Patent Publication Number: US-2022214521-A1

Title: Optical system, camera module, and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage, filed under 35 U.S.C. § 371, of International Patent Application No. PCT/CN2020/079517, entitled “OPTICAL SYSTEM, CAMERA MODULE, AND ELECTRONIC DEVICE”, filed on 16 Mar. 2020, the contents of which are incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to relates to a camera field, in particular to an optical system, a camera module, and an electronic device. 
     BACKGROUND 
     In recent years, as camera lenses are applied to portable electronics such as smart phones, the performance of the camera lens also changes greatly with the increase of the user&#39;s demand for capturing quality. Theoretically, by configuring a plurality of lenses, a system can have more space and freedom to adjust an incident light path. This is one of the most efficient ways to improve the imaging quality of an optical system. However, how to well configure the performance of each of the lenses in the optical system to ensure the high capturing quality of the system is one of the main concerns of the current lens design. 
     SUMMARY 
     According to embodiments of the present disclosure, an optical system is provided. 
     An optical system includes, successively in order from an object side to an image side: 
     a first lens having a refractive power, an object side surface of the first lens being concave at a paraxial area thereof, and an image side surface of the first lens being convex at the paraxial area thereof; 
     a second lens having a positive refractive power, an object side surface of the second lens being convex at a paraxial area thereof, and an image side surface of the second lens being concave at the paraxial area thereof; 
     a third lens having a positive refractive power, and an image side surface of the third lens being convex at a paraxial area thereof; 
     a fourth lens having a negative refractive power, and an object side surface of the fourth lens being concave at a paraxial area thereof; 
     a fifth lens having a refractive power; 
     a sixth lens having a negative refractive power, and an object side surface of the sixth lens being concave at a paraxial area thereof; 
     a seventh lens having a positive refractive power, and an object side surface of the seventh lens being convex at a paraxial area thereof; and 
     an eighth lens having a negative refractive power, an object side surface of the eighth lens being convex at a paraxial area thereof, and an image side surface of the eighth lens being concave at the paraxial area thereof. 
     A camera module includes a photosensitive element and the optical system as described above. The photosensitive element is arranged on an image side of the optical system. 
     An electronic device includes a fixing member and the camera module as described above. The camera module is provided on the fixing member. 
     Details of one or more embodiments of the present disclosure will be given in the following description and attached drawings. Other features, objects and advantages of the present disclosure will become apparent from the description, drawings, and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to better describe and illustrate the embodiments and/or examples of the contents disclosed herein, reference may be made to one or more drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed contents, the currently described embodiments and/or examples, and the best mode of these contents currently understood. 
         FIG. 1  is a schematic view of an optical system according to a first embodiment of the present disclosure. 
         FIG. 2  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the first embodiment. 
         FIG. 3  is a schematic view of an optical system according to a second embodiment of the present disclosure. 
         FIG. 4  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the second embodiment. 
         FIG. 5  is a schematic view of an optical system according to a third embodiment of the present disclosure. 
         FIG. 6  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the third embodiment. 
         FIG. 7  is a schematic view of an optical system according to a fourth embodiment of the present disclosure. 
         FIG. 8  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the fourth embodiment. 
         FIG. 9  is a schematic view of an optical system according to a fifth embodiment of the present disclosure. 
         FIG. 10  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the fifth embodiment. 
         FIG. 11  is a schematic view of an optical system according to a sixth embodiment of the present disclosure. 
         FIG. 12  is a graph showing longitudinal spherical aberration (mm), astigmatism (mm), and distortion (%) of the optical system according to the sixth embodiment. 
         FIG. 13  is a schematic view of a camera module according to an embodiment of the present disclosure. 
         FIG. 14  is a schematic view of an electronic device according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. Preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thorough and comprehensive. 
     Referring to  FIG. 1 , in some embodiments of the present disclosure, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1 , a second lens L 2 , a stop STO, a third lens L 3 , a fourth lens L 4 , a fifth lens L 5 , a sixth lens L 6 , a seventh lens L 7 , and an eighth lens L 8 . The first lens L 1  has a positive refractive power or a negative refractive power. The second lens L 2  has a positive refractive power. The third lens L 3  has a positive refractive power. The fourth lens L 4  has a negative refractive power. The fifth lens L 5  has a positive refractive power or a negative refractive power. The sixth lens L 6  has a negative refractive power. The seventh lens L 7  has a positive refractive power. The eighth lens L 8  has a negative refractive power. The first lens L 1  to the eighth lens L 8  each contain only one lens, and the lenses in the optical system  10  are arranged coaxially with the stop STO. That is, an optical axis of each of the lenses and a center of the stop STO are on the same straight line. This straight line may be referred to as an optical axis of the optical system  10 . 
     The first lens L 1  includes an object side surface S 1  and an image side surface S 2 . The second lens L 2  includes an object side surface S 3  and an image side surface S 4 . The third lens L 3  includes an object side surface S 5  and an image side surface S 6 . The fourth lens L 4  includes an object side surface S 7  and an image side surface S 8 . The fifth lens L 5  includes an object side surface S 9  and an image side surface S 10 . The sixth lens includes an object side surface S  11  and an image side surface S 12 . The seventh lens includes an object side surface S 13  and an image side surface S 14 . The eighth lens includes an object side surface S 15  and an image side surface S 16 . In addition, the optical system  10  further has an imaging surface S 19 , which is located on an image side of the eighth lens. Generally, the imaging surface S 19  of the optical system  10  overlaps a photosensitive surface of a photosensitive element. For ease of understanding, the imaging surface S 19  can be regarded as the photosensitive surface of the photosensitive element. 
     In the above embodiment, the object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and the image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. The object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and the image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The image side surface S 6  of the third lens L 3  is convex at a paraxial area thereof. The object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof. The object side surface S 11  of the sixth lens is concave at a paraxial area thereof. The object side surface S 13  of the seventh lens is convex at a paraxial area thereof. The object side surface S 15  of the eighth lens is convex at a paraxial area thereof, and the image side surface S 16  of the eighth lens is concave at the paraxial area thereof. 
     In the above optical system  10 , the second lens L 2  have the positive refractive power, such that an ability of the system to correct aberrations can be effectively improved, and the sensitivity of the system can be reduced. By designing the object side surface S 3  of the second lens L 2  to be convex, the second lens L 2  can bear more positive refractive power, and can effectively reduce the aberration of the entire system, reduce the sensitivity of the system, and improve the yield of the system, which is also beneficial to the subsequent processing and assembly of the structures. The image side surface S 6  of the third lens L 3  is designed to be convex, which can effectively cooperate with the first lens L 1  and the second lens L 2  to reduce the spherical aberration of the system and improve the aberration correction ability of the system. The object side surface S 13  of the seventh lens L 7  is designed to be convex, such that the seventh lens L 7  can bear a reasonable positive refractive power to share part of the refractive power of the system, thus avoiding excessive concentration of the positive refractive power on the second lens L 2  and the third lens L 3 . In addition, this can further cooperate with the negative refractive power of the fourth lens L 4  and the positive refractive power of the seventh lens L 7 , which can facilitate the distribution of the refractive power of the entire system, avoid excessive concentration of refractive power, and further help balance the vertical chromatic aberration and lateral chromatic aberration of the system. By well configuring the refractive power and the surface shape relationship between the lenses, the above optical system  10  can have excellent capturing quality. 
     In the above embodiments, the object side surfaces and the image side surfaces of the first lens L 1  to the eighth lens L 8  are both aspherical, and the object side surface S 15  and the image side surface S 16  of the eighth lens L 8  both have inflection points. The aspheric surface configuration can further help the optical system  10  to eliminate aberrations and solve the problem of distortion of the field of view. In addition, it is also beneficial to the miniaturized design of the optical system  10 , such that the optical system  10  can have excellent optical effect while maintaining the miniaturized design. Of course, in other embodiments, the object side surface of any one of the first lens L 1  to the eighth lens L 8  can be spherical or aspherical, the image side surface of any one of the first lens L 1  to the eighth lens L 8  can be spherical or aspherical. Through the cooperation of the spherical surface and the aspheric surface, the aberration problem can also be effectively eliminated, such that the optical system  10  has an excellent imaging effect, while improving the flexibility of design and assembly of the lenses. In particular, when the eighth lens L 8  is an aspherical lens, it is beneficial to finally correct the aberrations generated by the front lenses, such that it is beneficial to improve the imaging quality. It should be noted that the shape of the spherical or aspheric surface is not limited to the shape of the spherical or aspheric surface shown in the drawings. The drawings are for reference only and are not drawn strictly to scale. 
     The surface shape of the aspheric surface can be calculated by referring to the following aspheric formula: 
     
