Macro lens system and imaging device

Abstract

Macro lens system, consisting, in this order starting from one side of the object, of: a first lens group (G1) with a positive refractive power; a second lens group (G2) with a negative refractive power; a third lens group (G3) with a positive refractive power; a fourth lens group (G4) with a positive refractive power; a fifth lens group (G5) with a positive refractive power; and a sixth lens group (G6) with a negative refractive power; wherein the first lens group (G1) consists of three lenses; and the second lens group (G2), the fourth lens group (G4) and the fifth lens group (G5) are moved independently in the direction of their optical axes when focusing from an object at infinity to an object at its nearest distance, and wherein the macrolens system satisfies the following condition formula (5): 0.5 < f 3 / f < 1.0 where f denotes the focal length when focusing on an object at infinity, and f3 denotes the focal length of the third lens group (G3).

Description

BACKGROUND OF THE INVENTIONTechnical field

[0001] The present invention relates to a macro lens system suitable for electronic cameras such as digital cameras, video cameras, broadcast cameras and security cameras, and an imaging device equipped with the macro lens system. State of the art

[0002] Conventional macro lens systems exist with close-up imaging at image magnification ratios of approximately 1x as their primary purpose.

[0003] These macro lens systems are capable of continuously focusing from an object at infinity to an object at a closest distance, where the image magnification ratio is approximately 1x. The macro lens systems are designed to achieve high optical performance when imaging objects at close distances.

[0004] Generally, the floating focus method, in which two or more lens groups are moved during focusing operations, is used to suppress variations in aberration accompanying the focusing operations.

[0005] Traditionally, the front-focusing type of focusing operation, in which the lens group closest to the object is moved forward, was used. However, when imaging an object at the closest distance, the lens will move closer to the object, thereby degrading performance. In addition, when a large-diameter first lens group is moved, high-speed focusing becomes difficult due to the heavy weight of the first lens group. In addition, there was a problem that longitudinal chromatic aberrations become large when performing close-distance imaging at a magnification of approximately 1x.

[0006] Recently, imaging lenses employing the floating focus method, in which a first lens group is fixed and focusing operations are performed by moving a plurality of other lens groups, have been used. Other focusing methods that move three or more lens groups to further suppress aberration variations due to focusing operations have been proposed in Patent Documents 1 and 2. [Prior art documents][Patent documents] [Patent Document 1]Japanese Unexamined Patent Publication JP 2012-058682 A [Patent Document 2] Japanese Unexamined Patent Publication JP 2011-048232 A SUMMARY OF THE INVENTION

[0007] The focusing method disclosed in Patent Document 1 requires a large number of lenses, resulting in the weight of the lens system itself becoming large, which is disadvantageous from the point of view of portability.

[0008] The focusing method disclosed in Patent Document 2 uses a lens system with a small number of lenses and is relatively light, but cannot be called compact.

[0009] Another macro lens system is known from patent document US 8,446,678 B2.

[0010] The object of the present invention is to provide a miniature macro lens system with an imaging magnification of approximately 1x, which favorably corrects chromatic aberrations even when imaging at close distances, and an imaging device equipped with the macro lens system.

[0011] A macro lens system according to the invention consists, in this order starting from one object side, of: a first lens group with a positive refractive power; a second lens group with a negative refractive power; a third lens group with a positive refractive power; a fourth lens group with a positive refractive power; a fifth lens group with a positive refractive power; and a sixth lens group with a negative refractive power; and is characterized in that the first lens group consists of three lenses; and the second lens group, the fourth lens group and the fifth lens group are moved independently of each other in the direction of their optical axes when focusing from an object at infinity to an object at a closest distance.

[0012] In addition, the macro lens system satisfies the following conditional formula (5): 0.5 <f3 / f<1,0 where f is the focal length when focusing on an object at infinity, and f3 is the focal length of the third lens group.

[0013] In the macro lens system according to the invention, it is preferable to adopt a configuration in which: the first lens group, in this order starting from the object side, consists of a cemented lens consisting of a negative lens and a positive lens with a convex cemented surface, and a positive lens.

[0014] Additionally, it is preferred if: the first lens group has at least one positive lens; and at least exactly one positive lens satisfies the following conditional formulas (1) and (2): N1d<1.60 60.0<ν1d where N1d denotes the refractive index of the positive lens in the first lens group with respect to the d-line and v1d denotes the Abbe number of the positive lens in the first lens group with respect to the d-line.

[0015] Additionally, it is preferred if: the second lens group comprises a cemented lens formed by a negative lens and a positive lens, and satisfies the following conditional formula (3): 25.0<ν2dn−ν2dp where v2dp denotes the Abbe number of the positive lens forming the cemented lens of the second lens group with respect to the d-line and v2dn denotes the Abbe number of the negative lens forming the cemented lens of the second lens group with respect to the d-line.

[0016] Additionally, it is preferred if: the third lens group is formed from a single positive lens and satisfies the following conditional formula (4): ν3d<30.0 where v3d is the Abbe number of the positive lens of the third lens group (G3) with respect to the d-line.

[0017] Additionally, it is preferred if: at least exactly one surface within the first lens group is aspherical.

[0018] Additionally, it is preferred if: at least exactly one surface within the second lens group is aspherical.

[0019] In addition, it is preferable if the macro lens system satisfies the following conditional formula (6): 1.0 <f4 / f<2,0 where f is the focal length when focusing on an object at infinity, and f4 is the focal length of the fourth lens group.

[0020] Additionally, it is preferred if: the fourth lens group and the fifth lens group, when focusing from an object at infinity to an object at a closest distance, are moved along their optical axes toward the object side; and the macro lens system satisfies the following conditional formula (7): 0.7 <D4 / D5<1,5 where D4 denotes the amount of focusing movement of the fourth lens group from a state where an object at infinity is in focus to a state where an object at a closest distance is in focus, and D5 denotes the amount of focusing movement of the fifth lens group from a state where an object at infinity is in focus to a state where an object at a closest distance is in focus.

[0021] It is preferred if: the fourth lens group has a cemented lens on the side closest to the object side, which is formed by a negative lens and a positive lens.

[0022] In this case, it is preferable if the macro lens system satisfies the following conditional formula (8): 20<ν4dp−ν4dn where v4dp denotes the Abbe number of the positive lens forming the cemented lens of the fourth lens group (G4) with respect to the d-line and v4dn denotes the Abbe number of the negative lens forming the cemented lens of the fourth lens group (G4) with respect to the d-line.

