Prime lens

Abstract

The utility model discloses a prime lens. The prime lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens from an object side to an image side along an optical axis, the first lens has negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the second lens has positive focal power, the object side surface of the second lens is a concave surface, and the image side surface is a convex surface; the third lens has positive focal power, the object side surface of the third lens is a concave surface, and the image side surface is a convex surface; the fourth lens has negative focal power; the fifth lens has positive focal power; the sixth lens has negative focal power, the object side surface of the sixth lens is a concave surface, and the image side surface is a convex surface; the seventh lens has positive focal power; the eighth lens has negative focal power.

Description

Technical Field

[0001] The present application relates to the field of optical elements, and in particular to a fixed-focus lens. Background Art

[0002] As society pays more and more attention to public safety and people's safety awareness increases, the market's requirements for the monitoring environment and images of security monitoring facilities are also constantly increasing. As the main component of security monitoring facilities, the performance of fixed-focus lenses determines the imaging quality of security monitoring facilities. However, there are some shortcomings in existing fixed-focus lenses, which limit the use of security monitoring facilities. For example: the lens configuration of existing fixed-focus lenses is difficult to produce a strong correction effect on system aberrations, resulting in poor imaging quality of fixed-focus lenses and difficulty in obtaining high resolution; the optical total length of existing fixed-focus lenses is large, resulting in the overall size and quality of fixed-focus lenses being too high, which is not conducive to the miniaturization of fixed-focus lenses and has high production costs; limited by the aperture number of existing fixed-focus lenses, fixed-focus lenses are difficult to image clearly under low light conditions. Therefore, designing a fixed-focus lens with at least one of the characteristics of high resolution, large aperture, and small size has become a market development trend. Utility Model Content

[0003] The present application provides a fixed-focus lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens in order from the object side to the image side along the optical axis; the first lens has negative optical power, and its object side surface is convex, and its image side surface is concave; the second lens has positive optical power, and its object side surface is concave, and its image side surface is convex; the third lens has positive optical power, and its object side surface is concave, and its image side surface is convex; the fourth lens has negative optical power; the fifth lens has positive optical power; the sixth lens has negative optical power, and its object side surface is concave, and its image side surface is convex; the seventh lens has positive optical power; and the eighth lens has negative optical power.

[0004] According to an exemplary embodiment of the present application, the effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy: -2.21≤F1 / F≤-2.14.

[0005] According to an exemplary embodiment of the present application, the effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy: 1.48≤F2 / F≤1.73.

[0006] According to an exemplary embodiment of the present application, the effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy: 1.15≤F3 / F≤8.31.

[0007] According to an exemplary embodiment of the present application, the effective focal length F4 of the fourth lens and the total effective focal length F of the fixed-focus lens satisfy: -2.7≤F4 / F≤-0.5.

[0008] According to an exemplary embodiment of the present application, the effective focal length F7 of the seventh lens, the effective focal length F8 of the eighth lens and the total effective focal length F of the fixed focus lens satisfy: -1.1≤(F7+F8) / F≤-0.52.

[0009] According to an exemplary embodiment of the present application, the fifth lens and the sixth lens are cemented together to form a cemented lens.

[0010] According to an exemplary embodiment of the present application, the effective focal length F5 of the fifth lens, the effective focal length F6 of the sixth lens and the total effective focal length F of the fixed focus lens satisfy: -1.03≤(F5+F6) / F≤-0.84.

[0011] According to an exemplary embodiment of the present application, the curvature radius R21 of the object side surface of the second lens, the curvature radius R22 of the image side surface of the second lens, and the total effective focal length F of the fixed-focus lens satisfy: -0.43≤F / (R21+R22)≤-0.25.

[0012] According to an exemplary embodiment of the present application, the radius of curvature R31 of the object side surface of the third lens, the radius of curvature R32 of the image side surface of the third lens, and the total effective focal length F of the fixed-focus lens satisfy: -0.57≤F / (R31+R32)≤-0.03.

[0013] According to an exemplary embodiment of the present application, the Abbe number V5 of the fifth lens, the Abbe number V6 of the sixth lens, and the total effective focal length F of the fixed-focus lens satisfy: 4.32≤(V5-V6) / F≤4.65.

[0014] According to an exemplary embodiment of the present application, the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens satisfy: -4.6≤(F2+F3) / F1≤-1.0.

[0015] According to an exemplary embodiment of the present application, the total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy: 2.63≤TTL / F≤2.84.

[0016] According to an exemplary embodiment of the present application, the total optical length TTL of the fixed-focus lens and the total image height H of the fixed-focus lens satisfy: 2.50≤TTL / H≤2.56.

[0017] According to an exemplary embodiment of the present application, the optical back focal length BFL of the fixed-focus lens and the optical total length TTL of the fixed-focus lens satisfy: 0.19≤BFL / TTL≤0.20.

[0018] According to an exemplary embodiment of the present application, the total effective focal length F of the fixed-focus lens and the full image height H of the fixed-focus lens satisfy: 0.90≤F / H≤0.97.

[0019] According to an exemplary embodiment of the present application, the fixed-focus lens satisfies: -1.28≤(F1+F4+F8) / (F2+F3+F7)≤-0.6, wherein F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F7 is the effective focal length of the seventh lens, and F8 is the effective focal length of the eighth lens.

[0020] According to an exemplary embodiment of the present application, the object-side surface of the fourth lens is convex, and the image-side surface is concave; the object-side surface of the fifth lens is convex, and the image-side surface is convex; the object-side surface of the seventh lens is concave, and the image-side surface is convex; the object-side surface of the eighth lens is convex, and the image-side surface is concave.