       
         
           
             Z 
             = 
             
               
                 
                   cr 
                   2 
                 
                 
                   1 
                   + 
                   
                     
                       1 
                       - 
                       
                         
                           ( 
                           
                             k 
                             + 
                             1 
                           
                           ) 
                         
                         ⁢ 
                         
                           c 
                           2 
                         
                         ⁢ 
                         
                           r 
                           2 
                         
                       
                     
                   
                 
               
               + 
               
                 
                   ∑ 
                   i 
                 
                 ⁢ 
                 
                   Ai 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     r 
                     i 
                   
                 
               
             
           
         
       
     
     where, Z is a distance from a corresponding point on an aspheric surface to a plane tangent to a vertex of the surface, r is a distance from a corresponding point on the aspheric surface to the optical axis, c is a curvature of the vertex of the aspheric surface, k is a conic coefficient, and Ai is a coefficient corresponding to the i th  high-order term in the aspheric surface shape formula. 
     In another aspect, when the object side surface or image side surface of a certain lens is aspherical, such surface can be overall convex or overall concave. Alternatively, such surface can also be designed to have a structure with inflection points. As such, the shape of the surface will change from its center to its edge. For example, the surface is convex at its center and is concave at its edge. It should be noted that when describing that a side surface of the lens at the optical axis (a central area of the side surface) is convex in an embodiment of the present disclosure, it can be understood that an area of this side surface of the lens at its paraxial area is convex. Therefore, it can also be determined that the side surface is convex at its paraxial area. When describing a side surface of the lens is concave at its circumference, it can be understood that an area of the side surface is concave when approaching the maximum effective radius. For example, when the side surface is convex at its paraxial area and is also convex at its circumference, a shape of the side surface in a direction from its center (the optical axis) to its edge may be completely convex, or may be first convex at its center and be then transitioned to be concave, and then become convex when approaching the maximum effective radius. These are only examples to illustrate various shapes and structures (concave-convex conditions) of the side surface at the optical axis and the circumference, and the various shapes and structures (concave-convex conditions) of the side surface are not fully described, but other situations can be derived from the above examples, and should be considered as contents disclosed in the present disclosure. 
     In the above embodiments, each of the lenses in the optical system  10  is made of plastic. Of course, in some embodiments, each of the lenses in the optical system  10  is made of glass. The lens made of plastic can reduce the weight of the optical system  10  and the manufacturing cost, while the lens made of glass can withstand higher temperatures and have excellent optical effects. In other embodiments, the first lens L 1  is made of glass, and the second lens L 2  to the eighth lens L 8  are all made of plastic. In this case, since the lenses located on an object side in the optical system  10  are made of glass, the glass-made lenses located on the object side have a good resistance to extreme environments and are not susceptible to aging due to the impact of the environment on the object side. Therefore, when the optical system  10  is under the extreme environments such as exposed to the sun or in high temperature environment, this structure can effectively balance between the optical performance and cost of the system. Of course, the material configuration of the lenses in the optical system  10  is not limited to the above embodiments, and any lens may be made of plastic or glass. 
     In some embodiments, the optical system  10  includes an infrared cut-off filter L 9 . The infrared cut-off filter L 9  is arranged on an image side of the eighth lens L 8 , and is fixedly arranged relative to each of the lenses in the optical system  10 . The infrared cut-off filter L 9  includes an object side surface S 17  and an image side surface S 18 . The infrared cut-off filter L 9  is used to filter out infrared light and prevent infrared light from reaching the imaging surface S 19  of the system, thereby preventing the infrared light from interfering with normal imaging. The infrared cut-off filter L 9  can be assembled with the lenses as a part of the optical system  10 . In other embodiments, the infrared cut-off filter L 9  is not a component of the optical system  10 . In this case, when the optical system  10  and the photosensitive element are assembled into a camera module, the infrared cut-off filter L 9  can be mounted between the optical system  10  and the photosensitive element. In some embodiments, the infrared cut-off filter L 9  may also be arranged on the object side of the first lens L 1 . In addition, in some embodiments, the infrared cut-off filter L 9  may be omitted, while a filter coating is provided on any one of the first lens L 1  to the eighth lens L 8  to achieve the effect of filtering the infrared light. 
     In other embodiments, the first lens L 1  may also include two or more lenses. An object side surface of a lens closest to the object side is the object side surface S 1  of the first lens L 1 , and an image side surface of a lens closest to the image side is the image side surface S 2  of the first lens L 1 . Correspondingly, any one of the second lens L 2 , the third lens L 3 , the fourth lens L 4 , the fifth lens L 5 , the sixth lens L 6 , the seventh lens L 7 , and the eighth lens L 8  in some embodiments is not limited to only include one lens. 
     In some embodiments, the optical system  10  further satisfies the following conditions: 
     TTL/Imgh&lt;1.36; where TTL is a distance from the object side surface S 1  of the first lens L 1  to the imaging surface S 19  of the optical system  10  on the optical axis, and Imgh is half of a diagonal length of an effective imaging area of the optical system  10  on the imaging surface S 19 . In some embodiments, the TTL/Imgh is equal to 1.290, 1.292, 1.295, 1.297, 1.299, or 1.30. When the above condition is satisfied, the optical system  10  can achieve a miniaturized design. 
     2&lt;f/R16&lt;4; where f is an effective focal length of the optical system  10 , and R16 is a radius of curvature of the image side surface S 16  of the eighth lens L 8  at the optical axis. In some embodiments, the f/R16 is equal to 3.75, 3.78, 3.80, 3.82, 3.85, 3.87, or 3.89. When the above condition is satisfied, the effective focal length of the optical system  10  and the radius of curvature of the image side surface S 16  of the eighth lens L 8  can be reasonably configured, which is beneficial to reduce the main light angle on the imaging surface S 19  of the system and improve the photosensitive efficiency of the photosensitive element when being assembled. 
     FNO≤2; where FNO is an f-number of the optical system  10 . In some embodiments, the FNO is equal to 1.80, 1.82, 1.84, 1.86, or 1.88. When the above condition is satisfied, the optical system  10  has a large-aperture characteristic, so that the amount of incident light can be increased, the captured image is clearer, and the high-quality capturing of night scenes, starry sky and other scenes with low brightness can be achieved. 
     1&lt;SD12/SD21&lt;1.4; where SD12 is the maximum effective semiaperture of the image side surface S 2  of the first lens L 1 , SD21 is the maximum effective semiaperture of the object side surface S 3  of the second lens L 2 . In some embodiments, the SD12/SD21 is equal to 1.280, 1.283, 1.287, 1.290, 1.292, 1.295, 1.300, 1.305. When the above condition is satisfied, a size of the front end of the optical system  10  can be effectively reduced. 
     TTL/f&lt;1.65; where TTL is the distance from the object side surface S 1  of the first lens L 1  to the imaging surface S 19  of the optical system  10  on the optical axis, and f is the effective focal length of the optical system  10 . In some embodiments, the TTL/f is equal to 1.58, 1.59, 1.60, or 1.61. When the above condition is satisfied, the optical system  10  can meet the requirements of the miniaturized design. 
     tan(HFOV)&gt;1.09; where HFOV is half of the maximum angle of field of view of the optical system  10 . In some embodiments, the tan(HFOV) is equal to 1.242, 1.244, 1.245, 1.247, or 1.249. When the above condition is satisfied, the optical system  10  can achieve a small wide-angle characteristic. 
     0&lt;T23/CT3&lt;0.9; where T23 is a distance from the image side surface S 4  of the second lens L 2  to the object side surface S 5  of the third lens L 3  on the optical axis, and CT3 is a thickness of the third lens L 3  on the optical axis. In some embodiments, the T23/CT3 is equal to 0.803, 0.806, 0.810, 0.812, 0.815, or 0.818. When the above condition is satisfied, it is beneficial to reduce the deflection angle of the light in the system, thereby effectively reducing the sensitivity of the system. 
     Hereafter, the optical system  10  of the present disclosure will be described in more specific and detailed embodiments. 
     First Embodiment 
