M43-format ultra-large-aperture medium-short-focus lens

Abstract

The utility model, which belongs to the technical field of the optical lens, discloses an M43-format ultra-large-aperture medium-short-focus lens comprising a first lens group, a second lens group, a third lens group, and a fourth lens group which are successively arranged from the object side to the image side along the optical axis. The focal lengths of all the lens groups satisfy the following conditional expressions: 3 < f (G1) / F < 5; f (G3) / F is greater than-4 and less than-2; f (G2) / f (G4) is more than 0.5 and less than 0.9; and 0.4 < f (G4) / f (G1-G3) < 1.5. The focusing assembly of the ultra-large aperture medium-short focus lens is only composed of one lens, so that the weight of a focusing group and the load of a pushing motor are reduced, rapid focusing of the lens and imaging equipment is facilitated, and the design requirement of automatic focusing is met; the lens corrects various aberrations of various wavebands, enables the central and edge fields of view to have enough resolution, has the advantages of simple structure, small size and large aperture, and can realize imaging of an object distance from infinity to close distance.

Description

A medium-short telephoto lens with a large aperture for Micro Four Thirds sensor. Technical Field

[0001] This invention relates to the field of optical lens technology, specifically to a large aperture medium-short focal length lens for Micro Four Thirds (M43) sensors. Background Technology

[0002] In recent years, the multi-shot functions of cameras, primarily consisting of DSLRs, mirrorless cameras, and point-and-shoot cameras, have been largely replaced by smartphones. However, for photography enthusiasts or professionals with higher demands, mirrorless cameras and lenses can better utilize the performance of optical equipment, meeting needs for more comprehensive, multi-color, background blur, and soft bokeh, thus delivering a perfect photographic experience. Mirrorless cameras, with their advantages of small size, light weight, portability, larger image sensor, and larger aperture, remain important tools for professional studios and photography enthusiasts; cameras with Micro Four Thirds (M43) sensors are one such example.

[0003] Existing super-large aperture medium-short focal length lenses suffer from various aberrations that are difficult to correct perfectly in the visible light region, resulting in low resolution. Moreover, most existing traditional super-large aperture medium-short focal length lenses lack autofocus functionality. The problem lies in the fact that the focusing components inside the lens are relatively heavy, and the motors used to drive the focusing components to achieve the fast autofocus requirement are under a heavy load, making it difficult to meet the fast focusing design requirements of super-large aperture lenses. Currently, there are no autofocus lenses with an aperture smaller than F#1.0 (F# is the lens focal length divided by the aperture diameter) available on the market. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies and market demands by providing a large-aperture medium-short focal length lens for Micro Four Thirds (M43) cameras. It is small and lightweight, and its internal focusing mechanism consists of only one lens. It features fast focusing speed and excellent imaging performance and is suitable for Micro Four Thirds optical imaging systems.

[0005] To solve the above-mentioned technical problems, the technical solution of this invention is as follows:

[0006] A medium-short telephoto lens with a large aperture for Micro Four Thirds (M43) sensor includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially along the optical axis from the object side to the image side; the focal lengths of all lens groups satisfy the following condition:

[0007] 3 < f(G1) / F < 5;

[0008] -4 < f(G3) / F < -2;

[0009] 0.5 < f(G2) / f(G4) < 0.9;

[0010] 0.4<f(G4) / f(G1-G3)<1.5;

[0011] Where f(G1) represents the focal length of the first lens group, f(G2) represents the focal length of the second lens group, f(G3) represents the focal length of the third lens group, f(G4) represents the focal length of the fourth lens group, f(G1-G3) represents the combined focal length of the first, second and third lens groups, and F represents the combined focal length of all lens groups.

[0012] The third lens group comprises only one lens; the third lens group moves along the direction of the optical axis to achieve focusing.

[0013] Furthermore, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially along the optical axis from the object side to the image side;

[0014] The first lens is a positive power lens with its convex surface facing the object side;

[0015] The second lens is a negative power lens with its concave surface facing the image plane;

[0016] The third lens is a biconcave lens;

[0017] The fourth lens is a biconvex lens;

[0018] The fifth lens is a biconvex lens;

[0019] The sixth lens is a positive power lens with its convex surface facing the object side;

[0020] The seventh lens is a negative power lens with its concave surface facing the image side.

[0021] Furthermore, the second lens group includes an eighth lens, a ninth lens, and a tenth lens arranged sequentially along the optical axis from the object side to the image side;

[0022] The eighth lens is a biconcave lens;

[0023] The ninth lens is a positive power lens with its convex surface facing the image side;

[0024] The tenth lens is a biconvex lens.

