A telephoto lens

Abstract

The present invention discloses a telephoto lens, comprising a first lens, an aperture, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, arranged in sequence along an optical axis from the object side to the image side. The first lens has a negative refractive power, the second lens has a positive refractive power, the third lens has a negative refractive power, the fourth lens has a positive refractive power, the fifth lens has a negative refractive power, and the sixth lens has a positive refractive power. The first to sixth lenses are all plastic aspheric lenses. The telephoto lens of the present invention uses six plastic aspheric lenses, has an optical TTL of less than 15mm, is low in cost, and has a small overall lens size. The lens has an FNO of 1.5, high light transmission and brightness, enabling the lens to achieve good imaging quality even in dark environments. The lens has a large field of view, a wide range of captured images, and high image resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a telephoto lens. Background Art

[0002] A telephoto lens, also known as a telephoto lens or telephoto lens, is a photographic lens with a longer focal length than a standard lens. Currently available telephoto lenses, due to their large focal length, have a high TTL (Thin Turns) ratio in the optical system. The excessive number of lens elements also results in a bulky and expensive lens. Furthermore, the lens has a low light transmission rate, resulting in insufficient brightness and poor imaging in dim conditions. Furthermore, conventional telephoto lenses have a narrow field of view, mostly within 30°, limiting their ability to capture a limited frame, which can be a limitation when capturing large scenes.

[0003] In view of this, the inventors of the present application invented a telephoto lens. Summary of the Invention

[0004] The object of the present invention is to provide a telephoto lens with small size, low cost, large light transmission, large field of view and high resolution.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a telephoto lens, comprising a first lens, an aperture, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, arranged in sequence along an optical axis from the object side to the image side, wherein each of the first to sixth lenses includes an object-side surface facing the object side and through which imaging light passes, and an image-side surface facing the image side and through which imaging light passes;

[0006] The first lens has a negative refractive power, and the object-side surface of the first lens is convex, and the image-side surface is concave;

[0007] The second lens has positive refractive power, and the object side surface of the second lens is convex near the optical axis, and the image side surface is convex;

[0008] The third lens has a negative refractive power, and the object-side surface of the third lens is convex, and the image-side surface is concave;

[0009] The fourth lens element has positive refractive power, and the object-side surface and image-side surface of the fourth lens element are convex;

[0010] The fifth lens element has a negative refractive power, and the object-side surface of the fifth lens element is concave, and the image-side surface of the fifth lens element is convex;

[0011] The sixth lens element has positive refractive power, and the object side surface of the sixth lens element is convex near the optical axis, and the image side surface is concave near the optical axis;

[0012] Among them, the first lens to the sixth lens are all plastic aspherical lenses.

[0013] Further, the lens satisfies: -30mm < f1 < -27mm, 6mm < f2 < 8mm, -9mm < f3 < -7.5mm, 5.5mm < f4 < 8mm, -10mm < f5 < -8.5mm, 8mm < f6 < 9.5mm, where f1, f2, f3, f4, f5, and f6 are the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively.

[0014] Further, the lens satisfies: 3 < |f1 / f| < 4, 0.5 < |f2 / f| < 1, 0.5 < |f3 / f| < 1.5, 0.5 < |f4 / f| < 1.5, 1 < |f5 / f| < 2, 0.5 < |f6 / f| < 1.5, where f is the overall focal length of the lens, and f1, f2, f3, f4, f5, and f6 are the focal lengths of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively.

[0015] Further, the lens satisfies: 1.5 < nd1 < 1.6, 49 < vd1 < 60, 1.5 < nd2 < 1.6, 50 < vd2 < 60, 1.6 < nd3 < 1.7, 18 < vd3 < 30, 1.54 < nd4 < 1.7, 50 < vd4 < 70, 1.6 < nd5 < 1.7, 18 < vd5 < 25, 1.5 < nd6 < 1.7, 50 < vd6 < 60, where nd1, nd2, nd3, nd4, nd5, and nd6 are the refractive indices of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively, and vd1, vd2, vd3, vd4, vd5, and vd6 are the dispersion coefficients of the first lens, second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively.

