L3 corresponds to the 23rd to 24th surfaces, and the fourth lens unit L4 corresponds to the 25th to 31st surfaces. The fifth lens unit L5 corresponds to the 33rd to 55th surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 6th surfaces, and the 1-2 lens subunit L12 corresponds to the 7th to 12th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 5. Embodiment 5 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fifth lens unit L5 and the sixth lens unit L6 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 14th surfaces. The second lens unit L2 corresponds to the 15th to 16th surfaces, the third lens unit L3 corresponds to the 17th to 21st surfaces, and the fourth lens unit L4 corresponds to the 22nd to 23rd surfaces. The fifth lens unit L5 corresponds to the 24th to 32nd surfaces, and the sixth lens unit L6 corresponds to the 34th to 55th surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 8th surfaces, and the 1-2 lens subunit L12 corresponds to the 9th to 14th surfaces. The first lens unit L1 consists of seven lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a biconcave lens, a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 6. Embodiment 6 satisfies Expressions (1) to (5) and (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2, the third lens unit L3, the fourth lens unit L4, and the fifth lens unit L5 form the zooming system. “SP” denotes an aperture stop, which is disposed between the fifth lens unit L5 and the sixth lens unit L6 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 13th surfaces. The second lens unit L2 corresponds to the 14th to 19th surfaces, the third lens unit L3 corresponds to the 20th to 21st surfaces, and the fourth lens unit L4 corresponds to the 22nd to 24th surfaces. The fifth lens unit L5 corresponds to the 25th to 28th surfaces, and the sixth lens unit L6 corresponds to the 30th to 45th surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 7th surfaces, and the 1-2 lens subunit L12 corresponds to the 8th to 13th surfaces. The first lens unit L1 consists of seven lenses which are, in order from the object side, a biconcave lens, a cemented lens formed by a meniscus concave lens having a convex surface facing the object side and a biconvex lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 7. Embodiment 7 satisfies Expressions (1) to (4), (6), and (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
The zoom lens in
In this embodiment, the second lens unit L2 and the third lens unit L3 form the zooming system. “SP” denotes an aperture stop, which is disposed between the third lens unit L3 and the fourth lens unit L4 and configured not to be moved in the optical-axis direction for zooming.
The first lens unit L1 corresponds to the 1st to 12th surfaces. The second lens unit L2 corresponds to the 13th to 19th surfaces, the third lens unit L3 corresponds to the 20th to 28th surfaces, and the fourth lens unit L4 corresponds to the 30th to 56th surfaces. The first lens unit L1 consists of a 1-1 lens subunit L11 configured not to be moved for focusing and a 1-2 lens subunit L12 having a positive refractive power configured to be moved for focusing from infinity to close-up. The 1-1 lens subunit L11 corresponds to the 1st to 6th surfaces, and the 1-2 lens subunit L12 corresponds to the 7th to 12th surfaces. The first lens unit L1 consists of six lenses which are, in order from the object side, a biconcave lens, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, a biconvex lens, a meniscus convex lens having a concave surface facing the image side, and a meniscus convex lens having a concave surface facing the image side.
Table 1 shows values corresponding to the conditional expressions of Embodiment 8. Embodiment 8 satisfies Expressions (1) to (7) to appropriately set the lens configuration, refractive power, and glass material of the first lens unit. Thereby, the zoom lens achieves a wide angle of view, a high zoom ratio, reduction in size and weight, and high optical performance over the entire zoom range.
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to those embodiments and is variously modifiable and changeable within the gist thereof. The present invention is characterized by the appropriate setting of the lens configuration, refractive power, and glass material of the first lens unit, and the advantageous effects can be still produced when the rear lens group, which corresponds to lens units on the image side of the second lens unit, has a configuration other than those described in Numerical Embodiments 1 to 8.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2018-034959, filed Feb. 28, 2018, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2018-034959 | Feb 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 9264638 | Nakamura et al. | Feb 2016 | B2 |
| 9268120 | Shimomura et al. | Feb 2016 | B2 |
| 9310592 | Wakazono et al. | Apr 2016 | B2 |
| 9329372 | Shimomura | May 2016 | B2 |
| 9400374 | Yoshimi et al. | Jul 2016 | B2 |
| 9678318 | Nakamura et al. | Jun 2017 | B2 |
| 9716829 | Shimomura | Jul 2017 | B2 |
| 9904043 | Shimomura et al. | Feb 2018 | B2 |
| 20140029112 | Sanjo | Jan 2014 | A1 |
| 20140104467 | Takemoto | Apr 2014 | A1 |
| 20170108676 | Hori | Apr 2017 | A1 |
| 20170108678 | Miyazawa et al. | Apr 2017 | A1 |
| 20180224640 | Shimomura | Aug 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 2698660 | Feb 2014 | EP |
| 2012220901 | Nov 2012 | JP |
| 2016071140 | May 2016 | JP |
| 2017062303 | Mar 2017 | JP |
| Entry |
|---|
| Extended European Search Report issued by the European Patent Office dated Jul. 1, 2019 corresponding to European Patent Application No. 19158451.5. |
| Notice of the First Office Action dated May 31, 2021 by the National Intellectual Property Administration of the People's Republic of China in corresponding CN Patent Application No. 201910149244.9, with English translation. |
| Number | Date | Country | |
|---|---|---|---|
| 20190265451 A1 | Aug 2019 | US |