[0023] It is preferred if: the distance between the fourth lens group and the fifth lens group increases and then decreases when focusing from an object at infinity to an object at a closest distance.

[0024] Additionally, it is preferred if: the fourth lens group has two positive lenses; and the macro lens system satisfies the following conditional formula (9): 60.0<ν4d where v4d is the average Abbe number of the positive lenses in the fourth lens group with respect to the d-line.

[0025] It is preferred if: the total number of lenses constituting the lens groups that move during focusing operations is 7 or less.

[0026] Additionally, it is preferred if: the first lens group has at least one positive lens; and at least exactly one positive lens satisfies the following conditional formulas (1) and (2-1): N1d<1.60 65.0<ν1d

[0027] Additionally, it is preferred if: the second lens group comprises a cemented lens formed by a negative lens and a positive lens, and satisfies the following conditional formula (3-1): 30.0<ν2dn−ν2dp

[0028] Additionally, it is preferred if: the third lens group is formed from a single positive lens and satisfies the following conditional formula (4-1): ν3d<25.0

[0029] It is preferred if: the macro lens system satisfies the following conditional formula (5-1), particularly preferably the following conditional formula (5-2): 0.6 <f3 / f<0,9 0.65 <f3 / f<0,8

[0030] Additionally, it is preferred if: the macro lens system satisfies the following conditional formula (6-1): 1.1 <f4 / f<1,8

[0031] Additionally, it is preferred if: the fourth lens group and the fifth lens group, when focusing from an object at infinity to an object at a closest distance, are moved along their optical axes toward the object side; and the macro lens system satisfies the following conditional formula (7-1), particularly preferably the following conditional formula (7-2): 0.8 <D4 / D5<1,3 0.9 <D4 / D5<1,1

[0032] Additionally, it is preferred if: the second lens group comprises a cemented lens formed by a negative lens and a positive lens, and satisfies the following conditional formula (8-1), particularly preferably the following conditional formula (8-2): 25 <v4dp−v4dn 30 <v4dp−v4dn

[0033] An imaging device according to the invention is characterized in that it is equipped with the macro lens system according to the invention.

[0034] It should be noted that the term “consists essentially of” means that the macro lens system may include, in addition to the lenses mentioned above as constituents, lenses having virtually no refractive power, optical elements other than lenses such as a diaphragm, a mask, a glass cover and a filter, mechanical components such as lens flanges, a lens barrel, an imaging element, and a camera shake correction mechanism.

[0035] In addition, the surface shapes and signs of the refractive powers of the lenses in the near-axis (paraxial) region are considered when aspherical surfaces are included.

[0036] The macro lens system according to the invention consists, in this order from the object side, of: the first lens group with a positive refractive power; the second lens group with a negative refractive power; the third lens group with a positive refractive power; the fourth lens group with a positive refractive power; the fifth lens group with a positive refractive power; and the sixth lens group with a negative refractive power; and is characterized in that: the first lens group consists of three lenses; and the second lens group, the fourth lens group, and the fifth lens group are moved independently of each other in the direction of their optical axes when focusing from an object at infinity to an object at a closest distance. Therefore, the macro lens system can be miniaturized and is capable of favorably correcting chromatic aberrations even when imaging at close distances.

[0037] The imaging device according to the invention is equipped with the macro lens system according to the invention. Therefore, the imaging device can be miniaturized and is capable of producing images with high image quality. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] A collection of sectional diagrams illustrating the lens configuration of a macro lens system according to an embodiment of the present invention (corresponding to Example 1). [ Fig. 2] A diagram illustrating the movement trajectories of each lens group of the macro lens system according to the embodiment of the present invention (corresponding to Example 1) during a focusing operation [ Fig. 3] A collection of sectional diagrams illustrating the lens configuration of a macro lens system according to Example 2 of the present invention. [ Fig.4] A diagram illustrating the movement trajectories of each lens group of the macro lens system according to Example 2 of the present invention during a focusing operation [ Fig. 5] A collection of sectional diagrams illustrating the lens configuration of a macro lens system according to Example 3 of the present invention. [ Fig. 6] A diagram illustrating the movement trajectories of each lens group of the macro lens system according to Example 3 of the present invention during a focusing operation [ Fig. 7] A collection of sectional diagrams illustrating the lens configuration of a macro lens system according to Example 4 of the present invention. [ Fig. 8] A diagram illustrating the movement trajectories of each lens group of the macro lens system according to Example 4 of the present invention during a focusing operation [ Fig.9] A collection of sectional diagrams illustrating the lens configuration of a macro lens system according to Example 5 of the present invention. [ Fig. 10] A diagram illustrating the movement trajectories of each lens group of the macro lens system according to Example 5 of the present invention during a focusing operation [ Fig. 11] A collection of diagrams (A to L) illustrating each type of aberration of the macro lens system of Example 1 of the present invention. [ Fig. 12] A collection of diagrams (A to L) illustrating each type of aberration of the macro lens system of Example 2 of the present invention. [ Fig. 13] A collection of diagrams (A to L) illustrating each type of aberration of the macro lens system of Example 3 of the present invention. [ Fig.14] A collection of diagrams (A to L) illustrating each type of aberration of the macro lens system of Example 4 of the present invention. [ Fig. 15] A collection of diagrams (A to L) illustrating each type of aberration of the macro lens system of Example 5 of the present invention. [ Fig. 16A] A collection of schematic diagrams illustrating an imaging apparatus according to an embodiment of the present invention. [ Fig. 16B] A collection of schematic diagrams illustrating an imaging apparatus according to an embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying figures. Fig.1 is a collection of sectional diagrams illustrating the lens configuration of a macro lens system according to an embodiment of the present invention, and Fig. Figure 2 is a diagram illustrating the motion trajectories of each lens group of the macro lens system. Fig. 1 and Fig. The macro lens system illustrated in Figure 2 has the same configuration as the macro lens system of Example 1, which will be described later. Fig. 1 and Fig. 2 the left side is the object side and the right side is the image side.

