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

Abstract

The invention, 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

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and particularly to an ultra-large aperture medium-short focal length lens for M43 format. Background Art

[0002] In recent years, the multi-shooting functions of single-lens reflex cameras, mirrorless cameras, and compact cameras, which form the main body of the short camera camp, have been mostly replaced by mobile phones. However, for photography enthusiasts or imaging workers with higher photography requirements, mirrorless cameras and lenses can better utilize the performance of optical equipment, meet more comprehensive, multi-color, background blur, soft out-of-focus imaging and other requirements, and bring perfect photographic pleasure. Mirrorless cameras have the advantages of small size, light weight, convenient to carry, larger image plane and aperture, etc., and are still important shooting tools for professional studios and photography enthusiasts. Cameras represented by the M43 format are one of them.

[0003] Existing ultra-large aperture medium-short focal length lenses have problems of various aberrations that are difficult to perfectly correct and low resolution in the visible light region. Moreover, most of the existing traditional ultra-large aperture medium-short focal length lenses do not have an autofocus function. The problem lies in that the focusing components inside the lens are heavy, and the load of the motor used to drive the focusing components to move to meet the requirements of fast autofocus is large, making it difficult to meet the fast focusing design requirements of ultra-large aperture lenses. Currently, there is no autofocus lens with an aperture smaller than F#1.0 (F# is the focal length of the lens divided by the aperture diameter) on the market. Summary of the Invention

[0004] In view of the deficiencies of the existing technology and market demands, the present invention provides an ultra-large aperture medium-short focal length lens for M43 format, which is small in size and light in weight. The internal focusing component can be composed of only one lens, and it has the characteristics of fast focusing speed and excellent imaging performance, and is applicable to the M43 format optical imaging system.

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

[0006] An ultra-large aperture medium-short focal length lens for M43 format, comprising a first lens group, a second lens group, a third lens group, and a fourth lens group arranged in sequence along the optical axis from the object side to the image side; the focal lengths of all lens groups satisfy the following conditional expressions:

[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] Among them, 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 lens group, the second lens group and the third lens group, and F represents the combined focal length of all lens groups;

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

[0013] Further, 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 in sequence from the object side to the image side along the optical axis;

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

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

[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 a convex surface facing the object side;

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

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

[0022] The eighth lens is a biconcave lens;

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

[0024] The tenth lens is a biconvex lens.

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

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

[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 conditional formula:

[0031] 0.15 < S3 / S < 0.4;

[0032] wherein, S3 is the distance from the intersection of the optical axis on 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 large-aperture medium short-focus lens with an M43 format is 0.9 - 1.2.

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

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

[0037] The technical solution of the present invention has the following advantages: In the large-aperture medium short-focus lens with an M43 format, the third lens group as the focusing component is only composed of one lens, which reduces the weight of the focusing group and the load of the driving motor, is conducive to the rapid focusing of the large-aperture medium short-focus lens and the imaging device, and can meet the design requirements of the autofocus lens. Moreover, this large-aperture medium short-focus lens corrects various aberrations in each wavelength band, enabling sufficient resolution in both the central and peripheral fields of view. It has the advantages of simple structure, small volume, and large aperture, and can achieve high-resolution imaging from infinity to close range. Moreover, through the reasonable distribution of the optical power, the present invention ensures the shooting brightness of the picture while having a super large aperture of 0.95. Description of the Drawings

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 It is a schematic cross-sectional structure diagram of the large-aperture medium short-focus lens with an M43 format in the first example of the present invention;

[0040] Figure 2This is the spherical aberration diagram of the M43 format ultra-large aperture medium short-focus lens in Example 1 of the present invention when the object distance is infinite;

[0041] Figure 3 This is the field curvature and distortion diagram of the M43 format ultra-large aperture medium short-focus lens in Example 1 of the present invention when the object distance is infinite;

[0042] Figure 4 This is the cross-sectional structure schematic diagram of the M43 format ultra-large aperture medium short-focus lens in Example 2 of the present invention;

[0043] Figure 5 This is the spherical aberration diagram of the M43 format ultra-large aperture medium short-focus lens in Example 2 of the present invention when the object distance is infinite;

[0044] Figure 6 This is the field curvature and distortion diagram of the M43 format ultra-large aperture medium short-focus lens in Example 2 of the present invention when the object distance is infinite.

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

[0046] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0048] Such as Figure 1 - Figure 6An ultra-large aperture medium-short focal length lens with an M43 format, including 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.

[0049] The focal lengths of all lens groups satisfy the following conditional expressions:

[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] Among them, 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. Among them, the third lens group G3 includes only one lens, and the third lens group G3 moves along the optical axis direction to achieve focusing.

