Zoom lens and imaging device

Abstract

The present invention has a positive first lens group, a positive second lens group, and a negative third lens group that are disposed in that order from the object side to the image side. The first lens group is fixed when varying magnification, and the second and third lens groups are moved when varying magnification. The first lens group is constituted by four or fewer lenses, thereby satisfying the following conditional equations (1) and (2). (1) 1.00<f2 / f1<11.00 (2) 0.57<m2 / m3<0.95, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, m2 is the amount of movement of the second lens group when varying magnification from the wide-angle end to the telephoto end, and m3 is the amount of movement of the third lens group when varying magnification from the wide-angle end to the telephoto end.

Description

Technical Field

[0001] The present technology relates to the technical field of zoom lenses having a plurality of lens groups and imaging devices using such zoom lenses.

Background Art

[0002] For imaging optical systems used in imaging devices such as still cameras and video cameras, optical systems with various focal lengths and apertures are desired according to the application. For example, for a telephoto zoom lens that can enlarge a distant subject with a desired angle of view, high image quality, small size and light weight, and the ability to perform rapid focusing with a high zoom ratio are required.

[0003] As a zoom lens that satisfies these requirements, a positive lead type zoom lens in which a lens group having a positive refractive power on the object side is arranged is known (see, for example, Patent Document 1 and Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] However, for high image quality of a telephoto zoom lens, correction of chromatic aberration such as axial chromatic aberration and lateral chromatic aberration becomes important.

[0006] As the most effective method for correcting chromatic aberration, there is a method of using an anomalous partial dispersion glass in the group located closest to the object side that passes through a position where both the axial light beam diameter and the off-axis light beam diameter are high, and utilizing it for chromatic aberration correction.

[0007] On the one hand, in order to improve the image quality of a telephoto zoom lens, it is also important to correct spherical aberration and coma aberration well. However, anomalous partial dispersion glass tends to have a low refractive index. Therefore, a large number of lens elements are required for aberration correction, and an increase in the number of lens elements may lead to an increase in weight.

[0008] Therefore, an object of the present zoom lens and imaging device is to provide a zoom lens that corrects various aberrations well while being lightweight, and an imaging device equipped with the same.

Means for Solving the Problems

[0009] The zoom lens according to the present technology has six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side. The interval between adjacent lens groups changes during zooming. The first lens group is fixed during zooming, and the second lens group and the third lens group are moved during zooming. The first lens group is composed of 4 or fewer lenses, and satisfies the following conditional expressions (1) and (2A). and conditional expression (4) It satisfies the following. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (4) 0.35 < f1 / ft < 1.20 However, f1: Focal length of the first lens group f2: Focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end ft: Overall focal length at the telephoto end Let them be.

[0010] As a result, the combined refractive power of the first lens group and the second lens group increases, and the refractive power of the first lens group is optimized. Also, the diameter of the light beam incident on the second lens group at the telephoto end becomes smaller, and the reduction effect during zooming by the second lens group is suppressed.

[0019] The imaging device according to the present technology includes a zoom lens and an imaging element that converts an optical image formed by the zoom lens into an electrical signal. The zoom lens has six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side. During zooming, the distance between adjacent lens groups changes. The first lens group is fixed during zooming, and the second lens group and the third lens group are moved during zooming. The first lens group is composed of 4 or fewer lenses, and satisfies the following conditional expressions (1) and (2A). and conditional expression (4) It satisfies the following. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (4) 0.35 < f1 / ft < 1.20 However,[[]] f1: Focal length of the first lens group f2: Focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end ft: Overall focal length at the telephoto end Let them be.

[0020] As a result, in the zoom lens, the combined refractive power of the first lens group and the second lens group increases, and the refractive power of the first lens group is optimized. Also, the diameter of the light beam incident on the second lens group at the telephoto end decreases, and the reduction effect during zooming by the second lens group is suppressed.

Brief Description of the Drawings

[0021]

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Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments for implementing the present technology zoom lens and imaging device will be described.

[0023] [Configuration of Zoom Lens] The present technology zoom lens has a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side. The first lens group is fixed during zooming, and the second lens group and the third lens group are moved during zooming. The first lens group is composed of 4 or fewer lenses and satisfies the following conditional expressions (1) and (2). (1) 1.00 < f2 / f1 < 11.00 (2) 0.57 < m2 / m3 < 0.95 However, f1: Focal length of the first lens group f2: Focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end Let it be.

[0024] As described above, having a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, with the first lens group being composed of 4 or fewer lenses and fixed during zooming, and the second lens group and the third lens group being moved during zooming, it becomes possible to reduce the weight of the optical system. Also, although the first lens group has a small number of lenses, by making the second lens group a positive lens group, the total refractive power of the first lens group and the second lens group is increased and good aberration correction can be achieved.

[0025] Conditional expression (1) is an expression for achieving weight reduction while performing good aberration correction of the optical system, and is a conditional expression for optimizing the focal length of the first lens group and the focal length of the second lens group.

[0026] If it is below the lower limit value of conditional expression (1), the refractive power of the first lens group weakens and the diameter of the light beam incident on the second lens group increases, making it difficult to reduce the diameter of the optical system.

[0027] On the other hand, when exceeding the upper limit value of conditional expression (1), the refractive power of the first lens group increases, making it difficult to correct various aberrations, particularly spherical aberration, axial chromatic aberration, and magnification chromatic aberration.

[0028] Therefore, by satisfying conditional expression (1), the refractive power of the first lens group is optimized, the diameter of the optical system can be reduced, and various aberrations, particularly spherical aberration, axial chromatic aberration, and magnification chromatic aberration, can be corrected well.

[0029] In addition, it is possible to set the range of conditional expression (1) to the range of the following conditional expression (1A). (1A) 1.08 < f2 / f1 < 10.10 By setting the range of conditional expression (1) to the range of conditional expression (1A), the above-described effects can be further enhanced.