[0021] The fixed-focus lens provided in the present application uses eight lenses. By designing the optical focal length of the lens and the shapes of the image side and the object side, the fixed-focus lens has at least one of the characteristics of high resolution, large aperture, and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings, in which:

[0023] Figure 1 A schematic structural diagram of a fixed-focus lens according to Embodiment 1 of the present application is shown;

[0024] Figure 2 shows a distortion curve of a fixed-focus lens according to Example 1 of the present application;

[0025] Figure 3 A schematic structural diagram of a fixed-focus lens according to Embodiment 2 of the present application is shown;

[0026] Figure 4 shows a distortion curve of a fixed-focus lens according to Example 2 of the present application;

[0027] Figure 5 A schematic structural diagram of a fixed-focus lens according to Embodiment 3 of the present application is shown;

[0028] Figure 6 shows a distortion curve of a fixed-focus lens according to Example 3 of the present application;

[0029] Figure 7 A schematic structural diagram of a fixed-focus lens according to Embodiment 4 of the present application is shown;

[0030] Figure 8 The distortion curve of the fixed-focus lens according to Example 4 of the present application is shown. DETAILED DESCRIPTION

[0031] In order to better understand the present application, various aspects of the present application are described in detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and do not limit the scope of the present application in any way.

[0032] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0033] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the image plane is called the image side of the lens.

[0034] It should also be understood that the terms "include", "comprising", "having", "including" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. It should be noted that in this specification, the expressions first, second, third, etc. are only used to distinguish one feature from another, and do not represent any limitation on the features.

[0035] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs. Terms should be interpreted as having the same meaning as they have in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] On the one hand, the present application provides a fixed-focus lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens in sequence from the object side to the image side along the optical axis.

[0038] In an exemplary embodiment, the first lens has negative optical power, its object side surface is convex, and its image side surface is concave; the first lens converges the incident light from the object side into the fixed-focus lens, which can expand the incident angle range of the incident light entering the fixed-focus lens, thereby expanding the field of view of the fixed-focus lens and increasing its field of view.

[0039] In an exemplary embodiment, the second lens has positive optical power, its object side surface is concave, and its image side surface is convex; the second lens adjusts the transmission direction of light in the fixed-focus lens, which is beneficial to reducing aberrations, thereby improving the imaging quality of the fixed-focus lens.

[0040] In an exemplary embodiment, the third lens has positive optical power, its object side surface is concave, and its image side surface is convex; the third lens improves the smoothness of light transmission, which is beneficial to reduce the probability of spherical aberration, balance the field curvature of the fixed-focus lens, and thus improve the imaging quality of the fixed-focus lens.

[0041] In an exemplary embodiment, the fourth lens has negative optical power, its object side surface is convex, and its image side surface is concave; the fourth lens adjusts the transmission direction of the line to converge the light in the fixed-focus lens, and corrects chromatic aberration at the same time, which is beneficial to improving the imaging quality of the fixed-focus lens.

[0042] In an exemplary embodiment, the fifth lens has positive optical power, its object side surface is convex, and its image side surface is convex; the sixth lens has negative optical power, its object side surface is concave, and its image side surface is convex; the fifth lens cooperates with the sixth lens to adjust the transmission direction of light and converge the light in the fixed-focus lens.

[0043] In an exemplary embodiment, the seventh lens has positive power, its object side surface is concave, and its image side surface is convex; the eighth lens has negative power, its object side surface is convex, and its image side surface is concave. The seventh lens cooperates with the eighth lens to not only improve the smoothness of light transmission, thereby reducing the probability of various aberrations and reducing the tolerance sensitivity of the fixed-focus lens, thereby improving the assembly yield of the fixed-focus lens; it can also compress the light beam, thereby reducing the divergence angle of the main light, so as to adapt to the CRA (main light angle) curve requirements of the photosensitive chip located on the image plane, and improve the matching degree with the photosensitive chip.

[0044] In an exemplary embodiment, the fixed-focus lens may further include an aperture, which may be disposed between the second lens and the third lens to effectively converge the amount of light entering the fixed-focus lens, reduce the maximum aperture of the lens group before and after the aperture, and shorten the total optical length TTL of the fixed-focus lens. It should be noted that the position of the aperture disclosed herein is only an example and not a limitation. In alternative embodiments, the aperture may also be disposed at other positions according to actual needs. In the present application, the total optical length TTL of the fixed-focus lens refers to the distance from the object side of the first lens to the image plane in the direction of the optical axis.

[0045] In an exemplary embodiment, the effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy: -2.21≤F1 / F≤-2.14. By properly configuring the effective focal length value of the first lens, the incident angle range of the incident light entering the fixed-focus lens can be further expanded, which is conducive to effectively expanding the field of view of the fixed-focus lens.

[0046] In an exemplary embodiment, the effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy: 1.48≤F2 / F≤1.73. By properly configuring the effective focal length value of the second lens, the field curvature of the fixed-focus lens can be further corrected, which is conducive to achieving 4K high resolution, improving the uniformity of the resolution of the fixed-focus lens, and thus improving the resolution of the fixed-focus lens.

[0047] In an exemplary embodiment, the effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy: 1.15≤F3 / F≤8.31. By properly configuring the effective focal length value of the third lens, the field curvature of the fixed-focus lens can be further corrected, which is conducive to achieving 4K high resolution, improving the uniformity of the resolution of the fixed-focus lens, and thus improving the resolution of the fixed-focus lens.

