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, the first lens group, the second lens group and the third lens group are sequentially arranged from the object side to the image side, and the three lens groups comprise eleven lenses. The first lens, the second lens, the third lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens have positive focal power; the fourth lens, the fifth lens, the tenth lens and the eleventh lens have negative focal power; wherein the second 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 less than or equal to 1.45, the change range of a field angle is less than or equal to 5% of an initial field angle, and the distortion degree of the prime lens is less than 3%. By arranging the eleven lenses, permutation and combination of the lenses and design of the lenses, the technical effects of large aperture and stable imaging are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fixed focus lens, in particular to a fixed focus lens and a camera. BACKGROUND

[0002] The existing lens cannot fully consider the characteristics and requirements of dynamic images in the process of video shooting. For example, the "breathing effect" that occurs when adjusting the focus - the phenomenon of slight enlargement or reduction of the viewing angle caused by the change of the focus, will cause unnecessary shaking of the picture, affecting the smoothness and ornamental value of the video, and the existing camera lens generally has large volume and low imaging quality.

[0003] Therefore, it is particularly important to design a camera lens with large aperture and stable imaging. SUMMARY

[0004] The main purpose of the present application is to provide a fixed focus lens and a camera, which aims to provide a fixed focus lens with large aperture and stable imaging.

[0005] To achieve the above purpose, the fixed focus lens has an object side and an image side arranged opposite along the optical axis direction, and comprises a first lens group, a second lens group and a third lens group arranged in sequence from the object side to the image side: in the direction from the object side to the image side, the first lens group is sequentially arranged with a first lens, a second lens, a third lens, a fourth lens; the second lens group is sequentially arranged with a fifth lens, a sixth lens, a seventh lens and an eighth lens; the third lens group is sequentially arranged with a ninth lens, a tenth lens and an eleventh lens; the first lens, the second lens, the third lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens have positive refractive power; the fourth lens, the fifth lens, the tenth lens and the eleventh lens have negative refractive power; wherein the second 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 in the range of less than or equal to 1.45, 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%.

[0006] In an embodiment, the total optical length of the fixed focus lens is TTL, TTL≤65mm.

[0007] In an embodiment, the focal length of the fixed focus lens is F, F=43mm; The focal length of the first lens is f1, 90mm≤f1≤130mm; The focal length of the second lens is f2, 50mm≤f2≤70mm; The focal length of the third lens is f3, 30mm≤f3≤45mm; a focal length of the fourth lens is f4, -25mm≤f4≤-15mm; a focal length of the fifth lens is f5, -20mm≤f5≤-10mm; a focal length of the sixth lens is f6, 15mm≤f6≤26mm; a focal length of the seventh lens is f7, 350mm≤f7≤500mm; a focal length of the eighth lens is f8, 25mm≤f8≤40mm; a focal length of the ninth lens is f9, 15mm≤f9≤25mm; a focal length of the tenth lens is f10, -28mm≤f10≤-18mm; a focal length of the eleventh lens is f11, -60mm≤f11≤-40mm.

[0008] In an embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the ninth lens, and the tenth lens are all arranged as spherical lenses; the seventh lens, the eighth lens, and the eleventh lens are all arranged as aspherical lenses.

[0009] In an embodiment, the third lens and the fourth lens are arranged as a cemented lens, the fifth lens and the sixth lens are arranged as a cemented lens, and the ninth lens and the tenth lens are arranged as a cemented lens.

[0010] In an embodiment, the first lens has an Abbe number V1, 15.0≤v1≤30.0; the second lens has an Abbe number V2, 45.0≤v2≤60.0; the third lens has an Abbe number V3, 60.0≤v3≤95.0; the fourth lens has an Abbe number V4, 15.0≤v4≤30.0; the fifth lens has an Abbe number V5, 25.0≤v5≤45.0; the sixth lens has an Abbe number V6, 20.0≤v6≤35.0; the seventh lens has an Abbe number V7, 30.0≤v7≤45.0; the eighth lens has an Abbe number V8, 60.0≤v8≤95.0; the ninth lens has an Abbe number V9, 18.0≤v9≤35.0; the tenth lens has an Abbe number V10, 20.0≤v10≤35.0; An Abbe number of the eleventh lens is V11, 35.0≤v11≤55.0.

