Prime lens and camera

Abstract

The invention discloses a prime lens and a camera, and relates to the technical field of prime lenses, the prime lens is provided with an object side and an image side which are oppositely arranged along the optical axis direction, the prime lens comprises a first lens group, a second lens group, a third lens group and a fourth lens group which are sequentially arranged from the object side to the image side, and the four lens groups comprise eleven lenses, the first lens, the fourth lens, the seventh lens, the eighth lens and the tenth lens have positive focal power; the second lens, the third lens, the fifth lens, the sixth lens, the ninth lens and the eleventh lens have negative focal power; wherein the third lens group is movably arranged along the extension direction of the optical axis and is used for focusing, so that the aperture number of the prime lens is adjustable in a range of 1.6-2.0, the variation range of a field angle is less than 5%, and the distortion degree of the prime lens is less than 3%. According to the technical scheme provided by the invention, the technical effects of large aperture and stable imaging are achieved through the arrangement and combination of the eleven lenses and the design of the lenses.

Description

Technical Field

[0001] This invention relates to the field of fixed-focus lens technology, and particularly to a fixed-focus lens and a camera. Background Technology

[0002] With the rapid development of social media platforms and the popularity of short video content, more and more users are inclined to record and share their daily lives by shooting vlogs. This trend has spurred increased demand for high-performance, portable photography equipment, especially action cameras that are easy to carry and operate without compromising image quality. Video bloggers not only pursue high-quality still images but also pay special attention to the expressiveness and stability of video content to ensure viewers have the best viewing experience. A large aperture allows more light to enter, shortening exposure time and resulting in stable and reliable images, as well as a shallower depth of field. Therefore, designing a large-aperture, image-stabilized camera lens is particularly important. Summary of the Invention

[0003] The main objective of this invention is to provide a fixed-focus lens and camera, which aims to offer a fixed-focus lens with a large aperture and stable imaging.

[0004] To achieve the above objectives, the present invention proposes a fixed-focus lens, which has an object side and an image side arranged opposite each other along the optical axis. The fixed-focus lens includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side. In the direction from the object side to the image side, the first lens group sequentially includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; the second lens group sequentially includes a sixth lens and a seventh lens; the third lens group sequentially includes an eighth lens, a ninth lens, and a tenth lens; and the fourth lens group includes an eleventh lens. The lens comprises: a first lens, a fourth lens, a seventh lens, an eighth lens, and a tenth lens having positive optical power; and a second lens, a third lens, a fifth lens, a sixth lens, a ninth lens, and an eleventh lens having negative optical power. The third lens group is movably arranged along the extension direction of the optical axis for focusing, such that the aperture number of the fixed-focus lens is adjustable within a range greater than or equal to 1.6 and less than or equal to 2.0, the change range of the field of view is less than or equal to 5% of the initial field of view, and the distortion degree of the fixed-focus lens is less than 3%.

[0005] In one embodiment, the total optical length of the fixed-focus lens is TTL, where TTL ≤ 65mm.

[0006] In one embodiment, the focal length of the fixed-focus lens is F, where F = 43mm; The focal length of the first lens is f1, where 35mm ≤ f1 ≤ 50mm; The focal length of the second lens is f2, -55mm≤f2≤-40mm; The focal length of the third lens is f3, -55mm≤f3≤-40mm; The focal length of the fourth lens is f4, where 25mm ≤ f4 ≤ 40mm; The focal length of the fifth lens is f5, -90mm≤f5≤-70mm; The focal length of the sixth lens is f6, -80mm≤f6≤-60mm; The focal length of the seventh lens is f7, -80mm≤f7≤-60mm; The focal length of the eighth lens is f8, where 20mm ≤ f8 ≤ 35mm; The focal length of the ninth lens is f9, -40mm≤f9≤-25mm; The focal length of the tenth lens is f10, 210mm≤f10≤280mm; The focal length of the eleventh lens is f11, -50mm≤f11≤-35mm.

[0007] In one embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the seventh lens, the eighth lens, the ninth lens, and the eleventh lens are all configured as spherical lenses; Both the sixth lens and the tenth lens are configured as aspherical lenses.