     Referring to  FIGS. 1 and 2 , in the first embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a negative refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the first embodiment is included in  FIG. 2 . The reference wavelength for astigmatism diagram and distortion diagram is 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is convex at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is convex at the paraxial area thereof. The object side surface S 7  is convex at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is concave at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is convex at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is convex at a circumference thereof, and the image side surface S 12  is concave at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is convex at the paraxial area thereof. The object side surface S 13  is convex at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is concave at a circumference thereof, and the image side surface S 16  is convex at the circumference thereof. 
     In the above optical system  10 , the second lens L 2  has the positive refractive power, such that the ability of the system to correct aberrations can be effectively improved, and the sensitivity of the system can be reduced. By designing the object side surface S 3  of the second lens L 2  to be convex, the second lens L 2  can bear more positive refractive power, and can effectively reduce the aberration of the entire system, reduce the sensitivity of the system, and improve the yield of the system, which is also beneficial to the subsequent processing and assembly of the structures. The image side surface S 6  of the third lens L 3  is designed to be convex, which can effectively cooperate with the first lens L 1  and the second lens L 2  to reduce the spherical aberration of the system and improve the aberration correction ability of the system. The object side surface S 13  of the seventh lens L 7  is designed to be convex, such that the seventh lens L 7  can bear a reasonable positive refractive power to share part of the refractive power of the system, avoiding excessive concentration of the positive refractive power on the second lens L 2  and the third lens L 3 . In addition, this can further cooperate with the negative refractive power of the fourth lens L 4  and the positive refractive power of the seventh lens L 7 , which will facilitate the distribution of the refractive power of the entire system, avoid excessive concentration of refractive power, and further help balance the vertical chromatic aberration and lateral chromatic aberration of the system. The above optical system  10  can have excellent capturing quality by well configuring the refractive power and the surface shape relationship between the lenses. 
     The object side surfaces and the image side surfaces of the first lens L 1  to the eighth lens L 8  are both aspherical, and the object side surface S 15  and the image side surface S 16  of the eighth lens L 8  both have inflection points. By cooperating the aspheric surface shapes of each of the lenses in the optical system  10 , the problem of distortion of the field of view of the optical system  10  can be effectively solved, and the lens can achieve excellent optical effects even when the lenses are small and thin. Therefore, the optical system  10  can have a smaller volume, which is beneficial to the miniaturized design of the optical system  10 . 
     Each of the lenses in the optical system  10  is made of plastic. The use of the lenses made of plastic can reduce the manufacturing cost of the optical system  10 . 
     In the first embodiment, the optical system  10  satisfies the following conditions: 
     TTL/Imgh= 1 . 29 ; where TTL is a distance from the object side surface S 1  of the first lens L 1  to the imaging surface S 19  of the optical system  10  on the optical axis, and Imgh is half of a diagonal length of an effective imaging area of the optical system  10  on the imaging surface S 19 . When the above condition is satisfied, the optical system  10  can achieve a miniaturized design. 
     f/R16=3.89; where f is an effective focal length of the optical system  10 , and R16 is a radius of curvature of the image side surface S 16  of the eighth lens L 8  at the optical axis. When the above condition is satisfied, the effective focal length of the optical system  10  and the radius of curvature of the image side surface S 16  of the eighth lens L 8  can be reasonably configured, which is beneficial to reduce the main light angle on the imaging surface S 19  of the system and improve photosensitive efficiency of a photosensitive element when being assembled. 
     FNO=1.85; where FNO is an f-number of the optical system  10 . When the above condition is satisfied, the optical system  10  has a large-aperture characteristic, so that the amount of incident light can be increased, the captured image is clearer, and the high-quality capturing of night scenes, starry sky and other scenes with low brightness can be achieved. 
     SD12/SD21=1.287; where SD12 is the maximum effective semiaperture of the image side surface S 2  of the first lens L 1 , SD21 is the maximum effective semiaperture of the object side surface S 3  of the second lens L 2 . When the above condition is satisfied, a size of the front end of the optical system  10  can be effectively reduced. 
     TTL/f=1.59; where TTL is the distance from the object side surface S 1  of the first lens L 1  to the imaging surface S 19  of the optical system  10  on the optical axis, and f is the effective focal length of the optical system  10 . When the above condition is satisfied, the optical system  10  can meet the requirements of a miniaturized design. 
     tan(HFOV)=1.25; where HFOV is half of the maximum angle of field of view of the optical system  10 . When the above condition is satisfied, the optical system  10  can achieve a small wide-angle characteristic. 
     T23/CT3=0.81; where T23 is a distance from the image side surface S 4  of the second lens L 2  to the object side surface S 5  of the third lens L 3  on the optical axis, and CT3 is a thickness of the third lens L 3  on the optical axis. When the above condition is satisfied, it is beneficial to reduce the deflection angle of the light in the system, thereby effectively reducing the sensitivity of the system. 
     In addition, parameters of the lenses of the optical system  10  are shown in Table 1 and Table 2. Table 2 shows aspheric coefficients of the lenses in Table 1. In table 2, k is a conic coefficient, and Ai is a coefficient corresponding to the i th  high-order term in the aspheric surface shape formula. The elements from the object surface to the image surface (the imaging surface  19 , which can also be understood as a photosensitive surface of the photosensitive element when assembling in later) are arranged in the order of the elements in Table 1 from top to bottom. A subject located on the object surface can be clearly imaged on the imaging surface  19  of the optical system  10 . The surface numbers 1 and 2 indicate the object side surface S 1  and the image side surface S 2  of the first lens L 1 , 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 Y radius in Table 1 is the radius of curvature of the object side surface or image side surface indicated by corresponding surface number on the optical axis. In the “thickness” parameter column of a lens, the first value is the thickness of the lens on the optical axis, and the second value is a distance from the image side surface of the lens to the object side surface of the latter lens on the optical axis. The optical axis of each of the lenses are on the same straight line. This straight line may be referred to as the optical axis of the optical system  10 . It should be noted that in the following embodiments, an infrared cut-off filter L 9  may be or may be not an element in the optical system  10 . 
     In the first embodiment, the effective focal length of the optical system  10  is indicated by f, and f=4.38 mm. The f-number is indicated by FNO, and FNO=1.85. The maximum angle of field of view (that is, a diagonal angle of field of view) is indicated by FOV, and FOV=102.9°. The total optical length is indicated by TTL, and TTL=6.95 mm. 
     In addition, in the following embodiments (the first embodiment to a sixth embodiment), the reference wavelength for the refractive index, the abbe number, and the focal lengths of each lens is 555 nm. In addition, the calculation of the conditions, and the structures of the lenses in each embodiment are based on the parameters of the lenses (such as parameters in Table 1, Table 2, Table 3, Table 4, etc.). 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 First Embodiment 
               
               
                 f = 4.38 mm, FNO = 1.85, FOV = 102.9°, TTL = 6.95 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −3.5729 
                 0.4333 
                 Plastic 
                 1.54 
                 55.75 
                 −133.19 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −3.9206 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.3689 
                 0.6012 
                 Plastic 
                 1.54 
                 55.75 
                 7.58 
               
               
                 4 
                 Lens 
                 Aspherical 
                 5.1940 
                 0.1610 
               
               
                   
                 Stop 
                 Spherical 
                 1.00E+18 
                 0.3758 
               
               
                 5 
                 Third 
                 Aspherical 
                 61.8096 
                 0.6600 
                 Plastic 
                 1.54 
                 56.11 
                 6.93 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.9979 
                 0.1775 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −3.7517 
                 0.2558 
                 Plastic 
                 1.66 
                 20.38 
                 −9.14 
               
               
                 8 
                 Lens 
                 Aspherical 
                 −10.1765 
                 0.0300 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 −12.1314 
                 0.2500 
                 Plastic 
                 1.54 
                 56.11 
                 703.85 
               