[0011] In an embodiment, a refractive index of the first lens is N1, 1.90≤n1≤2.05; A refractive index of the second lens is N2, 1.55≤n2≤1.75; A refractive index of the third lens is N3, 1.50≤n3≤1.65; A refractive index of the fourth lens is N4, 1.80≤n4≤1.95; A refractive index of the fifth lens is N5, 1.60≤n5≤1.75; A refractive index of the sixth lens is N6, 1.90≤n6≤2.05; A refractive index of the seventh lens is N7, 1.70≤n7≤1.90; A refractive index of the eighth lens is N8, 1.43≤n8≤1.65; A refractive index of the ninth lens is N9, 1.80≤n9≤2.05; A refractive index of the tenth lens is N10, 1.60≤n10≤1.80; A refractive index of the eleventh lens is N11, 1.60≤n11≤1.75.

[0012] In an embodiment, a diameter D1 of the first lens satisfies: D1<36mm; An image surface diameter IC of the fixed focus lens satisfies: 27.5mm≤IC≤29.5mm.

[0013] In an embodiment, the fixed focus lens further comprises: a diaphragm, the diaphragm being disposed between the first lens group and the second lens group; and, a photosensitive chip, the photosensitive chip being located on an image side of the third lens group; a filter, the filter being disposed between the photosensitive chip and the third lens.

[0014] The application further provides a camera, which comprises a fixed-focus lens, the fixed-focus lens has an object side and an image side which are oppositely arranged along the direction of an optical axis, and the fixed-focus lens comprises a first lens group, a second lens group and a third lens group which are sequentially arranged from the object side to the image side; the first lens group is sequentially arranged with a first lens, a second lens, a third lens and a fourth lens from the object side to the image side; the second lens group is sequentially arranged with a fifth lens, a sixth lens, a seventh lens and an eighth lens; the third lens group is sequentially arranged with a ninth lens, a tenth lens and an eleventh lens; the first lens, the second lens, the third lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens have positive refractive powers; the fourth lens, the fifth lens, the tenth lens and the eleventh lens have negative refractive powers; wherein the second 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 can be adjusted in the range of less than or equal to 1.45, the variation 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%.

[0015] The technical scheme of the application achieves the technical effects of having a large aperture and stable imaging by arranging eleven lenses, arranging and combining the lenses and designing the lenses. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical scheme in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description only show some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings shown.

[0017] Figure 1 The structural schematic diagram of an embodiment of the fixed-focus lens provided by the application is shown in the figure. Figure 2 The spherical aberration curve of the fixed-focus lens in the figure is shown in the figure. Figure 1 The sagittal chromatic aberration curve of the fixed-focus lens in the figure is shown in the figure. Figure 3 The field curvature distortion of the fixed-focus lens in the figure is shown in the figure. Figure 1 The MTF curve of the fixed-focus lens at infinity in the figure is shown in the figure. Figure 4 The MTF curve of the fixed-focus lens at 0.5 m in the figure is shown in the figure. Figure 1 Figure 5 Figure 1 Figure 6 Figure 1

[0018] ​​​​​Brief Description of Drawings 100, fixed focus lens; 1, first lens group; 11, first lens; 12, second lens; 13, third lens; 14, fourth lens; 2, second lens group; 21, fifth lens; 22, sixth lens; 23, seventh lens; 24, eighth lens; 3, third lens group; 31, ninth lens; 32, tenth lens; 33, eleventh lens; 4, diaphragm; 5, photosensitive chip; 6, filter.

[0019] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0021] It should be noted that if the embodiments of the present application involve directionality indication (such as up, down, left, right, front, back, etc.), the directionality indication is only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directionality indication also changes accordingly.

[0022] In addition, if the embodiments of the present application involve descriptions of "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B are satisfied at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of those skilled in the art, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0023] The existing lens does not fully consider the characteristics and requirements of dynamic images in the video shooting process. For example, the "breathing effect" that occurs when adjusting the focus - the phenomenon of slight enlargement or reduction of the angle of view due to focus change, which can cause unnecessary shaking of the picture, affecting the smoothness and watchability of the video, and the existing camera lens generally has large volume and low imaging quality. Therefore, it is particularly important to design a large-aperture and stable imaging camera lens.

[0024] The present application provides a fixed focus lens.