[0008] In one embodiment, the first lens is cemented to the second lens, the fourth lens is cemented to the fifth lens, and the eighth lens is cemented to the ninth lens.

[0009] In one embodiment, the Abbe number of the first lens is V1, where 45.0 ≤ v1 ≤ 70.0; The Abbe number of the second lens is V2, where 25.0 ≤ v2 ≤ 45.0; The Abbe number of the third lens is V3, where 40.0 ≤ v3 ≤ 65.0; The Abbe number of the fourth lens is V4, where 55.0 ≤ v4 ≤ 95.0; The Abbe number of the fifth lens is V5, where 30.0 ≤ v5 ≤ 45.0; The Abbe number of the sixth lens is V6, where 35.0 ≤ v6 ≤ 50.0; The Abbe number of the seventh lens is V7, where 40.0 ≤ v7 ≤ 65.0; The Abbe number of the eighth lens is V8, where 50.0 ≤ v8 ≤ 95.0; The Abbe number of the ninth lens is V9, where 25.0 ≤ v9 ≤ 45.0; The Abbe number of the tenth lens is V10, where 45.0 ≤ v10 ≤ 95.0; The Abbe number of the eleventh lens is V11, where 30.0 ≤ v11 ≤ 55.0.

[0010] In one embodiment, the refractive index of the first lens is N1, where 1.60 ≤ n1 ≤ 1.75; The refractive index of the second lens is N2, 1.60≤n2≤1.80; The refractive index of the third lens is N3, where 1.50 ≤ n3 ≤ 1.70; The refractive index of the fourth lens is N4, where 1.50 ≤ n4 ≤ 1.70; The refractive index of the fifth lens is N5, where 1.60 ≤ n5 ≤ 1.80; The refractive index of the sixth lens is N6, where 1.70 ≤ n6 ≤ 1.95; The refractive index of the seventh lens is N7, where 1.60 ≤ n7 ≤ 1.75; The refractive index of the eighth lens is N8, where 1.65 ≤ n8 ≤ 1.80; The refractive index of the ninth lens is N9, where 1.55 ≤ n9 ≤ 1.70; The refractive index of the tenth lens is N10, where 1.45 ≤ n10 ≤ 1.65; The refractive index of the eleventh lens is N11, where 1.55 ≤ n11 ≤ 1.75.

[0011] In one embodiment, the diameter D1 of the first lens satisfies: D1 < 26 mm; The image plane diameter IC of the fixed-focus lens satisfies: IC≤29.5mm.

[0012] In one embodiment, the fixed-focus lens further includes: An aperture stop, wherein the aperture stop is disposed between the first lens group and the second lens group; and, The photosensitive chip is located on the image side of the fourth lens group; A filter is disposed between the photosensitive chip and the fourth lens.

[0013] The present invention also proposes a camera, the camera including a fixed-focus lens, the fixed-focus lens having an object side and an image side arranged opposite to each other along the optical axis, the fixed-focus lens including a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side; the first lens group, the third lens group, the fifth lens group, and the seventh lens group have positive optical power, and the second lens group, the fourth lens group, and the sixth lens group have negative optical power; wherein, the third lens group is movably arranged along the extension direction of the optical axis for focusing, so that the aperture number of the fixed-focus lens is adjustable within the range of greater than or equal to 1.6 and less than or equal to 2.0, the change range of the field of view is less than or equal to 5% of the initial field of view, and the distortion degree of the fixed-focus lens is less than 3%.

[0014] The technical solution of this invention achieves the technical effect of having a large aperture and stable imaging by setting eleven lenses, arranging and designing the lenses. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of an embodiment of the fixed-focus lens provided by the present invention; Figure 2 for Figure 1 A schematic diagram of the spherical aberration curve for a medium focal length lens; Figure 3 for Figure 1 A schematic diagram of the vertical chromatic aberration curve of a medium focal length lens; Figure 4 for Figure 1 A schematic diagram of field curvature distortion in a medium prime lens.

