Short-focus full-frame lens

Abstract

The short-focus full-frame lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged from an object side to an image side along an optical axis, the focal lengths of all the lens groups meet the following conditional expressions: 0.5 < f (G1) / f < 1.5; f (G2) / f (G3) is greater than-1.5 and less than-0.5; f (G1) / f (G3) is more than 0.3 and less than 0.9; wherein 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, and f represents the combined focal length of all the lens groups. According to the short-focus full-frame lens, various aberrations of various wave bands are corrected, the central view field and the edge view field have enough resolution, the short-focus full-frame lens has the advantages of being simple in structure, small in size and large in aperture, and the high resolution of imaging of the object distance from infinity to close distance can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and particularly to a short-focus full-frame lens. Background Art

[0002] In recent years, although the multi-functions of mobile phones have replaced the daily photography of compact cameras, for photography enthusiasts with higher photography requirements, mirrorless cameras can better experience perfect photography pleasure. Mirrorless camera lenses have the advantages of small size, light weight, convenient to carry, larger image plane and aperture, etc., and can experience better background blur effect. In addition, compared with crop-frame cameras, full-frame camera lenses can produce better image quality and richer expression of picture content.

[0003] Existing short-focus full-frame lenses have problems of various aberrations and low resolution in imaging some wavelength bands. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects that existing short-focus full-frame lenses have various aberrations and low resolution in imaging some wavelength bands, so as to provide a short-focus full-frame lens.

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

[0006] A short-focus full-frame lens includes a first lens group, a second lens group, and a third lens group that are sequentially arranged 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] 0.5 < f(G1) / f < 1.5;

[0008] -1.5 < f(G2) / f(G3) < -0.5;

[0009] 0.3 < f(G1) / f(G3) < 0.9;

[0010] Wherein, 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, and f represents the combined focal length of all lens groups.

[0011] Further, a diaphragm is provided between the first lens group and the second lens group, and the second lens group can move along the direction of the optical axis to achieve focusing.

[0012] 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;

[0013] The first lens is a biconcave lens with negative optical power;

[0014] The second lens is a biconvex lens with positive optical power;

[0015] The third lens is a meniscus lens with negative optical power and its convex surface facing the image side;

[0016] The fourth lens is a meniscus lens with negative optical power and its convex surface facing the object side;

[0017] The fifth lens is a biconvex lens with positive optical power;

[0018] The sixth lens is a plano - concave meniscus lens with negative optical power, the seventh lens is a plano - convex lens with positive optical power, the object side surface of the sixth lens facing the object side is a plane, and the image side surface of the seventh lens facing the image side is a plane;

[0019] Or, the sixth lens is a biconcave lens with negative optical power or a meniscus lens with negative optical power and its convex surface facing the object side; the seventh lens is a biconvex lens with positive optical power or a meniscus lens with positive optical power and its convex surface facing the object side;

[0020] Wherein, one adjacent surface of the second lens and the third lens is glued together; one adjacent surface of the fourth lens and the fifth lens is glued together; one adjacent surface of the sixth lens and the seventh lens is glued together.

[0021] Further, the second lens group includes an eighth lens; the eighth lens is a meniscus lens with negative optical power and its convex surface facing the object side.

[0022] Further, the third lens group includes a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens;

[0023] The ninth lens is a biconvex lens with positive optical power;

[0024] The tenth lens is a meniscus lens with negative optical power and its convex surface facing the object side;

[0025] The eleventh lens is a biconvex lens with positive optical power;

[0026] The twelfth lens is a biconcave lens with negative optical power;

[0027] Wherein, one adjacent surface of the eleventh lens and the twelfth lens is glued together.

[0028] Further, the object side surface of the second lens is an aspherical surface, the object side surface and the image side surface of the eighth lens are both aspherical surfaces, and the object side surface of the eleventh lens is an aspherical surface; the two side surfaces of the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the ninth lens, the tenth lens, and the twelfth lens are both spherical surfaces.

[0029] Further, the aperture of the short-focus full-frame lens is 1 - 1.6, the focal length of the short-focus full-frame lens is 20 - 40 mm, and the field angle 2ω of the short-focus full-frame lens is 55° - 75°.

[0030] Further, the overall optical length of the short-focus full-frame lens does not exceed 115 mm.

[0031] The technical solution of the present invention has the following advantages: The short-focus full-frame 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 with object distances ranging from infinity to close range. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 also be obtained based on these drawings.

[0033] Figure 1 It is a schematic cross-sectional structure diagram of the short-focus full-frame lens in the embodiment of the present invention;

[0034] Figure 2 It is the field curvature and distortion diagram of the short-focus full-frame lens in the embodiment of the present invention.