[0025] Please refer to Figure 1 In an embodiment of the present application, the fixed focus lens 100 has an object side and an image side arranged opposite along the optical axis direction, the fixed focus lens 100 includes a first lens group 1, a second lens group 2 and a third lens group 3 arranged in sequence 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 arranged with a first lens 11, a second lens 12, a third lens 13 and a fourth lens 14 in sequence; the second lens group 2 is arranged with a fifth lens 21, a sixth lens 22, a seventh lens 23 and an eighth lens 24 in sequence; the third lens group 3 is arranged with a ninth lens 31, a tenth lens 32 and an eleventh lens 33 in sequence; the first lens 11, the second lens 12, the third lens 13, the sixth lens 22, the seventh lens 23, the eighth lens 24 and the ninth lens 31 have positive refractive power; the fourth lens 14, the fifth lens 21, the tenth lens 32 and the eleventh lens 33 have negative refractive power; wherein the second lens group 2 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 in the range of less than or equal to 1.45, 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%.

[0026] In the technical solution of the present application, the first lens group 1 is used for preliminary converging light rays and correcting basic aberration; the second lens group 2 is used as a core focusing component; and the third lens group 3 is used for fine correction of aberration and optimization of imaging quality. The first, second, third, sixth, seventh, eighth and ninth lenses have the function of converging light rays, improving the light transmission capacity of the lens and laying a foundation for a large aperture. The fourth and fifth lenses and the tenth and eleventh lenses have the function of diverging light rays and offsetting the aberration (such as spherical aberration and chromatic aberration) caused by positive refractive power, thereby ensuring clear imaging. Focusing is achieved by moving the second lens group 2 as a whole along the optical axis, rather than moving a single lens. During focusing, the overall optical structure of the lens changes little, the field of view angle changes little (the change is less than or equal to 5%, which is difficult to detect by the human eye), and the “picture shift” (i.e., the “breathing effect”) during focusing is avoided, which is particularly suitable for video shooting and continuous focusing scenes (such as following a moving object). In summary, the aperture number of the fixed-focus lens 100 can be adjusted in the range of less than or equal to 1.45, the change range of the field of view angle is less than or equal to 5% of the initial field of view angle, and the distortion degree of the fixed-focus lens 100 is less than 3%.

[0027] In order to make the fixed-focus lens 100 have the characteristics of small size, lightness and portability, the total optical length of the fixed-focus lens 100 is TTL, and TTL≤65mm.

[0028] In order to make the focal length of the fixed focus lens 100 reach the set parameters, the focal length of each lens needs to be set, the focal length of the fixed focus lens 100 is F, F = 43mm; the focal length of the first lens 11 is f1, 90mm≤f1≤130mm; as the first lens, weak positive power can reduce the curvature of the lens and reduce spherical aberration; long focal length avoids the front end of the lens being too convex, and helps short TTL design. The focal length of the second lens 12 is f2, 50mm≤f2≤70mm; the light rays of the first lens 11 are accepted, and the medium positive power further converges the light rays, and at the same time, the weak + medium positive power gradient is formed with the first lens 11, so as to avoid the aberration caused by too fast convergence of the light rays. The focal length of the third lens 13 is f3, 30mm≤f3≤45mm; the convergence efficiency of the light rays is strengthened, and sufficient light quantity is provided for a large aperture; the focal length is shorter than that of the previous two lenses, and the power is stronger, so as to balance the overall length of the first lens group 1. The focal length of the fourth lens 14 is f4, -25mm≤f4≤-15mm; as the only negative power lens of the first lens group 1, the short focal length corresponds to strong negative power, and the spherical aberration and chromatic aberration accumulated by the previous three positive lenses are effectively offset; at the same time, the light ray bundle is compressed, the space of the rear lens group is saved, and short TTL is helped. The focal length of the fifth lens 21 is f5, -20mm≤f5≤-10mm; as the first lens of the focusing group, strong negative power is used for correcting the residual aberration of the front group, and at the same time, the light rays of the subsequent positive lens are “paved”; the short focal length design makes the lens group more compact, and the focusing along the optical axis is facilitated. The focal length of the sixth lens 22 is f6, 15mm≤f6≤26mm; it is used for strong positive power to quickly converge light rays, make up for the light ray divergence of the fifth lens 21 (negative power), and ensure the light transmission efficiency; the short focal length makes the overall volume of the second lens group 2 small, and the influence on the total length of the lens is small when moving (reducing the change of the field angle). The focal length of the seventh lens 23 is f7, 350mm≤f7≤500mm; as the key “correction lens”: extremely weak positive power almost does not change the direction of the light rays, and is specially used for fine correction of chromatic aberration and coma (core aberration under a large aperture); the super-long focal length means that the lens curvature is extremely small, the machining precision is high, but the correction effect is more accurate. The focal length of the eighth lens 24 is f8, 25mm≤f8≤40mm; the light rays of the seventh lens 23 are accepted, the medium positive power stabilizes the direction of the light ray propagation, and “reduces the burden” of the third lens group 3; the combination of the sixth lens, the seventh lens and the eighth lens forms strong positive + extremely weak positive + medium positive, and further optimizes the aberration. The focal length of the ninth lens 31 is f9, 15mm≤f9≤25mm; the ninth lens 31 is the core convergence lens of the third lens group 3, and the strong positive power focuses the light rays accurately to the imaging surface; the short focal length design makes the third lens group 3 more compact, and compresses the total length of TTL. The focal length of the tenth lens 32 is f10, -28mm≤f10≤-18mm; the spherical aberration and field curvature of the ninth lens 31 are corrected, the angle of the light rays is fine adjusted, and the imaging clarity of the edge field is ensured; the short negative focal length corresponds to strong negative power, and the correction efficiency is high.The focal length of the eleventh lens 33 is f11, and -60mm≤f11≤-40mm. The last piece of lens, the medium negative power, is used for final correction of residual aberration (especially edge chromatic aberration), while "widening" the light beam, adapting the size of the imaging surface; the medium-long focal length avoids excessive divergence of light, ensuring uniformity of central and edge image quality.