[0017] Explanation of icon numbers: 100. Fixed-focus lens; 1. First lens group; 11. First lens; 12. Second lens; 13. Third lens; 14. Fourth lens; 15. Fifth lens; 2. Second lens group; 21. Sixth lens; 22. Seventh lens; 3. Third lens group; 31. Eighth lens; 32. Ninth lens; 33. Tenth lens; 4. Fourth lens group; 41. Eleventh lens; 5. Aperture stop; 6. Image sensor; 7. Filter.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] With the rapid development of social media platforms and the popularity of short video content, more and more users are inclined to record and share their daily lives by shooting vlogs. This trend has spurred increased demand for high-performance, portable photography equipment, especially action cameras that are easy to carry and operate without compromising image quality. Video bloggers not only pursue high-quality still images but also pay special attention to the expressiveness and stability of video content to ensure viewers have the best viewing experience. A large aperture allows more light to enter, shortening exposure time and resulting in stable and reliable images, as well as a shallower depth of field. Therefore, designing a large-aperture, image-stabilized camera lens is particularly important.

[0023] This invention proposes a fixed-focus lens.

[0024] Please see Figure 1In one embodiment of the present invention, the fixed-focus lens 100 has an object side and an image side arranged opposite to each other along the optical axis. The fixed-focus lens 100 includes a first lens group 1, a second lens group 2, a third lens group 3, and a fourth lens group 4 arranged sequentially from the object side to the image side. In the direction from the object side to the image side, the first lens group 1 is provided with a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, and a fifth lens 15; the second lens group 2 is provided with a sixth lens 21 and a seventh lens 22; the third lens group 3 is provided with an eighth lens 31, a ninth lens 32, and a tenth lens 33; and the fourth lens group 4 is provided with an eleventh lens 4. 1; The first lens 11, the fourth lens 14, the seventh lens 22, the eighth lens 31, and the tenth lens 33 have positive optical power; the second lens 12, the third lens 13, the fifth lens 15, the sixth lens 21, the ninth lens 32, and the eleventh lens 41 have negative optical power; wherein, the third lens group 3 is movably arranged along the extension direction of the optical axis for focusing, so that the aperture number of the fixed-focus lens 100 is adjustable within the range of greater than or equal to 1.6 and less than or equal to 2.0, the change range of the field of view is less than or equal to 5% of the initial field of view, and the distortion degree of the fixed-focus lens 100 is less than 3%.

[0025] The technical solution of this invention aims to counteract the field of view shift caused by lens group displacement during focusing, thus avoiding the "focus breathing effect." It's important to understand that the field of view (FOV) is determined by both the lens's focal length and image size: FOV = 2 × arctan(image half-width / focal length). During focusing, if the lens's effective focal length changes due to lens displacement, it directly leads to a field of view shift. Therefore, the core of achieving a stable field of view is to ensure that the lens's effective focal length remains essentially constant during focusing, or to control the change in field of view to within 5% (a range imperceptible to the human eye). In this embodiment, a lens group located in the middle position is moved for focusing. This middle lens group is in a "balanced position" between the front and rear lens groups, where the effects of displacement on the equivalent focal length cancel each other out, minimizing the change in field of view. Driving the third lens group 3 only moves three lenses, reducing the focusing load and counteracting the focal length shift through the "neutral position" of the middle group, making it a preferred method for achieving low focus breathing in professional lenses. The allocation of optical power not only affects aberration correction but also directly determines focal length stability during focusing. This design's optical power configuration (alternating positive and negative optical power) implicitly incorporates the logic of "stable field of view": The optical power configuration of the third lens group 3—combining the positive optical power of the eighth lens 31, the negative optical power of the ninth lens 32, and the positive optical power of the tenth lens 33—forms a "converging-diverging-converging" refractive path. When focusing, shifting this group allows the light refraction angles of the front and rear groups to compensate for each other, avoiding significant changes in the equivalent focal length. The optical power constraint between the front and rear groups: The first lens group 1 (5 elements, including 3 with negative optical power) and the fourth lens group 4 (1 with negative optical power) form a "front-rear constraint," fixing the overall optical baseline of the lens and limiting focal length fluctuations during focusing in the middle group to a small range (≤5%). This design approach not only meets the large aperture requirements of this lens (F1.6-F2.0) but also solves the pain point of "composition shift during focusing." This prime lens 100 achieves core advantages such as "large aperture (F1.6-F2.0) + low distortion (<3%) + stable field of view (change ≤5%)" through its "11 elements in 4 groups" lens configuration, scientific optical power distribution, and a third lens group with 3 movable focusing design. It is suitable for photography scenarios with high requirements for image quality, low light performance, and composition stability, such as professional portrait photography, night scene photography, and indoor documentary photography.

