CN114994880B

CN114994880B - Optical system, lens module and electronic equipment

Info

Publication number: CN114994880B
Application number: CN202210942458.3A
Authority: CN
Inventors: 邹金华
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-08-08
Filing date: 2022-08-08
Publication date: 2022-11-22
Anticipated expiration: 2042-08-08
Also published as: CN114994880A

Abstract

The invention relates to an optical system, a lens module and an electronic device. The optical system comprises a first lens element with positive refractive power, a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a concave image-side surface; a third lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a fourth lens element with refractive power having a convex image-side surface; a fifth lens element with refractive power having a convex image-side surface; a sixth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a seventh lens element with positive refractive power having a convex object-side surface and a concave image-side surface; an eighth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; the optical system satisfies: 5mm or more and 5.5mm or less of OAL/FNO. The optical system can give consideration to both good imaging quality and miniaturization design.

Description

Optical system, lens module and electronic equipment

Technical Field

The present invention relates to the field of camera shooting, and in particular, to an optical system, a lens module, and an electronic apparatus.

Background

With the rapid development of the camera technology, more and more electronic devices such as smart phones, tablet computers, electronic readers, and the like are equipped with a camera lens to realize an image capturing function. Accordingly, the requirements of users for the performance and the use experience of electronic devices are also increasing, and the electronic devices are required to have not only good imaging quality, but also to meet the requirement of miniaturization design. However, the current imaging lens generally increases in size while achieving good imaging quality, and it is difficult to achieve both good imaging quality and a compact design.

Disclosure of Invention

In view of the above, it is necessary to provide an optical system, a lens module, and an electronic apparatus, which are directed to the problem that it is difficult for the conventional imaging lens to achieve both good imaging quality and a compact design.

An optical system, wherein eight lenses having refractive power are provided, the optical system sequentially including, from an object side to an image side along an optical axis: a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a second lens element with negative refractive power having a concave image-side surface at a paraxial region; a third lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a fourth lens element with refractive power having a convex image-side surface at paraxial region; a fifth lens element with refractive power having a convex image-side surface at paraxial region; a sixth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a seventh lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; an eighth lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; and the optical system satisfies the following conditional expression: 5mm or more of OAL/FNO or less than 5.5mm; wherein OAL is the distance on the optical axis from the object side surface of the first lens to the image side surface of the eighth lens, and FNO is the f-number of the optical system. The optical system has the refractive power and the surface shape characteristics, satisfies the conditional expression, and has good imaging quality and miniaturization design.

A lens module includes a photosensitive element and the optical system of any of the above embodiments, where the photosensitive element is disposed on an image side of the optical system.

An electronic device comprises a shell and the lens module, wherein the lens module is arranged on the shell.

Drawings

FIG. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present application;

FIG. 2 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a first embodiment of the present application;

FIG. 3 is a schematic diagram of an optical system according to a second embodiment of the present application;

FIG. 4 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a second embodiment of the present application;

FIG. 5 is a schematic view of an optical system according to a third embodiment of the present application;

FIG. 6 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a third embodiment of the present application;

FIG. 7 is a schematic structural diagram of an optical system according to a fourth embodiment of the present application;

FIG. 8 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system according to a fourth embodiment of the present application;

FIG. 9 is a schematic view of an optical system according to a fifth embodiment of the present application;

FIG. 10 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fifth embodiment of the present application;

FIG. 11 is a schematic structural diagram of an optical system according to a sixth embodiment of the present application;

FIG. 12 shows a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a sixth embodiment of the present application;

FIG. 13 is a schematic view of a lens module according to an embodiment of the present application;

fig. 14 is a schematic diagram of an electronic device in an embodiment of the application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are for purposes of illustration only and do not denote a single embodiment.

Referring to fig. 1, in some embodiments of the present application, the optical system 100 includes, in order from an object side to an image side along an optical axis 110, 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. Specifically, the first lens element L1 includes an object-side surface S1 and an image-side surface S2, the second lens element L2 includes an object-side surface S3 and an image-side surface S4, the third lens element L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens element L4 includes an object-side surface S7 and an image-side surface S8, the fifth lens element L5 includes an object-side surface S9 and an image-side surface S10, the sixth lens element L6 includes an object-side surface S11 and an image-side surface S12, the seventh lens element L7 includes an object-side surface S13 and an image-side surface S14, and the eighth lens element L8 includes an object-side surface S15 and an image-side surface S16. The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are coaxially disposed, and an axis common to the lenses in the optical system 100 is an optical axis 110 of the optical system 100. In some embodiments, the optical system 100 further includes an imaging surface S19 located on the image side of the eighth lens L8, and the incident light can be imaged on the imaging surface S19 after being adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8.