[0039] As in Fig. 1 and Fig.As illustrated in Figure 2, the macro lens system includes, in this order from the object side along an optical axis Z, a first lens group G1 with a positive refractive power, a second lens group G2 with a negative refractive power, a third lens group G3 with a positive refractive power, an aperture stop St, a fourth lens group G4 with a positive refractive power, a fifth lens group G5 with a positive refractive power, and a sixth lens group G6 with a negative refractive power. The macro lens system is configured such that the second lens group G2, the fourth lens group G4, and the fifth lens group G5 are moved independently of each other along the direction of their optical axes when focusing from an object at infinity to an object at a closest distance.It should be noted that the aperture stop St in the drawings does not necessarily represent the size or shape of the aperture stop, but indicates the position of the stop along the optical axis Z.

[0040] When the macro lens system is mounted on an imaging device, it is preferable to provide a glass cover, a prism, and various filters such as an infrared ray cut-off filter and a low-pass filter between the optical system and the imaging surface Sim. Therefore, Fig. 1 shows an example in which a plane-parallel optical element PP is provided between the lens system and the imaging surface Sim, which takes into account the arrangement of such filters.

[0041] Variations in aberration during focusing operations can be suppressed and favorable image focusing performance can be achieved by configuring the macro lens system with six groups which are, in order from the object side, positive, negative, positive, positive, and negative, and by independently moving the second lens group G2, the fourth lens group G4, and the fifth lens group 5G in the direction of their optical axes during focusing operations as described above.

[0042] In addition, by forming the first lens group G1 with three lenses L11 to L13, the number of lenses with large outer diameters in the first lens group G1 can be reduced, which contributes to miniaturization, cost reduction and weight reduction.

[0043] In the macro lens system of the present embodiment, it is preferable that the first lens group G1 is composed, in this order from the object side, of a cemented lens formed by a negative lens L11 and a positive lens L12 with a convex cemented surface facing the object side, and a positive lens L13L. By providing such a cemented lens, axial chromatic aberrations can be suppressed across an entire screen. In addition, spherical aberrations can be suppressed by providing the positive lens L13.

[0044] Furthermore, it is preferable that the first lens group includes at least one positive lens, and that at least one positive lens satisfies the following conditional formulas (1) and (2). Conditional formulas (1) and (2) are formulas relating to the refractive index and Abbe number of the positive lens of the first lens group G1. When the positive lens satisfies conditional formulas (1) and (2), it becomes possible to perform well-balanced correction of chromatic aberrations when imaging objects at infinity and when imaging objects at closest distances. It should be noted that even more favorable characteristics can be obtained when the positive lens satisfies conditional formulas (1) and (2-1). N1d<1.60 60.0 <v1d 65.0 <v1d where N1d denotes the refractive index of the positive lens in the first lens group with respect to the d-line and v1d denotes the Abbe number of the positive lens in the first lens group with respect to the d-line.

[0045] Additionally, it is preferable that the second lens group includes a cemented lens formed by a negative lens and a positive lens and satisfies the following conditional formula (3). Conditional formula (3) refers to the Abbe number of the cemented lens in the second lens group G2. When the second lens group satisfies conditional formula (3), it becomes possible to perform well-balanced correction of chromatic aberrations when imaging objects at infinity and when imaging objects at close distances. Note that even more favorable characteristics can be obtained when the second lens group satisfies conditional formula (3-1). 25.0 <v2dn−v2dp 30.0 <v2dn−v2dp where v2dp denotes the Abbe number of the positive lens forming the cemented lens of the second lens group with respect to the d-line and v2dn denotes the Abbe number of the negative lens forming the cemented lens of the second lens group with respect to the d-line.

[0046] Additionally, it is preferable if the third lens group is formed from a single positive lens and satisfies the following conditional formula (4). Conditional formula (4) refers to the Abbe number of the positive lens in the third lens group G3. When the third lens group satisfies conditional formula (4), it becomes possible to achieve well-balanced correction of chromatic aberrations when imaging objects at infinity and when imaging objects at close distances. Note that even more favorable performance can be achieved when the third lens group satisfies conditional formula (4-1). v3d<30.0 v3d<25.0 where v3d is the Abbe number of the positive lens of the third lens group with respect to the d-line.

[0047] In addition, it is preferable if the macro lens system satisfies the following conditional formula (5). Conditional formula (5) refers to the refractive power of the third lens group G3. The refractive power of the third lens group G3 can be prevented from becoming too strong, and spherical aberrations can be favorably corrected if the refractive power of the third lens group G3 is not less than the lower limit of conditional formula (5). In addition, if the refractive power of the third lens group G3 does not exceed the upper limit of conditional formula (5), the refractive power of the third lens group G3 can be prevented from becoming too weak, and the outer diameters of the moving lens groups can be kept small, resulting in weight reduction and high-speed focusing operations.It should be noted that even more favorable properties can be obtained if the following conditional formula (5-1) and particularly preferably conditional formula (5-2) are satisfied. 0.5 <f3 / f<1,0 0.6 <f3 / f<0,9 0.65 <f3 / f<0,8 where f is the focal length when focusing on an object at infinity, and f3 is the focal length of the third lens group.

[0048] In addition, favorable correction of aberrations becomes possible without increasing the number of lenses by making at least one surface within the first lens group and within the second lens group aspherical, which contributes to miniaturization and weight reduction of the imaging lens system.

[0049] In addition, it is preferable if the macro lens system satisfies the following conditional formula (6). Conditional formula (6) refers to the refractive power of the fourth lens group G4. If the refractive power of the fourth lens group G4 is not less than the lower limit of conditional formula (6), the refractive power of the fourth lens group G4 can be prevented from becoming too strong and variations in aberrations can be suppressed. In addition, if the refractive power of the fourth lens group G4 does not exceed the upper limit of conditional formula (6), the refractive power of the fourth lens group G4 can be prevented from becoming too weak and the range of movement during focusing operations can be reduced, resulting in a shortening of the overall length of the lens system. It should be noted that even more favorable characteristics can be obtained if conditional formula (6-1) is satisfied. 1.0 <f4 / f<2,0 1.1 <f4 / f<1,8 where f is the focal length when focusing on an object at infinity, and f4 is the focal length of the fourth lens group.