[0030] Also, it is possible to set the range of conditional expression (1) to the range of the following conditional expression (1B). (1B) 1.08 < f2 / f1 < 8.0 By setting the range of conditional expression (1) to the range of conditional expression (1B), the above-described effects can be enhanced even more.

[0031] Furthermore, it is possible to set the range of conditional expression (1) to the range of the following conditional expression (1C). (1C) 1.08 < f2 / f1 < 6.0 By setting the range of conditional expression (1) to the range of conditional expression (1C), the above-described effects can be enhanced even further.

[0032] Moreover, it is possible to set the range of conditional expression (1) to the range of the following conditional expression (1D). (1D) 1.08 < f2 / f1 < 4.0 By setting the range of conditional expression (1) to the range of conditional expression (1D), the above-described effects can be enhanced even more significantly.

[0033] In addition, it is possible to set the range of conditional expression (1) to the range of the following conditional expression (1E). (1E) 1.08 < f2 / f1 < 2.5 By setting the range of conditional expression (1) to the range of conditional expression (1E), the above-described effects can be further enhanced even more.

[0034] Conditional expression (2) is a conditional expression for relatively defining the movement amount of the second lens group and the movement amount of the third lens group.

[0035] If it is below the lower limit value of conditional expression (2), the diameter of the light beam incident on the second lens group at the telephoto end becomes large, making it difficult to reduce the diameter of the optical system.

[0036] On the other hand, if it exceeds the upper limit value of conditional expression (2), the reduction effect during zooming by the second lens group becomes large, making it difficult to achieve high magnification.

[0037] Therefore, when the zoom lens satisfies conditional expression (2), the diameter of the light beam incident on the second lens group at the telephoto end becomes small and the reduction effect during zooming by the second lens group is suppressed. Thus, it is possible to reduce the diameter of the optical system and achieve high magnification.

[0038] Incidentally, it is possible to set the range of conditional expression (2) to the range of the following conditional expression (2A). (2A) 0.59 < m2 / m3 < 0.94 By setting the range of conditional expression (2) to the range of conditional expression (2A), the above-described effects can be further enhanced.

[0039] As described above, according to the zoom lens of the present technology, it is possible to provide a zoom lens that is lightweight and corrects various aberrations well.

[0040] [Configuration of Zoom Lens According to One Embodiment] In the zoom lens according to one embodiment of the present technology, it is desirable to satisfy the following conditional expression (3). (3) - 5.0 < f1 / f23w < -1.0 However, f23w: The combined focal length at the wide-angle end of the second lens group and the third lens group shall be.

[0041] The conditional expression (3) is a conditional expression for relatively defining the focal length of the first lens group with respect to the combined focal length of the second lens group and the third lens group.

[0042] If it is below the lower limit value of the conditional expression (3), the refractive power of the first lens group becomes too strong, making it difficult to correct various aberrations at the telephoto end, especially spherical aberration, axial chromatic aberration, and lateral chromatic aberration.

[0043] On the other hand, if it exceeds the upper limit value of the conditional expression (3), the refractive power of the first lens group becomes too weak, increasing the diameter of the light rays incident on the second lens group at the telephoto end and making it difficult to reduce the size of the optical system.

[0044] Therefore, by satisfying the conditional expression (3), the refractive power of the first lens group is optimized, enabling good correction of various aberrations at the telephoto end, especially spherical aberration, axial chromatic aberration, and lateral chromatic aberration, and reducing the size of the optical system.

[0045] In addition, it is possible to set the range of the conditional expression (3) to the range of the following conditional expression (3A). (3A) - 4.2 < f1 / f23w < -2.5 By setting the range of the conditional expression (3) to the range of the conditional expression (3A), the above-described effects can be further enhanced.

[0046] In the zoom lens according to an embodiment of the present technology, it is desirable to satisfy the following conditional expression (4). (4) 0.35 < f1 / ft < 1.20 However, ft: The focal length of the entire system at the telephoto end shall be.

[0047] Conditional expression (4) is a conditional expression for defining the focal length of the first lens group relative to the focal length of the optical system at the telephoto end.

[0048] If it is below the lower limit value of conditional expression (4), the refractive power of the first lens group becomes too strong, making it difficult to correct various aberrations at the telephoto end, particularly spherical aberration, axial chromatic aberration, and lateral chromatic aberration.

[0049] On the other hand, if it exceeds the upper limit value of conditional expression (4), the refractive power of the first lens group becomes too weak, increasing the diameter of the light beam incident on the second lens group at the telephoto end and making it difficult to reduce the size of the optical system.

[0050] Therefore, when the zoom lens satisfies conditional expression (4), the refractive power of the first lens group is optimized, enabling good correction of various aberrations at the telephoto end, particularly spherical aberration, axial chromatic aberration, and lateral chromatic aberration, and reducing the size of the optical system.

[0051] Incidentally, it is possible to set the range of conditional expression (4) within the range of the following conditional expression (4A). (4A) 0.45 < f1 / ft < 0.85 By setting the range of conditional expression (4) within the range of conditional expression (4A), the above-described effects can be further enhanced.

[0052] In the zoom lens according to an embodiment of the present technology, it is desirable to satisfy the following conditional expression (5). (5) 2.1 < d1t / d2t < 9.9 However, d1t: The distance between the first lens group and the second lens group at the telephoto end d2t: The distance between the second lens group and the third lens group at the telephoto end shall be as follows.

[0053] Conditional expression (5) is a conditional expression for relatively defining the movement amount of the second lens group and the movement amount of the third lens group.

[0054] If it is less than the lower limit value of conditional expression (5), the diameter of the light beam incident on the second lens group at the telephoto end becomes large, making it difficult to reduce the size of the optical system.

[0055] On the other hand, if it exceeds the upper limit value of conditional expression (5), the reduction effect during zooming by the second lens group becomes large, making it difficult to achieve a high magnification.