[0025] Furthermore, the third lens group includes an eleventh lens, which is a meniscus lens with its convex surface facing the object side.

[0026] Furthermore, the fourth lens group includes a twelfth lens, a thirteenth lens, and a fourteenth lens arranged sequentially along the optical axis from the object side to the image side;

[0027] The twelfth lens is a biconvex lens;

[0028] The thirteenth lens is a biconvex lens;

[0029] The fourteenth lens is a biconcave lens.

[0030] Furthermore, the distance between the twelfth lens and the first lens satisfies the following condition:

[0031] 0.15 < S3 / S < 0.4;

[0032] Where S3 is the distance from the intersection of the optical axis of the object side of the twelfth lens to the image plane when focusing at infinity, and S is the distance from the intersection of the object side of the first lens and the optical axis to the image plane when focusing at infinity.

[0033] Furthermore, the first lens, the sixth lens, and the thirteenth lens are all optical lenses with a refractive index higher than 1.9.

[0034] Furthermore, the aperture of the ultra-large aperture short focal length lens in the M43 format is 0.9-1.2.

[0035] Furthermore, the focal length range of the M43 format ultra-large aperture medium-short telephoto lens is 15mm-35mm.

[0036] Furthermore, the fifth, tenth, and eleventh lenses are all aspherical lenses.

[0037] This novel technical solution has the following advantages: The third lens group, serving as the focusing assembly in this M43 format ultra-large aperture medium-short focal length lens, consists of only one lens, reducing the weight of the focusing assembly and the load on the drive motor. This facilitates rapid focusing of the ultra-large aperture medium-short focal length lens and the imaging device, meeting the design requirements of autofocus lenses. Furthermore, this ultra-large aperture medium-short focal length lens corrects various aberrations across different wavelengths, ensuring sufficient resolution in both the center and edge fields of view. It boasts advantages such as simple structure, small size, and large aperture, enabling high-resolution imaging from infinity to near distances. Moreover, through the rational allocation of optical power, this novel design maintains image brightness while possessing an ultra-large aperture of f / 0.95. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the specific embodiments of this invention or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 is a schematic diagram of the cross-sectional structure of the M43 format ultra-large aperture medium-short focal length lens in Example 1 of this novel invention;

[0040] Figure 2 shows the spherical aberration diagram of the M43 format ultra-large aperture medium-short focal length lens in Example 1 of this novel when the object distance is at infinity.

[0041] Figure 3 shows the field curvature distortion of the M43 format ultra-large aperture medium-short focal length lens in Example 1 of this novel when the object distance is infinitely far.

[0042] Figure 4 is a schematic diagram of the cross-sectional structure of the M43 format ultra-large aperture medium-short focal length lens in Example 2 of this novel invention;

[0043] Figure 5 shows the spherical aberration diagram of the M43 format ultra-large aperture medium-short focal length lens in Example 2 of this novel when the object distance is at infinity.

[0044] Figure 6 shows the field curvature distortion of the M43 format ultra-large aperture short focal length lens in Example 2 of this novel design at infinity object distance.

[0045] Explanation of reference numerals in the attached diagram: G1, first lens group; G2, second lens group; G3, third lens group; G4, fourth lens group; L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, eleventh lens; L12, twelfth lens; L13, thirteenth lens; L14, fourteenth lens. Detailed Implementation

[0046] The technical solution of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0047] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] As shown in Figures 1-6, a medium-short focal length lens with a large aperture for a Micro Four Thirds sensor includes a first lens group G1, a second lens group G2, a third lens group G3, and a fourth lens group G4 arranged sequentially along the optical axis from the object side to the image side.

[0049] The focal length of all lens groups satisfies the following condition:

[0050] 3 < f(G1) / F < 5;

[0051] -4 < f(G3) / F < -2;

[0052] 0.5 < f(G2) / f(G4) < 0.9;

[0053] 0.4<f(G4) / f(G1-G3)<1.5;

[0054] Where f(G1) represents the focal length of the first lens group G1, f(G2) represents the focal length of the second lens group G2, f(G3) represents the focal length of the third lens group G3, f(G4) represents the focal length of the fourth lens group G4, f(G1-G3) represents the combined focal length of the first lens group G1, the second lens group G2, and the third lens group G3, and F represents the combined focal length of all lens groups. The third lens group G3 consists of only one lens, and it moves along the optical axis to achieve focusing.