[0050] Additionally, it is preferable that the fourth lens group and the fifth lens group are moved toward the object side along their optical axes when focusing from an object at infinity to an object at a closest distance, and that the macro lens system satisfies the following conditional formula (7). Conditional formula (7) refers to the movement ranges of the fourth lens group G4 and the fifth lens group G5 during focusing operations. Axial chromatic aberrations can be favorably corrected if the movement ranges satisfy conditional formula (7). Note that even more favorable characteristics can be obtained if the movement ranges satisfy the following conditional formula (7-1), and more preferably, conditional formula (7-2). 0.7 <D4 / D5<1,5 0.8 <D4 / D5<1,3 0.9 <D4 / D5<1,1 where D4 denotes the amount of focusing movement of the fourth lens group from a state where an object at infinity is in focus to a state where an object at a closest distance is in focus, and D5 denotes the amount of focusing movement of the fifth lens group from a state where an object at infinity is in focus to a state where an object at a closest distance is in focus.

[0051] Furthermore, it is preferred if the fourth lens group has a cemented lens formed by a negative lens and a positive lens on the side closest to the object side. This allows for the effective correction of longitudinal chromatic aberrations (longitudinal chromatic aberrations) that arise when the object distance changes.

[0052] In this case, it is preferable if the macro lens system satisfies the following conditional formula (8). Conditional formula (8) refers to the Abbe numbers of the lenses constituting the cemented lens in the fourth lens group G4. Axial chromatic aberrations can be favorably corrected, from imaging an object at infinity to imaging an object at a closest distance, if the Abbe numbers of the lenses satisfy conditional formula (8). Note that even more favorable performance can be obtained if the Abbe numbers satisfy the following conditional formula (8-1), and more preferably, conditional formula (8-2). 20 <v4dp−v4dn 25 <v4dp−v4dn 30 <v4dp−v4dn where v4dp denotes the Abbe number of the positive lens forming the cemented lens of the fourth lens group with respect to the d-line and v4dn denotes the Abbe number of the negative lens forming the cemented lens of the fourth lens group with respect to the d-line.

[0053] It is preferable for the distance between the fourth lens group and the fifth lens group to increase and then decrease when focusing from an object at infinity to an object at a closest distance. This allows field curvature to be effectively corrected over the entire range from an object at infinity to an object at a closest distance.

[0054] Additionally, it is preferable if the fourth lens group has two positive lenses and if the macro lens system satisfies the following conditional formula (9). Conditional formula (9) refers to the Abbe number of the positive lenses of the fourth lens group G4. Axial chromatic aberrations and chromatic aberrations of magnification of objects at close distances can be favorably corrected if the Abbe numbers of the positive lenses of the fourth lens group G4 satisfy conditional formula (9). 60.0 <v4d where v4d is the average Abbe number of the positive lenses in the fourth lens group with respect to the d-line.

[0055] It is preferable that the total number of lenses constituting the lens groups that move during focusing operations is 7 or less. This can reduce the weight of the moving lenses, contributing to high-speed focusing operations.

[0056] In the present macro lens system, the specifically preferred material for placement closest to the object is glass. Alternatively, a transparent ceramic material can be used.

[0057] Additionally, if the present macro lens system is to be used in harsh environments, it is preferable to provide a multilayer protective coating film. Furthermore, in addition to the protective coating, an anti-reflection coating may be applied to reduce ghost light or the like during use.

[0058] In the Fig. In the example illustrated in Figure 1, the optical element PP is provided between the lens system and the imaging surface Sim. Alternatively, various filters, such as a low-pass filter or filters that cut off specific wavelength bands, can be provided between the lenses instead of between the lens system and the imaging surface Sim. As a further alternative, coatings that perform the same functions as the various filters can be applied to the surfaces of the lenses.

[0059] The following describes the numerical values ​​of examples of the macro lens system according to the present invention.

[0060] First, the macro lens system of Example 1 is described. Fig. 1 is a collection of sectional views illustrating the lens configuration of the macro lens system of Example 1, and Fig. Figure 2 is a diagram illustrating the movement trajectories of each lens group of the macro lens system of Example 1. It should be noted that the optical member PP in Fig. 1 and Fig. 2, as well as in the Fig. 3 to 10, which correspond to Examples 2 to 5 to be described later. In these drawings, the left side is the object side, the right side is the image side, and the aperture stops St illustrated therein do not necessarily represent their size or shape, but indicate the positions of the stops along the optical axis Z.

[0061] Basic lens data of the macro lens system of Example 1 are shown in Table 1, data related to various factors are shown in Table 2, data related to distances between the moving surfaces are shown in Table 3, and data related to aspherical coefficients are shown in Table 4. Below, the symbols in the tables are described with reference to those of Example 1. The same basically applies to tables related to Examples 2 to 5.

[0062] In the lens data of Table 1, surface numbers i (i=1, 2, 3, ...) that increase sequentially, with the object-most surface of the constituent elements being designated as 1, are listed in the Si column; the radii of curvature of the i-th surfaces are listed in the Ri column; and distances between an i-th surface and an (i+l)-th surface are listed in the Di column. In addition, refractive indices with respect to the d-line (wavelength: 587.6 nm) of the optical elements j (j=1, 2, 3, ...) that increase sequentially, with the object-most optical element being designated as 1, are listed in the Ndj column; and the Abbe numbers with respect to the d-line (wavelength: 587.6 nm) of the j-th optical elements are listed in the vdj column.

[0063] It should be noted that the signs of the radii of curvature are positive in cases where the surface shapes are convex toward the object side, and negative in cases where the surface shapes are concave toward the object side. The basic lens data also includes data regarding the aperture stop St and the optical element PP. The word (stop) is given along with the surface number in the row of column Si corresponding to the aperture stop St. In addition, DD[i] is given in the rows of column Di, which correspond to surface distances that change with magnification changes. In addition, the value in the bottom row of column Di indicates the distance between the image-side surface of the optical element PP and the imaging surface Sim.

[0064] Focal lengths f', back focus values ​​Bf', F-number F no. and full angles of view 2ω are listed for a condition when an object is imaged at infinity, for a condition when an object is imaged at a medium distance and for a condition when an object is imaged at a closest distance as the data regarding factors in Table 2.

[0065] In the basic lens data, the data regarding factors, and the data relating to the distances between the moving surfaces, degrees are used as the unit of angle and mm as the unit of length. However, since optical systems can be scaled and enlarged proportionally, other suitable units can be used.