[0016] Further, the lens satisfies: 6mm < CT2 + CT3 + CT4 + CT5 + CT6 < 7mm, where CT2, CT3, CT4, CT5, and CT6 are the central thicknesses of the second lens, third lens, fourth lens, fifth lens, and sixth lens, respectively.

[0017] Further, the lens satisfies: 3.5 ≤ TTL / AAG ≤ 4.5, where TTL is the overall optical length of the lens, and AAG is the sum of the air gaps between adjacent two lenses of the first to sixth lenses on the optical axis.

[0018] Further, the overall optical length TTL of the lens satisfies: TTL < 15mm.

[0019] Furthermore, the lens satisfies: 0.8≤AAG / BFL≤1.5, where AAG is the sum of the air gaps between two adjacent lenses on the optical axis of the first to sixth lenses, and BFL is the distance from the image side surface of the sixth lens to the imaging surface of the lens on the optical axis.

[0020] Furthermore, the lens satisfies: 0.45≤IMH / EFL≤0.6, wherein IMH is the image half height of the lens, and EFL is the effective focal length of the lens.

[0021] Furthermore, the effective focal length EFL of the lens satisfies: 7.45mm <EFL<8.0mm。

[0022] After adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0023] The telephoto lens of the present invention adopts 6 plastic aspherical lenses, has an optical TTL of less than 15mm, is low in cost, and has a small overall size; the lens has an FNO of 1.5, has high light transmission and brightness, and can achieve good imaging quality even in dark environments; the lens has a large field of view and a large angle, and can capture a wide range of images, while also having high image resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a light path diagram of Example 1 of the present invention;

[0025] Figure 2 : This is an MTF curve diagram of the lens under visible light in Example 1 of the present invention;

[0026] Figure 3 : is a defocus curve diagram of the lens under visible light in Example 1 of the present invention;

[0027] Figure 4 2 is a diagram of lateral chromatic aberration of the lens under visible light in Example 1 of the present invention;

[0028] Figure 5 This is a diagram of longitudinal chromatic aberration of the lens under visible light in Example 1 of the present invention;

[0029] Figure 6 Graphs showing field curvature and distortion of the lens under visible light in Example 1 of the present invention;

[0030] Figure 7 This is a light path diagram of Example 2 of the present invention;

[0031] Figure 8 This is an MTF curve diagram of the lens under visible light in Example 2 of the present invention;

[0032] Figure 9 : is a defocus curve diagram of the lens under visible light in Example 2 of the present invention;

[0033] Figure 10 This is a diagram of lateral chromatic aberration of the lens under visible light in Example 2 of the present invention;

[0034] Figure 11 This is a diagram of longitudinal chromatic aberration of the lens under visible light in Example 2 of the present invention;

[0035] Figure 12 Graphs showing field curvature and distortion of the lens under visible light in Example 2 of the present invention;

[0036] Figure 13 This is a light path diagram of Example 3 of the present invention;

[0037] Figure 14 : This is an MTF curve diagram of the lens under visible light in Example 3 of the present invention;

[0038] Figure 15 : is a defocus curve diagram of the lens under visible light in Example 3 of the present invention;

[0039] Figure 16 This is a diagram of lateral chromatic aberration of the lens under visible light in Example 3 of the present invention;

[0040] Figure 17 This is a diagram of longitudinal chromatic aberration of the lens under visible light in Example 3 of the present invention;

[0041] Figure 18 Graphs showing field curvature and distortion of the lens under visible light in Example 3 of the present invention;

[0042] Figure 19 This is a light path diagram of Example 4 of the present invention;

[0043] Figure 20 This is an MTF curve diagram of the lens under visible light in Example 4 of the present invention;

[0044] Figure 21 : is a defocus curve diagram of the lens under visible light in Example 4 of the present invention;

[0045] Figure 22 This is a diagram of lateral chromatic aberration of the lens under visible light in Example 4 of the present invention;

[0046] Figure 23 This is a diagram of longitudinal chromatic aberration of the lens under visible light in Example 4 of the present invention;

[0047] Figure 24 Graphs showing field curvature and distortion of the lens under visible light in Example 4 of the present invention;

[0048] Figure 25 This is a light path diagram of Example 5 of the present invention;

[0049] Figure 26: This is an MTF curve diagram of the lens under visible light in Example 5 of the present invention;

[0050] Figure 27 : is a defocus curve diagram of the lens under visible light in Example 5 of the present invention;

[0051] Figure 28 2 is a diagram of lateral chromatic aberration of the lens under visible light in Example 5 of the present invention;

[0052] Figure 29 This is a diagram of longitudinal chromatic aberration of the lens under visible light in Example 5 of the present invention;

[0053] Figure 30 Graphs showing field curvature and distortion of the lens under visible light in Example 5 of the present invention.