[0048] In an exemplary embodiment, the effective focal length F4 of the fourth lens and the total effective focal length F of the fixed-focus lens satisfy: -2.7≤F4 / F≤-0.5. By controlling the ratio of the effective focal length value of the fourth lens to the total effective focal length of the fixed-focus lens, the smoothness of light transmission can be improved, which is beneficial for correcting chromatic aberration and various aberrations, which is beneficial for increasing the target surface size, thereby increasing the light sensitivity of the image sensor, and further improving the imaging quality of the fixed-focus lens, so that the fixed-focus lens has a higher resolution.

[0049] In an exemplary embodiment, the effective focal length F7 of the seventh lens, the effective focal length F8 of the eighth lens and the total effective focal length F of the fixed-focus lens satisfy: -1.1≤(F7+F8) / F≤-0.52. By properly configuring the focal lengths of the seventh lens and the eighth lens, the field curvature of the fixed-focus lens can be further corrected, which is conducive to achieving 4K high resolution, improving the uniformity of the resolution of the fixed-focus lens, and thus improving the resolution of the fixed-focus lens.

[0050] In an exemplary embodiment, the fifth lens and the sixth lens are cemented together to form a cemented lens. By cementing the fifth lens and the sixth lens together to form a cemented lens, the total optical length of the fixed-focus lens can be shortened, making the structure of the fixed-focus lens more compact.

[0051] In an exemplary embodiment, the effective focal length F5 of the fifth lens, the effective focal length F6 of the sixth lens and the total effective focal length F of the fixed-focus lens satisfy: -1.03≤(F5+F6) / F≤-0.84. By rationally configuring the focal lengths of the fifth lens and the sixth lens, it is not only beneficial to balance various aberrations generated by light passing through the aperture, thereby improving the imaging quality of the fixed-focus lens; it is also beneficial to increase the aperture, so that the aperture number FNO≤1.10. The ultra-large aperture can ensure clear imaging even under low light conditions, which is beneficial to meet the all-weather monitoring requirements of monitoring equipment.

[0052] In an exemplary embodiment, the radius of curvature R21 of the object side surface of the second lens, the radius of curvature R22 of the image side surface of the second lens and the total effective focal length F of the fixed-focus lens satisfy: -0.43≤F / (R21+R22)≤-0.25. By rationally configuring the radius of curvature of the object side surface and the image side surface of the second lens, it is not only beneficial to converge light from different fields of view, thereby improving the light transmission capacity of the fixed-focus lens, thereby improving the image plane brightness of the fixed-focus lens, and improving the resolution of the fixed-focus lens; it is also beneficial to reduce the probability of aberration and balance spherical aberration, thereby improving the imaging quality of the fixed-focus lens.

[0053] In an exemplary embodiment, the radius of curvature R31 of the object side surface of the third lens, the radius of curvature R32 of the image side surface of the third lens and the total effective focal length F of the fixed-focus lens satisfy: -0.57≤F / (R31+R32)≤-0.03. By rationally configuring the radius of curvature of the object side surface and the image side surface of the third lens, the receiving effect of the third lens on the light beam from the second lens can be improved, the spherical aberration introduced by the first lens and the second lens can be compensated, the aberration generated by the first lens and the second lens can be further corrected, and the imaging quality of the fixed-focus lens can be improved.

[0054] In an exemplary embodiment, the Abbe number V5 of the fifth lens, the Abbe number V6 of the sixth lens and the total effective focal length F of the fixed-focus lens satisfy: 4.32≤(V5-V6) / F≤4.65. By controlling the ratio of the difference in the Abbe numbers of the fifth lens and the sixth lens to the total effective focal length of the fixed-focus lens, it is beneficial to balance chromatic aberration and improve the imaging quality of the fixed-focus lens.

[0055] In an exemplary embodiment, the effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens satisfy: -4.6≤(F2+F3) / F1≤-1.0. By rationally configuring the effective focal lengths of the first lens, the second lens, and the third lens, the smoothness of light transmission can be effectively improved, and the aperture of light in the fixed-focus lens can be reduced, so that the fixed-focus lens has a smaller size in the direction perpendicular to the optical axis, which is conducive to achieving lightweight and vertical miniaturization of the fixed-focus lens.

[0056] In an exemplary embodiment, the total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy: 2.63≤TTL / F≤2.84. By controlling the ratio range of the total optical length of the fixed-focus lens to the total effective focal length, the fixed-focus lens has a smaller total optical length when the total effective focal length is constant, and the total optical length TTL of the fixed-focus lens is ≤22.5 mm, which is conducive to achieving lightweight and lateral miniaturization of the fixed-focus lens.

[0057] In an exemplary embodiment, the total optical length TTL of the fixed-focus lens and the full image height H of the fixed-focus lens satisfy: 2.50≤TTL / H≤2.56. By controlling the ratio range of the total optical length of the fixed-focus lens to the full image height, the fixed-focus lens has a smaller total optical length when the full image height is constant, which is conducive to achieving lightweight and lateral miniaturization of the fixed-focus lens.

[0058] In an exemplary embodiment, the optical back focal length BFL of the fixed-focus lens and the optical total length TTL of the fixed-focus lens satisfy: 0.19≤BFL / TTL≤0.20. The optical back focal length BFL is the distance from the center of the image side surface of the eighth lens to the center of the image plane. By controlling the ratio range of the optical back focal length of the fixed-focus lens to the optical total length, it is ensured that the fixed-focus lens can have a small optical total length and a relatively long optical back focal length at the same time, and interference between lenses during the assembly process is prevented, which facilitates the assembly of the fixed-focus lens.