[0035] Description of the reference numerals: G1, the first lens group; G2, the second lens group; G3, the third lens group; G4, the fourth lens group; 1, the first lens; 2, the second lens; 3, the third lens; 4, the fourth lens; 5, the fifth lens; 6, the sixth lens; 7, the seventh lens; 8, the eighth lens; 9, the ninth lens; 10, the tenth lens; 11, the eleventh lens; 12, the twelfth lens. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The following will clearly and completely describe the technical solution of the present invention in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0037] 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 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 should not 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.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] As Figure 1 shown, a short-focus full-frame lens includes a first lens group G1, a second lens group G2, and a third lens group G3 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:

[0040] 0.5 < f(G1) / f < 1.5;

[0041] -1.5 < f(G2) / f(G3) < -0.5;

[0042] 0.3 < f(G1) / f(G3) < 0.9;

[0043] 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, and f represents the combined focal length of all lens groups.

[0044] In this embodiment, the first lens group G1 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, and a seventh lens 7 arranged in sequence along the optical axis from the object side to the image side. The first lens 1 is a biconcave lens with negative optical power; the second lens 2 is a biconvex lens with positive optical power; the third lens 3 is a meniscus lens with negative optical power and its convex surface facing the image side; the fourth lens 4 is a meniscus lens with negative optical power and its convex surface facing the object side; the fifth lens 5 is a biconvex lens with positive optical power; the sixth lens 6 is a plano-concave meniscus lens with negative optical power; the seventh lens 7 is a plano-convex lens with positive optical power. The object side surface of the sixth lens 6 facing the object side is a plane, and the image side surface of the seventh lens 7 facing the image side is a plane. The object side surface of the sixth lens 6 and the image side surface of the seventh lens 7 can also be convex or concave surfaces with a very large radius of curvature. For example, the sixth lens 6 can also be a biconcave lens with negative optical power or a meniscus lens with negative optical power and its convex surface facing the object side; the seventh lens 7 can also be a biconvex lens with positive optical power or a meniscus lens with positive optical power and its convex surface facing the object side.

[0045] The second lens group G2 includes an eighth lens 8, and the eighth lens 8 is a meniscus lens with negative optical power and its convex surface facing the object side.

[0046] The third lens group G3 includes a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged in sequence along the optical axis from the object side to the image side. The ninth lens 9 is a biconvex lens with positive optical power; the tenth lens 10 is a meniscus lens with negative optical power and its convex surface facing the object side, the eleventh lens 11 is a biconvex lens with positive optical power, and the twelfth lens 12 is a biconcave lens with negative optical power.

[0047] In this embodiment, a diaphragm is provided between the first lens group G1 and the second lens group G2. The second lens group G2 can move along the direction of the optical axis to achieve focusing. The second lens group G2 has only a single eighth lens 8 for the focusing function, and the focusing is more convenient and simple.

[0048] In this embodiment, the two side surfaces of the first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the ninth lens 9, the tenth lens 10, and the twelfth lens 12 are all spherical surfaces. The object side surface of the second lens 2 facing the object side is an aspherical surface, and the image side surface of the second lens 2 facing the image side is a spherical surface; the object side surface and the image side surface of the eighth lens 8 facing the object side and the image side are both aspherical surfaces; the object side surface of the eleventh lens 11 facing the object side is an aspherical surface, and the image side surface of the eleventh lens 11 facing the image side is a spherical surface; with such a setting, spherical aberration, field curvature and other aberrations can be effectively corrected, and the overall weight of the lens can be reduced.

[0049] Furthermore, one side of the second lens 3 and the third lens 3 adjacent to each other is glued together; one side of the fourth lens 4 and the fifth lens 5 adjacent to each other is glued together; one side of the sixth lens 6 and the seventh lens 7 adjacent to each other is glued together; one side of the eleventh lens 11 and the twelfth lens 12 adjacent to each other is glued together. The glued lens combination can effectively correct chromatic aberration and make the colors of the captured images more realistic.

[0050] Among them, the relevant parameters of each lens are shown in Table 1 below:

[0051] Lens Surface shape Radius R (mm) Thickness D (mm) Refractive index Nd Abbe number Vd First lens Spherical surface －146.195 1.68 1.506 60.33 Spherical surface 28.584 16.27 Second lens Aspherical surface 175.121 10.00 1.772 33.04 Third lens Spherical surface －35.919 1.40 1.707 30.22 Spherical surface －65.790 10.88 Fourth lens Spherical surface 117.163 1.40 1.733 24.02 Fifth lens Spherical surface 46.623 10.36 1.648 85.29 Spherical surface －46.658 0.16 Sixth lens Spherical surface infinity 1.13 1.735 23.43 Seventh lens Spherical surface 37.243 5.24 1.955 28.17 Spherical surface infinity 0.60 Diaphragm Spherical surface infinity 2.21 Eighth lens Aspherical surface 167.190 1.27 1.633 47.40 Aspherical surface 23.605 10.94 Ninth lens Spherical surface 23.290 9.12 1.703 73.96 Spherical surface －50.017 0.88 Tenth lens Spherical surface infinity 1.60 1.595 51.24 Spherical surface 43.946 2.06 Eleventh lens Aspherical surface 62.312 7.71 1.697 55.22 Twelfth lens Spherical surface －25.345 1.29 1.723 24.90 Spherical surface 31.719 20.20

[0052] Table 1

[0053] As Figure 1 shown, in the embodiment of the present invention, the eighth lens 8 can perform internal focusing between the seventh lens 7 and the ninth lens 9 along the optical axis direction. Therefore, when the lens adjusts the focal length, the overall length of the lens can be kept unchanged.