               
                 10 
                 Lens 
                 Aspherical 
                 −11.8443 
                 0.4426 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −3.5108 
                 0.5000 
                 Plastic 
                 1.57 
                 37.40 
                 −7.89 
               
               
                 12 
                 Lens 
                 Aspherical 
                 −17.1340 
                 0.0300 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 2.0970 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.47 
               
               
                 14 
                 Lens 
                 Aspherical 
                 −14.5673 
                 0.5685 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.1085 
                 0.5020 
                 Plastic 
                 1.54 
                 55.75 
                 −5.48 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1249 
                 0.7050 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.0000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.5111 
                 −6.1427 
                 −13.8745 
                 −7.6187 
                 3.3628 
                 −1.8636 
                 −0.3653 
                 −8.2092 
               
               
                 A4 
                 0.0363 
                 0.0365 
                 0.1187 
                 −0.0257 
                 −0.0172 
                 −0.0482 
                 −0.0598 
                 −0.0214 
               
               
                 A6 
                 −0.0099 
                 −0.0132 
                 −0.1125 
                 0.0157 
                 −0.0079 
                 −0.0336 
                 −0.0601 
                 0.0073 
               
               
                 A8 
                 0.0039 
                 0.0088 
                 0.1082 
                 −0.0118 
                 0.0045 
                 0.0588 
                 0.0870 
                 −0.0391 
               
               
                 A10 
                 −0.0010 
                 −0.0035 
                 −0.0772 
                 0.0037 
                 −0.0134 
                 −0.0603 
                 −0.0762 
                 0.0304 
               
               
                 A12 
                 0.0002 
                 0.0009 
                 0.0365 
                 0.0003 
                 0.0122 
                 0.0330 
                 0.0405 
                 −0.0091 
               
               
                 A14 
                 0.0000 
                 −0.0001 
                 −0.0100 
                 −0.0011 
                 −0.0067 
                 −0.0097 
                 −0.0110 
                 0.0010 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0011 
                 0.0003 
                 0.0011 
                 0.0011 
                 0.0012 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 2.5029 
                 −9.5128 
                 −22.7856 
                 −27.6029 
                 −6.9216 
                 −23.6470 
                 −3.8168 
                 −3.0788 
               
               
                 A4 
                 −0.0431 
                 −0.0223 
                 −0.0077 
                 −0.1574 
                 0.0305 
                 0.1982 
                 −0.1119 
                 −0.0733 
               
               
                 A6 
                 0.0754 
                 0.0216 
                 0.0475 
                 0.1096 
                 −0.0041 
                 −0.1121 
                 0.0258 
                 0.0226 
               
               
                 A8 
                 −0.1436 
                 −0.0467 
                 −0.0498 
                 −0.0496 
                 −0.0100 
                 0.0346 
                 −0.0040 
                 −0.0052 
               
               
                 A10 
                 0.1203 
                 0.0395 
                 0.0266 
                 0.0152 
                 0.0049 
                 −0.0071 
                 0.0006 
                 0.0008 
               
               
                 A12 
                 −0.0517 
                 −0.0167 
                 −0.0084 
                 −0.0029 
                 −0.0011 
                 0.0010 
                 −0.0001 
                 −0.0001 
               
               
                 A14 
                 0.0113 
                 0.0034 
                 0.0016 
                 0.0003 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 −0.0010 
                 −0.0003 
                 −0.0002 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     Second Embodiment 
     Referring to  FIGS. 3 and 4 , in the second embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a positive refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a negative refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the second embodiment is included in  FIG. 4 . The astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is concave at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is convex at the paraxial area thereof. The object side surface S 7  is convex at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is concave at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is convex at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is concave at a circumference thereof, and the image side surface S 12  is convex at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is convex at the paraxial area thereof. The object side surface S 13  is convex at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is concave at a circumference thereof, and the image side surface S 16  is convex at the circumference thereof. 
     In addition, various parameters of the lenses of the optical system  10  in the second embodiment are shown in Table 3 and Table 4. Definitions of the various structures and parameters can be obtained from the first embodiment, and which will not be repeated herein. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Second Embodiment 
               
               
                 f = 4.38 mm, FNO = 1.85, FOV = 102.3°, TTL = 7 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −3.8084 
                 0.4505 
                 Plastic 
                 1.54 
                 55.75 
                 256.67 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −3.8584 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.4191 
                 0.5980 
                 Plastic 
                 1.54 
                 55.75 
                 8.09 
               
               
                 4 
                 Lens 
                 Aspherical 
                 5.0111 
                 0.1616 
               
               
                   
                 Stop 
                 Spherical 
                 1.00E+18 
                 0.3671 
               
               
                 5 
                 Third 
                 Aspherical 
                 −998.00 
                 0.6600 
                 Plastic 
                 1.54 
                 56.11 
                 6.55 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.5519 
                 0.1605 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −3.6541 
                 0.2674 
                 Plastic 
                 1.66 
                 20.38 
                 −8.00 
               
               
                 8 
                 Lens 
                 Aspherical 
                 −12.1772 
                 0.0310 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 −12.7644 
                 0.2500 
                 Plastic 
                 1.54 
                 56.11 
                 −2067.26 
               
               
                 10 
                 Lens 
                 Aspherical 
                 −13.0000 
                 0.4403 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −3.4759 
                 0.5401 
                 Plastic 
                 1.57 
                 37.40 
                 −7.59 
               
               
                 12 
                 Lens 
                 Aspherical 
                 −19.0955 
                 0.0410 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 2.0054 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.21 
               
               
                 14 
                 Lens 
                 Aspherical 
                 −10.5888 
                 0.5664 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.3829 
                 0.5020 
                 Plastic 
                 1.54 
                 55.75 
                 −4.99 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1661 
                 0.7068 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.1501 
                 −5.1201 
                 −13.5050 
                 −8.2433 
                 10.0000 
                 −2.1535 
                 −0.2855 
                 7.0696 
               
               
                 A4 
                 0.0291 
                 0.0345 
                 0.1131 
                 −0.0254 
                 −0.0191 
                 −0.0469 
                 −0.0623 
                 −0.0077 
               
               
                 A6 
                 −0.0061 
                 −0.0135 
                 −0.1010 
                 0.0145 
                 −0.0061 
                 −0.0223 
                 −0.0200 
                 −0.0487 
               
               
                 A8 
                 0.0022 
                 0.0094 
                 0.0951 
                 −0.0113 
                 0.0003 
                 0.0351 
                 0.0087 
                 0.0374 
               
               
                 A10 
                 −0.0005 
                 −0.0041 
                 −0.0682 
                 0.0051 
                 −0.0095 
                 −0.0399 
                 −0.0156 
                 −0.0237 
               
               
                 A12 
                 0.0001 
                 0.0012 
                 0.0332 
                 −0.0020 
                 0.0103 
                 0.0235 
                 0.0175 
                 0.0119 
               
               
                 A14 
                 0.0000 
                 −0.0002 
                 −0.0095 
                 0.0001 
                 −0.0067 
                 −0.0076 
                 −0.0066 
                 −0.0032 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0011 
                 0.0001 
                 0.0013 
                 0.0010 
                 0.0008 
                 0.0004 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 5.8084 
                 −6.8313 
                 −25.6596 
                 −22.7983 
                 −8.2157 
                 −23.6470 
                 −3.7493 
                 −3.2138 
               
               
                 A4 
                 −0.0005 
                 0.0128 
                 0.0101 
                 −0.1639 
                 0.0354 
                 0.1989 
                 −0.1039 
                 −0.0652 
               
               
                 A6 
                 −0.1006 
                 −0.0674 
                 0.0217 
                 0.1143 
                 −0.0057 
                 −0.1095 
                 0.0225 
                 0.0187 
               
               
                 A8 
                 0.0964 
                 0.0456 
                 −0.0307 
                 −0.0512 
                 −0.0088 
                 0.0329 
                 −0.0033 
                 −0.0041 
               
               
                 A10 
                 −0.0400 
                 −0.0095 
                 0.0182 
                 0.0154 
                 0.0043 
                 −0.0066 
                 0.0005 
                 0.0006 
               
               
                 A12 
                 0.0057 
                 −0.0026 
                 −0.0061 
                 −0.0028 
                 −0.0010 
                 0.0009 
                 −0.0001 
                 −0.0001 
               
               
                 A14 
                 0.0006 
                 0.0014 
                 0.0012 
                 0.0003 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 −0.0002 
                 −0.0002 
                 −0.0001 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     In this embodiment, the optical system  10  satisfies the following conditions. 
     