[0056] Therefore, when the zoom lens satisfies conditional expression (5), the diameter of the light beam incident on the second lens group at the telephoto end becomes small and the reduction effect during zooming by the second lens group is suppressed. Thus, it is possible to reduce the size of the optical system and achieve a high magnification.

[0057] In addition, it is possible to set the range of conditional expression (5) to the range of the following conditional expression (5A). (5A) 3.0 < d1t / d2t < 7.0 By setting the range of conditional expression (5) to the range of conditional expression (5A), the above-described effects can be further enhanced.

[0058] In the zoom lens according to an embodiment of the present technology, it is desirable to perform focusing by moving all or a part of the group located on the image side with respect to the third lens group in the optical axis direction.

[0059] By moving all or a part of the group located on the image side with respect to the third lens group in the optical axis direction, focusing is performed by a group or a part thereof having a small volume and a small weight with respect to the entire system. Therefore, it is possible to speed up the focus drive.

[0060] [Numerical Examples of Zoom Lenses] Hereinafter, specific embodiments of the zoom lens of the present technology and numerical examples in which specific numerical values are applied to the embodiments will be described with reference to the drawings and tables.

[0061] In addition, the meanings of the symbols shown in the following tables and descriptions are as shown below.

[0062] "r" represents the paraxial curvature radius of the i-th surface, "d" represents the on-axis surface interval between the i-th surface and the (i + 1)-th surface (the central thickness of the lens or the air interval), "nd" represents the refractive index at the d-line (λ = 587.6 nm) of the lens starting from the i-th surface, and "νd" represents the Abbe number at the d-line of the lens starting from the i-th surface.

[0063] Regarding "r", "∞" indicates that the surface is a plane. Regarding "d", "variable" indicates a variable interval.

[0064] For aspherical surfaces, an asterisk is attached to the right side of the surface number, and for the aperture stop, the description "stop" is attached to the right side of the surface number.

[0065] "κ" is the conic constant (conic coefficient), and "A4", "A6", "A8", "A10", "A12" represent the aspherical coefficients of the 4th, 6th, 8th, 10th, and 12th orders respectively.

[0066] In addition, in each table showing the following aspherical coefficients, "E - n" is an exponential expression with base 10, that is, it represents "10 to the minus n power". For example, "0.12345E - 05" represents "0.12345×(10 to the minus fifth power)".

[0067] Among the zoom lenses used in each embodiment, there are those with lens surfaces formed as aspherical surfaces. The aspherical shape is defined by the following Equation 1, where "x" is the distance (sag amount) in the optical axis direction from the vertex of the lens surface, "y" is the height (image height) in the direction perpendicular to the optical axis direction, "c" is the paraxial curvature (reciprocal of the curvature radius) at the vertex of the lens, "κ" is the conic constant (conic coefficient), and "A4", "A6", ··· are the aspherical coefficients of the 4th, 6th, ··· orders respectively.

[0068] In each figure, the image plane is indicated by "IMG".

[0069]

Equation

[0070] <First Embodiment> Figs. 1 to 6 show the lens configuration of the zoom lens 1 in the first embodiment of the present technology.

[0071] The zoom lens 1 has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6 arranged in order from the object side to the image side. The first lens group G1 is provided as a positive lens group, the second lens group G2 is provided as a positive lens group, and the third lens group G3 is provided as a negative lens group.

[0072] The first lens group G1 is fixed during zooming, and the second lens group G2 and the third lens group G3 are moved during zooming.

[0073] The first lens group G1 is composed of a negative meniscus lens L11 with a convex surface facing the object side, a positive lens L12, and a positive meniscus lens L13 with a convex surface facing the object side, in order from the object side to the image side.

[0074] The second lens group G2 is composed of a positive meniscus lens L21 with a convex surface facing the image side.

[0075] The third lens group G3 is composed of a negative lens L31, a positive lens L32, a negative lens L33, and a negative meniscus lens L34 with a convex surface facing the image side, in order from the object side to the image side. The positive lens L32 and the negative lens L33 are configured as a cemented lens.

[0076] The fourth lens group G4 is composed of a negative lens L41 and a positive meniscus lens L42 with a convex surface facing the object side, in order from the object side to the image side. The negative lens L41 and the positive meniscus lens L42 are configured as a cemented lens.

[0077] The fifth lens group G5 is composed of, in order from the object side to the image side, a positive lens L51, a negative meniscus lens L52 with its convex surface facing the object side, and a positive lens L53. The negative meniscus lens L52 and the positive lens L53 are configured as a cemented lens.

[0078] The sixth lens group G6 is composed of, in order from the object side to the image side, a negative meniscus lens L61 with its convex surface facing the image side, a positive lens L62, an aperture stop S, a positive lens L63, a negative lens L64, a positive lens L65, a positive meniscus lens L66 with its convex surface facing the image side, a negative lens L67, a positive lens L68, a negative lens L69, a positive lens L610, a positive lens L611, a negative lens L612, and a negative lens L613 with its convex surface facing the image side. The positive lens L63 and the negative lens L64 are configured as a cemented lens, the positive meniscus lens L66 and the negative lens L67 are configured as a cemented lens, the positive lens L68 and the negative lens L69 are configured as a cemented lens, and the positive lens L611 and the negative lens L612 are configured as a cemented lens.

[0079] When focusing from infinity to a short distance, the fifth lens group G5 is moved in the optical axis direction. Note that, when focusing, other configurations such as a configuration in which the positive lens L610 is moved in the optical axis direction may be adopted. Also, by moving the positive lens L66 and the negative lens L67 that constitute the cemented lens in a direction orthogonal to the optical axis direction, anti-shake can be performed against camera shake and the like.

[0080] Table 1 shows the lens data of Numerical Example 1 in which specific numerical values are applied to the zoom lens 1.