[0059] In an exemplary embodiment, the total effective focal length F of the fixed-focus lens and the full image height H of the fixed-focus lens satisfy: 0.90≤F / H≤0.97. By controlling the ratio range of the total effective focal length of the fixed-focus lens to the full image height, it is beneficial to reduce the distortion of the fixed-focus lens, and the absolute value of the F-Tan (theta) distortion DIS is controlled within 20.62%.

[0060] In an exemplary embodiment, the first to eighth lenses include at least one plastic lens and at least one glass lens. The use of a mixed assembly of glass lenses and plastic lenses is not only conducive to balancing the imaging performance of the fixed-focus lens at different temperatures, so that the fixed-focus lens is not out of focus in a wide temperature range of -40°C to +80°C, and the fixed-focus lens still maintains a high imaging quality under harsh climatic conditions, but also conducive to reducing the cost of the fixed-focus lens; the glass lens is conducive to correcting the chromatic aberration of the fixed-focus lens, improving the color saturation of the fixed-focus lens, and improving the imaging quality of the fixed-focus lens.

[0061] In an exemplary embodiment, the fifth lens and the sixth lens are both glass lenses, the first lens to the fourth lens, and the seventh lens and the eighth lens are all plastic lenses, the fifth lens and the sixth lens are both glass lenses, and the fifth lens and the sixth lens are cemented to form a cemented lens, which can effectively control the trend of light and make the light transition smoothly, thereby helping to reduce the tolerance sensitivity of the fixed-focus lens and improve the lens yield; it is also beneficial to correct the chromatic aberration of the fixed-focus lens and improve the lens quality.

[0062] In an exemplary embodiment, the fixed-focus lens satisfies: -1.28≤(F1+F4+F8) / (F2+F3+F7)≤-0.6, where F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F7 is the effective focal length of the seventh lens, and F8 is the effective focal length of the eighth lens. By reasonably configuring the ratio range of the effective focal length of the plastic lens with positive focal power and the plastic lens with negative focal power, the change in the total effective focal length of the fixed-focus lens at different temperatures is reduced, which is conducive to achieving athermalization of the fixed-focus lens.

[0063] In an exemplary embodiment, the first to fourth lenses, the seventh lens and the eighth lens are all aspherical lenses, and the fifth lens and the sixth lens are all spherical lenses. The characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the center of the lens to the periphery of the lens, an aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. An aspherical lens can eliminate the aberration that occurs during imaging as much as possible, thereby improving the imaging quality.

[0064] The fixed-focus lens provided by the present application can have at least one of the following characteristics at the same time: large aperture (FNO≤1.10), high resolution (4K high resolution), small size (TTL≤22.5mm), high temperature tolerance (no out-of-focus in the temperature range of -40℃~+80℃) and low cost. The large aperture can ensure that the fixed-focus lens can image clearly under low light conditions, and the high temperature tolerance ensures that the fixed-focus lens is not out-of-focus in a wide temperature range, which makes the fixed-focus lens have good imaging quality in poor use environments, which is conducive to meeting the all-weather monitoring requirements of monitoring equipment.

[0065] Those skilled in the art should understand that, without departing from the technical solution claimed in the present application, the number of lenses constituting the fixed-focus lens can be changed to obtain the various results and advantages described in this specification. For example, although eight lenses are described as an example in the embodiment, the optical lens is not limited to including eight lenses. If necessary, the optical lens may also include other numbers of lenses.

[0066] Specific embodiments of the fixed-focus lens applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0067] Example 1

[0068] The following reference Figure 1 A fixed-focus lens according to Embodiment 1 of the present application is described.

[0069] like Figure 1 As shown, the fixed-focus lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 in sequence from the object side to the image side along the optical axis, wherein the fifth lens and the sixth lens are cemented together to form a cemented lens. The first lens L1 has negative power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens L2 has positive power, its object side surface S3 is concave, and its image side surface S4 is convex; the third lens L3 has positive power, its object side surface S5 is concave, and its image side surface S6 is convex; the fourth lens L4 has negative power, its object side surface S7 is convex, and its image side surface S8 is concave; the fifth lens L5 has positive power, its object side surface S9 is convex, and its image side surface S10 is convex; the sixth lens L6 has negative power, its object side surface S10 is concave, and its image side surface S11 is convex; the seventh lens L7 has positive power, its object side surface S12 is concave, and its image side surface S13 is convex; the eighth lens L8 has negative power, its object side surface S14 is convex, and its image side surface S15 is concave. The fifth lens L5 and the sixth lens L6 are both glass lenses, and the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all plastic lenses. The fixed focus lens also includes an aperture STO located between the second lens L2 and the third lens L3, and a protective glass CG located between the eighth lens L8 and the image plane IMAGE, the protective glass CG includes an object side surface S16 and an image side surface S17, and light from the object passes through surfaces S1 to S17 in sequence and is finally imaged on the image plane IMAGE.