[0029] In order to meet the core technical indicators of large aperture, low distortion, and stable field of view, and balance the production practicability and cost, the optimal solution of performance and cost performance is achieved. The first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 21, the sixth lens 22, the ninth lens 31, and the tenth lens 32 are all set as spherical lenses; the seventh lens 23, the eighth lens 24, and the eleventh lens 33 are all set as aspherical lenses. With 8 pieces of mature spherical lens process to build the basic optical architecture, 3 pieces of aspherical lens are used to accurately overcome the core aberration pain points of large aperture and short TTL, and finally realize the perfect balance of full-scene adaptation, professional performance, compactness, and controllable cost. Among them, the aspherical lens optimizes the aberration and illumination of the edge field of view, making the "full-scene adaptation" of 43mm focal length more practical (such as shooting large-scene buildings, the edge building lines are not distorted and blurred). The aspherical design of the eleventh lens 33 reduces the edge dark angle, without the need for excessive brightening in the later stage, improving the shooting efficiency; multiple spherical lenses are arranged in the second lens group 2, and the optical parameter fluctuation is smaller when moving, further ensuring that the field of view angle change is ≤5%, and the video follow-up is more stable.

[0030] In one type of embodiment, the third lens 13 and the fourth lens 14 are glued, the fifth lens 21 and the sixth lens 22 are glued, and the ninth lens 31 and the tenth lens 32 are glued. Three groups of glued lenses respectively form three times of chromatic aberration correction in three lens groups, from the light entering the lens to the focusing imaging, the chromatic aberration is suppressed throughout the process, avoiding the problem of "edge purple and center yellow" under large aperture, and ensuring the purity of the picture color. The core source of distortion is the unevenness of the light propagation angle, and the glued lens can indirectly optimize the refraction angle of the light through the precise matching of the material and the focal length; especially the glued design in the second lens group 2 avoids the distortion fluctuation caused by lens movement during focusing, ensuring that the distortion is ≤3% whether focusing to the close-up or the telephoto end. Three groups of glued lenses reduce 3 air gaps (about 2-3mm space is saved after gluing each two independent lenses), and the cumulative lens length is shortened by about 6-9mm, which is the key to realizing "11 lenses + 43mm focal length + TTL≤65mm".

[0031] In order to accurately correct chromatic aberration, balance "refractive power" and "dispersion control", and ensure the consistency of full-scene imaging, the Abbe number of the first lens 11 is V1, 15.0≤v1≤30.0; the Abbe number of the second lens 12 is V2, 45.0≤v2≤60.0; the Abbe number of the third lens 13 is V3, 60.0≤v3≤95.0; the Abbe number of the fourth lens 14 is V4, 15.0≤v4≤30.0; the Abbe number of the fifth lens 21 is V5, 25.0≤v5≤45.0; the Abbe number of the sixth lens 22 is V6, 20.0≤v6≤35.0; the Abbe number of the seventh lens 23 is V7, 30.0≤v7≤45.0; the Abbe number of the eighth lens 24 is V8, 60.0≤v8≤95.0; the Abbe number of the ninth lens 31 is V9, 18.0≤v9≤35.0; the Abbe number of the tenth lens 32 is V10, 20.0≤v10≤35.0; the Abbe number of the eleventh lens 33 is V11, 35.0≤v11≤55.0.