The first lens element L1 has positive refractive power, and the object-side surface S1 of the first lens element L1 is convex at a position near the optical axis 110, which is beneficial to enhancing the convergence of the on-axis field rays, thereby being beneficial to shortening the total length of the optical system 100 and realizing the miniaturized design. The image-side surface S2 of the first lens element L1 is concave at the paraxial region 110, which is favorable for increasing the field angle of the optical system 100 and is favorable for reasonably deflecting the light rays with a large field of view, thereby being favorable for reducing the deflection angle born by each lens element at the image side of the first lens element L1, being favorable for balancing the deflection angle of the light rays on each lens element, and being favorable for improving the imaging quality of the optical system 100; in addition, the center thickness of the first lens L1 is reduced, and the thickness ratio of the first lens L1 is balanced, so that the design and molding of the first lens L1 are facilitated. The second lens element L2 with negative refractive power has a concave image-side surface S4 near the optical axis 110, which can match with the positive refractive power of the first lens element L1, and is favorable for balancing the spherical aberration generated by the first lens element L1, thereby improving the imaging quality of the optical system 100, and simultaneously being favorable for shortening the total length of the optical system 100 and further enlarging the field angle of the optical system 100. The third lens element L3 has negative refractive power, and the third lens element L3 is convex-concave at the paraxial region 110, which is favorable for smooth transition of light rays in the third lens element L3 and also favorable for reducing pupil aberration of the optical system 100, thereby being favorable for improving the imaging quality of the optical system 100. The fourth lens element L4 with positive or negative refractive power has a convex image-side surface S8 at a paraxial region 110, which is favorable for correcting aberrations such as distortion and field curvature of the optical system 100, thereby improving the imaging quality of the optical system 100. The fifth lens element L5 has positive refractive power or negative refractive power, and the image-side surface S10 of the fifth lens element L5 at a position near the optical axis 110 is a convex surface, which is beneficial to reasonably deflecting light rays at the fifth lens element L5, thereby being beneficial to reducing tolerance sensitivities of the lenses of the optical system 100 and further improving the production yield of the optical system 100. The sixth lens element L6 with negative refractive power has a convex-concave shape at the paraxial region 110, which is favorable for light beams to reasonably diverge toward the image side through the sixth lens element L6, so that astigmatism at the object side and the image side of the sixth lens element L6 can be favorably balanced, and thus the imaging quality of the optical system 100 can be improved, and aberration caused by curvature of the image plane S19 can be favorably reduced. The seventh lens element L7 with positive refractive power has a convex object-side surface S13 at a paraxial region 110, which is favorable for further enhancing the convergence of on-axis field rays and further shortening the overall length of the optical system 100. The image-side surface S14 of the seventh lens element L7 is concave at the paraxial region 110, which is beneficial for light to reasonably transit to the image plane S19 through the seventh lens element L7, so as to be beneficial for reducing the incident angle of the light to the image plane S19, and for correcting aberrations such as distortion of the optical system 100, thereby being beneficial for improving the imaging quality of the optical system 100. The eighth lens element L8 has negative refractive power, and the eighth lens element L8 is concave-convex at the paraxial region 110, which is beneficial to diverging the light beam to the imaging surface S19, thereby being beneficial to suppressing aberrations such as coma and astigmatism of the off-axis, and being beneficial to increasing the size of the imaging surface S19 of the optical system 100, thereby realizing large image plane characteristics, and being beneficial to better matching the incident angle of the light beam at the imaging surface S19 with the photosensitive element, and further being beneficial to improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 is provided with an aperture stop STO1, and the aperture stop STO1 may be disposed on the object side of the first lens L1 or between any two lenses, for example, the aperture stop STO1 is disposed on the object side of the first lens L1. In some embodiments, the optical system 100 is further provided with a stop STO2, and the stop STO2 may be provided between the second lens L2 and the third lens L3. In some embodiments, the optical system 100 further includes an infrared filter L9 disposed on the image side of the eighth lens L8. The ir filter L9 may be an ir cut filter, and is used for filtering out interference light and preventing the interference light from reaching the image plane S19 of the optical system 100 to affect normal imaging.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are both aspheric. The adoption of the aspheric surface structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, the object-side surface and the image-side surface of each lens of the optical system 100 may be spherical. It should be noted that the above embodiments are only examples of some embodiments of the present application, and in some embodiments, the surface of each lens in the optical system 100 may be an aspheric surface or any combination of spherical surfaces.