[0066] In the lens data of Table 1, the "*" mark is added to surface numbers corresponding to aspherical surfaces, and the numerical values ​​of the paraxial (near-axis) curvature radii are listed as the curvature radii of the aspherical surfaces. The surface numbers Si of the aspherical surfaces and aspherical coefficients related to the aspherical surfaces are listed in Table 4 as the data related to aspherical coefficients. The aspherical coefficients are the values ​​of the coefficients KA and Am (m = 3, 4, 5, ..., 20) in the following aspherical formula (A). Zd=C⋅h2 / {1+(1−KA⋅C2⋅h2)1 / 2}+∑Am⋅hm where Zd represents the depth of the aspherical surface (the length of a line drawn from a point on the aspherical surface with a height h to a plane perpendicular to the optical axis contacting the vertex of the aspherical surface), h represents the height (the distance from the optical axis), C represents the inverse of the paraxial radius of curvature, and KA, Am represent aspherical coefficients (m = 3, 4, 5,..., 20). Table 1 Example 1: Lens data Si (surface number) Ri (radius of curvature) Di (surface distance) Ndj (refractive index) vdj (Abbezahl) 1 794,4933 1,26 1,84666 23,78 2 26,0420 4,85 1,59522 67,74 3 -60,5422 0,10 *4 23,5562 3,95 1,74330 49,33 5 -500,9101 DD(5) *6 -105,5377 1,10 1,73077 40,50 *7 19,2398 2,56 8 -46,3896 1,01 1,51680 64,20 9 23,6450 2,32 1,84666 23,78 10 64,7859 DD

[10] 11 67,7469 2,95 1,92286 20,88 12 -67,7469 2,67 13(Aperture) ∞ DD

[13] 14 -32,3230 1,02 1,74077 27,79 15 32,3230 4,55 1,59522 67,74 16 -27,4119 0,11 17 74,8635 2,92 1,61800 63,33 18 -74,8635 DD[18) 19 37,2563 3,07 1,72916 54,68 20 -674,5448 DD

[20] 21 -126,2001 1,01 1,69895 30,13 22 25,3759 2,75 23 -47,2254 1,33 1,51742 52,43 24 ∞ 1,48 25 297,4201 2,58 1,67003 47,23 26 -68,6822 1,00 27 ∞ 1,22 1,51680 64,20 28 ∞ 22,81 Table 2 Example 1 - Factors (d-line) β=0 β=-0,5 β=-0,98 f 51,52 Bf 24,62 FNo. 2,88 3,06 3,59 2ω[°] 30,6 22,4 13,8 Table 3 Example 1 - Group spacing DD[5] 1,60 5,25 9,61 DD

[10] 9,10 5,45 1,10 DD

[13] 12,68 6,82 2,47 DD

[18] 1,52 2,54 1,51 DD

[20] 1,85 6,69 12,08

[0067] Fig. 11 (A) to 11 (L) are diagrams illustrating each type of aberration of the macro lens system of Example 1. Fig.11(A) to 11(D) illustrate spherical aberration, astigmatism, distortion, and lateral chromatic aberration, respectively, in a state when imaging an object at infinity. Fig. 11(E) to 11(H) respectively illustrate spherical aberration, astigmatism, distortion and lateral chromatic aberration in a state when imaging an object at a medium distance. Fig. 11(I) to 11(L) respectively illustrate spherical aberration, astigmatism, distortion and lateral chromatic aberration in a state when imaging an object at a closest distance.

[0068] Aberrations with the d-line (wavelength: 587.6 nm) as a reference wavelength are illustrated in the diagrams illustrating spherical aberration, astigmatism, and distortion related to the d-line (wavelength: 587.6 nm), the C-line (wavelength: 656.3 nm), and the F-line (wavelength: 486.1 nm). These are indicated by solid lines, broken lines, and dotted lines in the diagrams illustrating spherical aberration, respectively. Aberrations in the sagittal and tangential directions are indicated by solid lines and dotted lines in the diagrams illustrating astigmatism. Aberrations related to the C line (wavelength: 656.3 nm) and the F line (wavelength: 486.1 nm) are indicated by dashed lines and dotted lines in the diagrams illustrating lateral chromatic aberrations, respectively. Note that in the diagrams illustrating spherical aberrations, "Fno" is used.“ denotes F-numbers, and, in the diagrams illustrating other types of aberrations, ω denotes half angles of view.

[0069] A macro lens system of Example 2 is described below. Fig. 3 is a collection of sectional diagrams illustrating the lens configuration of the macro lens system of Example 2 and Fig. Figure 5 is a diagram illustrating the motion trajectories of each lens group of the macro lens system of Example 2. Basic lens data of the macro lens system of Example 2 are shown in Table 5, data regarding various factors are shown in Table 6, data regarding distances between the moving surfaces are shown in Table 7, and data regarding aspherical coefficients are shown in Table 8. Fig. 12(A) to 12(L) are diagrams illustrating each type of aberration of the macro lens system of Example 2. Table 5 Example 2: Lens data Si (surface number) Ri (radius of curvature) Di (surface distance) Ndj (refractive index) vdj (Abbezahl) 1 325,115] 1,26 1,84666 23,78 2 25,0050 4,86 1,59522 67,74 3 -65,8502 0,10 *4 23,7023 3,94 1,74330 49,33 5 -477,1992 DD[5] *6 -110,0872 1,10 1,73077 40,50 *7 19,2308 2,51 8 -48,4057 1,09 1,51680 64,20 9 22,7850 2,29 1,84666 23,78 10 55,8224 DD

[10] 11 67,2447 2,95 1,92286 20,88 12 -67,2447 2,67 13(Aperture) ∞ DD

[13] 14 -32,9090 1,01 1,74077 27,79 15 32,9090 4,42 1,59522 67,74 16 -28,5899 0,10 17 68,8855 3,07 1,61800 63,33 18 -68,8855 DD

[18] 19 37,2563 3,05 1,72916 54,68 20 -869,7814 DD

[20] 21 -119,8966 1,00 1,69895 30,13 22 24,2116 2,74 23 -51,5043 1,20 1,51742 52,43 24 ∞ 1,50 25 285,7313 2,70 1,67003 47,23 26 -67,2064 1,00 27 ∞ 1,22 1,51680 64,20 28 ∞ 22,82 Table 6 Example 2 - Factors (d-line) β=0 β=-0,5 β=-0,98 f 51,53 Bf 24,63 FNo. 2,87 3,06 3,59 2ω[°] 30,6 22,2 13,6 Table 7 Example 2 - Group spacing DD[5] 1,60 5,22 9,54 DD