[0081]

Table 1

[0082] Table 2 shows the focal length f, F-number Fno, semi-field angle ω, image height Y, and overall optical length L of Numerical Example 1.

[0083]

Table 2

[0084] When focusing between infinity and the closest distance (2000 mm), the distances between the first lens group G1 and the second lens group G2, between the second lens group G2 and the third lens group G3, between the third lens group G3 and the fourth lens group G4, between the fourth lens group G4 and the fifth lens group G5, and between the fifth lens group G5 and the sixth lens group G6 change. Table 3 shows the variable distances at infinity and the closest distance for each surface interval in Numerical Example 1.

[0085]

Table 3

[0086] Table 4 shows the focal lengths of each lens group in Numerical Example 1.

[0087]

Table 4

[0088] Figures 7 to 12 are the longitudinal aberration diagrams of Numerical Example 1, and Figures 13 to 18 are the lateral aberration diagrams of Numerical Example 1. In Figures 7 to 12, in spherical aberration, the solid line indicates the value of the d line (587.56 nm), the dotted line indicates the value of the c line (656.27 nm), the dashed-dotted line indicates the value of the g line (435.84 nm), in astigmatism, the solid line indicates the value of the sagittal image plane of the d line, the dashed line indicates the value of the meridional image plane of the d line, and in distortion, the value of the d line is indicated. In Figures 13 to 18, the solid line indicates the value of the d line, the dotted line indicates the value of the c line, and the dashed-dotted line indicates the value of the g line.

[0089] With the above configuration, the zoom lens 1 realizes a high-quality telephoto zoom lens and is also reduced in weight.

[0090] Also, it is clear from each aberration diagram that in Numerical Example 1, various aberrations are well corrected and it has excellent imaging performance.

[0091] <Second Embodiment> Figures 19 to 24 show the lens configuration of the zoom lens 2 in the second embodiment of the present technology.

[0092] The zoom lens 2 has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7, which are arranged in order from the object side to the image side. The first lens group G1 is provided as a positive lens group, the second lens group G2 is provided as a positive lens group, and the third lens group G3 is provided as a negative lens group.

[0093] The first lens group G1 is fixed during zooming, and the second lens group G2 and the third lens group G3 are moved during zooming.

[0094] The first lens group G1 is composed of a negative meniscus lens L11 with a convex surface facing the object side, a positive lens L12, and a positive lens L13, in order from the object side to the image side.

[0095] The second lens group G2 is composed of a positive meniscus lens L21 with a convex surface facing the object side and a negative meniscus lens L22 with a convex surface facing the object side, in order from the object side to the image side.

[0096] The third lens group G3 is composed of a negative lens L31, a negative lens L32, and a positive lens L33, in order from the object side to the image side. The negative lens L32 and the positive lens L33 are configured as a cemented lens.

[0097] The fourth lens group G4 is composed of a positive lens L41, a positive lens L42, a positive lens L43, and a negative lens L44, in order from the object side to the image side. The positive lens L43 and the negative lens L44 are configured as a cemented lens.

[0098] The fifth lens group G5 is composed of, in order from the object side to the image side, an aperture stop S, a positive lens L51, a negative meniscus lens L52 with its convex surface facing the object side, a negative meniscus lens L53 with its convex surface facing the object side, a positive meniscus lens L54 with its convex surface facing the object side, a positive meniscus lens L55 with its convex surface facing the object side, a negative meniscus lens L56 with its convex surface facing the object side, and a positive meniscus lens L57 with its convex surface facing the object side. The negative meniscus lens L53 and the positive meniscus lens L54 are configured as a cemented lens, and the negative meniscus lens L56 and the positive meniscus lens L57 are configured as a cemented lens.

[0099] The sixth lens group G6 is composed of, in order from the object side to the image side, a negative meniscus lens L61 with its convex surface facing the object side, a negative lens L62, and a positive lens L63. The negative lens L62 and the positive lens L63 are configured as a cemented lens.

[0100] The seventh lens group G7 is composed of, in order from the object side to the image side, a positive meniscus lens L71 with its convex surface facing the object side, a positive meniscus lens L72 with its convex surface facing the image side, and a negative meniscus lens L73 with its convex surface facing the image side.

[0101] When focusing from infinity to a short distance, the sixth lens group G6 is moved in the optical axis direction. Note that when focusing, other configurations such as the fourth lens group G4 being moved in the optical axis direction may be adopted. Also, by moving the negative meniscus lens L53 and the positive meniscus lens L54 that constitute the cemented lens in a direction orthogonal to the optical axis direction, anti-shake can be performed against camera shake and the like.

[0102] Table 5 shows the lens data of Numerical Example 2 in which specific numerical values are applied to the zoom lens 2.

[0103]

Table 5

[0104] Table 6 shows the focal length f, F-number Fno, semi-field angle ω, image height Y, and overall optical length L of Numerical Example 2.

[0105]

Table 6

[0106] When focusing between infinity and the closest distance (2000 mm), the distances between the first lens group G1 and the second lens group G2, between the second lens group G2 and the third lens group G3, between the third lens group G3 and the fourth lens group G4, between the fourth lens group G4 and the fifth lens group G5, between the fifth lens group G5 and the sixth lens group G6, and between the sixth lens group G6 and the seventh lens group G7 change. Table 7 shows the variable distances at infinity and the closest distance for each surface interval in Numerical Example 2.

[0107]

Table 7

[0108] Table 8 shows the aspheric coefficients A4, A6, A8, A10, A12 of the 4th, 6th, 8th, 10th, and 12th orders in Numerical Example 2 together with the conic constant κ.

[0109]

Table 8

[0110] Table 9 shows the focal lengths of each lens group in Numerical Example 2.