[0054] Description of reference numerals:

[0055] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Aperture diaphragm; 8. Protective glass. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] Here, "a lens having a positive (or negative) refractive power" means that the lens's paraxial refractive power, calculated using Gaussian optics theory, is positive (or negative). The "object-side (or image-side) of a lens" is defined as the specific area of ​​the lens surface through which the imaging light passes. The concavity or convexity of a lens's surface can be determined using the same method commonly used by those skilled in the art: the sign of the radius of curvature (abbreviated as R value). R values ​​are commonly used in optical design software such as Zemax or CodeV. R values ​​are also commonly found in lens data sheets within optical design software. For the object-side surface, a positive R value indicates a convex surface; a negative R value indicates a concave surface. Conversely, for the image-side surface, a positive R value indicates a concave surface; a negative R value indicates a convex surface.

[0058] The present invention discloses a telephoto lens, comprising a first lens 1, an aperture 7, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6, which are arranged in sequence along an optical axis from the object side to the image side. The first lens 1 is a front lens group, and the second lenses 2 to the sixth lenses 6 are a rear lens group.

[0059] Among them, the first lens 1 to the sixth lens 6 each include an object side facing the object and allowing imaging light to pass through, and an image side facing the image and allowing imaging light to pass through;

[0060] The first lens 1 has a negative refractive power, and the object side of the first lens 1 is convex, and the image side is concave;

[0061] The second lens 2 has a positive refractive power, and the object side of the second lens 2 is convex near the optical axis, and the image side is convex;

[0062] The third lens 3 has a negative refractive power, and the object side of the third lens 3 is convex, and the image side is concave;

[0063] The fourth lens 4 has a positive refractive power, and the object side of the fourth lens 4 is convex, and the image side is convex;

[0064] The fifth lens 5 has a negative refractive power, and the object side of the fifth lens 5 is concave, and the image side is convex;

[0065] The sixth lens 6 has a positive refractive power, and the object side of the sixth lens 6 is convex near the optical axis, and the image side is concave near the optical axis.

[0066] The first lens 1 to the sixth lens 6 are all plastic aspherical lenses. The six lenses are all designed with 16th-order even aspheric surfaces, which is beneficial for correcting secondary spectra and higher-order aberrations; and the third lens 3 and the fifth lens 5 are made of high-refractive-index materials, which can better optimize the optical structure and is beneficial for the lens structure design, reducing the lens cost.

[0067] This lens satisfies: -30 < f1 < -27, 6 < f2 < 8, -9 < f3 < -7.5, 5.5 < f4 < 8, -10 < f5 < -8.5, 8 < f6 < 9.5, where f1, f2, f3, f4, f5, f6 are the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively.

[0068] This lens satisfies: 3 < |f1 / f| < 4, 0.5 < |f2 / f| < 1, 0.5 < |f3 / f| < 1.5, 0.5 < |f4 / f| < 1.5, 1 < |f5 / f| < 2, 0.5 < |f6 / f| < 1.5, where f is the overall focal length of this lens, and f1, f2, f3, f4, f5, f6 are the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively.

[0069] The lens satisfies the following conditions: 1.5 < nd1 < 1.6, 49 < vd1 < 60, 1.5 < nd2 < 1.6, 50 < vd2 < 60, 1.6 < nd3 < 1.7, 18 < vd3 < 30, 1.54 < nd4 < 1.7, 50 < vd4 < 70, 1.6 < nd5 < 1.7, 18 < vd5 < 25, 1.5 < nd6 < 1.7, 50 < vd6 < 60, where nd1, nd2, nd3, nd4, nd5, and nd6 are the refractive indices of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively, and vd1, vd2, vd3, vd4, vd5, and vd6 are the Abbe numbers of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively.