[0070] Table 1 shows some basic parameters of each lens in the fixed-focus lens of this embodiment, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0071] Face number Surface type Radius of curvature Thickness / distance Refractive Index Abbe number S1 Aspheric 4.437 1.40 1.54 55.70 S2 Aspheric 2.681 2.90 S3 Aspheric -25.292 2.80 1.54 55.70 S4 Aspheric -5.463 -0.97 STO Spherical endless 1.18 S5 Aspheric -12.010 1.30 1.64 23.50 S6 Aspheric -8.021 0.08 S7 Aspheric 4.531 1.26 1.67 19.40 S8 Aspheric 2.748 0.67 S9 Spherical 6.687 3.77 1.62 63.40 S10 Spherical -6.305 0.70 1.76 26.60 S11 Spherical -17.925 0.73 S12 Aspheric -3.883 1.08 1.54 55.70 S13 Aspheric -2.977 0.08 S14 Aspheric 5.213 1.09 1.54 55.70 S15 Aspheric 3.460 3.41 S16 Spherical endless 0.70 1.52 64.20 S17 Spherical endless 0.30 IMAGE Spherical endless 0.00

[0072] Table 1

[0073] In this embodiment, the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all aspherical lenses, and the surface shape x of the aspherical lens can be defined by but not limited to the following aspherical formula:

[0074]

[0075] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c=1 / R (i.e., the paraxial curvature c is the reciprocal of the curvature radius R in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 2 shows the cone coefficient k and the high-order coefficient A of each aspheric mirror surface S1-S8, S12-S15 that can be used in this embodiment. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 .

[0076] Face number k <![CDATA[A 4 ]]> <![CDATA[A 6 ]]> <![CDATA[A 8 ]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> S1 -0.98 -2.19E-03 -1.43E-04 5.07E-06 1.20E-08 -1.71E-09 0.00E+00 0.00E+00 S2 -0.76 -2.91E-03 -3.27E-04 1.85E-05 -4.62E-07 2.46E-09 0.00E+00 0.00E+00 S3 29.65 9.96E-04 2.01E-05 2.50E-06 -2.45E-07 4.21E-09 0.00E+00 0.00E+00 S4 -0.33 1.85E-03 -1.44E-05 -2.54E-06 1.18E-07 -2.93E-09 0.00E+00 0.00E+00 S5 -30.00 1.50E-03 -6.95E-05 -4.37E-06 8.94E-08 -5.34E-12 0.00E+00 0.00E+00 S6 -26.93 1.57E-03 -1.15E-04 -3.39E-06 2.51E-07 -4.27E-09 0.00E+00 0.00E+00 S7 -4.39 8.86E-04 -5.80E-06 -3.51E-06 1.95E-07 -2.50E-09 0.00E+00 0.00E+00 S8 -3.89 1.55E-03 -8.27E-05 2.52E-06 -8.90E-08 2.87E-09 0.00E+00 0.00E+00 S12 -5.10 -1.02E-03 2.07E-04 -1.34E-05 5.00E-07 -6.97E-09 0.00E+00 0.00E+00 S13 -4.07 3.31E-04 9.79E-05 -2.78E-06 6.95E-08 1.51E-09 0.00E+00 0.00E+00 S14 -14.12 8.57E-04 -3.40E-04 1.73E-05 -6.66E-07 4.21E-09 0.00E+00 0.00E+00 S15 -10.67 -2.44E-03 4.20E-05 -5.74E-06 1.63E-07 -1.63E-09 0.00E+00 0.00E+00

[0077] Table 2

[0078] The fixed-focus lens in this embodiment has a total effective focal length F of 8.01 mm, a total optical length TTL of 22.48 mm, an aperture number FNO of 1.083, and a field of view FOV of 66°.

[0079] Figure 2 The distortion curve of the fixed focus lens of this embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 2 It can be seen that the F-Tan (theta) distortion DIS at the maximum image height is -15.50%, and the fixed-focus lens of this embodiment can achieve good imaging quality.

[0080] Example 2

[0081] The following reference Figure 3 A fixed-focus lens according to Embodiment 2 of the present application is described.

[0082] like Figure 3As shown, the fixed-focus lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 in sequence from the object side to the image side along the optical axis, wherein the fifth lens and the sixth lens are cemented together to form a cemented lens. The first lens L1 has negative power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens L2 has positive power, its object side surface S3 is concave, and its image side surface S4 is convex; the third lens L3 has positive power, its object side surface S5 is concave, and its image side surface S6 is convex; the fourth lens L4 has negative power, its object side surface S7 is convex, and its image side surface S8 is concave; the fifth lens L5 has positive power, its object side surface S9 is convex, and its image side surface S10 is convex; the sixth lens L6 has negative power, its object side surface S10 is concave, and its image side surface S11 is convex; the seventh lens L7 has positive power, its object side surface S12 is concave, and its image side surface S13 is convex; the eighth lens L8 has negative power, its object side surface S14 is convex, and its image side surface S15 is concave. The fifth lens L5 and the sixth lens L6 are both glass lenses, and the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all plastic lenses. The fixed focus lens also includes an aperture STO located between the second lens L2 and the third lens L3, and a protective glass CG located between the eighth lens L8 and the image plane IMAGE, the protective glass CG includes an object side surface S16 and an image side surface S17, and light from the object passes through surfaces S1 to S17 in sequence and is finally imaged on the image plane IMAGE.

[0083] Table 3 shows some basic parameters of each lens in the fixed-focus lens of this embodiment, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0084]

[0085]

[0086] Table 3

[0087] In this embodiment, the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all aspherical lenses. Table 4 shows the cone coefficient k and the high-order coefficient A of each aspherical mirror surface S1-S8, S12-S15 that can be used in this embodiment. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 .