[0026] In order to make the fixed-focus lens 100 small, light and portable, the total optical length of the fixed-focus lens 100 is TTL, and TTL≤65mm.

[0027] To achieve the set focal length parameters for the fixed-focus lens 100, the focal length of each lens needs to be set. The focal length of the fixed-focus lens 100 is F, where F = 43mm; the focal length of the first lens 11 is f1, where f1 ≤ f1 ≤ 50mm; the focal length of the second lens 12 is f2, where -55mm ≤ f2 ≤ -40mm; the focal length of the third lens 13 is f3, where -55mm ≤ f3 ≤ -40mm; the focal length of the fourth lens 14 is f4, where f4 ≤ f4 ≤ 40mm; and the focal length of the fifth lens 15 is f5, where f5 ≤ f2 ≤ -90mm. m≤f5≤-70mm; the focal length of the sixth lens 21 is f6, -80mm≤f6≤-60mm; the focal length of the seventh lens is f7, -80mm≤f7≤-60mm; the focal length of the eighth lens 31 is f8, 20mm≤f8≤35mm; the focal length of the ninth lens 32 is f9, -40mm≤f9≤-25mm; the focal length of the tenth lens 33 is f10, 210mm≤f10≤280mm; the focal length of the eleventh lens 41 is f11, -50mm≤f11≤-35mm.

[0028] To meet the core technical requirements of large aperture, low distortion, and stable field of view, and to balance production practicality and cost, achieving the "optimal solution for performance and cost-effectiveness," in one embodiment, the first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15, the seventh lens 22, the eighth lens 31, the ninth lens 32, and the eleventh lens 41 are all configured as spherical lenses; the sixth lens 21 and the tenth lens 33 are both configured as aspherical lenses.

[0029] The role of spherical lenses is as follows: 1. To construct the basic refractive framework of the lens; 2. Spherical lens technology is mature, mass-producible, and cost-controllable; 3. To play the role of "auxiliary aberration correction". For the design of aspherical lenses: On the one hand, they can focus on correcting "spherical aberration": The core problem of large apertures (F1.6-F2.0) is "higher-order spherical aberration"—spherical lenses cause light rays at the lens edges to converge closer than those at the center, resulting in blurred edges and reduced sharpness. The sixth lens 21 and the tenth lens 33, as aspherical lenses, can optimize surface curvature (such as a gentle curvature in the central area and a gradual curvature in the edge area) to allow edge and central light rays to converge precisely at the same point, completely solving the spherical aberration problem at large apertures; on the other hand, they assist in correcting "field curvature and distortion": Field curvature is the problem of "the center and edges of the image not being sharp simultaneously", and distortion is the problem of "distorted object shapes". Aspherical lenses can compensate for the refraction error of light at the edge of the image by adjusting the surface contour. Combined with the basic correction of spherical lenses, they can ultimately achieve a low distortion effect of less than 3%. In addition, in this embodiment, two aspherical lenses can replace the correction effect of three to five spherical lenses. In the compact structure of "11 elements in 4 groups", image quality at a large aperture is guaranteed while controlling the size and weight of the lens.

