A telephoto floating focus lens

Abstract

The present invention provides a telephoto floating focus lens, comprising 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, arranged in sequence along an optical axis from the object side to the image side. The second lens and the third lens constitute lens group one, and the fourth lens and the fifth lens constitute lens group two. The seventh lens and the eighth lens are floating lenses. The first lens and the eighth lens are both glass spherical lenses. The first lens to the sixth lens constitute the front lens group, and the seventh lens and the eighth lens constitute the rear lens group. Firstly, focusing at different object distances is achieved by the floating movement of the seventh lens and the eighth lens. Secondly, by rationally allocating the positions and gluing relationships of the various lenses constituting the lens group, the optical structure can be optimized, lens distortion can be reduced, and lens structure design and assembly are more favorable. Thirdly, the eight-piece design makes the lens compact and easy to install and use.

Description

Technical Field

[0001] This invention relates to the field of telephoto lens technology, and more specifically to a telephoto floating focusing lens. Background Technology

[0002] Most existing telephoto floating focus lenses have one or more of the following defects: First, the optical TTL is too large and there are too many lens elements, which makes the overall cost and weight of the lens too high and limits its installation and use; Second, the distortion is large, which makes it difficult to produce post-processing algorithms; Third, the depth of field of telephoto lenses is small, which makes it impossible to meet the imaging requirements of different object distances. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to propose a telephoto floating focusing lens. By adopting an eight-element lens architecture, and by rationally allocating the optical power of each lens element, optimizing the surface shape, thickness and distance between each lens element, the lens can achieve good image quality, thereby solving the problems mentioned in the background section above.

[0004] This invention is achieved through the following technical solution:

[0005] A telephoto floating focusing lens 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 arranged sequentially along the optical axis from the object side to the image side. The second lens and the third lens form a lens group one, and the fourth lens and the fifth lens form a lens group two. The seventh lens and the eighth lens are floating lenses. The first lens and the eighth lens are both glass spherical lenses. The first to sixth lenses form the front group of the lens, and the seventh and eighth lenses form the rear group of the lens.

[0006] in:

[0007] The object-side surface of the first lens is convex, the image-side surface of the first lens is concave, and the first lens has positive optical power.

[0008] The object-side surface of the second lens is convex, the image-side surface of the second lens is concave, and the second lens has negative optical power.

[0009] The object-side surface of the third lens is convex, the image-side surface of the third lens is convex or flat, and the third lens has positive optical power.

[0010] The object side of the fourth lens is convex, the image side of the fourth lens is convex, and the fourth lens has positive optical power.

[0011] The object-side surface of the fifth lens is concave, the image-side surface of the fifth lens is concave, and the fifth lens has negative optical power.

[0012] The object-side surface of the sixth lens is convex, the image-side surface of the sixth lens is concave, and the sixth lens has negative optical power.

[0013] The object-side surface of the seventh lens is convex, the image-side surface of the seventh lens is convex, and the seventh lens has positive optical power.

[0014] The object side of the eighth lens is concave, the image side of the eighth lens is concave, and the seventh lens has negative optical power.

[0015] The beneficial effects of this embodiment are as follows: First, focusing at different object distances is achieved through the floating of the seventh and eighth lenses; second, by rationally allocating the positions and bonding relationships of the lens groups, the optical structure can be optimized, lens distortion can be reduced, and lens structure design and assembly are more favorable; third, the eight-element design results in a small overall lens size and convenient installation and use; fourth, lens distortion is within 0.5%, which can well reproduce the shape of objects; fifth, due to the floating of the seventh and eighth lenses, a semi-floating focusing method can ensure 10 The lens exhibits good image quality at object distances from m to infinity. Sixthly, when used with a 1 / 1.8″ sensor, the MTF (Mean Transmission Count) is greater than 0.5 at 93 lp / mm at object distances from 10 m to infinity, demonstrating good image quality. It employs an eight-element glass spherical lens design with a reasonable allocation of cemented glass lenses, which optimizes the optical structure, reduces lens distortion, and facilitates lens structure design and assembly. Furthermore, when the object distance changes, the system focuses by controlling the forward and backward movement of the seventh and eighth lenses.

[0016] Furthermore,

[0017] The lens satisfies the following relationship: the combined focal length of the first lens to the eighth lens is 79mm≤EFL≤80mm, Fno=2.7, and the total optical system length TTL of the lens is ≤75mm.