[0088] Face number k <![CDATA[A 4 ]]> <![CDATA[A 6 ]]> <![CDATA[A 8 ]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> S1 -0.98 -2.21E-03 -1.35E-04 4.85E-06 1.47E-08 -1.80E-09 0.00E+00 0.00E+00 S2 -0.76 -2.96E-03 -3.07E-04 1.82E-05 -4.87E-07 3.60E-09 0.00E+00 0.00E+00 S3 29.65 1.08E-03 1.63E-05 2.27E-06 -2.31E-07 3.49E-09 0.00E+00 0.00E+00 S4 -0.33 1.60E-03 -2.31E-05 -2.08E-06 1.11E-07 -3.31E-09 0.00E+00 0.00E+00 S5 -30.00 1.24E-03 -6.20E-05 -4.80E-06 8.37E-08 9.02E-10 0.00E+00 0.00E+00 S6 -26.93 1.59E-03 -1.19E-04 -3.34E-06 2.54E-07 -4.32E-09 0.00E+00 0.00E+00 S7 -4.39 9.03E-04 1.07E-06 -3.56E-06 1.89E-07 -2.55E-09 0.00E+00 0.00E+00 S8 -3.89 1.64E-03 -8.80E-05 2.67E-06 -7.80E-08 2.37E-09 0.00E+00 0.00E+00 S12 -5.10 -1.06E-03 1.96E-04 -1.34E-05 5.06E-07 -6.44E-09 0.00E+00 0.00E+00 S13 -4.07 -4.47E-04 1.10E-04 -3.17E-06 -1.38E-09 3.54E-09 0.00E+00 0.00E+00 S14 -14.12 1.35E-03 -3.54E-04 1.62E-05 -6.33E-07 5.45E-09 0.00E+00 0.00E+00 S15 -10.67 -2.26E-03 2.91E-05 -7.39E-06 2.95E-07 -4.63E-09 0.00E+00 0.00E+00

[0089] Table 4

[0090] The fixed-focus lens in this embodiment has a total effective focal length F of 8.12 mm, a total optical length TTL of 22.45 mm, an aperture number FNO of 1.078, and a field of view FOV of 66°.

[0091] Figure 4 The distortion curve of the fixed focus lens of this embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 4 It can be seen that the F-Tan (theta) distortion DIS at the maximum image height is -16.80%, and the fixed-focus lens of this embodiment can achieve good imaging quality.

[0092] Example 3

[0093] The following reference Figure 5 A fixed-focus lens according to Example 3 of the present application is described.

[0094] like Figure 5 As shown, the fixed-focus lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 in sequence from the object side to the image side along the optical axis, wherein the fifth lens and the sixth lens are cemented together to form a cemented lens. The first lens L1 has negative power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens L2 has positive power, its object side surface S3 is concave, and its image side surface S4 is convex; the third lens L3 has positive power, its object side surface S5 is concave, and its image side surface S6 is convex; the fourth lens L4 has negative power, its object side surface S7 is convex, and its image side surface S8 is concave; the fifth lens L5 has positive power, its object side surface S9 is convex, and its image side surface S10 is convex; the sixth lens L6 has negative power, its object side surface S10 is concave, and its image side surface S11 is convex; the seventh lens L7 has positive power, its object side surface S12 is concave, and its image side surface S13 is convex; the eighth lens L8 has negative power, its object side surface S14 is convex, and its image side surface S15 is concave. The fifth lens L5 and the sixth lens L6 are both glass lenses, and the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all plastic lenses. The fixed focus lens also includes an aperture STO located between the second lens L2 and the third lens L3, and a protective glass CG located between the eighth lens L8 and the image plane IMAGE, the protective glass CG includes an object side surface S16 and an image side surface S17, and light from the object passes through surfaces S1 to S17 in sequence and is finally imaged on the image plane IMAGE.

[0095] Table 5 shows some basic parameters of each lens in the fixed-focus lens of this embodiment, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0096] Face number Surface type Radius of curvature Thickness / distance Refractive Index Abbe number S1 Aspheric 4.436 1.40 1.54 55.70 S2 Aspheric 2.724 2.61 S3 Aspheric -25.793 2.53 1.54 55.70 S4 Aspheric -6.112 -1.50 STO Spherical endless 1.55 S5 Aspheric -266.411 1.44 1.64 23.50 S6 Aspheric -6.156 0.08 S7 Aspheric 5.958 1.13 1.67 19.40 S8 Aspheric 2.386 1.35 S9 Spherical 7.548 3.51 1.62 63.40 S10 Spherical -8.102 0.70 1.76 26.60 S11 Spherical -29.371 0.69 S12 Aspheric -5.597 1.23 1.54 55.70 S13 Aspheric -2.837 0.08 S14 Aspheric 6.944 1.27 1.54 55.70 S15 Aspheric 3.416 3.41 S16 Spherical endless 0.70 1.52 64.20 S17 Spherical endless 0.30 IMAGE Spherical endless 0.00

[0097] Table 5

[0098] In this embodiment, the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all aspherical lenses. Table 6 shows the cone coefficient k and the high-order coefficient A of each aspherical mirror surface S1-S8, S12-S15 that can be used in this embodiment. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 .

[0099]

[0100]

[0101] Table 6

[0102] The fixed-focus lens in this embodiment has a total effective focal length F of 8.41 mm, a total optical length TTL of 22.48 mm, an aperture number FNO of 1.073, and a field of view FOV of 67°.

[0103] Figure 6 The distortion curve of the fixed focus lens of this embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 6 It can be seen that the F-Tan (theta) distortion DIS at the maximum image height is -20.62%, and the fixed-focus lens of this embodiment can achieve good imaging quality.

[0104] Example 4

[0105] The following reference Figure 7 A fixed-focus lens according to Example 4 of the present application is described.