[0111]

Table 9

[0112] Figs. 25 to 30 are longitudinal aberration diagrams of Numerical Example 2, and Figs. 31 to 36 are lateral aberration diagrams of Numerical Example 2. In Figs. 25 to 30, in spherical aberration, the solid line indicates the value of the d line (587.56 nm), the dotted line indicates the value of the c line (656.27 nm), the dashed-dotted line indicates the value of the g line (435.84 nm), in astigmatism, the solid line indicates the value of the sagittal image plane of the d line, the dashed line indicates the value of the meridional image plane of the d line, and in distortion, the value of the d line is indicated. In Figs. 31 to 36, the solid line indicates the value of the d line, the dotted line indicates the value of the c line, and the dashed-dotted line indicates the value of the g line.

[0113] With the above configuration, the zoom lens 2 realizes a high-quality telephoto zoom lens and is made lightweight.

[0114] Also, it is clear from each aberration diagram that in Numerical Example 2, various aberrations are well corrected and it has excellent imaging performance.

[0115] <The Third Embodiment> Figs. 37 to 42 show the lens configuration of the zoom lens 3 in the third embodiment of the present technology.

[0116] The zoom lens 3 has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6 arranged in order from the object side to the image side. The first lens group G1 is provided as a positive lens group, the second lens group G2 is provided as a positive lens group, and the third lens group G3 is provided as a negative lens group.

[0117] The first lens group G1 is fixed during zooming, and the second lens group G2 and the third lens group G3 are moved during zooming.

[0118] The first lens group G1 is composed of, in order from the object side to the image side, a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, a positive lens L13, and a positive lens L14.

[0119] The second lens group G2 is composed of a positive meniscus lens L21 with a convex surface facing the image side.

[0120] The third lens group G3 is composed of, in order from the object side to the image side, a negative lens L31, a positive lens L32, a negative lens L33, and a negative lens L34. The positive lens L32 and the negative lens L33 are configured as a cemented lens.

[0121] The fourth lens group G4 is composed of, in order from the object side to the image side, a negative lens L41 and a positive meniscus lens L42 with a convex surface facing the object side. The negative lens L41 and the positive meniscus lens L42 are configured as a cemented lens.

[0122] The fifth lens group G5 is composed of, in order from the object side to the image side, a positive lens L51, a negative meniscus lens L52 with a convex surface facing the object side, and a positive lens L53. The negative meniscus lens L52 and the positive lens L53 are configured as a cemented lens.

[0123] The sixth lens group G6 is composed of, in order from the object side to the image side, a negative meniscus lens L61 with a convex surface facing the image side, a positive meniscus lens L62 with a convex surface facing the object side, an aperture stop S, a positive lens L63, a negative lens L64, a positive meniscus lens L65 with a convex surface facing the object side, a positive lens L66, a negative lens L67, a positive lens L68, a negative meniscus lens L69 with a convex surface facing the image side, a positive lens L610, a positive meniscus lens L611 with a convex surface facing the image side, a negative meniscus lens L612 with a convex surface facing the image side, and a negative lens L613. The positive lens L63 and the negative lens L64 are configured as a cemented lens, the positive lens L66 and the negative lens L67 are configured as a cemented lens, and the positive meniscus lens L611 and the negative meniscus lens L612 are configured as a cemented lens.

[0124] When focusing from infinity to a short distance, the fifth lens group G5 is moved in the optical axis direction. Incidentally, when focusing, other configurations such as a configuration in which the positive meniscus lens L611 and the negative meniscus lens L612 are moved in the optical axis direction may be employed. Further, by moving the positive lens L66 and the negative lens L67 that constitute the cemented lens in a direction orthogonal to the optical axis direction, it is possible to perform anti-shake against camera shake and the like.

[0125] Table 10 shows the lens data of Numerical Example 3 in which specific numerical values are applied to the zoom lens 3.

[0126]

Table 10

[0127] Table 11 shows the focal length f, F-number Fno, semi-field angle ω, image height Y, and overall optical length L of Numerical Example 3.

[0128]

Table 11

[0129] When focusing between infinity and the closest distance (2000 mm), the distances between the first lens group G1 and the second lens group G2, between the second lens group G2 and the third lens group G3, between the third lens group G3 and the fourth lens group G4, between the fourth lens group G4 and the fifth lens group G5, and between the fifth lens group G5 and the sixth lens group G6 change. Table 12 shows the variable distances at infinity and the closest distance for each surface interval in Numerical Example 3.

[0130]

Table 12

[0131] Table 13 shows the focal lengths of the respective lens groups in Numerical Example 3.

[0132]

Table 13

[0133] Figs. 43 to 48 are vertical aberration diagrams of Numerical Example 3, and Figs. 49 to 54 are horizontal aberration diagrams of Numerical Example 3. In Figs. 43 to 48, in spherical aberration, the solid line indicates the value of the d-line (587.56 nm), the dotted line indicates the value of the c-line (656.27 nm), the one-dot chain line indicates the value of the g-line (435.84 nm), in astigmatism, the solid line indicates the value of the sagittal image plane of the d-line, the broken line indicates the value of the meridional image plane of the d-line, and in distortion aberration, the value of the d-line is indicated. In Figs. 49 to 54, the solid line indicates the value of the d-line, the dotted line indicates the value of the c-line, and the one-dot chain line indicates the value of the g-line.

[0134] With the above configuration, the zoom lens 3 realizes a high-quality telephoto zoom lens and is made lightweight.

[0135] Also, from each aberration diagram, it is clear that in Numerical Example 3, various aberrations are well corrected and it has excellent imaging performance.

[0136] <Fourth Embodiment> Figs. 55 to 60 show the lens configuration of the zoom lens 4 in the fourth embodiment of the present technology.

[0137] The zoom lens 4 has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a fifth lens group G5, and a sixth lens group G6 arranged in order from the object side to the image side. The first lens group G1 is provided as a positive lens group, the second lens group G2 is provided as a positive lens group, and the third lens group G3 is provided as a negative lens group.

[0138] The first lens group G1 is fixed during zooming, and the second lens group G2 and the third lens group G3 are moved during zooming.