       
         
           
               
             
               
                   
               
               
                 Second Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TTL/Imgh 
                 1.30 
                 TTL/f 
                 1.60 
               
               
                   
                 f/R16 
                 3.76 
                 tan(HFOV) 
                 1.24 
               
               
                   
                 SD12/SD21 
                 1.308  
                 T23/CT3 
                 0.80 
               
               
                   
               
            
           
         
       
     
     Third Embodiment 
     Referring to  FIGS. 5 and 6 , in the third embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a negative refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the third embodiment is included in  FIG. 6 . The astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is convex at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is convex at the paraxial area thereof. The object side surface S 7  is convex at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is concave at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is convex at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is concave at a circumference thereof, and the image side surface S 12  is convex at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is convex at the paraxial area thereof. The object side surface S 13  is convex at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is concave at a circumference thereof, and the image side surface S 16  is concave at the circumference thereof. 
     In addition, various parameters of the lenses of the optical system  10  in the third embodiment are shown in Table 5 and Table 6. Definitions of the various structures and parameters can be obtained from the first embodiment, and which will not be repeated herein. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Third Embodiment 
               
               
                 f = 4.36 mm, FNO = 1.78, FOV = 102.4°, TTL = 7 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −3.8389 
                 0.4479 
                 Plastic 
                 1.54 
                 55.75 
                 −131.79 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −4.2251 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.3789 
                 0.6046 
                 Plastic 
                 1.54 
                 55.75 
                 7.73 
               
               
                 4 
                 Lens 
                 Aspherical 
                 5.1029 
                 0.1607 
               
               
                   
                 Stop 
                 Spherical 
                 1.00E+18 
                 0.3744 
               
               
                 5 
                 Third 
                 Aspherical 
                 95.3192 
                 0.6600 
                 Plastic 
                 1.54 
                 56.11 
                 6.79 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.8311 
                 0.1595 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −3.8152 
                 0.2506 
                 Plastic 
                 1.66 
                 20.38 
                 −8.07 
               
               
                 8 
                 Lens 
                 Aspherical 
                 −13.7557 
                 0.0496 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 −13.9199 
                 0.2512 
                 Plastic 
                 1.54 
                 56.11 
                 75.57 
               
               
                 10 
                 Lens 
                 Aspherical 
                 −10.4655 
                 0.3910 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −4.0690 
                 0.5357 
                 Plastic 
                 1.57 
                 37.40 
                 −7.14 
               
               
                 12 
                 Lens 
                 Aspherical 
                 995.0000 
                 0.0502 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 1.9916 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.28 
               
               
                 14 
                 Lens 
                 Aspherical 
                 −13.2994 
                 0.5801 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.1273 
                 0.5032 
                 Plastic 
                 1.54 
                 55.75 
                 −5.56 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1382 
                 0.7240 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.0000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 6 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.4003 
                 −6.3932 
                 −13.6476 
                 −7.8716 
                 10.0000 
                 −3.2982 
                 −0.9043 
                 −3.2739 
               
               
                 A4 
                 0.0359 
                 0.0359 
                 0.1139 
                 −0.0260 
                 −0.0186 
                 −0.0437 
                 −0.0534 
                 −0.0285 
               
               
                 A6 
                 −0.0098 
                 −0.0115 
                 −0.1081 
                 0.0183 
                 −0.0021 
                 −0.0269 
                 −0.0211 
                 0.0027 
               
               
                 A8 
                 0.0037 
                 0.0069 
                 0.1060 
                 −0.0190 
                 −0.0071 
                 0.0405 
                 0.0216 
                 −0.0089 
               
               
                 A10 
                 −0.0010 
                 −0.0024 
                 −0.0776 
                 0.0136 
                 0.0028 
                 −0.0413 
                 −0.0393 
                 −0.0012 
               
               
                 A12 
                 0.0002 
                 0.0005 
                 0.0373 
                 −0.0071 
                 −0.0002 
                 0.0226 
                 0.0356 
                 0.0056 
               
               
                 A14 
                 0.0000 
                 −0.0001 
                 −0.0102 
                 0.0018 
                 −0.0016 
                 −0.0066 
                 −0.0133 
                 −0.0023 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0011 
                 −0.0002 
                 0.0004 
                 0.0007 
                 0.0018 
                 0.0003 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 6.6844 
                 −12.4040 
                 −27.6114 
                 −27.8830 
                 −6.8018 
                 −23.6470 
                 −3.9038 
                 −3.0265 
               
               
                 A4 
                 −0.0230 
                 0.0195 
                 0.0142 
                 −0.1737 
                 0.0271 
                 0.1997 
                 −0.0980 
                 −0.0673 
               
               
                 A6 
                 −0.0434 
                 −0.0538 
                 0.0303 
                 0.1229 
                 0.0022 
                 −0.1084 
                 0.0194 
                 0.0191 
               
               
                 A8 
                 0.0284 
                 0.0115 
                 −0.0417 
                 −0.0541 
                 −0.0128 
                 0.0319 
                 −0.0025 
                 −0.0041 
               
               
                 A10 
                 0.0049 
                 0.0173 
                 0.0237 
                 0.0152 
                 0.0055 
                 −0.0062 
                 0.0004 
                 0.0006 
               
               
                 A12 
                 −0.0105 
                 −0.0125 
                 −0.0075 
                 −0.0025 
                 −0.0012 
                 0.0008 
                 0.0000 
                 −0.0001 
               
               
                 A14 
                 0.0036 
                 0.0031 
                 0.0014 
                 0.0002 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 −0.0004 
                 −0.0003 
                 −0.0001 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     In this embodiment, the optical system  10  satisfies the following conditions. 
     
       
         
           
               
             
               
                   
               
               
                 Third Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TTL/Imgh 
                 1.30 
                 TTL/f 
                 1.61 
               
               
                   
                 f/R16 
                 3.83 
                 tan(HFOV) 
                 1.24 
               
               
                   
                 SD12/SD21 
                 1.276 
                 T23/CT3 
                 0.81 
               
               
                   
               
            
           
         
       
     
     Fourth Embodiment 
     Referring to  FIGS. 7 and 8 , in the fourth embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a negative refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the fourth embodiment is included in  FIG. 8 . The astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is convex at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is convex at the paraxial area thereof. The object side surface S 7  is convex at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is convex at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is convex at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is concave at a circumference thereof, and the image side surface S 12  is convex at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is concave at the paraxial area thereof. The object side surface S 13  is convex at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is convex at a circumference thereof, and the image side surface S 16  is concave at the circumference thereof. 
     In addition, various parameters of the lenses of the optical system  10  in the fourth embodiment are shown in Table 7 and Table 8. Definitions of the various structures and parameters can be obtained from the first embodiment, and which will not be repeated herein. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Fourth Embodiment 
               
               
                 f = 4.41 mm, FNO = 1.85, FOV = 102.6°, TTL = 7 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −3.9715 
                 0.4500 
                 Plastic 
                 1.54 
                 55.75 
                 −166.72 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −4.3207 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.3649 
                 0.5980 
                 Plastic 
                 1.54 
                 55.75 
                 7.84 
               
               
                 4 
                 Lens 
                 Aspherical 
                 4.9463 
                 0.1724 
               
               
                   
                 Stop 
                 Spherical 
                 1.00E+18 
                 0.3714 
               
               
                 5 
                 Third 
                 Aspherical 
                 74.8712 
                 0.6600 
                 Plastic 
                 1.54 
                 56.11 
                 6.91 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.9439 
                 0.1567 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −3.8058 
                 0.2793 
                 Plastic 
                 1.66 
                 20.38 
                 −7.60 
               
               
                 8 
                 Lens 
                 Aspherical 
                 −16.1443 
                 0.0340 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 998.0000 
                 0.2500 
                 Plastic 
                 1.54 
                 56.11 
                 35.51 
               