[0070] The lens satisfies the following conditions: 6 mm < CT2 + CT3 + CT4 + CT5 + CT6 < 7 mm, where CT2, CT3, CT4, CT5, and CT6 are the central thicknesses of the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 respectively. And the lens satisfies the following condition: 3.5 ≤ TTL / AAG ≤ 4.5, where TTL is the total optical length of the lens, and AAG is the sum of the air gaps between adjacent two lenses of the first to the sixth lenses 6 on the optical axis. Thus, the combined length of the rear lens group (the second lens 2 to the sixth lens 6) can be effectively controlled, which can not only balance the rear lens group's optical power well and improve the imaging quality, but also effectively control the overall length of the lens, which is more conducive to the miniaturization of the lens.

[0071] The lens satisfies the following condition: 0.8 ≤ AAG / BFL ≤ 1.5, where AAG is the sum of the air gaps between adjacent two lenses of the first to the sixth lenses 6 on the optical axis, and BFL is the distance from the image side of the sixth lens 6 to the lens imaging plane on the optical axis. By controlling the ratio of the air gap between each lens and the back focal length (BFL), the optical power between each lens can be better distributed, and at the same time, the system field curvature can be controlled, which can effectively improve the overall imaging quality of the lens.

[0072] The lens satisfies the following condition: 0.45 ≤ IMH / EFL ≤ 0.6, where IMH is the image-side semi-image height of the lens, and EFL is the effective focal length of the lens. By controlling the ratio of the image height to the focal length, the distortion of the system can be made smaller, thereby effectively improving the imaging quality of the lens.

[0073] The effective focal length EFL of the lens satisfies the following condition: 7.45 mm < EFL < 8.0 mm.

[0074] The total optical length TTL of the lens satisfies the following condition: TTL < 15 mm. The small total optical length and small volume of the lens make its installation and use extremely convenient.

[0075] The maximum aperture of this lens is F / N=1.5. This high aperture improves image edge illumination and enhances image brightness.

[0076] This lens has a wide field of view (HFOV = 44° and DFOV > 52°), which increases the overall field of view of a telephoto lens and enhances its practicality. The lens also offers excellent image quality, with a center MTF greater than 0.65 and an edge MTF greater than 0.4 at a spatial frequency of 150 lp / mm.

[0077] The telephoto lens of the present invention will be described in detail below with reference to specific embodiments.

[0078] Example 1

[0079] Reference Figure 1 As shown, the present invention discloses a telephoto lens, comprising a first lens 1, an aperture 7, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6, which are arranged in sequence along an optical axis from the object side to the image side. The first lens 1 is a front lens group, and the second lens 2 to the sixth lens 6 are a rear lens group.

[0080] The first to sixth lenses 6 each include an object-side surface facing the object side and allowing imaging light to pass therethrough, and an image-side surface facing the image side and allowing imaging light to pass therethrough.

[0081] The first lens 1 has a negative refractive power, and the object side surface of the first lens 1 is convex, and the image side surface is concave;

[0082] The second lens element 2 has positive refractive power, and the object side surface of the second lens element 2 is convex near the optical axis, and the image side surface is convex;

[0083] The third lens element 3 has a negative refractive power, and the object side surface of the third lens element 3 is convex, and the image side surface is concave;

[0084] The fourth lens element 4 has positive refractive power, and the object-side surface and image-side surface of the fourth lens element 4 are convex.

[0085] The fifth lens element 5 has a negative refractive power, and the object-side surface of the fifth lens element 5 is concave, and the image-side surface is convex;

[0086] The sixth lens element 6 has positive refractive power, and the object-side surface of the sixth lens element 6 is convex near the optical axis, and the image-side surface of the sixth lens element 6 is concave near the optical axis.

[0087] The detailed optical data of this specific embodiment are shown in Table 1-1.

[0088] Table 1-1 Detailed optical data of Example 1

[0089]

[0090]

[0091] In this embodiment, specific values ​​of some lens parameters are shown in Table 1-2.