[10] 9,06 5,44 1,12 DD

[13] 12,78 6,78 2,42 DD

[18] 1,53 2,82 1,69 DD

[20] 1,84 6,55 12,04 Table 8

[0070] A macro lens system of Example 3 is described below. Fig. 5 is a collection of sectional diagrams illustrating the lens configuration of the macro lens system of Example 3 and Fig. 6 is a diagram illustrating the motion trajectories of each lens group of the macro lens system of Example 3. Basic lens data of the macro lens system of Example 3 are shown in Table 9, data regarding various factors are shown in Table 10, data relating to distances between the moving surfaces are shown in Table 10, and data relating to aspherical coefficients are shown in Table 11. Fig.13(A) to 13(L) are diagrams illustrating each type of aberration of the macro lens system of Example 3. Table 9 Example 3: Lens data Si (surface number) Ri (radius of curvature) Di (surface distance) Ndj (refractive index) vdj (Abbezahl) 1 1518,1285 1,26 1,84666 23,78 2 26,3136 6,50 1,59522 67,74 3 -53,5481 0,10 *4 24,7803 3,94 1,74330 49,33 5 -524,5779 DD[5] *6 -84,4894 1,10 1,73077 40,50 *7 19,9998 2,44 8 -42,9989 0,94 1,51680 64,20 9 26,1261 2,45 1,84666 23,78 10 103,2064 DD

[10] 11 76,4558 2,76 1,92286 20,88 12 -58,6881 2,87 13(Aperture) ∞ DD

[13] 14 -27,9922 0,96 1,74077 27,79 15 29,1623 4,17 1,59522 67,74 16 -27,0840 0,10 17 105,8903 2,45 1,61800 63,33 18 -50,4769 DD

[18] 19 38,6341 2,62 1,72916 54,68 20 -180,7987 DD

[20] 21 -113,0444 1,00 1,69895 30,13 22 25,3257 2,40 23 -38,0511 1,60 1,51742 52,43 24 -461,9100 1,97 25 -702,6803 2,65 1,66998 39,27 26 -52,4791 1,00 27 ∞ 1,22 1,51680 64,20 28 ∞ 23,31 Table 10 Example 3 - Factors (d-line) β=0 β=-0,5 β=-0,98 f 51,50 Bf 24,83 FNo. 2,87 3,32 3,82 2ω[°] 30,6 23,0 14,4 Table 11 Example 3 - Group spacing DD[5] 1,60 5,13 9,55 DD

[10] 9,00 5,47 1,05 DD

[13] 11,65 6,25 2,22 DD

[18] 1,71 2,45 1,46 DD

[20] 1,85 6,51 11,54

[0071] A macro lens system of Example 4 is described below. Fig. Figure 7 is a collection of sectional diagrams illustrating the lens configuration of the macro lens system of Example 4 and Fig.8 is a diagram illustrating the motion trajectories of each lens group of the macro lens system of Example 4. Basic lens data of the macro lens system of Example 4 are shown in Table 13, data regarding various factors are shown in Table 14, data relating to distances between the moving surfaces are shown in Table 15, and data relating to aspherical coefficients are shown in Table 16. Fig. 14(A) to 14(L) are diagrams illustrating each type of aberration of the macro lens system of Example 4. Table 13 Example 4: Lens data Si (surface number) Ri (radius of curvature) Di (surface distance) Ndj (refractive index) vdj (Abbezahl) 1 3572,1034 1,25 1,92286 18,90 2 31,1032 5,53 1,59522 67,74 3 -61,9607 0,10 *4 27,1630 4,23 1,80348 40,44 5 -151,2957 DD[5] 6 -77,4745 1,10 1,73077 40,50 *7 19,9999 2,44 8 -118,8541 0,94 1,51742 52,43 9 24,3828 2,30 2,00272 19,32 10 44,7941 DD

[10] 11 45,5422 3,05 1,95906 17,47 12 -176,2993 2,87 13(Aperture) ∞ DD[131 14 -42,6052 0,95 1,84666 23,78 15 26,7889 4,14 1,72916 54,68 16 -33,7470 0,25 17 109,0738 2,34 1,80400 46,58 18 -116,3258 DD

[18] 19 54,6146 2,80 2,00100 29,13 20 293,3249 DD

[20] 21 -85,7108 1,00 1,84666 23,78 22 24,0427 2,80 23 28,1094 3,01 1,83400 37,16 24 75,4021 1,00 25 ∞ 1,22 1,51680 64,20 26 ∞ 23,99 Table 14 Example 4 - Factors (d-line) β=0 β=-0,5 β=-0,98 f 51,51 Bf 25,51 FNo. 2,85 3,40 3,99 2ω[°] 30,8 20,8 12,6 Table 15 Example 4 - Group spacing DD[5] 1,60 5,97 10,37 DD

[10] 9,82 5,45 1,06 DD

[13] 12,75 7,45 2,21 DD

[18] 2,57 1,79 1,47 DD

[20] 1,55 7,63 13,19

[0072] A macro lens system of Example 5 is described below. Fig.9 is a collection of sectional diagrams illustrating the lens configuration of the macro lens system of Example 5 and Fig. 10 is a diagram illustrating the motion trajectories of each lens group of the macro lens system of Example 5. Basic lens data of the macro lens system of Example 5 are shown in Table 17, data regarding various factors are shown in Table 18, data relating to distances between the moving surfaces are shown in Table 19, and data relating to aspherical coefficients are shown in Table 20. Fig. 15(A) to 15(L) are diagrams illustrating each type of aberration of the macro lens system of Example 5. Table 17 Example 5: Lens data Si (surface number) Ri (radius of curvature) Di (surface distance) Ndj (refractive index) vdj (Abbezahl) 1 179,8497 1,25 1,92286 18,90 2 28,5480 5,56 1,59522 67,74 3 -58,7519 0,10 *4 25,3543 4,00 1,77250 49,47 5 -442,9125 DD[5] 6 -85,0581 1,10 1,83441 37,28 *7 20,0000 2,44 8 -77,2269 0,94 1,48749 70,23 9 22,9413 2,30 2,00272 19,32 10 41,1307 DD