[0106] like Figure 7As shown, the fixed-focus lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 in sequence from the object side to the image side along the optical axis, wherein the fifth lens and the sixth lens are cemented together to form a cemented lens. The first lens L1 has negative power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens L2 has positive power, its object side surface S3 is concave, and its image side surface S4 is convex; the third lens L3 has positive power, its object side surface S5 is concave, and its image side surface S6 is convex; the fourth lens L4 has negative power, its object side surface S7 is convex, and its image side surface S8 is concave; the fifth lens L5 has positive power, its object side surface S9 is convex, and its image side surface S10 is convex; the sixth lens L6 has negative power, its object side surface S10 is concave, and its image side surface S11 is convex; the seventh lens L7 has positive power, its object side surface S12 is concave, and its image side surface S13 is convex; the eighth lens L8 has negative power, its object side surface S14 is convex, and its image side surface S15 is concave. The fifth lens L5 and the sixth lens L6 are both glass lenses, and the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all plastic lenses. The fixed focus lens also includes an aperture STO located between the second lens L2 and the third lens L3, and a protective glass CG located between the eighth lens L8 and the image plane IMAGE, the protective glass CG includes an object side surface S16 and an image side surface S17, and light from the object passes through surfaces S1 to S17 in sequence and is finally imaged on the image plane IMAGE.

[0107] Table 7 shows some basic parameters of each lens in the fixed-focus lens of this embodiment, wherein the units of the radius of curvature and thickness / distance are all millimeters (mm).

[0108] Face number Surface type Radius of curvature Thickness / distance Refractive Index Abbe number S1 Aspheric 4.539 1.40 1.54 55.70 S2 Aspheric 2.721 2.81 S3 Aspheric -24.647 2.87 1.54 55.70 S4 Aspheric -5.369 -0.90 STO Spherical endless 1.18 S5 Aspheric -8.696 1.27 1.64 23.50 S6 Aspheric -7.637 0.08 S7 Aspheric 3.909 1.17 1.67 19.40 S8 Aspheric 2.663 0.43 S9 Spherical 7.163 4.21 1.62 63.40 S10 Spherical -5.661 0.70 1.76 26.60 S11 Spherical -13.744 0.69 S12 Aspheric -3.520 0.89 1.54 55.70 S13 Aspheric -3.007 0.08 S14 Aspheric 5.266 1.18 1.54 55.70 S15 Aspheric 3.711 3.41 S16 Spherical endless 0.70 1.52 64.20 S17 Spherical endless 0.30 IMAGE Spherical endless 0.00

[0109] Table 7

[0110] In this embodiment, the first lens L1 to the fourth lens L4, the seventh lens L7 and the eighth lens L8 are all aspherical lenses. Table 8 shows the cone coefficient k and the high-order coefficient A of each aspherical mirror surface S1-S8, S12-S15 that can be used in this embodiment. 4 , A 6 , A 8 , A 10 , A 12 , A 14 , A 16 .

[0111] Face number k <![CDATA[A 4 ]]> <![CDATA[A 6 ]]> <![CDATA[A 8 ]]> <![CDATA[A 10 ]]> <![CDATA[A 12 ]]> <![CDATA[A 14 ]]> <![CDATA[A 16 ]]> S1 -0.98 -2.23E-03 -1.48E-04 5.58E-06 -1.36E-08 -1.27E-09 0.00E+00 0.00E+00 S2 -0.76 -2.95E-03 -3.07E-04 1.70E-05 -3.94E-07 1.15E-10 0.00E+00 0.00E+00 S3 29.65 -3.68E-03 -4.65E-04 2.85E-05 -7.75E-07 1.50E-09 0.00E+00 0.00E+00 S4 -0.33 -4.40E-03 -6.24E-04 3.99E-05 -1.16E-06 2.88E-09 0.00E+00 0.00E+00 S5 -30.00 -5.12E-03 -7.82E-04 5.14E-05 -1.54E-06 4.26E-09 0.00E+00 0.00E+00 S6 -26.93 -5.84E-03 -9.41E-04 6.28E-05 -1.92E-06 5.64E-09 0.00E+00 0.00E+00 S7 -4.39 -6.57E-03 -1.10E-03 7.43E-05 -2.30E-06 7.03E-09 0.00E+00 0.00E+00 S8 -3.89 -7.29E-03 -1.26E-03 8.57E-05 -2.68E-06 8.41E-09 0.00E+00 0.00E+00 S12 -5.10 -8.01E-03 -1.42E-03 9.71E-05 -3.06E-06 9.79E-09 0.00E+00 0.00E+00 S13 -4.07 -8.73E-03 -1.58E-03 1.09E-04 -3.44E-06 1.12E-08 0.00E+00 0.00E+00 S14 -14.12 -9.46E-03 -1.73E-03 1.20E-04 -3.82E-06 1.26E-08 0.00E+00 0.00E+00 S15 -10.67 -1.02E-02 -1.89E-03 1.31E-04 -4.20E-06 1.39E-08 0.00E+00 0.00E+00

[0112] Table 8

[0113] The fixed-focus lens in this embodiment has a total effective focal length F of 7.94 mm, a total optical length TTL of 22.47 mm, an aperture number FNO of 1.088, and a field of view FOV of 66°.

[0114] Figure 8 The distortion curve of the fixed focus lens of this embodiment is shown, which indicates the distortion magnitude values ​​corresponding to different image heights. Figure 8 It can be seen that the F-Tan (theta) distortion DIS at the maximum image height is -14.97%, and the fixed-focus lens of this embodiment can achieve good imaging quality.