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. The lens made of plastic material can reduce the weight and production cost of the optical system 100, and the small size of the optical system 100 is matched to achieve the light and thin design of the optical system 100. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

It should be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, or the eighth lens L8 in some embodiments may be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or a non-cemented lens may be used.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: OAL/FNO of not less than 5mm and not more than 5.5mm; wherein OAL is a distance between the object-side surface S1 of the first lens L1 and the image-side surface S16 of the eighth lens L8 on the optical axis 110, and FNO is an f-number of the optical system 100. Specifically, OAL/FNO may be: 5.086, 5.112, 5.137, 5.189, 5.212, 5.236, 5.279, 5.303, 5.345 or 5.379, with values in mm. When the conditional expressions are satisfied, the optical system 100 can have a large aperture characteristic, so that the relative illumination of the imaging of the optical system 100 is improved, the imaging quality of the optical system 100 is further improved, and the optical system 100 can have good imaging quality at night, in rainy days and other low-light environments; meanwhile, the overall length of the optical system 100 is shortened, so that the structure of the optical system 100 is more compact, and the miniaturization design is realized. Having the above-described refractive power and surface profile characteristics and satisfying the above conditional expressions, the optical system 100 can achieve both good imaging quality and a miniaturized design.

In some embodiments, the optical system 100 satisfies the conditional expression: SD82/EPD is more than or equal to 1.0 and less than or equal to 1.3; SD82 is the maximum effective half-diameter of the image-side surface S16 of the eighth lens L8, and EPD is the entrance pupil diameter of the optical system 100. Specifically, the SD82/EPD may be: 1.133, 1.145, 1.168, 1.174, 1.196, 1.205, 1.224, 1.233, 1.240, or 1.242. When the above conditional expressions are satisfied, the size of the optical system 100 in the vertical axis direction can be configured reasonably, which is beneficial to shortening the size of the optical system 100, realizing miniaturization design, and simultaneously beneficial to enlarging the entrance pupil diameter of the optical system 100, thereby enlarging the aperture of the optical system 100, improving the relative illumination of the optical system 100, and further being beneficial to improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: CT8/R16 is more than or equal to 0.19 and less than or equal to 0.3; wherein, CT8 is the thickness of the eighth lens element L8 on the optical axis 110, and R16 is the curvature radius of the image-side surface S16 of the eighth lens element L8 on the optical axis 110. Specifically, CT8/R16 may be: 0.205, 0.209, 0.211, 0.215, 0.223, 0.229, 0.237, 0.245, 0.250, or 0.268. When the above conditional expressions are satisfied, the ratio of the center thickness of the eighth lens element L8 to the curvature radius of the image-side surface S16 can be configured reasonably, which is favorable for configuring the shape of the eighth lens element L8 reasonably, so that each position of the eighth lens element L8 has a suitable thickness ratio, which is favorable for designing and molding the eighth lens element L8, and is also favorable for shortening the total length of the optical system 100, thereby realizing a miniaturized design. Below the lower limit of the conditional expression, the central thickness of the eighth lens L8 is too small, which increases the difficulty in molding and assembling the eighth lens L8, increases the tolerance sensitivity of the eighth lens L8, and is not favorable for improving the imaging quality of the optical system 100. Exceeding the upper limit of the above conditional expression, the center thickness of the eighth lens L8 is too large, which is disadvantageous for reducing the overall length of the optical system 100, and makes it difficult to achieve a compact design.

In some embodiments, the optical system 100 satisfies the conditional expression: f3/f1 is more than or equal to-11 and less than or equal to-2; wherein f3 is the effective focal length of the third lens element L3, and f1 is the effective focal length of the first lens element L1. Specifically, f3/f1 may be: -4.185, -4.368, -4.984, -5.223, -5.567, -6.031, -6.257, -7.952, -8.205 or-9.613. When the above conditional expressions are satisfied, the refractive power distribution of the third lens element L3 and the first lens element L1 can be reasonably balanced, which is beneficial to the reasonable deflection of light at the third lens element L3 and the reduction of the deflection angle of light at the third lens element L3, thereby being beneficial to reducing the aberration sensitivity of the optical system 100, and simultaneously being beneficial to the negative refractive power of the third lens element L3 to effectively counteract the spherical aberration generated by the first lens element L1, thereby correcting the aberration of the optical system 100 to realize good imaging quality, and in addition, being beneficial to shortening the total length of the optical system 100, realizing the miniaturized design, increasing the field angle of the optical system 100, and satisfying the requirement of large-scale image capture.