               
                 10 
                 Lens 
                 Aspherical 
                 −19.6985 
                 0.4376 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −3.3201 
                 0.5064 
                 Plastic 
                 1.57 
                 37.40 
                 −8.17 
               
               
                 12 
                 Lens 
                 Aspherical 
                 −12.3666 
                 0.0300 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 1.9697 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.69 
               
               
                 14 
                 Lens 
                 Aspherical 
                 995.0000 
                 0.5982 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.0415 
                 0.5020 
                 Plastic 
                 1.54 
                 55.75 
                 −5.91 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1344 
                 0.6967 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.0000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 8 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.1630 
                 −5.5948 
                 −12.1402 
                 −6.8019 
                 10.0000 
                 −1.7205 
                 −0.9802 
                 7.5960 
               
               
                 A4 
                 0.0336 
                 0.0355 
                 0.1040 
                 −0.0235 
                 −0.0201 
                 −0.0533 
                 −0.0689 
                 −0.0368 
               
               
                 A6 
                 −0.0088 
                 −0.0126 
                 −0.0878 
                 0.0137 
                 −0.0045 
                 −0.0159 
                 0.0076 
                 0.0123 
               
               
                 A8 
                 0.0033 
                 0.0078 
                 0.0791 
                 −0.0111 
                 −0.0042 
                 0.0286 
                 −0.0131 
                 −0.0169 
               
               
                 A10 
                 −0.0008 
                 −0.0031 
                 −0.0548 
                 0.0050 
                 −0.0019 
                 −0.0330 
                 −0.0004 
                 0.0055 
               
               
                 A12 
                 0.0001 
                 0.0008 
                 0.0259 
                 −0.0017 
                 0.0033 
                 0.0191 
                 0.0077 
                 0.0016 
               
               
                 A14 
                 0.0000 
                 −0.0001 
                 −0.0073 
                 0.0000 
                 −0.0027 
                 −0.0057 
                 −0.0034 
                 −0.0011 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0009 
                 0.0001 
                 0.0004 
                 0.0006 
                 0.0005 
                 0.0002 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 −12.4040 
                 5.6791 
                 −27.7800 
                 −27.8830 
                 −8.1068 
                 −23.6470 
                 −4.3607 
                 −3.1332 
               
               
                 A4 
                 −0.0244 
                 0.0167 
                 −0.0207 
                 −0.1669 
                 0.0391 
                 0.1808 
                 −0.1119 
                 −0.0735 
               
               
                 A6 
                 −0.0379 
                 −0.0443 
                 0.0623 
                 0.1239 
                 −0.0113 
                 −0.1074 
                 0.0291 
                 0.0232 
               
               
                 A8 
                 0.0162 
                 0.0089 
                 −0.0618 
                 −0.0612 
                 −0.0077 
                 0.0338 
                 −0.0057 
                 −0.0055 
               
               
                 A10 
                 0.0066 
                 0.0113 
                 0.0331 
                 0.0205 
                 0.0045 
                 −0.0070 
                 0.0009 
                 0.0009 
               
               
                 A12 
                 −0.0071 
                 −0.0080 
                 −0.0106 
                 −0.0042 
                 −0.0011 
                 0.0010 
                 −0.0001 
                 −0.0001 
               
               
                 A14 
                 0.0021 
                 0.0019 
                 0.0020 
                 0.0005 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 −0.0002 
                 −0.0002 
                 −0.0002 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     In this embodiment, the optical system  10  satisfies the following conditions. 
     
       
         
           
               
             
               
                   
               
               
                 Fourth Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TTL/Imgh 
                 1.30 
                 TTL/f 
                 1.59 
               
               
                   
                 f/R16 
                 3.89 
                 tan(HFOV) 
                 1.25 
               
               
                   
                 SD12/SD21 
                 1.300 
                 T23/CT3 
                 0.82 
               
               
                   
               
            
           
         
       
     
     Fifth Embodiment 
     Referring to  FIGS. 9 and 10 , in the fifth embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a negative refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a negative refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the fifth embodiment is included in  FIG. 10 . The astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is convex at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is convex at the paraxial area thereof. The object side surface S 7  is concave at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is concave at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is concave at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is concave at a circumference thereof, and the image side surface S 12  is convex at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is convex at the paraxial area thereof. The object side surface S 13  is concave at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is convex at a circumference thereof, and the image side surface S 16  is concave at the circumference thereof. 
     In addition, various parameters of the lenses of the optical system  10  in the fifth embodiment are shown in Table 9 and Table 10. Definitions of the various structures and parameters can be obtained from the first embodiment, and which will not be repeated herein. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Fifth Embodiment 
               
               
                 f = 4.42 mm, FNO = 1.85, FOV = 102.4°, TTL = 7 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −3.8452 
                 0.4454 
                 Plastic 
                 1.54 
                 55.75 
                 −122.06 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −4.2507 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.3456 
                 0.6037 
                 Plastic 
                 1.54 
                 55.75 
                 7.57 
               
               
                 4 
                 Lens 
                 Aspherical 
                 5.0748 
                 0.1647 
               
               
                   
                 Stop 
                 Aspherical 
                 1.00E+18 
                 0.3759 
               
               
                 5 
                 Third 
                 Aspherical 
                 73.1048 
                 0.6660 
                 Plastic 
                 1.54 
                 56.11 
                 6.38 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.6298 
                 0.1220 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −3.7813 
                 0.2801 
                 Plastic 
                 1.66 
                 20.38 
                 −8.47 
               
               
                 8 
                 Lens 
                 Aspherical 
                 −12.0000 
                 0.0300 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 −74.4954 
                 0.2500 
                 Plastic 
                 1.54 
                 56.11 
                 −127.39 
               
               
                 10 
                 Lens 
                 Aspherical 
                 998.0000 
                 0.4271 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −3.6789 
                 0.5193 
                 Plastic 
                 1.57 
                 37.40 
                 −7.55 
               
               
                 12 
                 Lens 
                 Aspherical 
                 −27.4593 
                 0.0503 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 2.0014 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.27 
               
               
                 14 
                 Lens 
                 Aspherical 
                 −12.4113 
                 0.6059 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.4239 
                 0.5020 
                 Plastic 
                 1.54 
                 55.75 
                 −5.07 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1872 
                 0.7003 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.0000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 10 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.2817 
                 −5.7810 
                 −11.6878 
                 −7.2294 
                 3.3331 
                 −1.9182 
                 −1.6194 
                 −7.5380 
               
               
                 A4 
                 0.0345 
                 0.0353 
                 0.1030 
                 −0.0232 
                 −0.0190 
                 −0.0489 
                 −0.0354 
                 0.0163 
               
               
                 A6 
                 −0.0092 
                 −0.0121 
                 −0.0864 
                 0.0143 
                 −0.0056 
                 −0.0262 
                 −0.0416 
                 −0.0782 
               
               
                 A8 
                 0.0034 
                 0.0075 
                 0.0808 
                 −0.0138 
                 0.0010 
                 0.0383 
                 0.0150 
                 0.0752 
               
               
                 A10 
                 −0.0009 
                 −0.0029 
                 −0.0593 
                 0.0088 
                 −0.0120 
                 −0.0341 
                 −0.0015 
                 −0.0529 
               
               
                 A12 
                 0.0001 
                 0.0008 
                 0.0297 
                 −0.0046 
                 0.0127 
                 0.0161 
                 0.0004 
                 0.0238 
               
               
                 A14 
                 0.0000 
                 −0.0001 
                 −0.0087 
                 0.0010 
                 −0.0076 
                 −0.0042 
                 0.0004 
                 −0.0057 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0010 
                 0.0000 
                 0.0015 
                 0.0004 
                 −0.0002 
                 0.0006 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 −5.1641 
                 −12.4040 
                 −27.7800 
                 −7.8830 
                 −8.6649 
                 −16.9991 
                 −4.0007 
                 −3.2604 
               
               
                 A4 
                 −0.0212 
                 −0.0025 
                 0.0071 
                 −0.1753 
                 0.0318 
                 0.1881 
                 −0.1057 
                 −0.0647 
               
               
                 A6 
                 −0.1270 
                 −0.0735 
                 0.0280 
                 0.1295 
                 −0.0033 
                 −0.1010 
                 0.0246 
                 0.0187 
               
               
                 A8 
                 0.1592 
                 0.0591 
                 −0.0389 
                 −0.0639 
                 −0.0101 
                 0.0293 
                 −0.0039 
                 −0.0040 
               
               
                 A10 
                 −0.0961 
                 −0.0194 
                 0.0237 
                 0.0214 
                 0.0047 
                 −0.0056 
                 0.0006 
                 0.0006 
               
               
                 A12 
                 0.0320 
                 0.0016 
                 −0.0082 
                 −0.0044 
                 −0.0010 
                 0.0007 
                 −0.0001 
                 −0.0001 
               
               
                 A14 
                 −0.0056 
                 0.0004 
                 0.0016 
                 0.0005 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 0.0004 
                 −0.0001 
                 −0.0002 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     In this embodiment, the optical system  10  satisfies the following conditions. 
     