[0018] The beneficial effects of this embodiment are: the total length (TTL) of the lens's optical system is less than 75mm, the overall size of the lens is small, and it is convenient to install and use; the overall field of view of the lens is large, the structure is compact, and it is highly practical.

[0019] Furthermore,

[0020] The absolute value of the focal length |F1| of the first lens satisfies the following relationship: 64mm≤|F1|≤72mm;

[0021] The absolute value of the focal length |F2| of the second lens satisfies the following relationship: 41mm≤|F2|≤44mm;

[0022] The absolute value of the focal length |F3| of the third lens satisfies the following relationship: 36mm≤|F3|≤38mm;

[0023] The absolute value of the focal length |F4| of the fourth lens satisfies the following relationship: 33mm≤|F4|≤37mm;

[0024] The absolute value of the focal length |F5| of the fifth lens satisfies the following relationship: 49mm≤|F5|≤58mm;

[0025] The absolute value of the focal length |F6| of the sixth lens satisfies the following relationship: 27mm≤|F6|≤31mm;

[0026] The absolute value of the focal length |F7| of the seventh lens satisfies the following relationship: 21mm≤|F7|≤24mm;

[0027] The absolute value of the focal length |F8| of the eighth lens satisfies the following relationship: 19mm≤|F8|≤21.5mm.

[0028] The beneficial effect of this embodiment is that it further reduces the focal length of each lens, making the lens structure more compact.

[0029] Furthermore,

[0030] The absolute value of the ratio of the focal length F1 of the first lens to the overall focal length F of the lens satisfies the following relationship: 0.8≤|F1 / F|≤1;

[0031] The absolute value of the ratio of the focal length F2 of the second lens to the overall focal length F of the lens satisfies the following relationship: 0.5≤|F2 / F|≤0.6;

[0032] The absolute value of the ratio of the focal length F3 of the third lens to the overall focal length F of the lens satisfies the following relationship: 0.4≤|F3 / F|≤0.5;

[0033] The absolute value of the ratio of the focal length F4 of the fourth lens to the overall focal length F of the lens satisfies the following relationship: 0.4≤|F4 / F|≤0.5;

[0034] The absolute value of the ratio of the focal length F5 of the fifth lens to the overall focal length F of the lens satisfies the following relationship: 0.6≤|F5 / F|≤0.8;

[0035] The absolute value of the ratio of the focal length F6 of the sixth lens to the overall focal length F of the lens satisfies the following relationship: 0.3≤|F6 / F|≤0.4;

[0036] The absolute value of the ratio of the focal length F7 of the seventh lens to the overall focal length F of the lens satisfies the following relationship: 0.2≤|F7 / F|≤0.3;

[0037] The absolute value of the ratio of the focal length F8 of the eighth lens to the overall focal length F of the lens satisfies the following relationship: 0.2≤|F8 / F|≤0.3.

[0038] The beneficial effect of this embodiment is that it further reduces the combined focal length of the lenses, making the lens structure more compact.

[0039] Furthermore,

[0040] The lens satisfies the following relationship: D1 / TTL≤0.4, where D1 is the effective aperture of the first lens and TTL is the total length of the lens's optical system.

[0041] The beneficial effect of this embodiment is that it satisfies the above formula range and can effectively control the lens size.

[0042] Furthermore,

[0043] The lens satisfies the following relationship: 0.9≤TTL / f≤1.0, where TTL is the total length of the lens's optical system and f is the effective focal length of the lens.

[0044] The beneficial effects of this embodiment are: satisfying the above formula range helps to control the overall length of the lens, so as to realize the miniaturization of the lens's optical system and facilitate the subsequent installation and use of the lens.

[0045] Furthermore,

[0046] The lens satisfies the following relationship: 0.015≤L / f≤0.02, where L is the focusing distance that the floating group composed of the seventh and eighth lenses moves from an object distance of infinity to an object distance of 10 meters, and f is the effective focal length of the lens.

[0047] The beneficial effects of this embodiment are: satisfying the above formula range can effectively reduce the size of the lens group, avoid the optical lens group being too large, and at the same time improve the focusing accuracy of the lens.

[0048] Furthermore,

[0049] The lens satisfies the following relationship: 1.0≤|fa / fb|≤2.0, where fa is the combined focal length of the first to sixth lenses, and fb is the combined focal length of the seventh and eighth lenses.