[0055] This ultra-large aperture medium-short focal length lens with an M43 format, as the focusing component, the third lens group is composed of only one lens, which reduces the weight of the focusing group and the load of the driving motor, is beneficial to the quick focusing of the ultra-large aperture medium-short focal length lens and the imaging device, and can meet the design requirements of the autofocus lens. Moreover, this ultra-large aperture medium-short focal length lens corrects various aberrations in each wavelength band, enabling sufficient resolution in both the central and peripheral fields of view. It has the advantages of simple structure, small volume, and large aperture, and can achieve high resolution for imaging from infinity to close range of the object distance. Moreover, through the reasonable distribution of the optical power, the present invention ensures the shooting brightness of the picture while having an ultra-large aperture of 0.95.

[0056] It should be noted that the M43 format, also known as Micro Four Thirds, is a camera sensor specification. This specification defines the interface standard between the lens and the camera sensor and uses an image sensor with a size of 17.3mm x 13.0mm, whose diagonal length is approximately 21.6mm. This size is exactly half of the diagonal length of a 35mm full-frame sensor, so it is also called the "Four Thirds" system because its aspect ratio is 4:3, different from the 3:2 aspect ratio of traditional 35mm film cameras. Due to the use of a smaller sensor in the M43 system, M43 lenses are usually smaller and lighter than DSLR cameras and their lenses. An ultra-large aperture generally refers to a very large aperture opening in a camera lens to allow more light to enter the camera sensor. The size of the aperture is usually represented by the ratio of the focal length to the aperture diameter F# (f / D). The smaller the F# value, the larger the aperture. Generally speaking, a lens with an aperture value greater than F / 2 can be considered a large-aperture lens, and an ultra-large aperture lens refers to a lens with a maximum aperture value reaching or less than F / 1.2. For example, a lens with F / 0.95 is considered an ultra-large aperture lens. Medium and short focal length lenses usually refer to those lenses that are neither ultra-wide-angle nor telephoto. Generally, a short focal length lens usually refers to a lens with a focal length below 35mm. For example, a lens with a focal length of 14 - 24mm is a short focal length lens; a medium focal length lens usually refers to a lens with a focal length approximately between 50mm and 100mm. Therefore, the focal length range of the "medium and short focal length lens" in this application can be generally understood as between 14mm and 100mm.

[0057] Among them, 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 along the optical axis from the object side to the image side. 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, and the seventh lens L7 is a negative focal length lens with a 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 in sequence 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 focal length lens with a convex surface facing the image side, and the tenth lens L10 is a biconvex lens.

[0059] The third lens group G3 only includes an eleventh lens L11, and the eleventh lens L11 is a meniscus lens with a convex surface facing the object side. The third lens group G3 moves along the optical axis direction to achieve focusing.

[0060] The fourth lens group G4 includes a twelfth lens L12, a thirteenth lens L13, and a fourteenth lens L14, which are arranged in sequence 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 conditional formula: 0.15 < S3 / S < 0.4. Wherein, 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 and the optical axis to the image surface when focused at infinity.

[0062] As a preferred solution, 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 solution, the aperture of the super-large aperture medium-short focal length lens in the M43 format is 0.9 - 1.2. The focal length range of the super-large aperture medium-short focal length lens in the M43 format is 15 mm - 35 mm.

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

[0065] In the first example of the present invention, the relevant parameters of each lens are shown in Tables 1-1, 1-2, and 1-3 as follows:

[0066]

[0067]

[0068] Table 1-1

[0069]

[0070] Table 1-2

[0071]

[0072] Table 1-3

[0073] In the second example of the present invention, the relevant parameters of each lens are shown in Tables 2-1, 2-2, and 2-3 as follows:

[0074]

[0075]

[0076] Table 2-1

[0077]

[0078] Table 2-2

[0079]

[0080] Table 2-3 The data of Example 1 and Example 2 of the present invention are as shown in Table 3 below:

[0081] Conditional 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

[0082] Table 3

[0083] As Figure 1 shown, in the embodiment of the present invention, the eleventh lens L11 can move along the optical axis between the tenth lens L10 and the twelfth lens L12 for focusing. Since the eleventh lens L11 performs internal focusing, the overall length of the lens can be kept unchanged when the lens adjusts the focal length.

[0084] This M43 format ultra-large aperture medium-short focal length lens corrects various aberrations in each wavelength band, enabling sufficient resolution in both the central and peripheral fields of view. It has the advantages of simple structure, small size, and large aperture, and can achieve high resolution for imaging with object distances ranging from infinity to close range.

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

[0086] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. An M43 format ultra-large aperture medium-short focal length lens, characterized in that: The invention comprises a first lens group (G1), a second lens group (G2), a third lens group (G3), and a fourth lens group (G4) which are 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 formula: 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; Wherein, 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) includes only 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 focal length 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) which are arranged in sequence from the object side to the image side along the optical axis; The first lens (L1) is a positive power lens with a convex surface facing the object side; The second lens (L2) is a negative power lens with a 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 a convex surface facing the object side; The seventh lens (L7) is a negative refractive power lens with a concave surface facing the image side.

3. The M43 format ultra-large aperture medium-short focal length 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) which are sequentially arranged 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 a convex surface facing the image side; The tenth lens (L10) is a biconvex lens.

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

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

2.

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

10. The M43 format ultra-large aperture medium-short focal length 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