[0030] To meet the requirements of large aperture and stable field of view, the first lens 11 and the second lens 12 are cemented together: the lenses with positive and negative optical powers are cemented together and located at the front of the lens, which is responsible for correcting "axial chromatic aberration" (the focus of light of different wavelengths shifts along the optical axis) - axial chromatic aberration under large aperture will cause the sharpness of the center and edge of the image to be inconsistent. This cementing can suppress chromatic aberration from the light incident source and lay the foundation for the aberration correction of the subsequent lens group; The fourth lens 14 and the fifth lens 15 are cemented together: the lenses with positive and negative optical powers are cemented together and located at the end of the first lens group 1, close to the aperture unit, and are responsible for correcting "lateral chromatic aberration" (the shift in the projection position of different wavelengths of light at the edge of the image) - lateral chromatic aberration will cause color shift at the edge of the image. With the aberration correction of the aspherical lens, the color purity at the edge of the image can be ensured under a large aperture. The eighth lens 31 and the ninth lens 32 are cemented together: the lenses with positive and negative optical power are cemented together and located in the third lens group 3, which is responsible for correcting the "chromatic aberration fluctuation during the focusing process" - when the focusing group is translated, the incident angle of light will change, which may cause the chromatic aberration to reappear. This cementing can dynamically compensate for this fluctuation, ensuring that the chromatic aberration is always controlled within the allowable range when focusing at close and long distances. At the same time, in line with the requirement of stable field of view (change ≤5%), the consistency of the image is improved.

[0031] To accurately correct chromatic aberration, balance refractive power and dispersion control, and ensure consistent imaging across all scenarios, the Abbe number of the first lens 11 is V1, 45.0 ≤ v1 ≤ 70.0; the Abbe number of the second lens 12 is V2, 25.0 ≤ v2 ≤ 45.0; the Abbe number of the third lens 13 is V3, 40.0 ≤ v3 ≤ 65.0; the Abbe number of the fourth lens 14 is V4, 55.0 ≤ v4 ≤ 95.0; and the Abbe number of the fifth lens 15 is V5, 30.0 ≤ v5 ≤ 45. 0; the Abbe number of the sixth lens 21 is V6, 35.0≤v6≤50.0; the Abbe number of the seventh lens 22 is V7, 40.0≤v7≤65.0; the Abbe number of the eighth lens 31 is V8, 50.0≤v8≤95.0; the Abbe number of the ninth lens 32 is V9, 25.0≤v9≤45.0; the Abbe number of the tenth lens 33 is V10, 45.0≤v10≤95.0; the Abbe number of the eleventh lens 41 is V11, 30.0≤v11≤55.0.

[0032] To ensure that the fixed-focus lens 100 meets the intended usage requirements in terms of comprehensive performance in terms of aberration, chromatic aberration, thermal stability, manufacturing feasibility, weight, size, and field of view, the refractive index of each lens within the fixed-focus lens 100 needs to be limited: the refractive index of the first lens 11 is N1, 1.60≤n1≤1.75; the refractive index of the second lens 12 is N2, 1.60≤n2≤1.80; the refractive index of the third lens 13 is N3, 1.50≤n3≤1.70; the refractive index of the fourth lens 14 is N4, 1.50≤n4≤1.70; the refractive index of the fifth lens 15 is N5, 1.60≤n5≤1.80; and the refractive index of the sixth lens 14 is N5, 1.60≤n5≤1.80. The refractive index of lens 21 is N6, 1.70≤n6≤1.95; the refractive index of the seventh lens 22 is N7, 1.60≤n7≤1.75; the refractive index of the eighth lens 31 is N8, 1.65≤n8≤1.80; the refractive index of the ninth lens 32 is N9, 1.55≤n9≤1.70; the refractive index of the tenth lens 33 is N10, 1.45≤n10≤1.65; and the refractive index of the eleventh lens 41 is N11, 0.55≤n11≤1.75.

[0033] The first lens, 11, is the "incident window" at the very front of the lens. Its diameter directly determines the "front-end size" and overall volume of the lens. The core design principle of D1 < 26mm revolves around "miniaturization, lightweighting, and structural optimization." The image plane diameter (IC) is the maximum diameter of the lens's "effective imaging range," that is, the diameter of the circular area where the lens can clearly image. The core design principle of IC ≤ 29.5mm is "adapting to mainstream sensor sizes, ensuring uncropped images and meeting edge image quality standards." Together, these two aspects enable the lens to possess practical value in addition to its core performance of "large aperture (F1.6-F2.0) + low distortion (<3%) + stable field of view," as well as "portability, strong adaptability, and mass production feasibility," precisely positioning it in the 100mm prime lens market that caters to both professional and everyday use.