[10] 11 44,8117 3,30 1,94595 17,98 12 -111,4703 2,87 13(Aperture) ∞ DD

[13] 14 -39,6602 0,95 1,84666 23,78 15 28,0205 3,82 1,69680 55,53 16 -42,7659 0,10 17 193,0801 2,51 1,88300 40,76 18 -51,9041 DD

[18] 19 50,9718 2,25 2,00100 29,13 20 262,2396 DD

[20] 21 -68,9635 1,00 1,84666 23,78 22 22,4570 2,12 23 25,2211 3,90 1,63854 55,38 24 200,0000 1,00 25 ∞ 1,22 1,51680 64,20 26 ∞ 23,56 Table 18 Example 5 - Factors (d-line) β=0 β=-0,5 β=-0,98 f 51,49 Bf 25,37 FNo. 2,87 3,40 3,98 2ω[°] 30,8 22,2 15,8 Table 19 Example 5 - Group spacing DD[5] 1,60 5,67 9,88 DD

[10] 9,36 5,29 1,08 DD

[13] 11,49 7,03 2,21 DD

[18] 4,66 2,62 1,46 DD

[20] 1,90 8,40 14,38

[0073] The values ​​of the macro lens systems of Examples 1 to 5 corresponding to the conditional formulas (1) to (9) are shown in the following Table 21. It should be noted that all of these examples use the d-line as a reference wavelength, and the values ​​given in Table 21 are obtained at this reference wavelength. Table 21 formula Condition Example 1 Example 2 Example 3 Example 4 Example 5 (1) N1d<1.60 1,59522 1,59522 1,59522 1,59522 1,59522 (2) 60.0 <v1d 67,7 67,7 67,7 67,7 67,7 (3) 25.0 <v2dn-v2dp 40,4 40,4 40,4 33,1 50,9 (4) v3d<30.0 20,9 20,9 20,9 17,5 18,0 (5) 0.5 <f3 / f<1,0 0,720 0,715 0,705 0,738 0,663 (6) 1.0 <f4 / f<2,0 1,368 1,286 1,560 1,388 1,393 (7) 0.7 <D4 / D5<1,5 0,998 1,016 0,976 0,907 0,745 (8) 20 <v4dp-v4dn 39,95 39,95 39,95 30,9 31,75 (9) 60.0 <v4d 65,6 65,6 65,6 50,7 48,2

[0074] The above data indicate that all of the macro lens systems of Examples 1 to 5 satisfy the conditional formulas (1) to (8). Furthermore, the macro lens systems of Examples 1 to 3 satisfy the conditional formula (9). This demonstrates that the macro lens systems of the examples are miniature macro lens systems capable of effectively correcting chromatic aberrations even when imaging objects at close distances.

[0075] An imaging device according to an embodiment of the present invention will be described below.Fig. 16 is a collection of diagrams illustrating the external appearance of an example of a mirrorless interchangeable lens camera using the macro lens system according to the embodiment of the present invention as an example of the imaging device according to the embodiment of the present invention.

[0076] Fig. 16A illustrates the external appearance of the camera seen from the front and Fig. Figure 16B illustrates the external appearance of the camera as viewed from the rear. This camera includes a camera body 10. A shutter button 32 and a power button 33 are provided on the upper surface of the camera body 10. A display section 36 and operation sections 34 and 35 are provided on the rear surface of the camera body 10. The display section 36 is used to display acquired images.

[0077] An imaging aperture, into which light from imaging targets enters, is provided in the central portion of the front surface of the camera body 10. A mount 37 is provided at the position corresponding to the imaging aperture. The mount 37 allows an interchangeable lens 20 to be attached to the camera body 10. The interchangeable lens 20 is a lens barrel in which lens elements are housed. An imaging element such as a CCD that outputs image signals corresponding to images of a subject formed by the interchangeable lens 20, a signal processing circuit that processes the image signals output from the imaging element to generate images, a recording medium for storing the formed images, etc., are provided within the camera body 10. In this camera, pressing the shutter button 32 causes a photographing operation of a single frame of a still image to be performed.The image data obtained by photography is stored in the recording medium (not shown) within the camera body 10.

[0078] When a macro lens system of the present embodiment is used as the interchangeable lens 20 of the mirrorless interchangeable-lens camera, the camera as a whole can be miniaturized. At the same time, high-quality images in which chromatic aberrations are favorably corrected even when imaging at close distances can be obtained.

[0079] The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above-mentioned embodiments and examples, and various modifications are possible. For example, the numerical values ​​of the radii of curvature, surface distances, refractive indices, Abbe numbers, etc. of the lens components are not limited to those exemplified in the above examples and may assume various values.