In some embodiments, the optical system 100 satisfies the conditional expression: f2/f6 is more than or equal to1 and less than or equal to 2.5; where f2 is an effective focal length of the second lens L2, and f6 is an effective focal length of the sixth lens L6. Specifically, f2/f6 may be: 1.331, 1.358, 1.402, 1.467, 1.553, 1.639, 1.684, 1.725, 1.793, or 1.963. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the second lens element L2 and the sixth lens element L6 can be configured reasonably, so that the refractive powers of the second lens element L2 and the sixth lens element L6 are distributed reasonably, which is beneficial to improving aberrations such as spherical aberration of the optical system 100, and is further beneficial to improving the imaging quality of the optical system 100. Exceeding the upper limit of the conditional expression, the negative refractive power provided by the second lens element L2 is insufficient relative to the refractive power of the sixth lens element L6, which makes the spherical aberration correction of the optical system 100 difficult. Below the lower limit of the conditional expression, the negative refractive power of the second lens element L2 is too strong relative to the refractive power of the sixth lens element L6, which is likely to cause excessive aberration correction of the sixth lens element L6, and is not favorable for improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: -0.9mm ^-1 ≤R15/（f8*R16）≤-0.6mm ^-1 (ii) a Where f8 is an effective focal length of the eighth lens element L8, R15 is a radius of curvature of the object-side surface S15 of the eighth lens element L8 on the optical axis 110, and R16 is a radius of curvature of the image-side surface S16 of the eighth lens element L8 on the optical axis 110. In particular, R15/(f 8 × R16) may be: -0.638, -0.644, -0.653, -0.671, -0.684, -0.695, -0.722, -0.741, -0.753, or-0.762, the numerical units being mm ^-1 . When the above conditional expressions are satisfied, the effective focal length of the eighth lens element L8 and the relationship between the curvature radii of the object-side surface S15 and the image-side surface S16 of the eighth lens element L8 at the optical axis 110 can be reasonably configured, so that the eighth lens element L8 can reasonably diverge the light to the imaging surface S19, which is beneficial to reducing the incident angle of the light incident on the imaging surface S19, making the light easier to match with the photosensitive element to obtain good imaging quality, and simultaneously beneficial to improving astigmatism of the off-axis field of view, and improving the imaging quality of the optical system 100; in addition, the back focal length of the optical system 100 can be increased, so that the focusing yield of the optical system 100 at the module end can be improved.

In some embodiments, the optical system 100 satisfies the conditional expression: 2 is more than or equal to (CT 3+ CT4+ CT 5)/T56 is less than or equal to 8; wherein, CT3 is a thickness of the third lens element L3 on the optical axis 110, CT4 is a thickness of the fourth lens element L4 on the optical axis 110, CT5 is a thickness of the fifth lens element L5 on the optical axis 110, and T56 is a distance from the image-side surface S10 of the fifth lens element L5 to the object-side surface S11 of the sixth lens element L6 on the optical axis 110. Specifically, (CT 3+ CT4+ CT 5)/T56 may be: 2.586, 2.886, 3.024, 3.432, 3.697, 4.215, 4.647, 5.236, 5.741, or 6.972. When the above conditional expressions are satisfied, the central thicknesses of the third lens L3, the fourth lens L4, and the fifth lens L5 and the air interval between the fifth lens L5 and the sixth lens L6 can be reasonably configured, which is beneficial to shortening the total length of the optical system 100, realizing the miniaturization design, reducing the tolerance sensitivity of the optical system 100, and improving the molding yield of each lens and the assembly yield of the optical system 100. If the upper limit of the above conditional expression is exceeded, the air gap between the fifth lens L5 and the sixth lens L6 is too small, and the fifth lens L5 and the sixth lens L6 easily interfere with each other during assembly, which is disadvantageous in reducing tolerance sensitivity of the optical system 100. If the thickness distribution is less than the lower limit of the conditional expression, the thickness distribution of the third lens L3, the fourth lens L4 and the fifth lens L5 is not reasonable, which may result in an excessively thin central lens thickness and a reduction in the yield of lens molding.

In some embodiments, the optical system 100 satisfies the conditional expression: imgH/(10 × ct2) is not less than 1.8 and not more than 2.5; where ImgH is half of the image height corresponding to the maximum field angle of the optical system 100, and CT2 is the thickness of the second lens L2 on the optical axis 110. Specifically, imgH/(10 × ct2) may be: 1.807, 1.825, 1.844, 1.864, 1.873, 1.902, 1.941, 1.957, 1.963, or 1.974. When the above conditional expressions are satisfied, the half-image height of the optical system 100 and the center thickness of the second lens L2 can be reasonably configured, which is beneficial to the optical system 100 to realize large image plane characteristics and miniaturization design, thereby taking good imaging quality and miniaturization design into consideration, simultaneously being beneficial to improving the manufacturing and forming yield of the second lens L2, reducing the defect of poor forming of the second lens L2, being beneficial to the second lens L2 to effectively improve aberrations such as field curvature of the optical system 100, and improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: 0.8-2.0 of SAG61/SAG 71; where SAG61 is the rise of the object-side surface S11 of the sixth lens L6 at the maximum effective aperture, and SAG71 is the rise of the object-side surface S13 of the seventh lens L7 at the maximum effective aperture. Specifically, SAG61/SAG71 may be: 0.850, 0.963, 1.123, 1.265, 1.347, 1.445, 1.524, 1.698, 1.763 or 1.850. When the conditional expressions are satisfied, the rise of the object side of the sixth lens L6 and the rise of the object side of the seventh lens L7 can be reasonably configured, which is beneficial to reasonably configuring the shapes of the sixth lens L6 and the seventh lens L7, so that the sixth lens L6 and the seventh lens L7 have good processing manufacturability, thereby being beneficial to manufacturing and molding the sixth lens L6 and the seventh lens L7 and reducing the defect of poor molding; meanwhile, the light rays are favorably and reasonably deflected to the imaging surface S19 at the sixth lens L6 and the seventh lens L7, so that the incident angle of the main light rays incident to the imaging surface S19 is favorably reduced, further, the relative illumination of the imaging of the optical system 100 is favorably improved, in addition, the field curvature aberration generated by each lens at the object side of the sixth lens L6 is favorably and effectively corrected by the sixth lens L6 and the seventh lens L7, the field curvature of the optical system 100 is balanced, and further, the imaging quality of the optical system 100 is favorably improved.