[0034] In one embodiment, an aperture stop 5STOP is provided between the fifth lens 15 and the sixth lens 21 to adjust the light flux according to the actual situation and improve the imaging quality. A photosensitive chip 6 is provided on the image side of the eleventh lens 41, and a filter 7 is provided between the eleventh lens 41 and the photosensitive chip 6. The filter 7 can provide effective protection for the photosensitive chip 6 and can filter out stray light to further improve the imaging quality.

[0035] Specific parameters for one embodiment of the present invention are as follows: The fixed-focus lens 100 in this embodiment has a focal length of f = 43mm, an aperture of F = 1.85, an image plane diameter of 29.5mm, and a diagonal field of view of 37°.

[0036]

[0037] The table below shows the positions of the third lens group 3 in the fixed-focus lens 100 under different focusing states in this embodiment:

[0038] The table below shows one design value for the aspherical coefficient in the fixed-focus lens 100 of this embodiment: The surface profile of an aspherical lens satisfies the formula:

[0039] Where z represents the axial sagitta in the Z direction of the aspherical surface; y represents the height of the aspherical surface; c represents the curvature of the fitted sphere, which is numerically the reciprocal of the radius of curvature; k represents the conic coefficient; and the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms represent higher-order aspherical coefficients, respectively.

[0040]

[0041] in, Figures 2 to 4 This is a simulation diagram of this embodiment.

[0042] The present invention also proposes a camera, which includes a fixed-focus lens 100. The specific structure of the fixed-focus lens 100 is as described in the above embodiments. Since the camera adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here. The camera includes a fixed-focus lens 100, which has an object side and an image side arranged opposite each other along the optical axis. The fixed-focus lens 100 includes a first lens group 1, a second lens group 2, a third lens group 3, and a fourth lens group 4 arranged sequentially from the object side to the image side. The first lens group 1, the third lens group 3, the fifth lens group 15, and the seventh lens group 22 have positive optical power, while the second lens group 2, the fourth lens group 4, and the sixth lens group 21 have negative optical power. The third lens group 3 is movable along the extension direction of the optical axis for focusing, so that the aperture number of the fixed-focus lens 100 is adjustable within the range of greater than or equal to 1.6 and less than or equal to 2.0, the change range of the field of view is less than or equal to 5% of the initial field of view, and the distortion degree of the fixed-focus lens 100 is less than 3%.

[0043] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A fixed-focus lens, characterized in that, The fixed-focus lens has an object side and an image side arranged opposite each other along the optical axis. The fixed-focus lens includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side. In the direction from the object side to the image side, the first lens group sequentially includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens; the second lens group sequentially includes a sixth lens and a seventh lens; the third lens group sequentially includes an eighth lens, a ninth lens, and a tenth lens; and the fourth lens group includes an eleventh lens. The first lens, the fourth lens, the seventh lens, the eighth lens, and the tenth lens have positive optical power; the second lens, the third lens, the fifth lens, the sixth lens, the ninth lens, and the eleventh lens have negative optical power. The third lens group is movably arranged along the extension direction of the optical axis for focusing, so that the aperture number of the fixed-focus lens is adjustable within the range of greater than or equal to 1.6 and less than or equal to 2.0, the range of the change in the field of view is less than or equal to 5% of the initial field of view, and the distortion degree of the fixed-focus lens is less than 3%.

2. The fixed-focus lens as described in claim 1, characterized in that, The total optical length of the fixed-focus lens is TTL, where TTL ≤ 65mm.