Claims

[1] Macro lens system consisting, in this order starting from one side of the object, of: a first lens group (G1) with a positive refractive power; a second lens group (G2) with a negative refractive power; a third lens group (G3) with a positive refractive power; a fourth lens group (G4) with a positive refractive power; a fifth lens group (G5) with a positive refractive power; and a sixth lens group (G6) with a negative refractive power; wherein the first lens group (G1) consists of three lenses; and the second lens group (G2), the fourth lens group (G4) and the fifth lens group (G5) are moved independently in the direction of their optical axes when focusing from an object at infinity to an object at a closest distance, and wherein the macro lens system satisfies the following conditional formula (5): 0.5 <f3 / f<1,0 where f is the focal length when focusing on an object at infinity, and f3 is the focal length of the third lens group (G3). [2] Macro lens system according to claim 1, wherein: the first lens group (G1), in this order starting from the object side, consists of a cemented lens consisting of a negative lens and a positive lens with a convex cemented surface, and a positive lens. [3] A macro lens system according to claim 1 or 2, wherein the first lens group (G1) comprises at least one positive lens; and at least one positive lens satisfies the following conditional formulas (1) and (2): N1d<1.60 60.0 <v1d where N1d denotes the refractive index of the positive lens in the first lens group (G1) with respect to the d-line and v1d denotes the Abbe number of the positive lens in the first lens group (G1) with respect to the d-line. [4] A macro lens system according to any one of claims 1 to 3, wherein the second lens group (G2) comprises a cemented lens formed by a negative lens and a positive lens, and satisfies the following conditional formula (3): 25.0 <v2dn−v2dp where v2dp denotes the Abbe number of the positive lens forming the cemented lens of the second lens group (G2) with respect to the d-line and v2dn denotes the Abbe number of the negative lens forming the cemented lens of the second lens group (G2) with respect to the d-line. [5] Macro lens system according to one of claims 1 to 4, wherein the third lens group (G3) is formed from a single positive lens and satisfies the following conditional formula (4): v3d<30.0 where v3d is the Abbe number with respect to the d-line of the positive lens of the third lens group (G3). [6] Macro lens system according to one of claims 1 to 5, wherein at least one surface within the first lens group (G1) is aspherical. [7] Macro lens system according to one of claims 1 to 6, wherein at least one surface within the second lens group (G2) is aspherical. [8] Macro lens system according to one of claims 1 to 7, wherein the macro lens system satisfies the following conditional formula (6): 1.0 <f4 / f<2,0 where f is the focal length when focusing on an object at infinity, and f4 is the focal length of the fourth lens group (G4). [9] Macro lens system according to one of claims 1 to 8, wherein: the fourth lens group (G4) and the fifth lens group (G5) when focusing from an object at infinity to an object at a closest distance, along whose optical axes are moved toward the object side; and the macro lens system satisfies the following conditional formula (7): 0.7 <D4 / D5<1,5 where D4 denotes the amount of focusing movement of the fourth lens group (G4) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus, and D5 denotes the amount of focusing movement of the fifth lens group (G5) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus. [10] Macro lens system according to one of claims 1 to 9, wherein: the fourth lens group (G4) has a cemented lens on the side closest to the object side, which is formed by a negative lens and a positive lens. [11] A macro lens system according to claim 10, wherein: the macro lens system satisfies the following conditional formula (8): 20 <v4dp−v4dn where v4dp denotes the Abbe number of the positive lens forming the cemented lens of the fourth lens group (G4) with respect to the d-line and v4dn denotes the Abbe number of the negative lens forming the cemented lens of the fourth lens group (G4) with respect to the d-line. [12] A macro lens system according to any one of claims 1 to 11, wherein the distance between the fourth lens group (G4) and the fifth lens group (G5) increases, then decreases, when focusing from an object at infinity to an object at a closest distance. [13] Macro lens system according to one of claims 1 to 12, wherein: the fourth lens group (G4) has two positive lenses; and the macro lens system satisfies the following conditional formula (9): 60.0 <v4d where v4d is the average Abbe number of the positive lenses in the fourth lens group (G4) with respect to the d-line. [14] A macro lens system according to any one of claims 1 to 13, wherein: the total number of lenses constituting the lens groups that move during focusing operations is 7 or less. [15] Macro lens system according to one of claims 1 to 14, wherein: the first lens group (G1) comprises at least one positive lens; and at least one positive lens satisfies the following conditional formulas (1) and (2-1): N1d<1.60 65.0 <v1d where N1d denotes the refractive index of the positive lens in the first lens group (G1) with respect to the d-line and v1d denotes the Abbe number of the positive lens in the first lens group (G1) with respect to the d-line. [16] Macro lens system according to one of claims 1 to 15, wherein the second lens group (G2) comprises a cemented lens formed by a negative lens and a positive lens, and satisfies the following conditional formula (3-1): 30.0 <v2dn−v2dp where v2dp denotes the Abbe number of the positive lens forming the cemented lens of the second lens group (G2) with respect to the d-line and v2dn denotes the Abbe number of the negative lens forming the cemented lens of the second lens group (G2) with respect to the d-line. [17] A macro lens system according to any one of claims 1 to 16, wherein the third lens group (G3) is formed of a single positive lens and satisfies the following conditional formula (4-1): v3d<25.0 where v3d is the Abbe number with respect to the d-line of the positive lens of the third lens group (G3). [18] A macro lens system according to any one of claims 1 to 17, wherein the macro lens system satisfies the following conditional formula (5-1): 0.6 <f3 / f<0,9 where f is the focal length when focusing on an object at infinity, and f3 is the focal length of the third lens group (G3). [19] A macro lens system according to any one of claims 1 to 18, wherein the macro lens system satisfies the following conditional formula (5-2): 0.65 <f3 / f<0,8 where f is the focal length when focusing on an object at infinity, and f3 is the focal length of the third lens group (G3). [20] A macro lens system according to any one of claims 1 to 19, wherein the macro lens system satisfies the following conditional formula (6-1): 1.1 <f4 / f<1,8 where f is the focal length when focusing on an object at infinity, and f4 is the focal length of the fourth lens group (G4). [21] Macro lens system according to one of claims 1 to 20, wherein: the fourth lens group (G4) and the fifth lens group (G5) when focusing from an object at infinity to an object at a closest distance, along whose optical axes are moved toward the object side; and the macro lens system satisfies the following conditional formula (7-1): 0.8 <D4 / D5<1,3 where D4 denotes the amount of focusing movement of the fourth lens group (G4) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus, and D5 denotes the amount of focusing movement of the fifth lens group (G5) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus. [22] Macro lens system according to one of claims 1 to 21, wherein: the fourth lens group (G4) and the fifth lens group (G5) when focusing from an object at infinity to an object at a closest distance, along whose optical axes are moved toward the object side; and the macro lens system satisfies the following conditional formula (7-2): 0.9 <D4 / D5<1,1 where D4 denotes the amount of focusing movement of the fourth lens group (G4) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus, and D5 denotes the amount of focusing movement of the fifth lens group (G5) from a state in which an object at infinity is in focus to a state in which an object at a closest distance is in focus. [23] A macro lens system according to claim 10, wherein: the macro lens system satisfies the following conditional formula (8-1): 25 <v4dp−v4dn where v24p denotes the Abbe number with respect to the d-line of the positive lens forming the cemented lens of the fourth lens group (G4), and v4dn denotes the Abbe number with respect to the d-line of the negative lens forming the cemented lens of the fourth lens group (G4). [24] A macro lens system according to claim 10, wherein: the macro lens system satisfies the following conditional formula (8-2): 30 <v4dp−v4dn where v24p denotes the Abbe number with respect to the d-line of the positive lens forming the cemented lens of the fourth lens group (G4), and v4dn denotes the Abbe number with respect to the d-line of the negative lens forming the cemented lens of the fourth lens group (G4). [25] Imaging device comprising: a macro lens system according to any one of claims 1 to 24.

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