[0050] The beneficial effect of this embodiment is that satisfying the above formula helps to improve the optical MTF performance of the lens and better improve the resolution of the lens.

[0051] Furthermore,

[0052] An aperture stop is provided between the sixth lens and the seventh lens.

[0053] Furthermore,

[0054] Both the first lens and the eighth lens are glass spherical lenses. The first to sixth lenses form the front group of the lens, and the seventh and eighth lenses form the rear group of the lens.

[0055] The beneficial effects of this embodiment are as follows: by adopting an eight-glass spherical lens design and rationally allocating the positions of the glass cemented lenses, the optical structure can be optimized, lens distortion can be reduced, and the lens structure design and assembly can be improved; and when the object distance changes, the system can be focused by controlling the forward and backward movement of the seventh and eighth lenses. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the optical path in Embodiment 1 of the present invention.

[0057] Figure 2 This is the MTF curve of the lens at infinity in Example 1.

[0058] Figure 3 This is the MTF curve of the lens in Example 1 at an object distance of 10 meters.

[0059] Figure 4 This is a defocus curve of the lens at infinity object distance in Example 1.

[0060] Figure 5 This is a defocus curve of the lens at an object distance of 10 meters in Example 1.

[0061] Figure 6 This is a lateral chromatic aberration curve of the lens in Example 1 under visible light 435nm-650nm.

[0062] Figure 7 This is a longitudinal chromatic difference curve of the lens in Example 1 under visible light 435nm-650nm.

[0063] Figure 8 The image shows the field curvature and distortion of the lens in Example 1 under visible light (435nm-650nm).

[0064] Figure 9 This is a schematic diagram of the optical path in Embodiment 2 of the present invention.

[0065] Figure 10 This is the MTF curve of the lens at infinity in Example 2.

[0066] Figure 11 This is the MTF curve of the lens at a distance of 10 meters in Example 2.

[0067] Figure 12This is a defocus curve of the lens at infinity object distance in Example 2.

[0068] Figure 13 This is a defocus curve of the lens at an object distance of 10 meters in Example 2.

[0069] Figure 14 This is a lateral chromatic aberration curve of the lens in Example 2 under visible light 435nm-650nm.

[0070] Figure 15 This is a longitudinal chromatic difference curve of the lens in Example 2 under visible light 435nm-650nm.

[0071] Figure 16 The image shows the field curvature and distortion of the lens in Example 2 under visible light (435nm-650nm).

[0072] Figure 17 This is a schematic diagram of the optical path in Embodiment 3 of the present invention.

[0073] Figure 18 This is the MTF curve of the lens at infinity in Example 3.

[0074] Figure 19 This is the MTF curve of the lens in Example 3 at an object distance of 10 meters.

[0075] Figure 20 This is a defocus curve of the lens at infinity object distance in Example 3.

[0076] Figure 21 This is a defocus curve of the lens at an object distance of 10 meters in Example 3.

[0077] Figure 22 This is a lateral chromatic aberration curve of the lens in Example 3 under visible light 435nm-650nm.

[0078] Figure 23 This is a longitudinal chromatic difference curve of the lens in Example 3 under visible light 435nm-650nm.

[0079] Figure 24 The image shows the field curvature and distortion of the lens in Example 3 under visible light (435nm-650nm).

[0080] The above figures include the following reference numerals:

[0081] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Aperture stop. Detailed Implementation

[0082] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0083] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0084] Reference Figures 1 to 24 As shown, a telephoto floating focusing lens includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, and an eighth lens 8 arranged sequentially along the optical axis from the object side to the image side. The second lens 2 and the third lens 3 are cemented together to form a lens group one, the fourth lens 4 and the fifth lens 5 are cemented together to form a lens group two, the seventh lens 7 and the eighth lens 8 are a floating lens group, and an aperture stop 9 is provided between the sixth lens 6 and the seventh lens 7.

[0085] in:

[0086] The object-side surface of the first lens 1 is convex, the image-side surface of the first lens 1 is concave, and the first lens 1 has positive optical power.

[0087] The object-side surface of the second lens 2 is convex, the image-side surface of the second lens 2 is concave, and the second lens 2 has negative optical power.