[0055] This M43 format ultra-large aperture medium-short telephoto lens, with its third lens group consisting of only one lens, reduces the weight of the focusing assembly and the load on the drive motor. This facilitates rapid focusing for both the ultra-large aperture medium-short telephoto lens and the imaging device, meeting the design requirements of autofocus lenses. Furthermore, this ultra-large aperture medium-short telephoto lens corrects various aberrations across different wavelengths, ensuring sufficient resolution in both the center and peripheral fields of view. It boasts advantages such as simple structure, small size, and large aperture, enabling high-resolution imaging from infinity to near distances. Moreover, through the rational allocation of optical power, this new design maintains image brightness while possessing an ultra-large aperture of f / 0.95.

[0056] It's important to note that M43, short for Micro Four Thirds, is a camera sensor specification. This specification defines the interface standard between the lens and the camera sensor, and uses a 17.3mm x 13.0mm image sensor with a diagonal length of approximately 21.6mm. This size is exactly half the diagonal length of a 35mm full-frame sensor, hence the name "4:3" system because of its 4:3 aspect ratio, unlike the 3:2 ratio of traditional 35mm film cameras. Due to the smaller sensor used, M43 lenses are typically smaller and lighter than SLR cameras and their lenses. A large aperture usually refers to a camera lens capable of achieving a very large aperture opening, allowing more light to enter the camera sensor. Aperture size is usually expressed as the ratio of focal length to aperture diameter, F# (f / D); the smaller the F# value, the larger the aperture. Generally speaking, lenses with an aperture value greater than F / 2 are considered large-aperture lenses, while ultra-large-aperture lenses refer to lenses with a maximum aperture value of F / 1.2 or less. For example, a lens with an F / 0.95 is considered an ultra-large-aperture lens. Medium-short telephoto lenses typically refer to lenses that are neither ultra-wide-angle nor telephoto. Generally, short telephoto lenses refer to lenses with a focal length of 35mm or less, such as lenses with a focal length of 14-24mm; medium telephoto lenses typically refer to lenses with a focal length approximately between 50mm and 100mm. Therefore, the focal length range of "medium-short telephoto lenses" in this application can be roughly understood as between 14mm and 100mm.

[0057] The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged sequentially along the optical axis from the object side to the image side. The first lens L1 is a positive power lens with its convex surface facing the object side, the second lens L2 is a negative power lens with its concave surface facing the image plane, the third lens L3 is a biconcave lens, the fourth lens L4 is a biconvex lens, the fifth lens L5 is a biconvex lens, the sixth lens L6 is a positive power lens with its convex surface facing the object side, and the seventh lens L7 is a negative power lens with its concave surface facing the image side.

[0058] The second lens group G2 includes an eighth lens L8, a ninth lens L9, and a tenth lens L10 arranged sequentially along the optical axis from the object side to the image side. The eighth lens L8 is a biconcave lens, the ninth lens L9 is a positive power lens with its convex surface facing the image side, and the tenth lens L10 is a biconvex lens.

[0059] The third lens group G3 consists of only one eleventh lens L11, which is a meniscus lens with its convex surface facing the object side. The third lens group G3 moves along the optical axis to achieve focusing.

[0060] The fourth lens group G4 includes a twelfth lens L12, a thirteenth lens L13, and a fourteenth lens L14 arranged sequentially along the optical axis from the object side to the image side. The twelfth lens L12 is a biconvex lens, the thirteenth lens L13 is a biconvex lens, and the fourteenth lens L14 is a biconcave lens.

[0061] In this embodiment, the distance between the twelfth lens L12 and the first lens L1 satisfies the following condition: 0.15 < S3 / S < 0.4. Wherein, S3 is the distance from the intersection of the optical axis of the object side of the twelfth lens L12 to the image plane when focusing at infinity, and S is the distance from the intersection of the object side of the first lens L1 and the optical axis to the image plane when focusing at infinity.

[0062] As a preferred option, the first lens L1, the sixth lens L6, and the thirteenth lens L13 are all optical lenses with a refractive index higher than 1.9.

[0063] As a preferred option, the aperture of a large-aperture medium-short telephoto lens for the Micro Four Thirds format is f / 0.9–1.2. The focal length range of a large-aperture medium-short telephoto lens for the Micro Four Thirds format is 15mm–35mm.

[0064] As a preferred option, the fifth lens L5, the tenth lens L10, and the eleventh lens L11 are all aspherical lenses.

[0065] In this novel example, the relevant parameters of each lens are shown in Tables 1-1, 1-2, and 1-3 below:

[0066]

[0067]

[0068] Table 1-1

[0069]

[0070] Table 1-2

[0071]

[0072] Table 1-3

[0073] In Example 2 of this novel invention, the relevant parameters of each lens are shown in Tables 2-1, 2-2, and 2-3 below:

[0074]

[0075]

[0076] Table 2-1

[0077]

[0078] Table 2-2

[0079]

[0080] Table 2-3 shows the data for Examples 1 and 2 of this invention, as shown in Table 3 below:

[0081] Example 1 Example 2 f(G1) / F 4.40 4.29 f(G3) / F-3.44-2.45 f(G2) / f(G4) 0.71 0.79 f(G4) / f(G1-G3) 1.14 0.73 S3 / S 0.25 0.30 surface

[0082] Table 3

[0083] As shown in Figure 1, in this novel embodiment, the eleventh lens L11 can move along the optical axis between the tenth lens L10 and the twelfth lens L12 for focusing. Because the eleventh lens L11 focuses internally, the overall length of the lens remains constant when adjusting the focal length.