[0139] The first lens group G1 is composed of, in order from the object side to the image side, a negative meniscus lens L11 with a convex surface facing the object side, a positive meniscus lens L12 with a convex surface facing the object side, and a positive lens L13.

[0140] The second lens group G2 is composed of, in order from the object side to the image side, a positive meniscus lens L21 with a convex surface facing the object side and a negative meniscus lens L22 with a convex surface facing the object side.

[0141] The third lens group G3 is composed of, in order from the object side to the image side, a negative lens L31, a negative lens L32, and a positive lens L33. The negative lens L32 and the positive lens L33 are configured as a cemented lens.

[0142] The fourth lens group G4 is composed of, in order from the object side to the image side, a positive meniscus lens 41 with a convex surface facing the image side, a positive lens L42, a positive lens L43, a negative lens L44, an aperture stop S, a positive lens L45, a negative meniscus lens L46 with a convex surface facing the object side, a negative meniscus lens L47 with a convex surface facing the object side, a positive meniscus lens L48 with a convex surface facing the object side, a positive meniscus lens L49 with a convex surface facing the object side, a negative meniscus lens L410 with a convex surface facing the object side, and a positive meniscus lens L411 with a convex surface facing the object side. The positive lens L43 and the negative lens L44 are configured as a cemented lens, the negative meniscus lens L47 and the positive meniscus lens L48 are configured as a cemented lens, and the negative meniscus lens L410 and the positive meniscus lens L411 are configured as a cemented lens.

[0143] The fifth lens group G5 is composed of, in order from the object side to the image side, a negative meniscus lens L51 with a convex surface facing the object side, a negative lens L52, and a positive lens L53. The negative lens L52 and the positive lens L53 are configured as a cemented lens.

[0144] The sixth lens group G6 is composed of, in order from the object side to the image side, a positive meniscus lens L61 with a convex surface facing the object side, a positive meniscus lens L62 with a convex surface facing the image side, and a negative meniscus lens L63 with a convex surface facing the image side.

[0145] When focusing from infinity to a short distance, the fifth lens group G5 is moved in the optical axis direction. Incidentally, when focusing, other configurations such as a configuration in which the positive lens 41, the positive lens L42, the positive lens L43, and the negative lens L44 are moved in the optical axis direction may be employed. Further, by moving the negative meniscus lens L47 and the positive meniscus lens L48 that constitute the cemented lens in a direction orthogonal to the optical axis direction, it is possible to perform anti-shake against camera shake and the like.

[0146] Table 14 shows the lens data of Numerical Example 4 in which specific numerical values are applied to the zoom lens 4.

[0147]

Table 14

[0148] Table 15 shows the focal length f, F-number Fno, semi-field angle ω, image height Y, and overall optical length L of Numerical Example 4.

[0149]

Table 15

[0150] When focusing between infinity and the closest distance (2000 mm), the distances between the first lens group G1 and the second lens group G2, between the second lens group G2 and the third lens group G3, between the third lens group G3 and the fourth lens group G4, between the fourth lens group G4 and the fifth lens group G5, and between the fifth lens group G5 and the sixth lens group G6 change. Table 16 shows the variable distances at infinity and the closest distance for each surface interval in Numerical Example 4.

[0151]

Table 16

[0152] Table 17 shows the aspherical coefficients A4, A6, A8, A10, A12 of the 4th, 6th, 8th, 10th, and 12th orders together with the conic constant κ in Numerical Example 4.

[0153]

Table 17

[0154] The focal lengths of each lens group in Numerical Example 4 are shown in Table 18.

[0155]

Table 18

[0156] Figures 61 to 66 are the longitudinal aberration diagrams of Numerical Example 4, and Figures 67 to 72 are the lateral aberration diagrams of Numerical Example 4. In Figures 61 to 66, in spherical aberration, the solid line indicates the value of the d line (587.56 nm), the dotted line indicates the value of the c line (656.27 nm), the dashed-dotted line indicates the value of the g line (435.84 nm), in astigmatism, the solid line indicates the value of the sagittal image plane of the d line, the dashed line indicates the value of the meridional image plane of the d line, and in distortion, the value of the d line is indicated. In Figures 67 to 72, the solid line indicates the value of the d line, the dotted line indicates the value of the c line, and the dashed-dotted line indicates the value of the g line.

[0157] With the above configuration, the zoom lens 4 realizes a high-quality telephoto zoom lens and is also made lightweight.

[0158] Also, it is clear from each aberration diagram that in Numerical Example 4, various aberrations are well corrected and it has excellent imaging performance.

[0159] [Each value of the conditional expressions of the zoom lens] The following explains each value of the conditional expressions of the zoom lens of the present technology.

[0160] Table 19 shows each value of Conditional Expressions (1) to (5) in Numerical Examples 1 to 4 of Zoom Lenses 1 to 4.

[0161]

Table 19

[0162] As is clear from Table 19, the zoom lenses 1 to 4 are configured to satisfy the conditional expressions (1) to (5).

[0163] [Configuration of Imaging Device] The imaging device of the present technology has a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side. The first lens group is fixed during zooming, and the second lens group and the third lens group are moved during zooming. The first lens group is composed of 4 or fewer lenses and satisfies the following conditional expressions (1) and (2). (1) 1.00 < f2 / f1 < 11.00 (2) 0.57 < m2 / m3 < 0.95 However, f1: Focal length of the first lens group f2: Focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end Let it be

[0164] As described above, having a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, with the first lens group being composed of 4 or fewer lenses and fixed during zooming, and the second lens group and the third lens group being moved during zooming, it becomes possible to reduce the weight of the optical system. Also, although the first lens group has a small number of lenses, by making the second lens group a positive lens group, the total refractive power is increased and good aberration correction can be achieved.