In some embodiments, the optical system 100 satisfies the conditional expression: 4.4 is less than or equal to (R3 + R4)/(R3-R4) is less than or equal to 8; wherein, R3 is a curvature radius of the object-side surface S3 of the second lens element L2 at the optical axis 110, and R4 is a curvature radius of the image-side surface S4 of the second lens element L2 at the optical axis 110. Specifically, (R3 + R4)/(R3-R4) may be: 4.467, 4.694, 4.938, 5.614, 5.741, 6.258, 6.741, 6.993, 7.054, or 7.468. When the above conditional expressions are satisfied, the relationship between the curvature radii of the object-side surface S3 and the image-side surface S4 of the second lens L2 at the optical axis 110 can be reasonably configured, which is favorable for reasonably configuring the shape of the second lens L2, thereby reasonably allocating the optical deflection angle that the second lens L2 bears in the optical system 100, so that the light can be smoothly transited in the second lens L2, the aberration sensitivity of the optical system 100 is reduced, and simultaneously, the second lens L2 is also favorable for effectively improving the aberrations such as astigmatism of the off-axis field, and further favorable for improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f78/f is more than or equal to 1.2 and less than or equal to 1.7; where f78 is a combined focal length of the seventh lens L7 and the eighth lens L8, and f is an effective focal length of the optical system 100. Specifically, f78/f may be: 1.383, 1.392, 1.412, 1.438, 1.471, 1.493, 1.522, 1.535, 1.549 or 1.554. When the above conditional expressions are satisfied, the ratio of the combined focal length of the seventh lens element L7 and the eighth lens element L8 to the effective focal length of the optical system 100 can be reasonably configured, which is favorable for reasonably distributing the refractive power ratio of the seventh lens element L7 and the eighth lens element L8 in the optical system 100, thereby being favorable for restraining the on-axis spherical aberration generated by the optical system 100, and further improving the imaging quality of the on-axis view field of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: r11/f6 is more than or equal to-10 and less than or equal to-1; where R11 is a curvature radius of the object-side surface S11 of the sixth lens element L6 at the optical axis 110, and f6 is an effective focal length of the sixth lens element L6. Specifically, R11/f6 may be: -1.287, -1.841, -2.036, -2.328, -2.447, -2.639, -2.985, -5.314, -7.369 or-8.710. When the above conditional expressions are satisfied, the ratio of the curvature radius of the object-side surface S11 of the sixth lens L6 at the optical axis 110 to the effective focal length of the sixth lens L6 can be reasonably configured, which is beneficial for the sixth lens L6 to effectively correct aberrations such as field curvature of the optical system 100, thereby improving the imaging quality of the optical system 100, and simultaneously, is also beneficial for reasonably configuring the shape of the sixth lens L6, and improving the forming yield of the sixth lens L6. Below the lower limit of the conditional expression, the curvature radius of the object-side surface S11 of the sixth lens L6 is too small, which causes the surface shape of the sixth lens L6 to be excessively curved, and thus tends to reduce the molding yield of the sixth lens L6, making it difficult to manufacture the sixth lens L6. Exceeding the upper limit of the above conditional expression, the curvature radius of the object-side surface S11 of the sixth lens element L6 is not properly matched with the effective focal length of the sixth lens element L6, which results in an excessively large refractive power of the sixth lens element L6, and therefore the sixth lens element L6 is prone to overcorrection for aberration, which is not favorable for improving the imaging quality.