       
         
           
               
             
               
                   
               
               
                 Fifth Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TTL/Imgh 
                 1.30 
                 TTL/f 
                 1.58 
               
               
                   
                 f/R16 
                 3.72 
                 tan(HFOV) 
                 1.24 
               
               
                   
                 SD12/SD21 
                 1.296 
                 T23/CT3 
                 0.81 
               
               
                   
               
            
           
         
       
     
     Sixth Embodiment 
     Referring to  FIGS. 11 and 12 , in the sixth embodiment, the optical system  10  includes, successively in order from an object side to an image side, a first lens L 1  having a negative refractive power, a second lens L 2  having a positive refractive power, a stop STO, a third lens L 3  having a positive refractive power, a fourth lens L 4  having a negative refractive power, a fifth lens L 5  having a positive refractive power, a sixth lens L 6  having a negative refractive power, a seventh lens L 7  having a positive refractive power, and an eighth lens L 8  having a negative refractive power. A longitudinal spherical aberration diagram (mm), an astigmatism diagram (mm), and a distortion diagram (%) of the optical system  10  in the sixth embodiment is included in  FIG. 12 . The astigmatism diagram and the distortion diagram are graphs at a wavelength of 555 nm. 
     An object side surface S 1  of the first lens L 1  is concave at a paraxial area thereof, and an image side surface S 2  of the first lens L 1  is convex at the paraxial area thereof. the object side surface S 1  is convex at a circumference thereof, and the image side surface S 2  is concave at the circumference thereof. 
     An object side surface S 3  of the second lens L 2  is convex at a paraxial area thereof, and an image side surface S 4  of the second lens L 2  is concave at the paraxial area thereof. The object side surface S 3  is concave at a circumference thereof, and the image side surface S 4  is convex at the circumference thereof. 
     An object side surface S 5  of the third lens L 3  is convex at a paraxial area thereof, and an image side surface S 6  of the third lens L 3  is convex at the paraxial area thereof. the object side surface S 5  is concave at a circumference thereof, and the image side surface S 6  is convex at the circumference thereof. 
     An object side surface S 7  of the fourth lens L 4  is concave at a paraxial area thereof, and an image side surface S 8  of the fourth lens L 4  is concave at the paraxial area thereof. The object side surface S 7  is concave at a circumference thereof, and the image side surface S 8  is concave at the circumference thereof. 
     An object side surface S 9  of the fifth lens L 5  is concave at a paraxial area thereof, and an image side surface S 10  of the fifth lens L 5  is convex at the paraxial area thereof. The object side surface S 9  is convex at a circumference thereof, and the image side surface S 10  is concave at the circumference thereof. 
     An object side surface S 11  of the sixth lens L 6  is concave at a paraxial area thereof, and an image side surface S 12  of the sixth lens L 6  is convex at the paraxial area thereof. The object side surface S 11  is concave at a circumference thereof, and the image side surface S 12  is convex at the circumference thereof. 
     An object side surface S 13  of the seventh lens L 7  is convex at a paraxial area thereof, and an image side surface S 14  of the seventh lens L 7  is convex at the paraxial area thereof. The object side surface S 13  is concave at a circumference thereof, and the image side surface S 14  is convex at the circumference thereof. 
     An object side surface S 15  of the eighth lens L 8  is convex at a paraxial area thereof, and an image side surface S 16  of the eighth lens L 8  is concave at the paraxial area thereof. The object side surface S 15  is convex at a circumference thereof, and the image side surface S 16  is concave at the circumference thereof. 
     In addition, various parameters of the lenses of the optical system  10  in the sixth embodiment are shown in Table 11 and Table 12. Definitions of the various structures and parameters can be obtained from the first embodiment, and which will not be repeated herein. 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Sixth Embodiment 
               
               
                 f = 4.44 mm, FNO = 1.88, FOV = 102.3°, TTL = 7.02 mm 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Surface 
                 Surface 
                 Surface 
                 Y radius 
                 Thickness 
                   
                 Refractive 
                 Abbe 
                 Focal Length 
               
               
                 Number 
                 Name 
                 Shape 
                 (mm) 
                 (mm) 
                 Material 
                 index 
                 number 
                 (mm) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Object 
                 Spherical 
                 Infinite 
                 Infinite 
                   
                   
                   
                   
               
               
                   
                 Surface 
               
               
                 1 
                 First 
                 Aspherical 
                 −4.0777 
                 0.4538 
                 Plastic 
                 1.54 
                 55.75 
                 105.34 
               
               
                 2 
                 Lens 
                 Aspherical 
                 −4.5662 
                 0.0300 
               
               
                 3 
                 Second 
                 Aspherical 
                 2.3387 
                 0.5980 
                 Plastic 
                 1.54 
                 55.75 
                 7.68 
               
               
                 4 
                 Lens 
                 Aspherical 
                 4.9486 
                 0.1726 
               
               
                   
                 Stop 
                 Spherical 
                 1.00E+18 
                 0.3697 
                 Plastic 
               
               
                 5 
                 Third 
                 Aspherical 
                 64.3505 
                 0.6613 
                 Plastic 
                 1.54 
                 56.11 
                 6.63 
               
               
                 6 
                 Lens 
                 Aspherical 
                 −3.8097 
                 0.1227 
               
               
                 7 
                 Fourth 
                 Aspherical 
                 −5.1395 
                 0.2868 
                 Plastic 
                 1.66 
                 20.38 
                 −7.61 
               
               
                 8 
                 Lens 
                 Aspherical 
                 234.0657 
                 0.1028 
               
               
                 9 
                 Fifth 
                 Aspherical 
                 −24.0206 
                 0.2500 
                 Plastic 
                 1.54 
                 56.11 
                 26.50 
               
               
                 10 
                 Lens 
                 Aspherical 
                 −9.0426 
                 0.3785 
               
               
                 11 
                 Sixth 
                 Aspherical 
                 −2.9365 
                 0.5278 
                 Plastic 
                 1.57 
                 37.40 
                 −7.06 
               
               
                 12 
                 Lens 
                 Aspherical 
                 −11.7067 
                 0.0308 
               
               
                 13 
                 Seventh 
                 Aspherical 
                 2.1497 
                 0.6060 
                 Plastic 
                 1.54 
                 55.75 
                 3.41 
               
               
                 14 
                 Lens 
                 Aspherical 
                 −10.8384 
                 0.6022 
               
               
                 15 
                 Eighth 
                 Aspherical 
                 2.4286 
                 0.5020 
                 Plastic 
                 1.54 
                 55.75 
                 −4.98 
               
               
                 16 
                 Lens 
                 Aspherical 
                 1.1792 
                 0.7038 
               
               
                 17 
                 Infrared 
                 Spherical 
                 Infinite 
                 0.2100 
                 Glass 
               
               
                 18 
                 Cut-off 
                 Spherical 
                 Infinite 
                 0.4113 
               
               
                   
                 Filter 
               
               
                   
                 Imaging 
                 Spherical 
                 Infinite 
                 0.0000 
               
               
                   
                 Surface 
               
               
                   
               
               
                 Note: 
               
               
                 the reference wavelength is 555 nm 
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
               
               
               
             
               
                 TABLE 12 
               
               
                   
               
             
            
               