[0165] Since the zoom lens of the imaging device of the present technology satisfies the conditional expression (1), the refractive power of the first lens group is optimized, the diameter of the optical system can be reduced, and various aberrations, particularly spherical aberration, axial chromatic aberration, and magnification chromatic aberration, can be corrected well.

[0166] In addition, when the zoom lens of the present technology imaging device satisfies the conditional expression (2), the diameter of the light beam incident on the second lens group at the telephoto end becomes smaller and the reduction effect during zooming by the second lens group is suppressed. Therefore, it is possible to reduce the size of the optical system and increase the magnification. As described above, according to the present technology imaging device, it is possible to provide an imaging device equipped with a zoom lens that is lightweight and corrects various aberrations well.

[0167] [One Embodiment of the Imaging Device] Fig. 73 shows a block diagram of a digital still camera according to one embodiment of the present technology imaging device.

[0168] An imaging device (digital still camera) 100 includes an imaging element 10 having a photoelectric conversion function that converts the captured light into an electrical signal, a camera signal processing unit 20 that performs signal processing such as analog-digital conversion of the captured image signal, and an image processing unit 30 that performs recording and playback processing of the image signal. In addition, the imaging device 100 includes a display unit 40 that displays the captured image and the like, an R / W (reader / writer) 50 that writes and reads the image signal to / from the memory 90, a CPU (Central Processing Unit) 60 that controls the entire imaging device 100, an input unit 70 such as various switches for performing required operations by the user, and a lens drive control unit 80 that controls the drive of the zoom lens 1 (including the zoom lens 2, the zoom lens 3, and the zoom lens 4).

[0169] The camera signal processing unit 20 performs various signal processes such as conversion of the output signal from the imaging element 10 into a digital signal, noise removal, image quality correction, and conversion into luminance / chrominance signals.

[0170] The image processing unit 30 performs compression encoding / expansion decoding processing of the image signal based on a predetermined image data format, conversion processing of data specifications such as resolution, and the like.

[0171] The display unit 40 has a function of displaying various data such as the operation state with respect to the user input unit 70 and the captured image.

[0172] R / W50 writes the image data encoded by the image processing unit 30 to the memory 90 and reads the image data recorded in the memory 90.

[0173] The CPU 60 functions as a control processing unit that controls each circuit block provided in the imaging device 100, and controls each circuit block based on an instruction input signal or the like from the input unit 70.

[0174] The input unit 70 outputs an instruction input signal corresponding to an operation by the user to the CPU 60.

[0175] The lens drive control unit 80 controls a motor (not shown) or the like that drives the lens group based on a control signal from the CPU 60.

[0176] The memory 90 is, for example, a semiconductor memory that is detachable with respect to a slot connected to the R / W 50. Note that the memory 90 may not be detachable with respect to the slot and may be incorporated inside the imaging device 100.

[0177] The operation of the imaging device 100 will be described below.

[0178] In the standby state for shooting, under the control of the CPU 60, the captured image signal is output to the display unit 40 via the camera signal processing unit 20 and is displayed as a camera through image.

[0179] When shooting is performed by an instruction input signal from the input unit 70, the captured image signal is output from the camera signal processing unit 20 to the image processing unit 30, compressed and encoded, and converted into digital data in a predetermined data format. The converted data is output to the R / W 50 and written to the memory 90.

[0180] Focusing is performed by the lens drive control unit 80 moving the focus lens group based on a control signal from the CPU 60.

[0181] When reproducing the image data recorded in the memory 90, in response to an operation on the input unit 70, predetermined image data is read from the memory 90 by the R / W 50. After the decompression and decoding process is performed by the image processing unit 30, the reproduced image signal is output to the display unit 40 and the reproduced image is displayed.

[0182] In addition, in this technology, "imaging" refers to only a part or all of a series of processes from the photoelectric conversion process of converting the light captured by the imaging device 10 into an electrical signal, to the conversion of the output signal from the imaging device 10 by the camera signal processing unit 20 into a digital signal, noise removal, image quality correction, conversion to luminance / chrominance signals, etc., the compression encoding / decompression decoding process of the image signal based on a predetermined image data format by the image processing unit 30, the conversion process of data specifications such as resolution, and the writing process of the image signal to the memory 90 by the R / W 50.

[0183] That is, "imaging" may refer only to the photoelectric conversion process of converting the light captured by the imaging device 10 into an electrical signal, or may refer to the processes from the photoelectric conversion process of converting the light captured by the imaging device 10 into an electrical signal to the conversion of the output signal from the imaging device 10 by the camera signal processing unit 20 into a digital signal, noise removal, image quality correction, conversion into luminance / chrominance signals, etc., or may refer to the processes from the photoelectric conversion process of converting the light captured by the imaging device 10 into an electrical signal to the conversion of the output signal from the imaging device 10 by the camera signal processing unit 20 into a digital signal, noise removal, image quality correction, conversion into luminance / chrominance signals, etc., and then through the processes such as compression encoding / expansion decoding processing of the image signal based on a predetermined image data format by the image processing unit 30 and conversion processing of data specifications such as resolution, or may refer to the processes from the photoelectric conversion process of converting the light captured by the imaging device 10 into an electrical signal to the conversion of the output signal from the imaging device 10 by the camera signal processing unit 20 into a digital signal, noise removal, image quality correction, conversion into luminance / chrominance signals, etc., and the processes such as compression encoding / expansion decoding processing of the image signal based on a predetermined image data format by the image processing unit 30 and conversion processing of data specifications such as resolution, or may refer to up to the writing process of the image signal to the memory 90 by the R / W 50. In the above processes, the order of each process may be appropriately interchanged.

[0184] Also, in the present technology, the imaging device 100 may be configured to include only a part or all of the above-described imaging device 10, camera signal processing unit 20, image processing unit 30, and R / W 50 that perform the above processes.