[0115] In summary, the conditional expressions in Examples 1 to 4 satisfy the relationship shown in Table 9.

[0116] Conditional formula\Example one two three Four F1 / F -2.180 -2.170 -2.186 -2.178 F3 / F 4.137 1.736 1.157 8.303 F2 / F 1.541 1.571 1.695 1.528 (F7+F8) / F -0.963 -0.614 -0.600 -1.005 F / (R21+R22) -0.260 -0.266 -0.264 -0.264 F / (R31+R32) -0.400 -0.286 -0.032 -0.486 (V5-V6) / F 4.593 4.531 4.375 4.634 (F5+F6) / F -0.888 -0.861 -0.937 -0.904 TTL / F 2.805 2.767 2.672 2.830 BFL / TTL 0.196 0.196 0.196 0.196 (F2+F3) / F1 -2.605 -1.525 -1.305 -4.514 TTL / H 2.551 2.551 2.551 2.551 F / H 0.909 0.922 0.955 0.901 (F1+F4+F8) / (F2+F3+F7) -0.905 -1.120 -1.186 -0.677 F4 / F -1.799 -1.100 -0.801 -2.500

[0117] Table 9

[0118] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of protection involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other.

Claims

1. A fixed-focus lens, characterized in that: Along the optical axis from the object side to the image side, it includes: The first lens has a negative optical power, and its object side surface is convex and its image side surface is concave; The second lens has positive refractive power, its object side surface is concave and its image side surface is convex; The third lens has positive power, its object side surface is concave and its image side surface is convex; a fourth lens having negative optical power; a fifth lens having positive refractive power; a sixth lens having negative optical power, whose object side surface is concave and image side surface is convex; a seventh lens having positive refractive power; The eighth lens has negative optical power.

2. The fixed-focus lens according to claim 1, characterized in that: The effective focal length F1 of the first lens and the total effective focal length F of the fixed-focus lens satisfy: -2.21≤F1 / F≤-2.

14.

3. The fixed-focus lens according to claim 1, characterized in that: The effective focal length F2 of the second lens and the total effective focal length F of the fixed-focus lens satisfy the following: 1.48≤F2 / F≤1.

73.

4. The fixed-focus lens according to claim 1, characterized in that: The effective focal length F3 of the third lens and the total effective focal length F of the fixed-focus lens satisfy the following: 1.15≤F3 / F≤8.

31.

5. The fixed-focus lens according to claim 1, wherein: The effective focal length F4 of the fourth lens and the total effective focal length F of the fixed-focus lens satisfy: -2.7≤F4 / F≤-0.

5.

6. The fixed-focus lens according to claim 1, wherein: The effective focal length F7 of the seventh lens, the effective focal length F8 of the eighth lens and the total effective focal length F of the fixed-focus lens satisfy: -1.1≤(F7+F8) / F≤-0.

52.

7. The fixed-focus lens according to claim 1, wherein: The fifth lens and the sixth lens are cemented together to form a cemented lens.

8. The fixed-focus lens according to claim 1, wherein: The effective focal length F5 of the fifth lens, the effective focal length F6 of the sixth lens and the total effective focal length F of the fixed-focus lens satisfy: -1.03≤(F5+F6) / F≤-0.

84.

9. The fixed-focus lens according to claim 1, wherein: The curvature radius R21 of the object side surface of the second lens, the curvature radius R22 of the image side surface of the second lens and the total effective focal length F of the fixed-focus lens satisfy: -0.43≤F / (R21+R22)≤-0.

25.

10. The fixed-focus lens according to claim 1, wherein: The curvature radius R31 of the object side surface of the third lens, the curvature radius R32 of the image side surface of the third lens and the total effective focal length F of the fixed-focus lens satisfy: -0.57≤F / (R31+R32)≤-0.

03.

11. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The Abbe number V5 of the fifth lens, the Abbe number V6 of the sixth lens and the total effective focal length F of the fixed-focus lens satisfy: 4.32≤(V5-V6) / F≤4.

65.

12. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The effective focal length F1 of the first lens, the effective focal length F2 of the second lens, and the effective focal length F3 of the third lens satisfy: -4.6≤(F2+F3) / F1≤-1.

0.

13. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The total optical length TTL of the fixed-focus lens and the total effective focal length F of the fixed-focus lens satisfy the following conditions: 2.63≤TTL / F≤2.

84.

14. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The total optical length TTL of the fixed-focus lens and the total image height H of the fixed-focus lens satisfy: 2.50≤TTL / H≤2.

56.

15. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The optical back focal length BFL of the fixed-focus lens and the optical total length TTL of the fixed-focus lens satisfy the following: 0.19≤BFL / TTL≤0.

20.

16. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The total effective focal length F of the fixed-focus lens and the total image height H of the fixed-focus lens satisfy: 0.90≤F / H≤0.

97.

17. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The fixed-focus lens satisfies: -1.28≤(F1+F4+F8) / (F2+F3+F7)≤-0.6, wherein F1 is the effective focal length of the first lens, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F7 is the effective focal length of the seventh lens, and F8 is the effective focal length of the eighth lens.

18. The fixed-focus lens according to any one of claims 1 to 10, characterized in that: The object side surface of the fourth lens is convex, and the image side surface is concave; The object side surface of the fifth lens is convex, and the image side surface is convex; The object side surface of the seventh lens is concave, and the image side surface is convex; The object side surface of the eighth lens is convex, and the image side surface is concave.

Images