[0032] In order to ensure that the fixed focus lens 100100 meets the predetermined use requirements in terms of aberration, chromatic aberration, thermal stability, manufacturing feasibility, weight and volume, and field of view range, the refractive index of each lens in the fixed focus lens 100100 needs to be limited: the refractive index of the first lens 11 is N1, 1.90≤n1≤2.05; the refractive index of the second lens 12 is N2, 1.55≤n2≤1.75; the refractive index of the third lens 13 is N3, 1.50≤n3≤1.65; the refractive index of the fourth lens 14 is N4, 1.80≤n4≤1.95; the refractive index of the fifth lens 21 is N5, 1.60≤n5≤1.75; the refractive index of the sixth lens 22 is N6, 1.90≤n6≤2.05; the refractive index of the seventh lens 23 is N7, 1.70≤n7≤1.90; the refractive index of the eighth lens 24 is N8, 1.43≤n8≤1.65; the refractive index of the ninth lens 31 is N9, 1.80≤n9≤2.05; the refractive index of the tenth lens 32 is N10, 1.60≤n10≤1.80; the refractive index of the eleventh lens 33 is N11, 1.60≤n11≤1.75.

[0033] The core requirement of a large aperture is "light throughput", but the light throughput is not only determined by the lens diameter, but also directly related to the lens curvature and power distribution: the first lens 11 can adopt a long focal length (90-130mm) and a weak positive power, which allows the lens to adopt a gentler curvature and achieve sufficient light throughput without excessively large diameter (avoiding forcibly increasing the lens diameter for a large aperture). In combination with the high efficiency convergence of the third lens group 3 (especially the strong positive power of the sixth and ninth lenses), an ultra-large aperture of f≤1.45 is finally achieved under the premise of D1<36mm, solving the industry pain point that a large aperture equals a large diameter. The smaller the diameter of the first lens 11, the thinner the wall thickness of the front end of the lens barrel and the installation space of the light shield, which indirectly helps to shorten the overall TTL; In an embodiment, the image surface diameter IC of the fixed focus lens 100 satisfies: 27.5mm≤IC≤29.5mm. IC=27.5-29.5mm is specifically adapted to a full-frame sensor, so that the user does not need to worry about "image circle insufficient to cause picture cropping", and can fully exert the high resolution and shallow depth of field advantages of the full-frame, meeting the professional needs of commercial photography, portrait creation, video shooting, etc.

[0034] The fixed focus lens 100 further comprises: a diaphragm 4, a photosensitive chip 5 and a filter 6; the diaphragm 4 is arranged between the first lens group 1 and the second lens group 2, and is used to adjust the light flux according to the actual situation and improve the imaging quality; the photosensitive chip 5 is located on the image side of the third lens group 3; the filter 6 is arranged between the photosensitive chip 5 and the third lens 13. The filter 6 can provide effective protection for the photosensitive chip 5, and can also filter out stray light, further improving the imaging quality.

[0035] For the specific parameters of an example embodiment provided by the present application: The focal length f of the fixed focus lens 100 of the present embodiment is 43mm, the aperture value F is 1.45, and the image surface diameter is 29.5mm. The diagonal field of view angle is 37°.

[0036]

[0037] The following table shows the position of the focusing moving group of the fixed focus lens 100 of the present embodiment under different focusing states:

[0038] The following table shows a design value of the aspheric surface coefficients in the fixed focus lens 100 of the present embodiment: The surface shape of the aspheric lens satisfies the formula:

[0039] Wherein, z represents the axial height of the aspheric surface Z direction, y represents the height of the aspheric surface, c represents the curvature of the fitting sphere, the value is the reciprocal of the curvature radius, k represents the conic coefficient, 4th order term, 6th order term, 8th order term, 10th order term, 12th order term, 14th order term, 16th order term represents the high-order aspheric surface coefficient.

[0040]

[0041] Wherein, Figures 2 to 6 The simulation schematic diagram of this embodiment is shown.