[0084] This type of M43 format ultra-large aperture medium-short telephoto lens corrects various aberrations in different wavelengths, ensuring sufficient resolution in both the center and edge fields of view. It has the advantages of simple structure, small size, and large aperture, and can achieve high resolution imaging from infinity to close distance.

[0085] It should be noted that this ultra-large aperture medium-short focal length lens adopts an integrated design, achieving lens miniaturization while obtaining excellent optical performance such as high resolution, low breathing, and low distortion at a very cost-effective price. It can be designed to match the lens mounts of various brands of cameras on the market according to actual usage needs, so as to achieve personalized customization and universal compatibility.

[0086] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A large-aperture medium-short telephoto lens for Micro Four Thirds (M43) format, characterized in that... It includes a first lens group (G1), a second lens group (G2), a third lens group (G3), and a fourth lens group (G4) arranged in sequence from the object side to the image side along the optical axis; the focal lengths of all lens groups satisfy the following conditional expressions: 3 < f(G1) / F < 5; -4 < f(G3) / F < -2; 0.5 < f(G2) / f(G4) < 0.9; 0.4 < f(G4) / f(G1 - G3) < 1.5; where f(G1) represents the focal length of the first lens group (G1), f(G2) represents the focal length of the second lens group (G2), f(G3) represents the focal length of the third lens group (G3), f(G4) represents the focal length of the fourth lens group (G4), f(G1 - G3) represents the combined focal length of the first lens group (G1), the second lens group (G2), and the third lens group (G3), and F represents the combined focal length of all lens groups; the third lens group (G3) only includes one lens; the third lens group (G3) moves along the direction of the optical axis to achieve focusing.

2. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The first lens group (G1) includes a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6), and a seventh lens (L7) arranged in sequence from the object side to the image side along the optical axis; the first lens (L1) is a positive focal length lens with a convex surface facing the object side; the second lens (L2) is a negative focal length lens with a concave surface facing the image side; the third lens (L3) is a biconcave lens; the fourth lens (L4) is a biconvex lens; the fifth lens (L5) is a biconvex lens; the sixth lens (L6) is a positive focal length lens with a convex surface facing the object side; the seventh lens (L7) is a negative focal length lens with a concave surface facing the image side.

3. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The second lens group (G2) includes an eighth lens (L8), a ninth lens (L9), and a tenth lens (L10) arranged in sequence from the object side to the image side along the optical axis; the eighth lens (L8) is a biconcave lens; the ninth lens (L9) is a positive focal length lens with a convex surface facing the image side; the tenth lens (L10) is a biconvex lens.

4. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The third lens group (G3) includes an eleventh lens (L11), and the eleventh lens (L11) is a meniscus lens with a convex surface facing the object side.

5. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The fourth lens group (G4) includes a twelfth lens (L12), a thirteenth lens (L13), and a fourteenth lens (L14) arranged in sequence from the object side to the image side along the optical axis; the twelfth lens (L12) is a biconvex lens; the thirteenth lens (L13) is a biconvex lens; the fourteenth lens (L14) is a biconcave lens.

6. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The distance between the twelfth lens (L12) and the first lens (L1) satisfies the following conditional expression: 0.15 < S3 / S < 0.4; where S3 is the distance from the intersection of the optical axis of the object side surface of the twelfth lens (L12) to the image surface when focused at infinity, and S is the distance from the intersection of the object side surface of the first lens (L1) with the optical axis to the image surface when focused at infinity.

7. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The first lens (L1), the sixth lens (L6), and the thirteenth lens (L13) are all optical lenses with a refractive index higher than 1.

9.

8. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The aperture of the ultra-large aperture short focal length lens in the M43 format is 0.9-1.

2.

9. The M43 format ultra-large aperture medium-short telephoto lens according to claim 1, characterized in that, The focal length range of the M43 format ultra-large aperture medium-short telephoto lens is 15mm-35mm.

10. The M43 format ultra-large aperture medium-short telephoto lens according to claim 5, characterized in that, The fifth lens (L5), the tenth lens (L10), and the eleventh lens (L11) are all aspherical lenses.

Images