In some embodiments, the optical system 100 satisfies the conditional expression: imgH is more than or equal to 6mm; here, imgH is half the image height corresponding to the maximum field angle of the optical system 100. Specifically, imgH may be: 6.36, 6.42, 6.53, 6.66, 6.78, 6.85, 6.91, 7.02, 7.14 or 7.21, the numerical units being mm. When the above conditional expressions are satisfied, the optical system 100 can have a large image plane characteristic, so that a large-sized photosensitive element can be matched to obtain a high resolution, and good imaging quality can be achieved in accordance with a large aperture characteristic of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f/TTL is more than or equal to 0.7 and less than or equal to 0.9; where f is an effective focal length of the optical system 100, and TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane S19 of the optical system 100 on the optical axis 110, i.e., a total optical length of the optical system 100. Specifically, the f/TTL can be: 0.761, 0.765, 0.767, 0.772, 0.775, 0.779, 0.780, 0.783, 0.789 or 0.790. When the above conditional expressions are satisfied, the ratio of the effective focal length to the total optical length of the optical system 100 can be configured reasonably, which is beneficial to shortening the total optical length of the optical system 100, realizing miniaturization design, and simultaneously beneficial to balancing the long-focus characteristic and wide-angle characteristic of the system, thereby taking the long-range function and the large-range image capture effect into consideration. Below the lower limit of the above conditional expression, the effective focal length of the optical system is too short, and the field angle is too large, so that the aberration of the off-axis field of the optical system 100 is difficult to be effectively corrected, which is not favorable for improving the imaging quality; exceeding the upper limit of the above conditional expression, the effective focal length of the optical system 100 is too long, which is not favorable for shortening the total length of the optical system, and is not favorable for realizing the requirement of miniaturization design.

In some embodiments, the optical system 100 satisfies the conditional expression: f3/f2 is more than or equal to1 and less than or equal to 3; wherein f3 is the effective focal length of the third lens L3, and f2 is the effective focal length of the second lens L2. Specifically, f3/f2 may be: 1.339, 1.526, 1.741, 1.887, 2.023, 2.354, 2.663, 2.789, 2.882 or 2.999. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the third lens element L3 and the second lens element L2 can be configured reasonably, so that the refractive power distribution of the second lens element L2 and the third lens element L3 is balanced, which is beneficial to improving the spherical aberration of the optical system 100 and improving the imaging quality of the optical system 100. Above the upper limit of the conditional expression, the negative refractive power provided by the third lens element L3 is insufficient, which makes the spherical aberration correction of the optical system 100 difficult. Below the lower limit of the conditional expression, the negative refractive power of the third lens element L3 is too strong, which results in excessive aberration correction of the third lens element L3, and is not favorable for improving the imaging quality of the optical system 100.

It should be noted that in some embodiments, the optical system 100 may match a photosensitive element having a rectangular photosensitive surface, and the imaging surface S19 of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, the effective pixel region on the imaging surface S19 of the optical system 100 has a horizontal direction and a diagonal direction, the maximum angle of view FOV can be understood as the maximum angle of view in the diagonal direction of the optical system 100, and ImgH can be understood as a half of the length of the effective pixel region on the imaging surface S19 of the optical system 100 in the diagonal direction.

The reference wavelengths of the above effective focal length values are all 587.5618nm.

Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for detailed description. Although the embodiment of the present application has been described by taking eight lenses as an example, the number of lenses having refractive power in the optical system 100 is not limited to eight, and the optical system 100 may include other numbers of lenses. It will be understood by those skilled in the art that the number of lenses constituting the optical system may be varied to achieve the various results and advantages described in the present specification without departing from the technical solutions claimed in the present application.

First embodiment

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of an optical system 100 in the first embodiment, in which the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, in which the reference wavelength of the astigmatism diagram and the distortion diagram is 587.5618nm, from left to right, and the other embodiments are the same.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is concave at the paraxial region 110; the object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110; the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is concave at the paraxial region 110; the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 110, and the image-side surface S8 is convex at the paraxial region 110; the object-side surface S9 of the fifth lens element L5 is convex at the paraxial region 110, and the image-side surface S10 is convex at the paraxial region 110; the object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 110, and the image-side surface S12 is concave at the paraxial region 110; the object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 110, and the image-side surface S14 is concave at the paraxial region 110; the object-side surface S15 of the eighth lens element L8 is convex at the paraxial region 110, and the image-side surface S16 is concave at the paraxial region 110.

The object-side surface and the image-side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are aspheric, and the same applies to other embodiments.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are all made of plastic, and the same applies to other embodiments.

In addition, the parameters of the optical system 100 are given in table 1. In which elements from the object plane (not shown) to the image plane S19 are sequentially arranged in the order of elements from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface at the optical axis 110 for the corresponding surface number. The surface number S1 and the surface number S2 are the object-side surface S1 and the image-side surface S2 of the first lens L1, respectively, that is, in the same lens, the surface with the smaller surface number is the object-side surface, and the surface with the larger surface number is the image-side surface. The first value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110.