[0042] The application also provides a camera, which comprises a fixed focus lens 100, the specific structure of which is referred to the above-mentioned embodiments, since the camera adopts all the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here. Wherein, the fixed focus lens 100 has an object side and an image side which are oppositely arranged along the optical axis direction, the fixed focus lens 100 comprises a first lens group 1, a second lens group 2 and a third lens group 3 which are sequentially arranged from the object side to the image side: the first lens group 1 is sequentially arranged with a first lens 11, a second lens 12, a third lens 13 and a fourth lens 14 in the direction from the object side to the image side; the second lens group 2 is sequentially arranged with a fifth lens 21, a sixth lens 22, a seventh lens 23 and an eighth lens 24; the third lens group 3 is sequentially arranged with a ninth lens 31, a tenth lens 32 and an eleventh lens 33; the first lens 11, the second lens 12, the third lens 13, the sixth lens 22, the seventh lens 23, the eighth lens 24 and the ninth lens 31 have positive refractive power; the fourth lens 14, the fifth lens 21, the tenth lens 32 and the eleventh lens 33 have negative refractive power; wherein, the second lens group 2 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 in the range of less than or equal to 1.45, 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-mentioned is only an exemplary embodiment of the application, and does not limit the patent scope of the application, any equivalent structural transformation made by using the content of the application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the application.

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, and a third 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, and a fourth lens; the second lens group sequentially includes a fifth lens, a sixth lens, a seventh lens, and an eighth lens; and the third lens group sequentially includes a ninth lens, a tenth lens, and an eleventh lens. The first lens, second lens, third lens, sixth lens, seventh lens, eighth lens, and ninth lens have positive optical power; and the fourth lens, fifth lens, tenth lens, and eleventh lens have negative optical power. The second 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 a range of less than or equal to 1.45, 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, 90mm≤f1≤130mm; The focal length of the second lens is f2, 50mm≤f2≤70mm; The focal length of the third lens is f3, where 30mm ≤ f3 ≤ 45mm; The focal length of the fourth lens is f4, -25mm≤f4≤-15mm; The focal length of the fifth lens is f5, -20mm≤f5≤-10mm; The focal length of the sixth lens is f6, 15mm≤f6≤26mm; The focal length of the seventh lens is f7, 350mm≤f7≤500mm; The focal length of the eighth lens is f8, where 25mm ≤ f8 ≤ 40mm; The focal length of the ninth lens is f9, 15mm≤f9≤25mm; The focal length of the tenth lens is f10, -28mm≤f10≤-18mm; The focal length of the eleventh lens is f11, -60mm≤f11≤-40mm.

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 sixth lens, the ninth lens, and the tenth lens are all configured as spherical lenses; The seventh lens, the eighth lens, and the eleventh lens are all configured as aspherical lenses.

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

6. The fixed-focus lens as described in claim 3, characterized in that, The Abbe number of the first lens is V1, where 15.0 ≤ v1 ≤ 30.0; The Abbe number of the second lens is V², where 45.0 ≤ v² ≤ 60.0; The Abbe number of the third lens is V3, where 60.0 ≤ v3 ≤ 95.0; The Abbe number of the fourth lens is V4, where 15.0 ≤ v4 ≤ 30.0; The Abbe number of the fifth lens is V5, where 25.0 ≤ v5 ≤ 45.0; The Abbe number of the sixth lens is V6, where 20.0 ≤ v6 ≤ 35.0; The Abbe number of the seventh lens is V7, where 30.0 ≤ v7 ≤ 45.0; The Abbe number of the eighth lens is V8, where 60.0 ≤ v8 ≤ 95.0; The Abbe number of the ninth lens is V9, where 18.0 ≤ v9 ≤ 35.0; The Abbe number of the tenth lens is V10, where 20.0 ≤ v10 ≤ 35.0; The Abbe number of the eleventh lens is V11, where 35.0 ≤ 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 1.90 ≤ n1 ≤ 2.05; The refractive index of the second lens is N2, where 1.55 ≤ n2 ≤ 1.75; The refractive index of the third lens is N3, where 1.50 ≤ n3 ≤ 1.65; The refractive index of the fourth lens is N4, where 1.80 ≤ n4 ≤ 1.95; The refractive index of the fifth lens is N5, where 1.60 ≤ n5 ≤ 1.75; The refractive index of the sixth lens is N6, where 1.90 ≤ n6 ≤ 2.05; The refractive index of the seventh lens is N7, where 1.70 ≤ n7 ≤ 1.90; The refractive index of the eighth lens is N8, where 1.43 ≤ n8 ≤ 1.65; The refractive index of the ninth lens is N9, where 1.80 ≤ n9 ≤ 2.05; The refractive index of the tenth lens is N10, where 1.60 ≤ n10 ≤ 1.80; The refractive index of the eleventh lens is N11, where 1.60 ≤ 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 < 36 mm; The image plane diameter IC of the fixed-focus lens satisfies: 27.5mm≤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 third lens group; A filter is disposed between the photosensitive chip and the third 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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