[0092] Table 1-2 Partial lens parameters of Example 1

[0093] parameter CT2+CT3+CT4+CT5+CT6 6.315 TTL / AAG 3.976 AAG / BFL 1.04 IMH / EFL 0.511

[0094] In this embodiment, the first to sixth lenses are all plastic aspheric lenses. The equation for the surface curve of the aspheric lens is expressed as follows:

[0095]

[0096] in,

[0097] z: Depth of the aspheric surface (the vertical distance between the point y away from the optical axis on the aspheric surface and the tangent plane tangent to the vertex on the optical axis of the aspheric surface);

[0098] c: the vertex curvature of the aspheric surface;

[0099] K: Conic Constant;

[0100] radial distance;

[0101] r n : normalization radius (NRADIUS);

[0102] u:r / r n ;

[0103] a m : mth order Q con Coefficient (is the m th Q con coefficient);

[0104] Q m con : mth order Q con Polynomial th Q con polynomial).

[0105] The aspheric surface data of this embodiment are shown in Table 1-3.

[0106] Table 1-3 Aspheric surface data of Example 1

[0107]

[0108] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 2 As can be seen from the figure, when the spatial frequency of this lens reaches 150lp / mm, the center MTF value is greater than 0.65 and the edge MTF value is greater than 0.4, the imaging quality is excellent and the resolution of the lens is high. Figure 3 As can be seen from the figure, the defocus curves of each field of view of this lens under visible light are relatively concentrated, and the defocus amount is small. For the lateral chromatic aberration diagram of the lens under visible light, please refer to Figure 4 As can be seen from the figure, the lateral chromatic aberration is less than 2um, the chromatic aberration is small, and the image color reproduction is high. For the longitudinal chromatic aberration curve of the lens under visible light, please refer to Figure 5 As can be seen from the figure, the axial chromatic aberration is less than ±0.03mm, the color reproduction is good, the color difference is small, and the blue-purple fringing phenomenon is not obvious. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 6 ,As can be seen from the figure, the optical distortion is <2%, ,which is small and effectively improves the image quality.

[0109] Example 2

[0110] like Figure 7 As shown, the present embodiment is different from the embodiment 1 mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0111] The detailed optical data of this specific embodiment are shown in Table 2-1.

[0112] Table 2-1 Detailed optical data of Example 2

[0113]

[0114]

[0115] In this embodiment, specific values ​​of some lens parameters are shown in Table 2-2.

[0116] Table 2-2 Partial lens parameters of Example 2

[0117] parameter CT2+CT3+CT4+CT5+CT6 6.288 TTL / AAG 3.987 AAG / BFL 1.036 IMH / EFL 0.521

[0118] In this embodiment, the first to sixth lenses are all plastic aspheric lenses. The aspheric surface data of this embodiment are shown in Table 2-3.

[0119] Table 2-3 Aspheric surface data of Example 2

[0120]

[0121] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 8 As can be seen from the figure, when the spatial frequency of this lens reaches 150lp / mm, the center MTF value is greater than 0.65 and the edge MTF value is greater than 0.4, the imaging quality is excellent and the resolution of the lens is high. Figure 9 As can be seen from the figure, the defocus curves of each field of view of this lens under visible light are relatively concentrated, and the defocus amount is small. For the lateral chromatic aberration diagram of the lens under visible light, please refer to Figure 10 As can be seen from the figure, the lateral chromatic aberration is less than 2um, the chromatic aberration is small, and the image color reproduction is high. For the longitudinal chromatic aberration curve of the lens under visible light, please refer to Figure 11 As can be seen from the figure, the axial chromatic aberration is less than ±0.04mm, the color reproduction is good, the color difference is small, and the blue-purple fringing phenomenon is not obvious. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 12 ,As can be seen from the figure, the optical distortion is <3%, ,which is small and effectively improves the image quality.

[0122] Example 3

[0123] like Figure 13 As shown, the present embodiment is different from the embodiment 1 mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0124] The detailed optical data of this specific embodiment are shown in Table 3-1.

[0125] Table 3-1 Detailed optical data of Example 3

[0126]

[0127] In this embodiment, specific values ​​of some lens parameters are shown in Table 3-2.