[0088] The object side of the third lens 3 is convex, the image side of the third lens 3 is convex or flat, and the third lens 3 has positive optical power.

[0089] The object side of the fourth lens 4 is convex, the image side of the fourth lens 4 is convex, and the fourth lens 4 has positive optical power.

[0090] The object-side surface of the fifth lens 5 is concave, the image-side surface of the fifth lens 5 is concave, and the fifth lens 5 has negative optical power.

[0091] The object-side surface of the sixth lens 6 is convex, the image-side surface of the sixth lens 6 is concave, and the sixth lens 6 has negative optical power.

[0092] The object-side surface of the seventh lens 7 is convex, the image-side surface of the seventh lens 7 is convex, and the seventh lens 7 has positive optical power;

[0093] The object side of the eighth lens 8 is concave, the image side of the eighth lens 8 is concave, and the seventh lens 7 has negative optical power.

[0094] The beneficial effects of this embodiment are as follows: First, when the object distance changes, focusing at different object distances is achieved through the floating of the seventh lens 7 and the eighth lens 8; Second, by rationally allocating the positions and bonding relationships of the lens groups, the optical structure can be optimized, lens distortion can be reduced, and the lens structure design and assembly can be improved; Third, the design of eight glass spherical lenses results in a small overall lens size and convenient installation and use; Fourth, the lens distortion is within 0.5%, which can well reproduce the shape of objects; Fifth, due to the floating of the seventh lens 7 and the eighth lens 8, a semi-group floating focusing method can be adopted, which can ensure good image quality at object distances from 10m to infinity; Sixth, when the lens of this invention is used with a 1 / 1.8″ sensor, the MTF is greater than 0.5 at 93lp / mm at object distances from 10m to infinity, indicating that the lens has good image quality.

[0095] Furthermore,

[0096] The lens satisfies the following relationship: the combined focal length of the first lens 1 to the eighth lens 8 is 79mm≤EFL≤80mm, Fno=2.7, and the total optical system length TTL of the lens is ≤75mm.

[0097] The beneficial effects of this embodiment are: the total length (TTL) of the lens's optical system is less than 75mm, the overall size of the lens is small, and it is convenient to install and use; the overall field of view of the lens is large, the structure is compact, and it is highly practical.

[0098] Furthermore,

[0099] The absolute value of the focal length |F1| of the first lens 1 satisfies the following relationship: 64mm≤|F1|≤72mm;

[0100] The absolute value of the focal length |F2| of the second lens 2 satisfies the following relationship: 41mm≤|F2|≤44mm;

[0101] The absolute value of the focal length |F3| of the third lens 3 satisfies the following relationship: 36mm≤|F3|≤38mm;

[0102] The absolute value of the focal length |F4| of the fourth lens 4 satisfies the following relationship: 33mm≤|F4|≤37mm;

[0103] The absolute value of the focal length |F5| of the fifth lens 5 satisfies the following relationship: 49mm≤|F5|≤58mm;

[0104] The absolute value of the focal length |F6| of the sixth lens 6 satisfies the following relationship: 27mm≤|F6|≤31mm;

[0105] The absolute value of the focal length |F7| of the seventh lens 7 satisfies the following relationship: 21mm≤|F7|≤24mm;

[0106] The absolute value of the focal length |F8| of the eighth lens 8 satisfies the following relationship: 19mm≤|F8|≤21.5mm.

[0107] The beneficial effect of this embodiment is that it further reduces the focal length of each lens, making the lens structure more compact.

[0108] Furthermore,

[0109] The absolute value of the ratio of the focal length F1 of the first lens 1 to the overall focal length F of the lens satisfies the following relationship: 0.8≤|F1 / F|≤1;

[0110] The absolute value of the ratio of the focal length F2 of the second lens 2 to the overall focal length F of the lens satisfies the following relationship: 0.5≤|F2 / F|≤0.6;

[0111] The absolute value of the ratio of the focal length F3 of the third lens 3 to the overall focal length F of the lens satisfies the following relationship: 0.4≤|F3 / F|≤0.5;

[0112] The absolute value of the ratio of the focal length F4 of the fourth lens 4 to the overall focal length F of the lens satisfies the following relationship: 0.4≤|F4 / F|≤0.5;

[0113] The absolute value of the ratio of the focal length F5 of the fifth lens 5 to the overall focal length F of the lens satisfies the following relationship: 0.6≤|F5 / F|≤0.8;

[0114] The absolute value of the ratio of the focal length F6 of the sixth lens 6 to the overall focal length F of the lens satisfies the following relationship: 0.3≤|F6 / F|≤0.4;

[0115] The absolute value of the ratio of the focal length F7 of the seventh lens 7 to the overall focal length F of the lens satisfies the following relationship: 0.2≤|F7 / F|≤0.3;

[0116] The absolute value of the ratio of the focal length F8 of the eighth lens 8 to the overall focal length F of the lens satisfies the following relationship: 0.2≤|F8 / F|≤0.3.