                 Surface Number 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
               
               
                 K 
                 −1.3217 
                 −6.6965 
                 −12.5288 
                 −6.6809 
                 −10.0000 
                 −1.9732 
                 0.9859 
                 −12.4040 
               
               
                 A4 
                 0.0353 
                 0.0369 
                 0.1104 
                 −0.0234 
                 −0.0174 
                 −0.0510 
                 −0.0786 
                 −0.0545 
               
               
                 A6 
                 −0.0094 
                 −0.0123 
                 −0.0971 
                 0.0130 
                 −0.0079 
                 −0.0287 
                 −0.0108 
                 0.0116 
               
               
                 A8 
                 0.0035 
                 0.0075 
                 0.0896 
                 −0.0081 
                 0.0052 
                 0.0621 
                 0.0442 
                 0.0042 
               
               
                 A10 
                 −0.0009 
                 −0.0028 
                 −0.0632 
                 0.0004 
                 −0.0173 
                 −0.0758 
                 −0.0686 
                 −0.0167 
               
               
                 A12 
                 0.0002 
                 0.0007 
                 0.0301 
                 0.0017 
                 0.0179 
                 0.0480 
                 0.0487 
                 0.0121 
               
               
                 A14 
                 0.0000 
                 −0.0001 
                 −0.0085 
                 −0.0013 
                 −0.0102 
                 −0.0157 
                 −0.0155 
                 −0.0035 
               
               
                 A16 
                 0.0000 
                 0.0000 
                 0.0010 
                 0.0003 
                 0.0020 
                 0.0020 
                 0.0018 
                 0.0004 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
               
                 Surface Number 
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
                 15 
                 16 
               
               
                   
               
               
                 K 
                 7.5960 
                 −12.4040 
                 −19.8565 
                 −27.8750 
                 −8.8148 
                 −23.6470 
                 −3.6255 
                 −3.2624 
               
               
                 A4 
                 −0.0406 
                 0.0040 
                 −0.0270 
                 −0.1658 
                 0.0368 
                 0.2004 
                 −0.1085 
                 −0.0645 
               
               
                 A6 
                 −0.0061 
                 −0.0046 
                 0.0770 
                 0.1173 
                 −0.0062 
                 −0.1105 
                 0.0260 
                 0.0187 
               
               
                 A8 
                 −0.0099 
                 −0.0320 
                 −0.0744 
                 −0.0545 
                 −0.0096 
                 0.0331 
                 −0.0045 
                 −0.0040 
               
               
                 A10 
                 0.0214 
                 0.0357 
                 0.0396 
                 0.0169 
                 0.0048 
                 −0.0065 
                 0.0007 
                 0.0006 
               
               
                 A12 
                 −0.0127 
                 −0.0162 
                 −0.0127 
                 −0.0032 
                 −0.0011 
                 0.0009 
                 −0.0001 
                 −0.0001 
               
               
                 A14 
                 0.0033 
                 0.0034 
                 0.0024 
                 0.0003 
                 0.0001 
                 −0.0001 
                 0.0000 
                 0.0000 
               
               
                 A16 
                 −0.0003 
                 −0.0003 
                 −0.0003 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A18 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                 A20 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
                 0.0000 
               
               
                   
               
            
           
         
       
     
     In this embodiment, the optical system  10  satisfies the following conditions. 
     
       
         
           
               
             
               
                   
               
               
                 Sixth Embodiment 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TTL/Imgh 
                 1.30 
                 TTL/f 
                 1.58 
               
               
                   
                 f/R16 
                 3.77 
                 tan(HFOV) 
                 1.24 
               
               
                   
                 SD12/SD21 
                 1.285 
                 T23/CT3 
                 0.82 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 13 , in an embodiment of the present disclosure, the optical system  10  and a photosensitive element  210  are assembled to form a camera module  20 . The photosensitive element  210  is arranged on the image side of the eighth lens L 8 , that is, on the image side of the optical system  10 . Generally, a photosensitive surface of the photosensitive element  210  overlaps the imaging surface S 19  of the optical system  10 . In this embodiment, an infrared cut-off filter L 9  is further arranged between the eighth lens L 8  and the photosensitive element  210 . The photosensitive element  210  may be a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS). By adopting the above optical system  10 , the camera module  20  can have excellent capturing quality. 
     In some embodiments, a distance between the photosensitive element  210  and each of the lenses in the optical system  10  is relatively fixed. As such, the camera module  20  is a fixed focus module. In other embodiments, a driving mechanism such as a voice coil motor may be provided to enable the photosensitive element  210  to move relative to each of the lenses in the optical system  10 , thereby achieving a focusing effect. Specifically, a coil electrically connected to a driving chip is provided on a lens barrel equipped with the above lenses, and the camera module  20  is further provided with a magnet. The magnetic force between the energized coil and the magnet is used to drive the lens barrel to move relative to the photosensitive element  210 , thereby achieving a focusing effect. In other embodiments, a similar driving mechanism can also be provided to drive part of the lenses in the optical system  10  to move, so as to achieve an optical zooming effect. 
     Referring to  FIG. 14 , some embodiments of the present disclosure further provide an electronic device  30 . The camera module  20  is applied to the electronic device  30  such that the electronic device  30  has a capturing function. Specifically, the electronic device  30  includes a fixing member  310 . The camera module  20  is mounted on the fixing member  310 . The fixing member  310  may be a circuit board, a middle frame, and the like. The electronic device  30  includes, but is not limited to, smart phones, smart watches, e-book readers, in-vehicle camera devices, monitoring devices, medical devices (such as endoscopes), tablet computers, biometric devices (such as fingerprint recognition devices or pupil recognition devices), personal digital assistants (PDAs), unmanned aerial vehicles, etc. Specifically, in some embodiments, the electronic device  30  is a smart phone. The smart phone includes a middle frame and a circuit board provided in the middle frame. The camera module  20  is mounted in the middle frame of the smart phone. The photosensitive element  210  therein is electrically connected to the circuit board. The camera module  20  can be used as a front camera module or a rear camera module of a smart phone. By adopting the above camera module  20  according to the embodiments of the present disclosure, the electronic device  30  can have excellent capturing function. 
     In the description of the present disclosure, it should be understood that orientation or positional conditions indicated by terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential” etc. are based on orientation or positional condition shown in the drawings, which are merely to facilitate the description of the present disclosure and simplify the description, not to indicate or imply that the device or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be construed as a limitation on the present disclosure. 
     In addition, the terms “first” and “second” are used for description only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined with “first” and “second” may include at least one of the features explicitly or implicitly. In the description of the present disclosure, the meaning of “plurality” is at least two, for example, two, three or the like, unless explicitly and specifically defined otherwise. 
     In the present disclosure, unless explicitly specified and defined otherwise, terms “mounting”, “connecting”, “connected”, and “fixing” should be understood in a broad sense. For example, it may be a fixed connection or a detachable connection, or an integration; may be a mechanical connection or electrical connection; may be a direct connection, or may be a connection through an intermediate medium, may be the communication between two elements or the interaction between two elements, unless explicitly defined otherwise. The specific meanings of the above terms in the present disclosure can be understood by one of those ordinary skills in the art according to specific circumstances. 
     In the present disclosure, unless expressly specified and defined otherwise, a first feature being “on” or “below” a second feature may mean that the first feature is in direct contact with the second feature, or may mean that the first feature is in indirect contact with the second feature through an intermediate medium. Moreover, the first feature being “above”, “top” and “upside” on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply mean that the level of the first feature is higher than that of the second feature. The first feature being “below”, “under” and “beneath” the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply mean that the level of the first feature is smaller than that of the second feature. 
     In the description of this specification, descriptions referring to terms “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” and the like mean that specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials, or characteristics can be combined in any one or more embodiments or examples in a suitable manner. In addition, if there is no contradiction, the different embodiments or examples and the features of the different embodiments or examples described in this specification can be combined and incorporated by those skilled in the art. 
     The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to simply the description, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combinations of these technical features, they should be considered to be fallen into the range described in the present specification. 
     Only several embodiments of the present disclosure are illustrated in the above-mentioned embodiments, and the description thereof is relatively specific and detailed, but it should not be understood as a limitation on the scope of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several modifications and improvements can be made, which all fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the appended claims.