[0128] Table 3-2 Partial lens parameters of Example 3

[0129] parameter CT2+CT3+CT4+CT5+CT6 6.203 TTL / AAG 4.499 AAG / BFL 0.863 IMH / EFL 0.518

[0130] In this embodiment, the first to sixth lenses are all plastic aspheric lenses. The aspheric surface data of this embodiment are shown in Table 3-3.

[0131] Table 3-3 Aspheric surface data of Example 3

[0132]

[0133] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 14As can be seen from the figure, when the spatial frequency of this lens reaches 150lp / mm, the center MTF value is greater than 0.65 and the edge MTF value is greater than 0.4, the imaging quality is excellent and the resolution of the lens is high. Figure 15 As can be seen from the figure, the defocus curves of each field of view of this lens under visible light are relatively concentrated, and the defocus amount is small. For the lateral chromatic aberration diagram of the lens under visible light, please refer to Figure 16 As can be seen from the figure, the lateral chromatic aberration is less than 2um, the chromatic aberration is small, and the image color reproduction is high. For the longitudinal chromatic aberration curve of the lens under visible light, please refer to Figure 17 As can be seen from the figure, the axial chromatic aberration is less than ±0.06mm, the color reproduction is good, the color difference is small, and the blue-purple fringing phenomenon is not obvious. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 18 ,As can be seen from the figure, the optical distortion is <3%, ,which is small and effectively improves the image quality.

[0134] Example 4

[0135] like Figure 19 As shown, the present embodiment is different from the embodiment 1 mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0136] The detailed optical data of this specific embodiment are shown in Table 4-1.

[0137] Table 4-1 Detailed optical data of Example 4

[0138]

[0139]

[0140] In this embodiment, specific values ​​of some lens parameters are shown in Table 4-2.

[0141] Table 4-2 Partial lens parameters of Example 4

[0142] parameter CT2+CT3+CT4+CT5+CT6 6.364 TTL / AAG 4.274 AAG / BFL 1.003 IMH / EFL 0.531

[0143] In this embodiment, the first to sixth lenses are all plastic aspheric lenses. The aspheric surface data of this embodiment are shown in Table 4-3.

[0144] Table 4-3 Aspheric surface data of Example 4

[0145]

[0146] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 20As can be seen from the figure, when the spatial frequency of this lens reaches 150lp / mm, the center MTF value is greater than 0.65 and the edge MTF value is greater than 0.4, the imaging quality is excellent and the resolution of the lens is high. Figure 21 As can be seen from the figure, the defocus curves of each field of view of this lens under visible light are relatively concentrated, and the defocus amount is small. For the lateral chromatic aberration diagram of the lens under visible light, please refer to Figure 22 As can be seen from the figure, the lateral chromatic aberration is less than 3um, the chromatic aberration is small, and the image color reproduction is high. For the longitudinal chromatic aberration curve of the lens under visible light, please refer to Figure 23 As can be seen from the figure, the axial chromatic aberration is less than ±0.06mm, the color reproduction is good, the color difference is small, and the blue-purple fringing phenomenon is not obvious. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 24 ,As can be seen from the figure, the optical distortion is <5%, ,which is small and effectively improves the image quality.

[0147] Example 5

[0148] like Figure 25 As shown, the present embodiment is different from the embodiment 1 mainly in optical parameters such as the curvature radius of each lens surface and the lens thickness.

[0149] The detailed optical data of this specific embodiment are shown in Table 5-1.

[0150] Table 5-1 Detailed optical data of Example 5

[0151]

[0152] In this embodiment, specific values ​​of some lens parameters are shown in Table 5-2.

[0153] Table 5-2 Partial lens parameters of Example 5

[0154] parameter CT2+CT3+CT4+CT5+CT6 5.698 TTL / AAG 3.854 AAG / BFL 1.063 IMH / EFL 0.534

[0155] In this embodiment, the first to sixth lenses are all plastic aspheric lenses. The aspheric surface data of this embodiment are shown in Table 5-3.