[0185] [Others] In the present technology zoom lens and the present technology imaging device, other optical elements such as lenses having no refractive power may be arranged in addition to the first lens group G1 to the sixth lens group G6 or in addition to the first lens group G1 to the seventh lens group G7. In this case, the lens configuration of the present technology zoom lens is substantially a six-group or seven-group lens configuration of the first lens group G1 to the sixth lens group G6 or the first lens group G1 to the seventh lens group G7.

[0186] Although an example in which the imaging device is applied to a digital still camera has been shown above, the application range of the imaging device is not limited to digital still cameras, and it can be widely applied to digital video cameras, camera units of digital input / output devices in portable terminals such as mobile phones incorporating cameras, and the like.

[0187] [This technology] This technology can also be configured as follows.

[0188] <1> It has a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side. The first lens group is fixed during zooming, and the second lens group and the third lens group are moved during zooming. The first lens group is composed of 4 or fewer lenses. Satisfying the following conditional expressions (1) and (2) Zoom lens. (1) 1.00 < f2 / f1 < 11.00 (2) 0.57 < m2 / m3 < 0.95 However, f1: Focal length of the first lens group f2: Focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end Let it be.

[0189] <2> Satisfying the following conditional expression (3) The zoom lens according to <1> above. (3) -5.0 < f1 / f23w < -1.0 However, f23w: Composite focal length of the second lens group and the third lens group at the wide-angle end Let it be.

[0190] <3> Satisfying the following conditional expression (4) The zoom lens according to the above <1> or <2>. (4) 0.35 < f1 / ft < 1.20 However, ft: The focal length of the entire system at the telephoto end shall be.

[0191] <4> Satisfying the following conditional expression (5) The zoom lens according to any one of the above <1> to <3>. (5) 2.1 < d1t / d2t < 9.9 However, d1t: The distance between the first lens group and the second lens group at the telephoto end d2t: The distance between the second lens group and the third lens group at the telephoto end shall be.

[0192] <5> Focusing by moving all or part of the group located on the image side of the third lens group in the optical axis direction The zoom lens according to any one of the above <1> to <4>.

[0193] <6> An imaging device including a zoom lens and an image sensor that converts an optical image formed by the zoom lens into an electrical signal, wherein the zoom lens has a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, the first lens group is fixed during zooming and the second lens group and the third lens group are moved during zooming, the first lens group is composed of 4 or fewer lenses, satisfying the following conditional expressions (1) and (2) Imaging device. (1) 1.00 < f2 / f1 < 11.00 (2) 0.57 < m2 / m3 < 0.95 However, f1: The focal length of the first lens group f2: The focal length of the second lens group m2: Movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: Movement amount of the third lens group during zooming from the wide-angle end to the telephoto end Let it be so.

Explanation of symbols

[0194] 1 Zoom lens 2 Zoom lens 3 Zoom lens 4 Zoom lens 100 Imaging device G1 First lens group G2 Second lens group G3 Third lens group

Claims

1. A zoom lens having six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, wherein the interval between adjacent lens groups changes during zooming, the first lens group is fixed during zooming and the second lens group and the third lens group are moved during zooming, the first lens group is composed of 4 or fewer lenses, and satisfying the following conditional expressions (1), (2A), and (4): A zoom lens. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (4) 0.35 < f1 / ft < 1.20 However, f1: the focal length of the first lens group f2: the focal length of the second lens group m2: the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end ft: the focal length of the entire system at the telephoto end shall be defined as such.

2. A zoom lens having six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, wherein the interval between adjacent lens groups changes during zooming, the first lens group is fixed during zooming and the second lens group and the third lens group are moved during zooming, the first lens group is composed of 4 or fewer lenses, and satisfying the following conditional expressions (1), (2A), and (5): A zoom lens. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (5) 2.1 < d1t / d2t < 9.9 However, f1: the focal length of the first lens group f2: the focal length of the second lens group m2: the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end d1t: the interval between the first lens group and the second lens group at the telephoto end d2t: the interval between the second lens group and the third lens group at the telephoto end shall be defined as such.

3. Satisfying the following conditional expression (3): The zoom lens according to Claim 1 or Claim 2. (3) -5.0 < f1 / f23w < -1.0 However, f23w: the combined focal length of the second lens group and the third lens group at the wide-angle end shall be defined as such.

4. Focusing by moving all or part of the group located on the image side of the third lens group in the optical axis direction The zoom lens according to Claim 1 or Claim 2.

5. A zoom lens and an imaging device that converts an optical image formed by the zoom lens into an electrical signal, wherein the zoom lens has six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, the interval between adjacent lens groups changes during zooming, the first lens group is fixed during zooming and the second lens group and the third lens group are moved during zooming, the first lens group is composed of 4 or fewer lenses, satisfies the following conditional expressions (1), (2A), and (4) imaging device. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (4) 0.35 < f1 / ft < 1.20 provided that f1: the focal length of the first lens group f2: the focal length of the second lens group m2: the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end ft: the focal length of the entire system at the telephoto end is defined as.

6. A zoom lens and an imaging device that converts an optical image formed by the zoom lens into an electrical signal, wherein the zoom lens has six or more lens groups including a positive first lens group, a positive second lens group, and a negative third lens group arranged in order from the object side to the image side, the interval between adjacent lens groups changes during zooming, the first lens group is fixed during zooming and the second lens group and the third lens group are moved during zooming, the first lens group is composed of 4 or fewer lenses, satisfies the following conditional expressions (1), (2A), and (5) imaging device. (1) 1.00 < f2 / f1 < 11.00 (2A) 0.59 < m2 / m3 < 0.94 (5) 2.1 < d1t / d2t < 9.9 provided that f1: the focal length of the first lens group f2: the focal length of the second lens group m2: the movement amount of the second lens group during zooming from the wide-angle end to the telephoto end m3: the movement amount of the third lens group during zooming from the wide-angle end to the telephoto end d1t: the interval between the first lens group and the second lens group at the telephoto end d2t: the interval between the second lens group and the third lens group at the telephoto end is defined as.

Images