[0117] The beneficial effect of this embodiment is that it further reduces the combined focal length of the lenses, making the lens structure more compact.

[0118] Furthermore,

[0119] The lens satisfies the following relationship: D1 / TTL≤0.4, where D1 is the effective aperture of the first lens 1 and TTL is the total length of the lens's optical system.

[0120] The beneficial effect of this embodiment is that it satisfies the above formula range and can effectively control the lens size.

[0121] Furthermore,

[0122] The lens satisfies the following relationship: 0.9≤TTL / f≤1.0, where TTL is the total length of the lens's optical system and f is the effective focal length of the lens.

[0123] The beneficial effects of this embodiment are: satisfying the above formula range helps to control the overall length of the lens, so as to realize the miniaturization of the lens's optical system and facilitate the subsequent installation and use of the lens.

[0124] Furthermore,

[0125] The lens satisfies the following relationship: 0.015≤L / f≤0.02, where L is the focusing distance that the floating group composed of the seventh lens 7 and the eighth lens 8 moves from an object distance of infinity to an object distance of 10 meters, and f is the effective focal length of the lens.

[0126] The beneficial effects of this embodiment are: satisfying the above formula range can effectively reduce the size of the lens group, avoid the optical lens group being too large, and at the same time improve the focusing accuracy of the lens.

[0127] Furthermore,

[0128] The lens satisfies the following relationship: 1.0≤|fa / Pb|≤2.0, where fa is the combined focal length of the first lens 1 to the sixth lens 6, and fb is the combined focal length of the seventh lens 7 and the eighth lens 8.

[0129] The beneficial effect of this embodiment is that satisfying the above formula helps to improve the optical MTF performance of the lens and better improve the resolution of the lens.

[0130] The present invention provides detailed optical data for embodiments one to three, as shown in Tables 1-1 to 1-3.

[0131] The conditional expressions for Examples 1 to 3 are as follows:

[0132] Conditional expression Example 1 Example 2 Example 3 F 79.592 79.517 79.368 TTL 75 75 75 Fno 2.70 2.70 2.70 IMH 8.800 8.800 8.800 1.0<|fa / fb|<2.0 1.676 1.590 1.357 0.1<D1 / TTL<0.15 0.390 0.390 0.390 0.1<f / IMH<0.15 0.942 0.943 0.945 1.3<L / f<1.6 0.017 0.019 0.019

[0133] Detailed optical data in Table 1-1

[0134]

[0135] Detailed optical data in Table 1-2

[0136]

[0137] Detailed optical data in Table 1-3

[0138]

[0139] Figure 2 The image shows the MTF curve of the lens in Example 1 at an infinity object distance. As can be seen from the figure, the MTF of the lens at an infinity object distance is greater than 0.5 at 93 lp / mm, indicating excellent image quality and high lens resolution.

[0140] Figure 3 The image shows the MTF curve of the lens in Example 1 at an object distance of 10 meters. As can be seen from the figure, the lens has an MTF greater than 0.5 at 93 lp / mm at a 10m object distance, indicating excellent image quality and high lens resolution.

[0141] Figure 4 This is a defocus curve diagram of the lens at infinity object distance in Example 1. As can be seen from the diagram, the defocus curves of the lens in each field of view are relatively concentrated at infinity object distance, indicating a small defocus amount.

[0142] Figure 5 This is a defocus curve diagram of the lens in Example 1 at an object distance of 10 meters. As can be seen from the figure, the defocus curves of the lens in various fields of view are relatively concentrated at an object distance of 10 meters, and the defocus amount is small.

[0143] Figure 6 This is a lateral chromatic aberration curve of the lens in Example 1 under visible light (435nm-650nm). The figure shows that the lens chromatic aberration is within 2µm, exhibiting high color fidelity, and the blue-purple fringing is well corrected.