3. The fixed-focus lens as described in claim 2, characterized in that, The focal length of the fixed-focus lens is F, where F = 43mm; The focal length of the first lens is f1, where 35mm ≤ f1 ≤ 50mm; The focal length of the second lens is f2, -55mm≤f2≤-40mm; The focal length of the third lens is f3, -55mm≤f3≤-40mm; The focal length of the fourth lens is f4, where 25mm ≤ f4 ≤ 40mm; The focal length of the fifth lens is f5, -90mm≤f5≤-70mm; The focal length of the sixth lens is f6, -80mm≤f6≤-60mm; The focal length of the seventh lens is f7, -80mm≤f7≤-60mm; The focal length of the eighth lens is f8, where 20mm ≤ f8 ≤ 35mm; The focal length of the ninth lens is f9, -40mm≤f9≤-25mm; The focal length of the tenth lens is f10, 210mm≤f10≤280mm; The focal length of the eleventh lens is f11, -50mm≤f11≤-35mm.

4. The fixed-focus lens as described in claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the seventh lens, the eighth lens, the ninth lens, and the eleventh lens are all configured as spherical lenses; Both the sixth lens and the tenth lens are configured as aspherical lenses.

5. The fixed-focus lens as described in claim 3, characterized in that, The first lens is cemented together with the second lens, the fourth lens is cemented together with the fifth lens, and the eighth lens is cemented together with the ninth lens.

6. The fixed-focus lens as described in claim 3, characterized in that, The Abbe number of the first lens is V1, where 45.0 ≤ v1 ≤ 70.0; The Abbe number of the second lens is V2, where 25.0 ≤ v2 ≤ 45.0; The Abbe number of the third lens is V3, where 40.0 ≤ v3 ≤ 65.0; The Abbe number of the fourth lens is V4, where 55.0 ≤ v4 ≤ 95.0; The Abbe number of the fifth lens is V5, where 30.0 ≤ v5 ≤ 45.0; The Abbe number of the sixth lens is V6, where 35.0 ≤ v6 ≤ 50.0; The Abbe number of the seventh lens is V7, where 40.0 ≤ v7 ≤ 65.0; The Abbe number of the eighth lens is V8, where 50.0 ≤ v8 ≤ 95.0; The Abbe number of the ninth lens is V9, where 25.0 ≤ v9 ≤ 45.0; The Abbe number of the tenth lens is V10, where 45.0 ≤ v10 ≤ 95.0; The Abbe number of the eleventh lens is V11, where 30.0 ≤ v11 ≤ 55.

0.

7. The fixed-focus lens as described in claim 3, characterized in that, The refractive index of the first lens is N1, where 1.60 ≤ n1 ≤ 1.75; The refractive index of the second lens is N2, 1.60≤n2≤1.80; The refractive index of the third lens is N3, where 1.50 ≤ n3 ≤ 1.70; The refractive index of the fourth lens is N4, where 1.50 ≤ n4 ≤ 1.70; The refractive index of the fifth lens is N5, where 1.60 ≤ n5 ≤ 1.80; The refractive index of the sixth lens is N6, where 1.70 ≤ n6 ≤ 1.95; The refractive index of the seventh lens is N7, where 1.60 ≤ n7 ≤ 1.75; The refractive index of the eighth lens is N8, where 1.65 ≤ n8 ≤ 1.80; The refractive index of the ninth lens is N9, where 1.55 ≤ n9 ≤ 1.70; The refractive index of the tenth lens is N10, where 1.45 ≤ n10 ≤ 1.65; The refractive index of the eleventh lens is N11, where 1.55 ≤ n11 ≤ 1.

75.

8. The fixed-focus lens as described in claim 1, characterized in that, The diameter D1 of the first lens satisfies: D1 < 26 mm; The image plane diameter IC of the fixed-focus lens satisfies: IC≤29.5mm.

9. The fixed-focus lens as described in claim 8, characterized in that, The fixed-focus lens also includes: An aperture stop, wherein the aperture stop is disposed between the first lens group and the second lens group; and, The photosensitive chip is located on the image side of the fourth lens group; A filter is disposed between the photosensitive chip and the fourth lens.

10. A camera, characterized in that, Including the fixed-focus lens as described in any one of claims 1 to 9.

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