[0156] Table 5-3 Aspheric surface data of Example 5

[0157]

[0158] In this embodiment, please refer to the MTF curve of the lens under visible light. Figure 26As can be seen from the figure, when the spatial frequency of this lens reaches 150lp / mm, the center MTF value is greater than 0.65 and the edge MTF value is greater than 0.4, the imaging quality is excellent and the resolution of the lens is high. Figure 27 As can be seen from the figure, the defocus curves of each field of view of this lens under visible light are relatively concentrated, and the defocus amount is small. For the lateral chromatic aberration diagram of the lens under visible light, please refer to Figure 28 As can be seen from the figure, the lateral chromatic aberration is less than 2um, the chromatic aberration is small, and the image color reproduction is high. For the longitudinal chromatic aberration curve of the lens under visible light, please refer to Figure 29 As can be seen from the figure, the axial chromatic aberration is less than ±0.06mm, the color reproduction is good, the color difference is small, and the blue-purple fringing phenomenon is not obvious. For the field curvature and distortion diagram of the lens under visible light, please refer to Figure 30 ,As can be seen from the figure, the optical distortion is <5%, ,which is small and effectively improves the image quality.

[0159] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A telephoto lens, characterized in that: It includes a first lens, an aperture stop, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along an optical axis from the object side to the image side. Each of the first lens to the sixth lens includes an object side facing the object side through which imaging light passes and an image side facing the image side through which imaging light passes; The first lens has a negative refractive power, and the object side of the first lens is convex and the image side is concave; The second lens has a positive refractive power, and the object side of the second lens is convex near the optical axis and the image side is convex; The third lens has a negative refractive power, and the object side of the third lens is convex and the image side is concave; The fourth lens has a positive refractive power, and the object side of the fourth lens is convex and the image side is convex; The fifth lens has a negative refractive power, and the object side of the fifth lens is concave and the image side is convex; The sixth lens has a positive refractive power, and the object side of the sixth lens is convex near the optical axis and the image side is concave near the optical axis; Among them, the first lens to the sixth lens are all plastic aspherical lenses; This lens satisfies: -30mm < f1 < -27mm, 6mm < f2 < 8mm, -9mm < f3 < -7.5mm, 5.5mm < f4 < 8mm, -10mm < f5 < -8.5mm, 8mm < f6 < 9.5mm. Among them, f1, f2, f3, f4, f5, f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively.

2. The telephoto lens according to claim 1, wherein: This lens satisfies: 3 < |f1 / f| < 4, 0.5 < |f2 / f| < 1, 0.5 < |f3 / f| < 1.5, 0.5 < |f4 / f| < 1.5, 1 < |f5 / f| < 2, 0.5 < |f6 / f| < 1.

5. Among them, f is the overall focal length value of this lens, and f1, f2, f3, f4, f5, f6 are the focal length values of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively.

3. The telephoto lens according to claim 1, wherein: This lens satisfies: 6mm < CT2 + CT3 + CT4 + CT5 + CT6 < 7mm. Among them, CT2, CT3, CT4, CT5, CT6 are the central thicknesses of the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens respectively.

4. The telephoto lens according to claim 1, wherein: This lens satisfies: 3.5 ≤ TTL / AAG ≤ 4.5, where TTL is the overall optical length of the lens, and AAG is the sum of the air gaps between adjacent two lenses of the first to the sixth lenses on the optical axis.

5. The telephoto lens according to claim 1 or 4, wherein: [[ID=--]]The overall optical length TTL of this lens satisfies: TTL < 15mm.

6. The telephoto lens according to claim 1, wherein: This lens satisfies: 0.8 ≤ AAG / BFL ≤ 1.5, where AAG is the sum of the air gaps between adjacent two lenses of the first to the sixth lenses on the optical axis, and BFL is the distance from the image side of the sixth lens to the imaging plane of the lens on the optical axis.

7. The telephoto lens according to claim 1, wherein: This lens satisfies: 0.45 ≤ IMH / EFL ≤ 0.6, where IMH is the semi-image height on the image side of the lens, and EFL is the effective focal length of the lens.

8. The telephoto lens according to claim 1 or 7, wherein: The effective focal length EFL of this lens satisfies: 7.45mm < EFL < 8.0mm.

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