It should be noted that in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared filter L9, but the distance from the image side surface S16 of the eighth lens L8 to the image plane S19 is kept constant. In the first embodiment, the effective focal length f =7.03mm, the total optical length TTL =9.16mm, half of the maximum field angle HFOV =41.78deg, and the f-number FNO =1.5 of the optical system 100. And the reference wavelengths of the focal length, the refractive index and the Abbe number of each lens are 587.5618nm, and the same is true for other embodiments.

TABLE 1

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given by table 2. The surface numbers S1 to S16 represent image side surfaces or object side surfaces S1 to S16, respectively. And K-a30 from top to bottom respectively indicate the types of aspheric coefficients, where K indicates a conic coefficient, A4 indicates a fourth-order aspheric coefficient, A6 indicates a sixth-order aspheric coefficient, A8 indicates an eighth-order aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

where Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric surface vertex, K is the conic coefficient, and Ai is the coefficient corresponding to the higher-order term in the aspheric surface profile formula.

TABLE 2

In addition, fig. 2 includes a Longitudinal Spherical Aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, where the Longitudinal Spherical Aberration curve represents the convergent focus deviation of light rays with different wavelengths after passing through the lens, where the ordinate represents Normalized Pupil coordinates (Normalized Pupil Coordinator) from the Pupil center to the Pupil edge, and the abscissa represents focus deviation, i.e., the distance (in mm) from the image plane S19 to the intersection of the light rays and the optical axis 110. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with different wavelengths in the first embodiment tend to be consistent, and the diffuse speckles or color halos in the imaging picture are effectively inhibited. Fig. 2 also includes an astigmatism graph (ASTIGMATIC FIELD CURVES) of the optical system 100, in which the abscissa represents the focus offset, the ordinate represents the image height in mm, and the S-curve in the astigmatism graph represents the sagittal curvature at 587.5618nm and the T-curve represents the meridional curvature at 587.5618nm. As can be seen from the figure, the field curvature of the optical system 100 is small, the field curvature and astigmatism of each field are well corrected, and the center and the edge of each field have clear images. Fig. 2 further includes a DISTORTION plot (distorrion) of the optical system 100, the DISTORTION plot representing DISTORTION magnitude values corresponding to different angles of view, wherein the abscissa represents the DISTORTION value in mm, and the ordinate represents the image height in mm. As can be seen from the figure, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

Second embodiment

Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of the optical system 100 in the second embodiment, in which the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 4 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, which is shown from left to right.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is concave at the paraxial region 110; the object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110; the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is concave at the paraxial region 110; the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 110, and the image-side surface S8 is convex at the paraxial region 110; the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is convex at the paraxial region 110; the object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 110, and the image-side surface S12 is concave at the paraxial region 110; the object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 110, and the image-side surface S14 is concave at the paraxial region 110; the object-side surface S15 of the eighth lens element L8 is convex at the paraxial region 110, and the image-side surface S16 is concave at the paraxial region 110.

In addition, the parameters of the optical system 100 are given in table 3, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 3

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 4, and the definitions of the parameters can be derived from the first embodiment, which is not repeated herein.

TABLE 4

In addition, as can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of the optical system 100 in the third embodiment, in which the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with negative refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

In addition, the parameters of the optical system 100 are given in table 5, and the definitions of the parameters can be derived from the first embodiment, which is not repeated herein.

TABLE 5

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 6, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 6

In addition, as can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, fig. 7 is a schematic structural diagram of the optical system 100 in the fourth embodiment, in which the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 8 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment from left to right.

In addition, the parameters of the optical system 100 are given in table 7, and the definitions of the parameters can be derived from the first embodiment, which is not repeated herein.

TABLE 7

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 8, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 8

In addition, as can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, fig. 9 is a schematic structural diagram of the optical system 100 in the fifth embodiment, in which the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

In addition, the parameters of the optical system 100 are shown in table 9, and the definitions of the parameters can be derived from the first embodiment, which is not repeated herein.

TABLE 9

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 10, and the definition of each parameter can be obtained from the first embodiment, which is not repeated herein.

Watch 10

In addition, as can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Sixth embodiment

Referring to fig. 11 and 12, fig. 11 is a schematic structural diagram of the optical system 100 in the sixth embodiment, and the optical system 100 includes, in order from an object side to an image side, an aperture stop STO1, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a stop STO2, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 12 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the sixth embodiment in order from left to right.

In addition, the parameters of the optical system 100 are shown in table 11, and the definitions of the parameters can be obtained from the first embodiment, which are not repeated herein.

TABLE 11

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 12, and definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 12

In addition, as can be seen from the aberration diagram in fig. 12, the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

The examples of the present application also satisfy the data of table 13 below, and the effects obtainable by satisfying the following data can be inferred from the above descriptions.