[0144] Figure 7 This is a longitudinal chromatic aberration curve of the lens in Example 1 under visible light (435nm-650nm). The graph shows that the lens exhibits small chromatic aberration along its axis, resulting in good color reproduction, minimal color difference, and minimal blue-violet fringing.

[0145] Figure 8The image shows the field curvature and distortion of the lens in Example 1 within the visible light range of 435nm-650nm. As can be seen from the image, the lens exhibits good control over field curvature and distortion at various wavelengths, effectively improving image quality and facilitating subsequent image correction.

[0146] Figure 10 The image shows the MTF curve of the lens in Example 2 at an infinity object distance. As can be seen from the figure, the MTF of the lens at an infinity object distance is greater than 0.5 at 93 lp / mm, indicating excellent image quality and high lens resolution.

[0147] Figure 11 The image shows the MTF curve of the lens in Example 2 at an object distance of 10 meters. As can be seen from the figure, the lens has an MTF greater than 0.5 at 93 lp / mm at an object distance of 10 meters, indicating excellent image quality and high lens resolution.

[0148] Figure 12 This is a defocus curve diagram of the lens at infinity object distance in Example 2. As can be seen from the diagram, the defocus curves of the lens in each field of view are relatively concentrated at infinity object distance, indicating a small defocus amount.

[0149] Figure 13 This is a defocus curve diagram of the lens in Example 2 at an object distance of 10 meters. As can be seen from the diagram, the defocus curves of the lens in each field of view are relatively concentrated at an object distance of 10 meters, indicating a small defocus amount.

[0150] Figure 14 This is a lateral chromatic aberration curve of the lens in Example 2 under visible light (435nm-650nm). The figure shows that the lens chromatic aberration is within 2µm, exhibiting high color fidelity, and the blue-purple fringing is well corrected.

[0151] Figure 15 This is a longitudinal chromatic aberration curve of the lens in Example 2 within the visible light range of 435nm-650nm. The graph shows that the lens exhibits small chromatic aberration along its axis, resulting in good color reproduction, minimal color difference, and minimal blue-violet fringing.

[0152] Figure 16 The image shows the field curvature and distortion of the lens in Example 2 within the visible light range of 435nm-650nm. As can be seen from the image, the lens exhibits good control over field curvature and distortion at various wavelengths, effectively improving image quality and facilitating subsequent image correction.

[0153] Figure 18 The image shows the MTF curve of the lens in Example 3 at an infinity object distance. As can be seen from the figure, the MTF of the lens at an infinity object distance is greater than 0.5 at 93 lp / mm, indicating excellent image quality and high lens resolution.

[0154] Figure 19The image shows the MTF curve of the lens in Example 3 at an object distance of 10 meters. As can be seen from the figure, the lens has an MTF greater than 0.5 at 93 lp / mm at an object distance of 10 meters, indicating excellent image quality and high lens resolution.

[0155] Figure 20 This is a defocus curve diagram of the lens at infinity object distance in Example 3. As can be seen from the diagram, the defocus curves of the lens in each field of view are relatively concentrated at infinity object distance, indicating a small defocus amount.

[0156] Figure 21 This is a defocus curve diagram of the lens in Example 3 at an object distance of 10 meters. As can be seen from the diagram, the defocus curves of the lens in each field of view are relatively concentrated at an object distance of 10 meters, indicating a small defocus amount.

[0157] Figure 22 This is a lateral chromatic aberration curve of the lens in Example 3 under visible light (435nm-650nm). The figure shows that the lens chromatic aberration is within 2µm, exhibiting high color fidelity and well-corrected blue-violet fringing.

[0158] Figure 23 This is a longitudinal chromatic aberration curve of the lens in Example 3 under visible light (435nm-650nm). The graph shows that the lens exhibits small chromatic aberration along its axis, resulting in good color reproduction, minimal color difference, and minimal blue-purple fringing.

[0159] Figure 24 The image shows the field curvature and distortion of the lens in Example 3 within the visible light range of 435nm-650nm. As can be seen from the image, the lens exhibits good control over field curvature and distortion at various wavelengths, effectively improving image quality and facilitating subsequent image correction.