[0054] This short-focus full-frame 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.

[0055] From Figure 2 it can be seen that the field curvatures of the short-focus full-frame lens in the meridional direction (corresponding to T in Figure 2 ) and the sagittal direction (corresponding to S in Figure 2 ) of the light rays are between -0.2 mm and 0.2 mm; the maximum distortion of the crop-frame lens is within 10%.

[0056] It should be noted that this short-focus full-frame 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 with a bayonet that matches various brands of cameras on the market according to actual usage requirements to achieve personalized customization and general compatibility.

[0057] 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 enumerate 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. A short-focus full-frame lens, characterized in that, It includes a first lens group (G1), a second lens group (G2), and a third lens group (G3) 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: 0.5 < f(G1) / f < 1.5; -1.5 < f(G2) / f(G3) < -0.5; 0.3 < f(G1) / f(G3) < 0.9; 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), and f represents the combined focal length of all lens groups.

2. The short-focus full-frame lens according to claim 1, characterized in that There is a diaphragm between the first lens group (G1) and the second lens group (G2), and the second lens group (G2) can move along the direction of the optical axis to achieve focusing.

3. The short-focus full-frame lens according to claim 1, wherein The first lens group (G1) includes a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens (6), and a seventh lens (7); The first lens (1) is a biconcave lens with negative optical power; The second lens (2) is a biconvex lens with positive optical power; The third lens (3) is a meniscus lens with negative optical power and its convex surface facing the image side; The fourth lens (4) is a meniscus lens with negative optical power and its convex surface facing the object side; The fifth lens (5) is a biconvex lens with positive optical power; The sixth lens (6) is a plano-concave meniscus lens with negative optical power, the seventh lens (7) is a plano-convex lens with positive optical power, the object side surface of the sixth lens (6) facing the object side is a plane, and the image side surface of the seventh lens (7) facing the image side is a plane; Or, the sixth lens (6) is a biconcave lens with negative optical power or a meniscus lens with negative optical power and its convex surface facing the object side; the seventh lens (7) is a biconvex lens with positive optical power or a meniscus lens with positive optical power and its convex surface facing the object side; wherein, the adjacent surfaces of the second lens (2) and the third lens (3) are glued together; the adjacent surfaces of the fourth lens (4) and the fifth lens (5) are glued together; the adjacent surfaces of the sixth lens (6) and the seventh lens (7) are glued together.

4. The short-focus full-frame lens according to claim 3, characterized in that, The second lens group (G2) includes an eighth lens (8); the eighth lens (8) is a meniscus lens with negative optical power and its convex surface facing the object side.

5. The short-focus full-frame lens according to claim 4, wherein The third lens group (G3) includes a ninth lens (9), a tenth lens (10), an eleventh lens (11), and a twelfth lens (12); The ninth lens (9) is a biconvex lens with positive optical power; The tenth lens (10) is a meniscus lens with negative optical power and its convex surface facing the object side; The eleventh lens (11) is a biconvex lens with positive optical power; The twelfth lens (12) is a biconcave lens with negative optical power; wherein, the adjacent surfaces of the eleventh lens (11) and the twelfth lens (12) are glued together.

6. The short-focus full-frame lens according to claim 5, wherein, The object side surface of the second lens (2) facing the object side is an aspherical surface, and both the object side surface of the eighth lens (8) facing the object side and the image side surface facing the image side are aspherical surfaces; the object side surface of the eleventh lens (11) facing the object side is an aspherical surface; both side surfaces of the first lens (1), the third lens (3), the fourth lens (4), the fifth lens (5), the sixth lens (6), the seventh lens (7), the ninth lens (9), the tenth lens (10), and the twelfth lens (12) are spherical surfaces.

7. The short-focus full-frame lens according to claim 1, characterized in that, The aperture of the short focal length full-frame lens is 1 - 1.6, the focal length of the short focal length full-frame lens is 20 - 40 mm, and the field angle 2ω of the short focal length full-frame lens is 55° - 75°.

8. The short-focus full-frame lens according to claim 1, wherein The overall optical length of the short focal length full-frame lens does not exceed 115 mm.

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