Watch 13

Referring to fig. 13, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form the lens module 200. At this time, the light-sensing surface of the light-sensing element 210 coincides with the image-forming surface S19 of the optical system 100. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. The optical system 100 is adopted in the lens module 200, so that the size of the lens module 200 is reduced, and the lens module 200 has large aperture and large image plane characteristics, thereby achieving both good imaging quality and miniaturization design.

Referring to fig. 13 and 14, in some embodiments, the lens module 200 can be applied to an electronic device 300, the electronic device 300 includes a housing 310, and the lens module 200 is disposed in the housing 310. Specifically, the electronic apparatus 300 may be, but is not limited to, a wearable device such as a smart watch or an onboard image capturing apparatus such as a cellular phone, a video phone, a smart phone, an electronic book reader, and a vehicle data recorder. When the electronic device 300 is a smartphone, the housing 310 may be a middle frame of the electronic device 300. By adopting the lens module 200 in the electronic device 300, the electronic device 300 can have a large aperture and a large image plane characteristic while the size of the electronic device 300 is reduced, thereby achieving both good imaging quality and a miniaturized design.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. An optical system, comprising eight lens elements with refractive power, in order from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

a second lens element with negative refractive power having a concave image-side surface at paraxial region;

a third lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

a fourth lens element with refractive power having a convex image-side surface at paraxial region;

a fifth lens element with refractive power having a convex image-side surface at a paraxial region;

a sixth lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

a seventh lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

an eighth lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

and the optical system satisfies the following conditional expression:

5mm≤OAL/FNO≤5.5mm；

-11≤f3/f1≤-2；

wherein OAL is a distance on an optical axis from an object-side surface of the first lens element to an image-side surface of the eighth lens element, FNO is an f-number of the optical system, f3 is an effective focal length of the third lens element, and f1 is an effective focal length of the first lens element.

2. The optical system according to claim 1, characterized in that the following conditional expression is satisfied:

1.0≤SD82/EPD≤1.3；

wherein SD82 is the maximum effective half aperture of the image side surface of the eighth lens, and EPD is the entrance pupil diameter of the optical system.

3. The optical system according to claim 1, characterized in that the following conditional expression is satisfied:

CT8/R16 is more than or equal to 0.19 and less than or equal to 0.3; and/or the presence of a gas in the atmosphere,

2 is more than or equal to (CT 3+ CT4+ CT 5)/T56 is less than or equal to 8; and/or the presence of a gas in the atmosphere,

1.8≤ImgH/（10*CT2）≤2.5；

wherein CT8 is a thickness of the eighth lens element on an optical axis, R16 is a curvature radius of an image-side surface of the eighth lens element on the optical axis, CT3 is a thickness of the third lens element on the optical axis, CT4 is a thickness of the fourth lens element on the optical axis, CT5 is a thickness of the fifth lens element on the optical axis, T56 is a distance between the image-side surface of the fifth lens element and an object-side surface of the sixth lens element on the optical axis, imgH is a half of an image height corresponding to a maximum field angle of the optical system, and CT2 is a thickness of the second lens element on the optical axis.

4. The optical system according to claim 1, characterized in that the following conditional expression is satisfied:

1≤f2/f6≤2.5；

wherein f2 is an effective focal length of the second lens, and f6 is an effective focal length of the sixth lens.

5. The optical system according to claim 1, characterized in that the following conditional expression is satisfied:

-0.9mm ^-1 ≤R15/（f8*R16）≤-0.6mm ^-1 ；

wherein f8 is an effective focal length of the eighth lens element, R15 is a curvature radius of an object-side surface of the eighth lens element on an optical axis, and R16 is a curvature radius of an image-side surface of the eighth lens element on the optical axis.

6. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.8≤SAG61/SAG71≤2.0；

SAG61 is the saggital height of the object side surface of the sixth lens at the maximum effective aperture, and SAG71 is the saggital height of the object side surface of the seventh lens at the maximum effective aperture.

7. The optical system according to claim 1, wherein the following conditional expression is satisfied:

4.4 is less than or equal to (R3 + R4)/(R3-R4) is less than or equal to 8; and/or the presence of a gas in the atmosphere,

-10≤R11/f6≤-1；

wherein R3 is a curvature radius of an object-side surface of the second lens element at the optical axis, R4 is a curvature radius of an image-side surface of the second lens element at the optical axis, R11 is a curvature radius of an object-side surface of the sixth lens element at the optical axis, and f6 is an effective focal length of the sixth lens element.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.2≤f78/f≤1.7；

wherein f78 is a combined focal length of the seventh lens and the eighth lens, and f is an effective focal length of the optical system.

9. A lens module comprising a photosensitive element and the optical system of any one of claims 1 to 8, wherein the photosensitive element is disposed on an image side of the optical system.

10. An electronic device comprising a housing and the lens module of claim 9, wherein the lens module is disposed on the housing.