[0160] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A telephoto floating focusing lens, characterized in that: The system 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 arranged sequentially along the optical axis from the object side to the image side. The second lens and the third lens are cemented together to form lens group one, the fourth lens and the fifth lens are cemented together to form lens group two, and the seventh lens and the eighth lens are floating lenses. The object-side surface of the first lens is convex, the image-side surface of the first lens is concave, and the first lens has positive optical power. The object-side surface of the second lens is convex, the image-side surface of the second lens is concave, and the second lens has negative optical power. The object-side surface of the third lens is convex, the image-side surface of the third lens is convex or flat, and the third lens has positive optical power. The object side of the fourth lens is convex, the image side of the fourth lens is convex, and the fourth lens has positive optical power. The object-side surface of the fifth lens is concave, the image-side surface of the fifth lens is concave, and the fifth lens has negative optical power. The object-side surface of the sixth lens is convex, the image-side surface of the sixth lens is concave, and the sixth lens has negative optical power. The object-side surface of the seventh lens is convex, the image-side surface of the seventh lens is convex, and the seventh lens has positive optical power. The object-side surface of the eighth lens is concave, the image-side surface of the eighth lens is concave, and the seventh lens has negative optical power. The lens satisfies the following relationship: the combined focal length of the first lens to the eighth lens is 79mm≤EFL≤80mm, Fno=2.7, and the total optical system length TTL of the lens is ≤75mm.

2. The telephoto floating focusing lens according to claim 1, characterized in that: absolute value of the focal length of the first lens The following relationship must be satisfied: 64mm≤ ≤72mm; absolute value of the focal length of the second lens The following relationship must be satisfied: 41mm≤ ≤44mm; The absolute value of the focal length of the third lens The following relationship must be satisfied: 36mm≤ ≤38mm; The absolute value of the focal length of the fourth lens The following relationship must be satisfied: 33mm≤ ≤37mm; The absolute value of the focal length of the fifth lens The following relationship must be satisfied: 49mm≤ ≤58mm; The absolute value of the focal length of the sixth lens The following relationship must be satisfied: 27 mm ≤ ≤31mm; The absolute value of the focal length of the seventh lens The following relationship must be satisfied: 21 mm ≤ ≤24mm; The absolute value of the focal length of the eighth lens The following relationship must be satisfied: 19mm≤ ≤21.5mm.

3. A telephoto floating focusing lens according to claim 1 or 2, characterized in that: The focal length of the first lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.8 ≤ / F ≤1; The focal length of the second lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.5 ≤ / F ≤0.6; The focal length of the third lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.4 ≤ / F ≤0.5; The focal length of the fourth lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.4 ≤ / F ≤0.5; The focal length of the fifth lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.6 ≤ / F ≤0.8; The focal length of the sixth lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.3 ≤ / F ≤0.4; The focal length of the seventh lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.2 ≤ / F ≤0.3; The focal length of the eighth lens The absolute value of the ratio to the overall focal length F of the lens satisfies the following relationship: 0.2 ≤ / F ≤0.

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4. A telephoto floating focusing lens according to claim 1, characterized in that: The lens satisfies the following relationship: / TTL≤0.4, where D1 is the effective aperture of the first lens of the lens, and TTL is the total length of the optical system of the lens.

5. A telephoto floating focusing lens according to claim 1, characterized in that: The lens satisfies the following relationship: 0.9≤TTL / f≤1.0, where TTL is the total length of the lens's optical system and f is the effective focal length of the lens.

6. A telephoto floating focusing lens according to claim 1, characterized in that: The lens satisfies the following relationship: 0.015≤L / f≤0.02, where L is the focusing distance that the floating group composed of the seventh and eighth lenses moves from an object distance of infinity to an object distance of 10 meters, and f is the effective focal length of the lens.

7. A telephoto floating focusing lens according to claim 1, characterized in that: The lens satisfies the following relationship: 1.0≤|fa / fb|≤2.0, where fa is the combined focal length of the first to sixth lenses, and fb is the combined focal length of the seventh and eighth lenses.

8. A telephoto floating focusing lens according to claim 1, characterized in that: An aperture stop is provided between the sixth lens and the seventh lens.

9. A telephoto floating focusing lens according to claim 1, characterized in that: Both the first lens and the eighth lens are glass spherical lenses. The first to sixth lenses form the front group of the lens, and the seventh and eighth lenses form the rear group of the lens.

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